decl_storage as a proc_macro (#1176)

* `decl_storage` parsing of the macro (TODO change tool crate structure)

* Start formatting, for now use inner macro.
Still missing optional formating last part (genesis ...).

* Calling extra genesis macro

* decl_storage lines parsing.

* genesis macro as quote (need some cleaning reorg)

* dirty $crate substitute

* proc crate reorg.

* PR impl : skip usage of phantom data, it only applies in test and
council (others required it).

* Remaining macro of decl_storage, warning stringify behave sometime
oddly.

* Formatting code and some cleaning.

* Include line parsing to main struct (cannot use existing macro anymore).

* Remove genesis phantom data when there is already a field with type
parameter.

* Revert wasm files

* Remove old version of `decl_storage`.

* Fix false positive for phantom trait (additional type check on config
build).

* slight changes:
- return token errors instead of panic
- do not use useless intermediate vec

* Update srml/support/procedural/tools/derive/src/lib.rs

remove indent

Co-Authored-By: cheme <emericchevalier.pro@gmail.com>

* Switch iterations to fold, remove unused import.

substrate/srml/support/procedural/tools/src/lib.rs

@@ -0,0 +1,94 @@
+// Copyright 2017-2018 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/>.
+
+// tag::description[]
+//! Proc macro helpers for procedural macros
+// end::description[]
+
+extern crate syn;
+#[macro_use]
+extern crate quote;
+extern crate proc_macro2;
+
+extern crate proc_macro;
+
+#[macro_use] extern crate srml_support_procedural_tools_derive;
+
+// reexport proc macros
+pub use srml_support_procedural_tools_derive::*;
+
+pub mod syn_ext;
+
+#[macro_export]
+macro_rules! custom_keyword_impl {
+	($name:ident, $keyident:expr, $keydisp:expr) => {
+
+		impl CustomKeyword for $name {
+			fn ident() -> &'static str { $keyident }
+			fn display() -> &'static str { $keydisp }
+		}
+
+	}
+}
+
+#[macro_export]
+macro_rules! custom_keyword {
+	($name:ident, $keyident:expr, $keydisp:expr) => {
+
+		#[derive(Debug)]
+		struct $name;
+
+		custom_keyword_impl!($name, $keyident, $keydisp);
+
+	}
+}
+
+
+// TODO following functions are copied from sr-api-macros : do a merge to get a unique procedural
+// macro tooling crate (this crate path does not look good for it)
+
+use proc_macro2::{TokenStream, Span};
+use syn::Ident;
+
+fn generate_hidden_includes_mod_name(unique_id: &str) -> Ident {
+	Ident::new(&format!("sr_api_hidden_includes_{}", unique_id), Span::call_site())
+}
+
+/// Generates the access to the `subtrate_client` crate.
+pub fn generate_crate_access(unique_id: &str, def_crate: &str) -> TokenStream {
+	if ::std::env::var("CARGO_PKG_NAME").unwrap() == def_crate {
+		quote!( crate )
+	} else {
+		let mod_name = generate_hidden_includes_mod_name(unique_id);
+		quote!( self::#mod_name::hidden_include )
+	}.into()
+}
+
+/// Generates the hidden includes that are required to make the macro independent from its scope.
+pub fn generate_hidden_includes(unique_id: &str, def_crate: &str, crate_id: &str) -> TokenStream {
+	let crate_id = Ident::new(crate_id, Span::call_site());
+	if ::std::env::var("CARGO_PKG_NAME").unwrap() == def_crate {
+		TokenStream::new()
+	} else {
+		let mod_name = generate_hidden_includes_mod_name(unique_id);
+		quote!(
+			#[doc(hidden)]
+			mod #mod_name {
+				pub extern crate #crate_id as hidden_include;
+			}
+		)
+	}.into()
+}