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Diffstat (limited to 'syn/src/token.rs')
| -rw-r--r-- | syn/src/token.rs | 956 |
1 files changed, 956 insertions, 0 deletions
diff --git a/syn/src/token.rs b/syn/src/token.rs new file mode 100644 index 0000000..a9f787a --- /dev/null +++ b/syn/src/token.rs @@ -0,0 +1,956 @@ +//! Tokens representing Rust punctuation, keywords, and delimiters. +//! +//! The type names in this module can be difficult to keep straight, so we +//! prefer to use the [`Token!`] macro instead. This is a type-macro that +//! expands to the token type of the given token. +//! +//! [`Token!`]: ../macro.Token.html +//! +//! # Example +//! +//! The [`ItemStatic`] syntax tree node is defined like this. +//! +//! [`ItemStatic`]: ../struct.ItemStatic.html +//! +//! ``` +//! # use syn::{Attribute, Expr, Ident, Token, Type, Visibility}; +//! # +//! pub struct ItemStatic { +//! pub attrs: Vec<Attribute>, +//! pub vis: Visibility, +//! pub static_token: Token![static], +//! pub mutability: Option<Token![mut]>, +//! pub ident: Ident, +//! pub colon_token: Token![:], +//! pub ty: Box<Type>, +//! pub eq_token: Token![=], +//! pub expr: Box<Expr>, +//! pub semi_token: Token![;], +//! } +//! ``` +//! +//! # Parsing +//! +//! Keywords and punctuation can be parsed through the [`ParseStream::parse`] +//! method. Delimiter tokens are parsed using the [`parenthesized!`], +//! [`bracketed!`] and [`braced!`] macros. +//! +//! [`ParseStream::parse`]: ../parse/struct.ParseBuffer.html#method.parse +//! [`parenthesized!`]: ../macro.parenthesized.html +//! [`bracketed!`]: ../macro.bracketed.html +//! [`braced!`]: ../macro.braced.html +//! +//! ``` +//! use syn::{Attribute, Result}; +//! use syn::parse::{Parse, ParseStream}; +//! # +//! # enum ItemStatic {} +//! +//! // Parse the ItemStatic struct shown above. +//! impl Parse for ItemStatic { +//! fn parse(input: ParseStream) -> Result<Self> { +//! # use syn::ItemStatic; +//! # fn parse(input: ParseStream) -> Result<ItemStatic> { +//! Ok(ItemStatic { +//! attrs: input.call(Attribute::parse_outer)?, +//! vis: input.parse()?, +//! static_token: input.parse()?, +//! mutability: input.parse()?, +//! ident: input.parse()?, +//! colon_token: input.parse()?, +//! ty: input.parse()?, +//! eq_token: input.parse()?, +//! expr: input.parse()?, +//! semi_token: input.parse()?, +//! }) +//! # } +//! # unimplemented!() +//! } +//! } +//! ``` +//! +//! # Other operations +//! +//! Every keyword and punctuation token supports the following operations. +//! +//! - [Peeking] — `input.peek(Token![...])` +//! +//! - [Parsing] — `input.parse::<Token![...]>()?` +//! +//! - [Printing] — `quote!( ... #the_token ... )` +//! +//! - Construction from a [`Span`] — `let the_token = Token` +//! +//! - Field access to its span — `let sp = the_token.span` +//! +//! [Peeking]: ../parse/struct.ParseBuffer.html#method.peek +//! [Parsing]: ../parse/struct.ParseBuffer.html#method.parse +//! [Printing]: https://docs.rs/quote/1.0/quote/trait.ToTokens.html +//! [`Span`]: https://docs.rs/proc-macro2/1.0/proc_macro2/struct.Span.html + +use std; +#[cfg(feature = "extra-traits")] +use std::cmp; +#[cfg(feature = "extra-traits")] +use std::fmt::{self, Debug}; +#[cfg(feature = "extra-traits")] +use std::hash::{Hash, Hasher}; +use std::ops::{Deref, DerefMut}; + +#[cfg(feature = "parsing")] +use proc_macro2::Delimiter; +#[cfg(any(feature = "parsing", feature = "printing"))] +use proc_macro2::Ident; +use proc_macro2::Span; +#[cfg(feature = "printing")] +use proc_macro2::TokenStream; +#[cfg(feature = "printing")] +use quote::{ToTokens, TokenStreamExt}; + +use