Rename PAINT to PALETTE (#4161)

* /paint to /palette

* rename paint to palette

* rename the modules in palette to be pallets

* update Structure.adoc

* bump impl

* fix CI directory

* Update docs/Structure.adoc

Co-Authored-By: Benjamin Kampmann <ben@gnunicorn.org>

substrate/palette/support/src/debug.rs

@@ -0,0 +1,215 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Runtime debugging and logging utilities.
+//!
+//! This module contains macros and functions that will allow
+//! you to print logs out of the runtime code.
+//!
+//! First and foremost be aware that adding regular logging code to
+//! your runtime will have a negative effect on the performance
+//! and size of the blob. Luckily there are some ways to mitigate
+//! this that are described below.
+//!
+//! First component to utilize debug-printing and loggin is actually
+//! located in `primitives` crate: `primitives::RuntimeDebug`.
+//! This custom-derive generates `core::fmt::Debug` implementation,
+//! just like regular `derive(Debug)`, however it does not generate
+//! any code when the code is compiled to WASM. This means that
+//! you can safely sprinkle `RuntimeDebug` in your runtime codebase,
+//! without affecting the size. This also allows you to print/log
+//! both when the code is running natively or in WASM, but note
+//! that WASM debug formatting of structs will be empty.
+//!
+//! ```rust,no_run
+//!	use palette_support::debug;
+//!
+//! #[derive(primitives::RuntimeDebug)]
+//!	struct MyStruct {
+//!   a: u64,
+//!	}
+//!
+//! // First initialize the logger.
+//! //
+//! // This is only required when you want the logs to be printed
+//! // also during non-native run.
+//! // Note that enabling the logger has performance impact on
+//! // WASM runtime execution and should be used sparingly.
+//!	debug::RuntimeLogger::init();
+//!
+//! let x = MyStruct { a: 5 };
+//!	// will log an info line `"My struct: MyStruct{a:5}"` when running
+//!	// natively, but will only print `"My struct: "` when running WASM.
+//!	debug::info!("My struct: {:?}", x);
+//!
+//!	// same output here, although this will print to stdout
+//!	// (and without log format)
+//!	debug::print!("My struct: {:?}", x);
+//! ```
+//!
+//! If you want to avoid extra overhead in WASM, but still be able
+//! to print / log when the code is executed natively you can use
+//! macros coming from `native` sub-module. This module enables
+//! logs conditionally and strips out logs in WASM.
+//!
+//! ```rust,no_run
+//!	use palette_support::debug::native;
+//!
+//! #[derive(primitives::RuntimeDebug)]
+//!	struct MyStruct {
+//!   a: u64,
+//!	}
+//!
+//! // We don't initialize the logger, since
+//! // we are not printing anything out in WASM.
+//!	// debug::RuntimeLogger::init();
+//!
+//! let x = MyStruct { a: 5 };
+//!
+//!	// Displays an info log when running natively, nothing when WASM.
+//!	native::info!("My struct: {:?}", x);
+//!
+//!	// same output to stdout, no overhead on WASM.
+//!	native::print!("My struct: {:?}", x);
+//! ```
+
+use rstd::vec::Vec;
+use rstd::fmt::{self, Debug};
+
+pub use log::{info, debug, error, trace, warn};
+pub use crate::runtime_print as print;
+
+/// Native-only logging.
+///
+/// Using any functions from this module will have any effect
+/// only if the runtime is running natively (i.e. not via WASM)
+#[cfg(feature = "std")]
+pub mod native {
+	pub use super::{info, debug, error, trace, warn, print};
+}
+
+/// Native-only logging.
+///
+/// Using any functions from this module will have any effect
+/// only if the runtime is running natively (i.e. not via WASM)
+#[cfg(not(feature = "std"))]
+pub mod native {
+	#[macro_export]
+	macro_rules! noop {
+		($($arg:tt)+) => {}
+	}
+	pub use noop as info;
+	pub use noop as debug;
+	pub use noop as error;
+	pub use noop as trace;
+	pub use noop as warn;
+	pub use noop as print;
+}
+
+/// Print out a formatted message.
+///
+/// # Example
+///
+/// ```
+/// palette_support::runtime_print!("my value is {}", 3);
+/// ```
+#[macro_export]
+macro_rules! runtime_print {
+	($($arg:tt)+) => {
+		use core::fmt::Write;
+		let mut w = $crate::debug::Writer::default();
+		let _ = core::write!(&mut w, $($arg)+);
+		w.print();
+	}
+}
+
+/// Print out the debuggable type.
+pub fn debug(data: &impl Debug) {
+	runtime_print!("{:?}", data);
+}
+
+/// A target for `core::write!` macro - constructs a string in memory.
+#[derive(Default)]
+pub struct Writer(Vec<u8>);
+
+impl fmt::Write for Writer {
+	fn write_str(&mut self, s: &str) -> fmt::Result {
+		self.0.extend(s.as_bytes());
+		Ok(())
+	}
+}
+
+impl Writer {
+	/// Print the content of this `Writer` out.
+	pub fn print(&self) {
+		runtime_io::misc::print_utf8(&self.0)
+	}
+}
+
+/// Runtime logger implementation - `log` crate backend.
+///
+/// The logger should be initialized if you want to display
+/// logs inside the runtime that is not necessarily running natively.
+///
+/// When runtime is executed natively any log statements are displayed
+/// even if this logger is NOT initialized.
+///
+/// Note that even though the logs are not displayed in WASM, they
+/// may still affect the size and performance of the generated runtime.
+/// To lower the footprint make sure to only use macros from `native`
+/// sub-module.
+pub struct RuntimeLogger;
+
+impl RuntimeLogger {
+	/// Initialize the logger.
+	///
+	/// This is a no-op when running natively (`std`).
+	#[cfg(feature = "std")]
+	pub fn init() {}
+
+	/// Initialize the logger.
+	///
+	/// This is a no-op when running natively (`std`).
+	#[cfg(not(feature = "std"))]
+	pub fn init() {
+		static LOGGER: RuntimeLogger = RuntimeLogger;;
+		let _ = log::set_logger(&LOGGER);
+	}
+}
+
+impl log::Log for RuntimeLogger {
+	fn enabled(&self, _metadata: &log::Metadata) -> bool {
+		// to avoid calling to host twice, we pass everything
+		// and let the host decide what to print.
+		// If someone is initializing the logger they should
+		// know what they are doing.
+		true
+	}
+
+	fn log(&self, record: &log::Record) {
+		use fmt::Write;
+		let mut w = Writer::default();
+		let _ = core::write!(&mut w, "{}", record.args());
+
+		runtime_io::logging::log(
+			record.level().into(),
+			record.target(),
+			&w.0,
+		);
+	}
+
+	fn flush(&self) {}
+}

substrate/palette/support/src/error.rs

@@ -0,0 +1,166 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Macro for declaring a module error.
+
+#[doc(hidden)]
+pub use sr_primitives::traits::LookupError;
+pub use palette_metadata::{ModuleErrorMetadata, ErrorMetadata, DecodeDifferent};
+
+/// Declare an error type for a runtime module.
+///
+/// The generated error type inherently has the variants `Other` and `CannotLookup`. `Other` can
+/// hold any `&'static str` error message and is present for convenience/backward compatibility.
+/// The `CannotLookup` variant indicates that some lookup could not be done. For both variants the
+/// error type implements `From<&'static str>` and `From<LookupError>` to make them usable with the
+/// try operator.
+///
+/// # Usage
+///
+/// ```
+/// # use palette_support::decl_error;
+/// decl_error! {
+///     /// Errors that can occur in my module.
+///     pub enum MyError {
+///         /// Hey this is an error message that indicates bla.
+///         MyCoolErrorMessage,
+///         /// You are just not cool enough for my module!
+///         YouAreNotCoolEnough,
+///     }
+/// }
+/// ```
+///
+/// `decl_error!` supports only variants that do not hold any data.
+#[macro_export]
+macro_rules! decl_error {
+	(
+		$(#[$attr:meta])*
+		pub enum $error:ident {
+			$(
+				$( #[doc = $doc_attr:tt] )*
+				$name:ident
+			),*
+			$(,)?
+		}
+	) => {
+		#[derive(Clone, PartialEq, Eq, $crate::RuntimeDebug)]
+		$(#[$attr])*
+		pub enum $error {
+			Other(&'static str),
+			CannotLookup,
+			$(
+				$( #[doc = $doc_attr] )*
+				$name
+			),*
+		}
+
+		impl $crate::dispatch::ModuleDispatchError for $error {
+			fn as_u8(&self) -> u8 {
+				$crate::decl_error! {
+					@GENERATE_AS_U8
+					self
+					$error
+					{}
+					2,
+					$( $name ),*
+				}
+			}
+
+			fn as_str(&self) -> &'static str {
+				match self {
+					$error::Other(err) => err,
+					$error::CannotLookup => "Can not lookup",
+					$(
+						$error::$name => stringify!($name),
+					)*
+				}
+			}
+		}
+
+		impl From<&'static str> for $error {
+			fn from(val: &'static str) -> $error {
+				$error::Other(val)
+			}
+		}
+
+		impl From<$crate::error::LookupError> for $error {
+			fn from(_: $crate::error::LookupError) -> $error {
+				$error::CannotLookup
+			}
+		}
+
+		impl From<$error> for &'static str {
+			fn from(err: $error) -> &'static str {
+				use $crate::dispatch::ModuleDispatchError;
+				err.as_str()
+			}
+		}
+
+		impl Into<$crate::dispatch::DispatchError> for $error {
+			fn into(self) -> $crate::dispatch::DispatchError {
+				use $crate::dispatch::ModuleDispatchError;
+				$crate::dispatch::DispatchError::new(None, self.as_u8(), Some(self.as_str()))
+			}
+		}
+
+		impl $crate::error::ModuleErrorMetadata for $error {
+			fn metadata() -> &'static [$crate::error::ErrorMetadata] {
+				&[
+					$(
+						$crate::error::ErrorMetadata {
+							name: $crate::error::DecodeDifferent::Encode(stringify!($name)),
+							documentation: $crate::error::DecodeDifferent::Encode(&[
+								$( $doc_attr ),*
+							]),
+						}
+					),*
+				]
+			}
+		}
+	};
+	(@GENERATE_AS_U8
+		$self:ident
+		$error:ident
+		{ $( $generated:tt )* }
+		$index:expr,
+		$name:ident
+		$( , $rest:ident )*
+	) => {
+		$crate::decl_error! {
+			@GENERATE_AS_U8
+			$self
+			$error
+			{
+				$( $generated )*
+				$error::$name => $index,
+			}
+			$index + 1,
+			$( $rest ),*
+		}
+	};
+	(@GENERATE_AS_U8
+		$self:ident
+		$error:ident
+		{ $( $generated:tt )* }
+		$index:expr,
+	) => {
+		match $self {
+			$error::Other(_) => 0,
+			$error::CannotLookup => 1,
+			$( $generated )*
+		}
+	}
+}

substrate/palette/support/src/event.rs

@@ -0,0 +1,819 @@
+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+//! Macros that define an Event types. Events can be used to easily report changes or conditions
+//! in your runtime to external entities like users, chain explorers, or dApps.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+pub use palette_metadata::{EventMetadata, DecodeDifferent, OuterEventMetadata, FnEncode};
+
+/// Implement the `Event` for a module.
+///
+/// # Simple Event Example:
+///
+/// ```rust
+/// palette_support::decl_event!(
+///    pub enum Event {
+///       Success,
+///       Failure(String),
+///    }
+/// );
+///
+///# fn main() {}
+/// ```
+///
+/// # Generic Event Example:
+///
+/// ```rust
+/// trait Trait {
+///     type Balance;
+///     type Token;
+/// }
+///
+/// mod event1 {
+///     // Event that specifies the generic parameter explicitly (`Balance`).
+///     palette_support::decl_event!(
+///        pub enum Event<T> where Balance = <T as super::Trait>::Balance {
+///           Message(Balance),
+///        }
+///     );
+/// }
+///
+/// mod event2 {
+///     // Event that uses the generic parameter `Balance`.
+///     // If no name for the generic parameter is specified explicitly,
+///     // the name will be taken from the type name of the trait.
+///     palette_support::decl_event!(
+///        pub enum Event<T> where <T as super::Trait>::Balance {
+///           Message(Balance),
+///        }
+///     );
+/// }
+///
+/// mod event3 {
+///     // And we even support declaring multiple generic parameters!
+///     palette_support::decl_event!(
+///        pub enum Event<T> where <T as super::Trait>::Balance, <T as super::Trait>::Token {
+///           Message(Balance, Token),
+///        }
+///     );
+/// }
+///
+///# fn main() {}
+/// ```
+///
+/// The syntax for generic events requires the `where`.
+///
+/// # Generic Event with Instance Example:
+///
+/// ```rust
+///# struct DefaultInstance;
+///# trait Instance {}
+///# impl Instance for DefaultInstance {}
+/// trait Trait<I: Instance=DefaultInstance> {
+///     type Balance;
+///     type Token;
+/// }
+///
+/// // For module with instances, DefaultInstance is optional
+/// palette_support::decl_event!(
+///    pub enum Event<T, I: Instance = DefaultInstance> where
+///       <T as Trait>::Balance,
+///       <T as Trait>::Token
+///    {
+///       Message(Balance, Token),
+///    }
+/// );
+///# fn main() {}
+/// ```
+#[macro_export]
+macro_rules! decl_event {
+	(
+		$(#[$attr:meta])*
+		pub enum Event<$evt_generic_param:ident $(, $instance:ident $(: $instantiable:ident)? $( = $event_default_instance:path)? )?> where
+			$( $tt:tt )*
+	) => {
+		$crate::__decl_generic_event!(
+			$( #[ $attr ] )*;
+			$evt_generic_param;
+			$($instance $( = $event_default_instance)? )?;
+			{ $( $tt )* };
+		);
+	};
+	(
+		$(#[$attr:meta])*
+		pub enum Event {
+			$(
+				$events:tt
+			)*
+		}
+	) => {
+		// Workaround for https://github.com/rust-lang/rust/issues/26925 . Remove when sorted.
+		#[derive(
+			Clone, PartialEq, Eq,
+			$crate::codec::Encode,
+			$crate::codec::Decode,
+			$crate::RuntimeDebug,
+		)]
+		/// Events for this module.
+		///
+		$(#[$attr])*
+		pub enum Event {
+			$(
+				$events
+			)*
+		}
+		impl From<Event> for () {
+			fn from(_: Event) -> () { () }
+		}
+		impl Event {
+			#[allow(dead_code)]
+			#[doc(hidden)]
+			pub fn metadata() -> &'static [ $crate::event::EventMetadata ] {
+				$crate::__events_to_metadata!(; $( $events )* )
+			}
+		}
+	}
+}
+
+#[macro_export]
+#[doc(hidden)]
+// This parsing to retrieve last ident on unnamed generic could be improved.
+// but user can still name it if the parsing fails. And improving parsing seems difficult.
+macro_rules! __decl_generic_event {
+	(
+		$(#[$attr:meta])*;
+		$event_generic_param:ident;
+		$($instance:ident $( = $event_default_instance:path)? )?;
+		{ $( $tt:tt )* };
+	) => {
+		$crate::__decl_generic_event!(@format_generic
+			$( #[ $attr ] )*;
+			$event_generic_param;
+			$($instance $( = $event_default_instance)? )?;
+			{ $( $tt )* };
+			{};
+		);
+	};
+	// Finish formatting on an unnamed one
+	(@format_generic
+		$(#[$attr:meta])*;
+		$event_generic_param:ident;
+		$($instance:ident $( = $event_default_instance:path)? )?;
+		{ <$generic:ident as $trait:path>::$trait_type:ident $(,)? { $( $events:tt )* } };
+		{$( $parsed:tt)*};
+	) => {
+		$crate::__decl_generic_event!(@generate
+			$( #[ $attr ] )*;
+			$event_generic_param;
+			$($instance $( = $event_default_instance)? )?;
+			{ $($events)* };
+			{ $($parsed)*, $trait_type = <$generic as $trait>::$trait_type };
+		);
+	};
+	// Finish formatting on a named one
+	(@format_generic
+		$(#[$attr:meta])*;
+		$event_generic_param:ident;
+		$($instance:ident $( = $event_default_instance:path)? )?;
+		{ $generic_rename:ident = $generic_type:ty $(,)? { $( $events:tt )* } };
+		{ $($parsed:tt)* };
+	) => {
+		$crate::__decl_generic_event!(@generate
+			$(#[$attr])*;
+			$event_generic_param;
+			$($instance $( = $event_default_instance)? )?;
+			{ $($events)* };
+			{ $($parsed)*, $generic_rename = $generic_type };
+		);
+	};
+	// Parse named
+	(@format_generic
+		$(#[$attr:meta])*;
+		$event_generic_param:ident;
+		$($instance:ident $( = $event_default_instance:path)? )?;
+		{ $generic_rename:ident = $generic_type:ty, $($rest:tt)* };
+		{$( $parsed:tt)*};
+	) => {
+		$crate::__decl_generic_event!(@format_generic
+			$( #[ $attr ] )*;
+			$event_generic_param;
+			$( $instance $( = $event_default_instance)? )?;
+			{ $($rest)* };
+			{ $($parsed)*, $generic_rename = $generic_type };
+		);
+	};
+	// Parse unnamed
+	(@format_generic
+		$(#[$attr:meta])*;
+		$event_generic_param:ident;
+		$($instance:ident $( = $event_default_instance:path)? )?;
+		{ <$generic:ident as $trait:path>::$trait_type:ident, $($rest:tt)* };
+		{$($parsed:tt)*};
+	) => {
+		$crate::__decl_generic_event!(@format_generic
+			$( #[ $attr ] )*;
+			$event_generic_param;
+			$($instance $( = $event_default_instance)? )?;
+			{ $($rest)* };
+			{ $($parsed)*, $trait_type = <$generic as $trait>::$trait_type };
+		);
+	};
+	// Unnamed type can't be parsed
+	(@format_generic
+		$(#[$attr:meta])*;
+		$event_generic_param:ident;
+		$($instance:ident $( = $event_default_instance:path)? )?;
+		{ $generic_type:ty, $($rest:tt)* };
+		{ $($parsed:tt)* };
+	) => {
+		$crate::__decl_generic_event!(@cannot_parse $generic_type);
+	};
+	// Final unnamed type can't be parsed
+	(@format_generic
+		$(#[$attr:meta])*;
+		$event_generic_param:ident;
+		$($instance:ident $( = $event_default_instance:path)? )?;
+		{ $generic_type:ty { $( $events:tt )* } };
+		{$( $parsed:tt)*};
+	) => {
+		$crate::__decl_generic_event!(@cannot_parse $generic_type);
+	};
+	(@generate
+		$(#[$attr:meta])*;
+		$event_generic_param:ident;
+		$($instance:ident $( = $event_default_instance:path)? )?;
+		{ $( $events:tt )* };
+		{ ,$( $generic_param:ident = $generic_type:ty ),* };
+	) => {
+		/// [`RawEvent`] specialized for the configuration [`Trait`]
+		///
+		/// [`RawEvent`]: enum.RawEvent.html
+		/// [`Trait`]: trait.Trait.html
+		pub type Event<$event_generic_param $(, $instance $( = $event_default_instance)? )?> = RawEvent<$( $generic_type ),* $(, $instance)? >;
+
+		#[derive(
+			Clone, PartialEq, Eq,
+			$crate::codec::Encode,
+			$crate::codec::Decode,
+			$crate::RuntimeDebug,
+		)]
+		/// Events for this module.
+		///
+		$(#[$attr])*
+		pub enum RawEvent<$( $generic_param ),* $(, $instance)? > {
+			$(
+				$events
+			)*
+			$(
+				#[doc(hidden)]
+				#[codec(skip)]
+				PhantomData($crate::rstd::marker::PhantomData<$instance>),
+			)?
+		}
+		impl<$( $generic_param ),* $(, $instance)? > From<RawEvent<$( $generic_param ),* $(, $instance)?>> for () {
+			fn from(_: RawEvent<$( $generic_param ),* $(, $instance)?>) -> () { () }
+		}
+		impl<$( $generic_param ),* $(, $instance)?> RawEvent<$( $generic_param ),* $(, $instance)?> {
+			#[allow(dead_code)]
+			pub fn metadata() -> &'static [$crate::event::EventMetadata] {
+				$crate::__events_to_metadata!(; $( $events )* )
+			}
+		}
+	};
+	(@cannot_parse $ty:ty) => {
+		compile_error!(concat!("The type `", stringify!($ty), "` can't be parsed as an unnamed one, please name it `Name = ", stringify!($ty), "`"));
+	}
+}
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __events_to_metadata {
+	(
+		$( $metadata:expr ),*;
+		$( #[doc = $doc_attr:tt] )*
+		$event:ident $( ( $( $param:path ),* ) )*,
+		$( $rest:tt )*
+	) => {
+		$crate::__events_to_metadata!(
+			$( $metadata, )*
+			$crate::event::EventMetadata {
+				name: $crate::event::DecodeDifferent::Encode(stringify!($event)),
+				arguments: $crate::event::DecodeDifferent::Encode(&[
+					$( $( stringify!($param) ),* )*
+				]),
+				documentation: $crate::event::DecodeDifferent::Encode(&[
+					$( $doc_attr ),*
+				]),
+			};
+			$( $rest )*
+		)
+	};
+	(
+		$( $metadata:expr ),*;
+	) => {
+		&[ $( $metadata ),* ]
+	}
+}
+
+/// Constructs an Event type for a runtime. This is usually called automatically by the
+/// construct_runtime macro.
+#[macro_export]
+macro_rules! impl_outer_event {
+	// Macro transformations (to convert invocations with incomplete parameters to the canonical
+	// form)
+	(
+		$(#[$attr:meta])*
+		pub enum $name:ident for $runtime:ident {
+			$( $rest_event_without_system:tt )*
+		}
+	) => {
+		$crate::impl_outer_event!(
+			$( #[$attr] )*;
+			$name;
+			$runtime;
+			system;
+			Modules { $( $rest_event_without_system )* };
+			;
+		);
+	};
+	(
+		$(#[$attr:meta])*
+		pub enum $name:ident for $runtime:ident where system = $system:ident {
+			$( $rest_event_with_system:tt )*
+		}
+	) => {
+		$crate::impl_outer_event!(
+			$( #[$attr] )*;
+			$name;
+			$runtime;
+			$system;
+			Modules { $( $rest_event_with_system )* };
+			;
+		);
+	};
+	// Generic + Instance
+	(
+		$(#[$attr:meta])*;
+		$name:ident;
+		$runtime:ident;
+		$system:ident;
+		Modules {
+			$module:ident $instance:ident<T>,
+			$( $rest_event_generic_instance:tt )*
+		};
+		$( $module_name:ident::Event $( <$generic_param:ident> )? $( { $generic_instance:ident } )?, )*;
+	) => {
+		$crate::impl_outer_event!(
+			$( #[$attr] )*;
+			$name;
+			$runtime;
+			$system;
+			Modules { $( $rest_event_generic_instance )* };
+			$( $module_name::Event $( <$generic_param> )? $( { $generic_instance } )?, )* $module::Event<$runtime>{ $instance },;
+		);
+	};
+	// Instance
+	(
+		$(#[$attr:meta])*;
+		$name:ident;
+		$runtime:ident;
+		$system:ident;
+		Modules {
+			$module:ident $instance:ident,
+			$( $rest_event_instance:tt )*
+		};
+		$( $module_name:ident::Event $( <$generic_param:ident> )? $( { $generic_instance:ident } )?, )*;
+	) => {
+		$crate::impl_outer_event!(
+			$( #[$attr] )*;
+			$name;
+			$runtime;
+			$system;
+			Modules { $( $rest_event_instance )* };
+			$( $module_name::Event $( <$generic_param> )* $( { $generic_instance } )?, )* $module::Event { $instance },;
+		);
+	};
+	// Generic
+	(
+		$(#[$attr:meta])*;
+		$name:ident;
+		$runtime:ident;
+		$system:ident;
+		Modules {
+			$module:ident<T>,
+			$( $rest_event_generic:tt )*
+		};
+		$( $module_name:ident::Event $( <$generic_param:ident> )? $( { $generic_instance:ident } )?, )*;
+	) => {
+		$crate::impl_outer_event!(
+			$( #[$attr] )*;
+			$name;
+			$runtime;
+			$system;
+			Modules { $( $rest_event_generic )* };
+			$( $module_name::Event $( <$generic_param> )? $( { $generic_instance } )?, )* $module::Event<$runtime>,;
+		);
+	};
+	// No Generic and no Instance
+	(
+		$(#[$attr:meta])*;
+		$name:ident;
+		$runtime:ident;
+		$system:ident;
+		Modules {
+			$module:ident,
+			$( $rest_event_no_generic_no_instance:tt )*
+		};
+		$( $module_name:ident::Event $( <$generic_param:ident> )? $( { $generic_instance:ident } )?, )*;
+	) => {
+		$crate::impl_outer_event!(
+			$( #[$attr] )*;
+			$name;
+			$runtime;
+			$system;
+			Modules { $( $rest_event_no_generic_no_instance )* };
+			$( $module_name::Event $( <$generic_param> )? $( { $generic_instance } )?, )* $module::Event,;
+		);
+	};
+
+	// The main macro expansion that actually renders the Event enum code.
+	(
+		$(#[$attr:meta])*;
+		$name:ident;
+		$runtime:ident;
+		$system:ident;
+		Modules {};
+		$( $module_name:ident::Event $( <$generic_param:ident> )? $( { $generic_instance:ident } )?, )*;
+	) => {
+		$crate::paste::item! {
+			#[derive(
+				Clone, PartialEq, Eq,
+				$crate::codec::Encode,
+				$crate::codec::Decode,
+				$crate::RuntimeDebug,
+			)]
+			$(#[$attr])*
+			#[allow(non_camel_case_types)]
+			pub enum $name {
+				system($system::Event),
+				$(
+					[< $module_name $(_ $generic_instance )? >](
+						$module_name::Event < $( $generic_param )? $(, $module_name::$generic_instance )? >
+					),
+				)*
+			}
+			impl From<$system::Event> for $name {
+				fn from(x: $system::Event) -> Self {
+					$name::system(x)
+				}
+			}
+			$(
+				impl From<$module_name::Event < $( $generic_param, )? $( $module_name::$generic_instance )? >> for $name {
+					fn from(x: $module_name::Event < $( $generic_param, )? $( $module_name::$generic_instance )? >) -> Self {
+						$name::[< $module_name $(_ $generic_instance )? >](x)
+					}
+				}
+				impl $crate::rstd::convert::TryInto<
+					$module_name::Event < $( $generic_param, )? $( $module_name::$generic_instance )? >
+				> for $name {
+					type Error = ();
+
+					fn try_into(self) -> $crate::rstd::result::Result<
+						$module_name::Event < $( $generic_param, )? $( $module_name::$generic_instance )? >, Self::Error
+					> {
+						match self {
+							Self::[< $module_name $(_ $generic_instance )? >](evt) => Ok(evt),
+							_ => Err(()),
+						}
+					}
+				}
+			)*
+		}
+		$crate::__impl_outer_event_json_metadata!(
+			$runtime;
+			$name;
+			$system;
+			$(
+				$module_name::Event
+				< $( $generic_param )? $(, $module_name::$generic_instance )? >
+				$( $generic_instance )?,
+			)*;
+		);
+	}
+}
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __impl_outer_event_json_metadata {
+	(
+		$runtime:ident;
+		$event_name:ident;
+		$system:ident;
+		$( $module_name:ident::Event < $( $generic_params:path ),* > $( $instance:ident )?, )*;
+	) => {
+		impl $runtime {
+			#[allow(dead_code)]
+			pub fn outer_event_metadata() -> $crate::event::OuterEventMetadata {
+				$crate::event::OuterEventMetadata {
+					name: $crate::event::DecodeDifferent::Encode(stringify!($event_name)),
+					events: $crate::event::DecodeDifferent::Encode(&[
+						("system", $crate::event::FnEncode(system::Event::metadata))
+						$(
+							, (
+								stringify!($module_name),
+								$crate::event::FnEncode(
+									$module_name::Event ::< $( $generic_params ),* > ::metadata
+								)
+							)
+						)*
+					])
+				}
+			}
+			#[allow(dead_code)]
+			pub fn __module_events_system() -> &'static [$crate::event::EventMetadata] {
+				system::Event::metadata()
+			}
+
+			$crate::paste::item! {
+				$(
+					#[allow(dead_code)]
+					pub fn [< __module_events_ $module_name $( _ $instance )? >] () ->
+						&'static [$crate::event::EventMetadata]
+					{
+						$module_name::Event ::< $( $generic_params ),* > ::metadata()
+					}
+				)*
+			}
+		}
+	}
+}
+
+#[cfg(test)]
+#[allow(dead_code)]
+mod tests {
+	use super::*;
+	use serde::Serialize;
+	use codec::{Encode, Decode};
+
+	mod system {
+		pub trait Trait {
+			type Origin;
+			type BlockNumber;
+		}
+
+		decl_module! {
+			pub struct Module<T: Trait> for enum Call where origin: T::Origin {}
+		}
+
+		decl_event!(
+			pub enum Event {
+				SystemEvent,
+			}
+		);
+	}
+
+	mod system_renamed {
+		pub trait Trait {
+			type Origin;
+			type BlockNumber;
+		}
+
+		decl_module! {
+			pub struct Module<T: Trait> for enum Call where origin: T::Origin {}
+		}
+
+		decl_event!(
+			pub enum Event {
+				SystemEvent,
+			}
+		);
+	}
+
+	mod event_module {
+		pub trait Trait {
+			type Origin;
+			type Balance;
+			type BlockNumber;
+		}
+
+		decl_module! {
+			pub struct Module<T: Trait> for enum Call where origin: T::Origin {}
+		}
+
+		decl_event!(
+			/// Event without renaming the generic parameter `Balance` and `Origin`.
+			pub enum Event<T> where <T as Trait>::Balance, <T as Trait>::Origin
+			{
+				/// Hi, I am a comment.
+				TestEvent(Balance, Origin),
+				/// Dog
+				EventWithoutParams,
+			}
+		);
+	}
+
+	mod event_module2 {
+		pub trait Trait {
+			type Origin;
+			type Balance;
+			type BlockNumber;
+		}
+
+		decl_module! {
+			pub struct Module<T: Trait> for enum Call where origin: T::Origin {}
+		}
+
+		decl_event!(
+			/// Event with renamed generic parameter
+			pub enum Event<T> where
+				BalanceRenamed = <T as Trait>::Balance,
+				OriginRenamed = <T as Trait>::Origin
+			{
+				TestEvent(BalanceRenamed),
+				TestOrigin(OriginRenamed),
+			}
+		);
+	}
+
+	mod event_module3 {
+		decl_event!(
+			pub enum Event {
+				HiEvent,
+			}
+		);
+	}
+
+	mod event_module4 {
+		pub trait Trait {
+			type Origin;
+			type Balance;
+			type BlockNumber;
+		}
+
+		decl_module! {
+			pub struct Module<T: Trait> for enum Call where origin: T::Origin {}
+		}
+
+		decl_event!(
+			/// Event finish formatting on an unnamed one with trailling comma
+			pub enum Event<T> where
+				<T as Trait>::Balance,
+				<T as Trait>::Origin,
+			{
+				TestEvent(Balance, Origin),
+			}
+		);
+	}
+
+	mod event_module5 {
+		pub trait Trait {
+			type Origin;
+			type Balance;
+			type BlockNumber;
+		}
+
+		decl_module! {
+			pub struct Module<T: Trait> for enum Call where origin: T::Origin {}
+		}
+
+		decl_event!(
+			/// Event finish formatting on an named one with trailing comma
+			pub enum Event<T> where
+				BalanceRenamed = <T as Trait>::Balance,
+				OriginRenamed = <T as Trait>::Origin,
+			{
+				TestEvent(BalanceRenamed, OriginRenamed),
+			}
+		);
+	}
+
+	#[derive(Debug, Clone, PartialEq, Eq, Encode, Decode, Serialize)]
+	pub struct TestRuntime;
+
+	impl_outer_event! {
+		pub enum TestEvent for TestRuntime {
+			event_module<T>,
+			event_module2<T>,
+			event_module3,
+		}
+	}
+
+	#[derive(Debug, Clone, PartialEq, Eq, Encode, Decode, Serialize)]
+	pub struct TestRuntime2;
+
+	impl_outer_event! {
+		pub enum TestEventSystemRenamed for TestRuntime2 where system = system_renamed {
+			event_module<T>,
+			event_module2<T>,
+			event_module3,
+		}
+	}
+
+	impl event_module::Trait for TestRuntime {
+		type Origin = u32;
+		type Balance = u32;
+		type BlockNumber = u32;
+	}
+
+	impl event_module2::Trait for TestRuntime {
+		type Origin = u32;
+		type Balance = u32;
+		type BlockNumber = u32;
+	}
+
+	impl system::Trait for TestRuntime {
+		type Origin = u32;
+		type BlockNumber = u32;
+	}
+
+	impl event_module::Trait for TestRuntime2 {
+		type Origin = u32;
+		type Balance = u32;
+		type BlockNumber = u32;
+	}
+
+	impl event_module2::Trait for TestRuntime2 {
+		type Origin = u32;
+		type Balance = u32;
+		type BlockNumber = u32;
+	}
+
+	impl system_renamed::Trait for TestRuntime2 {
+		type Origin = u32;
+		type BlockNumber = u32;
+	}
+
+	const EXPECTED_METADATA: OuterEventMetadata = OuterEventMetadata {
+		name: DecodeDifferent::Encode("TestEvent"),
+		events: DecodeDifferent::Encode(&[
+			(
+				"system",
+				FnEncode(|| &[
+					EventMetadata {
+						name: DecodeDifferent::Encode("SystemEvent"),
+						arguments: DecodeDifferent::Encode(&[]),
+						documentation: DecodeDifferent::Encode(&[]),
+					}
+				])
+			),
+			(
+				"event_module",
+				FnEncode(|| &[
+					EventMetadata {
+						name: DecodeDifferent::Encode("TestEvent"),
+						arguments: DecodeDifferent::Encode(&[ "Balance", "Origin" ]),
+						documentation: DecodeDifferent::Encode(&[ " Hi, I am a comment." ])
+					},
+					EventMetadata {
+						name: DecodeDifferent::Encode("EventWithoutParams"),
+						arguments: DecodeDifferent::Encode(&[]),
+						documentation: DecodeDifferent::Encode(&[ " Dog" ]),
+					},
+				])
+			),
+			(
+				"event_module2",
+				FnEncode(|| &[
+					EventMetadata {
+						name: DecodeDifferent::Encode("TestEvent"),
+						arguments: DecodeDifferent::Encode(&[ "BalanceRenamed" ]),
+						documentation: DecodeDifferent::Encode(&[])
+					},
+					EventMetadata {
+						name: DecodeDifferent::Encode("TestOrigin"),
+						arguments: DecodeDifferent::Encode(&[ "OriginRenamed" ]),
+						documentation: DecodeDifferent::Encode(&[]),
+					},
+				])
+			),
+			(
+				"event_module3",
+				FnEncode(|| &[
+					EventMetadata {
+						name: DecodeDifferent::Encode("HiEvent"),
+						arguments: DecodeDifferent::Encode(&[]),
+						documentation: DecodeDifferent::Encode(&[])
+					}
+				])
+			)
+		])
+	};
+
+	#[test]
+	fn outer_event_metadata() {
+		assert_eq!(EXPECTED_METADATA, TestRuntime::outer_event_metadata());
+	}
+}

