| <!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/async-stream-impl-0.3.5/src/lib.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>lib.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="../../async_stream_impl/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="../../async_stream_impl/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>proc_macro::TokenStream; |
| <span class="kw">use </span>proc_macro2::{Group, TokenStream <span class="kw">as </span>TokenStream2, TokenTree}; |
| <span class="kw">use </span>quote::quote; |
| <span class="kw">use </span>syn::parse::{Parse, ParseStream, Parser, <span class="prelude-ty">Result</span>}; |
| <span class="kw">use </span>syn::visit_mut::VisitMut; |
| |
| <span class="kw">struct </span>Scrub<<span class="lifetime">'a</span>> { |
| <span class="doccomment">/// Whether the stream is a try stream. |
| </span>is_try: bool, |
| <span class="doccomment">/// The unit expression, `()`. |
| </span>unit: Box<syn::Expr>, |
| has_yielded: bool, |
| crate_path: <span class="kw-2">&</span><span class="lifetime">'a </span>TokenStream2, |
| } |
| |
| <span class="kw">fn </span>parse_input(input: TokenStream) -> syn::Result<(TokenStream2, Vec<syn::Stmt>)> { |
| <span class="kw">let </span><span class="kw-2">mut </span>input = TokenStream2::from(input).into_iter(); |
| <span class="kw">let </span>crate_path = <span class="kw">match </span>input.next().unwrap() { |
| TokenTree::Group(group) => group.stream(), |
| <span class="kw">_ </span>=> <span class="macro">panic!</span>(), |
| }; |
| <span class="kw">let </span>stmts = syn::Block::parse_within.parse2(replace_for_await(input))<span class="question-mark">?</span>; |
| <span class="prelude-val">Ok</span>((crate_path, stmts)) |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>> Scrub<<span class="lifetime">'a</span>> { |
| <span class="kw">fn </span>new(is_try: bool, crate_path: <span class="kw-2">&</span><span class="lifetime">'a </span>TokenStream2) -> <span class="self">Self </span>{ |
| <span class="self">Self </span>{ |
| is_try, |
| unit: <span class="macro">syn::parse_quote!</span>(()), |
| has_yielded: <span class="bool-val">false</span>, |
| crate_path, |
| } |
| } |
| } |
| |
| <span class="kw">struct </span>Partial<T>(T, TokenStream2); |
| |
| <span class="kw">impl</span><T: Parse> Parse <span class="kw">for </span>Partial<T> { |
| <span class="kw">fn </span>parse(input: ParseStream) -> <span class="prelude-ty">Result</span><<span class="self">Self</span>> { |
| <span class="prelude-val">Ok</span>(Partial(input.parse()<span class="question-mark">?</span>, input.parse()<span class="question-mark">?</span>)) |
| } |
| } |
| |
| <span class="kw">fn </span>visit_token_stream_impl( |
| visitor: <span class="kw-2">&mut </span>Scrub<<span class="lifetime">'_</span>>, |
| tokens: TokenStream2, |
| modified: <span class="kw-2">&mut </span>bool, |
| out: <span class="kw-2">&mut </span>TokenStream2, |
| ) { |
| <span class="kw">use </span>quote::ToTokens; |
| <span class="kw">use </span>quote::TokenStreamExt; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>tokens = tokens.into_iter().peekable(); |
| <span class="kw">while let </span><span class="prelude-val">Some</span>(tt) = tokens.next() { |
| <span class="kw">match </span>tt { |
| TokenTree::Ident(i) <span class="kw">if </span>i == <span class="string">"yield" </span>=> { |
| <span class="kw">let </span>stream = std::iter::once(TokenTree::Ident(i)).chain(tokens).collect(); |
| <span class="kw">match </span>syn::parse2(stream) { |
| <span class="prelude-val">Ok</span>(Partial(yield_expr, rest)) => { |
| <span class="kw">let </span><span class="kw-2">mut </span>expr = syn::Expr::Yield(yield_expr); |
| visitor.visit_expr_mut(<span class="kw-2">&mut </span>expr); |
| expr.to_tokens(out); |
| <span class="kw-2">*</span>modified = <span class="bool-val">true</span>; |
| tokens = rest.into_iter().peekable(); |
| } |
| <span class="prelude-val">Err</span>(e) => { |
