From 5e20a29b4fdc8a2d442d1093681b396dcb4b816b Mon Sep 17 00:00:00 2001 From: Robin Krahl Date: Tue, 7 Jan 2020 11:18:04 +0000 Subject: Add structopt dependency in version 0.3.7 This patch series replaces argparse with structopt in the argument handling code. As a first step, we need structopt as a dependency. Import subrepo structopt/:structopt at efbdda4753592e27bc430fb01f7b9650b2f3174d Import subrepo bitflags/:bitflags at 30668016aca6bd3b02c766e8347e0b4080d4c296 Import subrepo clap/:clap at 784524f7eb193e35f81082cc69454c8c21b948f7 Import subrepo heck/:heck at 093d56fbf001e1506e56dbfa38631d99b1066df1 Import subrepo proc-macro-error/:proc-macro-error at 6c4cfe79a622c5de8ae68557993542be46eacae2 Import subrepo proc-macro2/:proc-macro2 at d5d48eddca4566e5438e8a2cbed4a74e049544de Import subrepo quote/:quote at 727436c6c137b20f0f34dde5d8fda2679b9747ad Import subrepo rustversion/:rustversion at 0c5663313516263059ce9059ef81fc7a1cf655ca Import subrepo syn-mid/:syn-mid at 5d3d85414a9e6674e1857ec22a87b96e04a6851a Import subrepo syn/:syn at e87c27e87f6f4ef8919d0372bdb056d53ef0d8f3 Import subrepo textwrap/:textwrap at abcd618beae3f74841032aa5b53c1086b0a57ca2 Import subrepo unicode-segmentation/:unicode-segmentation at 637c9874c4fe0c205ff27787faf150a40295c6c3 Import subrepo unicode-width/:unicode-width at 3033826f8bf05e82724140a981d5941e48fce393 Import subrepo unicode-xid/:unicode-xid at 4baae9fffb156ba229665b972a9cd5991787ceb7 --- syn/src/attr.rs | 682 ++++++++ syn/src/await.rs | 2 + syn/src/bigint.rs | 66 + syn/src/buffer.rs | 382 +++++ syn/src/custom_keyword.rs | 252 +++ syn/src/custom_punctuation.rs | 309 ++++ syn/src/data.rs | 456 +++++ syn/src/derive.rs | 273 +++ syn/src/discouraged.rs | 195 +++ syn/src/error.rs | 357 ++++ syn/src/export.rs | 35 + syn/src/expr.rs | 3236 +++++++++++++++++++++++++++++++++++ syn/src/ext.rs | 135 ++ syn/src/file.rs | 113 ++ syn/src/gen/fold.rs | 3236 +++++++++++++++++++++++++++++++++++ syn/src/gen/visit.rs | 3792 ++++++++++++++++++++++++++++++++++++++++ syn/src/gen/visit_mut.rs | 3798 +++++++++++++++++++++++++++++++++++++++++ syn/src/gen_helper.rs | 154 ++ syn/src/generics.rs | 1152 +++++++++++++ syn/src/group.rs | 280 +++ syn/src/ident.rs | 101 ++ syn/src/item.rs | 3104 +++++++++++++++++++++++++++++++++ syn/src/keyword.rs | 0 syn/src/lib.rs | 947 ++++++++++ syn/src/lifetime.rs | 140 ++ syn/src/lit.rs | 1382 +++++++++++++++ syn/src/lookahead.rs | 168 ++ syn/src/mac.rs | 239 +++ syn/src/macros.rs | 191 +++ syn/src/op.rs | 231 +++ syn/src/parse.rs | 1222 +++++++++++++ syn/src/parse_macro_input.rs | 110 ++ syn/src/parse_quote.rs | 131 ++ syn/src/pat.rs | 903 ++++++++++ syn/src/path.rs | 744 ++++++++ syn/src/print.rs | 16 + syn/src/punctuated.rs | 918 ++++++++++ syn/src/sealed.rs | 4 + syn/src/span.rs | 67 + syn/src/spanned.rs | 114 ++ syn/src/stmt.rs | 333 ++++ syn/src/thread.rs | 41 + syn/src/token.rs | 956 +++++++++++ syn/src/tt.rs | 108 ++ syn/src/ty.rs | 1178 +++++++++++++ 45 files changed, 32253 insertions(+) create mode 100644 syn/src/attr.rs create mode 100644 syn/src/await.rs create mode 100644 syn/src/bigint.rs create mode 100644 syn/src/buffer.rs create mode 100644 syn/src/custom_keyword.rs create mode 100644 syn/src/custom_punctuation.rs create mode 100644 syn/src/data.rs create mode 100644 syn/src/derive.rs create mode 100644 syn/src/discouraged.rs create mode 100644 syn/src/error.rs create mode 100644 syn/src/export.rs create mode 100644 syn/src/expr.rs create mode 100644 syn/src/ext.rs create mode 100644 syn/src/file.rs create mode 100644 syn/src/gen/fold.rs create mode 100644 syn/src/gen/visit.rs create mode 100644 syn/src/gen/visit_mut.rs create mode 100644 syn/src/gen_helper.rs create mode 100644 syn/src/generics.rs create mode 100644 syn/src/group.rs create mode 100644 syn/src/ident.rs create mode 100644 syn/src/item.rs create mode 100644 syn/src/keyword.rs create mode 100644 syn/src/lib.rs create mode 100644 syn/src/lifetime.rs create mode 100644 syn/src/lit.rs create mode 100644 syn/src/lookahead.rs create mode 100644 syn/src/mac.rs create mode 100644 syn/src/macros.rs create mode 100644 syn/src/op.rs create mode 100644 syn/src/parse.rs create mode 100644 syn/src/parse_macro_input.rs create mode 100644 syn/src/parse_quote.rs create mode 100644 syn/src/pat.rs create mode 100644 syn/src/path.rs create mode 100644 syn/src/print.rs create mode 100644 syn/src/punctuated.rs create mode 100644 syn/src/sealed.rs create mode 100644 syn/src/span.rs create mode 100644 syn/src/spanned.rs create mode 100644 syn/src/stmt.rs create mode 100644 syn/src/thread.rs create mode 100644 syn/src/token.rs create mode 100644 syn/src/tt.rs create mode 100644 syn/src/ty.rs (limited to 'syn/src') diff --git a/syn/src/attr.rs b/syn/src/attr.rs new file mode 100644 index 0000000..a8e16ea --- /dev/null +++ b/syn/src/attr.rs @@ -0,0 +1,682 @@ +use super::*; +use crate::punctuated::Punctuated; + +use std::iter; + +use proc_macro2::TokenStream; + +#[cfg(feature = "parsing")] +use crate::parse::{Parse, ParseBuffer, ParseStream, Parser, Result}; +#[cfg(feature = "parsing")] +use crate::punctuated::Pair; +#[cfg(feature = "extra-traits")] +use crate::tt::TokenStreamHelper; +#[cfg(feature = "extra-traits")] +use std::hash::{Hash, Hasher}; + +ast_struct! { + /// An attribute like `#[repr(transparent)]`. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + /// + ///
+ /// + /// # Syntax + /// + /// Rust has six types of attributes. + /// + /// - Outer attributes like `#[repr(transparent)]`. These appear outside or + /// in front of the item they describe. + /// - Inner attributes like `#![feature(proc_macro)]`. These appear inside + /// of the item they describe, usually a module. + /// - Outer doc comments like `/// # Example`. + /// - Inner doc comments like `//! Please file an issue`. + /// - Outer block comments `/** # Example */`. + /// - Inner block comments `/*! Please file an issue */`. + /// + /// The `style` field of type `AttrStyle` distinguishes whether an attribute + /// is outer or inner. Doc comments and block comments are promoted to + /// attributes, as this is how they are processed by the compiler and by + /// `macro_rules!` macros. + /// + /// The `path` field gives the possibly colon-delimited path against which + /// the attribute is resolved. It is equal to `"doc"` for desugared doc + /// comments. The `tokens` field contains the rest of the attribute body as + /// tokens. + /// + /// ```text + /// #[derive(Copy)] #[crate::precondition x < 5] + /// ^^^^^^~~~~~~ ^^^^^^^^^^^^^^^^^^^ ~~~~~ + /// path tokens path tokens + /// ``` + /// + ///
+ /// + /// # Parsing from tokens to Attribute + /// + /// This type does not implement the [`Parse`] trait and thus cannot be + /// parsed directly by [`ParseStream::parse`]. Instead use + /// [`ParseStream::call`] with one of the two parser functions + /// [`Attribute::parse_outer`] or [`Attribute::parse_inner`] depending on + /// which you intend to parse. + /// + /// [`Parse`]: parse::Parse + /// [`ParseStream::parse`]: parse::ParseBuffer::parse + /// [`ParseStream::call`]: parse::ParseBuffer::call + /// + /// ``` + /// use syn::{Attribute, Ident, Result, Token}; + /// use syn::parse::{Parse, ParseStream}; + /// + /// // Parses a unit struct with attributes. + /// // + /// // #[path = "s.tmpl"] + /// // struct S; + /// struct UnitStruct { + /// attrs: Vec, + /// struct_token: Token![struct], + /// name: Ident, + /// semi_token: Token![;], + /// } + /// + /// impl Parse for UnitStruct { + /// fn parse(input: ParseStream) -> Result { + /// Ok(UnitStruct { + /// attrs: input.call(Attribute::parse_outer)?, + /// struct_token: input.parse()?, + /// name: input.parse()?, + /// semi_token: input.parse()?, + /// }) + /// } + /// } + /// ``` + /// + ///


+ /// + /// # Parsing from Attribute to structured arguments + /// + /// The grammar of attributes in Rust is very flexible, which makes the + /// syntax tree not that useful on its own. In particular, arguments of the + /// attribute are held in an arbitrary `tokens: TokenStream`. Macros are + /// expected to check the `path` of the attribute, decide whether they + /// recognize it, and then parse the remaining tokens according to whatever + /// grammar they wish to require for that kind of attribute. + /// + /// If the attribute you are parsing is expected to conform to the + /// conventional structured form of attribute, use [`parse_meta()`] to + /// obtain that structured representation. If the attribute follows some + /// other grammar of its own, use [`parse_args()`] to parse that into the + /// expected data structure. + /// + /// [`parse_meta()`]: Attribute::parse_meta + /// [`parse_args()`]: Attribute::parse_args + /// + ///


+ /// + /// # Doc comments + /// + /// The compiler transforms doc comments, such as `/// comment` and `/*! + /// comment */`, into attributes before macros are expanded. Each comment is + /// expanded into an attribute of the form `#[doc = r"comment"]`. + /// + /// As an example, the following `mod` items are expanded identically: + /// + /// ``` + /// # use syn::{ItemMod, parse_quote}; + /// let doc: ItemMod = parse_quote! { + /// /// Single line doc comments + /// /// We write so many! + /// /** + /// * Multi-line comments... + /// * May span many lines + /// */ + /// mod example { + /// //! Of course, they can be inner too + /// /*! And fit in a single line */ + /// } + /// }; + /// let attr: ItemMod = parse_quote! { + /// #[doc = r" Single line doc comments"] + /// #[doc = r" We write so many!"] + /// #[doc = r" Multi-line comments... + /// May span many lines"] + /// mod example { + /// #![doc = r" Of course, they can be inner too"] + /// #![doc = r" And fit in a single line "] + /// } + /// }; + /// assert_eq!(doc, attr); + /// ``` + pub struct Attribute #manual_extra_traits { + pub pound_token: Token![#], + pub style: AttrStyle, + pub bracket_token: token::Bracket, + pub path: Path, + pub tokens: TokenStream, + } +} + +#[cfg(feature = "extra-traits")] +impl Eq for Attribute {} + +#[cfg(feature = "extra-traits")] +impl PartialEq for Attribute { + fn eq(&self, other: &Self) -> bool { + self.style == other.style + && self.pound_token == other.pound_token + && self.bracket_token == other.bracket_token + && self.path == other.path + && TokenStreamHelper(&self.tokens) == TokenStreamHelper(&other.tokens) + } +} + +#[cfg(feature = "extra-traits")] +impl Hash for Attribute { + fn hash(&self, state: &mut H) + where + H: Hasher, + { + self.style.hash(state); + self.pound_token.hash(state); + self.bracket_token.hash(state); + self.path.hash(state); + TokenStreamHelper(&self.tokens).hash(state); + } +} + +impl Attribute { + /// Parses the content of the attribute, consisting of the path and tokens, + /// as a [`Meta`] if possible. + /// + /// *This function is available if Syn is built with the `"parsing"` + /// feature.* + #[cfg(feature = "parsing")] + pub fn parse_meta(&self) -> Result { + fn clone_ident_segment(segment: &PathSegment) -> PathSegment { + PathSegment { + ident: segment.ident.clone(), + arguments: PathArguments::None, + } + } + + let path = Path { + leading_colon: self + .path + .leading_colon + .as_ref() + .map(|colon| Token![::](colon.spans)), + segments: self + .path + .segments + .pairs() + .map(|pair| match pair { + Pair::Punctuated(seg, punct) => { + Pair::Punctuated(clone_ident_segment(seg), Token![::](punct.spans)) + } + Pair::End(seg) => Pair::End(clone_ident_segment(seg)), + }) + .collect(), + }; + + let parser = |input: ParseStream| parsing::parse_meta_after_path(path, input); + parse::Parser::parse2(parser, self.tokens.clone()) + } + + /// Parse the arguments to the attribute as a syntax tree. + /// + /// This is similar to `syn::parse2::(attr.tokens)` except that: + /// + /// - the surrounding delimiters are *not* included in the input to the + /// parser; and + /// - the error message has a more useful span when `tokens` is empty. + /// + /// ```text + /// #[my_attr(value < 5)] + /// ^^^^^^^^^ what gets parsed + /// ``` + /// + /// *This function is available if Syn is built with the `"parsing"` + /// feature.