sp_runtime_interface_proc_macro/runtime_interface/
trait_decl_impl.rs

1// This file is part of Substrate.
2
3// Copyright (C) Parity Technologies (UK) Ltd.
4// SPDX-License-Identifier: Apache-2.0
5
6// Licensed under the Apache License, Version 2.0 (the "License");
7// you may not use this file except in compliance with the License.
8// You may obtain a copy of the License at
9//
10// 	http://www.apache.org/licenses/LICENSE-2.0
11//
12// Unless required by applicable law or agreed to in writing, software
13// distributed under the License is distributed on an "AS IS" BASIS,
14// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15// See the License for the specific language governing permissions and
16// limitations under the License.
17
18//! Checks the trait declaration, makes the trait declaration module local, removes all method
19//! default implementations and implements the trait for `&mut dyn Externalities`.
20
21use crate::utils::{
22	create_function_ident_with_version, generate_crate_access, get_function_argument_types,
23	get_runtime_interface,
24};
25
26use syn::{
27	fold::{self, Fold},
28	spanned::Spanned,
29	Error, Generics, ItemTrait, Receiver, Result, TraitItemFn, Type, Visibility,
30};
31
32use proc_macro2::TokenStream;
33
34use quote::quote;
35
36/// Process the given trait definition, by checking that the definition is valid, fold it to the
37/// essential definition and implement this essential definition for `dyn Externalities`.
38pub fn process(trait_def: &ItemTrait, is_wasm_only: bool) -> Result<TokenStream> {
39	let impl_trait = impl_trait_for_externalities(trait_def, is_wasm_only)?;
40	let essential_trait_def = declare_essential_trait(trait_def)?;
41
42	Ok(quote! {
43		#impl_trait
44
45		#essential_trait_def
46	})
47}
48
49/// Converts the given trait definition into the essential trait definition without method
50/// default implementations and visibility set to inherited.
51struct ToEssentialTraitDef {
52	/// All errors found while doing the conversion.
53	errors: Vec<Error>,
54	methods: Vec<TraitItemFn>,
55}
56
57impl ToEssentialTraitDef {
58	fn new() -> Self {
59		ToEssentialTraitDef { errors: vec![], methods: vec![] }
60	}
61
62	fn into_methods(self) -> Result<Vec<TraitItemFn>> {
63		let mut errors = self.errors;
64		let methods = self.methods;
65		if let Some(first_error) = errors.pop() {
66			Err(errors.into_iter().fold(first_error, |mut o, n| {
67				o.combine(n);
68				o
69			}))
70		} else {
71			Ok(methods)
72		}
73	}
74
75	fn process(&mut self, method: &TraitItemFn, version: u32) {
76		let mut folded = self.fold_trait_item_fn(method.clone());
77		folded.sig.ident = create_function_ident_with_version(&folded.sig.ident, version);
78		crate::utils::unpack_inner_types_in_signature(&mut folded.sig);
79		self.methods.push(folded);
80	}
81
82	fn push_error<S: Spanned>(&mut self, span: &S, msg: &str) {
83		self.errors.push(Error::new(span.span(), msg));
84	}
85
86	fn error_on_generic_parameters(&mut self, generics: &Generics) {
87		if let Some(param) = generics.params.first() {
88			self.push_error(param, "Generic parameters not supported.");
89		}
90	}
91}
92
93impl Fold for ToEssentialTraitDef {
94	fn fold_trait_item_fn(&mut self, mut method: TraitItemFn) -> TraitItemFn {
95		if method.default.take().is_none() {
96			self.push_error(&method, "Methods need to have an implementation.");
97		}
98
99		let arg_types = get_function_argument_types(&method.sig);
100		arg_types
101			.filter_map(|ty| match *ty {
102				Type::ImplTrait(impl_trait) => Some(impl_trait),
103				_ => None,
104			})
105			.for_each(|invalid| self.push_error(&invalid, "`impl Trait` syntax not supported."));
106
107		self.error_on_generic_parameters(&method.sig.generics);
108
109		method.attrs.retain(|a| !a.path().is_ident("version"));
110
111		fold::fold_trait_item_fn(self, method)
112	}
113
114	fn fold_item_trait(&mut self, mut trait_def: ItemTrait) -> ItemTrait {
115		self.error_on_generic_parameters(&trait_def.generics);
116
117		trait_def.vis = Visibility::Inherited;
118		fold::fold_item_trait(self, trait_def)
119	}
120
121	fn fold_receiver(&mut self, receiver: Receiver) -> Receiver {
122		if receiver.reference.is_none() {
123			self.push_error(&receiver, "Taking `Self` by value is not allowed.");
124		}
125
126		fold::fold_receiver(self, receiver)
127	}
128}
129
130fn declare_essential_trait(trait_def: &ItemTrait) -> Result<TokenStream> {
131	let trait_ = &trait_def.ident;
132
133	if let Some(param) = trait_def.generics.params.first() {
134		return Err(Error::new(param.span(), "Generic parameters not supported."))
135	}
136
137	let interface = get_runtime_interface(trait_def)?;
138	let mut folder = ToEssentialTraitDef::new();
139	for (version, interface_method) in interface.all_versions() {
140		folder.process(interface_method, version);
141	}
142	let methods = folder.into_methods()?;
143
144	Ok(quote! {
145		trait #trait_ {
146			#( #methods )*
147		}
148	})
149}
150
151/// Implements the given trait definition for `dyn Externalities`.
152fn impl_trait_for_externalities(trait_def: &ItemTrait, is_wasm_only: bool) -> Result<TokenStream> {
153	let trait_ = &trait_def.ident;
154	let crate_ = generate_crate_access();
155	let interface = get_runtime_interface(trait_def)?;
156	let methods = interface.all_versions().map(|(version, method)| {
157		let mut cloned = (*method).clone();
158		cloned.attrs.retain(|a| !a.path().is_ident("version"));
159		cloned.sig.ident = create_function_ident_with_version(&cloned.sig.ident, version);
160		crate::utils::unpack_inner_types_in_signature(&mut cloned.sig);
161		cloned
162	});
163
164	let impl_type = if is_wasm_only {
165		quote!( &mut dyn #crate_::sp_wasm_interface::FunctionContext )
166	} else {
167		quote!( &mut dyn #crate_::Externalities )
168	};
169
170	Ok(quote! {
171		#[cfg(not(substrate_runtime))]
172		impl #trait_ for #impl_type {
173			#( #methods )*
174		}
175	})
176}
sp_runtime_interface_proc_macro/runtime_interface/trait_decl_impl.rs

sp_runtime_interface_proc_macro/runtime_interface/
trait_decl_impl.rs
