| <!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 `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.28.2/src/io/util/read_line.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>read_line.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../../normalize.css"><link rel="stylesheet" href="../../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../../ayu.css" disabled><link rel="stylesheet" href="../../../../dark.css" disabled><link rel="stylesheet" href="../../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../../storage.js"></script><script defer src="../../../../source-script.js"></script><script defer src="../../../../source-files.js"></script><script defer src="../../../../main.js"></script><noscript><link rel="stylesheet" href="../../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../../tokio/index.html"><div class="logo-container"><img class="rust-logo" src="../../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../../tokio/index.html"><img class="rust-logo" src="../../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="kw">use </span><span class="kw">crate</span>::io::util::read_until::read_until_internal; |
| <span class="kw">use </span><span class="kw">crate</span>::io::AsyncBufRead; |
| |
| <span class="kw">use </span>pin_project_lite::pin_project; |
| <span class="kw">use </span>std::future::Future; |
| <span class="kw">use </span>std::io; |
| <span class="kw">use </span>std::marker::PhantomPinned; |
| <span class="kw">use </span>std::mem; |
| <span class="kw">use </span>std::pin::Pin; |
| <span class="kw">use </span>std::string::FromUtf8Error; |
| <span class="kw">use </span>std::task::{Context, Poll}; |
| |
| <span class="macro">pin_project! </span>{ |
| <span class="doccomment">/// Future for the [`read_line`](crate::io::AsyncBufReadExt::read_line) method. |
| </span><span class="attribute">#[derive(Debug)] |
| #[must_use = <span class="string">"futures do nothing unless you `.await` or poll them"</span>] |
| </span><span class="kw">pub struct </span>ReadLine<<span class="lifetime">'a</span>, R: <span class="question-mark">?</span>Sized> { |
| reader: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>R, |
| <span class="comment">// This is the buffer we were provided. It will be replaced with an empty string |
| // while reading to postpone utf-8 handling until after reading. |
| </span>output: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>String, |
| <span class="comment">// The actual allocation of the string is moved into this vector instead. |
| </span>buf: Vec<u8>, |
| <span class="comment">// The number of bytes appended to buf. This can be less than buf.len() if |
| // the buffer was not empty when the operation was started. |
| </span>read: usize, |
| <span class="comment">// Make this future `!Unpin` for compatibility with async trait methods. |
| </span><span class="attribute">#[pin] |
| </span>_pin: PhantomPinned, |
| } |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>read_line<<span class="lifetime">'a</span>, R>(reader: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>R, string: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>String) -> ReadLine<<span class="lifetime">'a</span>, R> |
| <span class="kw">where |
| </span>R: AsyncBufRead + <span class="question-mark">?</span>Sized + Unpin, |
| { |
| ReadLine { |
| reader, |
| buf: mem::take(string).into_bytes(), |
| output: string, |
| read: <span class="number">0</span>, |
| _pin: PhantomPinned, |
| } |
| } |
| |
| <span class="kw">fn </span>put_back_original_data(output: <span class="kw-2">&mut </span>String, <span class="kw-2">mut </span>vector: Vec<u8>, num_bytes_read: usize) { |
| <span class="kw">let </span>original_len = vector.len() - num_bytes_read; |
| vector.truncate(original_len); |
| <span class="kw-2">*</span>output = String::from_utf8(vector).expect(<span class="string">"The original data must be valid utf-8."</span>); |
| } |
| |
| <span class="doccomment">/// This handles the various failure cases and puts the string back into `output`. |
| /// |
| /// The `truncate_on_io_error` bool is necessary because `read_to_string` and `read_line` |
| /// disagree on what should happen when an IO error occurs. |
| </span><span class="kw">pub</span>(<span class="kw">super</span>) <span class="kw">fn </span>finish_string_read( |
| io_res: io::Result<usize>, |
| utf8_res: <span class="prelude-ty">Result</span><String, FromUtf8Error>, |
| read: usize, |
| output: <span class="kw-2">&mut </span>String, |
| truncate_on_io_error: bool, |
| ) -> Poll<io::Result<usize>> { |
| <span class="kw">match </span>(io_res, utf8_res) { |
| (<span class="prelude-val">Ok</span>(num_bytes), <span class="prelude-val">Ok</span>(string)) => { |
| <span class="macro">debug_assert_eq!</span>(read, <span class="number">0</span>); |
| <span class="kw-2">*</span>output = string; |
| Poll::Ready(<span class="prelude-val">Ok</span>(num_bytes)) |
| } |
| (<span class="prelude-val">Err</span>(io_err), <span class="prelude-val">Ok</span>(string)) => { |
| <span class="kw-2">*</span>output = string; |
| <span class="kw">if </span>truncate_on_io_error { |
| <span class="kw">let </span>original_len = output.len() - read; |
| output.truncate(original_len); |
| } |
| Poll::Ready(<span class="prelude-val">Err</span>(io_err)) |
| } |
| (<span class="prelude-val">Ok</span>(num_bytes), <span class="prelude-val">Err</span>(utf8_err)) => { |
| <span class="macro">debug_assert_eq!</span>(read, <span class="number">0</span>); |
| put_back_original_data(output, utf8_err.into_bytes(), num_bytes); |
| |
| Poll::Ready(<span class="prelude-val">Err</span>(io::Error::new( |
| io::ErrorKind::InvalidData, |
| <span class="string">"stream did not contain valid UTF-8"</span>, |
| ))) |
| } |
| (<span class="prelude-val">Err</span>(io_err), <span class="prelude-val">Err</span>(utf8_err)) => { |
| put_back_original_data(output, utf8_err.into_bytes(), read); |
| |
| Poll::Ready(<span class="prelude-val">Err</span>(io_err)) |
| } |
| } |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">super</span>) <span class="kw">fn </span>read_line_internal<R: AsyncBufRead + <span class="question-mark">?</span>Sized>( |
| reader: Pin<<span class="kw-2">&mut </span>R>, |
| cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>, |
| output: <span class="kw-2">&mut </span>String, |
| buf: <span class="kw-2">&mut </span>Vec<u8>, |
| read: <span class="kw-2">&mut </span>usize, |
| ) -> Poll<io::Result<usize>> { |
| <span class="kw">let </span>io_res = <span class="macro">ready!</span>(read_until_internal(reader, cx, <span class="string">b'\n'</span>, buf, read)); |
| <span class="kw">let </span>utf8_res = String::from_utf8(mem::take(buf)); |
| |
| <span class="comment">// At this point both buf and output are empty. The allocation is in utf8_res. |
| |
| </span><span class="macro">debug_assert!</span>(buf.is_empty()); |
| <span class="macro">debug_assert!</span>(output.is_empty()); |
| finish_string_read(io_res, utf8_res, <span class="kw-2">*</span>read, output, <span class="bool-val">false</span>) |
| } |
| |
| <span class="kw">impl</span><R: AsyncBufRead + <span class="question-mark">?</span>Sized + Unpin> Future <span class="kw">for </span>ReadLine<<span class="lifetime">'_</span>, R> { |
| <span class="kw">type </span>Output = io::Result<usize>; |
| |
| <span class="kw">fn </span>poll(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="self">Self</span>::Output> { |
| <span class="kw">let </span>me = <span class="self">self</span>.project(); |
| |
| read_line_internal(Pin::new(<span class="kw-2">*</span>me.reader), cx, me.output, me.buf, me.read) |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../../" data-current-crate="tokio" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
