| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `arrow-buffer/src/builder/mod.rs`."><title>mod.rs - source</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-46f98efaafac5295.ttf.woff2,FiraSans-Regular-018c141bf0843ffd.woff2,FiraSans-Medium-8f9a781e4970d388.woff2,SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2,SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2" crossorigin href="../../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../../../static.files/rustdoc-dd39b87e5fcfba68.css"><meta name="rustdoc-vars" data-root-path="../../../" data-static-root-path="../../../static.files/" data-current-crate="arrow_buffer" data-themes="" data-resource-suffix="" data-rustdoc-version="1.80.0-nightly (8c127df75 2024-05-16)" data-channel="nightly" data-search-js="search-d52510db62a78183.js" data-settings-js="settings-4313503d2e1961c2.js" ><script src="../../../static.files/storage-118b08c4c78b968e.js"></script><script defer src="../../../static.files/src-script-e66d777a5a92e9b2.js"></script><script defer src="../../../src-files.js"></script><script defer src="../../../static.files/main-20a3ad099b048cf2.js"></script><noscript><link rel="stylesheet" href="../../../static.files/noscript-df360f571f6edeae.css"></noscript><link rel="alternate icon" type="image/png" href="../../../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../../../static.files/favicon-2c020d218678b618.svg"></head><body class="rustdoc src"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="src-sidebar-title"><h2>Files</h2></div></nav><div class="sidebar-resizer"></div><main><rustdoc-search></rustdoc-search><section id="main-content" class="content"><div class="example-wrap"><div data-nosnippet><pre class="src-line-numbers"><a href="#1" id="1">1</a> |
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| <a href="#412" id="412">412</a> |
| <a href="#413" id="413">413</a> |
| <a href="#414" id="414">414</a> |
| <a href="#415" id="415">415</a> |
| <a href="#416" id="416">416</a> |
| <a href="#417" id="417">417</a> |
| <a href="#418" id="418">418</a> |
| <a href="#419" id="419">419</a> |
| <a href="#420" id="420">420</a> |
| <a href="#421" id="421">421</a> |
| </pre></div><pre class="rust"><code><span class="comment">// Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you under the Apache License, Version 2.0 (the |
| // "License"); you may not use this file except in compliance |
| // with the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, |
| // software distributed under the License is distributed on an |
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| // KIND, either express or implied. See the License for the |
| // specific language governing permissions and limitations |
| // under the License. |
| |
| </span><span class="doccomment">//! Buffer builders |
| |
| </span><span class="kw">mod </span>boolean; |
| <span class="kw">mod </span>null; |
| <span class="kw">mod </span>offset; |
| |
| <span class="kw">pub use </span>boolean::<span class="kw-2">*</span>; |
| <span class="kw">pub use </span>null::<span class="kw-2">*</span>; |
| <span class="kw">pub use </span>offset::<span class="kw-2">*</span>; |
| |
| <span class="kw">use crate</span>::{ArrowNativeType, Buffer, MutableBuffer}; |
| <span class="kw">use </span>std::{iter, marker::PhantomData}; |
| |
| <span class="doccomment">/// Builder for creating a [Buffer] object. |
| /// |
| /// A [Buffer] is the underlying data structure of Arrow's Arrays. |
| /// |
| /// For all supported types, there are type definitions for the |
| /// generic version of `BufferBuilder<T>`, e.g. `BufferBuilder`. |
| /// |
| /// # Example: |
| /// |
| /// ``` |
| /// # use arrow_buffer::builder::BufferBuilder; |
| /// |
| /// let mut builder = BufferBuilder::<u8>::new(100); |
| /// builder.append_slice(&[42, 43, 44]); |
| /// builder.append(45); |
| /// let buffer = builder.finish(); |