* + #[cfg(feature = "parsing")] + pub fn parse_args(&self) -> Result { + self.parse_args_with(T::parse) + } + + /// Parse the arguments to the attribute using the given parser. + /// + /// *This function is available if Syn is built with the `"parsing"` + /// feature.* + #[cfg(feature = "parsing")] + pub fn parse_args_with(&self, parser: F) -> Result { + let parser = |input: ParseStream| { + let args = enter_args(self, input)?; + parse::parse_stream(parser, &args) + }; + parser.parse2(self.tokens.clone()) + } + + /// Parses zero or more outer attributes from the stream. + /// + /// *This function is available if Syn is built with the `"parsing"` + /// feature.* + #[cfg(feature = "parsing")] + pub fn parse_outer(input: ParseStream) -> Result> { + let mut attrs = Vec::new(); + while input.peek(Token![#]) { + attrs.push(input.call(parsing::single_parse_outer)?); + } + Ok(attrs) + } + + /// Parses zero or more inner attributes from the stream. + /// + /// *This function is available if Syn is built with the `"parsing"` + /// feature.* + #[cfg(feature = "parsing")] + pub fn parse_inner(input: ParseStream) -> Result> { + let mut attrs = Vec::new(); + while input.peek(Token![#]) && input.peek2(Token![!]) { + attrs.push(input.call(parsing::single_parse_inner)?); + } + Ok(attrs) + } +} + +#[cfg(feature = "parsing")] +fn error_expected_args(attr: &Attribute) -> Error { + let style = match attr.style { + AttrStyle::Outer => "#", + AttrStyle::Inner(_) => "#!", + }; + + let mut path = String::new(); + for segment in &attr.path.segments { + if !path.is_empty() || attr.path.leading_colon.is_some() { + path += "::"; + } + path += &segment.ident.to_string(); + } + + let msg = format!("expected attribute arguments: {}[{}(...)]", style, path); + + #[cfg(feature = "printing")] + return Error::new_spanned(attr, msg); + + #[cfg(not(feature = "printing"))] + return Error::new(attr.bracket_token.span, msg); +} + +#[cfg(feature = "parsing")] +fn enter_args<'a>(attr: &Attribute, input: ParseStream<'a>) -> Result> { + if input.is_empty() { + return Err(error_expected_args(attr)); + }; + + let content; + if input.peek(token::Paren) { + parenthesized!(content in input); + } else if input.peek(token::Bracket) { + bracketed!(content in input); + } else if input.peek(token::Brace) { + braced!(content in input); + } else { + return Err(input.error("unexpected token in attribute arguments")); + } + + if input.is_empty() { + Ok(content) + } else { + Err(input.error("unexpected token in attribute arguments")) + } +} + +ast_enum! { + /// Distinguishes between attributes that decorate an item and attributes + /// that are contained within an item. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + /// + /// # Outer attributes + /// + /// - `#[repr(transparent)]` + /// - `/// # Example` + /// - `/** Please file an issue */` + /// + /// # Inner attributes + /// + /// - `#![feature(proc_macro)]` + /// - `//! # Example` + /// - `/*! Please file an issue */` + #[cfg_attr(feature = "clone-impls", derive(Copy))] + pub enum AttrStyle { + Outer, + Inner(Token![!]), + } +} + +ast_enum_of_structs! { + /// Content of a compile-time structured attribute. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + /// + /// ## Path + /// + /// A meta path is like the `test` in `#[test]`. + /// + /// ## List + /// + /// A meta list is like the `derive(Copy)` in `#[derive(Copy)]`. + /// + /// ## NameValue + /// + /// A name-value meta is like the `path = "..."` in `#[path = + /// "sys/windows.rs"]`. + /// + /// # Syntax tree enum + /// + /// This type is a [syntax tree enum]. + /// + /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums + // + // TODO: change syntax-tree-enum link to an intra rustdoc link, currently + // blocked on https://github.com/rust-lang/rust/issues/62833 + pub enum Meta { + Path(Path), + + /// A structured list within an attribute, like `derive(Copy, Clone)`. + List(MetaList), + + /// A name-value pair within an attribute, like `feature = "nightly"`. + NameValue(MetaNameValue), + } +} + +ast_struct! { + /// A structured list within an attribute, like `derive(Copy, Clone)`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct MetaList { + pub path: Path, + pub paren_token: token::Paren, + pub nested: Punctuated, + } +} + +ast_struct! { + /// A name-value pair within an attribute, like `feature = "nightly"`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct MetaNameValue { + pub path: Path, + pub eq_token: Token![=], + pub lit: Lit, + } +} + +impl Meta { + /// Returns the identifier that begins this structured meta item. + /// + /// For example this would return the `test` in `#[test]`, the `derive` in + /// `#[derive(Copy)]`, and the `path` in `#[path = "sys/windows.rs"]`. + pub fn path(&self) -> &Path { + match self { + Meta::Path(path) => path, + Meta::List(meta) => &meta.path, + Meta::NameValue(meta) => &meta.path, + } + } +} + +ast_enum_of_structs! { + /// Element of a compile-time attribute list. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + pub enum NestedMeta { + /// A structured meta item, like the `Copy` in `#[derive(Copy)]` which + /// would be a nested `Meta::Path`. + Meta(Meta), + + /// A Rust literal, like the `"new_name"` in `#[rename("new_name")]`. + Lit(Lit), + } +} + +/// Conventional argument type associated with an invocation of an attribute +/// macro. +/// +/// For example if we are developing an attribute macro that is intended to be +/// invoked on function items as follows: +/// +/// ``` +/// # const IGNORE: &str = stringify! { +/// #[my_attribute(path = "/v1/refresh")] +/// # }; +/// pub fn refresh() { +/// /* ... */ +/// } +/// ``` +/// +/// The implementation of this macro would want to parse its attribute arguments +/// as type `AttributeArgs`. +/// +/// ``` +/// extern crate proc_macro; +/// +/// use proc_macro::TokenStream; +/// use syn::{parse_macro_input, AttributeArgs, ItemFn}; +/// +/// # const IGNORE: &str = stringify! { +/// #[proc_macro_attribute] +/// # }; +/// pub fn my_attribute(args: TokenStream, input: TokenStream) -> TokenStream { +/// let args = parse_macro_input!(args as AttributeArgs); +/// let input = parse_macro_input!(input as ItemFn); +/// +/// /* ... */ +/// # "".parse().unwrap() +/// } +/// ``` +pub type AttributeArgs = Vec; + +pub trait FilterAttrs<'a> { + type Ret: Iterator; + + fn outer(self) -> Self::Ret; + fn inner(self) -> Self::Ret; +} + +impl<'a, T> FilterAttrs<'a> for T +where + T: IntoIterator, +{ + type Ret = iter::Filter bool>; + + fn outer(self) -> Self::Ret { + fn is_outer(attr: &&Attribute) -> bool { + match attr.style { + AttrStyle::Outer => true, + _ => false, + } + } + self.into_iter().filter(is_outer) + } + + fn inner(self) -> Self::Ret { + fn is_inner(attr: &&Attribute) -> bool { + match attr.style { + AttrStyle::Inner(_) => true, + _ => false, + } + } + self.into_iter().filter(is_inner) + } +} + +#[cfg(feature = "parsing")] +pub mod parsing { + use super::*; + + use crate::ext::IdentExt; + use crate::parse::{Parse, ParseStream, Result}; + #[cfg(feature = "full")] + use crate::private; + + pub fn single_parse_inner(input: ParseStream) -> Result { + let content; + Ok(Attribute { + pound_token: input.parse()?, + style: AttrStyle::Inner(input.parse()?), + bracket_token: bracketed!(content in input), + path: content.call(Path::parse_mod_style)?, + tokens: content.parse()?, + }) + } + + pub fn single_parse_outer(input: ParseStream) -> Result { + let content; + Ok(Attribute { + pound_token: input.parse()?, + style: AttrStyle::Outer, + bracket_token: bracketed!(content in input), + path: content.call(Path::parse_mod_style)?, + tokens: content.parse()?, + }) + } + + #[cfg(feature = "full")] + impl private { + pub fn attrs(outer: Vec, inner: Vec) -> Vec { + let mut attrs = outer; + attrs.extend(inner); + attrs + } + } + + // Like Path::parse_mod_style but accepts keywords in the path. + fn parse_meta_path(input: ParseStream) -> Result { + Ok(Path { + leading_colon: input.parse()?, + segments: { + let mut segments = Punctuated::new(); + while input.peek(Ident::peek_any) { + let ident = Ident::parse_any(input)?; + segments.push_value(PathSegment::from(ident)); + if !input.peek(Token![::]) { + break; + } + let punct = input.parse()?; + segments.push_punct(punct); + } + if segments.is_empty() { + return Err(input.error("expected path")); + } else if segments.trailing_punct() { + return Err(input.error("expected path segment")); + } + segments + }, + }) + } + + impl Parse for Meta { + fn parse(input: ParseStream) -> Result { + let path = input.call(parse_meta_path)?; + parse_meta_after_path(path, input) + } + } + + impl Parse for MetaList { + fn parse(input: ParseStream) -> Result { + let path = input.call(parse_meta_path)?; + parse_meta_list_after_path(path, input) + } + } + + impl Parse for MetaNameValue { + fn parse(input: ParseStream) -> Result { + let path = input.call(parse_meta_path)?; + parse_meta_name_value_after_path(path, input) + } + } + + impl Parse for NestedMeta { + fn parse(input: ParseStream) -> Result { + if input.peek(Lit) && !(input.peek(LitBool) && input.peek2(Token![=])) { + input.parse().map(NestedMeta::Lit) + } else if input.peek(Ident::peek_any) { + input.parse().map(NestedMeta::Meta) + } else { + Err(input.error("expected identifier or literal")) + } + } + } + + pub fn parse_meta_after_path(path: Path, input: ParseStream) -> Result { + if input.peek(token::Paren) { + parse_meta_list_after_path(path, input).map(Meta::List) + } else if input.peek(Token![=]) { + parse_meta_name_value_after_path(path, input).map(Meta::NameValue) + } else { + Ok(Meta::Path(path)) + } + } + + fn parse_meta_list_after_path(path: Path, input: ParseStream) -> Result { + let content; + Ok(MetaList { + path, + paren_token: parenthesized!(content in input), + nested: content.parse_terminated(NestedMeta::parse)?, + }) + } + + fn parse_meta_name_value_after_path(path: Path, input: ParseStream) -> Result { + Ok(MetaNameValue { + path, + eq_token: input.parse()?, + lit: input.parse()?, + }) + } +} + +#[cfg(feature = "printing")] +mod printing { + use super::*; + use proc_macro2::TokenStream; + use quote::ToTokens; + + impl ToTokens for Attribute { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.pound_token.to_tokens(tokens); + if let AttrStyle::Inner(b) = &self.style { + b.to_tokens(tokens); + } + self.bracket_token.surround(tokens, |tokens| { + self.path.to_tokens(tokens); + self.tokens.to_tokens(tokens); + }); + } + } + + impl ToTokens for MetaList { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.path.to_tokens(tokens); + self.paren_token.surround(tokens, |tokens| { + self.nested.to_tokens(tokens); + }) + } + } + + impl ToTokens for MetaNameValue { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.path.to_tokens(tokens); + self.eq_token.to_tokens(tokens); + self.lit.to_tokens(tokens); + } + } +} diff --git a/syn/src/await.rs b/syn/src/await.rs new file mode 100644 index 0000000..a8e24fd --- /dev/null +++ b/syn/src/await.rs @@ -0,0 +1,2 @@ +// See include!