| out.append_all(<span class="kw-2">&mut </span>e.to_compile_error().into_iter()); |
| <span class="kw-2">*</span>modified = <span class="bool-val">true</span>; |
| <span class="kw">return</span>; |
| } |
| } |
| } |
| TokenTree::Ident(i) <span class="kw">if </span>i == <span class="string">"stream" </span>|| i == <span class="string">"try_stream" </span>=> { |
| out.append(TokenTree::Ident(i)); |
| <span class="kw">match </span>tokens.peek() { |
| <span class="prelude-val">Some</span>(TokenTree::Punct(p)) <span class="kw">if </span>p.as_char() == <span class="string">'!' </span>=> { |
| out.extend(tokens.next()); <span class="comment">// ! |
| </span><span class="kw">if let </span><span class="prelude-val">Some</span>(TokenTree::Group(<span class="kw">_</span>)) = tokens.peek() { |
| out.extend(tokens.next()); <span class="comment">// { .. } or [ .. ] or ( .. ) |
| </span>} |
| } |
| <span class="kw">_ </span>=> {} |
| } |
| } |
| TokenTree::Group(group) => { |
| <span class="kw">let </span><span class="kw-2">mut </span>content = group.stream(); |
| <span class="kw-2">*</span>modified |= visitor.visit_token_stream(<span class="kw-2">&mut </span>content); |
| <span class="kw">let </span><span class="kw-2">mut </span>new = Group::new(group.delimiter(), content); |
| new.set_span(group.span()); |
| out.append(new); |
| } |
| other => out.append(other), |
| } |
| } |
| } |
| |
| <span class="kw">impl </span>Scrub<<span class="lifetime">'_</span>> { |
| <span class="kw">fn </span>visit_token_stream(<span class="kw-2">&mut </span><span class="self">self</span>, tokens: <span class="kw-2">&mut </span>TokenStream2) -> bool { |
| <span class="kw">let </span>(<span class="kw-2">mut </span>out, <span class="kw-2">mut </span>modified) = (TokenStream2::new(), <span class="bool-val">false</span>); |
| visit_token_stream_impl(<span class="self">self</span>, tokens.clone(), <span class="kw-2">&mut </span>modified, <span class="kw-2">&mut </span>out); |
| |
| <span class="kw">if </span>modified { |
| <span class="kw-2">*</span>tokens = out; |
| } |
| |
| modified |
| } |
| } |
| |
| <span class="kw">impl </span>VisitMut <span class="kw">for </span>Scrub<<span class="lifetime">'_</span>> { |
| <span class="kw">fn </span>visit_expr_mut(<span class="kw-2">&mut </span><span class="self">self</span>, i: <span class="kw-2">&mut </span>syn::Expr) { |
| <span class="kw">match </span>i { |
| syn::Expr::Yield(yield_expr) => { |
| <span class="self">self</span>.has_yielded = <span class="bool-val">true</span>; |
| |
| syn::visit_mut::visit_expr_yield_mut(<span class="self">self</span>, yield_expr); |
| |
| <span class="kw">let </span>value_expr = yield_expr.expr.as_ref().unwrap_or(<span class="kw-2">&</span><span class="self">self</span>.unit); |
| |
| <span class="comment">// let ident = &self.yielder; |
| |
| </span><span class="kw-2">*</span>i = <span class="kw">if </span><span class="self">self</span>.is_try { |
| <span class="macro">syn::parse_quote! </span>{ __yield_tx.send(::core::result::Result::Ok(#value_expr)).<span class="kw">await </span>} |
| } <span class="kw">else </span>{ |
| <span class="macro">syn::parse_quote! </span>{ __yield_tx.send(#value_expr).<span class="kw">await </span>} |
| }; |
| } |
| syn::Expr::Try(try_expr) => { |
| syn::visit_mut::visit_expr_try_mut(<span class="self">self</span>, try_expr); |
| <span class="comment">// let ident = &self.yielder; |
| </span><span class="kw">let </span>e = <span class="kw-2">&</span>try_expr.expr; |
| |
| <span class="kw-2">*</span>i = <span class="macro">syn::parse_quote! </span>{ |
| <span class="kw">match </span>#e { |
| ::core::result::Result::Ok(v) => v, |
| ::core::result::Result::Err(e) => { |
| __yield_tx.send(::core::result::Result::Err(e.into())).<span class="kw">await</span>; |
| <span class="kw">return</span>; |
| } |
| } |
| }; |
| } |
| syn::Expr::Closure(<span class="kw">_</span>) | syn::Expr::Async(<span class="kw">_</span>) => { |
