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Diffstat (limited to 'vendor/syn/src/parse_quote.rs')
| -rw-r--r-- | vendor/syn/src/parse_quote.rs | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/vendor/syn/src/parse_quote.rs b/vendor/syn/src/parse_quote.rs new file mode 100644 index 0000000..18de474 --- /dev/null +++ b/vendor/syn/src/parse_quote.rs @@ -0,0 +1,209 @@ +/// 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) + } +} |