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Diffstat (limited to 'third_party/rust/syn/src/group.rs')
| -rw-r--r-- | third_party/rust/syn/src/group.rs | 282 |
1 files changed, 282 insertions, 0 deletions
diff --git a/third_party/rust/syn/src/group.rs b/third_party/rust/syn/src/group.rs new file mode 100644 index 0000000000..7fd273c1de --- /dev/null +++ b/third_party/rust/syn/src/group.rs @@ -0,0 +1,282 @@ +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<Parens<'a>> { + 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<Braces<'a>> { + 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<Brackets<'a>> { + 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<Group<'a>> { + 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<Type, Token![,]>, +/// semi_token: Token![;], +/// } +/// +/// impl Parse for TupleStruct { +/// fn parse(input: ParseStream) -> Result<Self> { +/// 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::<TupleStruct>(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 $crate::__private::Err(error); + } + } + }; +} + +/// Parse a set of curly braces and expose their content to subsequent parsers. +/// +/// # Example +/// +/// ``` +/// # use quote::quote; +/// # +/// use syn::{braced, token, Ident, Result, Token, Type}; +/// use syn::parse::{Parse, ParseStream}; +/// use syn::punctuated::Punctuated; +/// +/// // Parse a simplified struct syntax like: +/// // +/// // struct S { +/// // a: A, +/// // b: B, +/// // } +/// struct Struct { +/// struct_token: Token![struct], +/// ident: Ident, +/// brace_token: token::Brace, +/// fields: Punctuated<Field, Token![,]>, +/// } +/// +/// struct Field { +/// name: Ident, +/// colon_token: Token![:], +/// ty: Type, +/// } +/// +/// impl Parse for Struct { +/// fn parse(input: ParseStream) -> Result<Self> { +/// let content; +/// Ok(Struct { +/// struct_token: input.parse()?, +/// ident: input.parse()?, +/// brace_token: braced!(content in input), +/// fields: content.parse_terminated(Field::parse)?, +/// }) +/// } +/// } +/// +/// impl Parse for Field { +/// fn parse(input: ParseStream) -> Result<Self> { +/// Ok(Field { +/// name: input.parse()?, +/// colon_token: input.parse()?, +/// ty: input.parse()?, +/// }) +/// } +/// } +/// # +/// # fn main() { +/// # let input = quote! { +/// # struct S { +/// # a: A, +/// # b: B, +/// # } +/// # }; +/// # syn::parse2::<Struct>(input).unwrap(); +/// # } +/// ``` +#[macro_export] +#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] +macro_rules! braced { + ($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 $crate::__private::Err(error); + } + } + }; +} + +/// Parse a set of square brackets and expose their content to subsequent +/// parsers. +/// +/// # Example +/// +/// ``` +/// # use quote::quote; +/// # +/// use proc_macro2::TokenStream; +/// use syn::{bracketed, token, Result, Token}; +/// use syn::parse::{Parse, ParseStream}; +/// +/// // Parse an outer attribute like: +/// // +/// // #[repr(C, packed)] +/// struct OuterAttribute { +/// pound_token: Token![#], +/// bracket_token: token::Bracket, +/// content: TokenStream, +/// } +/// +/// impl Parse for OuterAttribute { +/// fn parse(input: ParseStream) -> Result<Self> { +/// let content; +/// Ok(OuterAttribute { +/// pound_token: input.parse()?, +/// bracket_token: bracketed!(content in input), +/// content: content.parse()?, +/// }) +/// } +/// } +/// # +/// # fn main() { +/// # let input = quote! { +/// # #[repr(C, packed)] +/// # }; +/// # syn::parse2::<OuterAttribute>(input).unwrap(); +/// # } +/// ``` +#[macro_export] +#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] +macro_rules! bracketed { + ($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); + } + } + }; +} |