Enum ConstructorSet

pub enum ConstructorSet<Cx: PatCx> {
    Struct {
        empty: bool,
    },
    Variants {
        variants: IndexVec<Cx::VariantIdx, VariantVisibility>,
        non_exhaustive: bool,
    },
    Ref,
    Union,
    Bool,
    Integers {
        range_1: IntRange,
        range_2: Option<IntRange>,
    },
    Slice {
        array_len: Option<usize>,
        subtype_is_empty: bool,
    },
    Unlistable,
    NoConstructors,
}

Describes the set of all constructors for a type. For details, in particular about the emptiness of constructors, see the top of the file.

In terms of division of responsibility, ConstructorSet::split handles all of the exhaustive_patterns feature.

Variants

Struct

The type is a tuple or struct. empty tracks whether the type is empty.

Fields

empty: bool

Variants

This type has the following list of constructors. If variants is empty and non_exhaustive is false, don’t use this; use NoConstructors instead.

Fields

variants: IndexVec<Cx::VariantIdx, VariantVisibility>

non_exhaustive: bool

Ref

The type is &T.

Union

The type is a union.

Bool

Booleans.

Integers

The type is spanned by integer values. The range or ranges give the set of allowed values. The second range is only useful for char.

Fields

range_1: IntRange

range_2: Option<IntRange>

Slice

The type is matched by slices. array_len is the compile-time length of the array, if known. If subtype_is_empty, all constructors are empty except possibly the zero-length slice [].

Fields

array_len: Option<usize>

subtype_is_empty: bool

Unlistable

The constructors cannot be listed, and the type cannot be matched exhaustively. E.g. str, floats.

NoConstructors

The type has no constructors (not even empty ones). This is ! and empty enums.

Implementations

impl<Cx: PatCx> ConstructorSet<Cx>

pub fn split<'a>( &self, ctors: impl Iterator<Item = &'a Constructor<Cx>> + Clone, ) -> SplitConstructorSet<Cx>

where Cx: 'a,

This analyzes a column of constructors to 1/ determine which constructors of the type (if any) are missing; 2/ split constructors to handle non-trivial intersections e.g. on ranges or slices. This can get subtle; see SplitConstructorSet for details of this operation and its invariants.

Trait Implementations

impl<Cx: Debug + PatCx> Debug for ConstructorSet<Cx>

where Cx::VariantIdx: Debug,

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

Formats the value using the given formatter.