scale-info 0.4.1

Info about SCALE encodable Rust types
Documentation 
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// Copyright 2019-2020 Parity Technologies (UK) Ltd.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#![cfg_attr(not(feature = "std"), no_std)]
#![deny(missing_docs)]

//! Efficient and compact serialization of Rust types.
//!
//! This library provides structures to easily retrieve compile-time type
//! information at runtime and also to serialize this information in a compact
//! form.
//!
//! # Registry
//!
//! At the heart of its functionality is the [`Registry`](`crate::Registry`) that acts as cache for
//! known types in order to efficiently deduplicate them and thus compactify the overall
//! serialization.
//!
//! # Type Information
//!
//! Information about types is provided via the [`TypeInfo`](`crate::TypeInfo`) trait.
//!
//! This trait should be implemented for all types that are serializable.
//! For this the library provides implementations for all commonly used Rust
//! standard types and provides derive macros for simpler implementation of user
//! provided custom types.
//!
//! # Compaction Forms
//!
//! There is an uncompact form, called [`MetaForm`](`crate::form::MetaForm`) that acts as a bridge
//! from compile-time type information at runtime in order to easily retrieve all information needed
//! to uniquely identify types.
//!
//! The compact form is retrieved by the [`IntoCompact`](`crate::IntoCompact`) trait and internally
//! used by the [`Registry`](`crate::Registry`) in order to convert the uncompact types
//! into their compact form.
//!
//! # Symbols and Namespaces
//!
//! To differentiate two types sharing the same name namespaces are used.
//! Commonly the namespace is equal to the one where the type has been defined in. For Rust prelude
//! types such as [`Option`](`std::option::Option`) and [`Result`](`std::result::Result`) the root
//! namespace (empty namespace) is used.
//!
//! To use this library simply use the [`MetaForm`](`crate::form::MetaForm`) initially with your own data
//! structures and at best make them generic over the [`Form`](`crate::form::Form`) trait just as has
//! been done in this crate with [`TypeInfo`](`crate::TypeInfo`) in order to go for a simple
//! implementation of [`IntoCompact`](`crate::IntoCompact`). Use a single instance of the [`Registry`](`crate::Registry`) for
//! compaction and provide this registry instance upon serialization. Done.
//!
//! A usage example can be found in ink! here:
//! https://github.com/paritytech/ink/blob/master/abi/src/specs.rs

#[cfg(not(feature = "std"))]
extern crate alloc;

/// Takes a number of types and returns a vector that contains their respective
/// [`MetaType`](`crate::MetaType`) instances.
///
/// This is useful for places that require inputs of iterators over [`MetaType`](`crate::MetaType`)
/// instances and provide a way out of code bloat in these scenarious.
///
/// # Example
///
/// ```
/// # use scale_info::tuple_meta_type;
/// assert_eq!(
///     tuple_meta_type!(i32, [u8; 32], String),
///     {
///         use scale_info::MetaType;
///         let mut vec = Vec::new();
///         vec.push(MetaType::new::<i32>());
///         vec.push(MetaType::new::<[u8; 32]>());
///         vec.push(MetaType::new::<String>());
///         vec
///     }
/// );
/// ```
#[macro_export]
macro_rules! tuple_meta_type {
	( $($ty:ty),* ) => {
		{
			#[cfg(not(feature = "std"))]
			extern crate alloc as _alloc;
			#[cfg(not(feature = "std"))]
			#[allow(unused_mut)]
			let mut v = _alloc::vec![];

			#[cfg(feature = "std")]
			#[allow(unused_mut)]
			let mut v = std::vec![];

			$(
				v.push($crate::MetaType::new::<$ty>());
			)*
			v
		}
	}
}

mod tm_std;

pub mod build;
pub mod form;
mod impls;
pub mod interner;
mod meta_type;
mod registry;
mod ty;
mod utils;

#[cfg(test)]
mod tests;

pub use self::{
	meta_type::MetaType,
	registry::{IntoCompact, Registry, RegistryReadOnly},
	ty::*,
};

#[cfg(feature = "derive")]
pub use scale_info_derive::TypeInfo;

/// Implementors return their meta type information.
pub trait TypeInfo {
	/// Returns the static type identifier for `Self`.
	fn type_info() -> Type;
}

/// Returns the runtime bridge to the types compile-time type information.
pub fn meta_type<T>() -> MetaType
where
	T: ?Sized + TypeInfo + 'static,
{
	MetaType::new::<T>()
}