substrate/palette/support/src/hash.rs

@@ -0,0 +1,114 @@
+// Copyright 2017-2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Hash utilities.
+
+use codec::Codec;
+use rstd::prelude::Vec;
+use runtime_io::hashing::{blake2_128, blake2_256, twox_64, twox_128, twox_256};
+
+// This trait must be kept coherent with palette-support-procedural HasherKind usage
+pub trait Hashable: Sized {
+	fn blake2_128(&self) -> [u8; 16];
+	fn blake2_256(&self) -> [u8; 32];
+	fn twox_128(&self) -> [u8; 16];
+	fn twox_256(&self) -> [u8; 32];
+	fn twox_64_concat(&self) -> Vec<u8>;
+}
+
+impl<T: Codec> Hashable for T {
+	fn blake2_128(&self) -> [u8; 16] {
+		self.using_encoded(blake2_128)
+	}
+	fn blake2_256(&self) -> [u8; 32] {
+		self.using_encoded(blake2_256)
+	}
+	fn twox_128(&self) -> [u8; 16] {
+		self.using_encoded(twox_128)
+	}
+	fn twox_256(&self) -> [u8; 32] {
+		self.using_encoded(twox_256)
+	}
+	fn twox_64_concat(&self) -> Vec<u8> {
+		self.using_encoded(Twox64Concat::hash)
+	}
+}
+
+/// Hasher to use to hash keys to insert to storage.
+pub trait StorageHasher: 'static {
+	type Output: AsRef<[u8]>;
+	fn hash(x: &[u8]) -> Self::Output;
+}
+
+/// Hash storage keys with `concat(twox64(key), key)`
+pub struct Twox64Concat;
+impl StorageHasher for Twox64Concat {
+	type Output = Vec<u8>;
+	fn hash(x: &[u8]) -> Vec<u8> {
+		twox_64(x)
+			.iter()
+			.chain(x.into_iter())
+			.cloned()
+			.collect::<Vec<_>>()
+	}
+}
+
+/// Hash storage keys with blake2 128
+pub struct Blake2_128;
+impl StorageHasher for Blake2_128 {
+	type Output = [u8; 16];
+	fn hash(x: &[u8]) -> [u8; 16] {
+		blake2_128(x)
+	}
+}
+
+/// Hash storage keys with blake2 256
+pub struct Blake2_256;
+impl StorageHasher for Blake2_256 {
+	type Output = [u8; 32];
+	fn hash(x: &[u8]) -> [u8; 32] {
+		blake2_256(x)
+	}
+}
+
+/// Hash storage keys with twox 128
+pub struct Twox128;
+impl StorageHasher for Twox128 {
+	type Output = [u8; 16];
+	fn hash(x: &[u8]) -> [u8; 16] {
+		twox_128(x)
+	}
+}
+
+/// Hash storage keys with twox 256
+pub struct Twox256;
+impl StorageHasher for Twox256 {
+	type Output = [u8; 32];
+	fn hash(x: &[u8]) -> [u8; 32] {
+		twox_256(x)
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	#[test]
+	fn test_twox_64_concat() {
+		let r = Twox64Concat::hash(b"foo");
+		assert_eq!(r.split_at(8), (&twox_128(b"foo")[..8], &b"foo"[..]))
+	}
+}

substrate/palette/support/src/inherent.rs

@@ -0,0 +1,104 @@
+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+#[doc(hidden)]
+pub use crate::rstd::vec::Vec;
+#[doc(hidden)]
+pub use crate::sr_primitives::traits::{Block as BlockT, Extrinsic};
+#[doc(hidden)]
+pub use inherents::{InherentData, ProvideInherent, CheckInherentsResult, IsFatalError};
+
+
+/// Implement the outer inherent.
+/// All given modules need to implement `ProvideInherent`.
+///
+/// # Example
+///
+/// ```nocompile
+/// impl_outer_inherent! {
+///     impl Inherents where Block = Block, UncheckedExtrinsic = UncheckedExtrinsic {
+///         timestamp: Timestamp,
+///         consensus: Consensus,
+///         /// Aura module using the `Timestamp` call.
+///         aura: Timestamp,
+///     }
+/// }
+/// ```
+#[macro_export]
+macro_rules! impl_outer_inherent {
+	(
+		impl Inherents where Block = $block:ident, UncheckedExtrinsic = $uncheckedextrinsic:ident
+		{
+			$( $module:ident: $call:ident, )*
+		}
+	) => {
+		trait InherentDataExt {
+			fn create_extrinsics(&self) ->
+				$crate::inherent::Vec<<$block as $crate::inherent::BlockT>::Extrinsic>;
+			fn check_extrinsics(&self, block: &$block) -> $crate::inherent::CheckInherentsResult;
+		}
+
+		impl InherentDataExt for $crate::inherent::InherentData {
+			fn create_extrinsics(&self) ->
+				$crate::inherent::Vec<<$block as $crate::inherent::BlockT>::Extrinsic> {
+				use $crate::inherent::ProvideInherent;
+				use $crate::inherent::Extrinsic;
+
+				let mut inherents = Vec::new();
+
+				$(
+					if let Some(inherent) = $module::create_inherent(self) {
+						inherents.push($uncheckedextrinsic::new(
+							Call::$call(inherent),
+							None,
+						).expect("Runtime UncheckedExtrinsic is not Opaque, so it has to return `Some`; qed"));
+					}
+				)*
+
+				inherents
+			}
+
+			fn check_extrinsics(&self, block: &$block) -> $crate::inherent::CheckInherentsResult {
+				use $crate::inherent::{ProvideInherent, IsFatalError};
+
+				let mut result = $crate::inherent::CheckInherentsResult::new();
+				for xt in block.extrinsics() {
+					if $crate::inherent::Extrinsic::is_signed(xt).unwrap_or(false) {
+						break;
+					}
+
+					$(
+						match xt.function {
+							Call::$call(ref call) => {
+								if let Err(e) = $module::check_inherent(call, self) {
+									result.put_error(
+										$module::INHERENT_IDENTIFIER, &e
+									).expect("There is only one fatal error; qed");
+									if e.is_fatal_error() {
+										return result;
+									}
+								}
+							}
+							_ => {},
+						}
+					)*
+				}
+
+				result
+			}
+		}
+	};
+}

substrate/palette/support/src/lib.rs

@@ -0,0 +1,605 @@
+// Copyright 2017-2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Support code for the runtime.
+
+#![cfg_attr(not(feature = "std"), no_std)]
+
+/// Export ourself as `palette_support` to make tests happy.
+extern crate self as palette_support;
+
+#[macro_use]
+extern crate bitmask;
+
+#[cfg(feature = "std")]
+pub use serde;
+#[doc(hidden)]
+pub use rstd;
+#[doc(hidden)]
+pub use codec;
+#[cfg(feature = "std")]
+#[doc(hidden)]
+pub use once_cell;
+#[doc(hidden)]
+pub use paste;
+#[cfg(feature = "std")]
+#[doc(hidden)]
+pub use state_machine::BasicExternalities;
+#[doc(hidden)]
+pub use runtime_io::storage::root as storage_root;
+#[doc(hidden)]
+pub use sr_primitives::RuntimeDebug;
+
+#[macro_use]
+pub mod debug;
+#[macro_use]
+pub mod dispatch;
+pub mod storage;
+mod hash;
+#[macro_use]
+pub mod event;
+#[macro_use]
+mod origin;
+#[macro_use]
+pub mod metadata;
+#[macro_use]
+mod runtime;
+#[macro_use]
+pub mod inherent;
+#[macro_use]
+pub mod unsigned;
+#[macro_use]
+pub mod error;
+pub mod traits;
+
+pub use self::hash::{Twox256, Twox128, Blake2_256, Blake2_128, Twox64Concat, Hashable};
+pub use self::storage::{StorageValue, StorageMap, StorageLinkedMap, StorageDoubleMap};
+pub use self::dispatch::{Parameter, Callable, IsSubType};
+pub use sr_primitives::{self, ConsensusEngineId, print, traits::Printable};
+
+/// Macro for easily creating a new implementation of the `Get` trait. Use similarly to
+/// how you would declare a `const`:
+///
+/// ```no_compile
+/// parameter_types! {
+///   pub const Argument: u64 = 42;
+/// }
+/// trait Config {
+///   type Parameter: Get<u64>;
+/// }
+/// struct Runtime;
+/// impl Config for Runtime {
+///   type Parameter = Argument;
+/// }
+/// ```
+#[macro_export]
+macro_rules! parameter_types {
+	(
+		$( #[ $attr:meta ] )*
+		$vis:vis const $name:ident: $type:ty = $value:expr;
+		$( $rest:tt )*
+	) => (
+		$( #[ $attr ] )*
+		$vis struct $name;
+		$crate::parameter_types!{IMPL $name , $type , $value}
+		$crate::parameter_types!{ $( $rest )* }
+	);
+	() => ();
+	(IMPL $name:ident , $type:ty , $value:expr) => {
+		impl $name {
+			pub fn get() -> $type {
+				$value
+			}
+		}
+		impl<I: From<$type>> $crate::traits::Get<I> for $name {
+			fn get() -> I {
+				I::from($value)
+			}
+		}
+	}
+}
+
+#[doc(inline)]
+pub use palette_support_procedural::decl_storage;
+
+/// Return Err of the expression: `return Err($expression);`.
+///
+/// Used as `fail!(expression)`.
+#[macro_export]
+macro_rules! fail {
+	( $y:expr ) => {{
+		return Err($y);
+	}}
+}
+
+/// Evaluate `$x:expr` and if not true return `Err($y:expr)`.
+///
+/// Used as `ensure!(expression_to_ensure, expression_to_return_on_false)`.
+#[macro_export]
+macro_rules! ensure {
+	( $x:expr, $y:expr $(,)? ) => {{
+		if !$x {
+			$crate::fail!($y);
+		}
+	}}
+}
+
+/// Evaluate an expression, assert it returns an expected `Err` value and that
+/// runtime storage has not been mutated (i.e. expression is a no-operation).
+///
+/// Used as `assert_noop(expression_to_assert, expected_error_expression)`.
+#[macro_export]
+#[cfg(feature = "std")]
+macro_rules! assert_noop {
+	(
+		$x:expr,
+		$y:expr $(,)?
+	) => {
+		let h = $crate::storage_root();
+		$crate::assert_err!($x, $y);
+		assert_eq!(h, $crate::storage_root());
+	}
+}
+
+/// Panic if an expression doesn't evaluate to an `Err`.
+///
+/// Used as `assert_err!(expression_to_assert, expected_err_expression)`.
+
+/// Assert an expression returns an error specified.
+///
+/// Used as `assert_err!(expression_to_assert, expected_error_expression)`
+#[macro_export]
+#[cfg(feature = "std")]
+macro_rules! assert_err {
+	( $x:expr , $y:expr $(,)? ) => {
+		assert_eq!($x, Err($y));
+	}
+}
+
+/// Panic if an expression doesn't evaluate to `Ok`.
+///
+/// Used as `assert_ok!(expression_to_assert, expected_ok_expression)`,
+/// or `assert_ok!(expression_to_assert)` which would assert against `Ok(())`.
+#[macro_export]
+#[cfg(feature = "std")]
+macro_rules! assert_ok {
+	( $x:expr $(,)? ) => {
+		assert_eq!($x, Ok(()));
+	};
+	( $x:expr, $y:expr $(,)? ) => {
+		assert_eq!($x, Ok($y));
+	}
+}
+
+/// Panic when the vectors are different, without taking the order into account.
+///
+/// # Examples
+///
+/// ```rust
+/// #[macro_use]
+/// # extern crate palette_support;
+/// # use palette_support::{assert_eq_uvec};
+/// # fn main() {
+/// assert_eq_uvec!(vec![1,2], vec![2,1]);
+/// # }
+/// ```
+///
+/// ```rust,should_panic
+/// #[macro_use]
+/// # extern crate palette_support;
+/// # use palette_support::{assert_eq_uvec};
+/// # fn main() {
+/// assert_eq_uvec!(vec![1,2,3], vec![2,1]);
+/// # }
+/// ```
+#[macro_export]
+#[cfg(feature = "std")]
+macro_rules! assert_eq_uvec {
+	( $x:expr, $y:expr ) => {
+		$crate::__assert_eq_uvec!($x, $y);
+		$crate::__assert_eq_uvec!($y, $x);
+	}
+}
+
+#[macro_export]
+#[doc(hidden)]
+#[cfg(feature = "std")]
+macro_rules! __assert_eq_uvec {
+	( $x:expr, $y:expr ) => {
+		$x.iter().for_each(|e| {
+			if !$y.contains(e) { panic!(format!("vectors not equal: {:?} != {:?}", $x, $y)); }
+		});
+	}
+}
+
+/// The void type - it cannot exist.
+// Oh rust, you crack me up...
+#[derive(Clone, Eq, PartialEq, RuntimeDebug)]
+pub enum Void {}
+
+#[cfg(feature = "std")]
+#[doc(hidden)]
+pub use serde::{Serialize, Deserialize};
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+	use codec::{Codec, EncodeLike};
+	use palette_metadata::{
+		DecodeDifferent, StorageEntryMetadata, StorageMetadata, StorageEntryType,
+		StorageEntryModifier, DefaultByteGetter, StorageHasher,
+	};
+	use rstd::marker::PhantomData;
+
+	pub trait Trait {
+		type BlockNumber: Codec + EncodeLike + Default;
+		type Origin;
+	}
+
+	mod module {
+		#![allow(dead_code)]
+
+		use super::Trait;
+
+		decl_module! {
+			pub struct Module<T: Trait> for enum Call where origin: T::Origin {}
+		}
+	}
+	use self::module::Module;
+
+	decl_storage! {
+		trait Store for Module<T: Trait> as Example {
+			pub Data get(fn data) build(|_| vec![(15u32, 42u64)]):
+				linked_map hasher(twox_64_concat) u32 => u64;
+			pub OptionLinkedMap: linked_map u32 => Option<u32>;
+			pub GenericData get(fn generic_data):
+				linked_map hasher(twox_128) T::BlockNumber => T::BlockNumber;
+			pub GenericData2 get(fn generic_data2):
+				linked_map T::BlockNumber => Option<T::BlockNumber>;
+			pub GetterNoFnKeyword get(no_fn): Option<u32>;
+
+			pub DataDM config(test_config) build(|_| vec![(15u32, 16u32, 42u64)]):
+				double_map hasher(twox_64_concat) u32, blake2_256(u32) => u64;
+			pub GenericDataDM:
+				double_map T::BlockNumber, twox_128(T::BlockNumber) => T::BlockNumber;
+			pub GenericData2DM:
+				double_map T::BlockNumber, twox_256(T::BlockNumber) => Option<T::BlockNumber>;
+			pub AppendableDM: double_map u32, blake2_256(T::BlockNumber) => Vec<u32>;
+		}
+	}
+
+	struct Test;
+	impl Trait for Test {
+		type BlockNumber = u32;
+		type Origin = u32;
+	}
+
+	fn new_test_ext() -> runtime_io::TestExternalities {
+		GenesisConfig::default().build_storage().unwrap().into()
+	}
+
+	type Map = Data;
+
+	#[test]
+	fn linked_map_issue_3318() {
+		new_test_ext().execute_with(|| {
+			OptionLinkedMap::insert(1, 1);
+			assert_eq!(OptionLinkedMap::get(1), Some(1));
+			OptionLinkedMap::insert(1, 2);
+			assert_eq!(OptionLinkedMap::get(1), Some(2));
+		});
+	}
+
+	#[test]
+	fn linked_map_swap_works() {
+		new_test_ext().execute_with(|| {
+			OptionLinkedMap::insert(0, 0);
+			OptionLinkedMap::insert(1, 1);
+			OptionLinkedMap::insert(2, 2);
+			OptionLinkedMap::insert(3, 3);
+
+			let collect = || OptionLinkedMap::enumerate().collect::<Vec<_>>();
+			assert_eq!(collect(), vec![(3, 3), (2, 2), (1, 1), (0, 0)]);
+
+			// Two existing
+			OptionLinkedMap::swap(1, 2);
+			assert_eq!(collect(), vec![(3, 3), (2, 1), (1, 2), (0, 0)]);
+
+			// Back to normal
+			OptionLinkedMap::swap(2, 1);
+			assert_eq!(collect(), vec![(3, 3), (2, 2), (1, 1), (0, 0)]);
+
+			// Left existing
+			OptionLinkedMap::swap(2, 5);
+			assert_eq!(collect(), vec![(5, 2), (3, 3), (1, 1), (0, 0)]);
+
+			// Right existing
+			OptionLinkedMap::swap(5, 2);
+			assert_eq!(collect(), vec![(2, 2), (3, 3), (1, 1), (0, 0)]);
+		});
+	}
+
+	#[test]
+	fn linked_map_basic_insert_remove_should_work() {
+		new_test_ext().execute_with(|| {
+			// initialized during genesis
+			assert_eq!(Map::get(&15u32), 42u64);
+
+			// get / insert / take
+			let key = 17u32;
+			assert_eq!(Map::get(&key), 0u64);
+			Map::insert(key, 4u64);
+			assert_eq!(Map::get(&key), 4u64);
+			assert_eq!(Map::take(&key), 4u64);
+			assert_eq!(Map::get(&key), 0u64);
+
+			// mutate
+			Map::mutate(&key, |val| {
+				*val = 15;
+			});
+			assert_eq!(Map::get(&key), 15u64);
+
+			// remove
+			Map::remove(&key);
+			assert_eq!(Map::get(&key), 0u64);
+		});
+	}
+
+	#[test]
+	fn linked_map_enumeration_and_head_should_work() {
+		new_test_ext().execute_with(|| {
+			assert_eq!(Map::head(), Some(15));
+			assert_eq!(Map::enumerate().collect::<Vec<_>>(), vec![(15, 42)]);
+			// insert / remove
+			let key = 17u32;
+			Map::insert(key, 4u64);
+			assert_eq!(Map::head(), Some(key));
+			assert_eq!(Map::enumerate().collect::<Vec<_>>(), vec![(key, 4), (15, 42)]);
+			assert_eq!(Map::take(&15), 42u64);
+			assert_eq!(Map::take(&key), 4u64);
+			assert_eq!(Map::head(), None);
+			assert_eq!(Map::enumerate().collect::<Vec<_>>(), vec![]);
+
+			// Add couple of more elements
+			Map::insert(key, 42u64);
+			assert_eq!(Map::head(), Some(key));
+			assert_eq!(Map::enumerate().collect::<Vec<_>>(), vec![(key, 42)]);
+			Map::insert(key + 1, 43u64);
+			assert_eq!(Map::head(), Some(key + 1));
+			assert_eq!(Map::enumerate().collect::<Vec<_>>(), vec![(key + 1, 43), (key, 42)]);
+
+			// mutate
+			let key = key + 2;
+			Map::mutate(&key, |val| {
+				*val = 15;
+			});
+			assert_eq!(Map::enumerate().collect::<Vec<_>>(), vec![(key, 15), (key - 1, 43), (key - 2, 42)]);
+			assert_eq!(Map::head(), Some(key));
+			Map::mutate(&key, |val| {
+				*val = 17;
+			});
+			assert_eq!(Map::enumerate().collect::<Vec<_>>(), vec![(key, 17), (key - 1, 43), (key - 2, 42)]);
+
+			// remove first
+			Map::remove(&key);
+			assert_eq!(Map::head(), Some(key - 1));
+			assert_eq!(Map::enumerate().collect::<Vec<_>>(), vec![(key - 1, 43), (key - 2, 42)]);
+
+			// remove last from the list
+			Map::remove(&(key - 2));
+			assert_eq!(Map::head(), Some(key - 1));
+			assert_eq!(Map::enumerate().collect::<Vec<_>>(), vec![(key - 1, 43)]);
+
+			// remove the last element
+			Map::remove(&(key - 1));
+			assert_eq!(Map::head(), None);
+			assert_eq!(Map::enumerate().collect::<Vec<_>>(), vec![]);
+		});
+	}
+
+	#[test]
+	fn double_map_basic_insert_remove_remove_prefix_should_work() {
+		new_test_ext().execute_with(|| {
+			type DoubleMap = DataDM;
+			// initialized during genesis
+			assert_eq!(DoubleMap::get(&15u32, &16u32), 42u64);
+
+			// get / insert / take
+			let key1 = 17u32;
+			let key2 = 18u32;
+			assert_eq!(DoubleMap::get(&key1, &key2), 0u64);
+			DoubleMap::insert(&key1, &key2, &4u64);
+			assert_eq!(DoubleMap::get(&key1, &key2), 4u64);
+			assert_eq!(DoubleMap::take(&key1, &key2), 4u64);
+			assert_eq!(DoubleMap::get(&key1, &key2), 0u64);
+
+			// mutate
+			DoubleMap::mutate(&key1, &key2, |val| {
+				*val = 15;
+			});
+			assert_eq!(DoubleMap::get(&key1, &key2), 15u64);
+
+			// remove
+			DoubleMap::remove(&key1, &key2);
+			assert_eq!(DoubleMap::get(&key1, &key2), 0u64);
+
+			// remove prefix
+			DoubleMap::insert(&key1, &key2, &4u64);
+			DoubleMap::insert(&key1, &(key2 + 1), &4u64);
+			DoubleMap::insert(&(key1 + 1), &key2, &4u64);
+			DoubleMap::insert(&(key1 + 1), &(key2 + 1), &4u64);
+			DoubleMap::remove_prefix(&key1);
+			assert_eq!(DoubleMap::get(&key1, &key2), 0u64);
+			assert_eq!(DoubleMap::get(&key1, &(key2 + 1)), 0u64);
+			assert_eq!(DoubleMap::get(&(key1 + 1), &key2), 4u64);
+			assert_eq!(DoubleMap::get(&(key1 + 1), &(key2 + 1)), 4u64);
+
+		});
+	}
+
+	#[test]
+	fn double_map_append_should_work() {
+		new_test_ext().execute_with(|| {
+			type DoubleMap = AppendableDM<Test>;
+
+			let key1 = 17u32;
+			let key2 = 18u32;
+
+			DoubleMap::insert(&key1, &key2, &vec![1]);
+			DoubleMap::append(&key1, &key2, &[2, 3]).unwrap();
+			assert_eq!(DoubleMap::get(&key1, &key2), &[1, 2, 3]);
+		});
+	}
+
+	const EXPECTED_METADATA: StorageMetadata = StorageMetadata {
+		prefix: DecodeDifferent::Encode("Example"),
+		entries: DecodeDifferent::Encode(
+			&[
+				StorageEntryMetadata {
+					name: DecodeDifferent::Encode("Data"),
+					modifier: StorageEntryModifier::Default,
+					ty: StorageEntryType::Map{
+						hasher: StorageHasher::Twox64Concat,
+						key: DecodeDifferent::Encode("u32"),
+						value: DecodeDifferent::Encode("u64"),
+						is_linked: true,
+					},
+					default: DecodeDifferent::Encode(
+						DefaultByteGetter(&__GetByteStructData(PhantomData::<Test>))
+					),
+					documentation: DecodeDifferent::Encode(&[]),
+				},
+				StorageEntryMetadata {
+					name: DecodeDifferent::Encode("OptionLinkedMap"),
+					modifier: StorageEntryModifier::Optional,
+					ty: StorageEntryType::Map {
+						hasher: StorageHasher::Blake2_256,
+						key: DecodeDifferent::Encode("u32"),
+						value: DecodeDifferent::Encode("u32"),
+						is_linked: true,
+					},
+					default: DecodeDifferent::Encode(
+						DefaultByteGetter(&__GetByteStructOptionLinkedMap(PhantomData::<Test>))
+					),
+					documentation: DecodeDifferent::Encode(&[]),
+				},
+				StorageEntryMetadata {
+					name: DecodeDifferent::Encode("GenericData"),
+					modifier: StorageEntryModifier::Default,
+					ty: StorageEntryType::Map{
+						hasher: StorageHasher::Twox128,
+						key: DecodeDifferent::Encode("T::BlockNumber"),
+						value: DecodeDifferent::Encode("T::BlockNumber"),
+						is_linked: true
+					},
+					default: DecodeDifferent::Encode(
+						DefaultByteGetter(&__GetByteStructGenericData(PhantomData::<Test>))
+					),
+					documentation: DecodeDifferent::Encode(&[]),
+				},
+				StorageEntryMetadata {
+					name: DecodeDifferent::Encode("GenericData2"),
+					modifier: StorageEntryModifier::Optional,
+					ty: StorageEntryType::Map{
+						hasher: StorageHasher::Blake2_256,
+						key: DecodeDifferent::Encode("T::BlockNumber"),
+						value: DecodeDifferent::Encode("T::BlockNumber"),
+						is_linked: true
+					},
+					default: DecodeDifferent::Encode(
+						DefaultByteGetter(&__GetByteStructGenericData2(PhantomData::<Test>))
+					),
+					documentation: DecodeDifferent::Encode(&[]),
+				},
+				StorageEntryMetadata {
+					name: DecodeDifferent::Encode("GetterNoFnKeyword"),
+					modifier: StorageEntryModifier::Optional,
+					ty: StorageEntryType::Plain(DecodeDifferent::Encode("u32")),
+					default: DecodeDifferent::Encode(
+						DefaultByteGetter(&__GetByteStructGetterNoFnKeyword(PhantomData::<Test>))
+					),
+					documentation: DecodeDifferent::Encode(&[]),
+				},
+				StorageEntryMetadata {
+					name: DecodeDifferent::Encode("DataDM"),
+					modifier: StorageEntryModifier::Default,
+					ty: StorageEntryType::DoubleMap{
+						hasher: StorageHasher::Twox64Concat,
+						key1: DecodeDifferent::Encode("u32"),
+						key2: DecodeDifferent::Encode("u32"),
+						value: DecodeDifferent::Encode("u64"),
+						key2_hasher: StorageHasher::Blake2_256,
+					},
+					default: DecodeDifferent::Encode(
+						DefaultByteGetter(&__GetByteStructDataDM(PhantomData::<Test>))
+					),
+					documentation: DecodeDifferent::Encode(&[]),
+				},
+				StorageEntryMetadata {
+					name: DecodeDifferent::Encode("GenericDataDM"),
+					modifier: StorageEntryModifier::Default,
+					ty: StorageEntryType::DoubleMap{
+						hasher: StorageHasher::Blake2_256,
+						key1: DecodeDifferent::Encode("T::BlockNumber"),
+						key2: DecodeDifferent::Encode("T::BlockNumber"),
+						value: DecodeDifferent::Encode("T::BlockNumber"),
+						key2_hasher: StorageHasher::Twox128,
+					},
+					default: DecodeDifferent::Encode(
+						DefaultByteGetter(&__GetByteStructGenericDataDM(PhantomData::<Test>))
+					),
+					documentation: DecodeDifferent::Encode(&[]),
+				},
+				StorageEntryMetadata {
+					name: DecodeDifferent::Encode("GenericData2DM"),
+					modifier: StorageEntryModifier::Optional,
+					ty: StorageEntryType::DoubleMap{
+						hasher: StorageHasher::Blake2_256,
+						key1: DecodeDifferent::Encode("T::BlockNumber"),
+						key2: DecodeDifferent::Encode("T::BlockNumber"),
+						value: DecodeDifferent::Encode("T::BlockNumber"),
+						key2_hasher: StorageHasher::Twox256,
+					},
+					default: DecodeDifferent::Encode(
+						DefaultByteGetter(&__GetByteStructGenericData2DM(PhantomData::<Test>))
+					),
+					documentation: DecodeDifferent::Encode(&[]),
+				},
+				StorageEntryMetadata {
+					name: DecodeDifferent::Encode("AppendableDM"),
+					modifier: StorageEntryModifier::Default,
+					ty: StorageEntryType::DoubleMap{
+						hasher: StorageHasher::Blake2_256,
+						key1: DecodeDifferent::Encode("u32"),
+						key2: DecodeDifferent::Encode("T::BlockNumber"),
+						value: DecodeDifferent::Encode("Vec<u32>"),
+						key2_hasher: StorageHasher::Blake2_256,
+					},
+					default: DecodeDifferent::Encode(
+						DefaultByteGetter(&__GetByteStructGenericData2DM(PhantomData::<Test>))
+					),
+					documentation: DecodeDifferent::Encode(&[]),
+				},
+			]
+		),
+	};
+
+	#[test]
+	fn store_metadata() {
+		let metadata = Module::<Test>::storage_metadata();
+		pretty_assertions::assert_eq!(EXPECTED_METADATA, metadata);
+	}
+}

