# Struct rustc_pattern_analysis::usefulness::PatStack

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    struct PatStack<'p, Cx: TypeCx> {
        pats: SmallVec<[&'p DeconstructedPat<'p, Cx>; 2]>,
        relevant: bool,
    }

Expand description

Represents a pattern-tuple under investigation.

## Fields§

§`pats: SmallVec<[&'p DeconstructedPat<'p, Cx>; 2]>`§`relevant: bool`

Sometimes we know that as far as this row is concerned, the current case is already handled by a different, more general, case. When the case is irrelevant for all rows this allows us to skip a case entirely. This is purely an optimization. See at the top for details.

## Implementations§

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### impl<'p, Cx: TypeCx> PatStack<'p, Cx>

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#### fn from_pattern(pat: &'p DeconstructedPat<'p, Cx>) -> Self

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#### fn is_empty(&self) -> bool

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#### fn len(&self) -> usize

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#### fn head_opt(&self) -> Option<&'p DeconstructedPat<'p, Cx>>

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#### fn head(&self) -> &'p DeconstructedPat<'p, Cx>

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#### fn iter( &self ) -> impl Iterator<Item = &'p DeconstructedPat<'p, Cx>> + Captures<'_>

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#### fn expand_or_pat(&self) -> impl Iterator<Item = PatStack<'p, Cx>> + Captures<'_>

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#### fn pop_head_constructor( &self, pcx: &PlaceCtxt<'_, 'p, Cx>, ctor: &Constructor<Cx>, ctor_sub_tys: &[Cx::Ty], ctor_is_relevant: bool ) -> PatStack<'p, Cx>

This computes `specialize(ctor, self)`. See top of the file for explanations. Only call if `ctor.is_covered_by(self.head().ctor())` is true.

## Trait Implementations§

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### impl<'p, Cx: TypeCx> Clone for PatStack<'p, Cx>

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#### fn clone(&self) -> Self

Returns a copy of the value. Read more
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#### fn clone_from(&mut self, source: &Self)

Performs copy-assignment from `source`. Read more
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### impl<'p, Cx: TypeCx> Debug for PatStack<'p, Cx>

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

Formats the value using the given formatter. Read more

## Auto Trait Implementations§

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### impl<'p, Cx> !RefUnwindSafe for PatStack<'p, Cx>

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### impl<'p, Cx> !Send for PatStack<'p, Cx>

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### impl<'p, Cx> !Sync for PatStack<'p, Cx>

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### impl<'p, Cx> Unpin for PatStack<'p, Cx>

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### impl<'p, Cx> !UnwindSafe for PatStack<'p, Cx>

## Blanket Implementations§

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### impl<T> Any for T
where T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> Borrow<T> for T
where T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for T
where T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for T
where U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T> ToOwned for T
where T: Clone,

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#### type Owned = T

The resulting type after obtaining ownership.
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#### fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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#### fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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### impl<T, U> TryFrom<U> for T
where U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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### impl<'a, T> Captures<'a> for T
where T: ?Sized,

## 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: 32 bytes