frame_support/traits/tokens/currency/
lockable.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//! The lockable currency trait and some associated types.
19
20use super::{super::misc::WithdrawReasons, Currency};
21use crate::{dispatch::DispatchResult, traits::misc::Get};
22
23/// An identifier for a lock. Used for disambiguating different locks so that
24/// they can be individually replaced or removed.
25pub type LockIdentifier = [u8; 8];
26
27/// A currency whose accounts can have liquidity restrictions.
28///
29/// Note: Consider using [`crate::traits::fungible::MutateFreeze`] (and family) as it returns a
30/// `Result`, and is therefore much safer to use.
31pub trait LockableCurrency<AccountId>: Currency<AccountId> {
32	/// The quantity used to denote time; usually just a `BlockNumber`.
33	type Moment;
34
35	/// The maximum number of locks a user should have on their account.
36	type MaxLocks: Get<u32>;
37
38	/// Create a new balance lock on account `who`.
39	///
40	/// If the new lock is valid (i.e. not already expired), it will push the struct to
41	/// the `Locks` vec in storage. Note that you can lock more funds than a user has.
42	///
43	/// If the lock `id` already exists, this will update it.
44	fn set_lock(
45		id: LockIdentifier,
46		who: &AccountId,
47		amount: Self::Balance,
48		reasons: WithdrawReasons,
49	);
50
51	/// Changes a balance lock (selected by `id`) so that it becomes less liquid in all
52	/// parameters or creates a new one if it does not exist.
53	///
54	/// Calling `extend_lock` on an existing lock `id` differs from `set_lock` in that it
55	/// applies the most severe constraints of the two, while `set_lock` replaces the lock
56	/// with the new parameters. As in, `extend_lock` will set:
57	/// - maximum `amount`
58	/// - bitwise mask of all `reasons`
59	fn extend_lock(
60		id: LockIdentifier,
61		who: &AccountId,
62		amount: Self::Balance,
63		reasons: WithdrawReasons,
64	);
65
66	/// Remove an existing lock.
67	fn remove_lock(id: LockIdentifier, who: &AccountId);
68}
69
70/// A inspect interface for a currency whose accounts can have liquidity restrictions.
71pub trait InspectLockableCurrency<AccountId>: LockableCurrency<AccountId> {
72	/// Amount of funds locked for `who` associated with `id`.
73	fn balance_locked(id: LockIdentifier, who: &AccountId) -> Self::Balance;
74}
75
76/// A vesting schedule over a currency. This allows a particular currency to have vesting limits
77/// applied to it.
78pub trait VestingSchedule<AccountId> {
79	/// The quantity used to denote time; usually just a `BlockNumber`.
80	type Moment;
81
82	/// The currency that this schedule applies to.
83	type Currency: Currency<AccountId>;
84
85	/// Get the amount that is currently being vested and cannot be transferred out of this account.
86	/// Returns `None` if the account has no vesting schedule.
87	fn vesting_balance(who: &AccountId)
88		-> Option<<Self::Currency as Currency<AccountId>>::Balance>;
89
90	/// Adds a vesting schedule to a given account.
91	///
92	/// If the account has `MaxVestingSchedules`, an Error is returned and nothing
93	/// is updated.
94	///
95	/// Is a no-op if the amount to be vested is zero.
96	///
97	/// NOTE: This doesn't alter the free balance of the account.
98	fn add_vesting_schedule(
99		who: &AccountId,
100		locked: <Self::Currency as Currency<AccountId>>::Balance,
101		per_block: <Self::Currency as Currency<AccountId>>::Balance,
102		starting_block: Self::Moment,
103	) -> DispatchResult;
104
105	/// Checks if `add_vesting_schedule` would work against `who`.
106	fn can_add_vesting_schedule(
107		who: &AccountId,
108		locked: <Self::Currency as Currency<AccountId>>::Balance,
109		per_block: <Self::Currency as Currency<AccountId>>::Balance,
110		starting_block: Self::Moment,
111	) -> DispatchResult;
112
113	/// Remove a vesting schedule for a given account.
114	///
115	/// NOTE: This doesn't alter the free balance of the account.
116	fn remove_vesting_schedule(who: &AccountId, schedule_index: u32) -> DispatchResult;
117}
118
119/// A vested transfer over a currency. This allows a transferred amount to vest over time.
120pub trait VestedTransfer<AccountId> {
121	/// The quantity used to denote time; usually just a `BlockNumber`.
122	type Moment;
123
124	/// The currency that this schedule applies to.
125	type Currency: Currency<AccountId>;
126
127	/// Execute a vested transfer from `source` to `target` with the given schedule:
128	/// 	- `locked`: The amount to be transferred and for the vesting schedule to apply to.
129	/// 	- `per_block`: The amount to be unlocked each block. (linear vesting)
130	/// 	- `starting_block`: The block where the vesting should start. This block can be in the past
131	///    or future, and should adjust when the tokens become available to the user.
132	///
133	/// Example: Assume we are on block 100. If `locked` amount is 100, and `per_block` is 1:
134	/// 	- If `starting_block` is 0, then the whole 100 tokens will be available right away as the
135	///    vesting schedule started in the past and has fully completed.
136	/// 	- If `starting_block` is 50, then 50 tokens are made available right away, and 50 more
137	///    tokens will unlock one token at a time until block 150.
138	/// 	- If `starting_block` is 100, then each block, 1 token will be unlocked until the whole
139	///    balance is unlocked at block 200.
140	/// 	- If `starting_block` is 200, then the 100 token balance will be completely locked until
141	///    block 200, and then start to unlock one token at a time until block 300.
142	fn vested_transfer(
143		source: &AccountId,
144		target: &AccountId,
145		locked: <Self::Currency as Currency<AccountId>>::Balance,
146		per_block: <Self::Currency as Currency<AccountId>>::Balance,
147		starting_block: Self::Moment,
148	) -> DispatchResult;
149}
150
151// An no-op implementation of `VestedTransfer` for pallets that require this trait, but users may
152// not want to implement this functionality
153pub struct NoVestedTransfers<C> {
154	phantom: core::marker::PhantomData<C>,
155}
156
157impl<AccountId, C: Currency<AccountId>> VestedTransfer<AccountId> for NoVestedTransfers<C> {
158	type Moment = ();
159	type Currency = C;
160
161	fn vested_transfer(
162		_source: &AccountId,
163		_target: &AccountId,
164		_locked: <Self::Currency as Currency<AccountId>>::Balance,
165		_per_block: <Self::Currency as Currency<AccountId>>::Balance,
166		_starting_block: Self::Moment,
167	) -> DispatchResult {
168		Err(sp_runtime::DispatchError::Unavailable.into())
169	}
170}
frame_support/traits/tokens/currency/lockable.rs

frame_support/traits/tokens/currency/
lockable.rs
