# Struct rustc_pattern_analysis::pat_column::PatternColumn

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    pub struct PatternColumn<'p, Cx: PatCx> {
        patterns: Vec<&'p DeconstructedPat<Cx>>,
    }

Expand description

A column of patterns in a match, where a column is the intuitive notion of “subpatterns that inspect the same subvalue/place”. This is used to traverse patterns column-by-column for lints. Despite similarities with the algorithm in `crate::usefulness`, this does a different traversal. Notably this is linear in the depth of patterns, whereas `compute_exhaustiveness_and_usefulness` is worst-case exponential (exhaustiveness is NP-complete). The core difference is that we treat sub-columns separately.

This is not used in the usefulness algorithm; only in lints.

## Fields§

§`patterns: Vec<&'p DeconstructedPat<Cx>>`

This must not contain an or-pattern. `expand_and_push` takes care to expand them.

## Implementations§

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### impl<'p, Cx: PatCx> PatternColumn<'p, Cx>

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#### pub fn new(arms: &[MatchArm<'p, Cx>]) -> Self

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#### fn expand_and_push(&mut self, pat: PatOrWild<'p, Cx>)

Pushes a pattern onto the column, expanding any or-patterns into its subpatterns. Internal method, prefer `PatternColumn::new`.

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#### pub fn head_ty(&self) -> Option<&Cx::Ty>

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

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#### pub fn analyze_ctors( &self, cx: &Cx, ty: &Cx::Ty ) -> Result<SplitConstructorSet<Cx>, Cx::Error>

Do constructor splitting on the constructors of the column.

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#### pub fn specialize( &self, cx: &Cx, ty: &Cx::Ty, ctor: &Constructor<Cx> ) -> Vec<PatternColumn<'p, Cx>>

Does specialization: given a constructor, this takes the patterns from the column that match the constructor, and outputs their fields. This returns one column per field of the constructor. They usually all have the same length (the number of patterns in `self` that matched `ctor`), except that we expand or-patterns which may change the lengths.

## Trait Implementations§

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### impl<'p, Cx: Debug + PatCx> Debug for PatternColumn<'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> DynSend for PatternColumn<'p, Cx>
where <Cx as PatCx>::Ty: DynSync, <Cx as PatCx>::PatData: DynSync, <Cx as PatCx>::VariantIdx: DynSync, <Cx as PatCx>::StrLit: DynSync,

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### impl<'p, Cx> DynSync for PatternColumn<'p, Cx>
where <Cx as PatCx>::Ty: DynSync, <Cx as PatCx>::PatData: DynSync, <Cx as PatCx>::VariantIdx: DynSync, <Cx as PatCx>::StrLit: DynSync,

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### impl<'p, Cx> Freeze for PatternColumn<'p, Cx>

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### impl<'p, Cx> RefUnwindSafe for PatternColumn<'p, Cx>
where <Cx as PatCx>::Ty: RefUnwindSafe, <Cx as PatCx>::PatData: RefUnwindSafe, <Cx as PatCx>::VariantIdx: RefUnwindSafe, <Cx as PatCx>::StrLit: RefUnwindSafe,

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### impl<'p, Cx> Send for PatternColumn<'p, Cx>
where <Cx as PatCx>::Ty: Sync, <Cx as PatCx>::PatData: Sync, <Cx as PatCx>::VariantIdx: Sync, <Cx as PatCx>::StrLit: Sync,

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### impl<'p, Cx> Sync for PatternColumn<'p, Cx>
where <Cx as PatCx>::Ty: Sync, <Cx as PatCx>::PatData: Sync, <Cx as PatCx>::VariantIdx: Sync, <Cx as PatCx>::StrLit: Sync,

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

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### impl<'p, Cx> UnwindSafe for PatternColumn<'p, Cx>
where <Cx as PatCx>::Ty: RefUnwindSafe, <Cx as PatCx>::PatData: RefUnwindSafe, <Cx as PatCx>::VariantIdx: RefUnwindSafe, <Cx as PatCx>::StrLit: RefUnwindSafe,

## Blanket Implementations§

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### impl<T> Aligned for T

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#### const ALIGN: Alignment = _

Alignment of `Self`.
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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, R> CollectAndApply<T, R> for T

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#### fn collect_and_apply<I, F>(iter: I, f: F) -> R
where I: Iterator<Item = T>, F: FnOnce(&[T]) -> R,

Equivalent to `f(&iter.collect::<Vec<_>>())`.

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#### type Output = R

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### impl<T> Filterable for T

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#### fn filterable( self, filter_name: &'static str ) -> RequestFilterDataProvider<T, fn(_: DataRequest<'_>) -> bool>

Creates a filterable data provider with the given name for debugging. 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> Instrument for T

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#### fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided `Span`, returning an `Instrumented` wrapper. Read more
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#### fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current `Span`, returning an `Instrumented` wrapper. Read more
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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<P> IntoQueryParam<P> for P

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#### fn into_query_param(self) -> P

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### impl<T> MaybeResult<T> for T

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#### type Error = !

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#### fn from(_: Result<T, <T as MaybeResult<T>>::Error>) -> T

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#### fn to_result(self) -> Result<T, <T as MaybeResult<T>>::Error>

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### impl<T> Pointable for T

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#### const ALIGN: usize = _

The alignment of pointer.
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#### type Init = T

The type for initializers.
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#### unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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#### unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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#### unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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#### unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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### impl<T> Same for T

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#### type Output = T

Should always be `Self`
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### impl<'tcx, T> ToPredicate<'tcx, T> for T

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#### fn to_predicate(self, _tcx: TyCtxt<'tcx>) -> T

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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<V, T> VZip<V> for T
where V: MultiLane<T>,

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#### fn vzip(self) -> V

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### impl<Tcx, T> Value<Tcx> for T
where Tcx: DepContext,

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#### default fn from_cycle_error( tcx: Tcx, cycle_error: &CycleError, _guar: ErrorGuaranteed ) -> T

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### impl<T> WithSubscriber for T

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#### fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided `Subscriber` to this type, returning a `WithDispatch` wrapper. Read more
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#### fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default `Subscriber` to this type, returning a `WithDispatch` wrapper. Read more
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### impl<'a, T> Captures<'a> for T
where T: ?Sized,

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### impl<'a, T> Captures<'a> for T
where T: ?Sized,

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### impl<T> ErasedDestructor for T
where T: 'static,

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### impl<T> MaybeSendSync for T
where T: Send + Sync,

## 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: 24 bytes