| <!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="Declares a named parser which can easily be reused."><meta name="keywords" content="rust, rustlang, rust-lang, parser"><title>parser in combine - Rust</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="sidebar-items.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 macro"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle">☰</button><a class="sidebar-logo" href="../combine/index.html"><div class="logo-container"><img class="rust-logo" src="../rust-logo.svg" alt="logo"></div></a><h2></h2></nav><nav class="sidebar"><a class="sidebar-logo" href="../combine/index.html"><div class="logo-container"><img class="rust-logo" src="../rust-logo.svg" alt="logo"></div></a><div class="sidebar-elems"><h2><a href="index.html">In combine</a></h2></div></nav><main><div class="width-limiter"><nav class="sub"><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="main-heading"><h1 class="fqn">Macro <a href="index.html">combine</a>::<wbr><a class="macro" href="#">parser</a><button id="copy-path" onclick="copy_path(this)" title="Copy item path to clipboard"><img src="../clipboard.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="srclink" href="../src/combine/lib.rs.html#326-403">source</a> · <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div><div class="item-decl"><div class="example-wrap"><pre class="rust macro"><code><span class="macro">macro_rules! </span>parser { |
| ( |
| <span class="kw">type </span>PartialState = <span class="macro-nonterminal">$partial_state</span>: ty; |
| $(<span class="attribute">#[<span class="macro-nonterminal">$attr</span>:meta]</span>)* |
| <span class="macro-nonterminal">$fn_vis</span>: vis <span class="kw">fn </span><span class="macro-nonterminal">$name</span>: ident [$(<span class="macro-nonterminal">$type_params</span>: tt)<span class="kw-2">*</span>]( $(<span class="macro-nonterminal">$arg</span>: ident : <span class="macro-nonterminal">$arg_type</span>: ty),<span class="kw-2">*</span>) |
| (<span class="macro-nonterminal">$input_type</span>: ty) -> <span class="macro-nonterminal">$output_type</span>: ty |
| <span class="kw">where </span>[$(<span class="macro-nonterminal">$where_clause</span>: tt)<span class="kw-2">*</span>] |
| <span class="macro-nonterminal">$parser</span>: block |
| ) => { ... }; |
| ( |
| $(<span class="attribute">#[<span class="macro-nonterminal">$derive</span>:meta]</span>)* |
| <span class="macro-nonterminal">$struct_vis</span>: vis <span class="kw">struct </span><span class="macro-nonterminal">$type_name</span>: ident; |
| <span class="kw">type </span>PartialState = <span class="macro-nonterminal">$partial_state</span>: ty; |
| $(<span class="attribute">#[<span class="macro-nonterminal">$attr</span>:meta]</span>)* |
| <span class="macro-nonterminal">$fn_vis</span>: vis <span class="kw">fn </span><span class="macro-nonterminal">$name</span>: ident [$(<span class="macro-nonterminal">$type_params</span>: tt)<span class="kw-2">*</span>]( $(<span class="macro-nonterminal">$arg</span>: ident : <span class="macro-nonterminal">$arg_type</span>: ty),* ) |
| (<span class="macro-nonterminal">$input_type</span>: ty) -> <span class="macro-nonterminal">$output_type</span>: ty |
| <span class="kw">where </span>[$(<span class="macro-nonterminal">$where_clause</span>: tt)<span class="kw-2">*</span>] |
| <span class="macro-nonterminal">$parser</span>: block |
| ) => { ... }; |
| ( |
| $(<span class="attribute">#[<span class="macro-nonterminal">$attr</span>:meta]</span>)* |
| <span class="macro-nonterminal">$fn_vis</span>: vis <span class="kw">fn </span><span class="macro-nonterminal">$name</span>: ident [$(<span class="macro-nonterminal">$type_params</span>: tt)<span class="kw-2">*</span>]( $(<span class="macro-nonterminal">$arg</span>: ident : <span class="macro-nonterminal">$arg_type</span>: ty),<span class="kw-2">*</span>) |
| (<span class="macro-nonterminal">$input_type</span>: ty) -> <span class="macro-nonterminal">$output_type</span>: ty |
| <span class="kw">where </span>[$(<span class="macro-nonterminal">$where_clause</span>: tt)<span class="kw-2">*</span>] |
| <span class="macro-nonterminal">$parser</span>: block |
| ) => { ... }; |
| ( |
| $(<span class="attribute">#[<span class="macro-nonterminal">$derive</span>:meta]</span>)* |
| <span class="macro-nonterminal">$struct_vis</span>: vis <span class="kw">struct </span><span class="macro-nonterminal">$type_name</span>: ident; |
| $(<span class="attribute">#[<span class="macro-nonterminal">$attr</span>:meta]</span>)* |
| <span class="macro-nonterminal">$fn_vis</span>: vis <span class="kw">fn </span><span class="macro-nonterminal">$name</span>: ident [$(<span class="macro-nonterminal">$type_params</span>: tt)<span class="kw-2">*</span>]( $(<span class="macro-nonterminal">$arg</span>: ident : <span class="macro-nonterminal">$arg_type</span>: ty),* ) |
