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Diffstat (limited to 'third_party/rust/syn/src/path.rs')
| -rw-r--r-- | third_party/rust/syn/src/path.rs | 854 |
1 files changed, 854 insertions, 0 deletions
diff --git a/third_party/rust/syn/src/path.rs b/third_party/rust/syn/src/path.rs new file mode 100644 index 0000000000..6cdb43ac54 --- /dev/null +++ b/third_party/rust/syn/src/path.rs @@ -0,0 +1,854 @@ +use super::*; +use crate::punctuated::Punctuated; + +ast_struct! { + /// A path at which a named item is exported (e.g. `std::collections::HashMap`). + /// + /// *This type is available only if Syn is built with the `"derive"` or `"full"` + /// feature.* + #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct Path { + pub leading_colon: Option<Token![::]>, + pub segments: Punctuated<PathSegment, Token![::]>, + } +} + +impl<T> From<T> for Path +where + T: Into<PathSegment>, +{ + fn from(segment: T) -> Self { + let mut path = Path { + leading_colon: None, + segments: Punctuated::new(), + }; + path.segments.push_value(segment.into()); + path + } +} + +ast_struct! { + /// A segment of a path together with any path arguments on that segment. + /// + /// *This type is available only if Syn is built with the `"derive"` or `"full"` + /// feature.* + #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct PathSegment { + pub ident: Ident, + pub arguments: PathArguments, + } +} + +impl<T> From<T> for PathSegment +where + T: Into<Ident>, +{ + fn from(ident: T) -> Self { + PathSegment { + ident: ident.into(), + arguments: PathArguments::None, + } + } +} + +ast_enum! { + /// Angle bracketed or parenthesized arguments of a path segment. + /// + /// *This type is available only if Syn is built with the `"derive"` or `"full"` + /// feature.* + /// + /// ## Angle bracketed + /// + /// The `<'a, T>` in `std::slice::iter<'a, T>`. + /// + /// ## Parenthesized + /// + /// The `(A, B) -> C` in `Fn(A, B) -> C`. + #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))] + pub enum PathArguments { + None, + /// The `<'a, T>` in `std::slice::iter<'a, T>`. + AngleBracketed(AngleBracketedGenericArguments), + /// The `(A, B) -> C` in `Fn(A, B) -> C`. + Parenthesized(ParenthesizedGenericArguments), + } +} + +impl Default for PathArguments { + fn default() -> Self { + PathArguments::None + } +} + +impl PathArguments { + pub fn is_empty(&self) -> bool { + match self { + PathArguments::None => true, + PathArguments::AngleBracketed(bracketed) => bracketed.args.is_empty(), + PathArguments::Parenthesized(_) => false, + } + } + + pub fn is_none(&self) -> bool { + match self { + PathArguments::None => true, + PathArguments::AngleBracketed(_) | PathArguments::Parenthesized(_) => false, + } + } +} + +ast_enum! { + /// An individual generic argument, like `'a`, `T`, or `Item = T`. + /// + /// *This type is available only if Syn is built with the `"derive"` or `"full"` + /// feature.* + #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))] + pub enum GenericArgument { + /// A lifetime argument. + Lifetime(Lifetime), + /// A type argument. + Type(Type), + /// A const expression. Must be inside of a block. + /// + /// NOTE: Identity expressions are represented as Type arguments, as + /// they are indistinguishable syntactically. + Const(Expr), + /// A binding (equality constraint) on an associated type: the `Item = + /// u8` in `Iterator<Item = u8>`. + Binding(Binding), + /// An associated type bound: `Iterator<Item: Display>`. + Constraint(Constraint), + } +} + +ast_struct! { + /// Angle bracketed arguments of a path segment: the `<K, V>` in `HashMap<K, + /// V>`. + /// + /// *This type is available only if Syn is built with the `"derive"` or `"full"` + /// feature.* + #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct AngleBracketedGenericArguments { + pub colon2_token: Option<Token![::]>, + pub lt_token: Token![<], + pub args: Punctuated<GenericArgument, Token![,]>, + pub gt_token: Token![>], + } +} + +ast_struct! { + /// A binding (equality constraint) on an associated type: `Item = u8`. + /// + /// *This type is available only if Syn is built with the `"derive"` or `"full"` + /// feature.* + #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct Binding { + pub ident: Ident, + pub eq_token: Token![=], + pub ty: Type, + } +} + +ast_struct! { + /// An associated type bound: `Iterator<Item: Display>`. + /// + /// *This type is available only if Syn is built with the `"derive"` or `"full"` + /// feature.