Struct chalk_solve::infer::var::EnaVariable

pub struct EnaVariable<I: Interner> {
    var: InferenceVar,
    phantom: PhantomData<I>,
}

Wrapper around chalk_ir::InferenceVar for coherence purposes. An inference variable represents an unknown term – either a type or a lifetime. The variable itself is just an index into the unification table; the unification table maps it to an InferenceValue.

Inference variables can be in one of two states (represents by the variants of an InferenceValue):

• Unbound(ui). In this case, the value of the variable is not yet known. We carry along a universe index ui that tracks the universe in which the variable was created; this determines what names may appear in the variable’s value.
  • In this state, we do not track the kind of this variable (i.e., whether it represents a type or a lifetime). There is no need: if it represents a lifetime, for example, then there should only ever be constraints that relate it to other lifetimes, or use it in lifetime position.
• Bound. In this case, the value of the variable is known. We carry along the value. We discard the universe index in which the variable was created, since that was only needed to help us reject illegal values. Once the value of a variable is known, it can never change.
  • The value we actually store for variables is a ir::GenericArg, and hence it does carry along the kind of the variable via the enum variant. However, we should always know the kind of the variable from context, and hence we typically “downcast” the resulting variable using e.g. value.ty().unwrap().

Fields

var: InferenceVar

phantom: PhantomData<I>

Implementations

impl<I: Interner> EnaVariable<I>

pub fn to_ty_with_kind(self, interner: I, kind: TyVariableKind) -> Ty<I>

Convert this inference variable into a type. When using this method, naturally you should know from context that the kind of this inference variable is a type (we can’t check it).

pub fn to_ty(self, interner: I) -> Ty<I>

Same as to_ty_with_kind, but the kind is set to TyVariableKind::General. This should be used instead of to_ty_with_kind when creating a new inference variable (when the kind is not known).

pub fn to_lifetime(self, interner: I) -> Lifetime<I>

Convert this inference variable into a lifetime. When using this method, naturally you should know from context that the kind of this inference variable is a lifetime (we can’t check it).

pub fn to_const(self, interner: I, ty: Ty<I>) -> Const<I>

Convert this inference variable into a const. When using this method, naturally you should know from context that the kind of this inference variable is a const (we can’t check it).

Trait Implementations

impl<I: Clone + Interner> Clone for EnaVariable<I>

fn clone(&self) -> EnaVariable<I>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<I: Interner> Debug for EnaVariable<I>

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

Formats the value using the given formatter.

impl<I: Interner> From<EnaVariable<I>> for InferenceVar

fn from(ena_var: EnaVariable<I>) -> InferenceVar

Converts to this type from the input type.

impl<I: Interner> From<InferenceVar> for EnaVariable<I>

fn from(var: InferenceVar) -> EnaVariable<I>

Converts to this type from the input type.

impl<I: Hash + Interner> Hash for EnaVariable<I>

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<I: Ord + Interner> Ord for EnaVariable<I>

fn cmp(&self, other: &EnaVariable<I>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized + PartialOrd,

Restrict a value to a certain interval.

impl<I: PartialEq + Interner> PartialEq for EnaVariable<I>

fn eq(&self, other: &EnaVariable<I>) -> bool

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

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

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<I: PartialOrd + Interner> PartialOrd for EnaVariable<I>

fn partial_cmp(&self, other: &EnaVariable<I>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

This method tests less than (for self and other) and is used by the < operator.

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

This method tests less than or equal to (for self and other) and is used by the <= operator.

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

This method tests greater than (for self and other) and is used by the > operator.

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

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<I: Interner> UnifyKey for EnaVariable<I>

type Value = InferenceValue<I>

fn index(&self) -> u32

fn from_index(u: u32) -> Self

fn tag() -> &'static str

fn order_roots( a: Self, a_value: &Self::Value, b: Self, b_value: &Self::Value ) -> Option<(Self, Self)>

You should return first the key that should be used as root, then the other key (that will then point to the new root).

impl<I: Copy + Interner> Copy for EnaVariable<I>

impl<I: Eq + Interner> Eq for EnaVariable<I>

impl<I: Interner> StructuralPartialEq for EnaVariable<I>