| /// |
| /// assert_eq!(unsafe { buffer.typed_data::<u8>() }, &[42, 43, 44, 45]); |
| /// ``` |
| </span><span class="attr">#[derive(Debug)] |
| </span><span class="kw">pub struct </span>BufferBuilder<T: ArrowNativeType> { |
| buffer: MutableBuffer, |
| len: usize, |
| _marker: PhantomData<T>, |
| } |
| |
| <span class="kw">impl</span><T: ArrowNativeType> BufferBuilder<T> { |
| <span class="doccomment">/// Creates a new builder with initial capacity for _at least_ `capacity` |
| /// elements of type `T`. |
| /// |
| /// The capacity can later be manually adjusted with the |
| /// [`reserve()`](BufferBuilder::reserve) method. |
| /// Also the |
| /// [`append()`](BufferBuilder::append), |
| /// [`append_slice()`](BufferBuilder::append_slice) and |
| /// [`advance()`](BufferBuilder::advance) |
| /// methods automatically increase the capacity if needed. |
| /// |
| /// # Example: |
| /// |
| /// ``` |
| /// # use arrow_buffer::builder::BufferBuilder; |
| /// |
| /// let mut builder = BufferBuilder::<u8>::new(10); |
| /// |
| /// assert!(builder.capacity() >= 10); |
| /// ``` |
| </span><span class="attr">#[inline] |
| </span><span class="kw">pub fn </span>new(capacity: usize) -> <span class="self">Self </span>{ |
| <span class="kw">let </span>buffer = MutableBuffer::new(capacity * std::mem::size_of::<T>()); |
| |
| <span class="self">Self </span>{ |
| buffer, |
| len: <span class="number">0</span>, |
| _marker: PhantomData, |
| } |
| } |
| |
| <span class="doccomment">/// Creates a new builder from a [`MutableBuffer`] |
| </span><span class="kw">pub fn </span>new_from_buffer(buffer: MutableBuffer) -> <span class="self">Self </span>{ |
| <span class="kw">let </span>buffer_len = buffer.len(); |
| <span class="self">Self </span>{ |
| buffer, |
| len: buffer_len / std::mem::size_of::<T>(), |
| _marker: PhantomData, |
| } |
| } |
| |
| <span class="doccomment">/// Returns the current number of array elements in the internal buffer. |
| /// |
| /// # Example: |
| /// |
| /// ``` |
| /// # use arrow_buffer::builder::BufferBuilder; |
| /// |
| /// let mut builder = BufferBuilder::<u8>::new(10); |
| /// builder.append(42); |
| /// |
| /// assert_eq!(builder.len(), 1); |
| /// ``` |
| </span><span class="kw">pub fn </span>len(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="self">self</span>.len |
| } |
| |
| <span class="doccomment">/// Returns whether the internal buffer is empty. |
| /// |
| /// # Example: |
| /// |
| /// ``` |
| /// # use arrow_buffer::builder::BufferBuilder; |
| /// |
| /// let mut builder = BufferBuilder::<u8>::new(10); |
| /// builder.append(42); |
| /// |
| /// assert_eq!(builder.is_empty(), false); |
| /// ``` |
| </span><span class="kw">pub fn </span>is_empty(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="self">self</span>.len == <span class="number">0 |
| </span>} |
| |
| <span class="doccomment">/// Returns the actual capacity (number of elements) of the internal buffer. |
| /// |
| /// Note: the internal capacity returned by this method might be larger than |
| /// what you'd expect after setting the capacity in the `new()` or `reserve()` |
| /// functions. |
| </span><span class="kw">pub fn </span>capacity(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="kw">let </span>byte_capacity = <span class="self">self</span>.buffer.capacity(); |
| byte_capacity / std::mem::size_of::<T>() |
| } |
| |
| <span class="doccomment">/// Increases the number of elements in the internal buffer by `n` |
| /// and resizes the buffer as needed. |
| /// |
| /// The values of the newly added elements are 0. |
| /// This method is usually used when appending `NULL` values to the buffer |
| /// as they still require physical memory space. |
| /// |
| /// # Example: |
| /// |
| /// ``` |
| /// # use arrow_buffer::builder::BufferBuilder; |
| /// |
| /// let mut builder = BufferBuilder::<u8>::new(10); |