self::private::WithSpan; +#[cfg(feature = "parsing")] +use crate::buffer::Cursor; +#[cfg(feature = "parsing")] +use crate::error::Result; +#[cfg(any(feature = "full", feature = "derive"))] +#[cfg(feature = "parsing")] +use crate::lifetime::Lifetime; +#[cfg(any(feature = "full", feature = "derive"))] +#[cfg(feature = "parsing")] +use crate::lit::{Lit, LitBool, LitByte, LitByteStr, LitChar, LitFloat, LitInt, LitStr}; +#[cfg(feature = "parsing")] +use crate::lookahead; +#[cfg(feature = "parsing")] +use crate::parse::{Parse, ParseStream}; +use crate::span::IntoSpans; + +/// Marker trait for types that represent single tokens. +/// +/// This trait is sealed and cannot be implemented for types outside of Syn. +#[cfg(feature = "parsing")] +pub trait Token: private::Sealed { + // Not public API. + #[doc(hidden)] + fn peek(cursor: Cursor) -> bool; + + // Not public API. + #[doc(hidden)] + fn display() -> &'static str; +} + +mod private { + use proc_macro2::Span; + + #[cfg(feature = "parsing")] + pub trait Sealed {} + + /// Support writing `token.span` rather than `token.spans[0]` on tokens that + /// hold a single span. + #[repr(C)] + pub struct WithSpan { + pub span: Span, + } +} + +#[cfg(feature = "parsing")] +impl private::Sealed for Ident {} + +#[cfg(any(feature = "full", feature = "derive"))] +#[cfg(feature = "parsing")] +fn peek_impl(cursor: Cursor, peek: fn(ParseStream) -> bool) -> bool { + use crate::parse::Unexpected; + use std::cell::Cell; + use std::rc::Rc; + + let scope = Span::call_site(); + let unexpected = Rc::new(Cell::new(Unexpected::None)); + let buffer = crate::parse::new_parse_buffer(scope, cursor, unexpected); + peek(&buffer) +} + +#[cfg(any(feature = "full", feature = "derive"))] +macro_rules! impl_token { + ($name:ident $display:expr) => { + #[cfg(feature = "parsing")] + impl Token for $name { + fn peek(cursor: Cursor) -> bool { + fn peek(input: ParseStream) -> bool { + <$name as Parse>::parse(input).is_ok() + } + peek_impl(cursor, peek) + } + + fn display() -> &'static str { + $display + } + } + + #[cfg(feature = "parsing")] + impl private::Sealed for $name {} + }; +} + +#[cfg(any(feature = "full", feature = "derive"))] +impl_token!(Lifetime "lifetime"); +#[cfg(any(feature = "full", feature = "derive"))] +impl_token!(Lit "literal"); +#[cfg(any(feature = "full", feature = "derive"))] +impl_token!(LitStr "string literal"); +#[cfg(any(feature = "full", feature = "derive"))] +impl_token!(LitByteStr "byte string literal"); +#[cfg(any(feature = "full", feature = "derive"))] +impl_token!(LitByte "byte literal"); +#[cfg(any(feature = "full", feature = "derive"))] +impl_token!(LitChar "character literal"); +#[cfg(any(feature = "full", feature = "derive"))] +impl_token!(LitInt "integer literal"); +#[cfg(any(feature = "full", feature = "derive"))] +impl_token!(LitFloat "floating point literal"); +#[cfg(any(feature = "full", feature = "derive"))] +impl_token!(LitBool "boolean literal"); + +// Not public API. +#[doc(hidden)] +#[cfg(feature = "parsing")] +pub trait CustomToken { + fn peek(cursor: Cursor) -> bool; + fn display() -> &'static str; +} + +#[cfg(feature = "parsing")] +impl<T: CustomToken> private::Sealed for T {} + +#[cfg(feature = "parsing")] +impl<T: CustomToken> Token for T { + fn peek(cursor: Cursor) -> bool { + <Self as CustomToken>::peek(cursor) + } + + fn display() -> &'static str { + <Self as CustomToken>::display() + } +} + +macro_rules! define_keywords { + ($($token:tt pub struct $name:ident #[$doc:meta])*) => { + $( + #[cfg_attr(feature = "clone-impls", derive(Copy, Clone))] + #[$doc] + /// + /// Don't try to remember the name of this type — use the + /// [`Token!