substrate/palette/support/src/metadata.rs

@@ -0,0 +1,553 @@
+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+pub use palette_metadata::{
+	DecodeDifferent, FnEncode, RuntimeMetadata, ModuleMetadata, RuntimeMetadataLastVersion,
+	DefaultByteGetter, RuntimeMetadataPrefixed, StorageEntryMetadata, StorageMetadata,
+	StorageEntryType, StorageEntryModifier, DefaultByte, StorageHasher, ModuleErrorMetadata
+};
+
+/// Implements the metadata support for the given runtime and all its modules.
+///
+/// Example:
+/// ```
+///# mod module0 {
+///#    pub trait Trait {
+///#        type Origin;
+///#        type BlockNumber;
+///#    }
+///#    palette_support::decl_module! {
+///#        pub struct Module<T: Trait> for enum Call where origin: T::Origin {}
+///#    }
+///#
+///#    palette_support::decl_storage! {
+///#        trait Store for Module<T: Trait> as TestStorage {}
+///#    }
+///# }
+///# use module0 as module1;
+///# use module0 as module2;
+///# impl module0::Trait for Runtime {
+///#     type Origin = u32;
+///#     type BlockNumber = u32;
+///# }
+///
+/// struct Runtime;
+/// palette_support::impl_runtime_metadata! {
+///     for Runtime with modules
+///         module0::Module as Module0 with,
+///         module1::Module as Module1 with,
+///         module2::Module as Module2 with Storage,
+/// };
+/// ```
+///
+/// In this example, just `MODULE3` implements the `Storage` trait.
+#[macro_export]
+macro_rules! impl_runtime_metadata {
+	(
+		for $runtime:ident with modules
+			$( $rest:tt )*
+	) => {
+		impl $runtime {
+			pub fn metadata() -> $crate::metadata::RuntimeMetadataPrefixed {
+				$crate::metadata::RuntimeMetadataLastVersion {
+						modules: $crate::__runtime_modules_to_metadata!($runtime;; $( $rest )*),
+				}.into()
+			}
+		}
+	}
+}
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __runtime_modules_to_metadata {
+	(
+		$runtime: ident;
+		$( $metadata:expr ),*;
+		$mod:ident::$module:ident $( < $instance:ident > )? as $name:ident $(with)+ $($kw:ident)*,
+		$( $rest:tt )*
+	) => {
+		$crate::__runtime_modules_to_metadata!(
+			$runtime;
+			$( $metadata, )* $crate::metadata::ModuleMetadata {
+				name: $crate::metadata::DecodeDifferent::Encode(stringify!($name)),
+				storage: $crate::__runtime_modules_to_metadata_calls_storage!(
+					$mod, $module $( <$instance> )?, $runtime, $(with $kw)*
+				),
+				calls: $crate::__runtime_modules_to_metadata_calls_call!(
+					$mod, $module $( <$instance> )?, $runtime, $(with $kw)*
+				),
+				event: $crate::__runtime_modules_to_metadata_calls_event!(
+					$mod, $module $( <$instance> )?, $runtime, $(with $kw)*
+				),
+				constants: $crate::metadata::DecodeDifferent::Encode(
+					$crate::metadata::FnEncode(
+						$mod::$module::<$runtime $(, $mod::$instance )?>::module_constants_metadata
+					)
+				),
+				errors: $crate::metadata::DecodeDifferent::Encode(
+					$crate::metadata::FnEncode(
+						<$mod::$module::<$runtime $(, $mod::$instance )?> as $crate::metadata::ModuleErrorMetadata>::metadata
+					)
+				)
+			};
+			$( $rest )*
+		)
+	};
+	(
+		$runtime:ident;
+		$( $metadata:expr ),*;
+	) => {
+		$crate::metadata::DecodeDifferent::Encode(&[ $( $metadata ),* ])
+	};
+}
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __runtime_modules_to_metadata_calls_call {
+	(
+		$mod: ident,
+		$module: ident $( <$instance:ident> )?,
+		$runtime: ident,
+		with Call
+		$(with $kws:ident)*
+	) => {
+		Some($crate::metadata::DecodeDifferent::Encode(
+			$crate::metadata::FnEncode(
+				$mod::$module::<$runtime $(, $mod::$instance )?>::call_functions
+			)
+		))
+	};
+	(
+		$mod: ident,
+		$module: ident $( <$instance:ident> )?,
+		$runtime: ident,
+		with $_:ident
+		$(with $kws:ident)*
+	) => {
+		$crate::__runtime_modules_to_metadata_calls_call! {
+			$mod, $module $( <$instance> )?, $runtime, $(with $kws)*
+		};
+	};
+	(
+		$mod: ident,
+		$module: ident $( <$instance:ident> )?,
+		$runtime: ident,
+	) => {
+		None
+	};
+}
+
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __runtime_modules_to_metadata_calls_event {
+	(
+		$mod: ident,
+		$module: ident $( <$instance:ident> )?,
+		$runtime: ident,
+		with Event
+		$(with $kws:ident)*
+	) => {
+		Some($crate::metadata::DecodeDifferent::Encode(
+			$crate::metadata::FnEncode(
+				$crate::paste::expr!{
+					$runtime:: [< __module_events_ $mod $(_ $instance)?>]
+				}
+			)
+		))
+	};
+	(
+		$mod: ident,
+		$module: ident $( <$instance:ident> )?,
+		$runtime: ident,
+		with $_:ident
+		$(with $kws:ident)*
+	) => {
+		$crate::__runtime_modules_to_metadata_calls_event!( $mod, $module $( <$instance> )?, $runtime, $(with $kws)* );
+	};
+	(
+		$mod: ident,
+		$module: ident $( <$instance:ident> )?,
+		$runtime: ident,
+	) => {
+		None
+	};
+}
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __runtime_modules_to_metadata_calls_storage {
+	(
+		$mod: ident,
+		$module: ident $( <$instance:ident> )?,
+		$runtime: ident,
+		with Storage
+		$(with $kws:ident)*
+	) => {
+		Some($crate::metadata::DecodeDifferent::Encode(
+			$crate::metadata::FnEncode(
+				$mod::$module::<$runtime $(, $mod::$instance )?>::storage_metadata
+			)
+		))
+	};
+	(
+		$mod: ident,
+		$module: ident $( <$instance:ident> )?,
+		$runtime: ident,
+		with $_:ident
+		$(with $kws:ident)*
+	) => {
+		$crate::__runtime_modules_to_metadata_calls_storage! {
+			$mod, $module $( <$instance> )?, $runtime, $(with $kws)*
+		};
+	};
+	(
+		$mod: ident,
+		$module: ident $( <$instance:ident> )?,
+		$runtime: ident,
+	) => {
+		None
+	};
+}
+
+
+#[cfg(test)]
+// Do not complain about unused `dispatch` and `dispatch_aux`.
+#[allow(dead_code)]
+mod tests {
+	use super::*;
+	use palette_metadata::{
+		EventMetadata, StorageEntryModifier, StorageEntryType, FunctionMetadata, StorageEntryMetadata,
+		ModuleMetadata, RuntimeMetadataPrefixed, DefaultByte, ModuleConstantMetadata, DefaultByteGetter,
+		ErrorMetadata,
+	};
+	use codec::{Encode, Decode};
+	use crate::traits::Get;
+
+	mod system {
+		use super::*;
+
+		pub trait Trait {
+			const ASSOCIATED_CONST: u64 = 500;
+			type Origin: Into<Result<RawOrigin<Self::AccountId>, Self::Origin>>
+				+ From<RawOrigin<Self::AccountId>>;
+			type AccountId: From<u32> + Encode;
+			type BlockNumber: From<u32> + Encode;
+			type SomeValue: Get<u32>;
+		}
+
+		decl_module! {
+			pub struct Module<T: Trait> for enum Call where origin: T::Origin {
+				/// Hi, I am a comment.
+				const BlockNumber: T::BlockNumber = 100.into();
+				const GetType: T::AccountId = T::SomeValue::get().into();
+				const ASSOCIATED_CONST: u64 = T::ASSOCIATED_CONST.into();
+			}
+		}
+
+		decl_event!(
+			pub enum Event {
+				SystemEvent,
+			}
+		);
+
+		#[derive(Clone, PartialEq, Eq, Debug)]
+		pub enum RawOrigin<AccountId> {
+			Root,
+			Signed(AccountId),
+			None,
+		}
+
+		impl<AccountId> From<Option<AccountId>> for RawOrigin<AccountId> {
+			fn from(s: Option<AccountId>) -> RawOrigin<AccountId> {
+				match s {
+					Some(who) => RawOrigin::Signed(who),
+					None => RawOrigin::None,
+				}
+			}
+		}
+
+		pub type Origin<T> = RawOrigin<<T as Trait>::AccountId>;
+	}
+
+	mod event_module {
+		use crate::dispatch::DispatchResult;
+
+		pub trait Trait {
+			type Origin;
+			type Balance;
+			type BlockNumber;
+		}
+
+		decl_event!(
+			pub enum Event<T> where <T as Trait>::Balance
+			{
+				/// Hi, I am a comment.
+				TestEvent(Balance),
+			}
+		);
+
+		decl_module! {
+			pub struct Module<T: Trait> for enum Call where origin: T::Origin {
+				type Error = Error;
+
+				fn aux_0(_origin) -> DispatchResult<Error> { unreachable!() }
+			}
+		}
+
+		crate::decl_error! {
+			pub enum Error {
+				/// Some user input error
+				UserInputError,
+				/// Something bad happened
+				/// this could be due to many reasons
+				BadThingHappened,
+			}
+		}
+	}
+
+	mod event_module2 {
+		pub trait Trait {
+			type Origin;
+			type Balance;
+			type BlockNumber;
+		}
+
+		decl_event!(
+			pub enum Event<T> where <T as Trait>::Balance
+			{
+				TestEvent(Balance),
+			}
+		);
+
+		decl_module! {
+			pub struct Module<T: Trait> for enum Call where origin: T::Origin {}
+		}
+
+		crate::decl_storage! {
+			trait Store for Module<T: Trait> as TestStorage {
+				StorageMethod : Option<u32>;
+			}
+			add_extra_genesis {
+				build(|_| {});
+			}
+		}
+	}
+
+	type EventModule = event_module::Module<TestRuntime>;
+	type EventModule2 = event_module2::Module<TestRuntime>;
+
+	#[derive(Debug, Clone, PartialEq, Eq, Encode, Decode)]
+	pub struct TestRuntime;
+
+	impl_outer_event! {
+		pub enum TestEvent for TestRuntime {
+			event_module<T>,
+			event_module2<T>,
+		}
+	}
+
+	impl_outer_origin! {
+		pub enum Origin for TestRuntime {}
+	}
+
+	impl_outer_dispatch! {
+		pub enum Call for TestRuntime where origin: Origin {
+			event_module::EventModule,
+			event_module2::EventModule2,
+		}
+	}
+
+	impl event_module::Trait for TestRuntime {
+		type Origin = Origin;
+		type Balance = u32;
+		type BlockNumber = u32;
+	}
+
+	impl event_module2::Trait for TestRuntime {
+		type Origin = Origin;
+		type Balance = u32;
+		type BlockNumber = u32;
+	}
+
+	crate::parameter_types! {
+		pub const SystemValue: u32 = 600;
+	}
+
+	impl system::Trait for TestRuntime {
+		type Origin = Origin;
+		type AccountId = u32;
+		type BlockNumber = u32;
+		type SomeValue = SystemValue;
+	}
+
+	impl_runtime_metadata!(
+		for TestRuntime with modules
+			system::Module as System with Event,
+			event_module::Module as Module with Event Call,
+			event_module2::Module as Module2 with Event Storage Call,
+	);
+
+	struct ConstantBlockNumberByteGetter;
+	impl DefaultByte for ConstantBlockNumberByteGetter {
+		fn default_byte(&self) -> Vec<u8> {
+			100u32.encode()
+		}
+	}
+
+	struct ConstantGetTypeByteGetter;
+	impl DefaultByte for ConstantGetTypeByteGetter {
+		fn default_byte(&self) -> Vec<u8> {
+			SystemValue::get().encode()
+		}
+	}
+
+	struct ConstantAssociatedConstByteGetter;
+	impl DefaultByte for ConstantAssociatedConstByteGetter {
+		fn default_byte(&self) -> Vec<u8> {
+			<TestRuntime as system::Trait>::ASSOCIATED_CONST.encode()
+		}
+	}
+
+	const EXPECTED_METADATA: RuntimeMetadataLastVersion = RuntimeMetadataLastVersion {
+		modules: DecodeDifferent::Encode(&[
+			ModuleMetadata {
+				name: DecodeDifferent::Encode("System"),
+				storage: None,
+				calls: None,
+				event: Some(DecodeDifferent::Encode(
+					FnEncode(||&[
+						EventMetadata {
+							name: DecodeDifferent::Encode("SystemEvent"),
+							arguments: DecodeDifferent::Encode(&[]),
+							documentation: DecodeDifferent::Encode(&[])
+						}
+					])
+				)),
+				constants: DecodeDifferent::Encode(
+					FnEncode(|| &[
+						ModuleConstantMetadata {
+							name: DecodeDifferent::Encode("BlockNumber"),
+							ty: DecodeDifferent::Encode("T::BlockNumber"),
+							value: DecodeDifferent::Encode(
+								DefaultByteGetter(&ConstantBlockNumberByteGetter)
+							),
+							documentation: DecodeDifferent::Encode(&[" Hi, I am a comment."]),
+						},
+						ModuleConstantMetadata {
+							name: DecodeDifferent::Encode("GetType"),
+							ty: DecodeDifferent::Encode("T::AccountId"),
+							value: DecodeDifferent::Encode(
+								DefaultByteGetter(&ConstantGetTypeByteGetter)
+							),
+							documentation: DecodeDifferent::Encode(&[]),
+						},
+						ModuleConstantMetadata {
+							name: DecodeDifferent::Encode("ASSOCIATED_CONST"),
+							ty: DecodeDifferent::Encode("u64"),
+							value: DecodeDifferent::Encode(
+								DefaultByteGetter(&ConstantAssociatedConstByteGetter)
+							),
+							documentation: DecodeDifferent::Encode(&[]),
+						}
+					])
+				),
+				errors: DecodeDifferent::Encode(FnEncode(|| &[])),
+			},
+			ModuleMetadata {
+				name: DecodeDifferent::Encode("Module"),
+				storage: None,
+				calls: Some(
+					DecodeDifferent::Encode(FnEncode(|| &[
+						FunctionMetadata {
+							name: DecodeDifferent::Encode("aux_0"),
+							arguments: DecodeDifferent::Encode(&[]),
+							documentation: DecodeDifferent::Encode(&[]),
+						}
+					]))),
+				event: Some(DecodeDifferent::Encode(
+					FnEncode(||&[
+						EventMetadata {
+							name: DecodeDifferent::Encode("TestEvent"),
+							arguments: DecodeDifferent::Encode(&["Balance"]),
+							documentation: DecodeDifferent::Encode(&[" Hi, I am a comment."])
+						}
+					])
+				)),
+				constants: DecodeDifferent::Encode(FnEncode(|| &[])),
+				errors: DecodeDifferent::Encode(FnEncode(|| &[
+					ErrorMetadata {
+						name: DecodeDifferent::Encode("UserInputError"),
+						documentation: DecodeDifferent::Encode(&[" Some user input error"]),
+					},
+					ErrorMetadata {
+						name: DecodeDifferent::Encode("BadThingHappened"),
+						documentation: DecodeDifferent::Encode(&[
+							" Something bad happened",
+							" this could be due to many reasons",
+						]),
+					},
+				])),
+			},
+			ModuleMetadata {
+				name: DecodeDifferent::Encode("Module2"),
+				storage: Some(DecodeDifferent::Encode(
+					FnEncode(|| StorageMetadata {
+						prefix: DecodeDifferent::Encode("TestStorage"),
+						entries: DecodeDifferent::Encode(
+							&[
+								StorageEntryMetadata {
+									name: DecodeDifferent::Encode("StorageMethod"),
+									modifier: StorageEntryModifier::Optional,
+									ty: StorageEntryType::Plain(DecodeDifferent::Encode("u32")),
+									default: DecodeDifferent::Encode(
+										DefaultByteGetter(
+											&event_module2::__GetByteStructStorageMethod(
+												std::marker::PhantomData::<TestRuntime>
+											)
+										)
+									),
+									documentation: DecodeDifferent::Encode(&[]),
+								}
+							]
+						)
+					}),
+				)),
+				calls: Some(DecodeDifferent::Encode(FnEncode(|| &[]))),
+				event: Some(DecodeDifferent::Encode(
+					FnEncode(||&[
+						EventMetadata {
+							name: DecodeDifferent::Encode("TestEvent"),
+							arguments: DecodeDifferent::Encode(&["Balance"]),
+							documentation: DecodeDifferent::Encode(&[])
+						}
+					])
+				)),
+				constants: DecodeDifferent::Encode(FnEncode(|| &[])),
+				errors: DecodeDifferent::Encode(FnEncode(|| &[])),
+			},
+		])
+	};
+
+	#[test]
+	fn runtime_metadata() {
+		let metadata_encoded = TestRuntime::metadata().encode();
+		let metadata_decoded = RuntimeMetadataPrefixed::decode(&mut &metadata_encoded[..]);
+		let expected_metadata: RuntimeMetadataPrefixed = EXPECTED_METADATA.into();
+
+		pretty_assertions::assert_eq!(expected_metadata, metadata_decoded.unwrap());
+	}
+}