* + #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct Constraint { + pub ident: Ident, + pub colon_token: Token![:], + pub bounds: Punctuated<TypeParamBound, Token![+]>, + } +} + +ast_struct! { + /// Arguments of a function path segment: the `(A, B) -> C` in `Fn(A,B) -> + /// C`. + /// + /// *This type is available only if Syn is built with the `"derive"` or `"full"` + /// feature.* + #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct ParenthesizedGenericArguments { + pub paren_token: token::Paren, + /// `(A, B)` + pub inputs: Punctuated<Type, Token![,]>, + /// `C` + pub output: ReturnType, + } +} + +ast_struct! { + /// The explicit Self type in a qualified path: the `T` in `<T as + /// Display>::fmt`. + /// + /// The actual path, including the trait and the associated item, is stored + /// separately. The `position` field represents the index of the associated + /// item qualified with this Self type. + /// + /// ```text + /// <Vec<T> as a::b::Trait>::AssociatedItem + /// ^~~~~~ ~~~~~~~~~~~~~~^ + /// ty position = 3 + /// + /// <Vec<T>>::AssociatedItem + /// ^~~~~~ ^ + /// ty position = 0 + /// ``` + /// + /// *This type is available only if Syn is built with the `"derive"` or `"full"` + /// feature.* + #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))] + pub struct QSelf { + pub lt_token: Token![<], + pub ty: Box<Type>, + pub position: usize, + pub as_token: Option<Token![as]>, + pub gt_token: Token![>], + } +} + +#[cfg(feature = "parsing")] +pub mod parsing { + use super::*; + + use crate::ext::IdentExt; + use crate::parse::{Parse, ParseStream, Result}; + + #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] + impl Parse for Path { + fn parse(input: ParseStream) -> Result<Self> { + Self::parse_helper(input, false) + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] + impl Parse for GenericArgument { + fn parse(input: ParseStream) -> Result<Self> { + if input.peek(Lifetime) && !input.peek2(Token![+]) { + return Ok(GenericArgument::Lifetime(input.parse()?)); + } + + if input.peek(Ident) && input.peek2(Token![=]) { + let ident: Ident = input.parse()?; + let eq_token: Token![=] = input.parse()?; + + let ty = if input.peek(Lit) { + let begin = input.fork(); + input.parse::<Lit>()?; + Type::Verbatim(verbatim::between(begin, input)) + } else if input.peek(token::Brace) { + let begin = input.fork(); + + #[cfg(feature = "full")] + { + input.parse::<ExprBlock>()?; + } + + #[cfg(not(feature = "full"))] + { + let content; + braced!(content in input); + content.parse::<Expr>()?; + } + + Type::Verbatim(verbatim::between(begin, input)) + } else { + input.parse()? + }; + + return Ok(GenericArgument::Binding(Binding { + ident, + eq_token, + ty, + })); + } + + #[cfg(feature = "full")] + { + if input.peek(Ident) && input.peek2(Token![:]) && !input.peek2(Token![::]) { + return Ok(GenericArgument::Constraint(input.parse()?)); + } + } + + if input.peek(Lit) || input.peek(token::Brace) { + return const_argument(input).map(GenericArgument::Const); + } + + #[cfg(feature = "full")] + let begin = input.fork(); + + let argument: Type = input.parse()?; + + #[cfg(feature = "full")] + { + if match &argument { + Type::Path(argument) + if argument.qself.is_none() + && argument.path.leading_colon.is_none() + && argument.path.segments.len() == 1 => + { + match argument.path.segments[0].arguments { + PathArguments::AngleBracketed(_) => true, + _ => false, + } + } + _ => false, + } && if input.peek(Token![=]) { + input.parse::<Token![=]>()?; + input.parse::<Type>()?; + true + } else if input.peek(Token![:]) { + input.parse::<Token![:]>()?; + input.call(constraint_bounds)?; + true + } else { + false + } { + let verbatim = verbatim::between(begin, input); + return Ok(GenericArgument::Type(Type::Verbatim(verbatim))); + } + } + + Ok(GenericArgument::Type(argument)) + } + } + + pub fn const_argument(input: ParseStream) -> Result<Expr> { + let lookahead = input.lookahead1(); + + if input.peek(Lit) { + let lit = input.parse()?; + return Ok(Expr::Lit(lit)); + } + + #[cfg(feature = "full")] + { + if input.peek(Ident) { + let ident: Ident = input.parse()?; + return Ok(Expr::Path(ExprPath { + attrs: Vec::new(), + qself: None, + path: Path::from(ident), + })); + } + } + + if input.peek(token::Brace) { + #[cfg(feature = "full")] + { + let block: ExprBlock = input.parse()?; + return Ok(Expr::Block(block)); + } + + #[cfg(not(feature = "full"))] + { + let begin = input.fork(); + let content; + braced!