`] macro instead. + /// + /// [`Token!`]: crate::token + pub struct $name { + pub span: Span, + } + + #[doc(hidden)] + #[allow(non_snake_case)] + pub fn $name<S: IntoSpans<[Span; 1]>>(span: S) -> $name { + $name { + span: span.into_spans()[0], + } + } + + impl std::default::Default for $name { + fn default() -> Self { + $name { + span: Span::call_site(), + } + } + } + + #[cfg(feature = "extra-traits")] + impl Debug for $name { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.write_str(stringify!($name)) + } + } + + #[cfg(feature = "extra-traits")] + impl cmp::Eq for $name {} + + #[cfg(feature = "extra-traits")] + impl PartialEq for $name { + fn eq(&self, _other: &$name) -> bool { + true + } + } + + #[cfg(feature = "extra-traits")] + impl Hash for $name { + fn hash<H: Hasher>(&self, _state: &mut H) {} + } + + #[cfg(feature = "printing")] + impl ToTokens for $name { + fn to_tokens(&self, tokens: &mut TokenStream) { + printing::keyword($token, self.span, tokens); + } + } + + #[cfg(feature = "parsing")] + impl Parse for $name { + fn parse(input: ParseStream) -> Result<Self> { + Ok($name { + span: parsing::keyword(input, $token)?, + }) + } + } + + #[cfg(feature = "parsing")] + impl Token for $name { + fn peek(cursor: Cursor) -> bool { + parsing::peek_keyword(cursor, $token) + } + + fn display() -> &'static str { + concat!("`", $token, "`") + } + } + + #[cfg(feature = "parsing")] + impl private::Sealed for $name {} + )* + }; +} + +macro_rules! impl_deref_if_len_is_1 { + ($name:ident/1) => { + impl Deref for $name { + type Target = WithSpan; + + fn deref(&self) -> &Self::Target { + unsafe { &*(self as *const Self as *const WithSpan) } + } + } + + impl DerefMut for $name { + fn deref_mut(&mut self) -> &mut Self::Target { + unsafe { &mut *(self as *mut Self as *mut WithSpan) } + } + } + }; + + ($name:ident/$len:tt) => {}; +} + +macro_rules! define_punctuation_structs { + ($($token:tt pub struct $name:ident/$len:tt #[$doc:meta])*) => { + $( + #[cfg_attr(feature = "clone-impls", derive(Copy, Clone))] + #[repr(C)] + #[$doc] + /// + /// Don't try to remember the name of this type — use the + /// [`Token!`] macro instead. + /// + /// [`Token!`]: crate::token + pub struct $name { + pub spans: [Span; $len], + } + + #[doc(hidden)] + #[allow(non_snake_case)] + pub fn $name<S: IntoSpans<[Span; $len]>>(spans: S) -> $name { + $name { + spans: spans.into_spans(), + } + } + + impl std::default::Default for $name { + fn default() -> Self { + $name { + spans: [Span::call_site(); $len], + } + } + } + + #[cfg(feature = "extra-traits")] + impl Debug for $name { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.write_str(stringify!($name)) + } + } + + #[cfg(feature = "extra-traits")] + impl cmp::Eq for $name {} + + #[cfg(feature = "extra-traits")] + impl PartialEq for $name { + fn eq(&self, _other: &$name) -> bool { + true + } + } + + #[cfg(feature = "extra-traits")] + impl Hash for $name { + fn hash<H: Hasher>(&self, _state: &mut H) {} + } + + impl_deref_if_len_is_1!($name/$len); + )* + }; +} + +macro_rules! define_punctuation { + ($($token:tt pub struct $name:ident/$len:tt #[$doc:meta])*) => { + $( + define_punctuation_structs! { + $token pub struct $name/$len #[$doc] + } + + #[cfg(feature = "printing")] + impl ToTokens for $name { + fn to_tokens(&self, tokens: &mut TokenStream) { + printing::punct($token, &self.spans, tokens); + } + } + + #[cfg(feature = "parsing")] + impl Parse for $name { + fn parse(input: ParseStream) -> Result<Self> { + Ok($name { + spans: parsing::punct(input, $token)?, + }) + } + } + + #[cfg(feature = "parsing")] + impl Token for $name { + fn peek(cursor: Cursor) -> bool { + parsing::peek_punct(cursor, $token) + } + + fn display() -> &'static str { + concat!