("await.rs") in token.rs. +export_token_macro![(await)]; diff --git a/syn/src/bigint.rs b/syn/src/bigint.rs new file mode 100644 index 0000000..5397d6b --- /dev/null +++ b/syn/src/bigint.rs @@ -0,0 +1,66 @@ +use std::ops::{AddAssign, MulAssign}; + +// For implementing base10_digits() accessor on LitInt. +pub struct BigInt { + digits: Vec, +} + +impl BigInt { + pub fn new() -> Self { + BigInt { digits: Vec::new() } + } + + pub fn to_string(&self) -> String { + let mut repr = String::with_capacity(self.digits.len()); + + let mut has_nonzero = false; + for digit in self.digits.iter().rev() { + has_nonzero |= *digit != 0; + if has_nonzero { + repr.push((*digit + b'0') as char); + } + } + + if repr.is_empty() { + repr.push('0'); + } + + repr + } + + fn reserve_two_digits(&mut self) { + let len = self.digits.len(); + let desired = + len + !self.digits.ends_with(&[0, 0]) as usize + !self.digits.ends_with(&[0]) as usize; + self.digits.resize(desired, 0); + } +} + +impl AddAssign for BigInt { + // Assumes increment <16. + fn add_assign(&mut self, mut increment: u8) { + self.reserve_two_digits(); + + let mut i = 0; + while increment > 0 { + let sum = self.digits[i] + increment; + self.digits[i] = sum % 10; + increment = sum / 10; + i += 1; + } + } +} + +impl MulAssign for BigInt { + // Assumes base <=16. + fn mul_assign(&mut self, base: u8) { + self.reserve_two_digits(); + + let mut carry = 0; + for digit in &mut self.digits { + let prod = *digit * base + carry; + *digit = prod % 10; + carry = prod / 10; + } + } +} diff --git a/syn/src/buffer.rs b/syn/src/buffer.rs new file mode 100644 index 0000000..5c2dd8a --- /dev/null +++ b/syn/src/buffer.rs @@ -0,0 +1,382 @@ +//! A stably addressed token buffer supporting efficient traversal based on a +//! cheaply copyable cursor. +//! +//! *This module is available if Syn is built with the `"parsing"` feature.* + +// This module is heavily commented as it contains most of the unsafe code in +// Syn, and caution should be used when editing it. The public-facing interface +// is 100% safe but the implementation is fragile internally. + +#[cfg(all( + not(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "wasi"))), + feature = "proc-macro" +))] +use crate::proc_macro as pm; +use proc_macro2::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree}; + +use std::marker::PhantomData; +use std::ptr; + +use crate::Lifetime; + +/// Internal type which is used instead of `TokenTree` to represent a token tree +/// within a `TokenBuffer`. +enum Entry { + // Mimicking types from proc-macro. + Group(Group, TokenBuffer), + Ident(Ident), + Punct(Punct), + Literal(Literal), + // End entries contain a raw pointer to the entry from the containing + // token tree, or null if this is the outermost level. + End(*const Entry), +} + +/// A buffer that can be efficiently traversed multiple times, unlike +/// `TokenStream` which requires a deep copy in order to traverse more than +/// once. +/// +/// *This type is available if Syn is built with the `"parsing"` feature.* +pub struct TokenBuffer { + // NOTE: Do not derive clone on this - there are raw pointers inside which + // will be messed up. Moving the `TokenBuffer` itself is safe as the actual + // backing slices won't be moved. + data: Box<[Entry]>, +} + +impl TokenBuffer { + // NOTE: DO NOT MUTATE THE `Vec` RETURNED FROM THIS FUNCTION ONCE IT + // RETURNS, THE ADDRESS OF ITS BACKING MEMORY MUST REMAIN STABLE. + fn inner_new(stream: TokenStream, up: *const Entry) -> TokenBuffer { + // Build up the entries list, recording the locations of any Groups + // in the list to be processed later. + let mut entries = Vec::new(); + let mut seqs = Vec::new(); + for tt in stream { + match tt { + TokenTree::Ident(sym) => { + entries.push(Entry::Ident(sym)); + } + TokenTree::Punct(op) => { + entries.push(Entry::Punct(op)); + } + TokenTree::Literal(l) => { + entries.push(Entry::Literal(l)); + } + TokenTree::Group(g) => { + // Record the index of the interesting entry, and store an + // `End(null)` there temporarially. + seqs.push((entries.len(), g)); + entries.push(Entry::End(ptr::null())); + } + } + } + // Add an `End` entry to the end with a reference to the enclosing token + // stream which was passed in. + entries.push(Entry::End(up)); + + // NOTE: This is done to ensure that we don't accidentally modify the + // length of the backing buffer. The backing buffer must remain at a + // constant address after this point, as we are going to store a raw + // pointer into it. + let mut entries = entries.into_boxed_slice(); + for (idx, group) in seqs { + // We know that this index refers to one of the temporary + // `End(null)` entries, and we know that the last entry is + // `End(up)`, so the next index is also valid. + let seq_up = &entries[idx + 1] as *const Entry; + + // The end entry stored at the end of this Entry::Group should + // point to the Entry which follows the Group in the list. + let inner = Self::inner_new(group.stream(), seq_up); + entries[idx] = Entry::Group(group, inner); + } + + TokenBuffer { data: entries } + } + + /// Creates a `TokenBuffer` containing all the tokens from the input + /// `TokenStream`. + /// + /// *This method is available if Syn is built with both the `"parsing"` and + /// `"proc-macro"` features.* + #[cfg(all( + not(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "wasi"))), + feature = "proc-macro" + ))] + pub fn new(stream: pm::TokenStream) -> TokenBuffer { + Self::new2(stream.into()) + } + + /// Creates a `TokenBuffer` containing all the tokens from the input + /// `TokenStream`. + pub fn new2(stream: TokenStream) -> TokenBuffer { + Self::inner_new(stream, ptr::null()) + } + + /// Creates a cursor referencing the first token in the buffer and able to + /// traverse until the end of the buffer. + pub fn begin(&self) -> Cursor { + unsafe { Cursor::create(&self.data[0], &self.data[self.data.len() - 1]) } + } +} + +/// A cheaply copyable cursor into a `TokenBuffer`. +/// +/// This cursor holds a shared reference into the immutable data which is used +/// internally to represent a `TokenStream`, and can be efficiently manipulated +/// and copied around. +/// +/// An empty `Cursor` can be created directly, or one may create a `TokenBuffer` +/// object and get a cursor to its first token with `begin()`. +/// +/// Two cursors are equal if they have the same location in the same input +/// stream, and have the same scope. +/// +/// *This type is available if Syn is built with the `"parsing"` feature.* +#[derive(Copy, Clone, Eq, PartialEq)] +pub struct Cursor<'a> { + // The current entry which the `Cursor` is pointing at. + ptr: *const Entry, + // This is the only `Entry::End(..)` object which this cursor is allowed to + // point at. All other `End` objects are skipped over in `Cursor::create`. + scope: *const Entry, + // Cursor is covariant in 'a. This field ensures that our pointers are still + // valid. + marker: PhantomData<&'a Entry>, +} + +impl<'a> Cursor<'a> { + /// Creates a cursor referencing a static empty TokenStream. + pub fn empty() -> Self { + // It's safe in this situation for us to put an `Entry` object in global + // storage, despite it not actually being safe to send across threads + // (`Ident` is a reference into a thread-local table). This is because + // this entry never includes a `Ident` object. + // + // This wrapper struct allows us to break the rules and put a `Sync` + // object in global storage. + struct UnsafeSyncEntry(Entry); + unsafe impl Sync for UnsafeSyncEntry {} + static EMPTY_ENTRY: UnsafeSyncEntry = UnsafeSyncEntry(Entry::End(0 as *const Entry)); + + Cursor { + ptr: &EMPTY_ENTRY.0, + scope: &EMPTY_ENTRY.0, + marker: PhantomData, + } + } + + /// This create method intelligently exits non-explicitly-entered + /// `None`-delimited scopes when the cursor reaches the end of them, + /// allowing for them to be treated transparently. + unsafe fn create(mut ptr: *const Entry, scope: *const Entry) -> Self { + // NOTE: If we're looking at a `End(..)`, we want to advance the cursor + // past it, unless `ptr == scope`, which means that we're at the edge of + // our cursor's scope. We should only have `ptr != scope` at the exit + // from None-delimited groups entered with `ignore_none`. + while let Entry::End(exit) = *ptr { + if ptr == scope { + break; + } + ptr = exit; + } + + Cursor { + ptr, + scope, + marker: PhantomData, + } + } + + /// Get the current entry. + fn entry(self) -> &'a Entry { + unsafe { &*self.ptr } + } + + /// Bump the cursor to point at the next token after the current one. This + /// is undefined behavior if the cursor is currently looking at an + /// `Entry::End`. + unsafe fn bump(self) -> Cursor<'a> { + Cursor::create(self.ptr.offset(1), self.scope) + } + + /// If the cursor is looking at a `None`-delimited group, move it to look at + /// the first token inside instead. If the group is empty, this will move + /// the cursor past the `None`-delimited group. + /// + /// WARNING: This mutates its argument. + fn ignore_none(&mut self) { + if let Entry::Group(group, buf) = self.entry() { + if group.delimiter() == Delimiter::None { + // NOTE: We call `Cursor::create` here to make sure that + // situations where we should immediately exit the span after + // entering it are handled correctly. + unsafe { + *self = Cursor::create(&buf.data[0], self.scope); + } + } + } + } + + /// Checks whether the cursor is currently pointing at the end of its valid + /// scope. + pub fn eof(self) -> bool { + // We're at eof if we're at the end of our scope. + self.ptr == self.scope + } + + /// If the cursor is pointing at a `Group` with the given delimiter, returns + /// a cursor into that group and one pointing to the next `TokenTree`. + pub fn group(mut self, delim: Delimiter) -> Option<(Cursor<'a>, Span, Cursor<'a>)> { + // If we're not trying to enter a none-delimited group, we want to + // ignore them. We have to make sure to _not_ ignore them when we want + // to enter them, of course. For obvious reasons. + if delim != Delimiter::None { + self.ignore_none(); + } + + if let Entry::Group(group, buf) = self.entry() { + if group.delimiter() == delim { + return Some((buf.begin(), group.span(), unsafe { self.bump() })); + } + } + + None + } + + /// If the cursor is pointing at a `Ident`, returns it along with a cursor + /// pointing at the next `TokenTree`. + pub fn ident(mut self) -> Option<(Ident, Cursor<'a>)> { + self.ignore_none(); + match self.entry() { + Entry::Ident(ident) => Some((ident.clone(), unsafe { self.bump() })), + _ => None, + } + } + + /// If the cursor is pointing at an `Punct`, returns it along with a cursor + /// pointing at the next `TokenTree`. + pub fn punct(mut self) -> Option<(Punct, Cursor<'a>)> { + self.ignore_none(); + match self.entry() { + Entry::Punct(op) if op.as_char() != '\'' => Some((op.clone(), unsafe { self.bump() })), + _ => None, + } + } + + /// If the cursor is pointing at a `Literal`, return it along with a cursor + /// pointing at the next `TokenTree`. + pub fn literal(mut self) -> Option<(Literal, Cursor<'a>)> { + self.ignore_none(); + match self.entry() { + Entry::Literal(lit) => Some((lit.clone(), unsafe { self.bump() })), + _ => None, + } + } + + /// If the cursor is pointing at a `Lifetime`, returns it along with a + /// cursor pointing at the next `TokenTree`. + pub fn lifetime(mut self) -> Option<(Lifetime, Cursor<'a>)> { + self.ignore_none(); + match self.entry() { + Entry::Punct(op) if op.as_char() == '\'' && op.spacing() == Spacing::Joint => { + let next = unsafe { self.bump() }; + match next.ident() { + Some((ident, rest)) => { + let lifetime = Lifetime { + apostrophe: op.span(), + ident, + }; + Some((lifetime, rest)) + } + None => None, + } + } + _ => None, + } + } + + /// Copies all remaining tokens visible from this cursor into a + /// `TokenStream`. + pub fn token_stream(self) -> TokenStream { + let mut tts = Vec::new(); + let mut cursor = self; + while let Some((tt, rest)) = cursor.token_tree() { + tts.push(tt); + cursor = rest; + } + tts.into_iter().collect() + } + + /// If the cursor is pointing at a `TokenTree`, returns it along with a + /// cursor pointing at the next `TokenTree`. + /// + /// Returns `None` if the cursor has reached the end of its stream. + /// + /// This method does not treat `None`-delimited groups as transparent, and + /// will return a `Group(None, ..)