substrate/palette/support/src/origin.rs

@@ -0,0 +1,300 @@
+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Macros that define an Origin type. Every function call to your runtime has an origin which
+//! specifies where the extrinsic was generated from.
+
+/// Constructs an Origin type for a runtime. This is usually called automatically by the
+/// construct_runtime macro. See also __create_decl_macro.
+#[macro_export]
+macro_rules! impl_outer_origin {
+
+	// Macro transformations (to convert invocations with incomplete parameters to the canonical
+	// form)
+	(
+		$(#[$attr:meta])*
+		pub enum $name:ident for $runtime:ident {
+			$( $rest_without_system:tt )*
+		}
+	) => {
+		$crate::impl_outer_origin! {
+			$(#[$attr])*
+			pub enum $name for $runtime where system = system {
+				$( $rest_without_system )*
+			}
+		}
+	};
+
+	(
+		$(#[$attr:meta])*
+		pub enum $name:ident for $runtime:ident where system = $system:ident {
+			$( $rest_with_system:tt )*
+		}
+	) => {
+		$crate::impl_outer_origin!(
+			$( #[$attr] )*;
+			$name;
+			$runtime;
+			$system;
+			Modules { $( $rest_with_system )* };
+		);
+	};
+
+	// Generic + Instance
+	(
+		$(#[$attr:meta])*;
+		$name:ident;
+		$runtime:ident;
+		$system:ident;
+		Modules {
+			$module:ident $instance:ident <T>
+			$(, $( $rest_module:tt )* )?
+		};
+		$( $parsed:tt )*
+	) => {
+		$crate::impl_outer_origin!(
+			$( #[$attr] )*;
+			$name;
+			$runtime;
+			$system;
+			Modules { $( $( $rest_module )* )? };
+			$( $parsed )* $module <$runtime> { $instance },
+		);
+	};
+
+	// Instance
+	(
+		$(#[$attr:meta])*;
+		$name:ident;
+		$runtime:ident;
+		$system:ident;
+		Modules {
+			$module:ident $instance:ident
+			$(, $rest_module:tt )*
+		};
+		$( $parsed:tt )*
+	) => {
+		$crate::impl_outer_origin!(
+			$( #[$attr] )*;
+			$name;
+			$runtime;
+			$system;
+			Modules { $( $rest_module )* };
+			$( $parsed )* $module { $instance },
+		);
+	};
+
+	// Generic
+	(
+		$(#[$attr:meta])*;
+		$name:ident;
+		$runtime:ident;
+		$system:ident;
+		Modules {
+			$module:ident <T>
+			$(, $( $rest_module:tt )* )?
+		};
+		$( $parsed:tt )*
+	) => {
+		$crate::impl_outer_origin!(
+			$( #[$attr] )*;
+			$name;
+			$runtime;
+			$system;
+			Modules { $( $( $rest_module )* )? };
+			$( $parsed )* $module <$runtime>,
+		);
+	};
+
+	// No Generic and no Instance
+	(
+		$(#[$attr:meta])*;
+		$name:ident;
+		$runtime:ident;
+		$system:ident;
+		Modules {
+			$module:ident
+			$(, $( $rest_module:tt )* )?
+		};
+		$( $parsed:tt )*
+	) => {
+		$crate::impl_outer_origin!(
+			$( #[$attr] )*;
+			$name;
+			$runtime;
+			$system;
+			Modules { $( $( $rest_module )* )? };
+			$( $parsed )* $module,
+		);
+	};
+
+	// The main macro expansion that actually renders the Origin enum code.
+	(
+		$(#[$attr:meta])*;
+		$name:ident;
+		$runtime:ident;
+		$system:ident;
+		Modules { };
+		$( $module:ident $( < $generic:ident > )? $( { $generic_instance:ident } )? ,)*
+	) => {
+		$crate::paste::item! {
+			#[derive(Clone, PartialEq, Eq, $crate::RuntimeDebug)]
+			$(#[$attr])*
+			#[allow(non_camel_case_types)]
+			pub enum $name {
+				system($system::Origin<$runtime>),
+				$(
+					[< $module $( _ $generic_instance )? >]
+					($module::Origin < $( $generic, )? $( $module::$generic_instance )? > ),
+				)*
+				#[allow(dead_code)]
+				Void($crate::Void)
+			}
+		}
+
+		#[allow(dead_code)]
+		impl $name {
+			pub const NONE: Self = $name::system($system::RawOrigin::None);
+			pub const ROOT: Self = $name::system($system::RawOrigin::Root);
+			pub fn signed(by: <$runtime as $system::Trait>::AccountId) -> Self {
+				$name::system($system::RawOrigin::Signed(by))
+			}
+		}
+		impl From<$system::Origin<$runtime>> for $name {
+			fn from(x: $system::Origin<$runtime>) -> Self {
+				$name::system(x)
+			}
+		}
+		impl Into<$crate::rstd::result::Result<$system::Origin<$runtime>, $name>> for $name {
+			fn into(self) -> $crate::rstd::result::Result<$system::Origin<$runtime>, Self> {
+				if let $name::system(l) = self {
+					Ok(l)
+				} else {
+					Err(self)
+				}
+			}
+		}
+		impl From<Option<<$runtime as $system::Trait>::AccountId>> for $name {
+			fn from(x: Option<<$runtime as $system::Trait>::AccountId>) -> Self {
+				<$system::Origin<$runtime>>::from(x).into()
+			}
+		}
+		$(
+			$crate::paste::item! {
+				impl From<$module::Origin < $( $generic )? $(, $module::$generic_instance )? > > for $name {
+					fn from(x: $module::Origin < $( $generic )? $(, $module::$generic_instance )? >) -> Self {
+						$name::[< $module $( _ $generic_instance )? >](x)
+					}
+				}
+				impl Into<
+					$crate::rstd::result::Result<
+						$module::Origin < $( $generic )? $(, $module::$generic_instance )? >,
+						$name,
+					>>
+				for $name {
+					fn into(self) -> $crate::rstd::result::Result<
+						$module::Origin < $( $generic )? $(, $module::$generic_instance )? >,
+						Self,
+					> {
+						if let $name::[< $module $( _ $generic_instance )? >](l) = self {
+							Ok(l)
+						} else {
+							Err(self)
+						}
+					}
+				}
+			}
+		)*
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	mod system {
+		pub trait Trait {
+			type AccountId;
+		}
+
+		#[derive(Clone, PartialEq, Eq, Debug)]
+		pub enum RawOrigin<AccountId> {
+			Root,
+			Signed(AccountId),
+			None,
+		}
+
+		impl<AccountId> From<Option<AccountId>> for RawOrigin<AccountId> {
+			fn from(s: Option<AccountId>) -> RawOrigin<AccountId> {
+				match s {
+					Some(who) => RawOrigin::Signed(who),
+					None => RawOrigin::None,
+				}
+			}
+		}
+
+		pub type Origin<T> = RawOrigin<<T as Trait>::AccountId>;
+	}
+
+	mod origin_without_generic {
+		#[derive(Clone, PartialEq, Eq, Debug)]
+		pub struct Origin;
+	}
+
+	mod origin_with_generic {
+		#[derive(Clone, PartialEq, Eq, Debug)]
+		pub struct Origin<T> {
+			t: T
+		}
+	}
+
+	#[derive(Clone, PartialEq, Eq, Debug)]
+	pub struct TestRuntime;
+
+	impl system::Trait for TestRuntime {
+		type AccountId = u32;
+	}
+
+	impl_outer_origin!(
+		pub enum OriginWithoutSystem for TestRuntime {
+			origin_without_generic,
+			origin_with_generic<T>,
+		}
+	);
+
+	impl_outer_origin!(
+		pub enum OriginWithoutSystem2 for TestRuntime {
+			origin_with_generic<T>,
+			origin_without_generic
+		}
+	);
+
+	impl_outer_origin!(
+		pub enum OriginWithSystem for TestRuntime where system = system {
+			origin_without_generic,
+			origin_with_generic<T>
+		}
+	);
+
+	impl_outer_origin!(
+		pub enum OriginWithSystem2 for TestRuntime where system = system {
+			origin_with_generic<T>,
+			origin_without_generic,
+		}
+	);
+
+	impl_outer_origin!(
+		pub enum OriginEmpty for TestRuntime where system = system {}
+	);
+}

substrate/palette/support/src/runtime.rs

@@ -0,0 +1,948 @@
+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Macros to define a runtime. A runtime is basically all your logic running in Substrate,
+//! consisting of selected SRML modules and maybe some of your own modules.
+//! A lot of supporting logic is automatically generated for a runtime,
+//! mostly to combine data types and metadata of the included modules.
+
+/// Construct a runtime, with the given name and the given modules.
+///
+/// The parameters here are specific types for `Block`, `NodeBlock`, and `InherentData`
+/// and the modules that are used by the runtime.
+/// `Block` is the block type that is used in the runtime and `NodeBlock` is the block type
+/// that is used in the node. For instance they can differ in the extrinsics type.
+///
+/// # Example:
+///
+/// ```nocompile
+/// construct_runtime!(
+///     pub enum Runtime where
+///         Block = Block,
+///         NodeBlock = runtime::Block,
+///         UncheckedExtrinsic = UncheckedExtrinsic
+///     {
+///         System: system,
+///         Test: test::{default},
+///         Test2: test_with_long_module::{Module},
+///
+///         // Module with instances
+///         Test3_Instance1: test3::<Instance1>::{Module, Call, Storage, Event<T, I>, Config<T, I>, Origin<T, I>},
+///         Test3_DefaultInstance: test3::{Module, Call, Storage, Event<T>, Config<T>, Origin<T>},
+///     }
+/// )
+/// ```
+///
+/// The module `System: system` will expand to `System: system::{Module, Call, Storage, Event<T>, Config<T>}`.
+/// The identifier `System` is the name of the module and the lower case identifier `system` is the
+/// name of the Rust module/crate for this Substrate module.
+///
+/// The module `Test: test::{default}` will expand to
+/// `Test: test::{Module, Call, Storage, Event<T>, Config<T>}`.
+///
+/// The module `Test2: test_with_long_module::{Module}` will expand to
+/// `Test2: test_with_long_module::{Module}`.
+///
+/// We provide support for the following types in a module:
+///
+/// - `Module`
+/// - `Call`
+/// - `Storage`
+/// - `Event` or `Event<T>` (if the event is generic)
+/// - `Origin` or `Origin<T>` (if the origin is generic)
+/// - `Config` or `Config<T>` (if the config is generic)
+/// - `Inherent $( (CALL) )*` - If the module provides/can check inherents. The optional parameter
+///                             is for modules that use a `Call` from a different module as
+///                             inherent.
+/// - `ValidateUnsigned`      - If the module validates unsigned extrinsics.
+///
+/// # Note
+///
+/// The population of the genesis storage depends on the order of modules. So, if one of your
+/// modules depends on another module, the module that is depended upon needs to come before
+/// the module depending on it.
+#[macro_export]
+macro_rules! construct_runtime {
+
+	// Macro transformations (to convert invocations with incomplete parameters to the canonical
+	// form)
+
+	(
+		pub enum $runtime:ident
+			where
+				Block = $block:ident,
+				NodeBlock = $node_block:ty,
+				UncheckedExtrinsic = $uncheckedextrinsic:ident
+		{
+			$( $rest:tt )*
+		}
+	) => {
+		$crate::construct_runtime!(
+			{
+				$runtime;
+				$block;
+				$node_block;
+				$uncheckedextrinsic;
+			};
+			{};
+			$( $rest )*
+		);
+	};
+	// No modules given, expand to the default module set.
+	(
+		{ $( $preset:tt )* };
+		{ $( $expanded:tt )* };
+		$name:ident: $module:ident,
+		$( $rest:tt )*
+	) => {
+		$crate::construct_runtime!(
+			{ $( $preset )* };
+			{ $( $expanded )* };
+			$name: $module::{default},
+			$( $rest )*
+		);
+	};
+	// `default` identifier given, expand to default + given extra modules
+	(
+		{ $( $preset:tt )* };
+		{ $( $expanded:tt )* };
+		$name:ident: $module:ident::{
+			default
+			$(,
+				$modules:ident
+					$( <$modules_generic:ident> )*
+					$( ( $( $modules_args:ident ),* ) )*
+			)*
+		},
+		$( $rest:tt )*
+	) => {
+		$crate::construct_runtime!(
+			{ $( $preset )* };
+			{
+				$( $expanded )*
+				$name: $module::{
+					Module, Call, Storage, Event<T>, Config<T>
+					$(,
+						$modules $( <$modules_generic> )*
+						$( ( $( $modules_args ),* ) )*
+					)*
+				},
+			};
+			$( $rest )*
+		);
+	};
+	// Take all modules as given by the user.
+	(
+		{ $( $preset:tt )* };
+		{ $( $expanded:tt )* };
+		$name:ident: $module:ident :: $( < $module_instance:ident >:: )? {
+			$(
+				$modules:ident
+					$( <$modules_generic:ident> )*
+					$( ( $( $modules_args:ident ),* ) )*
+			),*
+		},
+		$( $rest:tt )*
+	) => {
+		$crate::construct_runtime!(
+			{ $( $preset )* };
+			{
+				$( $expanded )*
+				$name: $module:: $( < $module_instance >:: )? {
+					$(
+						$modules $( <$modules_generic> )*
+						$( ( $( $modules_args ),* ) )*
+					),*
+				},
+			};
+			$( $rest )*
+		);
+	};
+	// The main macro expansion that actually renders the Runtime code.
+	(
+		{
+			$runtime:ident;
+			$block:ident;
+			$node_block:ty;
+			$uncheckedextrinsic:ident;
+		};
+		{
+			$(
+				$name:ident: $module:ident :: $( < $module_instance:ident >:: )? {
+					$(
+						$modules:ident
+							$( <$modules_generic:ident> )*
+							$( ( $( $modules_args:ident ),* ) )*
+					),*
+				},
+			)*
+		};
+	) => {
+		#[derive(Clone, Copy, PartialEq, Eq, $crate::RuntimeDebug)]
+		pub struct $runtime;
+		impl $crate::sr_primitives::traits::GetNodeBlockType for $runtime {
+			type NodeBlock = $node_block;
+		}
+		impl $crate::sr_primitives::traits::GetRuntimeBlockType for $runtime {
+			type RuntimeBlock = $block;
+		}
+		$crate::__decl_outer_event!(
+			$runtime;
+			$(
+				$name: $module:: $( < $module_instance >:: )? {
+					$( $modules $( <$modules_generic> )* ),*
+				}
+			),*
+		);
+		$crate::__decl_outer_origin!(
+			$runtime;
+			$(
+				$name: $module:: $( < $module_instance >:: )? {
+					$( $modules $( <$modules_generic> )* ),*
+				}
+			),*
+		);
+		$crate::__decl_all_modules!(
+			$runtime;
+			;
+			{};
+			{};
+			$(
+				$name: $module:: $( < $module_instance >:: )? { $( $modules ),* },
+			)*
+		);
+		$crate::__decl_outer_dispatch!(
+			$runtime;
+			;
+			$(
+				$name: $module::{ $( $modules ),* }
+			),*;
+		);
+		$crate::__decl_runtime_metadata!(
+			$runtime;
+			{};
+			$(
+				$name: $module:: $( < $module_instance >:: )? { $( $modules )* }
+			)*
+		);
+		$crate::__decl_outer_config!(
+			$runtime;
+			{};
+			$(
+				$name: $module:: $( < $module_instance >:: )? {
+					$( $modules $( <$modules_generic> )* ),*
+				},
+			)*
+		);
+		$crate::__decl_outer_inherent!(
+			$runtime;
+			$block;
+			$uncheckedextrinsic;
+			;
+			$(
+				$name: $module::{ $( $modules $( ( $( $modules_args )* ) )* ),* }
+			),*;
+		);
+		$crate::__impl_outer_validate_unsigned!(
+			$runtime;
+			{};
+			$(
+				$name: $module::{ $( $modules $( ( $( $modules_args )* ) )* )* }
+			)*
+		);
+	}
+}
+
+/// A macro that generates a "__decl" private macro that transforms parts of the runtime definition
+/// to feed them into a public "impl" macro which accepts the format
+/// "pub enum $name for $runtime where system = $system".
+///
+/// Used to define Event and Origin associated types.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __create_decl_macro {
+	(
+		// Parameter $d is a hack for the following issue:
+		// https://github.com/rust-lang/rust/issues/35853
+		$macro_name:ident, $macro_outer_name:ident, $macro_enum_name:ident, $d:tt
+	) => {
+		#[macro_export]
+		#[doc(hidden)]
+		macro_rules! $macro_name {
+			(
+				$runtime:ident;
+				$d( $name:ident : $module:ident:: $d( < $module_instance:ident >:: )? {
+					$d( $modules:ident $d( <$modules_generic:ident> ),* ),*
+				}),*
+			) => {
+				$d crate::$macro_name!(@inner
+					$runtime;
+					;
+					{};
+					$d(
+						$name: $module:: $d( < $module_instance >:: )? {
+							$d( $modules $d( <$modules_generic> )* ),*
+						},
+					)*
+				);
+			};
+			// Parse system module
+			(@inner
+				$runtime:ident;
+				; // there can not be multiple `System`s
+				{ $d( $parsed:tt )* };
+				System: $module:ident::{
+					$d( $modules:ident $d( <$modules_generic:ident> )* ),*
+				},
+				$d( $rest:tt )*
+			) => {
+				$d crate::$macro_name!(@inner
+					$runtime;
+					$module;
+					{ $d( $parsed )* };
+					$d( $rest )*
+				);
+			};
+			// Parse instantiable module with generic
+			(@inner
+				$runtime:ident;
+				$d( $system:ident )?;
+				{ $d( $parsed:tt )* };
+				$name:ident : $module:ident:: < $module_instance:ident >:: {
+					$macro_enum_name <$event_generic:ident> $d(, $ingore:ident $d( <$ignor:ident> )* )*
+				},
+				$d( $rest:tt )*
+			) => {
+				$d crate::$macro_name!(@inner
+					$runtime;
+					$d( $system )?;
+					{
+						$d( $parsed )*
+						$module $module_instance <$event_generic>,
+					};
+					$d( $rest )*
+				);
+			};
+			// Parse instantiable module with no generic
+			(@inner
+				$runtime:ident;
+				$d( $system:ident )?;
+				{ $d( $parsed:tt )* };
+				$name:ident : $module:ident:: < $module_instance:ident >:: {
+					$macro_enum_name $d(, $ingore:ident $d( <$ignor:ident> )* )*
+				},
+				$d( $rest:tt )*
+			) => {
+				compile_error!(concat!(
+					"Instantiable module with not generic ", stringify!($macro_enum_name),
+					" cannot be constructed: module `", stringify!($name), "` must have generic ",
+					stringify!($macro_enum_name), "."
+				));
+			};
+			// Parse instantiable module with no generic
+			(@inner
+				$runtime:ident;
+				$d( $system:ident )?;
+				{ $d( $parsed:tt )* };
+				$name:ident : $module:ident:: {
+					$macro_enum_name $d( <$event_generic:ident> )* $d(, $ignore:ident $d( <$ignor:ident> )* )*
+				},
+				$d( $rest:tt )*
+			) => {
+				$d crate::$macro_name!(@inner
+					$runtime;
+					$d( $system )?;
+					{
+						$d( $parsed )*
+						$module $d( <$event_generic> )*,
+					};
+					$d( $rest )*
+				);
+			};
+			// Ignore keyword
+			(@inner
+				$runtime:ident;
+				$d( $system:ident )?;
+				{ $d( $parsed:tt )* };
+				$name:ident : $module:ident:: $d( < $module_instance:ident >:: )? {
+					$ingore:ident $d( <$ignor:ident> )* $d(, $modules:ident $d( <$modules_generic:ident> )* )*
+				},
+				$d( $rest:tt )*
+			) => {
+				$d crate::$macro_name!(@inner
+					$runtime;
+					$d( $system )?;
+					{ $d( $parsed )* };
+					$name: $module:: $d( < $module_instance >:: )? { $d( $modules $d( <$modules_generic> )* ),* },
+					$d( $rest )*
+				);
+			};
+			// Ignore module
+			(@inner
+				$runtime:ident;
+				$d( $system:ident )?;
+				{ $d( $parsed:tt )* };
+				$name:ident: $module:ident:: $d( < $module_instance:ident >:: )? {},
+				$d( $rest:tt )*
+			) => {
+				$d crate::$macro_name!(@inner
+					$runtime;
+					$d( $system )?;
+					{ $d( $parsed )* };
+					$d( $rest )*
+				);
+			};
+			// Expand
+			(@inner
+				$runtime:ident;
+				$system:ident;
+				{ $d( $parsed_modules:ident $d( $instance:ident )? $d( <$parsed_generic:ident> )? ,)* };
+			) => {
+				$d crate::$macro_outer_name! {
+					pub enum $macro_enum_name for $runtime where system = $system {
+						$d(
+							$parsed_modules $d( $instance )? $d( <$parsed_generic> )?,
+						)*
+					}
+				}
+			}
+		}
+	}
+}
+
+__create_decl_macro!(__decl_outer_event, impl_outer_event, Event, $);
+__create_decl_macro!(__decl_outer_origin, impl_outer_origin, Origin, $);
+
+/// A macro that defines all modules as an associated types of the Runtime type.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __decl_all_modules {
+	(
+		$runtime:ident;
+		;
+		{ $( $parsed:tt )* };
+		{ $( $parsed_nested:tt )* };
+		System: $module:ident::{ Module $(, $modules:ident )* },
+		$( $rest:tt )*
+	) => {
+		$crate::__decl_all_modules!(
+			$runtime;
+			$module;
+			{ $( $parsed )* };
+			{ $( $parsed_nested )* };
+			$( $rest )*
+		);
+	};
+	(
+		$runtime:ident;
+		$( $system:ident )?;
+		{ $( $parsed:tt )* };
+		{};
+		$name:ident: $module:ident:: $( < $module_instance:ident >:: )? { Module $(, $modules:ident )* },
+		$( $rest:tt )*
+	) => {
+		$crate::__decl_all_modules!(
+			$runtime;
+			$( $system )?;
+			{
+				$( $parsed )*
+				$module::$name $(<$module_instance>)?,
+			};
+			{ $name };
+			$( $rest )*
+		);
+	};
+	(
+		$runtime:ident;
+		$( $system:ident )?;
+		{ $( $parsed:tt )* };
+		{ $( $parsed_nested:tt )* };
+		$name:ident: $module:ident:: $( < $module_instance:ident >:: )? { Module $(, $modules:ident )* },
+		$( $rest:tt )*
+	) => {
+		$crate::__decl_all_modules!(
+			$runtime;
+			$( $system )?;
+			{
+				$( $parsed )*
+				$module::$name $(<$module_instance>)?,
+			};
+			{ ( $( $parsed_nested )*, $name, ) };
+			$( $rest )*
+		);
+	};
+	(
+		$runtime:ident;
+		$( $system:ident )?;
+		{ $( $parsed:tt )* };
+		{ $( $parsed_nested:tt )* };
+		$name:ident: $module:ident:: $( < $module_instance:ident >:: )? { $ignore:ident $(, $modules:ident )* },
+		$( $rest:tt )*
+	) => {
+		$crate::__decl_all_modules!(
+			$runtime;
+			$( $system )?;
+			{ $( $parsed )* };
+			{ $( $parsed_nested )* };
+			$name: $module::{ $( $modules ),* },
+			$( $rest )*
+		);
+	};
+	(
+		$runtime:ident;
+		$( $system:ident )?;
+		{ $( $parsed:tt )* };
+		$name:ident: $module:ident:: $( < $module_instance:ident >:: )? {},
+		$( $rest:tt )*
+	) => {
+		$crate::__decl_all_modules!(
+			$runtime;
+			$( $system )?;
+			{ $( $parsed )* };
+			{ $( $parsed_nested )* };
+			$( $rest )*
+		);
+	};
+	(
+		$runtime:ident;
+		$system:ident;
+		{ $( $parsed_module:ident :: $parsed_name:ident $(<$instance:ident>)? ,)*};
+		{ $( $parsed_nested:tt )* };
+	) => {
+		pub type System = system::Module<$runtime>;
+		$(
+			pub type $parsed_name = $parsed_module::Module<$runtime $(, $parsed_module::$instance )?>;
+		)*
+		type AllModules = ( $( $parsed_nested )* );
+	}
+}
+
+/// A macro that defines the Call enum to represent calls to functions in the modules included
+/// in the runtime (by wrapping the values of all FooModule::Call enums).
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __decl_outer_dispatch {
+	(
+		$runtime:ident;
+		$( $parsed_modules:ident :: $parsed_name:ident ),*;
+		$name:ident: $module:ident::{
+			Call $(, $modules:ident $( <$modules_generic:ident> )* )*
+		}
+		$(, $rest_name:ident : $rest_module:ident::{
+			$( $rest_modules:ident $( <$rest_modules_generic:ident> )* ),*
+		})*;
+	) => {
+		$crate::__decl_outer_dispatch!(
+			$runtime;
+			$( $parsed_modules :: $parsed_name, )* $module::$name;
+			$(
+				$rest_name: $rest_module::{
+					$( $rest_modules $( <$rest_modules_generic> )* ),*
+				}
+			),*;
+		);
+	};
+	(
+		$runtime:ident;
+		$( $parsed_modules:ident :: $parsed_name:ident ),*;
+		$name:ident: $module:ident::{
+			$ignore:ident $( <$ignor:ident> )* $(, $modules:ident $( <$modules_generic:ident> )* )*
+		}
+		$(, $rest_name:ident : $rest_module:ident::{
+			$( $rest_modules:ident $( <$rest_modules_generic:ident> )* ),*
+		})*;
+	) => {
+		$crate::__decl_outer_dispatch!(
+			$runtime;
+			$( $parsed_modules :: $parsed_name ),*;
+			$name: $module::{ $( $modules $( <$modules_generic> )* ),* }
+			$(
+				, $rest_name: $rest_module::{
+					$( $rest_modules $( <$rest_modules_generic> )* ),*
+				}
+			)*;
+		);
+	};
+	(
+		$runtime:ident;
+		$( $parsed_modules:ident :: $parsed_name:ident ),*;
+		$name:ident: $module:ident::{}
+		$(, $rest_name:ident : $rest_module:ident::{
+			$( $rest_modules:ident $( <$rest_modules_generic:ident> )* ),*
+		})*;
+	) => {
+		$crate::__decl_outer_dispatch!(
+			$runtime;
+			$( $parsed_modules :: $parsed_name ),*;
+			$(
+				$rest_name: $rest_module::{
+					$( $rest_modules $( <$rest_modules_generic> )* ),*
+				}
+			),*;
+		);
+	};
+	(
+		$runtime:ident;
+		$( $parsed_modules:ident :: $parsed_name:ident ),*;
+		;
+	) => {
+		$crate::impl_outer_dispatch!(
+			pub enum Call for $runtime where origin: Origin {
+				$( $parsed_modules::$parsed_name, )*
+			}
+		);
+	};
+}
+
+/// A private macro that generates metadata() method for the runtime. See impl_runtime_metadata macro.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __decl_runtime_metadata {
+	// leading is Module : parse
+	(
+		$runtime:ident;
+		{ $( $parsed:tt )* };
+		$( { leading_module: $( $leading_module:ident )* } )?
+		$name:ident: $module:ident:: $( < $module_instance:ident >:: )? {
+			Module $( $modules:ident )*
+		}
+		$( $rest:tt )*
+	) => {
+		$crate::__decl_runtime_metadata!(
+			$runtime;
+			{
+				$( $parsed )*
+				$module $( < $module_instance > )? as $name {
+					$( $( $leading_module )* )? $( $modules )*
+				}
+			};
+			$( $rest )*
+		);
+	};
+	// leading isn't Module : put it in leadings
+	(
+		$runtime:ident;
+		{ $( $parsed:tt )* };
+		$( { leading_module: $( $leading_module:ident )* } )?
+		$name:ident: $module:ident:: $( < $module_instance:ident >:: )? {
+			$other_module:ident $( $modules:ident )*
+		}
+		$( $rest:tt )*
+	) => {
+		$crate::__decl_runtime_metadata!(
+			$runtime;
+			{ $( $parsed )* };
+			{ leading_module: $( $( $leading_module )* )? $other_module }
+			$name: $module:: $( < $module_instance >:: )? {
+				$( $modules )*
+			}
+			$( $rest )*
+		);
+	};
+	// does not contain Module : skip
+	(
+		$runtime:ident;
+		{ $( $parsed:tt )* };
+		$( { leading_module: $( $leading_module:ident )* } )?
+		$name:ident: $module:ident:: $( < $module_instance:ident >:: )? {}
+		$( $rest:tt )*
+	) => {
+		$crate::__decl_runtime_metadata!(
+			$runtime;
+			{ $( $parsed )* };
+			$( $rest )*
+		);
+	};
+	// end of decl
+	(
+		$runtime:ident;
+		{
+			$(
+				$parsed_modules:ident $( < $module_instance:ident > )? as $parsed_name:ident {
+					$( $withs:ident )*
+				}
+			)*
+		};
+	) => {
+		$crate::impl_runtime_metadata!(
+			for $runtime with modules
+				$( $parsed_modules::Module $( < $module_instance > )? as $parsed_name
+					with $( $withs )* , )*
+		);
+	}
+}
+
+/// A private macro that generates GenesisConfig for the runtime. See `impl_outer_config!` macro.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __decl_outer_config {
+	(
+		$runtime:ident;
+		{ $( $parsed:tt )* };
+		$name:ident: $module:ident:: $( < $module_instance:ident >:: )? {
+			Config $( <$config_generic:ident> )?
+			$(, $modules:ident $( <$modules_generic:ident> )* )*
+		},
+		$( $rest:tt )*
+	) => {
+		$crate::__decl_outer_config!(
+			$runtime;
+			{
+				$( $parsed )*
+				$module::$name $( $module_instance )? $( <$config_generic> )?,
+			};
+			$( $rest )*
+		);
+	};
+	(
+		$runtime:ident;
+		{ $( $parsed:tt )* };
+		$name:ident: $module:ident:: $( < $module_instance:ident >:: )? {
+			$ingore:ident $( <$ignore_gen:ident> )*
+			$(, $modules:ident $( <$modules_generic:ident> )* )*
+		},
+		$( $rest:tt )*
+	) => {
+		$crate::__decl_outer_config!(
+			$runtime;
+			{ $( $parsed )* };
+			$name: $module:: $( < $module_instance >:: )? { $( $modules $( <$modules_generic> )* ),* },
+			$( $rest )*
+		);
+	};
+	(
+		$runtime:ident;
+		{ $( $parsed:tt )* };
+		$name:ident: $module:ident:: $( < $module_instance:ident >:: )? {},
+		$( $rest:tt )*
+	) => {
+		$crate::__decl_outer_config!(
+			$runtime;
+			{ $( $parsed )* };
+			$( $rest )*
+		);
+	};
+	(
+		$runtime:ident;
+		{
+			$(
+				$parsed_modules:ident :: $parsed_name:ident $( $parsed_instance:ident )?
+				$(
+					<$parsed_generic:ident>
+				)*
+			,)*
+		};
+	) => {
+		$crate::paste::item! {
+			$crate::sr_primitives::impl_outer_config!(
+				pub struct GenesisConfig for $runtime {
+					$(
+						[< $parsed_name Config >] =>
+							$parsed_modules $( $parsed_instance )? $( <$parsed_generic> )*,
+					)*
+				}
+			);
+		}
+	};
+}
+
+/// A private macro that generates check_inherents() implementation for the runtime.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __decl_outer_inherent {
+	(
+		$runtime:ident;
+		$block:ident;
+		$uncheckedextrinsic:ident;
+		$( $parsed_name:ident :: $parsed_call:ident ),*;
+		$name:ident: $module:ident::{
+			Inherent $(, $modules:ident $( ( $( $modules_call:ident )* ) )* )*
+		}
+		$(, $rest_name:ident : $rest_module:ident::{
+			$( $rest_modules:ident $( ( $( $rest_call:ident )* ) )* ),*
+		})*;
+	) => {
+		$crate::__decl_outer_inherent!(
+			$runtime;
+			$block;
+			$uncheckedextrinsic;
+			$( $parsed_name :: $parsed_call, )* $name::$name;
+			$(
+				$rest_name: $rest_module::{
+					$( $rest_modules $( ( $( $rest_call )* ) )* ),*
+				}
+			),*;
+		);
+	};
+	(
+		$runtime:ident;
+		$block:ident;
+		$uncheckedextrinsic:ident;
+		$( $parsed_name:ident :: $parsed_call:ident ),*;
+		$name:ident: $module:ident::{
+			Inherent ( $call:ident ) $(, $modules:ident $( ( $( $modules_call:ident )* ) )* )*
+		}
+		$(, $rest_name:ident : $rest_module:ident::{
+			$( $rest_modules:ident $( ( $( $rest_call:ident )* ) )* ),*
+		})*;
+	) => {
+		$crate::__decl_outer_inherent!(
+			$runtime;
+			$block;
+			$uncheckedextrinsic;
+			$( $parsed_name :: $parsed_call, )* $name::$call;
+			$(
+				$rest_name: $rest_module::{
+					$( $rest_modules $( ( $( $rest_call )* ) )* ),*
+				}
+			),*;
+		);
+	};
+	(
+		$runtime:ident;
+		$block:ident;
+		$uncheckedextrinsic:ident;
+		$( $parsed_name:ident :: $parsed_call:ident ),*;
+		$name:ident: $module:ident::{
+			$ignore:ident $( ( $( $ignor:ident )* ) )*
+				$(, $modules:ident $( ( $( $modules_call:ident )* ) )* )*
+		}
+		$(, $rest_name:ident : $rest_module:ident::{
+			$( $rest_modules:ident $( ( $( $rest_call:ident )* ) )* ),*
+		})*;
+	) => {
+		$crate::__decl_outer_inherent!(
+			$runtime;
+			$block;
+			$uncheckedextrinsic;
+			$( $parsed_name :: $parsed_call ),*;
+			$name: $module::{ $( $modules $( ( $( $modules_call )* ) )* ),* }
+			$(
+				, $rest_name: $rest_module::{
+					$( $rest_modules $( ( $( $rest_call )* ) )* ),*
+				}
+			)*;
+		);
+	};
+	(
+		$runtime:ident;
+		$block:ident;
+		$uncheckedextrinsic:ident;
+		$( $parsed_name:ident :: $parsed_call:ident ),*;
+		$name:ident: $module:ident::{}
+		$(, $rest_name:ident : $rest_module:ident::{
+			$( $rest_modules:ident $( ( $( $rest_call:ident )* ) )* ),*
+		})*;
+	) => {
+		$crate::__decl_outer_inherent!(
+			$runtime;
+			$block;
+			$uncheckedextrinsic;
+			$( $parsed_name :: $parsed_call ),*;
+			$(
+				$rest_name: $rest_module::{
+					$( $rest_modules $( ( $( $rest_call )* ) )* ),*
+				}
+			),*;
+		);
+	};
+	(
+		$runtime:ident;
+		$block:ident;
+		$uncheckedextrinsic:ident;
+		$( $parsed_name:ident :: $parsed_call:ident ),*;
+		;
+	) => {
+		$crate::impl_outer_inherent!(
+			impl Inherents where Block = $block, UncheckedExtrinsic = $uncheckedextrinsic {
+				$( $parsed_name : $parsed_call, )*
+			}
+		);
+	};
+}
+
+#[macro_export]
+#[doc(hidden)]
+// Those imports are used by event, config, origin and log macros to get access to its inner type
+macro_rules! __decl_instance_import {
+	( $( $module:ident <$instance:ident> )* ) => {
+		$crate::paste::item! {
+			$(use $module as [< $module _ $instance >];)*
+		}
+	};
+}
+
+/// A private macro that calls impl_outer_validate_unsigned for Call.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! __impl_outer_validate_unsigned {
+	(
+		$runtime:ident;
+		{ $( $parsed:tt )* };
+		$name:ident: $module:ident:: $(<$module_instance:ident>::)? {
+			ValidateUnsigned $( $modules:ident $( ( $( $modules_args:ident )* ) )* )*
+		}
+		$( $rest:tt )*
+	) => {
+		$crate::__impl_outer_validate_unsigned!(
+			$runtime;
+			{ $( $parsed )* $name };
+			$( $rest )*
+		);
+	};
+	(
+		$runtime:ident;
+		{ $( $parsed:tt )* };
+		$name:ident: $module:ident:: $(<$module_instance:ident>::)? {
+			$ignore:ident $( ( $( $args_ignore:ident )* ) )*
+			$( $modules:ident $( ( $( $modules_args:ident )* ) )* )*
+		}
+		$( $rest:tt )*
+	) => {
+		$crate::__impl_outer_validate_unsigned!(
+			$runtime;
+			{ $( $parsed )* };
+			$name: $module:: $(<$module_instance>::)? {
+				$( $modules $( ( $( $modules_args )* ) )* )*
+			}
+			$( $rest )*
+		);
+	};
+	(
+		$runtime:ident;
+		{ $( $parsed:tt )* };
+		$name:ident: $module:ident:: $(<$module_instance:ident>::)? {}
+		$( $rest:tt )*
+	) => {
+		$crate::__impl_outer_validate_unsigned!(
+			$runtime;
+			{ $( $parsed )* };
+			$( $rest )*
+		);
+	};
+	(
+		$runtime:ident;
+		{ $(
+			$parsed_modules:ident
+		)* };
+	) => {
+		$crate::impl_outer_validate_unsigned!(
+			impl ValidateUnsigned for $runtime {
+				$( $parsed_modules )*
+			}
+		);
+	};
+}