| /// builder.advance(2); |
| /// |
| /// assert_eq!(builder.len(), 2); |
| /// ``` |
| </span><span class="attr">#[inline] |
| </span><span class="kw">pub fn </span>advance(<span class="kw-2">&mut </span><span class="self">self</span>, i: usize) { |
| <span class="self">self</span>.buffer.extend_zeros(i * std::mem::size_of::<T>()); |
| <span class="self">self</span>.len += i; |
| } |
| |
| <span class="doccomment">/// Reserves memory for _at least_ `n` more elements of type `T`. |
| /// |
| /// # Example: |
| /// |
| /// ``` |
| /// # use arrow_buffer::builder::BufferBuilder; |
| /// |
| /// let mut builder = BufferBuilder::<u8>::new(10); |
| /// builder.reserve(10); |
| /// |
| /// assert!(builder.capacity() >= 20); |
| /// ``` |
| </span><span class="attr">#[inline] |
| </span><span class="kw">pub fn </span>reserve(<span class="kw-2">&mut </span><span class="self">self</span>, n: usize) { |
| <span class="self">self</span>.buffer.reserve(n * std::mem::size_of::<T>()); |
| } |
| |
| <span class="doccomment">/// Appends a value of type `T` into the builder, |
| /// growing the internal buffer as needed. |
| /// |
| /// # Example: |
| /// |
| /// ``` |
| /// # use arrow_buffer::builder::BufferBuilder; |
| /// |
| /// let mut builder = BufferBuilder::<u8>::new(10); |
| /// builder.append(42); |
| /// |
| /// assert_eq!(builder.len(), 1); |
| /// ``` |
| </span><span class="attr">#[inline] |
| </span><span class="kw">pub fn </span>append(<span class="kw-2">&mut </span><span class="self">self</span>, v: T) { |
| <span class="self">self</span>.reserve(<span class="number">1</span>); |
| <span class="self">self</span>.buffer.push(v); |
| <span class="self">self</span>.len += <span class="number">1</span>; |
| } |
| |
| <span class="doccomment">/// Appends a value of type `T` into the builder N times, |
| /// growing the internal buffer as needed. |
| /// |
| /// # Example: |
| /// |
| /// ``` |
| /// # use arrow_buffer::builder::BufferBuilder; |
| /// |
| /// let mut builder = BufferBuilder::<u8>::new(10); |
| /// builder.append_n(10, 42); |
| /// |
| /// assert_eq!(builder.len(), 10); |
| /// ``` |
| </span><span class="attr">#[inline] |
| </span><span class="kw">pub fn </span>append_n(<span class="kw-2">&mut </span><span class="self">self</span>, n: usize, v: T) { |
| <span class="self">self</span>.reserve(n); |
| <span class="self">self</span>.extend(iter::repeat(v).take(n)) |
| } |
| |
| <span class="doccomment">/// Appends `n`, zero-initialized values |
| /// |
| /// # Example: |
| /// |
| /// ``` |
| /// # use arrow_buffer::builder::BufferBuilder; |
| /// |
| /// let mut builder = BufferBuilder::<u32>::new(10); |
| /// builder.append_n_zeroed(3); |
| /// |
| /// assert_eq!(builder.len(), 3); |
| /// assert_eq!(builder.as_slice(), &[0, 0, 0]) |
| </span><span class="attr">#[inline] |
| </span><span class="kw">pub fn </span>append_n_zeroed(<span class="kw-2">&mut </span><span class="self">self</span>, n: usize) { |
| <span class="self">self</span>.buffer.extend_zeros(n * std::mem::size_of::<T>()); |
| <span class="self">self</span>.len += n; |
| } |
| |
| <span class="doccomment">/// Appends a slice of type `T`, growing the internal buffer as needed. |
| /// |
| /// # Example: |
| /// |
| /// ``` |
| /// # use arrow_buffer::builder::BufferBuilder; |
| /// |
| /// let mut builder = BufferBuilder::<u8>::new(10); |
| /// builder.append_slice(&[42, 44, 46]); |
| /// |
| /// assert_eq!(builder.len(), 3); |
| /// ``` |
| </span><span class="attr">#[inline] |
| </span><span class="kw">pub fn </span>append_slice(<span class="kw-2">&mut </span><span class="self">self</span>, slice: <span class="kw-2">&</span>[T]) { |
| <span class="self">self</span>.buffer.extend_from_slice(slice); |
| <span class="self">self</span>.len += slice.len(); |
| } |
| |
| <span class="doccomment">/// View the contents of this buffer as a slice |