` if the cursor is looking at one. + pub fn token_tree(self) -> Option<(TokenTree, Cursor<'a>)> { + let tree = match self.entry() { + Entry::Group(group, _) => group.clone().into(), + Entry::Literal(lit) => lit.clone().into(), + Entry::Ident(ident) => ident.clone().into(), + Entry::Punct(op) => op.clone().into(), + Entry::End(..) => { + return None; + } + }; + + Some((tree, unsafe { self.bump() })) + } + + /// Returns the `Span` of the current token, or `Span::call_site()` if this + /// cursor points to eof. + pub fn span(self) -> Span { + match self.entry() { + Entry::Group(group, _) => group.span(), + Entry::Literal(l) => l.span(), + Entry::Ident(t) => t.span(), + Entry::Punct(o) => o.span(), + Entry::End(..) => Span::call_site(), + } + } + + /// Skip over the next token without cloning it. Returns `None` if this + /// cursor points to eof. + /// + /// This method treats `'lifetimes` as a single token. + pub(crate) fn skip(self) -> Option> { + match self.entry() { + Entry::End(..) => None, + + // Treat lifetimes as a single tt for the purposes of 'skip'. + Entry::Punct(op) if op.as_char() == '\'' && op.spacing() == Spacing::Joint => { + let next = unsafe { self.bump() }; + match next.entry() { + Entry::Ident(_) => Some(unsafe { next.bump() }), + _ => Some(next), + } + } + _ => Some(unsafe { self.bump() }), + } + } +} + +pub(crate) fn same_scope(a: Cursor, b: Cursor) -> bool { + a.scope == b.scope +} + +pub(crate) fn open_span_of_group(cursor: Cursor) -> Span { + match cursor.entry() { + Entry::Group(group, _) => group.span_open(), + _ => cursor.span(), + } +} + +pub(crate) fn close_span_of_group(cursor: Cursor) -> Span { + match cursor.entry() { + Entry::Group(group, _) => group.span_close(), + _ => cursor.span(), + } +} diff --git a/syn/src/custom_keyword.rs b/syn/src/custom_keyword.rs new file mode 100644 index 0000000..200e847 --- /dev/null +++ b/syn/src/custom_keyword.rs @@ -0,0 +1,252 @@ +/// Define a type that supports parsing and printing a given identifier as if it +/// were a keyword. +/// +/// # Usage +/// +/// As a convention, it is recommended that this macro be invoked within a +/// module called `kw` or `keyword` and that the resulting parser be invoked +/// with a `kw::` or `keyword::` prefix. +/// +/// ``` +/// mod kw { +/// syn::custom_keyword!(whatever); +/// } +/// ``` +/// +/// The generated syntax tree node supports the following operations just like +/// any built-in keyword token. +/// +/// - [Peeking] — `input.peek(kw::whatever)` +/// +/// - [Parsing] — `input.parse::()?` +/// +/// - [Printing] — `quote!( ... #whatever_token ... )` +/// +/// - Construction from a [`Span`] — `let whatever_token = kw::whatever(sp)` +/// +/// - Field access to its span — `let sp = whatever_token.span` +/// +/// [Peeking]: parse::ParseBuffer::peek +/// [Parsing]: parse::ParseBuffer::parse +/// [Printing]: quote::ToTokens +/// [`Span`]: proc_macro2::Span +/// +/// # Example +/// +/// This example parses input that looks like `bool = true` or `str = "value"`. +/// The key must be either the identifier `bool` or the identifier `str`. If +/// `bool`, the value may be either `true` or `false`. If `str`, the value may +/// be any string literal. +/// +/// The symbols `bool` and `str` are not reserved keywords in Rust so these are +/// not considered keywords in the `syn::token` module. Like any other +/// identifier that is not a keyword, these can be declared as custom keywords +/// by crates that need to use them as such. +/// +/// ``` +/// use syn::{LitBool, LitStr, Result, Token}; +/// use syn::parse::{Parse, ParseStream}; +/// +/// mod kw { +/// syn::custom_keyword!(bool); +/// syn::custom_keyword!(str); +/// } +/// +/// enum Argument { +/// Bool { +/// bool_token: kw::bool, +/// eq_token: Token![=], +/// value: LitBool, +/// }, +/// Str { +/// str_token: kw::str, +/// eq_token: Token![=], +/// value: LitStr, +/// }, +/// } +/// +/// impl Parse for Argument { +/// fn parse(input: ParseStream) -> Result { +/// let lookahead = input.lookahead1(); +/// if lookahead.peek(kw::bool) { +/// Ok(Argument::Bool { +/// bool_token: input.parse::()?, +/// eq_token: input.parse()?, +/// value: input.parse()?, +/// }) +/// } else if lookahead.peek(kw::str) { +/// Ok(Argument::Str { +/// str_token: input.parse::()?, +/// eq_token: input.parse()?, +/// value: input.parse()?, +/// }) +/// } else { +/// Err(lookahead.error()) +/// } +/// } +/// } +/// ``` +#[macro_export(local_inner_macros)] +macro_rules! custom_keyword { + ($ident:ident) => { + #[allow(non_camel_case_types)] + pub struct $ident { + pub span: $crate::export::Span, + } + + #[doc(hidden)] + #[allow(non_snake_case)] + pub fn $ident<__S: $crate::export::IntoSpans<[$crate::export::Span; 1]>>( + span: __S, + ) -> $ident { + $ident { + span: $crate::export::IntoSpans::into_spans(span)[0], + } + } + + impl $crate::export::Default for $ident { + fn default() -> Self { + $ident { + span: $crate::export::Span::call_site(), + } + } + } + + impl_parse_for_custom_keyword!($ident); + impl_to_tokens_for_custom_keyword!($ident); + impl_clone_for_custom_keyword!($ident); + impl_extra_traits_for_custom_keyword!($ident); + }; +} + +// Not public API. +#[cfg(feature = "parsing")] +#[doc(hidden)] +#[macro_export] +macro_rules! impl_parse_for_custom_keyword { + ($ident:ident) => { + // For peek. + impl $crate::token::CustomToken for $ident { + fn peek(cursor: $crate::buffer::Cursor) -> $crate::export::bool { + if let Some((ident, _rest)) = cursor.ident() { + ident == stringify!($ident) + } else { + false + } + } + + fn display() -> &'static $crate::export::str { + concat!("`", stringify!($ident), "`") + } + } + + impl $crate::parse::Parse for $ident { + fn parse(input: $crate::parse::ParseStream) -> $crate::parse::Result<$ident> { + input.step(|cursor| { + if let $crate::export::Some((ident, rest)) = cursor.ident() { + if ident == stringify!($ident) { + return $crate::export::Ok(($ident { span: ident.span() }, rest)); + } + } + $crate::export::Err(cursor.error(concat!( + "expected `", + stringify!($ident), + "`" + ))) + }) + } + } + }; +} + +// Not public API. +#[cfg(not(feature = "parsing"))] +#[doc(hidden)] +#[macro_export] +macro_rules! impl_parse_for_custom_keyword { + ($ident:ident) => {}; +} + +// Not public API. +#[cfg(feature = "printing")] +#[doc(hidden)] +#[macro_export] +macro_rules! impl_to_tokens_for_custom_keyword { + ($ident:ident) => { + impl $crate::export::ToTokens for $ident { + fn to_tokens(&self, tokens: &mut $crate::export::TokenStream2) { + let ident = $crate::Ident::new(stringify!($ident), self.span); + $crate::export::TokenStreamExt::append(tokens, ident); + } + } + }; +} + +// Not public API. +#[cfg(not(feature = "printing"))] +#[doc(hidden)] +#[macro_export] +macro_rules! impl_to_tokens_for_custom_keyword { + ($ident:ident) => {}; +} + +// Not public API. +#[cfg(feature = "clone-impls")] +#[doc(hidden)] +#[macro_export] +macro_rules! impl_clone_for_custom_keyword { + ($ident:ident) => { + impl $crate::export::Copy for $ident {} + + impl $crate::export::Clone for $ident { + fn clone(&self) -> Self { + *self + } + } + }; +} + +// Not public API. +#[cfg(not(feature = "clone-impls"))] +#[doc(hidden)] +#[macro_export] +macro_rules! impl_clone_for_custom_keyword { + ($ident:ident) => {}; +} + +// Not public API. +#[cfg(feature = "extra-traits")] +#[doc(hidden)] +#[macro_export] +macro_rules! impl_extra_traits_for_custom_keyword { + ($ident:ident) => { + impl $crate::export::Debug for $ident { + fn fmt(&self, f: &mut $crate::export::Formatter) -> $crate::export::fmt::Result { + $crate::export::Formatter::write_str( + f, + concat!("Keyword [", stringify!($ident), "]"), + ) + } + } + + impl $crate::export::Eq for $ident {} + + impl $crate::export::PartialEq for $ident { + fn eq(&self, _other: &Self) -> $crate::export::bool { + true + } + } + + impl $crate::export::Hash for $ident { + fn hash<__H: $crate::export::Hasher>(&self, _state: &mut __H) {} + } + }; +} + +// Not public API. +#[cfg(not(feature = "extra-traits"))] +#[doc(hidden)] +#[macro_export] +macro_rules! impl_extra_traits_for_custom_keyword { + ($ident:ident) => {}; +} diff --git a/syn/src/custom_punctuation.rs b/syn/src/custom_punctuation.rs new file mode 100644 index 0000000..29fa448 --- /dev/null +++ b/syn/src/custom_punctuation.rs @@ -0,0 +1,309 @@ +/// Define a type that supports parsing and printing a multi-character symbol +/// as if it were a punctuation token. +/// +/// # Usage +/// +/// ``` +/// syn::custom_punctuation!(LeftRightArrow, <=>); +/// ``` +/// +/// The generated syntax tree node supports the following operations just like +/// any built-in punctuation token. +/// +/// - [Peeking] — `input.peek(LeftRightArrow)` +/// +/// - [Parsing] — `input.parse::()?` +/// +/// - [Printing] — `quote!( ... #lrarrow ... )` +/// +/// - Construction from a [`Span`] — `let lrarrow = LeftRightArrow(sp)` +/// +/// - Construction from multiple [`Span`] — `let lrarrow = LeftRightArrow([sp, sp, sp])` +/// +/// - Field access to its spans — `let spans = lrarrow.spans` +/// +/// [Peeking]: parse::ParseBuffer::peek +/// [Parsing]: parse::ParseBuffer::parse +/// [Printing]: quote::ToTokens +/// [`Span`]: proc_macro2::Span +/// +/// # Example +/// +/// ``` +/// use proc_macro2::{TokenStream, TokenTree}; +/// use syn::parse::{Parse, ParseStream, Peek, Result}; +/// use syn::punctuated::Punctuated; +/// use syn::Expr; +/// +/// syn::custom_punctuation!(PathSeparator, ); +/// +/// // expr expr expr ... +/// struct PathSegments { +/// segments: Punctuated, +/// } +/// +/// impl Parse for PathSegments { +/// fn parse(input: ParseStream) -> Result { +/// let mut segments = Punctuated::new(); +/// +/// let first = parse_until(input, PathSeparator)?; +/// segments.push_value(syn::parse2(first)?); +/// +/// while input.peek(PathSeparator) { +/// segments.push_punct(input.parse()?); +/// +/// let next = parse_until(input, PathSeparator)?; +/// segments.push_value(syn::parse2(next)?); +/// } +/// +/// Ok(PathSegments { segments }) +/// } +/// } +/// +/// fn parse_until(input: ParseStream, end: E) -> Result { +/// let mut tokens = TokenStream::new(); +/// while !input.is_empty() && !input.peek(end) { +/// let next: TokenTree = input.parse()?; +/// tokens.extend(Some(next)); +/// } +/// Ok(tokens) +/// } +/// +/// fn main() { +/// let input = r#" a::b c::d::e "#; +/// let _: PathSegments = syn::parse_str(input).unwrap(); +/// } +/// ``` +#[macro_export(local_inner_macros)] +macro_rules! custom_punctuation { + ($ident:ident, $($tt:tt)+) => { + pub struct $ident { + pub spans: custom_punctuation_repr!($($tt)+), + } + + #[doc(hidden)] + #[allow(non_snake_case)] + pub fn $ident<__S: $crate::export::IntoSpans>( + spans: __S, + ) -> $ident { + let _validate_len = 0 $(+ custom_punctuation_len!(strict, $tt))*; + $ident { + spans: $crate::export::IntoSpans::into_spans(spans) + } + } + + impl $crate::export::Default for $ident { + fn default() -> Self { + $ident($crate::export::Span::call_site()) + } + } + + impl_parse_for_custom_punctuation!($ident, $($tt)+); + impl_to_tokens_for_custom_punctuation!($ident, $($tt)+); + impl_clone_for_custom_punctuation!($ident, $($tt)+); + impl_extra_traits_for_custom_punctuation!($ident, $($tt)+); + }; +} + +// Not public API. +#[cfg(feature = "parsing")] +#[doc(hidden)] +#[macro_export(local_inner_macros)] +macro_rules! impl_parse_for_custom_punctuation { + ($ident:ident, $($tt:tt)+) => { + impl $crate::token::CustomToken for $ident { + fn peek(cursor: $crate::buffer::Cursor) -> bool { + $crate::token::parsing::peek_punct(cursor, stringify_punct!($($tt)+)) + } + + fn display() -> &'static $crate::export::str { + custom_punctuation_concat!("`", stringify_punct!($($tt)+), "`") + } + } + + impl $crate::parse::Parse for $ident { + fn parse(input: $crate::parse::ParseStream) -> $crate::parse::Result<$ident> { + let spans: custom_punctuation_repr!($($tt)+) = + $crate::token::parsing::punct(input, stringify_punct!