substrate/palette/support/src/storage/child.rs

@@ -0,0 +1,115 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Operation on runtime child storages.
+//!
+//! This module is a currently only a variant of unhashed with additional `storage_key`.
+//! Note that `storage_key` must be unique and strong (strong in the sense of being long enough to
+//! avoid collision from a resistant hash function (which unique implies)).
+// NOTE: could replace unhashed by having only one kind of storage (root being null storage key (storage_key can become Option<&[u8]>).
+
+use crate::rstd::prelude::*;
+use codec::{Codec, Encode, Decode};
+
+/// Return the value of the item in storage under `key`, or `None` if there is no explicit entry.
+pub fn get<T: Decode + Sized>(storage_key: &[u8], key: &[u8]) -> Option<T> {
+	runtime_io::storage::child_get(storage_key, key).map(|v| {
+		Decode::decode(&mut &v[..]).expect("storage is not null, therefore must be a valid type")
+	})
+}
+
+/// Return the value of the item in storage under `key`, or the type's default if there is no
+/// explicit entry.
+pub fn get_or_default<T: Decode + Sized + Default>(storage_key: &[u8], key: &[u8]) -> T {
+	get(storage_key, key).unwrap_or_else(Default::default)
+}
+
+/// Return the value of the item in storage under `key`, or `default_value` if there is no
+/// explicit entry.
+pub fn get_or<T: Decode + Sized>(storage_key: &[u8], key: &[u8], default_value: T) -> T {
+	get(storage_key, key).unwrap_or(default_value)
+}
+
+/// Return the value of the item in storage under `key`, or `default_value()` if there is no
+/// explicit entry.
+pub fn get_or_else<T: Decode + Sized, F: FnOnce() -> T>(
+	storage_key: &[u8],
+	key: &[u8],
+	default_value: F,
+) -> T {
+	get(storage_key, key).unwrap_or_else(default_value)
+}
+
+/// Put `value` in storage under `key`.
+pub fn put<T: Encode>(storage_key: &[u8], key: &[u8], value: &T) {
+	value.using_encoded(|slice| runtime_io::storage::child_set(storage_key, key, slice));
+}
+
+/// Remove `key` from storage, returning its value if it had an explicit entry or `None` otherwise.
+pub fn take<T: Decode + Sized>(storage_key: &[u8], key: &[u8]) -> Option<T> {
+	let r = get(storage_key, key);
+	if r.is_some() {
+		kill(storage_key, key);
+	}
+	r
+}
+
+/// Remove `key` from storage, returning its value, or, if there was no explicit entry in storage,
+/// the default for its type.
+pub fn take_or_default<T: Codec + Sized + Default>(storage_key: &[u8], key: &[u8]) -> T {
+	take(storage_key, key).unwrap_or_else(Default::default)
+}
+
+/// Return the value of the item in storage under `key`, or `default_value` if there is no
+/// explicit entry. Ensure there is no explicit entry on return.
+pub fn take_or<T: Codec + Sized>(storage_key: &[u8],key: &[u8], default_value: T) -> T {
+	take(storage_key, key).unwrap_or(default_value)
+}
+
+/// Return the value of the item in storage under `key`, or `default_value()` if there is no
+/// explicit entry. Ensure there is no explicit entry on return.
+pub fn take_or_else<T: Codec + Sized, F: FnOnce() -> T>(
+	storage_key: &[u8],
+	key: &[u8],
+	default_value: F,
+) -> T {
+	take(storage_key, key).unwrap_or_else(default_value)
+}
+
+/// Check to see if `key` has an explicit entry in storage.
+pub fn exists(storage_key: &[u8], key: &[u8]) -> bool {
+	runtime_io::storage::child_read(storage_key, key, &mut [0;0][..], 0).is_some()
+}
+
+/// Remove all `storage_key` key/values
+pub fn kill_storage(storage_key: &[u8]) {
+	runtime_io::storage::child_storage_kill(storage_key)
+}
+
+/// Ensure `key` has no explicit entry in storage.
+pub fn kill(storage_key: &[u8], key: &[u8]) {
+	runtime_io::storage::child_clear(storage_key, key);
+}
+
+/// Get a Vec of bytes from storage.
+pub fn get_raw(storage_key: &[u8], key: &[u8]) -> Option<Vec<u8>> {
+	runtime_io::storage::child_get(storage_key, key)
+}
+
+/// Put a raw byte slice into storage.
+pub fn put_raw(storage_key: &[u8], key: &[u8], value: &[u8]) {
+	runtime_io::storage::child_set(storage_key, key, value)
+}

substrate/palette/support/src/storage/generator/double_map.rs

@@ -0,0 +1,215 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+use rstd::prelude::*;
+use rstd::borrow::Borrow;
+use codec::{Ref, FullCodec, FullEncode, Encode, EncodeLike, EncodeAppend};
+use crate::{storage::{self, unhashed}, hash::StorageHasher};
+
+/// Generator for `StorageDoubleMap` used by `decl_storage`.
+///
+/// # Mapping of keys to a storage path
+///
+/// The storage key (i.e. the key under which the `Value` will be stored) is created from two parts.
+/// The first part is a hash of a concatenation of the `key1_prefix` and `Key1`. And the second part
+/// is a hash of a `Key2`.
+///
+/// Thus value for (key1, key2) is stored at:
+/// ```nocompile
+/// Hasher1(key1_prefix ++ key1) ++ Hasher2(key2)
+/// ```
+///
+/// # Warning
+///
+/// If the key1s are not trusted (e.g. can be set by a user), a cryptographic `hasher` such as
+/// `blake2_256` must be used for Hasher1. Otherwise, other values in storage can be compromised.
+/// If the key2s are not trusted (e.g. can be set by a user), a cryptographic `hasher` such as
+/// `blake2_256` must be used for Hasher2. Otherwise, other items in storage with the same first
+/// key can be compromised.
+pub trait StorageDoubleMap<K1: FullEncode, K2: FullEncode, V: FullCodec> {
+	/// The type that get/take returns.
+	type Query;
+
+	/// Hasher for the first key.
+	type Hasher1: StorageHasher;
+
+	/// Hasher for the second key.
+	type Hasher2: StorageHasher;
+
+	/// Get the prefix for first key.
+	fn key1_prefix() -> &'static [u8];
+
+	/// Convert an optional value retrieved from storage to the type queried.
+	fn from_optional_value_to_query(v: Option<V>) -> Self::Query;
+
+	/// Convert a query to an optional value into storage.
+	fn from_query_to_optional_value(v: Self::Query) -> Option<V>;
+
+	/// Generate the first part of the key used in top storage.
+	fn storage_double_map_final_key1<KArg1>(k1: KArg1) -> <Self::Hasher1 as StorageHasher>::Output
+	where
+		KArg1: EncodeLike<K1>,
+	{
+		let mut final_key1 = Self::key1_prefix().to_vec();
+		k1.encode_to(&mut final_key1);
+		Self::Hasher1::hash(&final_key1)
+	}
+
+	/// Generate the full key used in top storage.
+	fn storage_double_map_final_key<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Vec<u8>
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>,
+	{
+		let mut final_key = Self::storage_double_map_final_key1(k1).as_ref().to_vec();
+		final_key.extend_from_slice(k2.using_encoded(Self::Hasher2::hash).as_ref());
+		final_key
+	}
+}
+
+impl<K1, K2, V, G> storage::StorageDoubleMap<K1, K2, V> for G
+where
+	K1: FullEncode,
+	K2: FullEncode,
+	V: FullCodec,
+	G: StorageDoubleMap<K1, K2, V>,
+{
+	type Query = G::Query;
+
+	fn hashed_key_for<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Vec<u8>
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>,
+	{
+		Self::storage_double_map_final_key(k1, k2)
+	}
+
+	fn exists<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> bool
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>,
+	{
+		unhashed::exists(&Self::storage_double_map_final_key(k1, k2))
+	}
+
+	fn get<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Self::Query
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>,
+	{
+		G::from_optional_value_to_query(unhashed::get(&Self::storage_double_map_final_key(k1, k2)))
+	}
+
+	fn take<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Self::Query
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>,
+	{
+		let final_key = Self::storage_double_map_final_key(k1, k2);
+
+		let value = unhashed::take(&final_key);
+		G::from_optional_value_to_query(value)
+	}
+
+	fn insert<KArg1, KArg2, VArg>(k1: KArg1, k2: KArg2, val: VArg)
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>,
+		VArg: EncodeLike<V>,
+	{
+		unhashed::put(&Self::storage_double_map_final_key(k1, k2), &val.borrow())
+	}
+
+	fn remove<KArg1, KArg2>(k1: KArg1, k2: KArg2)
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>,
+	{
+		unhashed::kill(&Self::storage_double_map_final_key(k1, k2))
+	}
+
+	fn remove_prefix<KArg1>(k1: KArg1) where KArg1: EncodeLike<K1> {
+		unhashed::kill_prefix(Self::storage_double_map_final_key1(k1).as_ref())
+	}
+
+	fn mutate<KArg1, KArg2, R, F>(k1: KArg1, k2: KArg2, f: F) -> R
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>,
+		F: FnOnce(&mut Self::Query) -> R,
+	{
+		let final_key = Self::storage_double_map_final_key(k1, k2);
+		let mut val = G::from_optional_value_to_query(unhashed::get(final_key.as_ref()));
+
+		let ret = f(&mut val);
+		match G::from_query_to_optional_value(val) {
+			Some(ref val) => unhashed::put(final_key.as_ref(), val),
+			None => unhashed::kill(final_key.as_ref()),
+		}
+		ret
+	}
+
+	fn append<Items, Item, EncodeLikeItem, KArg1, KArg2>(
+		k1: KArg1,
+		k2: KArg2,
+		items: Items,
+	) -> Result<(), &'static str>
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>,
+		Item: Encode,
+		EncodeLikeItem: EncodeLike<Item>,
+		V: EncodeAppend<Item=Item>,
+		Items: IntoIterator<Item=EncodeLikeItem>,
+		Items::IntoIter: ExactSizeIterator
+	{
+		let final_key = Self::storage_double_map_final_key(k1, k2);
+
+		let encoded_value = unhashed::get_raw(&final_key)
+			.unwrap_or_else(|| {
+				match G::from_query_to_optional_value(G::from_optional_value_to_query(None)) {
+					Some(value) => value.encode(),
+					None => vec![],
+				}
+			});
+
+		let new_val = V::append_or_new(
+			encoded_value,
+			items,
+		).map_err(|_| "Could not append given item")?;
+		unhashed::put_raw(&final_key, &new_val);
+
+		Ok(())
+	}
+
+	fn append_or_insert<Items, Item, EncodeLikeItem, KArg1, KArg2>(
+		k1: KArg1,
+		k2: KArg2,
+		items: Items,
+	)
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>,
+		Item: Encode,
+		EncodeLikeItem: EncodeLike<Item>,
+		V: EncodeAppend<Item=Item>,
+		Items: IntoIterator<Item=EncodeLikeItem> + Clone + EncodeLike<V>,
+		Items::IntoIter: ExactSizeIterator
+	{
+		Self::append(Ref::from(&k1), Ref::from(&k2), items.clone())
+			.unwrap_or_else(|_| Self::insert(k1, k2, items));
+	}
+}