| <span class="comment">// Don't transform inner closures or async blocks. |
| </span>} |
| syn::Expr::ForLoop(expr) => { |
| syn::visit_mut::visit_expr_for_loop_mut(<span class="self">self</span>, expr); |
| <span class="comment">// TODO: Should we allow other attributes? |
| </span><span class="kw">if </span>expr.attrs.len() != <span class="number">1 </span>|| !expr.attrs[<span class="number">0</span>].meta.path().is_ident(AWAIT_ATTR_NAME) { |
| <span class="kw">return</span>; |
| } |
| <span class="kw">let </span>syn::ExprForLoop { |
| attrs, |
| label, |
| pat, |
| expr, |
| body, |
| .. |
| } = expr; |
| |
| attrs.pop().unwrap(); |
| |
| <span class="kw">let </span>crate_path = <span class="self">self</span>.crate_path; |
| <span class="kw-2">*</span>i = <span class="macro">syn::parse_quote! </span>{{ |
| <span class="kw">let </span><span class="kw-2">mut </span>__pinned = #expr; |
| <span class="kw">let </span><span class="kw-2">mut </span>__pinned = <span class="kw">unsafe </span>{ |
| ::core::pin::Pin::new_unchecked(<span class="kw-2">&mut </span>__pinned) |
| }; |
| #label |
| <span class="kw">loop </span>{ |
| <span class="kw">let </span>#pat = <span class="kw">match </span>#crate_path::__private::next(<span class="kw-2">&mut </span>__pinned).<span class="kw">await </span>{ |
| ::core::option::Option::Some(e) => e, |
| ::core::option::Option::None => <span class="kw">break</span>, |
| }; |
| #body |
| } |
| }} |
| } |
| <span class="kw">_ </span>=> syn::visit_mut::visit_expr_mut(<span class="self">self</span>, i), |
| } |
| } |
| |
| <span class="kw">fn </span>visit_macro_mut(<span class="kw-2">&mut </span><span class="self">self</span>, mac: <span class="kw-2">&mut </span>syn::Macro) { |
| <span class="kw">let </span>mac_ident = mac.path.segments.last().map(|p| <span class="kw-2">&</span>p.ident); |
| <span class="kw">if </span>mac_ident.map_or(<span class="bool-val">false</span>, |i| i == <span class="string">"stream" </span>|| i == <span class="string">"try_stream"</span>) { |
| <span class="kw">return</span>; |
| } |
| |
| <span class="self">self</span>.visit_token_stream(<span class="kw-2">&mut </span>mac.tokens); |
| } |
| |
| <span class="kw">fn </span>visit_item_mut(<span class="kw-2">&mut </span><span class="self">self</span>, i: <span class="kw-2">&mut </span>syn::Item) { |
| <span class="comment">// Recurse into macros but otherwise don't transform inner items. |
| </span><span class="kw">if let </span>syn::Item::Macro(i) = i { |
| <span class="self">self</span>.visit_macro_mut(<span class="kw-2">&mut </span>i.mac); |
| } |
| } |
| } |
| |
| <span class="doccomment">/// The first token tree in the stream must be a group containing the path to the `async-stream` |
| /// crate. |
| </span><span class="attribute">#[proc_macro] |
| #[doc(hidden)] |
| </span><span class="kw">pub fn </span>stream_inner(input: TokenStream) -> TokenStream { |
| <span class="kw">let </span>(crate_path, <span class="kw-2">mut </span>stmts) = <span class="kw">match </span>parse_input(input) { |
| <span class="prelude-val">Ok</span>(x) => x, |
| <span class="prelude-val">Err</span>(e) => <span class="kw">return </span>e.to_compile_error().into(), |
| }; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>scrub = Scrub::new(<span class="bool-val">false</span>, <span class="kw-2">&</span>crate_path); |
| |
| <span class="kw">for </span>stmt <span class="kw">in </span><span class="kw-2">&mut </span>stmts { |
| scrub.visit_stmt_mut(stmt); |
| } |
| |
| <span class="kw">let </span>dummy_yield = <span class="kw">if </span>scrub.has_yielded { |
| <span class="prelude-val">None |
| </span>} <span class="kw">else </span>{ |
| <span class="prelude-val">Some</span>(<span class="macro">quote!</span>(<span class="kw">if </span><span class="bool-val">false </span>{ |
| __yield_tx.send(()).<span class="kw">await</span>; |
| })) |
| }; |
| |
| <span class="macro">quote!</span>({ |
