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* implement BoundedEncodedLen * update header * update imports * use impl_for_tuples instead of a custom macro * remove redundant where clause Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com> * impl for Compact<T> * impl BoundedEncodedLen for BoundedVec (#8727) * impl BoundedEncodedLen for bool * explicitly implement BoundedEncodedLen for each Compact form Turns out that u16 doesn't play nicely with the pattern; those values take two extra bytes, where all other cases take one. :( * rename BoundedEncodedLen -> MaxEncodedLen * add tests of compact encoded length Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>
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// This file is part of Substrate. | ||
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// Copyright (C) 2019-2021 Parity Technologies (UK) Ltd. | ||
// SPDX-License-Identifier: Apache-2.0 | ||
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// 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. | ||
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use codec::{Compact, Encode}; | ||
use impl_trait_for_tuples::impl_for_tuples; | ||
use sp_std::{mem, marker::PhantomData}; | ||
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/// Items implementing `MaxEncodedLen` have a statically known maximum encoded size. | ||
/// | ||
/// Some containers, such as `BoundedVec`, have enforced size limits and this trait | ||
/// can be implemented accurately. Other containers, such as `StorageMap`, do not have enforced size | ||
/// limits. For those containers, it is necessary to make a documented assumption about the maximum | ||
/// usage, and compute the max encoded length based on that assumption. | ||
pub trait MaxEncodedLen: Encode { | ||
/// Upper bound, in bytes, of the maximum encoded size of this item. | ||
fn max_encoded_len() -> usize; | ||
} | ||
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macro_rules! impl_primitives { | ||
( $($t:ty),+ ) => { | ||
$( | ||
impl MaxEncodedLen for $t { | ||
fn max_encoded_len() -> usize { | ||
mem::size_of::<$t>() | ||
} | ||
} | ||
)+ | ||
}; | ||
} | ||
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impl_primitives!(u8, u16, u32, u64, u128, i8, i16, i32, i64, i128, bool); | ||
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macro_rules! impl_compact { | ||
($( $t:ty => $e:expr; )*) => { | ||
$( | ||
impl MaxEncodedLen for Compact<$t> { | ||
fn max_encoded_len() -> usize { | ||
$e | ||
} | ||
} | ||
)* | ||
}; | ||
} | ||
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impl_compact!( | ||
// https://github.com/paritytech/parity-scale-codec/blob/f0341dabb01aa9ff0548558abb6dcc5c31c669a1/src/compact.rs#L261 | ||
u8 => 2; | ||
// https://github.com/paritytech/parity-scale-codec/blob/f0341dabb01aa9ff0548558abb6dcc5c31c669a1/src/compact.rs#L291 | ||
u16 => 4; | ||
// https://github.com/paritytech/parity-scale-codec/blob/f0341dabb01aa9ff0548558abb6dcc5c31c669a1/src/compact.rs#L326 | ||
u32 => 5; | ||
// https://github.com/paritytech/parity-scale-codec/blob/f0341dabb01aa9ff0548558abb6dcc5c31c669a1/src/compact.rs#L369 | ||
u64 => 9; | ||
// https://github.com/paritytech/parity-scale-codec/blob/f0341dabb01aa9ff0548558abb6dcc5c31c669a1/src/compact.rs#L413 | ||
u128 => 17; | ||
); | ||
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// impl_for_tuples for values 19 and higher fails because that's where the WrapperTypeEncode impl stops. | ||
#[impl_for_tuples(18)] | ||
impl MaxEncodedLen for Tuple { | ||
fn max_encoded_len() -> usize { | ||
let mut len: usize = 0; | ||
for_tuples!( #( len = len.saturating_add(Tuple::max_encoded_len()); )* ); | ||
len | ||
} | ||
} | ||
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impl<T: MaxEncodedLen, const N: usize> MaxEncodedLen for [T; N] { | ||
fn max_encoded_len() -> usize { | ||
T::max_encoded_len().saturating_mul(N) | ||
} | ||
} | ||
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impl<T: MaxEncodedLen> MaxEncodedLen for Option<T> { | ||
fn max_encoded_len() -> usize { | ||
T::max_encoded_len().saturating_add(1) | ||
} | ||
} | ||
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impl<T, E> MaxEncodedLen for Result<T, E> | ||
where | ||
T: MaxEncodedLen, | ||
E: MaxEncodedLen, | ||
{ | ||
fn max_encoded_len() -> usize { | ||
T::max_encoded_len().max(E::max_encoded_len()).saturating_add(1) | ||
} | ||
} | ||
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impl<T> MaxEncodedLen for PhantomData<T> { | ||
fn max_encoded_len() -> usize { | ||
0 | ||
} | ||
} | ||
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#[cfg(test)] | ||
mod tests { | ||
use super::*; | ||
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macro_rules! test_compact_length { | ||
($(fn $name:ident($t:ty);)*) => { | ||
$( | ||
#[test] | ||
fn $name() { | ||
assert_eq!(Compact(<$t>::MAX).encode().len(), Compact::<$t>::max_encoded_len()); | ||
} | ||
)* | ||
}; | ||
} | ||
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test_compact_length!( | ||
fn compact_u8(u8); | ||
fn compact_u16(u16); | ||
fn compact_u32(u32); | ||
fn compact_u64(u64); | ||
fn compact_u128(u128); | ||
); | ||
} |