Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1138 insertions, 0 deletions

diff --git a/third_party/rust/syn/src/token.rs b/third_party/rust/syn/src/token.rs
new file mode 100644
index 0000000000..05d8f5601b
--- /dev/null
+++ b/third_party/rust/syn/src/token.rs
@@ -0,0 +1,1138 @@
+//! 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!`]: crate::Token
+//!
+//! # Example
+//!
+//! The [`ItemStatic`] syntax tree node is defined like this.
+//!
+//! [`ItemStatic`]: crate::ItemStatic
+//!
+//! ```
+//! # 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`]: crate::parse::ParseBuffer::parse()
+//! [`parenthesized!`]: crate::parenthesized!
+//! [`bracketed!`]: crate::bracketed!
+//! [`braced!`]: crate::braced!
+//!
+//! ```
+//! 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![...](sp)`
+//!
+//! - Field access to its span — `let sp = the_token.span`
+//!
+//! [Peeking]: crate::parse::ParseBuffer::peek()
+//! [Parsing]: crate::parse::ParseBuffer::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
+
+#[cfg(feature = "parsing")]
+pub(crate) use self::private::CustomToken;
+use self::private::WithSpan;
+#[cfg(feature = "parsing")]
+use crate::buffer::Cursor;
+#[cfg(feature = "parsing")]
+use crate::error::Result;
+#[cfg(feature = "parsing")]
+use crate::lifetime::Lifetime;
+#[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;
+use proc_macro2::extra::DelimSpan;
+use proc_macro2::Span;
+#[cfg(feature = "printing")]
+use proc_macro2::TokenStream;
+#[cfg(any(feature = "parsing", feature = "printing"))]
+use proc_macro2::{Delimiter, Ident};
+#[cfg(feature = "parsing")]
+use proc_macro2::{Literal, Punct, TokenTree};
+#[cfg(feature = "printing")]
+use quote::{ToTokens, TokenStreamExt};
+#[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};
+
+/// 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;
+}
+
+pub(crate) mod private {
+    #[cfg(feature = "parsing")]
+    use crate::buffer::Cursor;
+    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(transparent)]
+    #[allow(unknown_lints, repr_transparent_external_private_fields)] // False positive: https://github.com/rust-lang/rust/issues/78586#issuecomment-1722680482
+    pub struct WithSpan {
+        pub span: Span,
+    }
+
+    // Not public API.
+    #[doc(hidden)]
+    #[cfg(feature = "parsing")]
+    pub trait CustomToken {
+        fn peek(cursor: Cursor) -> bool;
+        fn display() -> &'static str;
+    }
+}
+
+#[cfg(feature = "parsing")]
+impl private::Sealed for Ident {}
+
+#[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)
+}
+
+macro_rules! impl_token {
+    ($display:literal $name:ty) => {
+        #[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 $name {}
+    };
+}
+
+impl_token!("lifetime" Lifetime);
+impl_token!("literal" Lit);
+impl_token!("string literal" LitStr);
+impl_token!("byte string literal" LitByteStr);
+impl_token!("byte literal" LitByte);
+impl_token!("character literal" LitChar);
+impl_token!("integer literal" LitInt);
+impl_token!("floating point literal" LitFloat);
+impl_token!("boolean literal" LitBool);
+impl_token!("group token" proc_macro2::Group);
+
+macro_rules! impl_low_level_token {
+    ($display:literal $ty:ident $get:ident) => {
+        #[cfg(feature = "parsing")]
+        impl Token for $ty {
+            fn peek(cursor: Cursor) -> bool {
+                cursor.$get().is_some()
+            }
+
+            fn display() -> &'static str {
+                $display
+            }
+        }
+
+        #[cfg(feature = "parsing")]
+        impl private::Sealed for $ty {}
+    };
+}
+
+impl_low_level_token!("punctuation token" Punct punct);
+impl_low_level_token!("literal" Literal literal);
+impl_low_level_token!("token" TokenTree token_tree);
+
+#[cfg(feature = "parsing")]
+impl<T: CustomToken> private::Sealed for T {}
+
+#[cfg(feature = "parsing")]
+impl<T: CustomToken> Token for T {
+    fn peek(cursor: Cursor) -> bool {
+        <Self as CustomToken>::peek(cursor)
+    }
+
+    fn display() -> &'static str {
+        <Self as CustomToken>::display()
+    }
+}
+
+macro_rules! define_keywords {
+    ($($token:literal pub struct $name:ident)*) => {
+        $(
+            #[doc = concat!('`', $token, '`')]
+            ///
+            /// Don't try to remember the name of this type &mdash; 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>>(span: S) -> $name {
+                $name {
+                    span: span.into_spans(),
+                }
+            }
+
+            impl std::default::Default for $name {
+                fn default() -> Self {
+                    $name {
+                        span: Span::call_site(),
+                    }
+                }
+            }
+
+            #[cfg(feature = "clone-impls")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+            impl Copy for $name {}
+
+            #[cfg(feature = "clone-impls")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+            impl Clone for $name {
+                fn clone(&self) -> Self {
