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-rw-r--r--vendor/syn/src/pat.rs917
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diff --git a/vendor/syn/src/pat.rs b/vendor/syn/src/pat.rs
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+use super::*;
+use crate::punctuated::Punctuated;
+use proc_macro2::TokenStream;
+
+ast_enum_of_structs! {
+ /// A pattern in a local binding, function signature, match expression, or
+ /// various other places.
+ ///
+ /// # Syntax tree enum
+ ///
+ /// This type is a [syntax tree enum].
+ ///
+ /// [syntax tree enum]: Expr#syntax-tree-enums
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+ #[non_exhaustive]
+ pub enum Pat {
+ /// A const block: `const { ... }`.
+ Const(PatConst),
+
+ /// A pattern that binds a new variable: `ref mut binding @ SUBPATTERN`.
+ Ident(PatIdent),
+
+ /// A literal pattern: `0`.
+ Lit(PatLit),
+
+ /// A macro in pattern position.
+ Macro(PatMacro),
+
+ /// A pattern that matches any one of a set of cases.
+ Or(PatOr),
+
+ /// A parenthesized pattern: `(A | B)`.
+ Paren(PatParen),
+
+ /// A path pattern like `Color::Red`, optionally qualified with a
+ /// self-type.
+ ///
+ /// Unqualified path patterns can legally refer to variants, structs,
+ /// constants or associated constants. Qualified path patterns like
+ /// `<A>::B::C` and `<A as Trait>::B::C` can only legally refer to
+ /// associated constants.
+ Path(PatPath),
+
+ /// A range pattern: `1..=2`.
+ Range(PatRange),
+
+ /// A reference pattern: `&mut var`.
+ Reference(PatReference),
+
+ /// The dots in a tuple or slice pattern: `[0, 1, ..]`.
+ Rest(PatRest),
+
+ /// A dynamically sized slice pattern: `[a, b, ref i @ .., y, z]`.
+ Slice(PatSlice),
+
+ /// A struct or struct variant pattern: `Variant { x, y, .. }`.
+ Struct(PatStruct),
+
+ /// A tuple pattern: `(a, b)`.
+ Tuple(PatTuple),
+
+ /// A tuple struct or tuple variant pattern: `Variant(x, y, .., z)`.
+ TupleStruct(PatTupleStruct),
+
+ /// A type ascription pattern: `foo: f64`.
+ Type(PatType),
+
+ /// Tokens in pattern position not interpreted by Syn.
+ Verbatim(TokenStream),
+
+ /// A pattern that matches any value: `_`.
+ Wild(PatWild),
+
+ // For testing exhaustiveness in downstream code, use the following idiom:
+ //
+ // match pat {
+ // #![cfg_attr(test, deny(non_exhaustive_omitted_patterns))]
+ //
+ // Pat::Box(pat) => {...}
+ // Pat::Ident(pat) => {...}
+ // ...
+ // Pat::Wild(pat) => {...}
+ //
+ // _ => { /* some sane fallback */ }
+ // }
+ //
+ // This way we fail your tests but don't break your library when adding
+ // a variant. You will be notified by a test failure when a variant is
+ // added, so that you can add code to handle it, but your library will
+ // continue to compile and work for downstream users in the interim.
+ }
+}
+
+ast_struct! {
+ /// A pattern that binds a new variable: `ref mut binding @ SUBPATTERN`.
+ ///
+ /// It may also be a unit struct or struct variant (e.g. `None`), or a
+ /// constant; these cannot be distinguished syntactically.
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+ pub struct PatIdent {
+ pub attrs: Vec<Attribute>,
+ pub by_ref: Option<Token![ref]>,
+ pub mutability: Option<Token![mut]>,
+ pub ident: Ident,
+ pub subpat: Option<(Token![@], Box<Pat>)>,
+ }
+}
+
+ast_struct! {
+ /// A pattern that matches any one of a set of cases.
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+ pub struct PatOr {
+ pub attrs: Vec<Attribute>,
+ pub leading_vert: Option<Token![|]>,
+ pub cases: Punctuated<Pat, Token![|]>,
+ }
+}
+
+ast_struct! {
+ /// A parenthesized pattern: `(A | B)`.
