Struct rustc_mir_build::thir::pattern::usefulness::PatStack

struct PatStack<'p, 'tcx> {
    pats: SmallVec<[&'p Pat<'tcx>; 2]>,
    head_ctor: OnceCell<Constructor<'tcx>>,
}

A row of a matrix. Rows of len 1 are very common, which is why SmallVec[_; 2] works well.

Fields

pats: SmallVec<[&'p Pat<'tcx>; 2]>

head_ctor: OnceCell<Constructor<'tcx>>

Cache for the constructor of the head

Implementations

impl<'p, 'tcx> PatStack<'p, 'tcx>

fn from_pattern(pat: &'p Pat<'tcx>) -> Self

fn from_vec(vec: SmallVec<[&'p Pat<'tcx>; 2]>) -> Self

fn is_empty(&self) -> bool

fn len(&self) -> usize

fn head(&self) -> &'p Pat<'tcx>

fn head_ctor<'a>(
    &'a self,
    cx: &MatchCheckCtxt<'p, 'tcx>
) -> &'a Constructor<'tcx>

fn iter(&self) -> impl Iterator<Item = &Pat<'tcx>>

fn expand_or_pat<'a>(
    &'a self
) -> impl Iterator<Item = PatStack<'p, 'tcx>> + Captures<'a>

fn pop_head_constructor(
    &self,
    ctor_wild_subpatterns: &Fields<'p, 'tcx>
) -> PatStack<'p, 'tcx>

This computes S(self.head_ctor(), self). See top of the file for explanations.

Structure patterns with a partial wild pattern (Foo { a: 42, .. }) have their missing fields filled with wild patterns.

This is roughly the inverse of Constructor::apply.

Trait Implementations

impl<'p, 'tcx> Clone for PatStack<'p, 'tcx>

fn clone(&self) -> PatStack<'p, 'tcx>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'p, 'tcx> Debug for PatStack<'p, 'tcx>

Pretty-printing for matrix row.

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

Formats the value using the given formatter.

impl<'p, 'tcx> Default for PatStack<'p, 'tcx>

fn default() -> Self

Returns the “default value” for a type.

impl<'p, 'tcx> FromIterator<&'p Pat<'tcx>> for PatStack<'p, 'tcx>

fn from_iter<T>(iter: T) -> Self where
    T: IntoIterator<Item = &'p Pat<'tcx>>, 

Creates a value from an iterator.

impl<'p, 'tcx> FromIterator<PatStack<'p, 'tcx>> for Matrix<'p, 'tcx>

fn from_iter<T>(iter: T) -> Self where
    T: IntoIterator<Item = PatStack<'p, 'tcx>>, 

Creates a value from an iterator.

impl<'p, 'tcx> PartialEq<PatStack<'p, 'tcx>> for PatStack<'p, 'tcx>

fn eq(&self, other: &Self) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.