1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139

// This file is part of Substrate.

// Copyright (C) 2017-2021 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// 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.

//! Implementation of the trait instance and the instance structures implementing it.
//! (For not instantiable traits there is still the inherent instance implemented).

use super::DeclStorageDefExt;
use crate::NUMBER_OF_INSTANCE;
use proc_macro2::{Span, TokenStream};
use quote::quote;

pub(crate) const INHERENT_INSTANCE_NAME: &str = "__InherentHiddenInstance";

// Used to generate an instance implementation.
struct InstanceDef {
	prefix: String,
	instance_struct: syn::Ident,
	doc: TokenStream,
	// Index is same as instance number. Default is 0.
	index: u8,
}

pub fn decl_and_impl(def: &DeclStorageDefExt) -> TokenStream {
	let scrate = &def.hidden_crate;
	let mut impls = TokenStream::new();

	impls.extend(reexport_instance_trait(scrate, def));

	// Implementation of instances.
	if let Some(module_instance) = &def.module_instance {
		let instance_defs = (1..=NUMBER_OF_INSTANCE)
			.map(|i| {
				let name = format!("Instance{}", i);
				InstanceDef {
					instance_struct: syn::Ident::new(&name, proc_macro2::Span::call_site()),
					prefix: name,
					doc: quote!(#[doc=r"Module instance"]),
					index: i,
				}
			})
			.chain(module_instance.instance_default.as_ref().map(|ident| InstanceDef {
				prefix: String::new(),
				instance_struct: ident.clone(),
				doc: quote!(#[doc=r"Default module instance"]),
				index: 0,
			}));

		for instance_def in instance_defs {
			impls.extend(create_and_impl_instance_struct(scrate, &instance_def, def));
		}
	}

	// The name of the inherently available instance.
	let inherent_instance = syn::Ident::new(INHERENT_INSTANCE_NAME, Span::call_site());

	// Implementation of inherent instance.
	if let Some(default_instance) =
		def.module_instance.as_ref().and_then(|i| i.instance_default.as_ref())
	{
		impls.extend(quote! {
			/// Hidden instance generated to be internally used when module is used without
			/// instance.
			#[doc(hidden)]
			pub type #inherent_instance = #default_instance;
		});
	} else {
		let instance_def = InstanceDef {
			prefix: String::new(),
			instance_struct: inherent_instance,
			doc: quote!(
				/// Hidden instance generated to be internally used when module is used without
				/// instance.
				#[doc(hidden)]
			),
			// This is just to make the type system happy. Not actually used.
			index: 0,
		};
		impls.extend(create_and_impl_instance_struct(scrate, &instance_def, def));
	}

	impls
}

fn reexport_instance_trait(scrate: &TokenStream, def: &DeclStorageDefExt) -> TokenStream {
	if let Some(i) = def.module_instance.as_ref() {
		let instance_trait = &i.instance_trait;
		quote!(
			/// Local import of frame_support::traits::Instance
			// This import is not strictly needed but made in order not to have breaking change.
			use #scrate::traits::Instance as #instance_trait;
		)
	} else {
		quote!()
	}
}

fn create_and_impl_instance_struct(
	scrate: &TokenStream,
	instance_def: &InstanceDef,
	def: &DeclStorageDefExt,
) -> TokenStream {
	let instance_trait = quote!( #scrate::traits::Instance );

	let instance_struct = &instance_def.instance_struct;
	let prefix = format!("{}{}", instance_def.prefix, def.crate_name.to_string());
	let doc = &instance_def.doc;
	let index = instance_def.index;

	quote! {
		// Those trait are derived because of wrong bounds for generics
		#[derive(
			Clone, Eq, PartialEq,
			#scrate::codec::Encode,
			#scrate::codec::Decode,
			#scrate::scale_info::TypeInfo,
			#scrate::RuntimeDebug,
		)]
		#doc
		pub struct #instance_struct;
		impl #instance_trait for #instance_struct {
			const PREFIX: &'static str = #prefix;
			const INDEX: u8 = #index;
		}
	}
}