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+ pub struct PatParen {
+ pub attrs: Vec<Attribute>,
+ pub paren_token: token::Paren,
+ pub pat: Box<Pat>,
+ }
+}
+
+ast_struct! {
+ /// A reference pattern: `&mut var`.
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+ pub struct PatReference {
+ pub attrs: Vec<Attribute>,
+ pub and_token: Token![&],
+ pub mutability: Option<Token![mut]>,
+ pub pat: Box<Pat>,
+ }
+}
+
+ast_struct! {
+ /// The dots in a tuple or slice pattern: `[0, 1, ..]`.
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+ pub struct PatRest {
+ pub attrs: Vec<Attribute>,
+ pub dot2_token: Token![..],
+ }
+}
+
+ast_struct! {
+ /// A dynamically sized slice pattern: `[a, b, ref i @ .., y, z]`.
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+ pub struct PatSlice {
+ pub attrs: Vec<Attribute>,
+ pub bracket_token: token::Bracket,
+ pub elems: Punctuated<Pat, Token![,]>,
+ }
+}
+
+ast_struct! {
+ /// A struct or struct variant pattern: `Variant { x, y, .. }`.
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+ pub struct PatStruct {
+ pub attrs: Vec<Attribute>,
+ pub qself: Option<QSelf>,
+ pub path: Path,
+ pub brace_token: token::Brace,
+ pub fields: Punctuated<FieldPat, Token![,]>,
+ pub rest: Option<PatRest>,
+ }
+}
+
+ast_struct! {
+ /// A tuple pattern: `(a, b)`.
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+ pub struct PatTuple {
+ pub attrs: Vec<Attribute>,
+ pub paren_token: token::Paren,
+ pub elems: Punctuated<Pat, Token![,]>,
+ }
+}
+
+ast_struct! {
+ /// A tuple struct or tuple variant pattern: `Variant(x, y, .., z)`.
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+ pub struct PatTupleStruct {
+ pub attrs: Vec<Attribute>,
+ pub qself: Option<QSelf>,
+ pub path: Path,
+ pub paren_token: token::Paren,
+ pub elems: Punctuated<Pat, Token![,]>,
+ }
+}
+
+ast_struct! {
+ /// A type ascription pattern: `foo: f64`.
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+ pub struct PatType {
+ pub attrs: Vec<Attribute>,
+ pub pat: Box<Pat>,
+ pub colon_token: Token![:],
+ pub ty: Box<Type>,
+ }
+}
+
+ast_struct! {
+ /// A pattern that matches any value: `_`.
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+ pub struct PatWild {
+ pub attrs: Vec<Attribute>,
+ pub underscore_token: Token![_],
+ }
+}
+
+ast_struct! {
+ /// A single field in a struct pattern.
+ ///
+ /// Patterns like the fields of Foo `{ x, ref y, ref mut z }` are treated
+ /// the same as `x: x, y: ref y, z: ref mut z` but there is no colon token.
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+ pub struct FieldPat {
+ pub attrs: Vec<Attribute>,
+ pub member: Member,
+ pub colon_token: Option<Token![:]>,
+ pub pat: Box<Pat>,
+ }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+ use super::*;
+ use crate::ext::IdentExt as _;
+ use crate::parse::{Parse, ParseBuffer, ParseStream, Result};
+ use crate::path;
+
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+ impl Pat {
+ /// Parse a pattern that does _not_ involve `|` at the top level.
+ ///
+ /// This parser matches the behavior of the `$:pat_param` macro_rules
+ /// matcher, and on editions prior to Rust 2021, the behavior of
+ /// `$:pat`.
+ ///
+ /// In Rust syntax, some examples of where this syntax would occur are
+ /// in the argument pattern of functions and closures. Patterns using
+ /// `|` are not allowed to occur in these positions.
+ ///
+ /// ```compile_fail
+ /// fn f(Some(_) | None: Option<T>) {
+ /// let _ = |Some(_) | None: Option<T>| {};
+ /// // ^^^^^^^^^^^^^^^^^^^^^^^^^??? :(
+ /// }
+ /// ```
+ ///
+ /// ```console
+ /// error: top-level or-patterns are not allowed in function parameters
+ /// --> src/main.rs:1:6
+ /// |
+ /// 1 | fn f(Some(_) | None: Option<T>) {
+ /// | ^^^^^^^^^^^^^^ help: wrap the pattern in parentheses: `(Some(_) | None)`
+ /// ```
+ pub fn parse_single(input: ParseStream) -> Result<Self> {
+ let begin = input.fork();
+ let lookahead = input.lookahead1();
+ if lookahead.peek(Ident)
+ && (input.peek2(Token![::])
+ || input.peek2(Token![!])