+                    *self
+                }
+            }
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(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")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl cmp::Eq for $name {}
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl PartialEq for $name {
+                fn eq(&self, _other: &$name) -> bool {
+                    true
+                }
+            }
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl Hash for $name {
+                fn hash<H: Hasher>(&self, _state: &mut H) {}
+            }
+
+            #[cfg(feature = "printing")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+            impl ToTokens for $name {
+                fn to_tokens(&self, tokens: &mut TokenStream) {
+                    printing::keyword($token, self.span, tokens);
+                }
+            }
+
+            #[cfg(feature = "parsing")]
+            #[cfg_attr(doc_cfg, doc(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).cast::<WithSpan>() }
+            }
+        }
+
+        impl DerefMut for $name {
+            fn deref_mut(&mut self) -> &mut Self::Target {
+                unsafe { &mut *(self as *mut Self).cast::<WithSpan>() }
+            }
+        }
+    };
+
+    ($name:ident/$len:literal) => {};
+}
+
+macro_rules! define_punctuation_structs {
+    ($($token:literal pub struct $name:ident/$len:tt #[doc = $usage:literal])*) => {
+        $(
+            #[cfg_attr(not(doc), repr(transparent))]
+            #[allow(unknown_lints, repr_transparent_external_private_fields)] // False positive: https://github.com/rust-lang/rust/issues/78586#issuecomment-1722680482
+            #[doc = concat!('`', $token, '`')]
+            ///
+            /// Usage:
+            #[doc = concat!($usage, '.')]
+            ///
+            /// Don't try to remember the name of this type &mdash; 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 = "clone-impls")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+            impl Copy for $name {}
+
+            #[cfg(feature = "clone-impls")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+            impl Clone for $name {
+                fn clone(&self) -> Self {
+                    *self
+                }
+            }
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(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")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl cmp::Eq for $name {}
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl PartialEq for $name {
+                fn eq(&self, _other: &$name) -> bool {
+                    true
+                }
+            }
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(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:literal pub struct $name:ident/$len:tt #[doc = $usage:literal])*) => {
+        $(
+            define_punctuation_structs! {
+                $token pub struct $name/$len #[doc = $usage]
+            }
+
+            #[cfg(feature = "printing")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+            impl ToTokens for $name {
+                fn to_tokens(&self, tokens: &mut TokenStream) {
+                    printing::punct($token, &self.spans, tokens);
+                }
+            }
+
+            #[cfg(feature = "parsing")]
+            #[cfg_attr(doc_cfg, doc(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 $name {}
+        )*
+    };
+}
+
+macro_rules! define_delimiters {
+    ($($delim:ident pub struct $name:ident #[$doc:meta])*) => {
+        $(
+            #[$doc]
+            pub struct $name {
+                pub span: DelimSpan,
+            }
+
+            #[doc(hidden)]
+            #[allow(non_snake_case)]
+            pub fn $name<S: IntoSpans<DelimSpan>>(span: S) -> $name {
+                $name {
+                    span: span.into_spans(),
+                }
+            }
+
+            impl std::default::Default for $name {
+                fn default() -> Self {
+                    $name(Span::call_site())
+                }
+            }
+
+            #[cfg(feature = "clone-impls")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+            impl Copy for $name {}
+
+            #[cfg(feature = "clone-impls")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+            impl Clone for $name {
+                fn clone(&self) -> Self {
+                    *self
+                }
+            }
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(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")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl cmp::Eq for $name {}
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl PartialEq for $name {
+                fn eq(&self, _other: &$name) -> bool {
+                    true
+                }
+            }
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl Hash for $name {
+                fn hash<H: Hasher>(&self, _state: &mut H) {}
+            }
+
+            impl $name {
+                #[cfg(feature = "printing")]
