forked from BigfootDev/flatbuffers
374f8fb5fb
* Rust soundness fixes * Second pass * Make init_from_table unsafe * Remove SafeSliceAccess * Clippy * Remove create_vector_of_strings * More clippy * Remove deprecated root type accessors * More soundness fixes * Fix EndianScalar for bool * Add TriviallyTransmutable * Add debug assertions * Review comments * Review feedback
64 lines
2.2 KiB
Rust
64 lines
2.2 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 core::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<'buf> {
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type Inner;
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/// # Safety
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///
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/// `buf[loc..]` must contain a valid value of `Self` and anything it
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/// transitively refers to by offset must also be valid
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unsafe fn follow(buf: &'buf [u8], loc: usize) -> Self::Inner;
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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, Default)]
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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(PhantomData)
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}
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/// # Safety
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///
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/// `buf[loc..]` must contain a valid value of `T`
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#[inline]
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pub unsafe 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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unsafe 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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