Rename Palette to FRAME (#4182)

* palette -> frame

* PALETTE, Palette -> FRAME

* Move folder pallete -> frame

* Update docs/Structure.adoc

Co-Authored-By: Benjamin Kampmann <ben.kampmann@googlemail.com>

* Update docs/README.adoc

Co-Authored-By: Benjamin Kampmann <ben.kampmann@googlemail.com>

* Update README.adoc

substrate/frame/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 frame_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 frame_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 )*
+		}
+	}
+}