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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 00:47:55 +0000
commit26a029d407be480d791972afb5975cf62c9360a6 (patch)
treef435a8308119effd964b339f76abb83a57c29483 /third_party/rust/syn/src/parse_quote.rs
parentInitial commit. (diff)
downloadfirefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz
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Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'third_party/rust/syn/src/parse_quote.rs')
-rw-r--r--third_party/rust/syn/src/parse_quote.rs209
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+/// 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.
+#[cfg_attr(doc_cfg, doc(cfg(all(feature = "parsing", feature = "printing"))))]
+#[macro_export]
+macro_rules! parse_quote {
+ ($($tt:tt)*) => {
+ $crate::__private::parse_quote($crate::__private::quote::quote!($($tt)*))
+ };
+}
+
+/// 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>>>
+/// };
+/// }
+/// ```
+#[cfg_attr(doc_cfg, doc(cfg(all(feature = "parsing", feature = "printing"))))]
+#[macro_export]
+macro_rules! parse_quote_spanned {
+ ($span:expr=> $($tt:tt)*) => {
+ $crate::__private::parse_quote($crate::__private::quote::quote_spanned!($span=> $($tt)*))
+ };
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Can parse any type that implements Parse.
+
+use crate::parse::{Parse, ParseStream, Parser, Result};
+use proc_macro2::TokenStream;
+
+// Not public API.
+#[doc(hidden)]
+pub fn parse<T: ParseQuote>(token_stream: TokenStream) -> T {
+ let parser = T::parse;
+ match parser.parse2(token_stream) {
+ Ok(t) => t,
+ Err(err) => panic!("{}", err),
+ }
+}
+
+#[doc(hidden)]
+pub trait ParseQuote: Sized {
+ fn parse(input: ParseStream) -> Result<Self>;
+}
+
+impl<T: Parse> ParseQuote for T {
+ fn parse(input: ParseStream) -> Result<Self> {
+ <T as Parse>::parse(input)
+ }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Any other types that we want `parse_quote!` to be able to parse.
+
+use crate::punctuated::Punctuated;
+#[cfg(any(feature = "full", feature = "derive"))]
+use crate::{attr, Attribute, Field, FieldMutability, Ident, Type, Visibility};
+#[cfg(feature = "full")]
+use crate::{Block, Pat, Stmt};
+
+#[cfg(any(feature = "full", feature = "derive"))]
+impl ParseQuote for Attribute {
+ fn parse(input: ParseStream) -> Result<Self> {
+ if input.peek(Token![#]) && input.peek2(Token![!]) {
+ attr::parsing::single_parse_inner(input)
+ } else {
+ attr::parsing::single_parse_outer(input)
+ }
+ }
+}
+
+#[cfg(any(feature = "full", feature = "derive"))]
+impl ParseQuote for Field {
+ fn parse(input: ParseStream) -> Result<Self> {
+ let attrs = input.call(Attribute::parse_outer)?;
+ let vis: Visibility = input.parse()?;
+
+ let ident: Option<Ident>;
+ let colon_token: Option<Token![:]>;
+ let is_named = input.peek(Ident) && input.peek2(Token![:]) && !input.peek2(Token![::]);
+ if is_named {
+ ident = Some(input.parse()?);
+ colon_token = Some(input.parse()?);
+ } else {
+ ident = None;
+ colon_token = None;
+ }
+
+ let ty: Type = input.parse()?;
+
+ Ok(Field {
+ attrs,
+ vis,
+ mutability: FieldMutability::None,
+ ident,
+ colon_token,
+ ty,
+ })
+ }
+}
+
+#[cfg(feature = "full")]
+impl ParseQuote for Pat {
+ fn parse(input: ParseStream) -> Result<Self> {
+ Pat::parse_multi_with_leading_vert(input)
+ }
+}
+
+#[cfg(feature = "full")]
+impl ParseQuote for Box<Pat> {
+ fn parse(input: ParseStream) -> Result<Self> {
+ <Pat as ParseQuote>::parse(input).map(Box::new)
+ }
+}
+
+impl<T: Parse, P: Parse> ParseQuote for Punctuated<T, P> {
+ fn parse(input: ParseStream) -> Result<Self> {
+ Self::parse_terminated(input)
+ }
+}
+
+#[cfg(feature = "full")]
+impl ParseQuote for Vec<Stmt> {
+ fn parse(input: ParseStream) -> Result<Self> {
+ Block::parse_within(input)
+ }
+}