pallet_assets/
impl_stored_map.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//! Assets pallet's `StoredMap` implementation.
19
20use super::*;
21
22impl<T: Config<I>, I: 'static> StoredMap<(T::AssetId, T::AccountId), T::Extra> for Pallet<T, I> {
23	fn get(id_who: &(T::AssetId, T::AccountId)) -> T::Extra {
24		let (id, who) = id_who;
25		Account::<T, I>::get(id, who).map(|a| a.extra).unwrap_or_default()
26	}
27
28	fn try_mutate_exists<R, E: From<DispatchError>>(
29		id_who: &(T::AssetId, T::AccountId),
30		f: impl FnOnce(&mut Option<T::Extra>) -> Result<R, E>,
31	) -> Result<R, E> {
32		let (id, who) = id_who;
33		let mut maybe_extra = Account::<T, I>::get(id, who).map(|a| a.extra);
34		let r = f(&mut maybe_extra)?;
35		// They want to write some value or delete it.
36		// If the account existed and they want to write a value, then we write.
37		// If the account didn't exist and they want to delete it, then we let it pass.
38		// Otherwise, we fail.
39		Account::<T, I>::try_mutate(id, who, |maybe_account| {
40			if let Some(extra) = maybe_extra {
41				// They want to write a value. Let this happen only if the account actually exists.
42				if let Some(ref mut account) = maybe_account {
43					account.extra = extra;
44				} else {
45					return Err(DispatchError::NoProviders.into())
46				}
47			} else {
48				// They want to delete it. Let this pass if the item never existed anyway.
49				ensure!(maybe_account.is_none(), DispatchError::ConsumerRemaining);
50			}
51			Ok(r)
52		})
53	}
54}
pallet_assets/impl_stored_map.rs

pallet_assets/
impl_stored_map.rs