("`", $token, "`") + } + } + + #[cfg(feature = "parsing")] + impl private::Sealed for $name {} + )* + }; +} + +macro_rules! define_delimiters { + ($($token:tt pub struct $name:ident #[$doc:meta])*) => { + $( + #[cfg_attr(feature = "clone-impls", derive(Copy, Clone))] + #[$doc] + pub struct $name { + pub span: Span, + } + + #[doc(hidden)] + #[allow(non_snake_case)] + pub fn $name<S: IntoSpans<[Span; 1]>>(span: S) -> $name { + $name { + span: span.into_spans()[0], + } + } + + impl std::default::Default for $name { + fn default() -> Self { + $name { + span: Span::call_site(), + } + } + } + + #[cfg(feature = "extra-traits")] + impl Debug for $name { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.write_str(stringify!($name)) + } + } + + #[cfg(feature = "extra-traits")] + impl cmp::Eq for $name {} + + #[cfg(feature = "extra-traits")] + impl PartialEq for $name { + fn eq(&self, _other: &$name) -> bool { + true + } + } + + #[cfg(feature = "extra-traits")] + impl Hash for $name { + fn hash<H: Hasher>(&self, _state: &mut H) {} + } + + impl $name { + #[cfg(feature = "printing")] + pub fn surround<F>(&self, tokens: &mut TokenStream, f: F) + where + F: FnOnce(&mut TokenStream), + { + printing::delim($token, self.span, tokens, f); + } + } + + #[cfg(feature = "parsing")] + impl private::Sealed for $name {} + )* + }; +} + +define_punctuation_structs! { + "_" pub struct Underscore/1 /// `_` +} + +#[cfg(feature = "printing")] +impl ToTokens for Underscore { + fn to_tokens(&self, tokens: &mut TokenStream) { + tokens.append(Ident::new("_", self.span)); + } +} + +#[cfg(feature = "parsing")] +impl Parse for Underscore { + fn parse(input: ParseStream) -> Result<Self> { + input.step(|cursor| { + if let Some((ident, rest)) = cursor.ident() { + if ident == "_" { + return Ok((Underscore(ident.span()), rest)); + } + } + if let Some((punct, rest)) = cursor.punct() { + if punct.as_char() == '_' { + return Ok((Underscore(punct.span()), rest)); + } + } + Err(cursor.error("expected `_`")) + }) + } +} + +#[cfg(feature = "parsing")] +impl Token for Underscore { + fn peek(cursor: Cursor) -> bool { + if let Some((ident, _rest)) = cursor.ident() { + return ident == "_"; + } + if let Some((punct, _rest)) = cursor.punct() { + return punct.as_char() == '_'; + } + false + } + + fn display() -> &'static str { + "`_`" + } +} + +#[cfg(feature = "parsing")] +impl private::Sealed for Underscore {} + +#[cfg(feature = "parsing")] +impl Token for Paren { + fn peek(cursor: Cursor) -> bool { + lookahead::is_delimiter(cursor, Delimiter::Parenthesis) + } + + fn display() -> &'static str { + "parentheses" + } +} + +#[cfg(feature = "parsing")] +impl Token for Brace { + fn peek(cursor: Cursor) -> bool { + lookahead::is_delimiter(cursor, Delimiter::Brace) + } + + fn display() -> &'static str { + "curly braces" + } +} + +#[cfg(feature = "parsing")] +impl Token for Bracket { + fn peek(cursor: Cursor) -> bool { + lookahead::is_delimiter(cursor, Delimiter::Bracket) + } + + fn display() -> &'static str { + "square brackets" + } +} + +#[cfg(feature = "parsing")] +impl Token for Group { + fn peek(cursor: Cursor) -> bool { + lookahead::is_delimiter(cursor, Delimiter::None) + } + + fn display() -> &'static str { + "invisible group" + } +} + +define_keywords! { + "abstract" pub struct Abstract /// `abstract` + "as" pub struct As /// `as` + "async" pub struct Async /// `async` + "auto" pub struct Auto /// `auto` + "await" pub struct Await /// `await` + "become" pub struct Become /// `become` + "box" pub struct Box /// `box` + "break" pub struct Break /// `break` + "const" pub