mirror of
https://github.com/pezkuwichain/pezkuwi-subxt.git
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Gav
99 lines
3.0 KiB
Rust
99 lines
3.0 KiB
Rust
// Copyright 2017 Parity Technologies (UK) Ltd.
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// This file is part of Polkadot.
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// Polkadot is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Polkadot is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
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//! Serialisation.
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use runtime_support::{Vec, size_of, transmute, uninitialized, slice};
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use joiner::Joiner;
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use endiansensitive::EndianSensitive;
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/// Trait that allows zero-copy read/write of value-references to/from slices in LE format.
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pub trait Slicable: Sized {
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fn from_slice(value: &[u8]) -> Option<Self> {
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Self::set_as_slice(&|out, offset| if value.len() >= out.len() + offset {
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let value = &value[offset..];
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let len = out.len();
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out.copy_from_slice(&value[0..len]);
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true
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} else {
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false
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})
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}
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fn to_vec(&self) -> Vec<u8> {
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self.as_slice_then(|s| s.to_vec())
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}
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fn set_as_slice<F: Fn(&mut[u8], usize) -> bool>(set_slice: &F) -> Option<Self>;
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fn as_slice_then<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
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f(&self.to_vec())
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}
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fn size_of(_value: &[u8]) -> Option<usize>;
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}
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/// Trait to mark that a type is not trivially (essentially "in place") serialisable.
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pub trait NonTrivialSlicable: Slicable {}
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impl<T: EndianSensitive> Slicable for T {
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fn set_as_slice<F: Fn(&mut[u8], usize) -> bool>(fill_slice: &F) -> Option<Self> {
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let size = size_of::<T>();
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let mut result: T = unsafe { uninitialized() };
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let result_slice = unsafe {
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slice::from_raw_parts_mut(transmute::<*mut T, *mut u8>(&mut result), size)
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};
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if fill_slice(result_slice, 0) {
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Some(result.from_le())
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} else {
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None
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}
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}
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fn as_slice_then<R, F: FnOnce(&[u8]) -> R>(&self, f: F) -> R {
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let size = size_of::<Self>();
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self.as_le_then(|le| {
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let value_slice = unsafe {
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slice::from_raw_parts(transmute::<*const Self, *const u8>(le), size)
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};
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f(value_slice)
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})
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}
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fn size_of(_value: &[u8]) -> Option<usize> {
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Some(size_of::<Self>())
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}
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}
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impl Slicable for Vec<u8> {
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fn from_slice(value: &[u8]) -> Option<Self> {
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Some(value[4..].to_vec())
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}
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fn set_as_slice<F: Fn(&mut[u8], usize) -> bool>(fill_slice: &F) -> Option<Self> {
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u32::set_as_slice(fill_slice).and_then(|len| {
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let mut v = Vec::with_capacity(len as usize);
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unsafe { v.set_len(len as usize); }
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if fill_slice(&mut v, 4) {
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Some(v)
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} else {
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None
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}
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})
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}
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fn to_vec(&self) -> Vec<u8> {
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let mut r: Vec<u8> = Vec::new().join(&(self.len() as u32));
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r.extend_from_slice(&self);
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r
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}
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fn size_of(data: &[u8]) -> Option<usize> {
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u32::from_slice(&data[0..4]).map(|i| (i + 4) as usize)
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}
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}
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