| (<span class="macro-nonterminal">$input_type</span>: ty) -> <span class="macro-nonterminal">$output_type</span>: ty |
| <span class="kw">where </span>[$(<span class="macro-nonterminal">$where_clause</span>: tt)<span class="kw-2">*</span>] |
| <span class="macro-nonterminal">$parser</span>: block |
| ) => { ... }; |
| }</code></pre></div> |
| </div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Declares a named parser which can easily be reused.</p> |
| <p>The expression which creates the parser should have no side effects as it may be called |
| multiple times even during a single parse attempt.</p> |
| <p>NOTE: If you are using rust nightly you can use <code>impl Trait</code> instead. See the <a href="https://github.com/Marwes/combine/blob/master/benches/json.rs">json parser</a> for |
| an example.</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="attribute">#[macro_use] |
| </span><span class="kw">extern crate </span>combine; |
| <span class="kw">use </span>combine::parser::char::digit; |
| <span class="kw">use </span>combine::{any, choice, from_str, many1, Parser, EasyParser, Stream}; |
| <span class="kw">use </span>combine::error::ParseError; |
| |
| <span class="macro">parser!</span>{ |
| <span class="doccomment">/// `[Input]` represents a normal type parameters and lifetime declaration for the function |
| /// It gets expanded to `<Input>` |
| </span><span class="kw">fn </span>integer[Input]()(Input) -> i32 |
| <span class="kw">where </span>[ |
| Input: Stream<Token = char>, |
| Input::Error: ParseError<char, Input::Range, Input::Position>, |
| <Input::Error <span class="kw">as </span>ParseError<Input::Token, Input::Range, Input::Position>>::StreamError: |
| From<::std::num::ParseIntError>, |
| ] |
| { |
| <span class="comment">// The body must be a block body ( `{ <block body> }`) which ends with an expression |
| // which evaluates to a parser |
| </span>from_str(many1::<String, <span class="kw">_</span>, <span class="kw">_</span>>(digit())) |
| } |
| } |
| |
| <span class="attribute">#[derive(Debug, PartialEq)] |
| </span><span class="kw">pub enum </span>IntOrString { |
| Int(i32), |
| String(String), |
| } |
| <span class="comment">// prefix with `pub` to declare a public parser |
| </span><span class="macro">parser!</span>{ |
| <span class="comment">// Documentation comments works as well |
| |
| </span><span class="doccomment">/// Parses an integer or a string (any characters) |
| </span><span class="kw">pub fn </span>integer_or_string[Input]()(Input) -> IntOrString |
| <span class="kw">where </span>[ |
| Input: Stream<Token = char>, |
| Input::Error: ParseError<char, Input::Range, Input::Position>, |
| <Input::Error <span class="kw">as </span>ParseError<Input::Token, Input::Range, Input::Position>>::StreamError: |
| From<::std::num::ParseIntError>, |
| ] |
| { |
| <span class="macro">choice!</span>( |
| integer().map(IntOrString::Int), |
| many1(any()).map(IntOrString::String) |
| ) |
| } |
| } |
| |
| <span class="macro">parser!</span>{ |
| <span class="comment">// Give the created type a unique name |
| </span><span class="attribute">#[derive(Clone)] |
| </span><span class="kw">pub struct </span>Twice; |
| <span class="kw">pub fn </span>twice[Input, F, P](f: F)(Input) -> (P::Output, P::Output) |
| <span class="kw">where </span>[P: Parser<Input>, |
| F: FnMut() -> P] |
| { |
| (f(), f()) |
| } |
| } |
| |
| <span class="kw">fn </span>main() { |
| <span class="macro">assert_eq!</span>(integer().easy_parse(<span class="string">"123"</span>), <span class="prelude-val">Ok</span>((<span class="number">123</span>, <span class="string">""</span>))); |
| <span class="macro">assert!</span>(integer().easy_parse(<span class="string">"!"</span>).is_err()); |
| |
| <span class="macro">assert_eq!</span>( |
| integer_or_string().easy_parse(<span class="string">"123"</span>), |
| <span class="prelude-val">Ok</span>((IntOrString::Int(<span class="number">123</span>), <span class="string">""</span>)) |
| ); |
| <span class="macro">assert_eq!</span>( |
| integer_or_string().easy_parse(<span class="string">"abc"</span>), |
| <span class="prelude-val">Ok</span>((IntOrString::String(<span class="string">"abc"</span>.to_string()), <span class="string">""</span>)) |
| ); |
| <span class="macro">assert_eq!</span>(twice(|| digit()).parse(<span class="string">"123"</span>), <span class="prelude-val">Ok</span>(((<span class="string">'1'</span>, <span class="string">'2'</span>), <span class="string">"3"</span>))); |
| }</code></pre></div> |
| </div></details></section></div></main><div id="rustdoc-vars" data-root-path="../" data-current-crate="combine" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