+ || input.peek2(token::Brace)
+ || input.peek2(token::Paren)
+ || input.peek2(Token![..]))
+ || input.peek(Token![self]) && input.peek2(Token![::])
+ || lookahead.peek(Token![::])
+ || lookahead.peek(Token![<])
+ || input.peek(Token![Self])
+ || input.peek(Token![super])
+ || input.peek(Token![crate])
+ {
+ pat_path_or_macro_or_struct_or_range(input)
+ } else if lookahead.peek(Token![_]) {
+ input.call(pat_wild).map(Pat::Wild)
+ } else if input.peek(Token![box]) {
+ pat_box(begin, input)
+ } else if input.peek(Token![-]) || lookahead.peek(Lit) || lookahead.peek(Token![const])
+ {
+ pat_lit_or_range(input)
+ } else if lookahead.peek(Token![ref])
+ || lookahead.peek(Token![mut])
+ || input.peek(Token![self])
+ || input.peek(Ident)
+ {
+ input.call(pat_ident).map(Pat::Ident)
+ } else if lookahead.peek(Token![&]) {
+ input.call(pat_reference).map(Pat::Reference)
+ } else if lookahead.peek(token::Paren) {
+ input.call(pat_paren_or_tuple)
+ } else if lookahead.peek(token::Bracket) {
+ input.call(pat_slice).map(Pat::Slice)
+ } else if lookahead.peek(Token![..]) && !input.peek(Token![...]) {
+ pat_range_half_open(input)
+ } else if lookahead.peek(Token![const]) {
+ input.call(pat_const).map(Pat::Verbatim)
+ } else {
+ Err(lookahead.error())
+ }
+ }
+
+ /// Parse a pattern, possibly involving `|`, but not a leading `|`.
+ pub fn parse_multi(input: ParseStream) -> Result<Self> {
+ multi_pat_impl(input, None)
+ }
+
+ /// Parse a pattern, possibly involving `|`, possibly including a
+ /// leading `|`.
+ ///
+ /// This parser matches the behavior of the Rust 2021 edition's `$:pat`
+ /// macro_rules matcher.
+ ///
+ /// In Rust syntax, an example of where this syntax would occur is in
+ /// the pattern of a `match` arm, where the language permits an optional
+ /// leading `|`, although it is not idiomatic to write one there in
+ /// handwritten code.
+ ///
+ /// ```
+ /// # let wat = None;
+ /// match wat {
+ /// | None | Some(false) => {}
+ /// | Some(true) => {}
+ /// }
+ /// ```
+ ///
+ /// The compiler accepts it only to facilitate some situations in
+ /// macro-generated code where a macro author might need to write:
+ ///
+ /// ```
+ /// # macro_rules! doc {
+ /// # ($value:expr, ($($conditions1:pat),*), ($($conditions2:pat),*), $then:expr) => {
+ /// match $value {
+ /// $(| $conditions1)* $(| $conditions2)* => $then
+ /// }
+ /// # };
+ /// # }
+ /// #
+ /// # doc!(true, (true), (false), {});
+ /// # doc!(true, (), (true, false), {});
+ /// # doc!(true, (true, false), (), {});
+ /// ```
+ ///
+ /// Expressing the same thing correctly in the case that either one (but
+ /// not both) of `$conditions1` and `$conditions2` might be empty,
+ /// without leading `|`, is complex.
+ ///
+ /// Use [`Pat::parse_multi`] instead if you are not intending to support
+ /// macro-generated macro input.