| /// |
| /// ``` |
| /// # use arrow_buffer::builder::BufferBuilder; |
| /// |
| /// let mut builder = BufferBuilder::<f64>::new(10); |
| /// builder.append(1.3); |
| /// builder.append_n(2, 2.3); |
| /// |
| /// assert_eq!(builder.as_slice(), &[1.3, 2.3, 2.3]); |
| /// ``` |
| </span><span class="attr">#[inline] |
| </span><span class="kw">pub fn </span>as_slice(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>[T] { |
| <span class="comment">// SAFETY |
| // |
| // - MutableBuffer is aligned and initialized for len elements of T |
| // - MutableBuffer corresponds to a single allocation |
| // - MutableBuffer does not support modification whilst active immutable borrows |
| </span><span class="kw">unsafe </span>{ std::slice::from_raw_parts(<span class="self">self</span>.buffer.as_ptr() <span class="kw">as _</span>, <span class="self">self</span>.len) } |
| } |
| |
| <span class="doccomment">/// View the contents of this buffer as a mutable slice |
| /// |
| /// # Example: |
| /// |
| /// ``` |
| /// # use arrow_buffer::builder::BufferBuilder; |
| /// |
| /// let mut builder = BufferBuilder::<f32>::new(10); |
| /// |
| /// builder.append_slice(&[1., 2., 3.4]); |
| /// assert_eq!(builder.as_slice(), &[1., 2., 3.4]); |
| /// |
| /// builder.as_slice_mut()[1] = 4.2; |
| /// assert_eq!(builder.as_slice(), &[1., 4.2, 3.4]); |
| /// ``` |
| </span><span class="attr">#[inline] |
| </span><span class="kw">pub fn </span>as_slice_mut(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw-2">&mut </span>[T] { |
| <span class="comment">// SAFETY |
| // |
| // - MutableBuffer is aligned and initialized for len elements of T |
| // - MutableBuffer corresponds to a single allocation |
| // - MutableBuffer does not support modification whilst active immutable borrows |
| </span><span class="kw">unsafe </span>{ std::slice::from_raw_parts_mut(<span class="self">self</span>.buffer.as_mut_ptr() <span class="kw">as _</span>, <span class="self">self</span>.len) } |
| } |
| |
| <span class="doccomment">/// Shorten this BufferBuilder to `len` items |
| /// |
| /// If `len` is greater than the builder's current length, this has no effect |
| /// |
| /// # Example: |
| /// |
| /// ``` |
| /// # use arrow_buffer::builder::BufferBuilder; |
| /// |
| /// let mut builder = BufferBuilder::<u16>::new(10); |
| /// |
| /// builder.append_slice(&[42, 44, 46]); |
| /// assert_eq!(builder.as_slice(), &[42, 44, 46]); |
| /// |
| /// builder.truncate(2); |
| /// assert_eq!(builder.as_slice(), &[42, 44]); |
| /// |
| /// builder.append(12); |
| /// assert_eq!(builder.as_slice(), &[42, 44, 12]); |
| /// ``` |
| </span><span class="attr">#[inline] |
| </span><span class="kw">pub fn </span>truncate(<span class="kw-2">&mut </span><span class="self">self</span>, len: usize) { |
| <span class="self">self</span>.buffer.truncate(len * std::mem::size_of::<T>()); |
| <span class="self">self</span>.len = len; |
| } |
| |
| <span class="doccomment">/// # Safety |
| /// This requires the iterator be a trusted length. This could instead require |
| /// the iterator implement `TrustedLen` once that is stabilized. |
| </span><span class="attr">#[inline] |
| </span><span class="kw">pub unsafe fn </span>append_trusted_len_iter(<span class="kw-2">&mut </span><span class="self">self</span>, iter: <span class="kw">impl </span>IntoIterator<Item = T>) { |
| <span class="kw">let </span>iter = iter.into_iter(); |
| <span class="kw">let </span>len = iter |
| .size_hint() |
| .<span class="number">1 |
| </span>.expect(<span class="string">"append_trusted_len_iter expects upper bound"</span>); |
| <span class="self">self</span>.reserve(len); |
| <span class="self">self</span>.extend(iter); |
| } |
| |
| <span class="doccomment">/// Resets this builder and returns an immutable [Buffer]. |
| /// |
| /// # Example: |
| /// |
| /// ``` |
