| <!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/futures-util-0.3.28/src/io/empty.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>empty.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="../../../futures_util/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="../../../futures_util/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>futures_core::task::{Context, Poll}; |
| <span class="kw">use </span>futures_io::{AsyncBufRead, AsyncRead}; |
| <span class="kw">use </span>std::fmt; |
| <span class="kw">use </span>std::io; |
| <span class="kw">use </span>std::pin::Pin; |
| |
| <span class="doccomment">/// Reader for the [`empty()`] function. |
| </span><span class="attribute">#[must_use = <span class="string">"readers do nothing unless polled"</span>] |
| </span><span class="kw">pub struct </span>Empty { |
| _priv: (), |
| } |
| |
| <span class="doccomment">/// Constructs a new handle to an empty reader. |
| /// |
| /// All reads from the returned reader will return `Poll::Ready(Ok(0))`. |
| /// |
| /// # Examples |
| /// |
| /// A slightly sad example of not reading anything into a buffer: |
| /// |
| /// ``` |
| /// # futures::executor::block_on(async { |
| /// use futures::io::{self, AsyncReadExt}; |
| /// |
| /// let mut buffer = String::new(); |
| /// let mut reader = io::empty(); |
| /// reader.read_to_string(&mut buffer).await?; |
| /// assert!(buffer.is_empty()); |
| /// # Ok::<(), Box<dyn std::error::Error>>(()) }).unwrap(); |
| /// ``` |
| </span><span class="kw">pub fn </span>empty() -> Empty { |
| Empty { _priv: () } |
| } |
| |
| <span class="kw">impl </span>AsyncRead <span class="kw">for </span>Empty { |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>poll_read( |
| <span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, |
| <span class="kw">_</span>: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>, |
| <span class="kw">_</span>: <span class="kw-2">&mut </span>[u8], |
| ) -> Poll<io::Result<usize>> { |
| Poll::Ready(<span class="prelude-val">Ok</span>(<span class="number">0</span>)) |
| } |
| } |
| |
| <span class="kw">impl </span>AsyncBufRead <span class="kw">for </span>Empty { |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>poll_fill_buf(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, <span class="kw">_</span>: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<io::Result<<span class="kw-2">&</span>[u8]>> { |
| Poll::Ready(<span class="prelude-val">Ok</span>(<span class="kw-2">&</span>[])) |
| } |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>consume(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, <span class="kw">_</span>: usize) {} |
| } |
| |
| <span class="kw">impl </span>fmt::Debug <span class="kw">for </span>Empty { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.pad(<span class="string">"Empty { .. }"</span>) |
| } |
| } |
| </code></pre></div> |
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