+ pub fn parse_multi_with_leading_vert(input: ParseStream) -> Result<Self> {
+ let leading_vert: Option<Token![|]> = input.parse()?;
+ multi_pat_impl(input, leading_vert)
+ }
+ }
+
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+ impl Parse for PatType {
+ fn parse(input: ParseStream) -> Result<Self> {
+ Ok(PatType {
+ attrs: Vec::new(),
+ pat: Box::new(Pat::parse_single(input)?),
+ colon_token: input.parse()?,
+ ty: input.parse()?,
+ })
+ }
+ }
+
+ fn multi_pat_impl(input: ParseStream, leading_vert: Option<Token![|]>) -> Result<Pat> {
+ let mut pat = Pat::parse_single(input)?;
+ if leading_vert.is_some()
+ || input.peek(Token![|]) && !input.peek(Token![||]) && !input.peek(Token![|=])
+ {
+ let mut cases = Punctuated::new();
+ cases.push_value(pat);
+ while input.peek(Token![|]) && !input.peek(Token![||]) && !input.peek(Token![|=]) {
+ let punct = input.parse()?;
+ cases.push_punct(punct);
+ let pat = Pat::parse_single(input)?;
+ cases.push_value(pat);
+ }
+ pat = Pat::Or(PatOr {
+ attrs: Vec::new(),
+ leading_vert,
+ cases,
+ });
+ }
+ Ok(pat)
+ }
+
+ fn pat_path_or_macro_or_struct_or_range(input: ParseStream) -> Result<Pat> {
+ let (qself, path) = path::parsing::qpath(input, true)?;
+
+ if qself.is_none()
+ && input.peek(Token![!])
+ && !input.peek(Token![!=])
+ && path.is_mod_style()
+ {
+ let bang_token: Token![!] = input.parse()?;
+ let (delimiter, tokens) = mac::parse_delimiter(input)?;
+ return Ok(Pat::Macro(ExprMacro {
+ attrs: Vec::new(),
+ mac: Macro {
+ path,
+ bang_token,
+ delimiter,
+ tokens,
+ },
+ }));
+ }
+
+ if input.peek(token::Brace) {
+ pat_struct(input, qself, path).map(Pat::Struct)
+ } else if input.peek(token::Paren) {
+ pat_tuple_struct(input, qself, path).map(Pat::TupleStruct)
+ } else if input.peek(Token![..]) {
+ pat_range(input, qself, path)
+ } else {
+ Ok(Pat::Path(ExprPath {
+ attrs: Vec::new(),
+ qself,
+ path,
+ }))
+ }
+ }
+
+ fn pat_wild(input: ParseStream) -> Result<PatWild> {
+ Ok(PatWild {
+ attrs: Vec::new(),
+ underscore_token: input.parse()?,
+ })
+ }
+
+ fn pat_box(begin: ParseBuffer, input: ParseStream) -> Result<Pat> {
+ input.parse::<Token![box]>()?;
+ Pat::parse_single(input)?;
+ Ok(Pat::Verbatim(verbatim::between(&begin, input)))
+ }
+
+ fn pat_ident(input: ParseStream) -> Result<PatIdent> {
+ Ok(PatIdent {
+ attrs: Vec::new(),
+ by_ref: input.parse()?,
+ mutability: input.parse()?,
+ ident: input.call(Ident::parse_any)?,
+ subpat: {
+ if input.peek(Token![@]) {
+ let at_token: Token![@] = input.parse()?;
+ let subpat = Pat::parse_single(input)?;
+ Some((at_token, Box::new(subpat)))
+ } else {
+ None
+ }
+ },
+ })
+ }
+
+ fn pat_tuple_struct(
+ input: ParseStream,
+ qself: Option<QSelf>,
+ path: Path,
+ ) -> Result<PatTupleStruct> {
+ let content;
+ let paren_token = parenthesized!(content in input);
+
+ let mut elems = Punctuated::new();
+ while !content.is_empty() {
+ let value = Pat::parse_multi_with_leading_vert(&content)?;
+ elems.push_value(value);
+ if content.is_empty() {
+ break;
+ }
+ let punct = content.parse()?;
+ elems.push_punct(punct);
+ }
+
+ Ok(PatTupleStruct {
+ attrs: Vec::new(),
+ qself,
+ path,
+ paren_token,
+ elems,
+ })
+ }
+
+ fn pat_struct(input: ParseStream, qself: Option<QSelf>, path: Path) -> Result<PatStruct> {
+ let content;
+ let brace_token = braced!(content in input);
+
+ let mut fields = Punctuated::new();
+ let mut rest = None;
+ while !content.is_empty() {
+ let attrs = content.call(Attribute::parse_outer)?;
+ if content.peek(Token![..]) {
+ rest = Some(PatRest {
+ attrs,
+ dot2_token: content.parse()?,
+ });
+ break;
+ }
+ let mut value = content.call(field_pat)?;
+ value.attrs = attrs;
+ fields.push_value(value);
+ if content.is_empty() {
+ break;
+ }
+ let punct: Token![,] = content.parse()?;