substrate/palette/support/src/storage/generator/linked_map.rs

@@ -0,0 +1,467 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+use codec::{FullCodec, Encode, Decode, EncodeLike, Ref};
+use crate::{storage::{self, unhashed}, hash::StorageHasher, traits::Len};
+use rstd::marker::PhantomData;
+
+/// Generator for `StorageLinkedMap` used by `decl_storage`.
+///
+/// # Mapping of keys to a storage path
+///
+/// The key for the head of the map is stored at one fixed path:
+/// ```nocompile
+/// Hasher(head_key)
+/// ```
+///
+/// For each key, the value stored under that key is appended with a
+/// [`Linkage`](struct.Linkage.html) (which hold previous and next key) at the path:
+/// ```nocompile
+/// Hasher(prefix ++ key)
+/// ```
+///
+/// Enumeration is done by getting the head of the linked map and then iterating getting the
+/// value and linkage stored at the key until the found linkage has no next key.
+///
+/// # Warning
+///
+/// If the keys are not trusted (e.g. can be set by a user), a cryptographic `hasher` such as
+/// `blake2_256` must be used. Otherwise, other values in storage can be compromised.
+pub trait StorageLinkedMap<K: FullCodec, V: FullCodec> {
+	/// The type that get/take returns.
+	type Query;
+
+	/// Hasher used to insert into storage.
+	type Hasher: StorageHasher;
+
+	/// The family of key formats used for this map.
+	type KeyFormat: KeyFormat<Hasher=Self::Hasher>;
+
+	/// Prefix used to prepend each key.
+	fn prefix() -> &'static [u8];
+
+	/// The head key of the linked-map.
+	fn head_key() -> &'static [u8] {
+		<Self::KeyFormat as KeyFormat>::head_key()
+	}
+
+	/// Convert an optional value retrieved from storage to the type queried.
+	fn from_optional_value_to_query(v: Option<V>) -> Self::Query;
+
+	/// Convert a query to an optional value into storage.
+	fn from_query_to_optional_value(v: Self::Query) -> Option<V>;
+
+	/// Generate the full key used in top storage.
+	fn storage_linked_map_final_key<KeyArg>(key: KeyArg) -> <Self::Hasher as StorageHasher>::Output
+	where
+		KeyArg: EncodeLike<K>,
+	{
+		<Self::KeyFormat as KeyFormat>::storage_linked_map_final_key::<KeyArg>(Self::prefix(), &key)
+	}
+
+	/// Generate the hashed key for head
+	fn storage_linked_map_final_head_key() -> <Self::Hasher as StorageHasher>::Output {
+		<Self::KeyFormat as KeyFormat>::storage_linked_map_final_head_key()
+	}
+}
+
+/// A type-abstracted key format used for a family of linked-map types.
+pub trait KeyFormat {
+	type Hasher: StorageHasher;
+
+	/// Key used to store linked map head.
+	fn head_key() -> &'static [u8];
+
+	/// Generate the full key used in top storage.
+	fn storage_linked_map_final_key<K>(prefix: &[u8], key: &K)
+		-> <Self::Hasher as StorageHasher>::Output
+	where
+		K: Encode,
+	{
+		let mut final_key = prefix.to_vec();
+		key.encode_to(&mut final_key);
+		<Self::Hasher as StorageHasher>::hash(&final_key)
+	}
+
+	fn storage_linked_map_final_head_key()
+		-> <Self::Hasher as StorageHasher>::Output
+	{
+		<Self::Hasher as StorageHasher>::hash(Self::head_key())
+	}
+}
+
+/// Linkage data of an element (it's successor and predecessor)
+#[derive(Encode, Decode)]
+pub struct Linkage<Key> {
+	/// Previous element key in storage (None for the first element)
+	pub previous: Option<Key>,
+	/// Next element key in storage (None for the last element)
+	pub next: Option<Key>,
+}
+
+impl<Key> Default for Linkage<Key> {
+	fn default() -> Self {
+		Self {
+			previous: None,
+			next: None,
+		}
+	}
+}
+
+// Encode like a linkage.
+#[derive(Encode)]
+struct EncodeLikeLinkage<PKey: EncodeLike<Key>, NKey: EncodeLike<Key>, Key: Encode> {
+	// Previous element key in storage (None for the first element)
+	previous: Option<PKey>,
+	// Next element key in storage (None for the last element)
+	next: Option<NKey>,
+	// The key of the linkage this type encode to
+	phantom: core::marker::PhantomData<Key>,
+}
+
+/// A key-value pair iterator for enumerable map.
+pub struct Enumerator<K, V, F> {
+	next: Option<K>,
+	prefix: &'static [u8],
+	_phantom: PhantomData<(V, F)>,
+}
+
+impl<K, V, F> Enumerator<K, V, F> {
+	/// Create an explicit enumerator for testing.
+	#[cfg(test)]
+	pub fn from_head(head: K, prefix: &'static [u8]) -> Self {
+		Enumerator {
+			next: Some(head),
+			prefix,
+			_phantom: Default::default(),
+		}
+	}
+}
+
+impl<K, V, F> Iterator for Enumerator<K, V, F>
+where
+	K: FullCodec,
+	V: FullCodec,
+	F: KeyFormat,
+{
+	type Item = (K, V);
+
+	fn next(&mut self) -> Option<Self::Item> {
+		let next = self.next.take()?;
+
+		let (val, linkage): (V, Linkage<K>) = {
+			let next_full_key = F::storage_linked_map_final_key(self.prefix, &next);
+			read_with_linkage::<K, V>(next_full_key.as_ref())
+				.expect("previous/next only contains existing entries;
+						we enumerate using next; entry exists; qed")
+		};
+
+		self.next = linkage.next;
+		Some((next, val))
+	}
+}
+
+/// Update linkage when this element is removed.
+///
+/// Takes care of updating previous and next elements points
+/// as well as updates head if the element is first or last.
+fn remove_linkage<K, V, F>(linkage: Linkage<K>, prefix: &[u8])
+where
+	K: FullCodec,
+	V: FullCodec,
+	F: KeyFormat,
+{
+	let next_key = linkage.next.as_ref()
+		.map(|k| F::storage_linked_map_final_key(prefix, k))
+		.map(|x| x.as_ref().to_vec());
+	let prev_key = linkage.previous.as_ref()
+		.map(|k| F::storage_linked_map_final_key(prefix, k))
+		.map(|x| x.as_ref().to_vec());
+
+	if let Some(prev_key) = prev_key {
+		// Retrieve previous element and update `next`
+		let mut res = read_with_linkage::<K, V>(prev_key.as_ref())
+			.expect("Linkage is updated in case entry is removed;
+					it always points to existing keys; qed");
+		res.1.next = linkage.next;
+		unhashed::put(prev_key.as_ref(), &res);
+	} else {
+		// we were first so let's update the head
+		write_head::<&K, K, F>(linkage.next.as_ref());
+	}
+	if let Some(next_key) = next_key {
+		// Update previous of next element
+		let mut res = read_with_linkage::<K, V>(next_key.as_ref())
+			.expect("Linkage is updated in case entry is removed;
+					it always points to existing keys; qed");
+		res.1.previous = linkage.previous;
+		unhashed::put(next_key.as_ref(), &res);
+	}
+}
+
+/// Read the contained data and its linkage.
+pub(super) fn read_with_linkage<K, V>(key: &[u8]) -> Option<(V, Linkage<K>)>
+where
+	K: Decode,
+	V: Decode,
+{
+	unhashed::get(key)
+}
+
+/// Generate linkage for newly inserted element.
+///
+/// Takes care of updating head and previous head's pointer.
+pub(super) fn new_head_linkage<KeyArg, K, V, F>(key: KeyArg, prefix: &[u8]) -> Linkage<K>
+where
+	KeyArg: EncodeLike<K>,
+	K: FullCodec,
+	V: FullCodec,
+	F: KeyFormat,
+{
+	if let Some(head) = read_head::<K, F>() {
+		// update previous head predecessor
+		{
+			let head_key = F::storage_linked_map_final_key(prefix, &head);
+			let (data, linkage) = read_with_linkage::<K, V>(head_key.as_ref())
+				.expect("head is set when first element is inserted
+						and unset when last element is removed;
+						if head is Some then it points to existing key; qed");
+			let new_linkage = EncodeLikeLinkage::<_, _, K> {
+				previous: Some(Ref::from(&key)),
+				next: linkage.next.as_ref(),
+				phantom: Default::default(),
+			};
+			unhashed::put(head_key.as_ref(), &(data, new_linkage));
+		}
+		// update to current head
+		write_head::<_, _, F>(Some(key));
+		// return linkage with pointer to previous head
+		let mut linkage = Linkage::default();
+		linkage.next = Some(head);
+		linkage
+	} else {
+		// we are first - update the head and produce empty linkage
+		write_head::<_, _, F>(Some(key));
+		Linkage::default()
+	}
+}
+
+/// Read current head pointer.
+pub(crate) fn read_head<K, F>() -> Option<K>
+where
+	K: Decode,
+	F: KeyFormat,
+{
+	unhashed::get(F::storage_linked_map_final_head_key().as_ref())
+}
+
+/// Overwrite current head pointer.
+///
+/// If `None` is given head is removed from storage.
+pub(super) fn write_head<KeyArg, K, F>(head: Option<KeyArg>)
+where
+	KeyArg: EncodeLike<K>,
+	K: FullCodec,
+	F: KeyFormat,
+{
+	match head.as_ref() {
+		Some(head) => unhashed::put(F::storage_linked_map_final_head_key().as_ref(), head),
+		None => unhashed::kill(F::storage_linked_map_final_head_key().as_ref()),
+	}
+}
+
+impl<K, V, G> storage::StorageLinkedMap<K, V> for G
+where
+	K: FullCodec,
+	V: FullCodec,
+	G: StorageLinkedMap<K, V>,
+{
+	type Query = G::Query;
+
+	type Enumerator = Enumerator<K, V, G::KeyFormat>;
+
+	fn exists<KeyArg: EncodeLike<K>>(key: KeyArg) -> bool {
+		unhashed::exists(Self::storage_linked_map_final_key(key).as_ref())
+	}
+
+	fn get<KeyArg: EncodeLike<K>>(key: KeyArg) -> Self::Query {
+		let val = unhashed::get(Self::storage_linked_map_final_key(key).as_ref());
+		G::from_optional_value_to_query(val)
+	}
+
+	fn swap<KeyArg1: EncodeLike<K>, KeyArg2: EncodeLike<K>>(key1: KeyArg1, key2: KeyArg2) {
+		let prefix = Self::prefix();
+		let final_key1 = Self::storage_linked_map_final_key(Ref::from(&key1));
+		let final_key2 = Self::storage_linked_map_final_key(Ref::from(&key2));
+		let full_value_1 = read_with_linkage::<K, V>(final_key1.as_ref());
+		let full_value_2 = read_with_linkage::<K, V>(final_key2.as_ref());
+
+		match (full_value_1, full_value_2) {
+			// Just keep linkage in order and only swap values.
+			(Some((value1, linkage1)), Some((value2, linkage2))) => {
+				unhashed::put(final_key1.as_ref(), &(value2, linkage1));
+				unhashed::put(final_key2.as_ref(), &(value1, linkage2));
+			}
+			// Remove key and insert the new one.
+			(Some((value, _linkage)), None) => {
+				Self::remove(key1);
+				let linkage = new_head_linkage::<_, _, V, G::KeyFormat>(key2, prefix);
+				unhashed::put(final_key2.as_ref(), &(value, linkage));
+			}
+			// Remove key and insert the new one.
+			(None, Some((value, _linkage))) => {
+				Self::remove(key2);
+				let linkage = new_head_linkage::<_, _, V, G::KeyFormat>(key1, prefix);
+				unhashed::put(final_key1.as_ref(), &(value, linkage));
+			}
+			// No-op.
+			(None, None) => (),
+		}
+	}
+
+	fn insert<KeyArg: EncodeLike<K>, ValArg: EncodeLike<V>>(key: KeyArg, val: ValArg) {
+		let final_key = Self::storage_linked_map_final_key(Ref::from(&key));
+		let linkage = match read_with_linkage::<_, V>(final_key.as_ref()) {
+			// overwrite but reuse existing linkage
+			Some((_data, linkage)) => linkage,
+			// create new linkage
+			None => new_head_linkage::<_, _, V, G::KeyFormat>(key, Self::prefix()),
+		};
+		unhashed::put(final_key.as_ref(), &(val, linkage))
+	}
+
+	fn remove<KeyArg: EncodeLike<K>>(key: KeyArg) {
+		G::take(key);
+	}
+
+	fn mutate<KeyArg: EncodeLike<K>, R, F: FnOnce(&mut Self::Query) -> R>(key: KeyArg, f: F) -> R {
+		let final_key = Self::storage_linked_map_final_key(Ref::from(&key));
+
+		let (mut val, _linkage) = read_with_linkage::<K, V>(final_key.as_ref())
+			.map(|(data, linkage)| (G::from_optional_value_to_query(Some(data)), Some(linkage)))
+			.unwrap_or_else(|| (G::from_optional_value_to_query(None), None));
+
+		let ret = f(&mut val);
+		match G::from_query_to_optional_value(val) {
+			Some(ref val) => G::insert(key, val),
+			None => G::remove(key),
+		}
+		ret
+	}
+
+	fn take<KeyArg: EncodeLike<K>>(key: KeyArg) -> Self::Query {
+		let final_key = Self::storage_linked_map_final_key(key);
+
+		let full_value: Option<(V, Linkage<K>)> = unhashed::take(final_key.as_ref());
+
+		let value = full_value.map(|(data, linkage)| {
+			remove_linkage::<K, V, G::KeyFormat>(linkage, Self::prefix());
+			data
+		});
+
+		G::from_optional_value_to_query(value)
+	}
+
+	fn enumerate() -> Self::Enumerator {
+		Enumerator::<_, _, G::KeyFormat> {
+			next: read_head::<_, G::KeyFormat>(),
+			prefix: Self::prefix(),
+			_phantom: Default::default(),
+		}
+	}
+
+	fn head() -> Option<K> {
+		read_head::<_, G::KeyFormat>()
+	}
+
+	fn decode_len<KeyArg: EncodeLike<K>>(key: KeyArg) -> Result<usize, &'static str>
+		where V: codec::DecodeLength + Len
+	{
+		let key = Self::storage_linked_map_final_key(key);
+		if let Some(v) = unhashed::get_raw(key.as_ref()) {
+			<V as codec::DecodeLength>::len(&v).map_err(|e| e.what())
+		} else {
+			let len = G::from_query_to_optional_value(G::from_optional_value_to_query(None))
+				.map(|v| v.len())
+				.unwrap_or(0);
+
+			Ok(len)
+		}
+	}
+
+	fn translate<K2, V2, TK, TV>(translate_key: TK, translate_val: TV) -> Result<(), Option<K2>>
+		where K2: FullCodec + Clone, V2: Decode, TK: Fn(K2) -> K, TV: Fn(V2) -> V
+	{
+		let head_key = read_head::<K2, G::KeyFormat>().ok_or(None)?;
+		let prefix = G::prefix();
+
+		let mut last_key = None;
+		let mut current_key = head_key.clone();
+
+		write_head::<&K, K, G::KeyFormat>(Some(&translate_key(head_key)));
+
+		let translate_linkage = |old: Linkage<K2>| -> Linkage<K> {
+			Linkage {
+				previous: old.previous.map(&translate_key),
+				next: old.next.map(&translate_key),
+			}
+		};
+
+		loop {
+			let old_raw_key = G::KeyFormat::storage_linked_map_final_key(prefix, &current_key);
+			let x = unhashed::take(old_raw_key.as_ref());
+			let (val, linkage): (V2, Linkage<K2>) = match x {
+				Some(v) => v,
+				None => {
+					// we failed to read value and linkage. Update the last key's linkage
+					// to end the map early, since it's impossible to iterate further.
+					if let Some(last_key) = last_key {
+						let last_raw_key = G::storage_linked_map_final_key(&last_key);
+						if let Some((val, mut linkage))
+							= read_with_linkage::<K, V>(last_raw_key.as_ref())
+						{
+							// defensive: should always happen, since it was just written
+							// in the last iteration of the loop.
+							linkage.next = None;
+							unhashed::put(last_raw_key.as_ref(), &(&val, &linkage));
+						}
+					}
+
+					return Err(Some(current_key));
+				}
+			};
+			let next = linkage.next.clone();
+
+			let val = translate_val(val);
+			let linkage = translate_linkage(linkage);
+
+			// and write in the value and linkage under the new key.
+			let new_key = translate_key(current_key.clone());
+			let new_raw_key = G::storage_linked_map_final_key(&new_key);
+			unhashed::put(new_raw_key.as_ref(), &(&val, &linkage));
+
+			match next {
+				None => break,
+				Some(next) => {
+					last_key = Some(new_key);
+					current_key = next
+				},
+			}
+		}
+
+		Ok(())
+	}
+}

substrate/palette/support/src/storage/generator/map.rs

@@ -0,0 +1,172 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+#[cfg(not(feature = "std"))]
+use rstd::prelude::*;
+use rstd::borrow::Borrow;
+use codec::{FullCodec, FullEncode, Encode, EncodeLike, Ref, EncodeAppend};
+use crate::{storage::{self, unhashed}, hash::StorageHasher, traits::Len};
+
+/// Generator for `StorageMap` used by `decl_storage`.
+///
+/// For each key value is stored at:
+/// ```nocompile
+/// Hasher(prefix ++ key)
+/// ```
+///
+/// # Warning
+///
+/// If the keys are not trusted (e.g. can be set by a user), a cryptographic `hasher` such as
+/// `blake2_256` must be used.  Otherwise, other values in storage can be compromised.
+pub trait StorageMap<K: FullEncode, V: FullCodec> {
+	/// The type that get/take returns.
+	type Query;
+
+	/// Hasher used to insert into storage.
+	type Hasher: StorageHasher;
+
+	/// Prefix used to prepend each key.
+	fn prefix() -> &'static [u8];
+
+	/// Convert an optional value retrieved from storage to the type queried.
+	fn from_optional_value_to_query(v: Option<V>) -> Self::Query;
+
+	/// Convert a query to an optional value into storage.
+	fn from_query_to_optional_value(v: Self::Query) -> Option<V>;
+
+	/// Generate the full key used in top storage.
+	fn storage_map_final_key<KeyArg>(key: KeyArg) -> <Self::Hasher as StorageHasher>::Output
+	where
+		KeyArg: EncodeLike<K>,
+	{
+		let mut final_key = Self::prefix().to_vec();
+		key.borrow().encode_to(&mut final_key);
+		Self::Hasher::hash(&final_key)
+	}
+}
+
+impl<K: FullEncode, V: FullCodec, G: StorageMap<K, V>> storage::StorageMap<K, V> for G {
+	type Query = G::Query;
+
+	fn hashed_key_for<KeyArg: EncodeLike<K>>(key: KeyArg) -> Vec<u8> {
+		Self::storage_map_final_key(key).as_ref().to_vec()
+	}
+
+	fn swap<KeyArg1: EncodeLike<K>, KeyArg2: EncodeLike<K>>(key1: KeyArg1, key2: KeyArg2) {
+		let k1 = Self::storage_map_final_key(key1);
+		let k2 = Self::storage_map_final_key(key2);
+
+		let v1 = unhashed::get_raw(k1.as_ref());
+		if let Some(val) = unhashed::get_raw(k2.as_ref()) {
+			unhashed::put_raw(k1.as_ref(), &val);
+		} else {
+			unhashed::kill(k1.as_ref())
+		}
+		if let Some(val) = v1 {
+			unhashed::put_raw(k2.as_ref(), &val);
+		} else {
+			unhashed::kill(k2.as_ref())
+		}
+	}
+
+	fn exists<KeyArg: EncodeLike<K>>(key: KeyArg) -> bool {
+		unhashed::exists(Self::storage_map_final_key(key).as_ref())
+	}
+
+	fn get<KeyArg: EncodeLike<K>>(key: KeyArg) -> Self::Query {
+		G::from_optional_value_to_query(unhashed::get(Self::storage_map_final_key(key).as_ref()))
+	}
+
+	fn insert<KeyArg: EncodeLike<K>, ValArg: EncodeLike<V>>(key: KeyArg, val: ValArg) {
+		unhashed::put(Self::storage_map_final_key(key).as_ref(), &val.borrow())
+	}
+
+	fn remove<KeyArg: EncodeLike<K>>(key: KeyArg) {
+		unhashed::kill(Self::storage_map_final_key(key).as_ref())
+	}
+
+	fn mutate<KeyArg: EncodeLike<K>, R, F: FnOnce(&mut Self::Query) -> R>(key: KeyArg, f: F) -> R {
+		let final_key = Self::storage_map_final_key(key);
+		let mut val = G::from_optional_value_to_query(unhashed::get(final_key.as_ref()));
+
+		let ret = f(&mut val);
+		match G::from_query_to_optional_value(val) {
+			Some(ref val) => unhashed::put(final_key.as_ref(), &val.borrow()),
+			None => unhashed::kill(final_key.as_ref()),
+		}
+		ret
+	}
+
+	fn take<KeyArg: EncodeLike<K>>(key: KeyArg) -> Self::Query {
+		let key = Self::storage_map_final_key(key);
+		let value = unhashed::take(key.as_ref());
+		G::from_optional_value_to_query(value)
+	}
+
+	fn append<Items, Item, EncodeLikeItem, KeyArg>(key: KeyArg, items: Items) -> Result<(), &'static str>
+	where
+		KeyArg: EncodeLike<K>,
+		Item: Encode,
+		EncodeLikeItem: EncodeLike<Item>,
+		V: EncodeAppend<Item=Item>,
+		Items: IntoIterator<Item=EncodeLikeItem>,
+		Items::IntoIter: ExactSizeIterator,
+	{
+		let key = Self::storage_map_final_key(key);
+		let encoded_value = unhashed::get_raw(key.as_ref())
+			.unwrap_or_else(|| {
+				match G::from_query_to_optional_value(G::from_optional_value_to_query(None)) {
+					Some(value) => value.encode(),
+					None => vec![],
+				}
+			});
+
+		let new_val = V::append_or_new(
+			encoded_value,
+			items,
+		).map_err(|_| "Could not append given item")?;
+		unhashed::put_raw(key.as_ref(), &new_val);
+		Ok(())
+	}
+
+	fn append_or_insert<Items, Item, EncodeLikeItem, KeyArg>(key: KeyArg, items: Items)
+	where
+		KeyArg: EncodeLike<K>,
+		Item: Encode,
+		EncodeLikeItem: EncodeLike<Item>,
+		V: EncodeAppend<Item=Item>,
+		Items: IntoIterator<Item=EncodeLikeItem> + Clone + EncodeLike<V>,
+		Items::IntoIter: ExactSizeIterator,
+	{
+		Self::append(Ref::from(&key), items.clone())
+			.unwrap_or_else(|_| Self::insert(key, items));
+	}
+
+	fn decode_len<KeyArg: EncodeLike<K>>(key: KeyArg) -> Result<usize, &'static str>
+		where V: codec::DecodeLength + Len
+	{
+		let key = Self::storage_map_final_key(key);
+		if let Some(v) = unhashed::get_raw(key.as_ref()) {
+			<V as codec::DecodeLength>::len(&v).map_err(|e| e.what())
+		} else {
+			let len = G::from_query_to_optional_value(G::from_optional_value_to_query(None))
+				.map(|v| v.len())
+				.unwrap_or(0);
+
+			Ok(len)
+		}
+	}
+}

substrate/palette/support/src/storage/generator/mod.rs

@@ -0,0 +1,132 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Generators are a set of trait on which storage traits are implemented.
+//!
+//! (i.e. implementing the generator for StorageValue on a type will automatically derive the
+//! implementation of StorageValue for this type).
+//!
+//! They are used by `decl_storage`.
+
+mod linked_map;
+mod map;
+mod double_map;
+mod value;
+
+pub use linked_map::{StorageLinkedMap, Enumerator, Linkage, KeyFormat as LinkedMapKeyFormat};
+pub use map::StorageMap;
+pub use double_map::StorageDoubleMap;
+pub use value::StorageValue;
+
+
+#[cfg(test)]
+#[allow(dead_code)]
+mod tests {
+	use runtime_io::TestExternalities;
+	use codec::{Encode, Decode};
+	use crate::storage::{unhashed, generator::{StorageValue, StorageLinkedMap}};
+
+	struct Runtime {}
+	pub trait Trait {
+		type Origin;
+		type BlockNumber;
+	}
+
+	impl Trait for Runtime {
+		type Origin = u32;
+		type BlockNumber = u32;
+	}
+
+	decl_module! {
+		pub struct Module<T: Trait> for enum Call where origin: T::Origin {}
+	}
+
+	#[derive(Encode, Decode, Clone, Debug, Eq, PartialEq)]
+	struct NumberNumber {
+		a: u32,
+		b: u32,
+	}
+
+	crate::decl_storage! {
+		trait Store for Module<T: Trait> as Runtime {
+			Value get(fn value) config(): (u64, u64);
+			NumberMap: linked_map NumberNumber => u64;
+		}
+	}
+
+	#[test]
+	fn value_translate_works() {
+		let t = GenesisConfig::default().build_storage().unwrap();
+		TestExternalities::new(t).execute_with(|| {
+			// put the old value `1111u32` in the storage.
+			let key = Value::storage_value_final_key();
+			unhashed::put_raw(&key, &1111u32.encode());
+
+			// translate
+			let translate_fn = |old: Option<u32>| -> Option<(u64, u64)> {
+				old.map(|o| (o.into(), (o*2).into()))
+			};
+			let _ = Value::translate(translate_fn);
+
+			// new storage should be `(1111, 1111 * 2)`
+			assert_eq!(Value::get(), (1111, 2222));
+		})
+	}
+
+	#[test]
+	fn linked_map_translate_works() {
+		use super::linked_map::{self, Enumerator, KeyFormat};
+
+		type Format = <NumberMap as StorageLinkedMap<NumberNumber, u64>>::KeyFormat;
+
+		let t = GenesisConfig::default().build_storage().unwrap();
+		TestExternalities::new(t).execute_with(|| {
+			let prefix = NumberMap::prefix();
+
+			// start with a map of u32 -> u32.
+			for i in 0u32..100u32 {
+				let final_key = <Format as KeyFormat>::storage_linked_map_final_key(
+					prefix, &i,
+				);
+
+				let linkage = linked_map::new_head_linkage::<_, u32, u32, Format>(&i, prefix);
+				unhashed::put(final_key.as_ref(), &(&i, linkage));
+			}
+
+			let head = linked_map::read_head::<u32, Format>().unwrap();
+
+			assert_eq!(
+				Enumerator::<u32, u32, Format>::from_head(head, prefix).collect::<Vec<_>>(),
+				(0..100).rev().map(|x| (x, x)).collect::<Vec<_>>(),
+			);
+
+			// do translation.
+			NumberMap::translate(
+				|k: u32| NumberNumber { a: k, b: k },
+				|v: u32| (v as u64) << 32 | v as u64,
+			).unwrap();
+
+			assert!(linked_map::read_head::<NumberNumber, Format>().is_some());
+			assert_eq!(
+				NumberMap::enumerate().collect::<Vec<_>>(),
+				(0..100u32).rev().map(|x| (
+					NumberNumber { a: x, b: x },
+					(x as u64) << 32 | x as u64,
+				)).collect::<Vec<_>>(),
+			);
+		})
+	}
+}

substrate/palette/support/src/storage/generator/value.rs

@@ -0,0 +1,171 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+#[cfg(not(feature = "std"))]
+use rstd::prelude::*;
+use codec::{FullCodec, Encode, EncodeAppend, EncodeLike, Decode};
+use crate::{storage::{self, unhashed}, hash::{Twox128, StorageHasher}, traits::Len};
+
+/// Generator for `StorageValue` used by `decl_storage`.
+///
+/// Value is stored at:
+/// ```nocompile
+/// Twox128(unhashed_key)
+/// ```
+pub trait StorageValue<T: FullCodec> {
+	/// The type that get/take returns.
+	type Query;
+
+	/// Unhashed key used in storage
+	fn unhashed_key() -> &'static [u8];
+
+	/// Convert an optional value retrieved from storage to the type queried.
+	fn from_optional_value_to_query(v: Option<T>) -> Self::Query;
+
+	/// Convert a query to an optional value into storage.
+	fn from_query_to_optional_value(v: Self::Query) -> Option<T>;
+
+	/// Generate the full key used in top storage.
+	fn storage_value_final_key() -> [u8; 16] {
+		Twox128::hash(Self::unhashed_key())
+	}
+}
+
+impl<T: FullCodec, G: StorageValue<T>> storage::StorageValue<T> for G {
+	type Query = G::Query;
+
+	fn hashed_key() -> [u8; 16] {
+		Self::storage_value_final_key()
+	}
+
+	fn exists() -> bool {
+		unhashed::exists(&Self::storage_value_final_key())
+	}
+
+	fn get() -> Self::Query {
+		let value = unhashed::get(&Self::storage_value_final_key());
+		G::from_optional_value_to_query(value)
+	}
+
+	fn translate<O: Decode, F: FnOnce(Option<O>) -> Option<T>>(f: F) -> Result<Option<T>, ()> {
+		let key = Self::storage_value_final_key();
+
+		// attempt to get the length directly.
+		let maybe_old = match unhashed::get_raw(&key) {
+			Some(old_data) => Some(O::decode(&mut &old_data[..]).map_err(|_| ())?),
+			None => None,
+		};
+		let maybe_new = f(maybe_old);
+		if let Some(new) = maybe_new.as_ref() {
+			new.using_encoded(|d| unhashed::put_raw(&key, d));
+		} else {
+			unhashed::kill(&key);
+		}
+		Ok(maybe_new)
+	}
+
+	fn put<Arg: EncodeLike<T>>(val: Arg) {
+		unhashed::put(&Self::storage_value_final_key(), &val)
+	}
+
+	fn kill() {
+		unhashed::kill(&Self::storage_value_final_key())
+	}
+
+	fn mutate<R, F: FnOnce(&mut G::Query) -> R>(f: F) -> R {
+		let mut val = G::get();
+
+		let ret = f(&mut val);
+		match G::from_query_to_optional_value(val) {
+			Some(ref val) => G::put(val),
+			None => G::kill(),
+		}
+		ret
+	}
+
+	fn take() -> G::Query {
+		let key = Self::storage_value_final_key();
+		let value = unhashed::get(&key);
+		if value.is_some() {
+			unhashed::kill(&key)
+		}
+		G::from_optional_value_to_query(value)
+	}
+
+	/// Append the given items to the value in the storage.
+	///
+	/// `T` is required to implement `codec::EncodeAppend`.
+	fn append<Items, Item, EncodeLikeItem>(items: Items) -> Result<(), &'static str>
+	where
+		Item: Encode,
+		EncodeLikeItem: EncodeLike<Item>,
+		T: EncodeAppend<Item=Item>,
+		Items: IntoIterator<Item=EncodeLikeItem>,
+		Items::IntoIter: ExactSizeIterator,
+	{
+		let key = Self::storage_value_final_key();
+		let encoded_value = unhashed::get_raw(&key)
+			.unwrap_or_else(|| {
+				match G::from_query_to_optional_value(G::from_optional_value_to_query(None)) {
+					Some(value) => value.encode(),
+					None => vec![],
+				}
+			});
+
+		let new_val = T::append_or_new(
+			encoded_value,
+			items,
+		).map_err(|_| "Could not append given item")?;
+		unhashed::put_raw(&key, &new_val);
+		Ok(())
+	}
+
+	/// Safely append the given items to the value in the storage. If a codec error occurs, then the
+	/// old (presumably corrupt) value is replaced with the given `items`.
+	///
+	/// `T` is required to implement `codec::EncodeAppend`.
+	fn append_or_put<Items, Item, EncodeLikeItem>(items: Items) where
+		Item: Encode,
+		EncodeLikeItem: EncodeLike<Item>,
+		T: EncodeAppend<Item=Item>,
+		Items: IntoIterator<Item=EncodeLikeItem> + Clone + EncodeLike<T>,
+		Items::IntoIter: ExactSizeIterator
+	{
+		Self::append(items.clone()).unwrap_or_else(|_| Self::put(items));
+	}
+
+	/// Read the length of the value in a fast way, without decoding the entire value.
+	///
+	/// `T` is required to implement `Codec::DecodeLength`.
+	///
+	/// Note that `0` is returned as the default value if no encoded value exists at the given key.
+	/// Therefore, this function cannot be used as a sign of _existence_. use the `::exists()`
+	/// function for this purpose.
+	fn decode_len() -> Result<usize, &'static str> where T: codec::DecodeLength, T: Len {
+		let key = Self::storage_value_final_key();
+
+		// attempt to get the length directly.
+		if let Some(k) = unhashed::get_raw(&key) {
+			<T as codec::DecodeLength>::len(&k).map_err(|e| e.what())
+		} else {
+			let len = G::from_query_to_optional_value(G::from_optional_value_to_query(None))
+				.map(|v| v.len())
+				.unwrap_or(0);
+
+			Ok(len)
+		}
+	}
+}

