mirror of
https://github.com/google/flatbuffers.git
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66 lines
2.4 KiB
Rust
66 lines
2.4 KiB
Rust
// Copyright 2019 Google LLC
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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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// https://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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use super::{Builder, MapBuilder, Pushable};
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/// Builds a Flexbuffer vector, returned by a [Builder](struct.Builder.html).
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///
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/// ## Side effect when dropped:
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/// When this is dropped, or `end_vector` is called, the vector is
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/// commited to the buffer. If this vector is the root of the flexbuffer, then the
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/// root is written and the flexbuffer is complete. The FlexBufferType of this vector
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/// is determined by the pushed values when this is dropped. The most compact vector type is
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/// automatically chosen.
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pub struct VectorBuilder<'a> {
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pub(crate) builder: &'a mut Builder,
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// If the root is this vector then start == None. Otherwise start is the
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// number of values in the 'values stack' before adding this vector.
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pub(crate) start: Option<usize>,
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}
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impl<'a> VectorBuilder<'a> {
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/// Pushes `p` onto the vector.
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#[inline]
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pub fn push<P: Pushable>(&mut self, p: P) {
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self.builder.push(p);
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}
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/// Starts a nested vector that will be pushed onto this vector when it is dropped.
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#[inline]
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pub fn start_vector(&mut self) -> VectorBuilder {
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let start = Some(self.builder.values.len());
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VectorBuilder {
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builder: self.builder,
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start,
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}
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}
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/// Starts a nested map that will be pushed onto this vector when it is dropped.
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#[inline]
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pub fn start_map(&mut self) -> MapBuilder {
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let start = Some(self.builder.values.len());
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MapBuilder {
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builder: self.builder,
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start,
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}
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}
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/// `end_vector` determines the type of the vector and writes it to the buffer.
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/// This will happen automatically if the VectorBuilder is dropped.
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#[inline]
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pub fn end_vector(self) {}
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}
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impl<'a> Drop for VectorBuilder<'a> {
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#[inline]
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fn drop(&mut self) {
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self.builder.end_map_or_vector(false, self.start);
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}
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}
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