use crate::error::Result; use crate::parse::ParseBuffer; use crate::token; use proc_macro2::{Delimiter, Span}; // Not public API. #[doc(hidden)] pub struct Parens<'a> { pub token: token::Paren, pub content: ParseBuffer<'a>, } // Not public API. #[doc(hidden)] pub struct Braces<'a> { pub token: token::Brace, pub content: ParseBuffer<'a>, } // Not public API. #[doc(hidden)] pub struct Brackets<'a> { pub token: token::Bracket, pub content: ParseBuffer<'a>, } // Not public API. #[cfg(any(feature = "full", feature = "derive"))] #[doc(hidden)] pub struct Group<'a> { pub token: token::Group, pub content: ParseBuffer<'a>, } // Not public API. #[doc(hidden)] pub fn parse_parens<'a>(input: &ParseBuffer<'a>) -> Result> { parse_delimited(input, Delimiter::Parenthesis).map(|(span, content)| Parens { token: token::Paren(span), content, }) } // Not public API. #[doc(hidden)] pub fn parse_braces<'a>(input: &ParseBuffer<'a>) -> Result> { parse_delimited(input, Delimiter::Brace).map(|(span, content)| Braces { token: token::Brace(span), content, }) } // Not public API. #[doc(hidden)] pub fn parse_brackets<'a>(input: &ParseBuffer<'a>) -> Result> { parse_delimited(input, Delimiter::Bracket).map(|(span, content)| Brackets { token: token::Bracket(span), content, }) } #[cfg(any(feature = "full", feature = "derive"))] pub(crate) fn parse_group<'a>(input: &ParseBuffer<'a>) -> Result> { parse_delimited(input, Delimiter::None).map(|(span, content)| Group { token: token::Group(span), content, }) } fn parse_delimited<'a>( input: &ParseBuffer<'a>, delimiter: Delimiter, ) -> Result<(Span, ParseBuffer<'a>)> { input.step(|cursor| { if let Some((content, span, rest)) = cursor.group(delimiter) { let scope = crate::buffer::close_span_of_group(*cursor); let nested = crate::parse::advance_step_cursor(cursor, content); let unexpected = crate::parse::get_unexpected(input); let content = crate::parse::new_parse_buffer(scope, nested, unexpected); Ok(((span, content), rest)) } else { let message = match delimiter { Delimiter::Parenthesis => "expected parentheses", Delimiter::Brace => "expected curly braces", Delimiter::Bracket => "expected square brackets", Delimiter::None => "expected invisible group", }; Err(cursor.error(message)) } }) } /// Parse a set of parentheses and expose their content to subsequent parsers. /// /// # Example /// /// ``` /// # use quote::quote; /// # /// use syn::{parenthesized, token, Ident, Result, Token, Type}; /// use syn::parse::{Parse, ParseStream}; /// use syn::punctuated::Punctuated; /// /// // Parse a simplified tuple struct syntax like: /// // /// // struct S(A, B); /// struct TupleStruct { /// struct_token: Token![struct], /// ident: Ident, /// paren_token: token::Paren, /// fields: Punctuated, /// semi_token: Token![;], /// } /// /// impl Parse for TupleStruct { /// fn parse(input: ParseStream) -> Result { /// let content; /// Ok(TupleStruct { /// struct_token: input.parse()?, /// ident: input.parse()?, /// paren_token: parenthesized!(content in input), /// fields: content.parse_terminated(Type::parse)?, /// semi_token: input.parse()?, /// }) /// } /// } /// # /// # fn main() { /// # let input = quote! { /// # struct S(A, B); /// # }; /// # syn::parse2::(input).unwrap(); /// # } /// ``` #[macro_export] #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] macro_rules! parenthesized { ($content:ident in $cursor:expr) => { match $crate::__private::parse_parens(&$cursor) { $crate::__private::Ok(parens) => { $content = parens.content; parens.token } $crate::__private::Err(error) => { return $crate::__private::Err(error); } } }; } /// Parse a set of curly braces and expose their content to subsequent parsers. /// /// # Example /// /// ``` /// # use quote::quote; /// # /// use syn::{braced, token, Ident, Result, Token, Type}; /// use syn::parse::{Parse, ParseStream}; /// use syn::punctuated::Punctuated; /// /// // Parse a simplified struct syntax like: /// // /// // struct S { /// // a: A, /// // b: B, /// // } /// struct Struct { /// struct_token: Token![struct], /// ident: Ident, /// brace_token: token::Brace, /// fields: Punctuated, /// } /// /// struct Field { /// name: Ident, /// colon_token: Token![:], /// ty: Type, /// } /// /// impl Parse for Struct { /// fn parse(input: ParseStream) -> Result { /// let content; /// Ok(Struct { /// struct_token: input.parse()?, /// ident: input.parse()?, /// brace_token: braced!(content in input), /// fields: content.parse_terminated(Field::parse)?, /// }) /// } /// } /// /// impl Parse for Field { /// fn parse(input: ParseStream) -> Result { /// Ok(Field { /// name: input.parse()?, /// colon_token: input.parse()?, /// ty: input.parse()?, /// }) /// } /// } /// # /// # fn main() { /// # let input = quote! { /// # struct S { /// # a: A, /// # b: B, /// # } /// # }; /// # syn::parse2::(input).unwrap(); /// # } /// ``` #[macro_export] #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] macro_rules! braced { ($content:ident in $cursor:expr) => { match $crate::__private::parse_braces(&$cursor) { $crate::__private::Ok(braces) => { $content = braces.content; braces.token } $crate::__private::Err(error) => { return $crate::__private::Err(error); } } }; } /// Parse a set of square brackets and expose their content to subsequent /// parsers. /// /// # Example /// /// ``` /// # use quote::quote; /// # /// use proc_macro2::TokenStream; /// use syn::{bracketed, token, Result, Token}; /// use syn::parse::{Parse, ParseStream}; /// /// // Parse an outer attribute like: /// // /// // #[repr(C, packed)] /// struct OuterAttribute { /// pound_token: Token![#], /// bracket_token: token::Bracket, /// content: TokenStream, /// } /// /// impl Parse for OuterAttribute { /// fn parse(input: ParseStream) -> Result { /// let content; /// Ok(OuterAttribute { /// pound_token: input.parse()?, /// bracket_token: bracketed!(content in input), /// content: content.parse()?, /// }) /// } /// } /// # /// # fn main() { /// # let input = quote! { /// # #[repr(C, packed)] /// # }; /// # syn::parse2::(input).unwrap(); /// # } /// ``` #[macro_export] #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] macro_rules! bracketed { ($content:ident in $cursor:expr) => { match $crate::__private::parse_brackets(&$cursor) { $crate::__private::Ok(brackets) => { $content = brackets.content; brackets.token } $crate::__private::Err(error) => { return $crate::__private::Err(error); } } }; }