substrate/palette/support/src/storage/hashed.rs

@@ -0,0 +1,155 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Operation on runtime storage using hashed keys.
+
+use super::unhashed;
+use rstd::prelude::*;
+use codec::{Encode, Decode};
+
+/// Return the value of the item in storage under `key`, or `None` if there is no explicit entry.
+pub fn get<T, HashFn, R>(hash: &HashFn, key: &[u8]) -> Option<T>
+where
+	T: Decode + Sized,
+	HashFn: Fn(&[u8]) -> R,
+	R: AsRef<[u8]>,
+{
+	unhashed::get(&hash(key).as_ref())
+}
+
+/// Return the value of the item in storage under `key`, or the type's default if there is no
+/// explicit entry.
+pub fn get_or_default<T, HashFn, R>(hash: &HashFn, key: &[u8]) -> T
+where
+	T: Decode + Sized + Default,
+	HashFn: Fn(&[u8]) -> R,
+	R: AsRef<[u8]>,
+{
+	unhashed::get_or_default(&hash(key).as_ref())
+}
+
+/// Return the value of the item in storage under `key`, or `default_value` if there is no
+/// explicit entry.
+pub fn get_or<T, HashFn, R>(hash: &HashFn, key: &[u8], default_value: T) -> T
+where
+	T: Decode + Sized,
+	HashFn: Fn(&[u8]) -> R,
+	R: AsRef<[u8]>,
+{
+	unhashed::get_or(&hash(key).as_ref(), default_value)
+}
+
+/// Return the value of the item in storage under `key`, or `default_value()` if there is no
+/// explicit entry.
+pub fn get_or_else<T, F, HashFn, R>(hash: &HashFn, key: &[u8], default_value: F) -> T
+where
+	T: Decode + Sized,
+	F: FnOnce() -> T,
+	HashFn: Fn(&[u8]) -> R,
+	R: AsRef<[u8]>,
+{
+	unhashed::get_or_else(&hash(key).as_ref(), default_value)
+}
+
+/// Put `value` in storage under `key`.
+pub fn put<T, HashFn, R>(hash: &HashFn, key: &[u8], value: &T)
+where
+	T: Encode,
+	HashFn: Fn(&[u8]) -> R,
+	R: AsRef<[u8]>,
+{
+	unhashed::put(&hash(key).as_ref(), value)
+}
+
+/// Remove `key` from storage, returning its value if it had an explicit entry or `None` otherwise.
+pub fn take<T, HashFn, R>(hash: &HashFn, key: &[u8]) -> Option<T>
+where
+	T: Decode + Sized,
+	HashFn: Fn(&[u8]) -> R,
+	R: AsRef<[u8]>,
+{
+	unhashed::take(&hash(key).as_ref())
+}
+
+/// Remove `key` from storage, returning its value, or, if there was no explicit entry in storage,
+/// the default for its type.
+pub fn take_or_default<T, HashFn, R>(hash: &HashFn, key: &[u8]) -> T
+where
+	T: Decode + Sized + Default,
+	HashFn: Fn(&[u8]) -> R,
+	R: AsRef<[u8]>,
+{
+	unhashed::take_or_default(&hash(key).as_ref())
+}
+
+/// Return the value of the item in storage under `key`, or `default_value` if there is no
+/// explicit entry. Ensure there is no explicit entry on return.
+pub fn take_or<T, HashFn, R>(hash: &HashFn, key: &[u8], default_value: T) -> T
+where
+	T: Decode + Sized,
+	HashFn: Fn(&[u8]) -> R,
+	R: AsRef<[u8]>,
+{
+	unhashed::take_or(&hash(key).as_ref(), default_value)
+}
+
+/// Return the value of the item in storage under `key`, or `default_value()` if there is no
+/// explicit entry. Ensure there is no explicit entry on return.
+pub fn take_or_else<T, F, HashFn, R>(hash: &HashFn, key: &[u8], default_value: F) -> T
+where
+	T: Decode + Sized,
+	F: FnOnce() -> T,
+	HashFn: Fn(&[u8]) -> R,
+	R: AsRef<[u8]>,
+{
+	unhashed::take_or_else(&hash(key).as_ref(), default_value)
+}
+
+/// Check to see if `key` has an explicit entry in storage.
+pub fn exists<HashFn, R>(hash: &HashFn, key: &[u8]) -> bool
+where
+	HashFn: Fn(&[u8]) -> R,
+	R: AsRef<[u8]>,
+{
+	unhashed::exists(&hash(key).as_ref())
+}
+
+/// Ensure `key` has no explicit entry in storage.
+pub fn kill<HashFn, R>(hash: &HashFn, key: &[u8])
+where
+	HashFn: Fn(&[u8]) -> R,
+	R: AsRef<[u8]>,
+{
+	unhashed::kill(&hash(key).as_ref())
+}
+
+/// Get a Vec of bytes from storage.
+pub fn get_raw<HashFn, R>(hash: &HashFn, key: &[u8]) -> Option<Vec<u8>>
+where
+	HashFn: Fn(&[u8]) -> R,
+	R: AsRef<[u8]>,
+{
+	unhashed::get_raw(&hash(key).as_ref())
+}
+
+/// Put a raw byte slice into storage.
+pub fn put_raw<HashFn, R>(hash: &HashFn, key: &[u8], value: &[u8])
+where
+	HashFn: Fn(&[u8]) -> R,
+	R: AsRef<[u8]>,
+{
+	unhashed::put_raw(&hash(key).as_ref(), value)
+}

substrate/palette/support/src/storage/mod.rs

@@ -0,0 +1,333 @@
+// Copyright 2017-2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Stuff to do with the runtime's storage.
+
+use rstd::prelude::*;
+use codec::{FullCodec, FullEncode, Encode, EncodeAppend, EncodeLike, Decode};
+use crate::traits::Len;
+
+pub mod unhashed;
+pub mod hashed;
+pub mod child;
+pub mod generator;
+
+/// A trait for working with macro-generated storage values under the substrate storage API.
+///
+/// Details on implementation can be found at
+/// [`generator::StorageValue`]
+pub trait StorageValue<T: FullCodec> {
+	/// The type that get/take return.
+	type Query;
+
+	/// Get the storage key.
+	fn hashed_key() -> [u8; 16];
+
+	/// Does the value (explicitly) exist in storage?
+	fn exists() -> bool;
+
+	/// Load the value from the provided storage instance.
+	fn get() -> Self::Query;
+
+	/// Translate a value from some previous type (`O`) to the current type.
+	///
+	/// `f: F` is the translation function.
+	///
+	/// Returns `Err` if the storage item could not be interpreted as the old type, and Ok, along
+	/// with the new value if it could.
+	///
+	/// NOTE: This operates from and to `Option<_>` types; no effort is made to respect the default
+	/// value of the original type.
+	///
+	/// # Warning
+	///
+	/// This function must be used with care, before being updated the storage still contains the
+	/// old type, thus other calls (such as `get`) will fail at decoding it.
+	///
+	/// # Usage
+	///
+	/// This would typically be called inside the module implementation of on_initialize, while
+	/// ensuring **no usage of this storage are made before the call to `on_initialize`**. (More
+	/// precisely prior initialized modules doesn't make use of this storage).
+	fn translate<O: Decode, F: FnOnce(Option<O>) -> Option<T>>(f: F) -> Result<Option<T>, ()>;
+
+	/// Store a value under this key into the provided storage instance.
+	fn put<Arg: EncodeLike<T>>(val: Arg);
+
+	/// Mutate the value
+	fn mutate<R, F: FnOnce(&mut Self::Query) -> R>(f: F) -> R;
+
+	/// Clear the storage value.
+	fn kill();
+
+	/// Take a value from storage, removing it afterwards.
+	fn take() -> Self::Query;
+
+	/// Append the given item to the value in the storage.
+	///
+	/// `T` is required to implement `codec::EncodeAppend`.
+	fn append<Items, Item, EncodeLikeItem>(items: Items) -> Result<(), &'static str>
+	where
+		Item: Encode,
+		EncodeLikeItem: EncodeLike<Item>,
+		T: EncodeAppend<Item=Item>,
+		Items: IntoIterator<Item=EncodeLikeItem>,
+		Items::IntoIter: ExactSizeIterator;
+
+	/// Append the given items to the value in the storage.
+	///
+	/// `T` is required to implement `Codec::EncodeAppend`.
+	///
+	/// Upon any failure, it replaces `items` as the new value (assuming that the previous stored
+	/// data is simply corrupt and no longer usable).
+	///
+	/// ### WARNING
+	///
+	/// use with care; if your use-case is not _exactly_ as what this function is doing,
+	/// you should use append and sensibly handle failure within the runtime code if it happens.
+	fn append_or_put<Items, Item, EncodeLikeItem>(items: Items) where
+		Item: Encode,
+		EncodeLikeItem: EncodeLike<Item>,
+		T: EncodeAppend<Item=Item>,
+		Items: IntoIterator<Item=EncodeLikeItem> + Clone + EncodeLike<T>,
+		Items::IntoIter: ExactSizeIterator;
+
+
+	/// Read the length of the value in a fast way, without decoding the entire value.
+	///
+	/// `T` is required to implement `Codec::DecodeLength`.
+	fn decode_len() -> Result<usize, &'static str>
+		where T: codec::DecodeLength + Len;
+}
+
+/// A strongly-typed map in storage.
+///
+/// Details on implementation can be found at
+/// [`generator::StorageMap`]
+pub trait StorageMap<K: FullEncode, V: FullCodec> {
+	/// The type that get/take return.
+	type Query;
+
+	/// Get the storage key used to fetch a value corresponding to a specific key.
+	fn hashed_key_for<KeyArg: EncodeLike<K>>(key: KeyArg) -> Vec<u8>;
+
+	/// Does the value (explicitly) exist in storage?
+	fn exists<KeyArg: EncodeLike<K>>(key: KeyArg) -> bool;
+
+	/// Load the value associated with the given key from the map.
+	fn get<KeyArg: EncodeLike<K>>(key: KeyArg) -> Self::Query;
+
+	/// Swap the values of two keys.
+	fn swap<KeyArg1: EncodeLike<K>, KeyArg2: EncodeLike<K>>(key1: KeyArg1, key2: KeyArg2);
+
+	/// Store a value to be associated with the given key from the map.
+	fn insert<KeyArg: EncodeLike<K>, ValArg: EncodeLike<V>>(key: KeyArg, val: ValArg);
+
+	/// Remove the value under a key.
+	fn remove<KeyArg: EncodeLike<K>>(key: KeyArg);
+
+	/// Mutate the value under a key.
+	fn mutate<KeyArg: EncodeLike<K>, R, F: FnOnce(&mut Self::Query) -> R>(key: KeyArg, f: F) -> R;
+
+	/// Take the value under a key.
+	fn take<KeyArg: EncodeLike<K>>(key: KeyArg) -> Self::Query;
+
+	/// Append the given items to the value in the storage.
+	///
+	/// `V` is required to implement `codec::EncodeAppend`.
+	fn append<Items, Item, EncodeLikeItem, KeyArg>(key: KeyArg, items: Items) -> Result<(), &'static str>
+	where
+		KeyArg: EncodeLike<K>,
+		Item: Encode,
+		EncodeLikeItem: EncodeLike<Item>,
+		V: EncodeAppend<Item=Item>,
+		Items: IntoIterator<Item=EncodeLikeItem>,
+		Items::IntoIter: ExactSizeIterator;
+
+	/// Safely append the given items to the value in the storage. If a codec error occurs, then the
+	/// old (presumably corrupt) value is replaced with the given `items`.
+	///
+	/// `V` is required to implement `codec::EncodeAppend`.
+	fn append_or_insert<Items, Item, EncodeLikeItem, KeyArg>(key: KeyArg, items: Items)
+	where
+		KeyArg: EncodeLike<K>,
+		Item: Encode,
+		EncodeLikeItem: EncodeLike<Item>,
+		V: EncodeAppend<Item=Item>,
+		Items: IntoIterator<Item=EncodeLikeItem> + Clone + EncodeLike<V>,
+		Items::IntoIter: ExactSizeIterator;
+
+	/// Read the length of the value in a fast way, without decoding the entire value.
+	///
+	/// `T` is required to implement `Codec::DecodeLength`.
+	///
+	/// Note that `0` is returned as the default value if no encoded value exists at the given key.
+	/// Therefore, this function cannot be used as a sign of _existence_. use the `::exists()`
+	/// function for this purpose.
+	fn decode_len<KeyArg: EncodeLike<K>>(key: KeyArg) -> Result<usize, &'static str>
+		where V: codec::DecodeLength + Len;
+}
+
+/// A strongly-typed linked map in storage.
+///
+/// Similar to `StorageMap` but allows to enumerate other elements and doesn't implement append.
+///
+/// Details on implementation can be found at
+/// [`generator::StorageLinkedMap`]
+pub trait StorageLinkedMap<K: FullCodec, V: FullCodec> {
+	/// The type that get/take return.
+	type Query;
+
+	/// The type that iterates over all `(key, value)`.
+	type Enumerator: Iterator<Item = (K, V)>;
+
+	/// Does the value (explicitly) exist in storage?
+	fn exists<KeyArg: EncodeLike<K>>(key: KeyArg) -> bool;
+
+	/// Load the value associated with the given key from the map.
+	fn get<KeyArg: EncodeLike<K>>(key: KeyArg) -> Self::Query;
+
+	/// Swap the values of two keys.
+	fn swap<KeyArg1: EncodeLike<K>, KeyArg2: EncodeLike<K>>(key1: KeyArg1, key2: KeyArg2);
+
+	/// Store a value to be associated with the given key from the map.
+	fn insert<KeyArg: EncodeLike<K>, ValArg: EncodeLike<V>>(key: KeyArg, val: ValArg);
+
+	/// Remove the value under a key.
+	fn remove<KeyArg: EncodeLike<K>>(key: KeyArg);
+
+	/// Mutate the value under a key.
+	fn mutate<KeyArg: EncodeLike<K>, R, F: FnOnce(&mut Self::Query) -> R>(key: KeyArg, f: F) -> R;
+
+	/// Take the value under a key.
+	fn take<KeyArg: EncodeLike<K>>(key: KeyArg) -> Self::Query;
+
+	/// Return current head element.
+	fn head() -> Option<K>;
+
+	/// Enumerate all elements in the map.
+	fn enumerate() -> Self::Enumerator;
+
+	/// Read the length of the value in a fast way, without decoding the entire value.
+	///
+	/// `T` is required to implement `Codec::DecodeLength`.
+	///
+	/// Note that `0` is returned as the default value if no encoded value exists at the given key.
+	/// Therefore, this function cannot be used as a sign of _existence_. use the `::exists()`
+	/// function for this purpose.
+	fn decode_len<KeyArg: EncodeLike<K>>(key: KeyArg) -> Result<usize, &'static str>
+		where V: codec::DecodeLength + Len;
+
+	/// Translate the keys and values from some previous `(K2, V2)` to the current type.
+	///
+	/// `TK` translates keys from the old type, and `TV` translates values.
+	///
+	/// Returns `Err` if the map could not be interpreted as the old type, and Ok if it could.
+	/// The `Err` contains the first key which could not be migrated, or `None` if the
+	/// head of the list could not be read.
+	///
+	/// # Warning
+	///
+	/// This function must be used with care, before being updated the storage still contains the
+	/// old type, thus other calls (such as `get`) will fail at decoding it.
+	///
+	/// # Usage
+	///
+	/// This would typically be called inside the module implementation of on_initialize, while
+	/// ensuring **no usage of this storage are made before the call to `on_initialize`**. (More
+	/// precisely prior initialized modules doesn't make use of this storage).
+	fn translate<K2, V2, TK, TV>(translate_key: TK, translate_val: TV) -> Result<(), Option<K2>>
+		where K2: FullCodec + Clone, V2: Decode, TK: Fn(K2) -> K, TV: Fn(V2) -> V;
+}
+
+/// An implementation of a map with a two keys.
+///
+/// It provides an important ability to efficiently remove all entries
+/// that have a common first key.
+///
+/// Details on implementation can be found at
+/// [`generator::StorageDoubleMap`]
+pub trait StorageDoubleMap<K1: FullEncode, K2: FullEncode, V: FullCodec> {
+	/// The type that get/take returns.
+	type Query;
+
+	fn hashed_key_for<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Vec<u8>
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>;
+
+	fn exists<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> bool
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>;
+
+	fn get<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Self::Query
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>;
+
+	fn take<KArg1, KArg2>(k1: KArg1, k2: KArg2) -> Self::Query
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>;
+
+	fn insert<KArg1, KArg2, VArg>(k1: KArg1, k2: KArg2, val: VArg)
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>,
+		VArg: EncodeLike<V>;
+
+	fn remove<KArg1, KArg2>(k1: KArg1, k2: KArg2)
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>;
+
+	fn remove_prefix<KArg1>(k1: KArg1) where KArg1: ?Sized + EncodeLike<K1>;
+
+	fn mutate<KArg1, KArg2, R, F>(k1: KArg1, k2: KArg2, f: F) -> R
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>,
+		F: FnOnce(&mut Self::Query) -> R;
+
+	fn append<Items, Item, EncodeLikeItem, KArg1, KArg2>(
+		k1: KArg1,
+		k2: KArg2,
+		items: Items,
+	) -> Result<(), &'static str>
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>,
+		Item: Encode,
+		EncodeLikeItem: EncodeLike<Item>,
+		V: EncodeAppend<Item=Item>,
+		Items: IntoIterator<Item=EncodeLikeItem>,
+		Items::IntoIter: ExactSizeIterator;
+
+	fn append_or_insert<Items, Item, EncodeLikeItem, KArg1, KArg2>(
+		k1: KArg1,
+		k2: KArg2,
+		items: Items,
+	)
+	where
+		KArg1: EncodeLike<K1>,
+		KArg2: EncodeLike<K2>,
+		Item: Encode,
+		EncodeLikeItem: EncodeLike<Item>,
+		V: EncodeAppend<Item=Item>,
+		Items: IntoIterator<Item=EncodeLikeItem> + Clone + EncodeLike<V>,
+		Items::IntoIter: ExactSizeIterator;
+}

substrate/palette/support/src/storage/unhashed.rs

@@ -0,0 +1,102 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Operation on unhashed runtime storage.
+
+use rstd::prelude::*;
+use codec::{Encode, Decode};
+
+/// Return the value of the item in storage under `key`, or `None` if there is no explicit entry.
+pub fn get<T: Decode + Sized>(key: &[u8]) -> Option<T> {
+	runtime_io::storage::get(key).map(|val| {
+		Decode::decode(&mut &val[..]).expect("storage is not null, therefore must be a valid type")
+	})
+}
+
+/// Return the value of the item in storage under `key`, or the type's default if there is no
+/// explicit entry.
+pub fn get_or_default<T: Decode + Sized + Default>(key: &[u8]) -> T {
+	get(key).unwrap_or_else(Default::default)
+}
+
+/// Return the value of the item in storage under `key`, or `default_value` if there is no
+/// explicit entry.
+pub fn get_or<T: Decode + Sized>(key: &[u8], default_value: T) -> T {
+	get(key).unwrap_or(default_value)
+}
+
+/// Return the value of the item in storage under `key`, or `default_value()` if there is no
+/// explicit entry.
+pub fn get_or_else<T: Decode + Sized, F: FnOnce() -> T>(key: &[u8], default_value: F) -> T {
+	get(key).unwrap_or_else(default_value)
+}
+
+/// Put `value` in storage under `key`.
+pub fn put<T: Encode + ?Sized>(key: &[u8], value: &T) {
+	value.using_encoded(|slice| runtime_io::storage::set(key, slice));
+}
+
+/// Remove `key` from storage, returning its value if it had an explicit entry or `None` otherwise.
+pub fn take<T: Decode + Sized>(key: &[u8]) -> Option<T> {
+	let r = get(key);
+	if r.is_some() {
+		kill(key);
+	}
+	r
+}
+
+/// Remove `key` from storage, returning its value, or, if there was no explicit entry in storage,
+/// the default for its type.
+pub fn take_or_default<T: Decode + Sized + Default>(key: &[u8]) -> T {
+	take(key).unwrap_or_else(Default::default)
+}
+
+/// Return the value of the item in storage under `key`, or `default_value` if there is no
+/// explicit entry. Ensure there is no explicit entry on return.
+pub fn take_or<T: Decode + Sized>(key: &[u8], default_value: T) -> T {
+	take(key).unwrap_or(default_value)
+}
+
+/// Return the value of the item in storage under `key`, or `default_value()` if there is no
+/// explicit entry. Ensure there is no explicit entry on return.
+pub fn take_or_else<T: Decode + Sized, F: FnOnce() -> T>(key: &[u8], default_value: F) -> T {
+	take(key).unwrap_or_else(default_value)
+}
+
+/// Check to see if `key` has an explicit entry in storage.
+pub fn exists(key: &[u8]) -> bool {
+	runtime_io::storage::read(key, &mut [0;0][..], 0).is_some()
+}
+
+/// Ensure `key` has no explicit entry in storage.
+pub fn kill(key: &[u8]) {
+	runtime_io::storage::clear(key);
+}
+
+/// Ensure keys with the given `prefix` have no entries in storage.
+pub fn kill_prefix(prefix: &[u8]) {
+	runtime_io::storage::clear_prefix(prefix);
+}
+
+/// Get a Vec of bytes from storage.
+pub fn get_raw(key: &[u8]) -> Option<Vec<u8>> {
+	runtime_io::storage::get(key)
+}
+
+/// Put a raw byte slice into storage.
+pub fn put_raw(key: &[u8], value: &[u8]) {
+	runtime_io::storage::set(key, value)
+}