struct Const /// `const` + "continue" pub struct Continue /// `continue` + "crate" pub struct Crate /// `crate` + "default" pub struct Default /// `default` + "do" pub struct Do /// `do` + "dyn" pub struct Dyn /// `dyn` + "else" pub struct Else /// `else` + "enum" pub struct Enum /// `enum` + "extern" pub struct Extern /// `extern` + "final" pub struct Final /// `final` + "fn" pub struct Fn /// `fn` + "for" pub struct For /// `for` + "if" pub struct If /// `if` + "impl" pub struct Impl /// `impl` + "in" pub struct In /// `in` + "let" pub struct Let /// `let` + "loop" pub struct Loop /// `loop` + "macro" pub struct Macro /// `macro` + "match" pub struct Match /// `match` + "mod" pub struct Mod /// `mod` + "move" pub struct Move /// `move` + "mut" pub struct Mut /// `mut` + "override" pub struct Override /// `override` + "priv" pub struct Priv /// `priv` + "pub" pub struct Pub /// `pub` + "ref" pub struct Ref /// `ref` + "return" pub struct Return /// `return` + "Self" pub struct SelfType /// `Self` + "self" pub struct SelfValue /// `self` + "static" pub struct Static /// `static` + "struct" pub struct Struct /// `struct` + "super" pub struct Super /// `super` + "trait" pub struct Trait /// `trait` + "try" pub struct Try /// `try` + "type" pub struct Type /// `type` + "typeof" pub struct Typeof /// `typeof` + "union" pub struct Union /// `union` + "unsafe" pub struct Unsafe /// `unsafe` + "unsized" pub struct Unsized /// `unsized` + "use" pub struct Use /// `use` + "virtual" pub struct Virtual /// `virtual` + "where" pub struct Where /// `where` + "while" pub struct While /// `while` + "yield" pub struct Yield /// `yield` +} + +define_punctuation! { + "+" pub struct Add/1 /// `+` + "+=" pub struct AddEq/2 /// `+=` + "&" pub struct And/1 /// `&` + "&&" pub struct AndAnd/2 /// `&&` + "&=" pub struct AndEq/2 /// `&=` + "@" pub struct At/1 /// `@` + "!" pub struct Bang/1 /// `!` + "^" pub struct Caret/1 /// `^` + "^=" pub struct CaretEq/2 /// `^=` + ":" pub struct Colon/1 /// `:` + "::" pub struct Colon2/2 /// `::` + "," pub struct Comma/1 /// `,` + "/" pub struct Div/1 /// `/` + "/=" pub struct DivEq/2 /// `/=` + "$" pub struct Dollar/1 /// `$` + "." pub struct Dot/1 /// `.` + ".." pub struct Dot2/2 /// `..` + "..." pub struct Dot3/3 /// `...` + "..=" pub struct DotDotEq/3 /// `..=` + "=" pub struct Eq/1 /// `=` + "==" pub struct EqEq/2 /// `==` + ">=" pub struct Ge/2 /// `>=` + ">" pub struct Gt/1 /// `>` + "<=" pub struct Le/2 /// `<=` + "<" pub struct Lt/1 /// `<` + "*=" pub struct MulEq/2 /// `*=` + "!=" pub struct Ne/2 /// `!=` + "|" pub struct Or/1 /// `|` + "|=" pub struct OrEq/2 /// `|=` + "||" pub struct OrOr/2 /// `||` + "#" pub struct Pound/1 /// `#` + "?" pub struct Question/1 /// `?` + "->" pub struct RArrow/2 /// `->` + "<-" pub struct LArrow/2 /// `<-` + "%" pub struct Rem/1 /// `%` + "%=" pub struct RemEq/2 /// `%=` + "=>" pub struct FatArrow/2 /// `=>` + ";" pub struct Semi/1 /// `;` + "<<" pub struct Shl/2 /// `<<` + "<<=" pub struct ShlEq/3 /// `<<=` + ">>" pub struct Shr/2 /// `>>` + ">>=" pub struct ShrEq/3 /// `>>=` + "*" pub struct Star/1 /// `*` + "-" pub struct Sub/1 /// `-` + "-=" pub struct SubEq/2 /// `-=` + "~" pub struct Tilde/1 /// `~` +} + +define_delimiters! { + "{" pub struct Brace /// `{...}` + "[" pub struct Bracket /// `[...]` + "(" pub struct Paren /// `(...)