+                pub fn surround<F>(&self, tokens: &mut TokenStream, f: F)
+                where
+                    F: FnOnce(&mut TokenStream),
+                {
+                    let mut inner = TokenStream::new();
+                    f(&mut inner);
+                    printing::delim(Delimiter::$delim, self.span.join(), tokens, inner);
+                }
+            }
+
+            #[cfg(feature = "parsing")]
+            impl private::Sealed for $name {}
+        )*
+    };
+}
+
+define_punctuation_structs! {
+    "_" pub struct Underscore/1 /// wildcard patterns, inferred types, unnamed items in constants, extern crates, use declarations, and destructuring assignment
+}
+
+#[cfg(feature = "printing")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+impl ToTokens for Underscore {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        tokens.append(Ident::new("_", self.span));
+    }
+}
+
+#[cfg(feature = "parsing")]
+#[cfg_attr(doc_cfg, doc(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 {}
+
+/// None-delimited group
+pub struct Group {
+    pub span: Span,
+}
+
+#[doc(hidden)]
+#[allow(non_snake_case)]
+pub fn Group<S: IntoSpans<Span>>(span: S) -> Group {
+    Group {
+        span: span.into_spans(),
+    }
+}
+
+impl std::default::Default for Group {
+    fn default() -> Self {
+        Group {
+            span: Span::call_site(),
+        }
+    }
+}
+
+#[cfg(feature = "clone-impls")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Copy for Group {}
+
+#[cfg(feature = "clone-impls")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for Group {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for Group {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("Group")
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl cmp::Eq for Group {}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for Group {
+    fn eq(&self, _other: &Group) -> bool {
+        true
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for Group {
+    fn hash<H: Hasher>(&self, _state: &mut H) {}
+}
+
+impl Group {
+    #[cfg(feature = "printing")]
+    pub fn surround<F>(&self, tokens: &mut TokenStream, f: F)
+    where
+        F: FnOnce(&mut TokenStream),
+    {
+        let mut inner = TokenStream::new();
+        f(&mut inner);
+        printing::delim(Delimiter::None, self.span, tokens, inner);
+    }
+}
+
+#[cfg(feature = "parsing")]
+impl private::Sealed for Group {}
+
+#[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
+    "as"          pub struct As
+    "async"       pub struct Async
+    "auto"        pub struct Auto
+    "await"       pub struct Await
+    "become"      pub struct Become
+    "box"         pub struct Box
+    "break"       pub struct Break
+    "const"       pub struct Const
+    "continue"    pub struct Continue
+    "crate"       pub struct Crate
+    "default"     pub struct Default
+    "do"          pub struct Do
+    "dyn"         pub struct Dyn
+    "else"        pub struct Else
+    "enum"        pub struct Enum
+    "extern"      pub struct Extern
+    "final"       pub struct Final
+    "fn"          pub struct Fn
+    "for"         pub struct For
+    "if"          pub struct If
+    "impl"        pub struct Impl
+    "in"          pub struct In
+    "let"         pub struct Let
+    "loop"        pub struct Loop
+    "macro"       pub struct Macro
+    "match"       pub struct Match
+    "mod"         pub struct Mod
+    "move"        pub struct Move
+    "mut"         pub struct Mut
+    "override"    pub struct Override
+    "priv"        pub struct Priv
+    "pub"         pub struct Pub
+    "ref"         pub struct Ref
+    "return"      pub struct Return
+    "Self"        pub struct SelfType
+    "self"        pub struct SelfValue
+    "static"      pub struct Static
+    "struct"      pub struct Struct
+    "super"       pub struct Super
+    "trait"       pub struct Trait
+    "try"         pub struct Try
+    "type"        pub struct Type
+    "typeof"      pub struct Typeof
+    "union"       pub struct Union
+    "unsafe"      pub struct Unsafe
+    "unsized"     pub struct Unsized
+    "use"         pub struct Use
+    "virtual"     pub struct Virtual
+    "where"       pub struct Where
+    "while"       pub struct While
+    "yield"       pub struct Yield
+}
+
+define_punctuation! {
+    "&"           pub struct And/1        /// bitwise and logical AND, borrow, references, reference patterns
+    "&&"          pub struct AndAnd/2     /// lazy AND, borrow, references, reference patterns
+    "&="          pub struct AndEq/2      /// bitwise AND assignment
+    "@"           pub struct At/1         /// subpattern binding
+    "^"           pub struct Caret/1      /// bitwise and logical XOR
+    "^="          pub struct CaretEq/2    /// bitwise XOR assignment
+    ":"           pub struct Colon/1      /// various separators
+    ","           pub struct Comma/1      /// various separators
+    "$"           pub struct Dollar/1     /// macros
