Enum rustc_pattern_analysis::constructor::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.

pub(crate) fn all_empty(&self) -> bool

Whether this set only contains empty constructors.

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.

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: 128 bytes

Size for each variant:

• Struct: 17 bytes
• Variants: 48 bytes
• Ref: 0 bytes
• Union: 0 bytes
• Bool: 0 bytes
• Integers: 128 bytes
• Slice: 40 bytes
• Unlistable: 0 bytes
• NoConstructors: 0 bytes