| <!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 `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/serde_derive-1.0.133/src/try.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>try.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" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../ayu.css" disabled><link rel="stylesheet" type="text/css" href="../../dark.css" disabled><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script src="../../crates.js"></script><script defer src="../../main.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script> |
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| <span id="2"> 2</span> |
| <span id="3"> 3</span> |
| <span id="4"> 4</span> |
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| </pre><pre class="rust"><code><span class="kw">use</span> <span class="ident">proc_macro2</span>::{<span class="ident">Punct</span>, <span class="ident">Spacing</span>, <span class="ident">TokenStream</span>}; |
| |
| <span class="comment">// None of our generated code requires the `From::from` error conversion</span> |
| <span class="comment">// performed by the standard library's `try!` macro. With this simplified macro</span> |
| <span class="comment">// we see a significant improvement in type checking and borrow checking time of</span> |
| <span class="comment">// the generated code and a slight improvement in binary size.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">replacement</span>() -> <span class="ident">TokenStream</span> { |
| <span class="comment">// Cannot pass `$expr` to `quote!` prior to Rust 1.17.0 so interpolate it.</span> |
| <span class="kw">let</span> <span class="ident">dollar</span> <span class="op">=</span> <span class="ident">Punct::new</span>(<span class="string">'$'</span>, <span class="ident">Spacing::Alone</span>); |
| |
| <span class="macro">quote!</span> { |
| <span class="attribute">#[<span class="ident">allow</span>(<span class="ident">unused_macros</span>)]</span> |
| <span class="macro">macro_rules!</span> <span class="ident">try</span> { |
| (#<span class="ident">dollar</span> <span class="ident">__expr</span>:<span class="ident">expr</span>) => { |
| <span class="kw">match</span> #<span class="ident">dollar</span> <span class="ident">__expr</span> { |
| <span class="ident">_serde::__private::Ok</span>(<span class="ident">__val</span>) => <span class="ident">__val</span>, |
| <span class="ident">_serde::__private::Err</span>(<span class="ident">__err</span>) => { |
| <span class="kw">return</span> <span class="ident">_serde::__private::Err</span>(<span class="ident">__err</span>); |
| } |
| } |
| } |
| } |
| } |
| } |
| </code></pre></div> |
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