` + " " pub struct Group /// None-delimited group +} + +macro_rules! export_token_macro { + ($($await_rule:tt)*) => { + /// A type-macro that expands to the name of the Rust type representation of a + /// given token. + /// + /// See the [token module] documentation for details and examples. + /// + /// [token module]: crate::token + // Unfortunate duplication due to a rustdoc bug. + // https://github.com/rust-lang/rust/issues/45939 + #[macro_export] + macro_rules! Token { + (abstract) => { $crate::token::Abstract }; + (as) => { $crate::token::As }; + (async) => { $crate::token::Async }; + (auto) => { $crate::token::Auto }; + $($await_rule => { $crate::token::Await };)* + (become) => { $crate::token::Become }; + (box) => { $crate::token::Box }; + (break) => { $crate::token::Break }; + (const) => { $crate::token::Const }; + (continue) => { $crate::token::Continue }; + (crate) => { $crate::token::Crate }; + (default) => { $crate::token::Default }; + (do) => { $crate::token::Do }; + (dyn) => { $crate::token::Dyn }; + (else) => { $crate::token::Else }; + (enum) => { $crate::token::Enum }; + (extern) => { $crate::token::Extern }; + (final) => { $crate::token::Final }; + (fn) => { $crate::token::Fn }; + (for) => { $crate::token::For }; + (if) => { $crate::token::If }; + (impl) => { $crate::token::Impl }; + (in) => { $crate::token::In }; + (let) => { $crate::token::Let }; + (loop) => { $crate::token::Loop }; + (macro) => { $crate::token::Macro }; + (match) => { $crate::token::Match }; + (mod) => { $crate::token::Mod }; + (move) => { $crate::token::Move }; + (mut) => { $crate::token::Mut }; + (override) => { $crate::token::Override }; + (priv) => { $crate::token::Priv }; + (pub) => { $crate::token::Pub }; + (ref) => { $crate::token::Ref }; + (return) => { $crate::token::Return }; + (Self) => { $crate::token::SelfType }; + (self) => { $crate::token::SelfValue }; + (static) => { $crate::token::Static }; + (struct) => { $crate::token::Struct }; + (super) => { $crate::token::Super }; + (trait) => { $crate::token::Trait }; + (try) => { $crate::token::Try }; + (type) => { $crate::token::Type }; + (typeof) => { $crate::token::Typeof }; + (union) => { $crate::token::Union }; + (unsafe) => { $crate::token::Unsafe }; + (unsized) => { $crate::token::Unsized }; + (use) => { $crate::token::Use }; + (virtual) => { $crate::token::Virtual }; + (where) => { $crate::token::Where }; + (while) => { $crate::token::While }; + (yield) => { $crate::token::Yield }; + (+) => { $crate::token::Add }; + (+=) => { $crate::token::AddEq }; + (&) => { $crate::token::And }; + (&&) => { $crate::token::AndAnd }; + (&=) => { $crate::token::AndEq }; + (@) => { $crate::token::At }; + (!) => { $crate::token::Bang }; + (^) => { $crate::token::Caret }; + (^=) => { $crate::token::CaretEq }; + (:) => { $crate::token::Colon }; + (::) => { $crate::token::Colon2 }; + (,) => { $crate::token::Comma }; + (/) => { $crate::token::Div }; + (/=) => { $crate::token::DivEq }; + ($) => { $crate::token::Dollar }; + (.) => { $crate::token::Dot }; + (..) => { $crate::token::Dot2 }; + (...) => { $crate::token::Dot3 }; + (..=) => { $crate::token::DotDotEq }; + (=) => { $crate::token::Eq }; + (==) => { $crate::token::EqEq }; + (>=) => { $crate::token::Ge }; + (>) => { $crate::token::Gt }; + (<=) => { $crate::token::Le }; + (<) => { $crate::token::Lt }; + (*=) => { $crate::token::MulEq }; + (!=) => { $crate::token::Ne }; + (|) => { $crate::token::Or }; + (|=) => { $crate::token::OrEq }; + (||) => { $crate::token::OrOr }; + (#) => { $crate::token::Pound }; + (?) => { $crate::token::Question }; + (->) => { $crate::token::RArrow }; + (<-) => { $crate::token::LArrow }; + (%) => { $crate::token::Rem }; + (%=) => { $crate::token::RemEq }; + (=>) => { $crate::token::FatArrow }; + (;) => { $crate::token::Semi }; + (<<) => { $crate::token::Shl }; + (<<=) => { $crate::token::ShlEq }; + (>>) => { $crate::token::Shr }; + (>>=) => { $crate::token::ShrEq }; + (*) => { $crate::token::Star }; + (-) => { $crate::token::Sub }; + (-=) => { $crate::token::SubEq }; + (~) => { $crate::token::Tilde }; + (_) => { $crate::token::Underscore }; + } + }; +} + +// Old rustc does not permit `await` appearing anywhere in the source file. +// https://github.com/rust-lang/rust/issues/57919 +// We put the Token![await] rule in a place that is not lexed by old rustc. +#[cfg(not(syn_omit_await_from_token_macro))] +include!