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| </pre><pre class="rust"><code><span class="doccomment">/// Quasi-quotation macro that accepts input like the [`quote!`] macro but uses |
| /// type inference to figure out a return type for those tokens. |
| /// |
| /// [`quote!`]: https://docs.rs/quote/1.0/quote/index.html |
| /// |
| /// The return type can be any syntax tree node that implements the [`Parse`] |
| /// trait. |
| /// |
| /// [`Parse`]: crate::parse::Parse |
| /// |
| /// ``` |
| /// use quote::quote; |
| /// use syn::{parse_quote, Stmt}; |
| /// |
| /// fn main() { |
| /// let name = quote!(v); |
| /// let ty = quote!(u8); |
| /// |
| /// let stmt: Stmt = parse_quote! { |
| /// let #name: #ty = Default::default(); |
| /// }; |
| /// |
| /// println!("{:#?}", stmt); |
| /// } |
| /// ``` |
| /// |
| /// *This macro is available only if Syn is built with both the `"parsing"` and |
| /// `"printing"` features.* |
| /// |
| /// # Example |
| /// |
| /// The following helper function adds a bound `T: HeapSize` to every type |
| /// parameter `T` in the input generics. |
| /// |
| /// ``` |
| /// use syn::{parse_quote, Generics, GenericParam}; |
| /// |
| /// // Add a bound `T: HeapSize` to every type parameter T. |
| /// fn add_trait_bounds(mut generics: Generics) -> Generics { |
| /// for param in &mut generics.params { |
| /// if let GenericParam::Type(type_param) = param { |
| /// type_param.bounds.push(parse_quote!(HeapSize)); |
| /// } |
| /// } |
| /// generics |
| /// } |
| /// ``` |
| /// |
| /// # Special cases |
| /// |
| /// This macro can parse the following additional types as a special case even |
| /// though they do not implement the `Parse` trait. |
| /// |
| /// - [`Attribute`] — parses one attribute, allowing either outer like `#[...]` |
| /// or inner like `#![...]` |
| /// - [`Punctuated<T, P>`] — parses zero or more `T` separated by punctuation |
| /// `P` with optional trailing punctuation |
| /// - [`Vec<Stmt>`] — parses the same as `Block::parse_within` |
| /// |
| /// [`Vec<Stmt>`]: Block::parse_within |
| /// |
| /// # Panics |
| /// |
| /// Panics if the tokens fail to parse as the expected syntax tree type. The |
| /// caller is responsible for ensuring that the input tokens are syntactically |
| /// valid. |
| </span><span class="attribute">#[cfg_attr(doc_cfg, doc(cfg(all(feature = <span class="string">"parsing"</span>, feature = <span class="string">"printing"</span>))))] |
| #[macro_export] |
| </span><span class="macro">macro_rules! </span>parse_quote { |
| ($(<span class="macro-nonterminal">$tt</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro-nonterminal">$crate::__private::parse_quote</span>(<span class="macro-nonterminal">$</span><span class="macro">crate::__private::quote::quote!</span>($(<span class="macro-nonterminal">$tt</span>)<span class="kw-2">*</span>)) |
| }; |
| } |
| |
| <span class="doccomment">/// This macro is [`parse_quote!`] + [`quote_spanned!`][quote::quote_spanned]. |
| /// |
| /// Please refer to each of their documentation. |
| /// |
| /// # Example |
| /// |
| /// ``` |
| /// use quote::{quote, quote_spanned}; |
| /// use syn::spanned::Spanned; |
| /// use syn::{parse_quote_spanned, ReturnType, Signature}; |
| /// |
| /// // Changes `fn()` to `fn() -> Pin<Box<dyn Future<Output = ()>>>`, |
| /// // and `fn() -> T` to `fn() -> Pin<Box<dyn Future<Output = T>>>`, |
| /// // without introducing any call_site() spans. |
| /// fn make_ret_pinned_future(sig: &mut Signature) { |
| /// let ret = match &sig.output { |
| /// ReturnType::Default => quote_spanned!(sig.paren_token.span=> ()), |
| /// ReturnType::Type(_, ret) => quote!(#ret), |
| /// }; |
| /// sig.output = parse_quote_spanned! {ret.span()=> |
| /// -> ::std::pin::Pin<::std::boxed::Box<dyn ::std::future::Future<Output = #ret>>> |
| /// }; |
| /// } |
| /// ``` |
| </span><span class="attribute">#[cfg_attr(doc_cfg, doc(cfg(all(feature = <span class="string">"parsing"</span>, feature = <span class="string">"printing"</span>))))] |
| #[macro_export] |
| </span><span class="macro">macro_rules! </span>parse_quote_spanned { |
| (<span class="macro-nonterminal">$span</span>:expr=> $(<span class="macro-nonterminal">$tt</span>:tt)<span class="kw-2">*</span>) => { |