substrate/palette/support/src/traits.rs

@@ -0,0 +1,746 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Traits for SRML.
+//!
+//! NOTE: If you're looking for `parameter_types`, it has moved in to the top-level module.
+
+use rstd::{prelude::*, result, marker::PhantomData, ops::Div, fmt::Debug};
+use codec::{FullCodec, Codec, Encode, Decode};
+use primitives::u32_trait::Value as U32;
+use sr_primitives::{
+	ConsensusEngineId,
+	traits::{MaybeSerializeDeserialize, SimpleArithmetic, Saturating},
+};
+
+/// Anything that can have a `::len()` method.
+pub trait Len {
+	/// Return the length of data type.
+	fn len(&self) -> usize;
+}
+
+impl<T: IntoIterator + Clone,> Len for T where <T as IntoIterator>::IntoIter: ExactSizeIterator {
+	fn len(&self) -> usize {
+		self.clone().into_iter().len()
+	}
+}
+
+/// A trait for querying a single fixed value from a type.
+pub trait Get<T> {
+	/// Return a constant value.
+	fn get() -> T;
+}
+
+impl<T: Default> Get<T> for () {
+	fn get() -> T { T::default() }
+}
+
+/// A trait for querying whether a type can be said to statically "contain" a value. Similar
+/// in nature to `Get`, except it is designed to be lazy rather than active (you can't ask it to
+/// enumerate all values that it contains) and work for multiple values rather than just one.
+pub trait Contains<T> {
+	/// Return `true` if this "contains" the given value `t`.
+	fn contains(t: &T) -> bool;
+}
+
+impl<V: PartialEq, T: Get<V>> Contains<V> for T {
+	fn contains(t: &V) -> bool {
+		&Self::get() == t
+	}
+}
+
+/// The account with the given id was killed.
+#[impl_trait_for_tuples::impl_for_tuples(30)]
+pub trait OnFreeBalanceZero<AccountId> {
+	/// The account was the given id was killed.
+	fn on_free_balance_zero(who: &AccountId);
+}
+
+/// Outcome of a balance update.
+pub enum UpdateBalanceOutcome {
+	/// Account balance was simply updated.
+	Updated,
+	/// The update led to killing the account.
+	AccountKilled,
+}
+
+/// A trait for finding the author of a block header based on the `PreRuntime` digests contained
+/// within it.
+pub trait FindAuthor<Author> {
+	/// Find the author of a block based on the pre-runtime digests.
+	fn find_author<'a, I>(digests: I) -> Option<Author>
+		where I: 'a + IntoIterator<Item=(ConsensusEngineId, &'a [u8])>;
+}
+
+impl<A> FindAuthor<A> for () {
+	fn find_author<'a, I>(_: I) -> Option<A>
+		where I: 'a + IntoIterator<Item=(ConsensusEngineId, &'a [u8])>
+	{
+		None
+	}
+}
+
+/// A trait for verifying the seal of a header and returning the author.
+pub trait VerifySeal<Header, Author> {
+	/// Verify a header and return the author, if any.
+	fn verify_seal(header: &Header) -> Result<Option<Author>, &'static str>;
+}
+
+/// Something which can compute and check proofs of
+/// a historical key owner and return full identification data of that
+/// key owner.
+pub trait KeyOwnerProofSystem<Key> {
+	/// The proof of membership itself.
+	type Proof: Codec;
+	/// The full identification of a key owner and the stash account.
+	type IdentificationTuple: Codec;
+
+	/// Prove membership of a key owner in the current block-state.
+	///
+	/// This should typically only be called off-chain, since it may be
+	/// computationally heavy.
+	///
+	/// Returns `Some` iff the key owner referred to by the given `key` is a
+	/// member of the current set.
+	fn prove(key: Key) -> Option<Self::Proof>;
+
+	/// Check a proof of membership on-chain. Return `Some` iff the proof is
+	/// valid and recent enough to check.
+	fn check_proof(key: Key, proof: Self::Proof) -> Option<Self::IdentificationTuple>;
+}
+
+/// Handler for when some currency "account" decreased in balance for
+/// some reason.
+///
+/// The only reason at present for an increase would be for validator rewards, but
+/// there may be other reasons in the future or for other chains.
+///
+/// Reasons for decreases include:
+///
+/// - Someone got slashed.
+/// - Someone paid for a transaction to be included.
+pub trait OnUnbalanced<Imbalance: TryDrop> {
+	/// Handler for some imbalance. Infallible.
+	fn on_unbalanced(amount: Imbalance) {
+		amount.try_drop().unwrap_or_else(Self::on_nonzero_unbalanced)
+	}
+
+	/// Actually handle a non-zero imbalance. You probably want to implement this rather than
+	/// `on_unbalanced`.
+	fn on_nonzero_unbalanced(amount: Imbalance);
+}
+
+impl<Imbalance: TryDrop> OnUnbalanced<Imbalance> for () {
+	fn on_nonzero_unbalanced(amount: Imbalance) { drop(amount); }
+}
+
+/// Simple boolean for whether an account needs to be kept in existence.
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub enum ExistenceRequirement {
+	/// Operation must not result in the account going out of existence.
+	///
+	/// Note this implies that if the account never existed in the first place, then the operation
+	/// may legitimately leave the account unchanged and still non-existent.
+	KeepAlive,
+	/// Operation may result in account going out of existence.
+	AllowDeath,
+}
+
+/// A type for which some values make sense to be able to drop without further consideration.
+pub trait TryDrop: Sized {
+	/// Drop an instance cleanly. Only works if its value represents "no-operation".
+	fn try_drop(self) -> Result<(), Self>;
+}
+
+/// A trait for a not-quite Linear Type that tracks an imbalance.
+///
+/// Functions that alter account balances return an object of this trait to
+/// express how much account balances have been altered in aggregate. If
+/// dropped, the currency system will take some default steps to deal with
+/// the imbalance (`balances` module simply reduces or increases its
+/// total issuance). Your module should generally handle it in some way,
+/// good practice is to do so in a configurable manner using an
+/// `OnUnbalanced` type for each situation in which your module needs to
+/// handle an imbalance.
+///
+/// Imbalances can either be Positive (funds were added somewhere without
+/// being subtracted elsewhere - e.g. a reward) or Negative (funds deducted
+/// somewhere without an equal and opposite addition - e.g. a slash or
+/// system fee payment).
+///
+/// Since they are unsigned, the actual type is always Positive or Negative.
+/// The trait makes no distinction except to define the `Opposite` type.
+///
+/// New instances of zero value can be created (`zero`) and destroyed
+/// (`drop_zero`).
+///
+/// Existing instances can be `split` and merged either consuming `self` with
+/// `merge` or mutating `self` with `subsume`. If the target is an `Option`,
+/// then `maybe_merge` and `maybe_subsume` might work better. Instances can
+/// also be `offset` with an `Opposite` that is less than or equal to in value.
+///
+/// You can always retrieve the raw balance value using `peek`.
+#[must_use]
+pub trait Imbalance<Balance>: Sized + TryDrop {
+	/// The oppositely imbalanced type. They come in pairs.
+	type Opposite: Imbalance<Balance>;
+
+	/// The zero imbalance. Can be destroyed with `drop_zero`.
+	fn zero() -> Self;
+
+	/// Drop an instance cleanly. Only works if its `self.value()` is zero.
+	fn drop_zero(self) -> Result<(), Self>;
+
+	/// Consume `self` and return two independent instances; the first
+	/// is guaranteed to be at most `amount` and the second will be the remainder.
+	fn split(self, amount: Balance) -> (Self, Self);
+
+	/// Consume `self` and an `other` to return a new instance that combines
+	/// both.
+	fn merge(self, other: Self) -> Self;
+
+	/// Consume `self` and maybe an `other` to return a new instance that combines
+	/// both.
+	fn maybe_merge(self, other: Option<Self>) -> Self {
+		if let Some(o) = other {
+			self.merge(o)
+		} else {
+			self
+		}
+	}
+
+	/// Consume an `other` to mutate `self` into a new instance that combines
+	/// both.
+	fn subsume(&mut self, other: Self);
+
+	/// Maybe consume an `other` to mutate `self` into a new instance that combines
+	/// both.
+	fn maybe_subsume(&mut self, other: Option<Self>) {
+		if let Some(o) = other {
+			self.subsume(o)
+		}
+	}
+
+	/// Consume self and along with an opposite counterpart to return
+	/// a combined result.
+	///
+	/// Returns `Ok` along with a new instance of `Self` if this instance has a
+	/// greater value than the `other`. Otherwise returns `Err` with an instance of
+	/// the `Opposite`. In both cases the value represents the combination of `self`
+	/// and `other`.
+	fn offset(self, other: Self::Opposite) -> Result<Self, Self::Opposite>;
+
+	/// The raw value of self.
+	fn peek(&self) -> Balance;
+}
+
+/// Either a positive or a negative imbalance.
+pub enum SignedImbalance<B, P: Imbalance<B>>{
+	/// A positive imbalance (funds have been created but none destroyed).
+	Positive(P),
+	/// A negative imbalance (funds have been destroyed but none created).
+	Negative(P::Opposite),
+}
+
+impl<
+	P: Imbalance<B, Opposite=N>,
+	N: Imbalance<B, Opposite=P>,
+	B: SimpleArithmetic + FullCodec + Copy + MaybeSerializeDeserialize + Debug + Default,
+> SignedImbalance<B, P> {
+	pub fn zero() -> Self {
+		SignedImbalance::Positive(P::zero())
+	}
+
+	pub fn drop_zero(self) -> Result<(), Self> {
+		match self {
+			SignedImbalance::Positive(x) => x.drop_zero().map_err(SignedImbalance::Positive),
+			SignedImbalance::Negative(x) => x.drop_zero().map_err(SignedImbalance::Negative),
+		}
+	}
+
+	/// Consume `self` and an `other` to return a new instance that combines
+	/// both.
+	pub fn merge(self, other: Self) -> Self {
+		match (self, other) {
+			(SignedImbalance::Positive(one), SignedImbalance::Positive(other)) =>
+				SignedImbalance::Positive(one.merge(other)),
+			(SignedImbalance::Negative(one), SignedImbalance::Negative(other)) =>
+				SignedImbalance::Negative(one.merge(other)),
+			(SignedImbalance::Positive(one), SignedImbalance::Negative(other)) =>
+				if one.peek() > other.peek() {
+					SignedImbalance::Positive(one.offset(other).ok().unwrap_or_else(P::zero))
+				} else {
+					SignedImbalance::Negative(other.offset(one).ok().unwrap_or_else(N::zero))
+				},
+			(one, other) => other.merge(one),
+		}
+	}
+}
+
+/// Split an unbalanced amount two ways between a common divisor.
+pub struct SplitTwoWays<
+	Balance,
+	Imbalance,
+	Part1,
+	Target1,
+	Part2,
+	Target2,
+>(PhantomData<(Balance, Imbalance, Part1, Target1, Part2, Target2)>);
+
+impl<
+	Balance: From<u32> + Saturating + Div<Output=Balance>,
+	I: Imbalance<Balance>,
+	Part1: U32,
+	Target1: OnUnbalanced<I>,
+	Part2: U32,
+	Target2: OnUnbalanced<I>,
+> OnUnbalanced<I> for SplitTwoWays<Balance, I, Part1, Target1, Part2, Target2>
+{
+	fn on_nonzero_unbalanced(amount: I) {
+		let total: u32 = Part1::VALUE + Part2::VALUE;
+		let amount1 = amount.peek().saturating_mul(Part1::VALUE.into()) / total.into();
+		let (imb1, imb2) = amount.split(amount1);
+		Target1::on_unbalanced(imb1);
+		Target2::on_unbalanced(imb2);
+	}
+}
+
+/// Abstraction over a fungible assets system.
+pub trait Currency<AccountId> {
+	/// The balance of an account.
+	type Balance: SimpleArithmetic + FullCodec + Copy + MaybeSerializeDeserialize + Debug + Default;
+
+	/// The opaque token type for an imbalance. This is returned by unbalanced operations
+	/// and must be dealt with. It may be dropped but cannot be cloned.
+	type PositiveImbalance: Imbalance<Self::Balance, Opposite=Self::NegativeImbalance>;
+
+	/// The opaque token type for an imbalance. This is returned by unbalanced operations
+	/// and must be dealt with. It may be dropped but cannot be cloned.
+	type NegativeImbalance: Imbalance<Self::Balance, Opposite=Self::PositiveImbalance>;
+
+	// PUBLIC IMMUTABLES
+
+	/// The combined balance of `who`.
+	fn total_balance(who: &AccountId) -> Self::Balance;
+
+	/// Same result as `slash(who, value)` (but without the side-effects) assuming there are no
+	/// balance changes in the meantime and only the reserved balance is not taken into account.
+	fn can_slash(who: &AccountId, value: Self::Balance) -> bool;
+
+	/// The total amount of issuance in the system.
+	fn total_issuance() -> Self::Balance;
+
+	/// The minimum balance any single account may have. This is equivalent to the `Balances` module's
+	/// `ExistentialDeposit`.
+	fn minimum_balance() -> Self::Balance;
+
+	/// Reduce the total issuance by `amount` and return the according imbalance. The imbalance will
+	/// typically be used to reduce an account by the same amount with e.g. `settle`.
+	///
+	/// This is infallible, but doesn't guarantee that the entire `amount` is burnt, for example
+	/// in the case of underflow.
+	fn burn(amount: Self::Balance) -> Self::PositiveImbalance;
+
+	/// Increase the total issuance by `amount` and return the according imbalance. The imbalance
+	/// will typically be used to increase an account by the same amount with e.g.
+	/// `resolve_into_existing` or `resolve_creating`.
+	///
+	/// This is infallible, but doesn't guarantee that the entire `amount` is issued, for example
+	/// in the case of overflow.
+	fn issue(amount: Self::Balance) -> Self::NegativeImbalance;
+
+	/// The 'free' balance of a given account.
+	///
+	/// This is the only balance that matters in terms of most operations on tokens. It alone
+	/// is used to determine the balance when in the contract execution environment. When this
+	/// balance falls below the value of `ExistentialDeposit`, then the 'current account' is
+	/// deleted: specifically `FreeBalance`. Further, the `OnFreeBalanceZero` callback
+	/// is invoked, giving a chance to external modules to clean up data associated with
+	/// the deleted account.
+	///
+	/// `system::AccountNonce` is also deleted if `ReservedBalance` is also zero (it also gets
+	/// collapsed to zero if it ever becomes less than `ExistentialDeposit`.
+	fn free_balance(who: &AccountId) -> Self::Balance;
+
+	/// Returns `Ok` iff the account is able to make a withdrawal of the given amount
+	/// for the given reason. Basically, it's just a dry-run of `withdraw`.
+	///
+	/// `Err(...)` with the reason why not otherwise.
+	fn ensure_can_withdraw(
+		who: &AccountId,
+		_amount: Self::Balance,
+		reasons: WithdrawReasons,
+		new_balance: Self::Balance,
+	) -> result::Result<(), &'static str>;
+
+	// PUBLIC MUTABLES (DANGEROUS)
+
+	/// Transfer some liquid free balance to another staker.
+	///
+	/// This is a very high-level function. It will ensure all appropriate fees are paid
+	/// and no imbalance in the system remains.
+	fn transfer(
+		source: &AccountId,
+		dest: &AccountId,
+		value: Self::Balance,
+		existence_requirement: ExistenceRequirement,
+	) -> result::Result<(), &'static str>;
+
+	/// Deducts up to `value` from the combined balance of `who`, preferring to deduct from the
+	/// free balance. This function cannot fail.
+	///
+	/// The resulting imbalance is the first item of the tuple returned.
+	///
+	/// As much funds up to `value` will be deducted as possible. If this is less than `value`,
+	/// then a non-zero second item will be returned.
+	fn slash(
+		who: &AccountId,
+		value: Self::Balance
+	) -> (Self::NegativeImbalance, Self::Balance);
+
+	/// Mints `value` to the free balance of `who`.
+	///
+	/// If `who` doesn't exist, nothing is done and an Err returned.
+	fn deposit_into_existing(
+		who: &AccountId,
+		value: Self::Balance
+	) -> result::Result<Self::PositiveImbalance, &'static str>;
+
+	/// Similar to deposit_creating, only accepts a `NegativeImbalance` and returns nothing on
+	/// success.
+	fn resolve_into_existing(
+		who: &AccountId,
+		value: Self::NegativeImbalance,
+	) -> result::Result<(), Self::NegativeImbalance> {
+		let v = value.peek();
+		match Self::deposit_into_existing(who, v) {
+			Ok(opposite) => Ok(drop(value.offset(opposite))),
+			_ => Err(value),
+		}
+	}
+
+	/// Adds up to `value` to the free balance of `who`. If `who` doesn't exist, it is created.
+	///
+	/// Infallible.
+	fn deposit_creating(
+		who: &AccountId,
+		value: Self::Balance,
+	) -> Self::PositiveImbalance;
+
+	/// Similar to deposit_creating, only accepts a `NegativeImbalance` and returns nothing on
+	/// success.
+	fn resolve_creating(
+		who: &AccountId,
+		value: Self::NegativeImbalance,
+	) {
+		let v = value.peek();
+		drop(value.offset(Self::deposit_creating(who, v)));
+	}
+
+	/// Removes some free balance from `who` account for `reason` if possible. If `liveness` is
+	/// `KeepAlive`, then no less than `ExistentialDeposit` must be left remaining.
+	///
+	/// This checks any locks, vesting, and liquidity requirements. If the removal is not possible,
+	/// then it returns `Err`.
+	///
+	/// If the operation is successful, this will return `Ok` with a `NegativeImbalance` whose value
+	/// is `value`.
+	fn withdraw(
+		who: &AccountId,
+		value: Self::Balance,
+		reasons: WithdrawReasons,
+		liveness: ExistenceRequirement,
+	) -> result::Result<Self::NegativeImbalance, &'static str>;
+
+	/// Similar to withdraw, only accepts a `PositiveImbalance` and returns nothing on success.
+	fn settle(
+		who: &AccountId,
+		value: Self::PositiveImbalance,
+		reasons: WithdrawReasons,
+		liveness: ExistenceRequirement,
+	) -> result::Result<(), Self::PositiveImbalance> {
+		let v = value.peek();
+		match Self::withdraw(who, v, reasons, liveness) {
+			Ok(opposite) => Ok(drop(value.offset(opposite))),
+			_ => Err(value),
+		}
+	}
+
+	/// Ensure an account's free balance equals some value; this will create the account
+	/// if needed.
+	///
+	/// Returns a signed imbalance and status to indicate if the account was successfully updated or update
+	/// has led to killing of the account.
+	fn make_free_balance_be(
+		who: &AccountId,
+		balance: Self::Balance,
+	) -> (
+		SignedImbalance<Self::Balance, Self::PositiveImbalance>,
+		UpdateBalanceOutcome,
+	);
+}
+
+/// A currency where funds can be reserved from the user.
+pub trait ReservableCurrency<AccountId>: Currency<AccountId> {
+	/// Same result as `reserve(who, value)` (but without the side-effects) assuming there
+	/// are no balance changes in the meantime.
+	fn can_reserve(who: &AccountId, value: Self::Balance) -> bool;
+
+	/// Deducts up to `value` from reserved balance of `who`. This function cannot fail.
+	///
+	/// As much funds up to `value` will be deducted as possible. If the reserve balance of `who`
+	/// is less than `value`, then a non-zero second item will be returned.
+	fn slash_reserved(
+		who: &AccountId,
+		value: Self::Balance
+	) -> (Self::NegativeImbalance, Self::Balance);
+
+	/// The amount of the balance of a given account that is externally reserved; this can still get
+	/// slashed, but gets slashed last of all.
+	///
+	/// This balance is a 'reserve' balance that other subsystems use in order to set aside tokens
+	/// that are still 'owned' by the account holder, but which are suspendable.
+	///
+	/// When this balance falls below the value of `ExistentialDeposit`, then this 'reserve account'
+	/// is deleted: specifically, `ReservedBalance`.
+	///
+	/// `system::AccountNonce` is also deleted if `FreeBalance` is also zero (it also gets
+	/// collapsed to zero if it ever becomes less than `ExistentialDeposit`.
+	fn reserved_balance(who: &AccountId) -> Self::Balance;
+
+
+	/// Moves `value` from balance to reserved balance.
+	///
+	/// If the free balance is lower than `value`, then no funds will be moved and an `Err` will
+	/// be returned to notify of this. This is different behavior than `unreserve`.
+	fn reserve(who: &AccountId, value: Self::Balance) -> result::Result<(), &'static str>;
+
+	/// Moves up to `value` from reserved balance to free balance. This function cannot fail.
+	///
+	/// As much funds up to `value` will be moved as possible. If the reserve balance of `who`
+	/// is less than `value`, then the remaining amount will be returned.
+	///
+	/// # NOTES
+	///
+	/// - This is different from `reserve`.
+	/// - If the remaining reserved balance is less than `ExistentialDeposit`, it will
+	/// invoke `on_reserved_too_low` and could reap the account.
+	fn unreserve(who: &AccountId, value: Self::Balance) -> Self::Balance;
+
+	/// Moves up to `value` from reserved balance of account `slashed` to free balance of account
+	/// `beneficiary`. `beneficiary` must exist for this to succeed. If it does not, `Err` will be
+	/// returned.
+	///
+	/// As much funds up to `value` will be deducted as possible. If this is less than `value`,
+	/// then `Ok(non_zero)` will be returned.
+	fn repatriate_reserved(
+		slashed: &AccountId,
+		beneficiary: &AccountId,
+		value: Self::Balance
+	) -> result::Result<Self::Balance, &'static str>;
+}
+
+/// An identifier for a lock. Used for disambiguating different locks so that
+/// they can be individually replaced or removed.
+pub type LockIdentifier = [u8; 8];
+
+/// A currency whose accounts can have liquidity restrictions.
+pub trait LockableCurrency<AccountId>: Currency<AccountId> {
+	/// The quantity used to denote time; usually just a `BlockNumber`.
+	type Moment;
+
+	/// Create a new balance lock on account `who`.
+	///
+	/// If the new lock is valid (i.e. not already expired), it will push the struct to
+	/// the `Locks` vec in storage. Note that you can lock more funds than a user has.
+	///
+	/// If the lock `id` already exists, this will update it.
+	fn set_lock(
+		id: LockIdentifier,
+		who: &AccountId,
+		amount: Self::Balance,
+		until: Self::Moment,
+		reasons: WithdrawReasons,
+	);
+
+	/// Changes a balance lock (selected by `id`) so that it becomes less liquid in all
+	/// parameters or creates a new one if it does not exist.
+	///
+	/// Calling `extend_lock` on an existing lock `id` differs from `set_lock` in that it
+	/// applies the most severe constraints of the two, while `set_lock` replaces the lock
+	/// with the new parameters. As in, `extend_lock` will set:
+	/// - maximum `amount`
+	/// - farthest duration (`until`)
+	/// - bitwise mask of all `reasons`
+	fn extend_lock(
+		id: LockIdentifier,
+		who: &AccountId,
+		amount: Self::Balance,
+		until: Self::Moment,
+		reasons: WithdrawReasons,
+	);
+
+	/// Remove an existing lock.
+	fn remove_lock(
+		id: LockIdentifier,
+		who: &AccountId,
+	);
+}
+
+bitmask! {
+	/// Reasons for moving funds out of an account.
+	#[derive(Encode, Decode)]
+	pub mask WithdrawReasons: i8 where
+
+	/// Reason for moving funds out of an account.
+	#[derive(Encode, Decode)]
+	flags WithdrawReason {
+		/// In order to pay for (system) transaction costs.
+		TransactionPayment = 0b00000001,
+		/// In order to transfer ownership.
+		Transfer = 0b00000010,
+		/// In order to reserve some funds for a later return or repatriation
+		Reserve = 0b00000100,
+		/// In order to pay some other (higher-level) fees.
+		Fee = 0b00001000,
+		/// In order to tip a validator for transaction inclusion.
+		Tip = 0b00010000,
+	}
+}
+
+pub trait Time {
+	type Moment: SimpleArithmetic + FullCodec + Clone + Default + Copy;
+
+	fn now() -> Self::Moment;
+}
+
+impl WithdrawReasons {
+	/// Choose all variants except for `one`.
+	///
+	/// ```rust
+	/// # use palette_support::traits::{WithdrawReason, WithdrawReasons};
+	/// # fn main() {
+	/// assert_eq!(
+	/// 	WithdrawReason::Fee | WithdrawReason::Transfer | WithdrawReason::Reserve | WithdrawReason::Tip,
+	/// 	WithdrawReasons::except(WithdrawReason::TransactionPayment),
+	///	);
+	/// # }
+	/// ```
+	pub fn except(one: WithdrawReason) -> WithdrawReasons {
+		let mut mask = Self::all();
+		mask.toggle(one);
+		mask
+	}
+}
+
+/// Trait for type that can handle incremental changes to a set of account IDs.
+pub trait ChangeMembers<AccountId: Clone + Ord> {
+	/// A number of members `incoming` just joined the set and replaced some `outgoing` ones. The
+	/// new set is given by `new`, and need not be sorted.
+	fn change_members(incoming: &[AccountId], outgoing: &[AccountId], mut new: Vec<AccountId>) {
+		new.sort_unstable();
+		Self::change_members_sorted(incoming, outgoing, &new[..]);
+	}
+
+	/// A number of members `_incoming` just joined the set and replaced some `_outgoing` ones. The
+	/// new set is thus given by `sorted_new` and **must be sorted**.
+	///
+	/// NOTE: This is the only function that needs to be implemented in `ChangeMembers`.
+	fn change_members_sorted(
+		incoming: &[AccountId],
+		outgoing: &[AccountId],
+		sorted_new: &[AccountId],
+	);
+
+	/// Set the new members; they **must already be sorted**. This will compute the diff and use it to
+	/// call `change_members_sorted`.
+	fn set_members_sorted(new_members: &[AccountId], old_members: &[AccountId]) {
+		let (incoming, outgoing) = Self::compute_members_diff(new_members, old_members);
+		Self::change_members_sorted(&incoming[..], &outgoing[..], &new_members);
+	}
+
+	/// Set the new members; they **must already be sorted**. This will compute the diff and use it to
+	/// call `change_members_sorted`.
+	fn compute_members_diff(
+		new_members: &[AccountId],
+		old_members: &[AccountId]
+	) -> (Vec<AccountId>, Vec<AccountId>) {
+		let mut old_iter = old_members.iter();
+		let mut new_iter = new_members.iter();
+		let mut incoming = Vec::new();
+		let mut outgoing = Vec::new();
+		let mut old_i = old_iter.next();
+		let mut new_i = new_iter.next();
+		loop {
+			match (old_i, new_i) {
+				(None, None) => break,
+				(Some(old), Some(new)) if old == new => {
+					old_i = old_iter.next();
+					new_i = new_iter.next();
+				}
+				(Some(old), Some(new)) if old < new => {
+					outgoing.push(old.clone());
+					old_i = old_iter.next();
+				}
+				(Some(old), None) => {
+					outgoing.push(old.clone());
+					old_i = old_iter.next();
+				}
+				(_, Some(new)) => {
+					incoming.push(new.clone());
+					new_i = new_iter.next();
+				}
+			}
+		}
+		(incoming, outgoing)
+	}
+}
+
+impl<T: Clone + Ord> ChangeMembers<T> for () {
+	fn change_members(_: &[T], _: &[T], _: Vec<T>) {}
+	fn change_members_sorted(_: &[T], _: &[T], _: &[T]) {}
+	fn set_members_sorted(_: &[T], _: &[T]) {}
+}
+
+/// Trait for type that can handle the initialization of account IDs at genesis.
+pub trait InitializeMembers<AccountId> {
+	/// Initialize the members to the given `members`.
+	fn initialize_members(members: &[AccountId]);
+}
+
+impl<T> InitializeMembers<T> for () {
+	fn initialize_members(_: &[T]) {}
+}
+
+// A trait that is able to provide randomness.
+pub trait Randomness<Output> {
+	/// Get a "random" value
+	///
+	/// Being a deterministic blockchain, real randomness is difficult to come by. This gives you
+	/// something that approximates it. `subject` is a context identifier and allows you to get a
+	/// different result to other callers of this function; use it like
+	/// `random(&b"my context"[..])`.
+	fn random(subject: &[u8]) -> Output;
+
+	/// Get the basic random seed.
+	///
+	/// In general you won't want to use this, but rather `Self::random` which allows you to give a
+	/// subject for the random result and whose value will be independently low-influence random
+	/// from any other such seeds.
+	fn random_seed() -> Output {
+		Self::random(&[][..])
+	}
+}

substrate/palette/support/src/unsigned.rs

@@ -0,0 +1,166 @@
+// Copyright 2019 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+#[doc(hidden)]
+#[allow(deprecated)]
+pub use crate::sr_primitives::traits::ValidateUnsigned;
+#[doc(hidden)]
+pub use crate::sr_primitives::transaction_validity::{TransactionValidity, UnknownTransaction};
+#[doc(hidden)]
+pub use crate::sr_primitives::ApplyError;
+
+
+/// Implement `ValidateUnsigned` for `Runtime`.
+/// All given modules need to implement `ValidateUnsigned`.
+///
+/// # Example
+///
+/// ```
+/// # mod timestamp {
+/// # 	pub struct Module;
+/// #
+/// # 	impl palette_support::unsigned::ValidateUnsigned for Module {
+/// # 		type Call = Call;
+/// #
+/// # 		fn validate_unsigned(call: &Self::Call) -> palette_support::unsigned::TransactionValidity {
+/// # 			unimplemented!();
+/// # 		}
+/// # 	}
+/// #
+/// # 	pub enum Call {
+/// # 	}
+/// # }
+/// #
+/// # pub type Timestamp = timestamp::Module;
+/// #
+/// #
+/// # pub enum Call {
+/// # 	Timestamp(timestamp::Call),
+/// # }
+/// # #[allow(unused)]
+/// pub struct Runtime;
+///
+/// palette_support::impl_outer_validate_unsigned! {
+/// 	impl ValidateUnsigned for Runtime {
+/// 		Timestamp
+/// 	}
+/// }
+/// ```
+#[macro_export]
+macro_rules! impl_outer_validate_unsigned {
+	(
+		impl ValidateUnsigned for $runtime:ident {
+			$( $module:ident )*
+		}
+	) => {
+		#[allow(deprecated)] // Allow ValidateUnsigned
+		impl $crate::unsigned::ValidateUnsigned for $runtime {
+			type Call = Call;
+
+			fn pre_dispatch(call: &Self::Call) -> Result<(), $crate::unsigned::ApplyError> {
+				#[allow(unreachable_patterns)]
+				match call {
+					$( Call::$module(inner_call) => $module::pre_dispatch(inner_call), )*
+					// pre-dispatch should not stop inherent extrinsics, validation should prevent
+					// including arbitrary (non-inherent) extrinsics to blocks.
+					_ => Ok(()),
+				}
+			}
+
+			fn validate_unsigned(call: &Self::Call) -> $crate::unsigned::TransactionValidity {
+				#[allow(unreachable_patterns)]
+				match call {
+					$( Call::$module(inner_call) => $module::validate_unsigned(inner_call), )*
+					_ => $crate::unsigned::UnknownTransaction::NoUnsignedValidator.into(),
+				}
+			}
+		}
+	};
+}
+
+#[cfg(test)]
+mod test_empty_call {
+	pub enum Call {}
+
+	#[allow(unused)]
+	pub struct Runtime;
+
+	impl_outer_validate_unsigned! {
+		impl ValidateUnsigned for Runtime {
+		}
+	}
+}
+
+#[cfg(test)]
+mod test_partial_and_full_call {
+	pub mod timestamp {
+		pub struct Module;
+
+		#[allow(deprecated)] // Allow ValidateUnsigned
+		impl super::super::ValidateUnsigned for Module {
+			type Call = Call;
+
+			fn validate_unsigned(_call: &Self::Call) -> super::super::TransactionValidity {
+				unimplemented!();
+			}
+		}
+
+		pub enum Call {
+			Foo,
+		}
+	}
+
+	mod test_full_unsigned {
+		pub type Timestamp = super::timestamp::Module;
+
+		pub enum Call {
+			Timestamp(super::timestamp::Call),
+		}
+
+		pub struct Runtime;
+
+		impl_outer_validate_unsigned! {
+			impl ValidateUnsigned for Runtime {
+				Timestamp
+			}
+		}
+
+		#[test]
+		fn used() {
+			let _ = Call::Timestamp(super::timestamp::Call::Foo);
+			let _ = Runtime;
+		}
+	}
+
+	mod test_not_full_unsigned {
+		pub enum Call {
+			Timestamp(super::timestamp::Call),
+		}
+
+		pub struct Runtime;
+
+		impl_outer_validate_unsigned! {
+			impl ValidateUnsigned for Runtime {
+			}
+		}
+
+		#[test]
+		fn used() {
+			let _ = Call::Timestamp(super::timestamp::Call::Foo);
+			let _ = Runtime;
+		}
+	}
+}