($($tt)+))?; + Ok($ident(spans)) + } + } + }; +} + +// Not public API. +#[cfg(not(feature = "parsing"))] +#[doc(hidden)] +#[macro_export] +macro_rules! impl_parse_for_custom_punctuation { + ($ident:ident, $($tt:tt)+) => {}; +} + +// Not public API. +#[cfg(feature = "printing")] +#[doc(hidden)] +#[macro_export(local_inner_macros)] +macro_rules! impl_to_tokens_for_custom_punctuation { + ($ident:ident, $($tt:tt)+) => { + impl $crate::export::ToTokens for $ident { + fn to_tokens(&self, tokens: &mut $crate::export::TokenStream2) { + $crate::token::printing::punct(stringify_punct!($($tt)+), &self.spans, tokens) + } + } + }; +} + +// Not public API. +#[cfg(not(feature = "printing"))] +#[doc(hidden)] +#[macro_export] +macro_rules! impl_to_tokens_for_custom_punctuation { + ($ident:ident, $($tt:tt)+) => {}; +} + +// Not public API. +#[cfg(feature = "clone-impls")] +#[doc(hidden)] +#[macro_export] +macro_rules! impl_clone_for_custom_punctuation { + ($ident:ident, $($tt:tt)+) => { + impl $crate::export::Copy for $ident {} + + impl $crate::export::Clone for $ident { + fn clone(&self) -> Self { + *self + } + } + }; +} + +// Not public API. +#[cfg(not(feature = "clone-impls"))] +#[doc(hidden)] +#[macro_export] +macro_rules! impl_clone_for_custom_punctuation { + ($ident:ident, $($tt:tt)+) => {}; +} + +// Not public API. +#[cfg(feature = "extra-traits")] +#[doc(hidden)] +#[macro_export] +macro_rules! impl_extra_traits_for_custom_punctuation { + ($ident:ident, $($tt:tt)+) => { + impl $crate::export::Debug for $ident { + fn fmt(&self, f: &mut $crate::export::Formatter) -> $crate::export::fmt::Result { + $crate::export::Formatter::write_str(f, stringify!($ident)) + } + } + + impl $crate::export::Eq for $ident {} + + impl $crate::export::PartialEq for $ident { + fn eq(&self, _other: &Self) -> $crate::export::bool { + true + } + } + + impl $crate::export::Hash for $ident { + fn hash<__H: $crate::export::Hasher>(&self, _state: &mut __H) {} + } + }; +} + +// Not public API. +#[cfg(not(feature = "extra-traits"))] +#[doc(hidden)] +#[macro_export] +macro_rules! impl_extra_traits_for_custom_punctuation { + ($ident:ident, $($tt:tt)+) => {}; +} + +// Not public API. +#[doc(hidden)] +#[macro_export(local_inner_macros)] +macro_rules! custom_punctuation_repr { + ($($tt:tt)+) => { + [$crate::export::Span; 0 $(+ custom_punctuation_len!(lenient, $tt))+] + }; +} + +// Not public API. +#[doc(hidden)] +#[macro_export(local_inner_macros)] +#[rustfmt::skip] +macro_rules! custom_punctuation_len { + ($mode:ident, +) => { 1 }; + ($mode:ident, +=) => { 2 }; + ($mode:ident, &) => { 1 }; + ($mode:ident, &&) => { 2 }; + ($mode:ident, &=) => { 2 }; + ($mode:ident, @) => { 1 }; + ($mode:ident, !) => { 1 }; + ($mode:ident, ^) => { 1 }; + ($mode:ident, ^=) => { 2 }; + ($mode:ident, :) => { 1 }; + ($mode:ident, ::) => { 2 }; + ($mode:ident, ,) => { 1 }; + ($mode:ident, /) => { 1 }; + ($mode:ident, /=) => { 2 }; + ($mode:ident, .) => { 1 }; + ($mode:ident, ..) => { 2 }; + ($mode:ident, ...) => { 3 }; + ($mode:ident, ..=) => { 3 }; + ($mode:ident, =) => { 1 }; + ($mode:ident, ==) => { 2 }; + ($mode:ident, >=) => { 2 }; + ($mode:ident, >) => { 1 }; + ($mode:ident, <=) => { 2 }; + ($mode:ident, <) => { 1 }; + ($mode:ident, *=) => { 2 }; + ($mode:ident, !=) => { 2 }; + ($mode:ident, |) => { 1 }; + ($mode:ident, |=) => { 2 }; + ($mode:ident, ||) => { 2 }; + ($mode:ident, #) => { 1 }; + ($mode:ident, ?) => { 1 }; + ($mode:ident, ->) => { 2 }; + ($mode:ident, <-) => { 2 }; + ($mode:ident, %) => { 1 }; + ($mode:ident, %=) => { 2 }; + ($mode:ident, =>) => { 2 }; + ($mode:ident, ;) => { 1 }; + ($mode:ident, <<) => { 2 }; + ($mode:ident, <<=) => { 3 }; + ($mode:ident, >>) => { 2 }; + ($mode:ident, >>=) => { 3 }; + ($mode:ident, *) => { 1 }; + ($mode:ident, -) => { 1 }; + ($mode:ident, -=) => { 2 }; + ($mode:ident, ~) => { 1 }; + (lenient, $tt:tt) => { 0 }; + (strict, $tt:tt) => {{ custom_punctuation_unexpected!($tt); 0 }}; +} + +// Not public API. +#[doc(hidden)] +#[macro_export] +macro_rules! custom_punctuation_unexpected { + () => {}; +} + +// Not public API. +#[doc(hidden)] +#[macro_export] +macro_rules! stringify_punct { + ($($tt:tt)+) => { + concat!($(stringify!($tt)),+) + }; +} + +// Not public API. +// Without this, local_inner_macros breaks when looking for concat! +#[doc(hidden)] +#[macro_export] +macro_rules! custom_punctuation_concat { + ($($tt:tt)*) => { + concat!($($tt)*) + }; +} diff --git a/syn/src/data.rs b/syn/src/data.rs new file mode 100644 index 0000000..184a79e --- /dev/null +++ b/syn/src/data.rs @@ -0,0 +1,456 @@ +use super::*; +use crate::punctuated::Punctuated; + +ast_struct! { + /// An enum variant. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + pub struct Variant { + /// Attributes tagged on the variant. + pub attrs: Vec, + + /// Name of the variant. + pub ident: Ident, + + /// Content stored in the variant. + pub fields: Fields, + + /// Explicit discriminant: `Variant = 1` + pub discriminant: Option<(Token![=], Expr)>, + } +} + +ast_enum_of_structs! { + /// Data stored within an enum variant or struct. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + /// + /// # Syntax tree enum + /// + /// This type is a [syntax tree enum]. + /// + /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums + // + // TODO: change syntax-tree-enum link to an intra rustdoc link, currently + // blocked on https://github.com/rust-lang/rust/issues/62833 + pub enum Fields { + /// Named fields of a struct or struct variant such as `Point { x: f64, + /// y: f64 }`. + Named(FieldsNamed), + + /// Unnamed fields of a tuple struct or tuple variant such as `Some(T)`. + Unnamed(FieldsUnnamed), + + /// Unit struct or unit variant such as `None`. + Unit, + } +} + +ast_struct! { + /// Named fields of a struct or struct variant such as `Point { x: f64, + /// y: f64 }`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct FieldsNamed { + pub brace_token: token::Brace, + pub named: Punctuated, + } +} + +ast_struct! { + /// Unnamed fields of a tuple struct or tuple variant such as `Some(T)`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct FieldsUnnamed { + pub paren_token: token::Paren, + pub unnamed: Punctuated, + } +} + +impl Fields { + /// Get an iterator over the borrowed [`Field`] items in this object. This + /// iterator can be used to iterate over a named or unnamed struct or + /// variant's fields uniformly. + pub fn iter(&self) -> punctuated::Iter { + match self { + Fields::Unit => crate::punctuated::empty_punctuated_iter(), + Fields::Named(f) => f.named.iter(), + Fields::Unnamed(f) => f.unnamed.iter(), + } + } + + /// Get an iterator over the mutably borrowed [`Field`] items in this + /// object. This iterator can be used to iterate over a named or unnamed + /// struct or variant's fields uniformly. + pub fn iter_mut(&mut self) -> punctuated::IterMut { + match self { + Fields::Unit => crate::punctuated::empty_punctuated_iter_mut(), + Fields::Named(f) => f.named.iter_mut(), + Fields::Unnamed(f) => f.unnamed.iter_mut(), + } + } + + /// Returns the number of fields. + pub fn len(&self) -> usize { + match self { + Fields::Unit => 0, + Fields::Named(f) => f.named.len(), + Fields::Unnamed(f) => f.unnamed.len(), + } + } + + /// Returns `true` if there are zero fields. + pub fn is_empty(&self) -> bool { + match self { + Fields::Unit => true, + Fields::Named(f) => f.named.is_empty(), + Fields::Unnamed(f) => f.unnamed.is_empty(), + } + } +} + +impl IntoIterator for Fields { + type Item = Field; + type IntoIter = punctuated::IntoIter; + + fn into_iter(self) -> Self::IntoIter { + match self { + Fields::Unit => Punctuated::::new().into_iter(), + Fields::Named(f) => f.named.into_iter(), + Fields::Unnamed(f) => f.unnamed.into_iter(), + } + } +} + +impl<'a> IntoIterator for &'a Fields { + type Item = &'a Field; + type IntoIter = punctuated::Iter<'a, Field>; + + fn into_iter(self) -> Self::IntoIter { + self.iter() + } +} + +impl<'a> IntoIterator for &'a mut Fields { + type Item = &'a mut Field; + type IntoIter = punctuated::IterMut<'a, Field>; + + fn into_iter(self) -> Self::IntoIter { + self.iter_mut() + } +} + +ast_struct! { + /// A field of a struct or enum variant. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + pub struct Field { + /// Attributes tagged on the field. + pub attrs: Vec, + + /// Visibility of the field. + pub vis: Visibility, + + /// Name of the field, if any. + /// + /// Fields of tuple structs have no names. + pub ident: Option, + + pub colon_token: Option, + + /// Type of the field. + pub ty: Type, + } +} + +ast_enum_of_structs! { + /// The visibility level of an item: inherited or `pub` or + /// `pub(restricted)`. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + /// + /// # Syntax tree enum + /// + /// This type is a [syntax tree enum]. + /// + /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums + // + // TODO: change syntax-tree-enum link to an intra rustdoc link, currently + // blocked on https://github.com/rust-lang/rust/issues/62833 + pub enum Visibility { + /// A public visibility level: `pub`. + Public(VisPublic), + + /// A crate-level visibility: `crate`. + Crate(VisCrate), + + /// A visibility level restricted to some path: `pub(self)` or + /// `pub(super)` or `pub(crate)` or `pub(in some::module)`. + Restricted(VisRestricted), + + /// An inherited visibility, which usually means private. + Inherited, + } +} + +ast_struct! { + /// A public visibility level: `pub`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct VisPublic { + pub pub_token: Token![pub], + } +} + +ast_struct! { + /// A crate-level visibility: `crate`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct VisCrate { + pub crate_token: Token![crate], + } +} + +ast_struct! { + /// A visibility level restricted to some path: `pub(self)` or + /// `pub(super)` or `pub(crate)` or `pub(in some::module)`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct VisRestricted { + pub pub_token: Token![pub], + pub paren_token: token::Paren, + pub in_token: Option, + pub path: Box, + } +} + +#[cfg(feature = "parsing")] +pub mod parsing { + use super::*; + + use crate::ext::IdentExt; + use crate::parse::discouraged::Speculative; + use crate::parse::{Parse, ParseStream, Result}; + + impl Parse for Variant { + fn parse(input: ParseStream) -> Result { + Ok(Variant { + attrs: input.call(Attribute::parse_outer)?, + ident: input.parse()?, + fields: { + if input.peek(token::Brace) { + Fields::Named(input.parse()?) + } else if input.peek(token::Paren) { + Fields::Unnamed(input.parse()?) + } else { + Fields::Unit + } + }, + discriminant: { + if input.peek(Token![=]) { + let eq_token: Token![=] = input.parse()?; + let discriminant: Expr = input.parse()?; + Some((eq_token, discriminant)) + } else { + None + } + }, + }) + } + } + + impl Parse for FieldsNamed { + fn parse(input: ParseStream) -> Result { + let content; + Ok(FieldsNamed { + brace_token: braced!(content in input), + named: content.parse_terminated(Field::parse_named)?, + }) + } + } + + impl Parse for FieldsUnnamed { + fn parse(input: ParseStream) -> Result { + let content; + Ok(FieldsUnnamed { + paren_token: parenthesized!(content in input), + unnamed: content.parse_terminated(Field::parse_unnamed)?, + }) + } + } + + impl Field { + /// Parses a named (braced struct) field. + pub fn parse_named(input: ParseStream) -> Result { + Ok(Field { + attrs: input.call(Attribute::parse_outer)?, + vis: input.parse()?, + ident: Some(input.parse()?), + colon_token: Some(input.parse()?), + ty: input.parse()?, + }) + } + + /// Parses an unnamed (tuple struct) field. + pub fn parse_unnamed(input: ParseStream) -> Result { + Ok(Field { + attrs: input.call(Attribute::parse_outer)?, + vis: input.parse()?, + ident: None, + colon_token: None, + ty: input.parse()?, + }) + } + } + + impl Parse for Visibility { + fn parse(input: ParseStream) -> Result { + if input.peek(Token![pub]) { + Self::parse_pub(input) + } else if input.peek(Token![crate]) { + Self::parse_crate(input) + } else { + Ok(Visibility::Inherited) + } + } + } + + impl Visibility { + fn parse_pub(input: ParseStream) -> Result { + let pub_token = input.parse::()?; + + if input.peek(token::Paren) { + let ahead = input.fork(); + + let content; + let paren_token = parenthesized!