| <!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/pin-utils-0.1.0/src/projection.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>projection.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="../../pin_utils/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="../../pin_utils/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="doccomment">/// A pinned projection of a struct field. |
| /// |
| /// # Safety |
| /// |
| /// To make using this macro safe, three things need to be ensured: |
| /// - If the struct implements [`Drop`], the [`drop`] method is not allowed to |
| /// move the value of the field. |
| /// - If the struct wants to implement [`Unpin`], it has to do so conditionally: |
| /// The struct can only implement [`Unpin`] if the field's type is [`Unpin`]. |
| /// - The struct must not be `#[repr(packed)]`. |
| /// |
| /// # Example |
| /// |
| /// ```rust |
| /// use pin_utils::unsafe_pinned; |
| /// use std::marker::Unpin; |
| /// use std::pin::Pin; |
| /// |
| /// struct Foo<T> { |
| /// field: T, |
| /// } |
| /// |
| /// impl<T> Foo<T> { |
| /// unsafe_pinned!(field: T); |
| /// |
| /// fn baz(mut self: Pin<&mut Self>) { |
| /// let _: Pin<&mut T> = self.field(); // Pinned reference to the field |
| /// } |
| /// } |
| /// |
| /// impl<T: Unpin> Unpin for Foo<T> {} // Conditional Unpin impl |
| /// ``` |
| /// |
| /// Note: borrowing the field multiple times requires using `.as_mut()` to |
| /// avoid consuming the `Pin`. |
| /// |
| /// [`Unpin`]: core::marker::Unpin |
| /// [`drop`]: Drop::drop |
| </span><span class="attribute">#[macro_export] |
| </span><span class="macro">macro_rules! </span>unsafe_pinned { |
| (<span class="macro-nonterminal">$f</span>:tt: <span class="macro-nonterminal">$t</span>:ty) => ( |
| <span class="attribute">#[allow(unsafe_code)] |
| </span><span class="kw">fn </span><span class="macro-nonterminal">$f</span><<span class="lifetime">'__a</span>>( |
| <span class="self">self</span>: <span class="macro-nonterminal">$crate::core_reexport::pin::Pin</span><<span class="kw-2">&</span><span class="lifetime">'__a </span><span class="kw-2">mut </span><span class="self">Self</span>> |
| ) -> <span class="macro-nonterminal">$crate::core_reexport::pin::Pin</span><<span class="kw-2">&</span><span class="lifetime">'__a </span><span class="kw-2">mut </span><span class="macro-nonterminal">$t</span>> { |
| <span class="kw">unsafe </span>{ |
| <span class="macro-nonterminal">$crate::core_reexport::pin::Pin::map_unchecked_mut</span>( |
| <span class="self">self</span>, |x| <span class="kw-2">&mut </span>x.<span class="macro-nonterminal">$f |
| </span>) |
| } |
| } |
| ) |
| } |
| |
| <span class="doccomment">/// An unpinned projection of a struct field. |
| /// |
| /// # Safety |
| /// |
| /// This macro is unsafe because it creates a method that returns a normal |
| /// non-pin reference to the struct field. It is up to the programmer to ensure |
| /// that the contained value can be considered not pinned in the current |
| /// context. |
| /// |
| /// # Example |
| /// |
| /// ```rust |
| /// use pin_utils::unsafe_unpinned; |
| /// use std::pin::Pin; |
| /// |
| /// struct Bar; |
| /// struct Foo { |
| /// field: Bar, |
| /// } |
| /// |
| /// impl Foo { |
| /// unsafe_unpinned!(field: Bar); |
| /// |
| /// fn baz(mut self: Pin<&mut Self>) { |
| /// let _: &mut Bar = self.field(); // Normal reference to the field |
| /// } |
| /// } |
| /// ``` |
| /// |
| /// Note: borrowing the field multiple times requires using `.as_mut()` to |
| /// avoid consuming the [`Pin`]. |
| /// |
| /// [`Pin`]: core::pin::Pin |
| </span><span class="attribute">#[macro_export] |
| </span><span class="macro">macro_rules! </span>unsafe_unpinned { |
| (<span class="macro-nonterminal">$f</span>:tt: <span class="macro-nonterminal">$t</span>:ty) => ( |
| <span class="attribute">#[allow(unsafe_code)] |
| </span><span class="kw">fn </span><span class="macro-nonterminal">$f</span><<span class="lifetime">'__a</span>>( |
| <span class="self">self</span>: <span class="macro-nonterminal">$crate::core_reexport::pin::Pin</span><<span class="kw-2">&</span><span class="lifetime">'__a </span><span class="kw-2">mut </span><span class="self">Self</span>> |
| ) -> <span class="kw-2">&</span><span class="lifetime">'__a </span><span class="kw-2">mut </span><span class="macro-nonterminal">$t </span>{ |
| <span class="kw">unsafe </span>{ |
| <span class="kw-2">&mut </span><span class="macro-nonterminal">$crate::core_reexport::pin::Pin::get_unchecked_mut</span>(<span class="self">self</span>).<span class="macro-nonterminal">$f |
| </span>} |
| } |
| ) |
| } |
| </code></pre></div> |
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