+ fields.push_punct(punct);
+ }
+
+ Ok(PatStruct {
+ attrs: Vec::new(),
+ qself,
+ path,
+ brace_token,
+ fields,
+ rest,
+ })
+ }
+
+ fn field_pat(input: ParseStream) -> Result<FieldPat> {
+ let begin = input.fork();
+ let boxed: Option<Token![box]> = input.parse()?;
+ let by_ref: Option<Token![ref]> = input.parse()?;
+ let mutability: Option<Token![mut]> = input.parse()?;
+
+ let member = if boxed.is_some() || by_ref.is_some() || mutability.is_some() {
+ input.parse().map(Member::Named)
+ } else {
+ input.parse()
+ }?;
+
+ if boxed.is_none() && by_ref.is_none() && mutability.is_none() && input.peek(Token![:])
+ || !member.is_named()
+ {
+ return Ok(FieldPat {
+ attrs: Vec::new(),
+ member,
+ colon_token: Some(input.parse()?),
+ pat: Box::new(Pat::parse_multi_with_leading_vert(input)?),
+ });
+ }
+
+ let ident = match member {
+ Member::Named(ident) => ident,
+ Member::Unnamed(_) => unreachable!(),
+ };
+
+ let pat = if boxed.is_some() {
+ Pat::Verbatim(verbatim::between(&begin, input))
+ } else {
+ Pat::Ident(PatIdent {
+ attrs: Vec::new(),
+ by_ref,
+ mutability,
+ ident: ident.clone(),
+ subpat: None,
+ })
+ };
+
+ Ok(FieldPat {
+ attrs: Vec::new(),
+ member: Member::Named(ident),
+ colon_token: None,
+ pat: Box::new(pat),
+ })
+ }
+
+ fn pat_range(input: ParseStream, qself: Option<QSelf>, path: Path) -> Result<Pat> {
+ let limits = RangeLimits::parse_obsolete(input)?;
+ let end = input.call(pat_range_bound)?;
+ if let (RangeLimits::Closed(_), None) = (&limits, &end) {
+ return Err(input.error("expected range upper bound"));
+ }
+ Ok(Pat::Range(ExprRange {
+ attrs: Vec::new(),
+ start: Some(Box::new(Expr::Path(ExprPath {
+ attrs: Vec::new(),
+ qself,
+ path,
+ }))),
+ limits,
+ end: end.map(PatRangeBound::into_expr),
+ }))
+ }
+
+ fn pat_range_half_open(input: ParseStream) -> Result<Pat> {
+ let limits: RangeLimits = input.parse()?;
+ let end = input.call(pat_range_bound)?;
+ if end.is_some() {
+ Ok(Pat::Range(ExprRange {
+ attrs: Vec::new(),
+ start: None,
+ limits,
+ end: end.map(PatRangeBound::into_expr),
+ }))
+ } else {
+ match limits {
+ RangeLimits::HalfOpen(dot2_token) => Ok(Pat::Rest(PatRest {
+ attrs: Vec::new(),
+ dot2_token,
+ })),
+ RangeLimits::Closed(_) => Err(input.error("expected range upper bound")),
+ }
+ }
+ }
+
+ fn pat_paren_or_tuple(input: ParseStream) -> Result<Pat> {
+ let content;
+ let paren_token = parenthesized!(content in input);
+
+ let mut elems = Punctuated::new();
+ while !content.is_empty() {
+ let value = Pat::parse_multi_with_leading_vert(&content)?;
+ if content.is_empty() {
+ if elems.is_empty() && !matches!(value, Pat::Rest(_)) {
+ return Ok(Pat::Paren(PatParen {
+ attrs: Vec::new(),
+ paren_token,
+ pat: Box::new(value),
+ }));
+ }
+ elems.push_value(value);
+ break;
+ }
+ elems.push_value(value);
+ let punct = content.parse()?;
+ elems.push_punct(punct);
+ }
+
+ Ok(Pat::Tuple(PatTuple {
+ attrs: Vec::new(),
+ paren_token,
+ elems,
+ }))
+ }
+
+ fn pat_reference(input: ParseStream) -> Result<PatReference> {
+ Ok(PatReference {
+ attrs: Vec::new(),
+ and_token: input.parse()?,
+ mutability: input.parse()?,
+ pat: Box::new(Pat::parse_single(input)?),
+ })
+ }
+
+ fn pat_lit_or_range(input: ParseStream) -> Result<Pat> {
+ let start = input.call(pat_range_bound)?.unwrap();
+ if input.peek(Token![..]) {
+ let limits = RangeLimits::parse_obsolete(input)?;
+ let end = input.call(pat_range_bound)?;
+ if let (RangeLimits::Closed(_), None) = (&limits, &end) {
+ return Err(input.error("expected range upper bound"));
+ }
+ Ok(Pat::Range(ExprRange {
+ attrs: Vec::new(),
+ start: Some(start.into_expr()),
+ limits,
+ end: end.map(PatRangeBound::into_expr),
+ }))
+ } else {
+ Ok(start.into_pat())
+ }
+ }
+
+ // Patterns that can appear on either side of a range pattern.
+ enum PatRangeBound {
+ Const(ExprConst),
+ Lit(ExprLit),
+ Path(ExprPath),
+ }
+
+ impl PatRangeBound {
+ fn into_expr(self) -> Box<Expr> {
+ Box::new(match self {
+ PatRangeBound::Const(pat) => Expr::Const(pat),
+ PatRangeBound::Lit(pat) => Expr::Lit(pat),
+ PatRangeBound::Path(pat) => Expr::Path(pat),
+ })
+ }
+
+ fn into_pat(self) -> Pat {
+ match self {
+ PatRangeBound::Const(pat) => Pat::Const(pat),
+ PatRangeBound::Lit(pat) => Pat::Lit(pat),
+ PatRangeBound::Path(pat) => Pat::Path(pat),
+ }
+ }
+ }
+
+ fn pat_range_bound(input: ParseStream) -> Result<Option<PatRangeBound>> {
+ if input.is_empty()
+ || input.peek(Token![|])
+ || input.peek(Token![=])
+ || input.peek(Token![:]) && !input.peek(Token![::])
+ || input.peek(Token![,])
+ || input.peek(Token![;])
+ || input.peek(Token![if])
+ {
+ return Ok(None);
+ }
+
+ let lookahead = input.lookahead1();
+ let expr = if lookahead.peek(Lit) {
+ PatRangeBound::Lit(input.parse()?)
+ } else if lookahead.peek(Ident)
+ || lookahead.peek(Token![::])
+ || lookahead.peek(Token![<])
+ || lookahead.peek(Token![self])
+ || lookahead.peek(Token![Self])
+ || lookahead.peek(Token![super])
+ || lookahead.peek(Token![crate])
+ {
+ PatRangeBound::Path(input.parse()?)
+ } else if lookahead.peek(Token![const]) {
+ PatRangeBound::Const(input.parse()?)
+ } else {
+ return Err(lookahead.error());
+ };
+
+ Ok(Some(expr))
+ }
+
+ fn pat_slice(input: ParseStream) -> Result<PatSlice> {
+ let content;
+ let bracket_token = bracketed!(content in input);
+
+ let mut elems = Punctuated::new();
+ while !content.is_empty() {
+ let value = Pat::parse_multi_with_leading_vert(&content)?;
+ match value {
+ Pat::Range(pat) if pat.start.is_none() || pat.end.is_none() => {
+ let (start, end) = match pat.limits {
+ RangeLimits::HalfOpen(dot_dot) => (dot_dot.spans[0], dot_dot.spans[1]),
+ RangeLimits::Closed(dot_dot_eq) => {
+ (dot_dot_eq.spans[0], dot_dot_eq.spans[2])
+ }
+ };
+ let msg = "range pattern is not allowed unparenthesized inside slice pattern";
+ return Err(error::new2(start, end, msg));
+ }
+ _ => {}
+ }
+ elems.push_value(value);
+ if content.is_empty() {
+ break;
+ }
+ let punct = content.parse()?;
+ elems.push_punct(punct);
+ }
+
+ Ok(PatSlice {
+ attrs: Vec::new(),
+ bracket_token,
+ elems,
+ })
+ }
+
+ fn pat_const(input: ParseStream) -> Result<TokenStream> {
+ let begin = input.fork();
+ input.parse::<Token![const]>()?;
+
+ let content;
+ braced!(content in input);
+ content.call(Attribute::parse_inner)?;
+ content.call(Block::parse_within)?;
+
+ Ok(verbatim::between(&begin, input))
+ }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+ use super::*;
+ use crate::attr::FilterAttrs;
+ use proc_macro2::TokenStream;
+ use quote::{ToTokens, TokenStreamExt};
+
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+ impl ToTokens for PatIdent {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ tokens.append_all(self.attrs.outer());
+ self.by_ref.to_tokens(tokens);
+ self.mutability.to_tokens(tokens);
+ self.ident.to_tokens(tokens);
+ if let Some((at_token, subpat)) = &self.subpat {
+ at_token.to_tokens(tokens);
+ subpat.to_tokens(tokens);
+ }
+ }
+ }
+
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+ impl ToTokens for PatOr {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ tokens.append_all(self.attrs.outer());
+ self.leading_vert.to_tokens(tokens);
+ self.cases.to_tokens(tokens);
+ }
+ }
+