(content in ahead); + if content.peek(Token![crate]) + || content.peek(Token![self]) + || content.peek(Token![super]) + { + let path = content.call(Ident::parse_any)?; + + // Ensure there are no additional tokens within `content`. + // Without explicitly checking, we may misinterpret a tuple + // field as a restricted visibility, causing a parse error. + // e.g. `pub (crate::A, crate::B)` (Issue #720). + if content.is_empty() { + input.advance_to(&ahead); + return Ok(Visibility::Restricted(VisRestricted { + pub_token, + paren_token, + in_token: None, + path: Box::new(Path::from(path)), + })); + } + } else if content.peek(Token![in]) { + let in_token: Token![in] = content.parse()?; + let path = content.call(Path::parse_mod_style)?; + + input.advance_to(&ahead); + return Ok(Visibility::Restricted(VisRestricted { + pub_token, + paren_token, + in_token: Some(in_token), + path: Box::new(path), + })); + } + } + + Ok(Visibility::Public(VisPublic { pub_token })) + } + + fn parse_crate(input: ParseStream) -> Result { + if input.peek2(Token![::]) { + Ok(Visibility::Inherited) + } else { + Ok(Visibility::Crate(VisCrate { + crate_token: input.parse()?, + })) + } + } + } +} + +#[cfg(feature = "printing")] +mod printing { + use super::*; + + use proc_macro2::TokenStream; + use quote::{ToTokens, TokenStreamExt}; + + use crate::print::TokensOrDefault; + + impl ToTokens for Variant { + fn to_tokens(&self, tokens: &mut TokenStream) { + tokens.append_all(&self.attrs); + self.ident.to_tokens(tokens); + self.fields.to_tokens(tokens); + if let Some((eq_token, disc)) = &self.discriminant { + eq_token.to_tokens(tokens); + disc.to_tokens(tokens); + } + } + } + + impl ToTokens for FieldsNamed { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.brace_token.surround(tokens, |tokens| { + self.named.to_tokens(tokens); + }); + } + } + + impl ToTokens for FieldsUnnamed { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.paren_token.surround(tokens, |tokens| { + self.unnamed.to_tokens(tokens); + }); + } + } + + impl ToTokens for Field { + fn to_tokens(&self, tokens: &mut TokenStream) { + tokens.append_all(&self.attrs); + self.vis.to_tokens(tokens); + if let Some(ident) = &self.ident { + ident.to_tokens(tokens); + TokensOrDefault(&self.colon_token).to_tokens(tokens); + } + self.ty.to_tokens(tokens); + } + } + + impl ToTokens for VisPublic { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.pub_token.to_tokens(tokens) + } + } + + impl ToTokens for VisCrate { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.crate_token.to_tokens(tokens); + } + } + + impl ToTokens for VisRestricted { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.pub_token.to_tokens(tokens); + self.paren_token.surround(tokens, |tokens| { + // TODO: If we have a path which is not "self" or "super" or + // "crate", automatically add the "in" token. + self.in_token.to_tokens(tokens); + self.path.to_tokens(tokens); + }); + } + } +} diff --git a/syn/src/derive.rs b/syn/src/derive.rs new file mode 100644 index 0000000..8cb9cf7 --- /dev/null +++ b/syn/src/derive.rs @@ -0,0 +1,273 @@ +use super::*; +use crate::punctuated::Punctuated; + +ast_struct! { + /// Data structure sent to a `proc_macro_derive` macro. + /// + /// *This type is available if Syn is built with the `"derive"` feature.* + pub struct DeriveInput { + /// Attributes tagged on the whole struct or enum. + pub attrs: Vec, + + /// Visibility of the struct or enum. + pub vis: Visibility, + + /// Name of the struct or enum. + pub ident: Ident, + + /// Generics required to complete the definition. + pub generics: Generics, + + /// Data within the struct or enum. + pub data: Data, + } +} + +ast_enum_of_structs! { + /// The storage of a struct, enum or union data structure. + /// + /// *This type is available if Syn is built with the `"derive"` feature.* + /// + /// # Syntax tree enum + /// + /// This type is a [syntax tree enum]. + /// + /// [syntax tree enum]: enum.Expr.html#syntax-tree-enums + // + // TODO: change syntax-tree-enum link to an intra rustdoc link, currently + // blocked on https://github.com/rust-lang/rust/issues/62833 + pub enum Data { + /// A struct input to a `proc_macro_derive` macro. + Struct(DataStruct), + + /// An enum input to a `proc_macro_derive` macro. + Enum(DataEnum), + + /// An untagged union input to a `proc_macro_derive` macro. + Union(DataUnion), + } + + do_not_generate_to_tokens +} + +ast_struct! { + /// A struct input to a `proc_macro_derive` macro. + /// + /// *This type is available if Syn is built with the `"derive"` + /// feature.* + pub struct DataStruct { + pub struct_token: Token![struct], + pub fields: Fields, + pub semi_token: Option, + } +} + +ast_struct! { + /// An enum input to a `proc_macro_derive` macro. + /// + /// *This type is available if Syn is built with the `"derive"` + /// feature.* + pub struct DataEnum { + pub enum_token: Token![enum], + pub brace_token: token::Brace, + pub variants: Punctuated, + } +} + +ast_struct! { + /// An untagged union input to a `proc_macro_derive` macro. + /// + /// *This type is available if Syn is built with the `"derive"` + /// feature.* + pub struct DataUnion { + pub union_token: Token![union], + pub fields: FieldsNamed, + } +} + +#[cfg(feature = "parsing")] +pub mod parsing { + use super::*; + + use crate::parse::{Parse, ParseStream, Result}; + + impl Parse for DeriveInput { + fn parse(input: ParseStream) -> Result { + let attrs = input.call(Attribute::parse_outer)?; + let vis = input.parse::()?; + + let lookahead = input.lookahead1(); + if lookahead.peek(Token![struct]) { + let struct_token = input.parse::()?; + let ident = input.parse::()?; + let generics = input.parse::()?; + let (where_clause, fields, semi) = data_struct(input)?; + Ok(DeriveInput { + attrs, + vis, + ident, + generics: Generics { + where_clause, + ..generics + }, + data: Data::Struct(DataStruct { + struct_token, + fields, + semi_token: semi, + }), + }) + } else if lookahead.peek(Token![enum]) { + let enum_token = input.parse::()?; + let ident = input.parse::()?; + let generics = input.parse::()?; + let (where_clause, brace, variants) = data_enum(input)?; + Ok(DeriveInput { + attrs, + vis, + ident, + generics: Generics { + where_clause, + ..generics + }, + data: Data::Enum(DataEnum { + enum_token, + brace_token: brace, + variants, + }), + }) + } else if lookahead.peek(Token![union]) { + let union_token = input.parse::()?; + let ident = input.parse::()?; + let generics = input.parse::()?; + let (where_clause, fields) = data_union(input)?; + Ok(DeriveInput { + attrs, + vis, + ident, + generics: Generics { + where_clause, + ..generics + }, + data: Data::Union(DataUnion { + union_token, + fields, + }), + }) + } else { + Err(lookahead.error()) + } + } + } + + pub fn data_struct( + input: ParseStream, + ) -> Result<(Option, Fields, Option)> { + let mut lookahead = input.lookahead1(); + let mut where_clause = None; + if lookahead.peek(Token![where]) { + where_clause = Some(input.parse()?); + lookahead = input.lookahead1(); + } + + if where_clause.is_none() && lookahead.peek(token::Paren) { + let fields = input.parse()?; + + lookahead = input.lookahead1(); + if lookahead.peek(Token![where]) { + where_clause = Some(input.parse()?); + lookahead = input.lookahead1(); + } + + if lookahead.peek(Token![;]) { + let semi = input.parse()?; + Ok((where_clause, Fields::Unnamed(fields), Some(semi))) + } else { + Err(lookahead.error()) + } + } else if lookahead.peek(token::Brace) { + let fields = input.parse()?; + Ok((where_clause, Fields::Named(fields), None)) + } else if lookahead.peek(Token![;]) { + let semi = input.parse()?; + Ok((where_clause, Fields::Unit, Some(semi))) + } else { + Err(lookahead.error()) + } + } + + pub fn data_enum( + input: ParseStream, + ) -> Result<( + Option, + token::Brace, + Punctuated, + )> { + let where_clause = input.parse()?; + + let content; + let brace = braced!(content in input); + let variants = content.parse_terminated(Variant::parse)?; + + Ok((where_clause, brace, variants)) + } + + pub fn data_union(input: ParseStream) -> Result<(Option, FieldsNamed)> { + let where_clause = input.parse()?; + let fields = input.parse()?; + Ok((where_clause, fields)) + } +} + +#[cfg(feature = "printing")] +mod printing { + use super::*; + + use proc_macro2::TokenStream; + use quote::ToTokens; + + use crate::attr::FilterAttrs; + use crate::print::TokensOrDefault; + + impl ToTokens for DeriveInput { + fn to_tokens(&self, tokens: &mut TokenStream) { + for attr in self.attrs.outer() { + attr.to_tokens(tokens); + } + self.vis.to_tokens(tokens); + match &self.data { + Data::Struct(d) => d.struct_token.to_tokens(tokens), + Data::Enum(d) => d.enum_token.to_tokens(tokens), + Data::Union(d) => d.union_token.to_tokens(tokens), + } + self.ident.to_tokens(tokens); + self.generics.to_tokens(tokens); + match &self.data { + Data::Struct(data) => match &data.fields { + Fields::Named(fields) => { + self.generics.where_clause.to_tokens(tokens); + fields.to_tokens(tokens); + } + Fields::Unnamed(fields) => { + fields.to_tokens(tokens); + self.generics.where_clause.to_tokens(tokens); + TokensOrDefault(&data.semi_token).to_tokens(tokens); + } + Fields::Unit => { + self.generics.where_clause.to_tokens(tokens); + TokensOrDefault(&data.semi_token).to_tokens(tokens); + } + }, + Data::Enum(data) => { + self.generics.where_clause.to_tokens(tokens); + data.brace_token.surround(tokens, |tokens| { + data.variants.to_tokens(tokens); + }); + } + Data::Union(data) => { + self.generics.where_clause.to_tokens(tokens); + data.fields.to_tokens(tokens); + } + } + } + } +} diff --git a/syn/src/discouraged.rs b/syn/src/discouraged.rs new file mode 100644 index 0000000..29d1006 --- /dev/null +++ b/syn/src/discouraged.rs @@ -0,0 +1,195 @@ +//! Extensions to the parsing API with niche applicability. + +use super::*; + +/// Extensions to the `ParseStream` API to support speculative parsing. +pub trait Speculative { + /// Advance this parse stream to the position of a forked parse stream. + /// + /// This is the opposite operation to [`ParseStream::fork`]. You can fork a + /// parse stream, perform some speculative parsing, then join the original + /// stream to the fork to "commit" the parsing from the fork to the main + /// stream. + /// + /// If you can avoid doing this, you should, as it limits the ability to + /// generate useful errors. That said, it is often the only way to parse + /// syntax of the form `A* B*` for arbitrary syntax `A` and `B`. The problem + /// is that when the fork fails to parse an `A`, it's impossible to tell + /// whether that was because of a syntax error and the user meant to provide + /// an `A`, or that the `A`s are finished and its time to start parsing + /// `B`s. Use with care. + /// + /// Also note that if `A` is a subset of `B`, `A* B*` can be parsed by + /// parsing `B*` and removing the leading members of `A` from the + /// repetition, bypassing the need to involve the downsides associated with + /// speculative parsing. + /// + /// [`ParseStream::fork`]: ParseBuffer::fork + /// + /// # Example + /// + /// There has been chatter about the possibility of making the colons in the + /// turbofish syntax like `path::to::` no longer required by accepting + /// `path::to` in expression position. Specifically, according to [RFC + /// 2544], [`PathSegment`] parsing should always try to consume a following + /// `<` token as the start of generic arguments, and reset to the `<` if + /// that fails (e.g. the token is acting as a less-than operator). + /// + /// This is the exact kind of parsing behavior which requires the "fork, + /// try, commit" behavior that [`ParseStream::fork`] discourages. With + /// `advance_to`, we can avoid having to parse the speculatively parsed + /// content a second time. + /// + /// This change in behavior can be implemented in syn by replacing just the + /// `Parse` implementation for `PathSegment`: + /// + /// ``` + /// # use syn::ext::IdentExt; + /// use syn::parse::discouraged::Speculative; + /// # use syn::parse::{Parse, ParseStream}; + /// # use syn::{Ident, PathArguments, Result, Token}; + /// + /// pub struct PathSegment { + /// pub ident: Ident, + /// pub arguments: PathArguments, + /// } + /// # + /// # impl From for PathSegment + /// # where + /// # T: Into, + /// # { + /// # fn from(ident: T) -> Self { + /// # PathSegment { + /// # ident: ident.into(), + /// # arguments: PathArguments::None, + /// # } + /// # } + /// # } + /// + /// impl Parse for PathSegment { + /// fn parse(input: ParseStream) -> Result { + /// if input.peek(Token![super]) + /// || input.peek(Token![self]) + /// || input.peek(Token![Self]) + /// || input.peek(Token![crate]) + /// || input.peek(Token![extern]) + /// { + /// let ident = input.call(Ident::parse_any)?; + /// return Ok(PathSegment::from(ident)); + /// } + /// + /// let ident = input.parse()?; + /// if input.peek(Token![::]) && input.peek3(Token![<]) { + /// return Ok(PathSegment { + /// ident, + /// arguments: PathArguments::AngleBracketed(input.parse()?), + /// }); + /// } + /// if input.peek(Token![<]) && !input.peek(Token![<=]) { + /// let fork = input.fork(); + /// if let Ok(arguments) = fork.parse() { + /// input.advance_to(&fork); + /// return Ok(PathSegment { + /// ident, + /// arguments: PathArguments::AngleBracketed(arguments), + /// }); + /// } + /// } + /// Ok(PathSegment::from(ident)) + /// } + /// } + /// + /// # syn::parse_str::("a").unwrap(); + /// ``` + /// + /// # Drawbacks + /// + /// The main drawback of this style of speculative parsing is in error + /// presentation. Even if the lookahead is the "correct" parse, the error + /// that is shown is that of the "fallback" parse. To use the same example + /// as the turbofish above, take the following unfinished "turbofish": + /// + /// ```text + /// let _ = f<&'a fn(), for<'a> serde::>(); + /// ``` + /// + /// If this is parsed as generic arguments, we can provide the error message + /// + /// ```text + /// error: expected identifier + /// --> src.rs:L:C + /// | + /// L | let _ = f<&'a fn(), for<'a> serde::>(); + /// | ^ + /// ``` + /// + /// but if parsed using the above speculative parsing, it falls back to + /// assuming that the `<` is a less-than when it fails to parse the generic + /// arguments, and tries to interpret the `&'a` as the start of a labelled + /// loop, resulting in the much less helpful error + /// + /// ```text + /// error: expected `:` + /// --> src.rs:L:C + /// | + /// L | let _ = f<&'a fn(), for<'a> serde::>(); + /// | ^^ + /// ``` + /// + /// This can be mitigated with various heuristics (two examples: show both + /// forks' parse errors, or show the one that consumed more tokens), but + /// when you can control the grammar, sticking to something that can be + /// parsed LL(3) and without the LL(*) speculative parsing this makes + /// possible, displaying reasonable errors becomes much more simple. + /// + /// [RFC 2544]: https://github.com/rust-lang/rfcs/pull/2544 + /// [`PathSegment`]: crate::PathSegment + /// + /// # Performance + /// + /// This method performs a cheap fixed amount of work that does not depend + /// on how far apart the two streams are positioned. + /// + /// # Panics + /// + /// The forked stream in the argument of `advance_to` must have been + /// obtained by forking `self`. Attempting to advance to any other stream + /// will cause a panic. + fn advance_to(&self, fork: &Self); +} + +impl<'a> Speculative for ParseBuffer<'a> { + fn advance_to(&self, fork: &Self) { + if !crate::buffer::same_scope(self.cursor(), fork.cursor()) { + panic!("Fork was not derived from the advancing parse stream"); + } + + let (self_unexp, self_sp) = inner_unexpected(self); + let (fork_unexp, fork_sp) = inner_unexpected(fork); + if !Rc::ptr_eq(&self_unexp, &fork_unexp) { + match (fork_sp, self_sp) { + // Unexpected set on the fork, but not on `self`, copy it over. + (Some(span), None) => { + self_unexp.set(Unexpected::Some(span)); + } + // Unexpected unset. Use chain to propagate errors from fork. + (None, None) => { + fork_unexp.set(Unexpected::Chain(self_unexp)); + + // Ensure toplevel 'unexpected' tokens from the fork don't + // bubble up the chain by replacing the root `unexpected` + // pointer, only 'unexpected' tokens from existing group + // parsers should bubble. + fork.unexpected + .set(Some(Rc::new(Cell::new(Unexpected::None)))); + } + // Unexpected has been set on `self`. No changes needed. + (_, Some(_)) => {} + } + } + + // See comment on `cell` in the struct definition. + self.cell + .set(unsafe { mem::transmute::>(fork.cursor()) }) + } +} diff --git a/syn/src/error.rs b/syn/src/error.rs new file mode 100644 index 0000000..146d652 --- /dev/null +++ b/syn/src/error.rs @@ -0,0 +1,357 @@ +use std; +use std::fmt::{self, Debug, Display}; +use std::iter::FromIterator; +use std::slice; +use std::vec; + +use proc_macro2::{ + Delimiter, Group, Ident, LexError, Literal, Punct, Spacing, Span, TokenStream, TokenTree, +}; +#[cfg(feature = "printing")] +use quote::ToTokens; + +#[cfg(feature = "parsing")] +use crate::buffer::Cursor; +use crate::thread::ThreadBound; + +/// The result of a Syn parser. +pub type Result = std::result::Result; + +/// Error returned when a Syn parser cannot parse the input tokens. +/// +/// # Error reporting in proc macros +/// +/// The correct way to report errors back to the compiler from a procedural +/// macro is by emitting an appropriately spanned invocation of +/// [`compile_error!`] in the generated code. This produces a better diagnostic +/// message than simply panicking the macro. +/// +/// [`compile_error!`]: https://doc.rust-lang.org/std/macro.compile_error.html +/// +/// When parsing macro input, the [`parse_macro_input!`] macro handles the +/// conversion to `compile_error!` automatically. +/// +/// ``` +/// extern crate proc_macro; +/// +/// use proc_macro::TokenStream; +/// use syn::{parse_macro_input, AttributeArgs, ItemFn}; +/// +/// # const IGNORE: &str = stringify! { +/// #[proc_macro_attribute] +/// # }; +/// pub fn my_attr(args: TokenStream, input: TokenStream) -> TokenStream { +/// let args = parse_macro_input!(args as AttributeArgs); +/// let input = parse_macro_input!(input as ItemFn); +/// +/// /* ... */ +/// # TokenStream::new() +/// } +/// ``` +/// +/// For errors that arise later than the initial parsing stage, the +/// [`.to_compile_error()`] method can be used to perform an explicit conversion +/// to `compile_error!`. +/// +/// [`.to_compile_error()`]: Error::to_compile_error +/// +/// ``` +/// # extern crate proc_macro; +/// # +/// # use proc_macro::TokenStream; +/// # use syn::{parse_macro_input, DeriveInput}; +/// # +/// # const IGNORE: &str = stringify! { +/// #[proc_macro_derive(MyDerive)] +/// # }; +/// pub fn my_derive(input: TokenStream) -> TokenStream { +/// let input = parse_macro_input!(input as DeriveInput); +/// +/// // fn(DeriveInput) -> syn::Result +/// expand::my_derive(input) +/// .unwrap_or_else(|err| err.to_compile_error()) +/// .into() +/// } +/// # +/// # mod expand { +/// # use proc_macro2::TokenStream; +/// # use syn::{DeriveInput, Result}; +/// # +/// # pub fn my_derive(input: DeriveInput) -> Result { +/// # unimplemented!() +/// # } +/// # } +/// ``` +#[derive(Clone)] +pub struct Error { + messages: Vec, +} + +struct ErrorMessage { + // Span is implemented as an index into a thread-local interner to keep the + // size small. It is not safe to access from a different thread. We want + // errors to be Send and Sync to play nicely with the Failure crate, so pin + // the span we're given to its original thread and assume it is + // Span::call_site if accessed from any other thread. + start_span: ThreadBound, + end_span: ThreadBound, + message: String, +} + +#[cfg(test)] +struct _Test +where + Error: Send + Sync; + +impl Error { + /// Usually the [`ParseStream::error`] method will be used instead, which + /// automatically uses the correct span from the current position of the + /// parse stream. + /// + /// Use `Error::new` when the error needs to be triggered on some span other + /// than where the parse stream is currently positioned. + /// + /// [`ParseStream::error`]: crate::parse::ParseBuffer::error + /// + /// # Example + /// + /// ``` + /// use syn::{Error, Ident, LitStr, Result, Token}; + /// use syn::parse::ParseStream; + /// + /// // Parses input that looks like `name = "string"` where the key must be + /// // the identifier `name` and the value may be any string literal. + /// // Returns the string literal. + /// fn parse_name(input: ParseStream) -> Result { + /// let name_token: Ident = input.parse()?; + /// if name_token != "name" { + /// // Trigger an error not on the current position of the stream, + /// // but on the position of the unexpected identifier. + /// return Err(Error::new(name_token.span(), "expected `name`")); + /// } + /// input.parse::()?; + /// let s: LitStr = input.parse()?; + /// Ok(s) + /// } + /// ``` + pub fn new(span: Span, message: T) -> Self { + Error { + messages: vec![ErrorMessage { + start_span: ThreadBound::new(span), + end_span: ThreadBound::new(span), + message: message.to_string(), + }], + } + } + + /// Creates an error with the specified message spanning the given syntax + /// tree node. + /// + /// Unlike the `Error::new` constructor, this constructor takes an argument + /// `tokens` which is a syntax tree node. This allows the resulting `Error` + /// to attempt to span all tokens inside of `tokens`. While you would + /// typically be able to use the `Spanned` trait with the above `Error::new` + /// constructor, implementation limitations today mean that + /// `Error::new_spanned` may provide a higher-quality error message on + /// stable Rust. + /// + /// When in doubt it's recommended to stick to `Error::new` (or + /// `ParseStream::error`)! + #[cfg(feature = "printing")] + pub fn new_spanned(tokens: T, message: U) -> Self { + let mut iter = tokens.into_token_stream().into_iter(); + let start = iter.next().map_or_else(Span::call_site, |t| t.span()); + let end = iter.last().map_or(start, |t| t.span()); + Error { + messages: vec![ErrorMessage { + start_span: ThreadBound::new(start), + end_span: ThreadBound::new(end), + message: message.to_string(), + }], + } + } + + /// The source location of the error. + /// + /// Spans are not thread-safe so this function returns `Span::call_site()` + /// if called from a different thread than the one on which the `Error` was + /// originally created. + pub fn span(&self) -> Span { + let start = match self.messages[0].start_span.get() { + Some(span) => *span, + None => return Span::call_site(), + }; + let end = match self.messages[0].end_span.get() { + Some(span) => *span, + None => return Span::call_site(), + }; + start.join(end).unwrap_or(start) + } + + /// Render the error as an invocation of [`compile_error!`]. + /// + /// The [`parse_macro_input!`] macro provides a convenient way to invoke + /// this method correctly in a procedural macro. + /// + /// [`compile_error!`]: https://doc.rust-lang.org/std/macro.compile_error.html + pub fn to_compile_error(&self) -> TokenStream { + self.messages + .iter() + .map(ErrorMessage::to_compile_error) + .collect() + } + + /// Add another error message to self such that when `to_compile_error()` is + /// called, both errors will be emitted together. + pub fn combine(&mut self, another: Error) { + self.messages.extend(another.messages) + } +} + +impl ErrorMessage { + fn to_compile_error(&self) -> TokenStream { + let start = self + .start_span + .get() + .cloned() + .unwrap_or_else(Span::call_site); + let end = self.end_span.get().cloned().unwrap_or_else(Span::call_site); + + // compile_error!