(content in input); + content.parse::<Expr>()?; + let verbatim = verbatim::between(begin, input); + return Ok(Expr::Verbatim(verbatim)); + } + } + + Err(lookahead.error()) + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] + impl Parse for AngleBracketedGenericArguments { + fn parse(input: ParseStream) -> Result<Self> { + Ok(AngleBracketedGenericArguments { + colon2_token: input.parse()?, + lt_token: input.parse()?, + args: { + let mut args = Punctuated::new(); + loop { + if input.peek(Token![>]) { + break; + } + let value = input.parse()?; + args.push_value(value); + if input.peek(Token![>]) { + break; + } + let punct = input.parse()?; + args.push_punct(punct); + } + args + }, + gt_token: input.parse()?, + }) + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] + impl Parse for ParenthesizedGenericArguments { + fn parse(input: ParseStream) -> Result<Self> { + let content; + Ok(ParenthesizedGenericArguments { + paren_token: parenthesized!(content in input), + inputs: content.parse_terminated(Type::parse)?, + output: input.call(ReturnType::without_plus)?, + }) + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] + impl Parse for PathSegment { + fn parse(input: ParseStream) -> Result<Self> { + Self::parse_helper(input, false) + } + } + + impl PathSegment { + fn parse_helper(input: ParseStream, expr_style: bool) -> Result<Self> { + if input.peek(Token![super]) || input.peek(Token![self]) || input.peek(Token![crate]) { + let ident = input.call(Ident::parse_any)?; + return Ok(PathSegment::from(ident)); + } + + let ident = if input.peek(Token![Self]) { + input.call(Ident::parse_any)? + } else { + input.parse()? + }; + + if !expr_style && input.peek(Token![<]) && !input.peek(Token![<=]) + || input.peek(Token![::]) && input.peek3(Token![<]) + { + Ok(PathSegment { + ident, + arguments: PathArguments::AngleBracketed(input.parse()?), + }) + } else { + Ok(PathSegment::from(ident)) + } + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] + impl Parse for Binding { + fn parse(input: ParseStream) -> Result<Self> { + Ok(Binding { + ident: input.parse()?, + eq_token: input.parse()?, + ty: input.parse()?, + }) + } + } + + #[cfg(feature = "full")] + #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] + impl Parse for Constraint { + fn parse(input: ParseStream) -> Result<Self> { + Ok(Constraint { + ident: input.parse()?, + colon_token: input.parse()?, + bounds: constraint_bounds(input)?, + }) + } + } + + #[cfg(feature = "full")] + fn constraint_bounds(input: ParseStream) -> Result<Punctuated<TypeParamBound, Token![+]>> { + let mut bounds = Punctuated::new(); + loop { + if input.peek(Token![,]) || input.peek(Token![>]) { + break; + } + let value = input.parse()?; + bounds.push_value(value); + if !input.peek(Token![+]) { + break; + } + let punct = input.parse()?; + bounds.push_punct(punct); + } + Ok(bounds) + } + + impl Path { + /// Parse a `Path` containing no path arguments on any of its segments. + /// + /// *This function is available only if Syn is built with the `"parsing"` + /// feature.* + /// + /// # Example + /// + /// ``` + /// use syn::{Path, Result, Token}; + /// use syn::parse::{Parse, ParseStream}; + /// + /// // A simplified single `use` statement like: + /// // + /// // use std::collections::HashMap; + /// // + /// // Note that generic parameters are not allowed in a `use` statement + /// // so the following must not be accepted. + /// // + /// // use a::<b>::c; + /// struct SingleUse { + /// use_token: Token![use], + /// path: Path, + /// } + /// + /// impl Parse for SingleUse { + /// fn parse(input: ParseStream) -> Result<Self> { + /// Ok(SingleUse { + /// use_token: input.parse()?, + /// path: input.call(Path::parse_mod_style)?, + /// }) + /// } + /// } + /// ``` + #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] + pub fn parse_mod_style(input: ParseStream) -> Result<Self> { + Ok(Path { + leading_colon: input.parse()?, + segments: { + let mut segments = Punctuated::new(); + loop { + if !input.peek(Ident) + && !input.peek(Token![super]) + && !input.peek(Token![self]) + && !input.peek(Token![Self]) + && !input.peek(Token![crate]) + { + break; + } + 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 + }, + }) + } + + /// Determines whether this is a path of length 1 equal to the given + /// ident. + /// + /// For them to compare equal, it must be the case that: + /// + /// - the path has no leading colon, + /// - the number of path segments is 1, + /// - the first path segment has no angle bracketed or parenthesized + /// path arguments, and + /// - the ident of the first path segment is equal to the given one. + /// + /// *This function is available only if Syn is built with the `"parsing"` + /// feature.