("await.rs"); // export_token_macro![(await)]; +#[cfg(syn_omit_await_from_token_macro)] +export_token_macro![]; + +// Not public API. +#[doc(hidden)] +#[cfg(feature = "parsing")] +pub mod parsing { + use proc_macro2::{Spacing, Span}; + + use crate::buffer::Cursor; + use crate::error::{Error, Result}; + use crate::parse::ParseStream; + use crate::span::FromSpans; + + pub fn keyword(input: ParseStream, token: &str) -> Result<Span> { + input.step(|cursor| { + if let Some((ident, rest)) = cursor.ident() { + if ident == token { + return Ok((ident.span(), rest)); + } + } + Err(cursor.error(format!("expected `{}`", token))) + }) + } + + pub fn peek_keyword(cursor: Cursor, token: &str) -> bool { + if let Some((ident, _rest)) = cursor.ident() { + ident == token + } else { + false + } + } + + pub fn punct<S: FromSpans>(input: ParseStream, token: &str) -> Result<S> { + let mut spans = [input.span(); 3]; + punct_helper(input, token, &mut spans)?; + Ok(S::from_spans(&spans)) + } + + fn punct_helper(input: ParseStream, token: &str, spans: &mut [Span; 3]) -> Result<()> { + input.step(|cursor| { + let mut cursor = *cursor; + assert!(token.len() <= spans.len()); + + for (i, ch) in token.chars().enumerate() { + match cursor.punct() { + Some((punct, rest)) => { + spans[i] = punct.span(); + if punct.as_char() != ch { + break; + } else if i == token.len() - 1 { + return Ok(((), rest)); + } else if punct.spacing() != Spacing::Joint { + break; + } + cursor = rest; + } + None => break, + } + } + + Err(Error::new(spans[0], format!("expected `{}`", token))) + }) + } + + pub fn peek_punct(mut cursor: Cursor, token: &str) -> bool { + for (i, ch) in token.chars().enumerate() { + match cursor.punct() { + Some((punct, rest)) => { + if punct.as_char() != ch { + break; + } else if i == token.len() - 1 { + return true; + } else if punct.spacing() != Spacing::Joint { + break; + } + cursor = rest; + } + None => break, + } + } + false + } +} + +// Not public API. +#[doc(hidden)] +#[cfg(feature = "printing")] +pub mod printing { + use proc_macro2::{Delimiter, Group, Ident, Punct, Spacing, Span, TokenStream}; + use quote::TokenStreamExt; + + pub fn punct(s: &str, spans: &[Span], tokens: &mut TokenStream) { + assert_eq!(s.len(), spans.len()); + + let mut chars = s.chars(); + let mut spans = spans.iter(); + let ch = chars.next_back().unwrap(); + let span = spans.next_back().unwrap(); + for (ch, span) in chars.zip(spans) { + let mut op = Punct::new(ch, Spacing::Joint); + op.set_span(*span); + tokens.append(op); + } + + let mut op = Punct::new(ch, Spacing::Alone); + op.set_span(*span); + tokens.append(op); + } + + pub fn keyword(s: &str, span: Span, tokens: &mut TokenStream) { + tokens.append(Ident::new(s, span)); + } + + pub fn delim<F>(s: &str, span: Span, tokens: &mut TokenStream, f: F) + where + F: FnOnce(&mut TokenStream), + { + let delim = match s { + "(" => Delimiter::Parenthesis, + "[" => Delimiter::Bracket, + "{" => Delimiter::Brace, + " " => Delimiter::None, + _ => panic!("unknown delimiter: {}", s), + }; + let mut inner = TokenStream::new(); + f(&mut inner); + let mut g = Group::new(delim, inner); + g.set_span(span); + tokens.append(g); + } +} |