($message) + TokenStream::from_iter(vec![ + TokenTree::Ident(Ident::new("compile_error", start)), + TokenTree::Punct({ + let mut punct = Punct::new('!', Spacing::Alone); + punct.set_span(start); + punct + }), + TokenTree::Group({ + let mut group = Group::new(Delimiter::Brace, { + TokenStream::from_iter(vec![TokenTree::Literal({ + let mut string = Literal::string(&self.message); + string.set_span(end); + string + })]) + }); + group.set_span(end); + group + }), + ]) + } +} + +#[cfg(feature = "parsing")] +pub fn new_at(scope: Span, cursor: Cursor, message: T) -> Error { + if cursor.eof() { + Error::new(scope, format!("unexpected end of input, {}", message)) + } else { + let span = crate::buffer::open_span_of_group(cursor); + Error::new(span, message) + } +} + +impl Debug for Error { + fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + if self.messages.len() == 1 { + formatter + .debug_tuple("Error") + .field(&self.messages[0]) + .finish() + } else { + formatter + .debug_tuple("Error") + .field(&self.messages) + .finish() + } + } +} + +impl Debug for ErrorMessage { + fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + Debug::fmt(&self.message, formatter) + } +} + +impl Display for Error { + fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + formatter.write_str(&self.messages[0].message) + } +} + +impl Clone for ErrorMessage { + fn clone(&self) -> Self { + let start = self + .start_span + .get() + .cloned() + .unwrap_or_else(Span::call_site); + let end = self.end_span.get().cloned().unwrap_or_else(Span::call_site); + ErrorMessage { + start_span: ThreadBound::new(start), + end_span: ThreadBound::new(end), + message: self.message.clone(), + } + } +} + +impl std::error::Error for Error { + fn description(&self) -> &str { + "parse error" + } +} + +impl From for Error { + fn from(err: LexError) -> Self { + Error::new(Span::call_site(), format!("{:?}", err)) + } +} + +impl IntoIterator for Error { + type Item = Error; + type IntoIter = IntoIter; + + fn into_iter(self) -> Self::IntoIter { + IntoIter { + messages: self.messages.into_iter(), + } + } +} + +pub struct IntoIter { + messages: vec::IntoIter, +} + +impl Iterator for IntoIter { + type Item = Error; + + fn next(&mut self) -> Option { + Some(Error { + messages: vec![self.messages.next()?], + }) + } +} + +impl<'a> IntoIterator for &'a Error { + type Item = Error; + type IntoIter = Iter<'a>; + + fn into_iter(self) -> Self::IntoIter { + Iter { + messages: self.messages.iter(), + } + } +} + +pub struct Iter<'a> { + messages: slice::Iter<'a, ErrorMessage>, +} + +impl<'a> Iterator for Iter<'a> { + type Item = Error; + + fn next(&mut self) -> Option { + Some(Error { + messages: vec![self.messages.next()?.clone()], + }) + } +} diff --git a/syn/src/export.rs b/syn/src/export.rs new file mode 100644 index 0000000..37dc467 --- /dev/null +++ b/syn/src/export.rs @@ -0,0 +1,35 @@ +pub use std::clone::Clone; +pub use std::cmp::{Eq, PartialEq}; +pub use std::convert::From; +pub use std::default::Default; +pub use std::fmt::{self, Debug, Formatter}; +pub use std::hash::{Hash, Hasher}; +pub use std::marker::Copy; +pub use std::option::Option::{None, Some}; +pub use std::result::Result::{Err, Ok}; + +#[cfg(feature = "printing")] +pub extern crate quote; + +pub use proc_macro2::{Span, TokenStream as TokenStream2}; + +pub use crate::span::IntoSpans; + +#[cfg(all( + not(all(target_arch = "wasm32", any(target_os = "unknown", target_os = "wasi"))), + feature = "proc-macro" +))] +pub use proc_macro::TokenStream; + +#[cfg(feature = "printing")] +pub use quote::{ToTokens, TokenStreamExt}; + +#[allow(non_camel_case_types)] +pub type bool = help::Bool; +#[allow(non_camel_case_types)] +pub type str = help::Str; + +mod help { + pub type Bool = bool; + pub type Str = str; +} diff --git a/syn/src/expr.rs b/syn/src/expr.rs new file mode 100644 index 0000000..603dc32 --- /dev/null +++ b/syn/src/expr.rs @@ -0,0 +1,3236 @@ +use super::*; +use crate::punctuated::Punctuated; +#[cfg(feature = "extra-traits")] +use crate::tt::TokenStreamHelper; +use proc_macro2::{Span, TokenStream}; +#[cfg(feature = "printing")] +use quote::IdentFragment; +#[cfg(feature = "printing")] +use std::fmt::{self, Display}; +use std::hash::{Hash, Hasher}; +#[cfg(all(feature = "parsing", feature = "full"))] +use std::mem; + +ast_enum_of_structs! { + /// A Rust expression. + /// + /// *This type is available if Syn is built with the `"derive"` or `"full"` + /// feature.* + /// + /// # Syntax tree enums + /// + /// This type is a syntax tree enum. In Syn this and other syntax tree enums + /// are designed to be traversed using the following rebinding idiom. + /// + /// ``` + /// # use syn::Expr; + /// # + /// # fn example(expr: Expr) { + /// # const IGNORE: &str = stringify! { + /// let expr: Expr = /* ... */; + /// # }; + /// match expr { + /// Expr::MethodCall(expr) => { + /// /* ... */ + /// } + /// Expr::Cast(expr) => { + /// /* ... */ + /// } + /// Expr::If(expr) => { + /// /* ... */ + /// } + /// + /// /* ... */ + /// # _ => {} + /// # } + /// # } + /// ``` + /// + /// We begin with a variable `expr` of type `Expr` that has no fields + /// (because it is an enum), and by matching on it and rebinding a variable + /// with the same name `expr` we effectively imbue our variable with all of + /// the data fields provided by the variant that it turned out to be. So for + /// example above if we ended up in the `MethodCall` case then we get to use + /// `expr.receiver`, `expr.args` etc; if we ended up in the `If` case we get + /// to use `expr.cond`, `expr.then_branch`, `expr.else_branch`. + /// + /// This approach avoids repeating the variant names twice on every line. + /// + /// ``` + /// # use syn::{Expr, ExprMethodCall}; + /// # + /// # fn example(expr: Expr) { + /// // Repetitive; recommend not doing this. + /// match expr { + /// Expr::MethodCall(ExprMethodCall { method, args, .. }) => { + /// # } + /// # _ => {} + /// # } + /// # } + /// ``` + /// + /// In general, the name to which a syntax tree enum variant is bound should + /// be a suitable name for the complete syntax tree enum type. + /// + /// ``` + /// # use syn::{Expr, ExprField}; + /// # + /// # fn example(discriminant: ExprField) { + /// // Binding is called `base` which is the name I would use if I were + /// // assigning `*discriminant.base` without an `if let`. + /// if let Expr::Tuple(base) = *discriminant.base { + /// # } + /// # } + /// ``` + /// + /// A sign that you may not be choosing the right variable names is if you + /// see names getting repeated in your code, like accessing + /// `receiver.receiver` or `pat.pat` or `cond.cond`. + pub enum Expr #manual_extra_traits { + /// A slice literal expression: `[a, b, c, d]`. + Array(ExprArray), + + /// An assignment expression: `a = compute()`. + Assign(ExprAssign), + + /// A compound assignment expression: `counter += 1`. + AssignOp(ExprAssignOp), + + /// An async block: `async { ... }`. + Async(ExprAsync), + + /// An await expression: `fut.await`. + Await(ExprAwait), + + /// A binary operation: `a + b`, `a * b`. + Binary(ExprBinary), + + /// A blocked scope: `{ ... }`. + Block(ExprBlock), + + /// A box expression: `box f`. + Box(ExprBox), + + /// A `break`, with an optional label to break and an optional + /// expression. + Break(ExprBreak), + + /// A function call expression: `invoke(a, b)`. + Call(ExprCall), + + /// A cast expression: `foo as f64`. + Cast(ExprCast), + + /// A closure expression: `|a, b| a + b`. + Closure(ExprClosure), + + /// A `continue`, with an optional label. + Continue(ExprContinue), + + /// Access of a named struct field (`obj.k`) or unnamed tuple struct + /// field (`obj.0`). + Field(ExprField), + + /// A for loop: `for pat in expr { ... }`. + ForLoop(ExprForLoop), + + /// An expression contained within invisible delimiters. + /// + /// This variant is important for faithfully representing the precedence + /// of expressions and is related to `None`-delimited spans in a + /// `TokenStream`. + Group(ExprGroup), + + /// An `if` expression with an optional `else` block: `if expr { ... } + /// else { ... }`. + /// + /// The `else` branch expression may only be an `If` or `Block` + /// expression, not any of the other types of expression. + If(ExprIf), + + /// A square bracketed indexing expression: `vector[2]`. + Index(ExprIndex), + + /// A `let` guard: `let Some(x) = opt`. + Let(ExprLet), + + /// A literal in place of an expression: `1`, `"foo"`. + Lit(ExprLit), + + /// Conditionless loop: `loop { ... }`. + Loop(ExprLoop), + + /// A macro invocation expression: `format!("{}", q)`. + Macro(ExprMacro), + + /// A `match` expression: `match n { Some(n) => {}, None => {} }`. + Match(ExprMatch), + + /// A method call expression: `x.foo::(a, b)`. + MethodCall(ExprMethodCall), + + /// A parenthesized expression: `(a + b)`. + Paren(ExprParen), + + /// A path like `std::mem::replace` possibly containing generic + /// parameters and a qualified self-type. + /// + /// A plain identifier like `x` is a path of length 1. + Path(ExprPath), + + /// A range expression: `1..2`, `1..`, `..2`, `1..=2`, `..=2`. + Range(ExprRange), + + /// A referencing operation: `&a` or `&mut a`. + Reference(ExprReference), + + /// An array literal constructed from one repeated element: `[0u8; N]`. + Repeat(ExprRepeat), + + /// A `return`, with an optional value to be returned. + Return(ExprReturn), + + /// A struct literal expression: `Point { x: 1, y: 1 }`. + /// + /// The `rest` provides the value of the remaining fields as in `S { a: + /// 1, b: 1, ..rest }`. + Struct(ExprStruct), + + /// A try-expression: `expr?`. + Try(ExprTry), + + /// A try block: `try { ... }`. + TryBlock(ExprTryBlock), + + /// A tuple expression: `(a, b, c, d)`. + Tuple(ExprTuple), + + /// A type ascription expression: `foo: f64`. + Type(ExprType), + + /// A unary operation: `!x`, `*x`. + Unary(ExprUnary), + + /// An unsafe block: `unsafe { ... }`. + Unsafe(ExprUnsafe), + + /// Tokens in expression position not interpreted by Syn. + Verbatim(TokenStream), + + /// A while loop: `while expr { ... }`. + While(ExprWhile), + + /// A yield expression: `yield expr`. + Yield(ExprYield), + + #[doc(hidden)] + __Nonexhaustive, + } +} + +ast_struct! { + /// A slice literal expression: `[a, b, c, d]`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprArray #full { + pub attrs: Vec, + pub bracket_token: token::Bracket, + pub elems: Punctuated, + } +} + +ast_struct! { + /// An assignment expression: `a = compute()`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprAssign #full { + pub attrs: Vec, + pub left: Box, + pub eq_token: Token![=], + pub right: Box, + } +} + +ast_struct! { + /// A compound assignment expression: `counter += 1`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprAssignOp #full { + pub attrs: Vec, + pub left: Box, + pub op: BinOp, + pub right: Box, + } +} + +ast_struct! { + /// An async block: `async { ... }`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprAsync #full { + pub attrs: Vec, + pub async_token: Token![async], + pub capture: Option, + pub block: Block, + } +} + +ast_struct! { + /// An await expression: `fut.await`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprAwait #full { + pub attrs: Vec, + pub base: Box, + pub dot_token: Token![.], + pub await_token: token::Await, + } +} + +ast_struct! { + /// A binary operation: `a + b`, `a * b`. + /// + /// *This type is available if Syn is built with the `"derive"` or + /// `"full"` feature.* + pub struct ExprBinary { + pub attrs: Vec, + pub left: Box, + pub op: BinOp, + pub right: Box, + } +} + +ast_struct! { + /// A blocked scope: `{ ... }`. + /// + /// *This type is available if Syn is built with the `"full"` feature.* + pub struct ExprBlock #full { + pub attrs: Vec, + pub label: Option