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+ impl ToTokens for PatParen {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ tokens.append_all(self.attrs.outer());
+ self.paren_token.surround(tokens, |tokens| {
+ self.pat.to_tokens(tokens);
+ });
+ }
+ }
+
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+ impl ToTokens for PatReference {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ tokens.append_all(self.attrs.outer());
+ self.and_token.to_tokens(tokens);
+ self.mutability.to_tokens(tokens);
+ self.pat.to_tokens(tokens);
+ }
+ }
+
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+ impl ToTokens for PatRest {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ tokens.append_all(self.attrs.outer());
+ self.dot2_token.to_tokens(tokens);
+ }
+ }
+
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+ impl ToTokens for PatSlice {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ tokens.append_all(self.attrs.outer());
+ self.bracket_token.surround(tokens, |tokens| {
+ self.elems.to_tokens(tokens);
+ });
+ }
+ }
+
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+ impl ToTokens for PatStruct {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ tokens.append_all(self.attrs.outer());
+ path::printing::print_path(tokens, &self.qself, &self.path);
+ self.brace_token.surround(tokens, |tokens| {
+ self.fields.to_tokens(tokens);
+ // NOTE: We need a comma before the dot2 token if it is present.
+ if !self.fields.empty_or_trailing() && self.rest.is_some() {
+ <Token![,]>::default().to_tokens(tokens);
+ }
+ self.rest.to_tokens(tokens);
+ });
+ }
+ }
+
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+ impl ToTokens for PatTuple {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ tokens.append_all(self.attrs.outer());
+ self.paren_token.surround(tokens, |tokens| {
+ self.elems.to_tokens(tokens);
+ // If there is only one element, a trailing comma is needed to
+ // distinguish PatTuple from PatParen, unless this is `(..)`
+ // which is a tuple pattern even without comma.
+ if self.elems.len() == 1
+ && !self.elems.trailing_punct()
+ && !matches!(self.elems[0], Pat::Rest { .. })
+ {
+ <Token![,]>::default().to_tokens(tokens);
+ }
+ });
+ }
+ }
+
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+ impl ToTokens for PatTupleStruct {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ tokens.append_all(self.attrs.outer());
+ path::printing::print_path(tokens, &self.qself, &self.path);
+ self.paren_token.surround(tokens, |tokens| {
+ self.elems.to_tokens(tokens);
+ });
+ }
+ }
+
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+ impl ToTokens for PatType {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ tokens.append_all(self.attrs.outer());
+ self.pat.to_tokens(tokens);
+ self.colon_token.to_tokens(tokens);
+ self.ty.to_tokens(tokens);
+ }
+ }
+
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+ impl ToTokens for PatWild {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ tokens.append_all(self.attrs.outer());
+ self.underscore_token.to_tokens(tokens);
+ }
+ }
+
+ #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+ impl ToTokens for FieldPat {
+ fn to_tokens(&self, tokens: &mut TokenStream) {
+ tokens.append_all(self.attrs.outer());
+ if let Some(colon_token) = &self.colon_token {
+ self.member.to_tokens(tokens);
+ colon_token.to_tokens(tokens);
+ }
+ self.pat.to_tokens(tokens);
+ }
+ }
+}
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