+    "."           pub struct Dot/1        /// field access, tuple index
+    ".."          pub struct DotDot/2     /// range, struct expressions, patterns, range patterns
+    "..."         pub struct DotDotDot/3  /// variadic functions, range patterns
+    "..="         pub struct DotDotEq/3   /// inclusive range, range patterns
+    "="           pub struct Eq/1         /// assignment, attributes, various type definitions
+    "=="          pub struct EqEq/2       /// equal
+    "=>"          pub struct FatArrow/2   /// match arms, macros
+    ">="          pub struct Ge/2         /// greater than or equal to, generics
+    ">"           pub struct Gt/1         /// greater than, generics, paths
+    "<-"          pub struct LArrow/2     /// unused
+    "<="          pub struct Le/2         /// less than or equal to
+    "<"           pub struct Lt/1         /// less than, generics, paths
+    "-"           pub struct Minus/1      /// subtraction, negation
+    "-="          pub struct MinusEq/2    /// subtraction assignment
+    "!="          pub struct Ne/2         /// not equal
+    "!"           pub struct Not/1        /// bitwise and logical NOT, macro calls, inner attributes, never type, negative impls
+    "|"           pub struct Or/1         /// bitwise and logical OR, closures, patterns in match, if let, and while let
+    "|="          pub struct OrEq/2       /// bitwise OR assignment
+    "||"          pub struct OrOr/2       /// lazy OR, closures
+    "::"          pub struct PathSep/2    /// path separator
+    "%"           pub struct Percent/1    /// remainder
+    "%="          pub struct PercentEq/2  /// remainder assignment
+    "+"           pub struct Plus/1       /// addition, trait bounds, macro Kleene matcher
+    "+="          pub struct PlusEq/2     /// addition assignment
+    "#"           pub struct Pound/1      /// attributes
+    "?"           pub struct Question/1   /// question mark operator, questionably sized, macro Kleene matcher
+    "->"          pub struct RArrow/2     /// function return type, closure return type, function pointer type
+    ";"           pub struct Semi/1       /// terminator for various items and statements, array types
+    "<<"          pub struct Shl/2        /// shift left, nested generics
+    "<<="         pub struct ShlEq/3      /// shift left assignment
+    ">>"          pub struct Shr/2        /// shift right, nested generics
+    ">>="         pub struct ShrEq/3      /// shift right assignment, nested generics
+    "/"           pub struct Slash/1      /// division
+    "/="          pub struct SlashEq/2    /// division assignment
+    "*"           pub struct Star/1       /// multiplication, dereference, raw pointers, macro Kleene matcher, use wildcards
+    "*="          pub struct StarEq/2     /// multiplication assignment
+    "~"           pub struct Tilde/1      /// unused since before Rust 1.0
+}
+
+define_delimiters! {
+    Brace         pub struct Brace        /// `{`&hellip;`}`
+    Bracket       pub struct Bracket      /// `[`&hellip;`]`
+    Parenthesis   pub struct Paren        /// `(`&hellip;`)`
+}
+
+/// A type-macro that expands to the name of the Rust type representation of a
+/// given token.
+///
+/// As a type, `Token!` is commonly used in the type of struct fields, the type
+/// of a `let` statement, or in turbofish for a `parse` function.
+///
+/// ```
+/// use syn::{Ident, Token};
+/// use syn::parse::{Parse, ParseStream, Result};
+///
+/// // `struct Foo;`
+/// pub struct UnitStruct {
+///     struct_token: Token![struct],
+///     ident: Ident,
+///     semi_token: Token![;],
+/// }
+///
+/// impl Parse for UnitStruct {
+///     fn parse(input: ParseStream) -> Result<Self> {
+///         let struct_token: Token![struct] = input.parse()?;
+///         let ident: Ident = input.parse()?;
+///         let semi_token = input.parse::<Token![;]>()?;
+///         Ok(UnitStruct { struct_token, ident, semi_token })
+///     }
+/// }
+/// ```
+///
+/// As an expression, `Token!` is used for peeking tokens or instantiating
+/// tokens from a span.
+///
+/// ```
+/// # use syn::{Ident, Token};
+/// # use syn::parse::{Parse, ParseStream, Result};
+/// #
+/// # struct UnitStruct {
+/// #     struct_token: Token![struct],
+/// #     ident: Ident,
+/// #     semi_token: Token![;],
+/// # }
+/// #
+/// # impl Parse for UnitStruct {
+/// #     fn parse(input: ParseStream) -> Result<Self> {
+/// #         unimplemented!()
+/// #     }
+/// # }
+/// #
+/// fn make_unit_struct(name: Ident) -> UnitStruct {
+///     let span = name.span();
+///     UnitStruct {
+///         struct_token: Token![struct](span),
+///         ident: name,
+///         semi_token: Token![;](span),
+///     }
+/// }
+///
+/// # fn parse(input: ParseStream) -> Result<()> {
+/// if input.peek(Token![struct]) {
+///     let unit_struct: UnitStruct = input.parse()?;
+///     /* ... */
+/// }
+/// # Ok(())
+/// # }
+/// ```
+///
+/// See the [token module] documentation for details and examples.
