forked from BigfootDev/flatbuffers
3c54fd964b
This is a port of FlatBuffers to Rust. It provides code generation and a runtime library derived from the C++ implementation. It utilizes the Rust type system to provide safe and fast traversal of FlatBuffers data. There are 188 tests, including many fuzz tests of roundtrips for various serialization scenarios. Initial benchmarks indicate that the canonical example payload can be written in ~700ns, and traversed in ~100ns. Rustaceans may be interested in the Follow, Push, and SafeSliceAccess traits. These traits lift traversals, reads, writes, and slice accesses into the type system, providing abstraction with no runtime penalty.
82 lines
2.3 KiB
Rust
82 lines
2.3 KiB
Rust
/*
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* Copyright 2018 Google Inc. All rights reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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use std::cmp::max;
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use std::mem::{align_of, size_of};
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use endian_scalar::emplace_scalar;
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/// Trait to abstract over functionality needed to write values (either owned
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/// or referenced). Used in FlatBufferBuilder and implemented for generated
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/// types.
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pub trait Push: Sized {
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type Output;
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fn push(&self, dst: &mut [u8], _rest: &[u8]);
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#[inline]
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fn size() -> usize {
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size_of::<Self::Output>()
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}
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#[inline]
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fn alignment() -> PushAlignment {
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PushAlignment::new(align_of::<Self::Output>())
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}
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}
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/// Ensure Push alignment calculations are typesafe (because this helps reduce
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/// implementation issues when using FlatBufferBuilder::align).
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pub struct PushAlignment(usize);
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impl PushAlignment {
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#[inline]
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pub fn new(x: usize) -> Self {
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PushAlignment { 0: x }
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}
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#[inline]
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pub fn value(&self) -> usize {
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self.0
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}
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#[inline]
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pub fn max_of(&self, o: usize) -> Self {
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PushAlignment::new(max(self.0, o))
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}
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}
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/// Macro to implement Push for EndianScalar types.
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macro_rules! impl_push_for_endian_scalar {
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($ty:ident) => (
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impl Push for $ty {
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type Output = $ty;
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#[inline]
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fn push(&self, dst: &mut [u8], _rest: &[u8]) {
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emplace_scalar::<$ty>(dst, *self);
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}
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}
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)
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}
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impl_push_for_endian_scalar!(bool);
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impl_push_for_endian_scalar!(u8);
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impl_push_for_endian_scalar!(i8);
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impl_push_for_endian_scalar!(u16);
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impl_push_for_endian_scalar!(i16);
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impl_push_for_endian_scalar!(u32);
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impl_push_for_endian_scalar!(i32);
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impl_push_for_endian_scalar!(u64);
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impl_push_for_endian_scalar!(i64);
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impl_push_for_endian_scalar!(f32);
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impl_push_for_endian_scalar!(f64);
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