| /// # use arrow_buffer::builder::BufferBuilder; |
| /// |
| /// let mut builder = BufferBuilder::<u8>::new(10); |
| /// builder.append_slice(&[42, 44, 46]); |
| /// |
| /// let buffer = builder.finish(); |
| /// |
| /// assert_eq!(unsafe { buffer.typed_data::<u8>() }, &[42, 44, 46]); |
| /// ``` |
| </span><span class="attr">#[inline] |
| </span><span class="kw">pub fn </span>finish(<span class="kw-2">&mut </span><span class="self">self</span>) -> Buffer { |
| <span class="kw">let </span>buf = std::mem::take(<span class="kw-2">&mut </span><span class="self">self</span>.buffer); |
| <span class="self">self</span>.len = <span class="number">0</span>; |
| buf.into() |
| } |
| } |
| |
| <span class="kw">impl</span><T: ArrowNativeType> Default <span class="kw">for </span>BufferBuilder<T> { |
| <span class="kw">fn </span>default() -> <span class="self">Self </span>{ |
| <span class="self">Self</span>::new(<span class="number">0</span>) |
| } |
| } |
| |
| <span class="kw">impl</span><T: ArrowNativeType> Extend<T> <span class="kw">for </span>BufferBuilder<T> { |
| <span class="kw">fn </span>extend<I: IntoIterator<Item = T>>(<span class="kw-2">&mut </span><span class="self">self</span>, iter: I) { |
| <span class="self">self</span>.buffer.extend(iter.into_iter().inspect(|<span class="kw">_</span>| { |
| <span class="self">self</span>.len += <span class="number">1</span>; |
| })) |
| } |
| } |
| |
| <span class="kw">impl</span><T: ArrowNativeType> From<Vec<T>> <span class="kw">for </span>BufferBuilder<T> { |
| <span class="kw">fn </span>from(value: Vec<T>) -> <span class="self">Self </span>{ |
| <span class="self">Self</span>::new_from_buffer(MutableBuffer::from(value)) |
| } |
| } |
| |
| <span class="kw">impl</span><T: ArrowNativeType> FromIterator<T> <span class="kw">for </span>BufferBuilder<T> { |
| <span class="kw">fn </span>from_iter<I: IntoIterator<Item = T>>(iter: I) -> <span class="self">Self </span>{ |
| <span class="kw">let </span><span class="kw-2">mut </span>builder = <span class="self">Self</span>::default(); |
| builder.extend(iter); |
| builder |
| } |
| } |
| |
| <span class="attr">#[cfg(test)] |
| </span><span class="kw">mod </span>tests { |
| <span class="kw">use super</span>::<span class="kw-2">*</span>; |
| <span class="kw">use </span>std::mem; |
| |
| <span class="attr">#[test] |
| </span><span class="kw">fn </span>default() { |
| <span class="kw">let </span>builder = BufferBuilder::<u32>::default(); |
| <span class="macro">assert!</span>(builder.is_empty()); |
| <span class="macro">assert!</span>(builder.buffer.is_empty()); |
| <span class="macro">assert_eq!</span>(builder.buffer.capacity(), <span class="number">0</span>); |
| } |
| |
| <span class="attr">#[test] |
| </span><span class="kw">fn </span>from_iter() { |
| <span class="kw">let </span>input = [<span class="number">1u16</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>]; |
| <span class="kw">let </span>builder = input.into_iter().collect::<BufferBuilder<<span class="kw">_</span>>>(); |
| <span class="macro">assert_eq!</span>(builder.len(), <span class="number">4</span>); |
| <span class="macro">assert_eq!</span>(builder.buffer.len(), <span class="number">4 </span>* mem::size_of::<u16>()); |
| } |
| |
| <span class="attr">#[test] |
| </span><span class="kw">fn </span>extend() { |
| <span class="kw">let </span>input = [<span class="number">1</span>, <span class="number">2</span>]; |
| <span class="kw">let </span><span class="kw-2">mut </span>builder = input.into_iter().collect::<BufferBuilder<<span class="kw">_</span>>>(); |
| <span class="macro">assert_eq!</span>(builder.len(), <span class="number">2</span>); |
| builder.extend([<span class="number">3</span>, <span class="number">4</span>]); |
| <span class="macro">assert_eq!</span>(builder.len(), <span class="number">4</span>); |
| } |
| } |
| </code></pre></div></section></main></body></html> |
