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.
63 lines
2.1 KiB
Rust
63 lines
2.1 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::marker::PhantomData;
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/// Follow is a trait that allows us to access FlatBuffers in a declarative,
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/// type safe, and fast way. They compile down to almost no code (after
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/// optimizations). Conceptually, Follow lifts the offset-based access
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/// patterns of FlatBuffers data into the type system. This trait is used
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/// pervasively at read time, to access tables, vtables, vectors, strings, and
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/// all other data. At this time, Follow is not utilized much on the write
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/// path.
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///
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/// Writing a new Follow implementation primarily involves deciding whether
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/// you want to return data (of the type Self::Inner) or do you want to
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/// continue traversing the FlatBuffer.
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pub trait Follow<'a> {
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type Inner;
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fn follow(buf: &'a [u8], loc: usize) -> Self::Inner;
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}
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/// Execute a follow as a top-level function.
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#[allow(dead_code)]
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#[inline]
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pub fn lifted_follow<'a, T: Follow<'a>>(buf: &'a [u8], loc: usize) -> T::Inner {
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T::follow(buf, loc)
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}
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/// FollowStart wraps a Follow impl in a struct type. This can make certain
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/// programming patterns more ergonomic.
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#[derive(Debug)]
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pub struct FollowStart<T>(PhantomData<T>);
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impl<'a, T: Follow<'a> + 'a> FollowStart<T> {
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#[inline]
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pub fn new() -> Self {
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Self { 0: PhantomData }
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}
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#[inline]
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pub fn self_follow(&'a self, buf: &'a [u8], loc: usize) -> T::Inner {
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T::follow(buf, loc)
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}
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}
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impl<'a, T: Follow<'a>> Follow<'a> for FollowStart<T> {
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type Inner = T::Inner;
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#[inline]
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fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
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T::follow(buf, loc)
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}
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}
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