use crate::error::Result;
use crate::parse::ParseBuffer;
use crate::token;
use proc_macro2::extra::DelimSpan;
use proc_macro2::Delimiter;
// Not public API.
#[doc(hidden)]
pub struct Parens<'a> {
#[doc(hidden)]
pub token: token::Paren,
#[doc(hidden)]
pub content: ParseBuffer<'a>,
}
// Not public API.
#[doc(hidden)]
pub struct Braces<'a> {
#[doc(hidden)]
pub token: token::Brace,
#[doc(hidden)]
pub content: ParseBuffer<'a>,
}
// Not public API.
#[doc(hidden)]
pub struct Brackets<'a> {
#[doc(hidden)]
pub token: token::Bracket,
#[doc(hidden)]
pub content: ParseBuffer<'a>,
}
// Not public API.
#[cfg(any(feature = "full", feature = "derive"))]
#[doc(hidden)]
pub struct Group<'a> {
#[doc(hidden)]
pub token: token::Group,
#[doc(hidden)]
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.join()),
content,
})
}
fn parse_delimited<'a>(
input: &ParseBuffer<'a>,
delimiter: Delimiter,
) -> Result<(DelimSpan, ParseBuffer<'a>)> {
input.step(|cursor| {
if let Some((content, span, rest)) = cursor.group(delimiter) {
let scope = span.close();
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, Token![,])?,
/// semi_token: input.parse()?,
/// })
/// }
/// }
/// #
/// # fn main() {
/// # let input = quote! {
/// # struct S(A, B);
/// # };
/// # syn::parse2::<TupleStruct>(input).unwrap();
/// # }
/// ```
#[macro_export]
#[cfg_attr(docsrs, 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 $crate::__private::Err(error);
}
}
};
}
/// Parse a set of curly braces and expose their content to subsequent parsers.
///
/// # Example
///
/// ```
/// # use quote::quote;
/// #
/// use syn::{braced, token, Ident, Result, Token, Type};
/// use syn::parse::{Parse, ParseStream};
/// use syn::punctuated::Punctuated;
///
/// // Parse a simplified struct syntax like:
/// //
/// // struct S {
/// // a: A,
/// // b: B,
/// // }
/// struct Struct {
/// struct_token: Token![struct],
/// ident: Ident,
/// brace_token: token::Brace,
/// fields: Punctuated<Field, Token![,]>,
/// }
///
/// struct Field {
/// name: Ident,
/// colon_token: Token![:],
/// ty: Type,
/// }
///
/// impl Parse for Struct {
/// fn parse(input: ParseStream) -> Result<Self> {
/// let content;
/// Ok(Struct {
/// struct_token: input.parse()?,
/// ident: input.parse()?,
/// brace_token: braced!(content in input),
/// fields: content.parse_terminated(Field::parse, Token![,])?,
/// })
/// }
/// }
///
/// impl Parse for Field {
/// fn parse(input: ParseStream) -> Result<Self> {
/// Ok(Field {
/// name: input.parse()?,
/// colon_token: input.parse()?,
/// ty: input.parse()?,
/// })
/// }
/// }
/// #
/// # fn main() {
/// # let input = quote! {
/// # struct S {
/// # a: A,
/// # b: B,
/// # }
/// # };
/// # syn::parse2::<Struct>(input).unwrap();
/// # }
/// ```
#[macro_export]
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
macro_rules! braced {
($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 $crate::__private::Err(error);
}
}
};
}
/// Parse a set of square brackets and expose their content to subsequent
/// parsers.
///
/// # Example
///
/// ```
/// # use quote::quote;
/// #
/// use proc_macro2::TokenStream;
/// use syn::{bracketed, token, Result, Token};
/// use syn::parse::{Parse, ParseStream};
///
/// // Parse an outer attribute like:
/// //
/// // #[repr(C, packed)]
/// struct OuterAttribute {
/// pound_token: Token![#],
/// bracket_token: token::Bracket,
/// content: TokenStream,
/// }
///
/// impl Parse for OuterAttribute {
/// fn parse(input: ParseStream) -> Result<Self> {
/// let content;
/// Ok(OuterAttribute {
/// pound_token: input.parse()?,
/// bracket_token: bracketed!(content in input),
/// content: content.parse()?,
/// })
/// }
/// }
/// #
/// # fn main() {
/// # let input = quote! {
/// # #[repr(C, packed)]
/// # };
/// # syn::parse2::<OuterAttribute>(input).unwrap();
/// # }
/// ```
#[macro_export]
#[cfg_attr(docsrs, doc(cfg(feature = "parsing")))]
macro_rules! bracketed {
($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);
}
}
};
}