+///
+/// [token module]: crate::token
+#[macro_export]
+macro_rules! Token {
+    [abstract]    => { $crate::token::Abstract };
+    [as]          => { $crate::token::As };
+    [async]       => { $crate::token::Async };
+    [auto]        => { $crate::token::Auto };
+    [await]       => { $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::And };
+    [&&]          => { $crate::token::AndAnd };
+    [&=]          => { $crate::token::AndEq };
+    [@]           => { $crate::token::At };
+    [^]           => { $crate::token::Caret };
+    [^=]          => { $crate::token::CaretEq };
+    [:]           => { $crate::token::Colon };
+    [,]           => { $crate::token::Comma };
+    [$]           => { $crate::token::Dollar };
+    [.]           => { $crate::token::Dot };
+    [..]          => { $crate::token::DotDot };
+    [...]         => { $crate::token::DotDotDot };
+    [..=]         => { $crate::token::DotDotEq };
+    [=]           => { $crate::token::Eq };
+    [==]          => { $crate::token::EqEq };
+    [=>]          => { $crate::token::FatArrow };
+    [>=]          => { $crate::token::Ge };
+    [>]           => { $crate::token::Gt };
+    [<-]          => { $crate::token::LArrow };
+    [<=]          => { $crate::token::Le };
+    [<]           => { $crate::token::Lt };
+    [-]           => { $crate::token::Minus };
+    [-=]          => { $crate::token::MinusEq };
+    [!=]          => { $crate::token::Ne };
+    [!]           => { $crate::token::Not };
+    [|]           => { $crate::token::Or };
+    [|=]          => { $crate::token::OrEq };
+    [||]          => { $crate::token::OrOr };
+    [::]          => { $crate::token::PathSep };
+    [%]           => { $crate::token::Percent };
+    [%=]          => { $crate::token::PercentEq };
+    [+]           => { $crate::token::Plus };
+    [+=]          => { $crate::token::PlusEq };
+    [#]           => { $crate::token::Pound };
+    [?]           => { $crate::token::Question };
+    [->]          => { $crate::token::RArrow };
+    [;]           => { $crate::token::Semi };
+    [<<]          => { $crate::token::Shl };
+    [<<=]         => { $crate::token::ShlEq };
+    [>>]          => { $crate::token::Shr };
+    [>>=]         => { $crate::token::ShrEq };
+    [/]           => { $crate::token::Slash };
+    [/=]          => { $crate::token::SlashEq };
+    [*]           => { $crate::token::Star };
+    [*=]          => { $crate::token::StarEq };
+    [~]           => { $crate::token::Tilde };
+    [_]           => { $crate::token::Underscore };
+}
+
+// Not public API.
+#[doc(hidden)]
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::buffer::Cursor;
+    use crate::error::{Error, Result};
+    use crate::parse::ParseStream;
+    use proc_macro2::{Spacing, Span};
+
+    pub(crate) 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(crate) fn peek_keyword(cursor: Cursor, token: &str) -> bool {
+        if let Some((ident, _rest)) = cursor.ident() {
+            ident == token
+        } else {
+            false
+        }
+    }
+
+    #[doc(hidden)]
+    pub fn punct<const N: usize>(input: ParseStream, token: &str) -> Result<[Span; N]> {
+        let mut spans = [input.span(); N];
+        punct_helper(input, token, &mut spans)?;
+        Ok(spans)
+    }
+
+    fn punct_helper(input: ParseStream, token: &str, spans: &mut [Span]) -> Result<()> {
+        input.step(|cursor| {
+            let mut cursor = *cursor;
+            assert_eq!(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)))
+        })
+    }
+
+    #[doc(hidden)]
+    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(crate) mod printing {
+    use proc_macro2::{Delimiter, Group, Ident, Punct, Spacing, Span, TokenStream};
+    use quote::TokenStreamExt;
+
+    #[doc(hidden)]
+    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(crate) fn keyword(s: &str, span: Span, tokens: &mut TokenStream) {
+        tokens.append(Ident::new(s, span));
+    }
+
+    pub(crate) fn delim(
+        delim: Delimiter,
+        span: Span,
+        tokens: &mut TokenStream,
+        inner: TokenStream,
+    ) {
+        let mut g = Group::new(delim, inner);
+        g.set_span(span);
+        tokens.append(g);
+    }
+}