| <span class="macro-nonterminal">$crate::__private::parse_quote</span>(<span class="macro-nonterminal">$</span><span class="macro">crate::__private::quote::quote_spanned!</span>(<span class="macro-nonterminal">$span</span>=> $(<span class="macro-nonterminal">$tt</span>)<span class="kw-2">*</span>)) |
| }; |
| } |
| |
| <span class="comment">//////////////////////////////////////////////////////////////////////////////// |
| // Can parse any type that implements Parse. |
| |
| </span><span class="kw">use </span><span class="kw">crate</span>::parse::{Parse, ParseStream, Parser, <span class="prelude-ty">Result</span>}; |
| <span class="kw">use </span>proc_macro2::TokenStream; |
| |
| <span class="comment">// Not public API. |
| </span><span class="attribute">#[doc(hidden)] |
| </span><span class="kw">pub fn </span>parse<T: ParseQuote>(token_stream: TokenStream) -> T { |
| <span class="kw">let </span>parser = T::parse; |
| <span class="kw">match </span>parser.parse2(token_stream) { |
| <span class="prelude-val">Ok</span>(t) => t, |
| <span class="prelude-val">Err</span>(err) => <span class="macro">panic!</span>(<span class="string">"{}"</span>, err), |
| } |
| } |
| |
| <span class="kw">pub trait </span>ParseQuote: Sized { |
| <span class="kw">fn </span>parse(input: ParseStream) -> <span class="prelude-ty">Result</span><<span class="self">Self</span>>; |
| } |
| |
| <span class="kw">impl</span><T: Parse> ParseQuote <span class="kw">for </span>T { |
| <span class="kw">fn </span>parse(input: ParseStream) -> <span class="prelude-ty">Result</span><<span class="self">Self</span>> { |
| <T <span class="kw">as </span>Parse>::parse(input) |
| } |
| } |
| |
| <span class="comment">//////////////////////////////////////////////////////////////////////////////// |
| // Any other types that we want `parse_quote!` to be able to parse. |
| |
| </span><span class="kw">use </span><span class="kw">crate</span>::punctuated::Punctuated; |
| <span class="attribute">#[cfg(any(feature = <span class="string">"full"</span>, feature = <span class="string">"derive"</span>))] |
| </span><span class="kw">use crate</span>::{attr, Attribute}; |
| <span class="attribute">#[cfg(feature = <span class="string">"full"</span>)] |
| </span><span class="kw">use crate</span>::{Block, Pat, Stmt}; |
| |
| <span class="attribute">#[cfg(any(feature = <span class="string">"full"</span>, feature = <span class="string">"derive"</span>))] |
| </span><span class="kw">impl </span>ParseQuote <span class="kw">for </span>Attribute { |
| <span class="kw">fn </span>parse(input: ParseStream) -> <span class="prelude-ty">Result</span><<span class="self">Self</span>> { |
| <span class="kw">if </span>input.peek(<span class="macro">Token!</span>[#]) && input.peek2(<span class="macro">Token!</span>[!]) { |
| attr::parsing::single_parse_inner(input) |
| } <span class="kw">else </span>{ |
| attr::parsing::single_parse_outer(input) |
| } |
| } |
| } |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"full"</span>)] |
| </span><span class="kw">impl </span>ParseQuote <span class="kw">for </span>Pat { |
| <span class="kw">fn </span>parse(input: ParseStream) -> <span class="prelude-ty">Result</span><<span class="self">Self</span>> { |
| Pat::parse_multi_with_leading_vert(input) |
| } |
| } |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"full"</span>)] |
| </span><span class="kw">impl </span>ParseQuote <span class="kw">for </span>Box<Pat> { |
| <span class="kw">fn </span>parse(input: ParseStream) -> <span class="prelude-ty">Result</span><<span class="self">Self</span>> { |
| <Pat <span class="kw">as </span>ParseQuote>::parse(input).map(Box::new) |
| } |
| } |
| |
| <span class="kw">impl</span><T: Parse, P: Parse> ParseQuote <span class="kw">for </span>Punctuated<T, P> { |
| <span class="kw">fn </span>parse(input: ParseStream) -> <span class="prelude-ty">Result</span><<span class="self">Self</span>> { |
| <span class="self">Self</span>::parse_terminated(input) |
| } |
| } |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"full"</span>)] |
| </span><span class="kw">impl </span>ParseQuote <span class="kw">for </span>Vec<Stmt> { |
| <span class="kw">fn </span>parse(input: ParseStream) -> <span class="prelude-ty">Result</span><<span class="self">Self</span>> { |
| Block::parse_within(input) |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="syn" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |