Enum rustc_middle::thir::PatKind

pub enum PatKind<'tcx> {
    Wild,
    AscribeUserType {
        ascription: Ascription<'tcx>,
        subpattern: Box<Pat<'tcx>>,
    },
    Binding {
        mutability: Mutability,
        name: Symbol,
        mode: BindingMode,
        var: LocalVarId,
        ty: Ty<'tcx>,
        subpattern: Option<Box<Pat<'tcx>>>,
        is_primary: bool,
    },
    Variant {
        adt_def: AdtDef<'tcx>,
        args: GenericArgsRef<'tcx>,
        variant_index: VariantIdx,
        subpatterns: Vec<FieldPat<'tcx>>,
    },
    Leaf {
        subpatterns: Vec<FieldPat<'tcx>>,
    },
    Deref {
        subpattern: Box<Pat<'tcx>>,
    },
    Constant {
        value: Const<'tcx>,
    },
    InlineConstant {
        def: LocalDefId,
        subpattern: Box<Pat<'tcx>>,
    },
    Range(Box<PatRange<'tcx>>),
    Slice {
        prefix: Box<[Box<Pat<'tcx>>]>,
        slice: Option<Box<Pat<'tcx>>>,
        suffix: Box<[Box<Pat<'tcx>>]>,
    },
    Array {
        prefix: Box<[Box<Pat<'tcx>>]>,
        slice: Option<Box<Pat<'tcx>>>,
        suffix: Box<[Box<Pat<'tcx>>]>,
    },
    Or {
        pats: Box<[Box<Pat<'tcx>>]>,
    },
    Error(ErrorGuaranteed),
}

Variants

Wild

A wildcard pattern: _.

AscribeUserType

Fields

ascription: Ascription<'tcx>

subpattern: Box<Pat<'tcx>>

Binding

Fields

mutability: Mutability

name: Symbol

mode: BindingMode

var: LocalVarId

ty: Ty<'tcx>

subpattern: Option<Box<Pat<'tcx>>>

is_primary: bool

Is this the leftmost occurrence of the binding, i.e., is var the HirId of this pattern?

x, ref x, x @ P, etc.

Variant

Fields

adt_def: AdtDef<'tcx>

args: GenericArgsRef<'tcx>

variant_index: VariantIdx

subpatterns: Vec<FieldPat<'tcx>>

Foo(...) or Foo{...} or Foo, where Foo is a variant name from an ADT with multiple variants.

Leaf

Fields

subpatterns: Vec<FieldPat<'tcx>>

(...), Foo(...), Foo{...}, or Foo, where Foo is a variant name from an ADT with a single variant.

Deref

Fields

subpattern: Box<Pat<'tcx>>

box P, &P, &mut P, etc.

Constant

Fields

value: Const<'tcx>

One of the following:

• &str (represented as a valtree), which will be handled as a string pattern and thus exhaustiveness checking will detect if you use the same string twice in different patterns.
• integer, bool, char or float (represented as a valtree), which will be handled by exhaustiveness to cover exactly its own value, similar to &str, but these values are much simpler.
• Opaque constants (represented as mir::ConstValue), that must not be matched structurally. So anything that does not derive PartialEq and Eq.

These are always compared with the matched place using (the semantics of) PartialEq.

InlineConstant

Fields

def: LocalDefId

LocalDefId of the constant, we need this so that we have a reference that can be used by unsafety checking to visit nested unevaluated constants.

subpattern: Box<Pat<'tcx>>

If the inline constant is used in a range pattern, this subpattern represents the range (if both ends are inline constants, there will be multiple InlineConstant wrappers).

Otherwise, the actual pattern that the constant lowered to. As with other constants, inline constants are matched structurally where possible.

Inline constant found while lowering a pattern.

Range(Box<PatRange<'tcx>>)

Slice

Fields

prefix: Box<[Box<Pat<'tcx>>]>

slice: Option<Box<Pat<'tcx>>>

suffix: Box<[Box<Pat<'tcx>>]>

Matches against a slice, checking the length and extracting elements. irrefutable when there is a slice pattern and both prefix and suffix are empty. e.g., &[ref xs @ ..].

Array

Fields

prefix: Box<[Box<Pat<'tcx>>]>

slice: Option<Box<Pat<'tcx>>>

suffix: Box<[Box<Pat<'tcx>>]>

Fixed match against an array; irrefutable.

Or

Fields

pats: Box<[Box<Pat<'tcx>>]>

An or-pattern, e.g. p | q. Invariant: pats.len() >= 2.

Error(ErrorGuaranteed)

An error has been encountered during lowering. We probably shouldn’t report more lints related to this pattern.

Trait Implementations

impl<'tcx> Clone for PatKind<'tcx>

fn clone(&self) -> PatKind<'tcx>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'tcx> Debug for PatKind<'tcx>

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

Formats the value using the given formatter.

impl<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for PatKind<'tcx>

fn hash_stable( &self, __hcx: &mut StableHashingContext<'__ctx>, __hasher: &mut StableHasher )

impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for PatKind<'tcx>

fn visit_with<__V: TypeVisitor<TyCtxt<'tcx>>>( &self, __visitor: &mut __V ) -> ControlFlow<__V::BreakTy>

The entry point for visiting. To visit a value t with a visitor v call: t.visit_with(v).

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: 48 bytes

Size for each variant:

• Wild: 0 bytes
• AscribeUserType: 47 bytes
• Binding: 31 bytes
• Variant: 47 bytes
• Leaf: 31 bytes
• Deref: 15 bytes
• Constant: 47 bytes
• InlineConstant: 15 bytes
• Range: 15 bytes
• Slice: 47 bytes
• Array: 47 bytes
• Or: 23 bytes
• Error: 0 bytes