Enum rustc_ast::ast::PatKind

pub enum PatKind {
    Wild,
    Ident(BindingMode, Ident, Option<P<Pat>>),
    Struct(Option<QSelf>, Path, Vec<PatField>, bool),
    TupleStruct(Option<QSelf>, Path, Vec<P<Pat>>),
    Or(Vec<P<Pat>>),
    Path(Option<QSelf>, Path),
    Tuple(Vec<P<Pat>>),
    Box(P<Pat>),
    Ref(P<Pat>, Mutability),
    Lit(P<Expr>),
    Range(Option<P<Expr>>, Option<P<Expr>>, Spanned<RangeEnd>),
    Slice(Vec<P<Pat>>),
    Rest,
    Paren(P<Pat>),
    MacCall(MacCall),
}

All the different flavors of pattern that Rust recognizes.

Variants

Wild

Represents a wildcard pattern (_).

Ident(BindingMode, Ident, Option<P<Pat>>)

A PatKind::Ident may either be a new bound variable (ref mut binding @ OPT_SUBPATTERN), or a unit struct/variant pattern, or a const pattern (in the last two cases the third field must be None). Disambiguation cannot be done with parser alone, so it happens during name resolution.

Tuple Fields of Ident

0: BindingMode1: Ident2: Option<P<Pat>>

Struct(Option<QSelf>, Path, Vec<PatField>, bool)

A struct or struct variant pattern (e.g., Variant {x, y, ..}). The bool is true in the presence of a ...

Tuple Fields of Struct

0: Option<QSelf>1: Path2: Vec<PatField>3: bool

TupleStruct(Option<QSelf>, Path, Vec<P<Pat>>)

A tuple struct/variant pattern (Variant(x, y, .., z)).

Tuple Fields of TupleStruct

0: Option<QSelf>1: Path2: Vec<P<Pat>>

Or(Vec<P<Pat>>)

An or-pattern A | B | C. Invariant: pats.len() >= 2.

Tuple Fields of Or

0: Vec<P<Pat>>

Path(Option<QSelf>, Path)

A possibly qualified path pattern. Unqualified path patterns A::B::C can legally refer to variants, structs, constants or associated constants. Qualified path patterns <A>::B::C/<A as Trait>::B::C can only legally refer to associated constants.

Tuple Fields of Path

0: Option<QSelf>1: Path

Tuple(Vec<P<Pat>>)

A tuple pattern ((a, b)).

Tuple Fields of Tuple

0: Vec<P<Pat>>

Box(P<Pat>)

A box pattern.

Tuple Fields of Box

0: P<Pat>

Ref(P<Pat>, Mutability)

A reference pattern (e.g., &mut (a, b)).

Tuple Fields of Ref

0: P<Pat>1: Mutability

Lit(P<Expr>)

A literal.

Tuple Fields of Lit

0: P<Expr>

Range(Option<P<Expr>>, Option<P<Expr>>, Spanned<RangeEnd>)

A range pattern (e.g., 1...2, 1..2, 1.., ..2, 1..=2, ..=2).

Tuple Fields of Range

0: Option<P<Expr>>1: Option<P<Expr>>2: Spanned<RangeEnd>

Slice(Vec<P<Pat>>)

A slice pattern [a, b, c].

Tuple Fields of Slice

0: Vec<P<Pat>>

Rest

A rest pattern ...

Syntactically it is valid anywhere.

Semantically however, it only has meaning immediately inside:

• a slice pattern: [a, .., b],
• a binding pattern immediately inside a slice pattern: [a, r @ ..],
• a tuple pattern: (a, .., b),
• a tuple struct/variant pattern: $path(a, .., b).

In all of these cases, an additional restriction applies, only one rest pattern may occur in the pattern sequences.

Paren(P<Pat>)

Parentheses in patterns used for grouping (i.e., (PAT)).

Tuple Fields of Paren

0: P<Pat>

MacCall(MacCall)

A macro pattern; pre-expansion.

Tuple Fields of MacCall

0: MacCall

Trait Implementations

impl Clone for PatKind

fn clone(&self) -> PatKind

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PatKind

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<__D: Decoder> Decodable<__D> for PatKind

fn decode(__decoder: &mut __D) -> Result<Self, <__D as Decoder>::Error>

impl<__E: Encoder> Encodable<__E> for PatKind

fn encode(&self, __encoder: &mut __E) -> Result<(), <__E as Encoder>::Error>

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference’s “Type Layout” chapter for details on type layout guarantees.

Size: 96 bytes

Size for each variant:

• Wild: 0 bytes
• Ident: 23 bytes
• Struct: 95 bytes
• TupleStruct: 95 bytes
• Or: 31 bytes
• Path: 71 bytes
• Tuple: 31 bytes
• Box: 15 bytes
• Ref: 15 bytes
• Lit: 15 bytes
• Range: 31 bytes
• Slice: 31 bytes
• Rest: 0 bytes
• Paren: 15 bytes
• MacCall: 71 bytes