| <span class="kw">let </span>(<span class="kw-2">mut </span>__yield_tx, __yield_rx) = <span class="kw">unsafe </span>{ #crate_path::__private::yielder::pair() }; |
| #crate_path::__private::AsyncStream::new(__yield_rx, <span class="kw">async move </span>{ |
| #dummy_yield |
| #(#stmts)* |
| }) |
| }) |
| .into() |
| } |
| |
| <span class="doccomment">/// The first token tree in the stream must be a group containing the path to the `async-stream` |
| /// crate. |
| </span><span class="attribute">#[proc_macro] |
| #[doc(hidden)] |
| </span><span class="kw">pub fn </span>try_stream_inner(input: TokenStream) -> TokenStream { |
| <span class="kw">let </span>(crate_path, <span class="kw-2">mut </span>stmts) = <span class="kw">match </span>parse_input(input) { |
| <span class="prelude-val">Ok</span>(x) => x, |
| <span class="prelude-val">Err</span>(e) => <span class="kw">return </span>e.to_compile_error().into(), |
| }; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>scrub = Scrub::new(<span class="bool-val">true</span>, <span class="kw-2">&</span>crate_path); |
| |
| <span class="kw">for </span>stmt <span class="kw">in </span><span class="kw-2">&mut </span>stmts { |
| scrub.visit_stmt_mut(stmt); |
| } |
| |
| <span class="kw">let </span>dummy_yield = <span class="kw">if </span>scrub.has_yielded { |
| <span class="prelude-val">None |
| </span>} <span class="kw">else </span>{ |
| <span class="prelude-val">Some</span>(<span class="macro">quote!</span>(<span class="kw">if </span><span class="bool-val">false </span>{ |
| __yield_tx.send(()).<span class="kw">await</span>; |
| })) |
| }; |
| |
| <span class="macro">quote!</span>({ |
| <span class="kw">let </span>(<span class="kw-2">mut </span>__yield_tx, __yield_rx) = <span class="kw">unsafe </span>{ #crate_path::__private::yielder::pair() }; |
| #crate_path::__private::AsyncStream::new(__yield_rx, <span class="kw">async move </span>{ |
| #dummy_yield |
| #(#stmts)* |
| }) |
| }) |
| .into() |
| } |
| |
| <span class="comment">// syn 2.0 wont parse `#[await] for x in xs {}` |
| // because `await` is a keyword, use `await_` instead |
| </span><span class="kw">const </span>AWAIT_ATTR_NAME: <span class="kw-2">&</span>str = <span class="string">"await_"</span>; |
| |
| <span class="doccomment">/// Replace `for await` with `#[await] for`, which will be later transformed into a `next` loop. |
| </span><span class="kw">fn </span>replace_for_await(input: <span class="kw">impl </span>IntoIterator<Item = TokenTree>) -> TokenStream2 { |
| <span class="kw">let </span><span class="kw-2">mut </span>input = input.into_iter().peekable(); |
| <span class="kw">let </span><span class="kw-2">mut </span>tokens = Vec::new(); |
| |
| <span class="kw">while let </span><span class="prelude-val">Some</span>(token) = input.next() { |
| <span class="kw">match </span>token { |
| TokenTree::Ident(ident) => { |
| <span class="kw">match </span>input.peek() { |
| <span class="prelude-val">Some</span>(TokenTree::Ident(next)) <span class="kw">if </span>ident == <span class="string">"for" </span>&& next == <span class="string">"await" </span>=> { |
| <span class="kw">let </span>next_span = next.span(); |
| <span class="kw">let </span>next = syn::Ident::new(AWAIT_ATTR_NAME, next_span); |
| tokens.extend(<span class="macro">quote!</span>(<span class="attribute">#[#next]</span>)); |
| <span class="kw">let _ </span>= input.next(); |
| } |
| <span class="kw">_ </span>=> {} |
| } |
| tokens.push(ident.into()); |
| } |
| TokenTree::Group(group) => { |
| <span class="kw">let </span>stream = replace_for_await(group.stream()); |
| <span class="kw">let </span><span class="kw-2">mut </span>new_group = Group::new(group.delimiter(), stream); |
| new_group.set_span(group.span()); |
| tokens.push(new_group.into()); |
| } |
| <span class="kw">_ </span>=> tokens.push(token), |
| } |
| } |
| |
| tokens.into_iter().collect() |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="async_stream_impl" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