* + /// + /// # Example + /// + /// ``` + /// use syn::{Attribute, Error, Meta, NestedMeta, Result}; + /// # use std::iter::FromIterator; + /// + /// fn get_serde_meta_items(attr: &Attribute) -> Result<Vec<NestedMeta>> { + /// if attr.path.is_ident("serde") { + /// match attr.parse_meta()? { + /// Meta::List(meta) => Ok(Vec::from_iter(meta.nested)), + /// bad => Err(Error::new_spanned(bad, "unrecognized attribute")), + /// } + /// } else { + /// Ok(Vec::new()) + /// } + /// } + /// ``` + #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] + pub fn is_ident<I: ?Sized>(&self, ident: &I) -> bool + where + Ident: PartialEq<I>, + { + match self.get_ident() { + Some(id) => id == ident, + None => false, + } + } + + /// If this path consists of a single ident, returns the ident. + /// + /// A path is considered an ident if: + /// + /// - the path has no leading colon, + /// - the number of path segments is 1, and + /// - the first path segment has no angle bracketed or parenthesized + /// path arguments. + /// + /// *This function is available only if Syn is built with the `"parsing"` + /// feature.* + #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))] + pub fn get_ident(&self) -> Option<&Ident> { + if self.leading_colon.is_none() + && self.segments.len() == 1 + && self.segments[0].arguments.is_none() + { + Some(&self.segments[0].ident) + } else { + None + } + } + + pub(crate) fn parse_helper(input: ParseStream, expr_style: bool) -> Result<Self> { + let mut path = Path { + leading_colon: input.parse()?, + segments: { + let mut segments = Punctuated::new(); + let value = PathSegment::parse_helper(input, expr_style)?; + segments.push_value(value); + segments + }, + }; + Path::parse_rest(input, &mut path, expr_style)?; + Ok(path) + } + + pub(crate) fn parse_rest( + input: ParseStream, + path: &mut Self, + expr_style: bool, + ) -> Result<()> { + while input.peek(Token![::]) && !input.peek3(token::Paren) { + let punct: Token![::] = input.parse()?; + path.segments.push_punct(punct); + let value = PathSegment::parse_helper(input, expr_style)?; + path.segments.push_value(value); + } + Ok(()) + } + } + + pub fn qpath(input: ParseStream, expr_style: bool) -> Result<(Option<QSelf>, Path)> { + if input.peek(Token![<]) { + let lt_token: Token![<] = input.parse()?; + let this: Type = input.parse()?; + let path = if input.peek(Token![as]) { + let as_token: Token![as] = input.parse()?; + let path: Path = input.parse()?; + Some((as_token, path)) + } else { + None + }; + let gt_token: Token![>] = input.parse()?; + let colon2_token: Token![::] = input.parse()?; + let mut rest = Punctuated::new(); + loop { + let path = PathSegment::parse_helper(input, expr_style)?; + rest.push_value(path); + if !input.peek(Token![::]) { + break; + } + let punct: Token![::] = input.parse()?; + rest.push_punct(punct); + } + let (position, as_token, path) = match path { + Some((as_token, mut path)) => { + let pos = path.segments.len(); + path.segments.push_punct(colon2_token); + path.segments.extend(rest.into_pairs()); + (pos, Some(as_token), path) + } + None => { + let path = Path { + leading_colon: Some(colon2_token), + segments: rest, + }; + (0, None, path) + } + }; + let qself = QSelf { + lt_token, + ty: Box::new(this), + position, + as_token, + gt_token, + }; + Ok((Some(qself), path)) + } else { + let path = Path::parse_helper(input, expr_style)?; + Ok((None, path)) + } + } +} + +#[cfg(feature = "printing")] +pub(crate) mod printing { + use super::*; + use crate::print::TokensOrDefault; + use proc_macro2::TokenStream; + use quote::ToTokens; + use std::cmp; + + #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))] + impl ToTokens for Path { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.leading_colon.to_tokens(tokens); + self.segments.to_tokens(tokens); + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))] + impl ToTokens for PathSegment { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.ident.to_tokens(tokens); + self.arguments.to_tokens(tokens); + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))] + impl ToTokens for PathArguments { + fn to_tokens(&self, tokens: &mut TokenStream) { + match self { + PathArguments::None => {} + PathArguments::AngleBracketed(arguments) => { + arguments.to_tokens(tokens); + } + PathArguments::Parenthesized(arguments) => { + arguments.to_tokens(tokens); + } + } + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))] + impl ToTokens for GenericArgument { + #[allow(clippy::match_same_arms)] + fn to_tokens(&self, tokens: &mut TokenStream) { + match self { + GenericArgument::Lifetime(lt) => lt.to_tokens(tokens), + GenericArgument::Type(ty) => ty.to_tokens(tokens), + GenericArgument::Const(e) => match *e { + Expr::Lit(_) => e.to_tokens(tokens), + + // NOTE: We should probably support parsing blocks with only + // expressions in them without the full feature for const + // generics. + #[cfg(feature = "full")] + Expr::Block(_) => e.to_tokens(tokens), + + // ERROR CORRECTION: Add braces to make sure that the + // generated code is valid. + _ => token::Brace::default().surround(tokens, |tokens| { + e.to_tokens(tokens); + }), + }, + GenericArgument::Binding(tb) => tb.to_tokens(tokens), + GenericArgument::Constraint(tc) => tc.to_tokens(tokens), + } + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))] + impl ToTokens for AngleBracketedGenericArguments { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.colon2_token.to_tokens(tokens); + self.lt_token.to_tokens(tokens); + + // Print lifetimes before types/consts/bindings, regardless of their + // order in self.args. + let mut trailing_or_empty = true; + for param in self.args.pairs() { + match **param.value() { + GenericArgument::Lifetime(_) => { + param.to_tokens(tokens); + trailing_or_empty = param.punct().is_some(); + } + GenericArgument::Type(_) + | GenericArgument::Const(_) + | GenericArgument::Binding(_) + | GenericArgument::Constraint(_) => {} + } + } + for param in self.args.pairs() { + match **param.value() { + GenericArgument::Type(_) + | GenericArgument::Const(_) + | GenericArgument::Binding(_) + | GenericArgument::Constraint(_) => { + if !trailing_or_empty { + <Token![,]>::default().to_tokens(tokens); + } + param.to_tokens(tokens); + trailing_or_empty = param.punct().is_some(); + } + GenericArgument::Lifetime(_) => {} + } + } + + self.gt_token.to_tokens(tokens); + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))] + impl ToTokens for Binding { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.ident.to_tokens(tokens); + self.eq_token.to_tokens(tokens); + self.ty.to_tokens(tokens); + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))] + impl ToTokens for Constraint { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.ident.to_tokens(tokens); + self.colon_token.to_tokens(tokens); + self.bounds.to_tokens(tokens); + } + } + + #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))] + impl ToTokens for ParenthesizedGenericArguments { + fn to_tokens(&self, tokens: &mut TokenStream) { + self.paren_token.surround(tokens, |tokens| { + self.inputs.to_tokens(tokens); + }); + self.output.to_tokens(tokens); + } + } + + pub(crate) fn print_path(tokens: &mut TokenStream, qself: &Option<QSelf>, path: &Path) { + let qself = match qself { + Some(qself) => qself, + None => { + path.to_tokens(tokens); + return; + } + }; + qself.lt_token.to_tokens(tokens); + qself.ty.to_tokens(tokens); + + let pos = cmp::min(qself.position, path.segments.len()); + let mut segments = path.segments.pairs(); + if pos > 0 { + TokensOrDefault(&qself.as_token).to_tokens(tokens); + path.leading_colon.to_tokens(tokens); + for (i, segment) in segments.by_ref().take(pos).enumerate() { + if i + 1 == pos { + segment.value().to_tokens(tokens); + qself.gt_token.to_tokens(tokens); + segment.punct().to_tokens(tokens); + } else { + segment.to_tokens(tokens); + } + } + } else { + qself.gt_token.to_tokens(tokens); + path.leading_colon.to_tokens(tokens); + } + for segment in segments { + segment.to_tokens(tokens); + } + } +} |