# Struct chalk_ir::BoundVar

``````pub struct BoundVar {
pub debruijn: DebruijnIndex,
pub index: usize,
}``````
Expand description

Identifies a particular bound variable within a binder. Variables are identified by the combination of a `DebruijnIndex`, which identifies the binder, and an index within that binder.

Consider this case:

``forall<'a, 'b> { forall<'c, 'd> { ... } }``

Within the `...` term:

• the variable `'a` have a debruijn index of 1 and index 0
• the variable `'b` have a debruijn index of 1 and index 1
• the variable `'c` have a debruijn index of 0 and index 0
• the variable `'d` have a debruijn index of 0 and index 1

The variables `'a` and `'b` both have debruijn index of 1 because, counting out, they are the 2nd binder enclosing `...`. The indices identify the location within that binder.

The variables `'c` and `'d` both have debruijn index of 0 because they appear in the innermost binder enclosing the `...`. The indices identify the location within that binder.

## Fields§

§`debruijn: DebruijnIndex`

Debruijn index, which identifies the binder.

§`index: usize`

Index within the binder.

## Implementations§

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### impl BoundVar

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#### pub fn new(debruijn: DebruijnIndex, index: usize) -> Self

Creates a new bound variable.

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

Casts the bound variable to a type.

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Wrap the bound variable in a lifetime.

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

Wraps the bound variable in a constant.

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#### pub fn bound_within(self, outer_binder: DebruijnIndex) -> bool

True if this variable is bound within the `amount` innermost binders.

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#### pub fn shifted_in(self) -> Self

Adjusts the debruijn index (see `DebruijnIndex::shifted_in`).

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#### pub fn shifted_in_from(self, outer_binder: DebruijnIndex) -> Self

Adjusts the debruijn index (see `DebruijnIndex::shifted_in`).

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#### pub fn shifted_out(self) -> Option<Self>

Adjusts the debruijn index (see `DebruijnIndex::shifted_in`).

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#### pub fn shifted_out_to(self, outer_binder: DebruijnIndex) -> Option<Self>

Adjusts the debruijn index (see `DebruijnIndex::shifted_in`).

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#### pub fn index_if_innermost(self) -> Option<usize>

Return the index of the bound variable, but only if it is bound at the innermost binder. Otherwise, returns `None`.

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#### pub fn index_if_bound_at(self, debruijn: DebruijnIndex) -> Option<usize>

Return the index of the bound variable, but only if it is bound at the innermost binder. Otherwise, returns `None`.

## Trait Implementations§

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### impl Clone for BoundVar

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

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 Debug for BoundVar

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

Formats the value using the given formatter. Read more
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### impl Hash for BoundVar

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

Feeds this value into the given `Hasher`. Read more
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#### fn hash_slice<H>(data: &[Self], state: &mut H)where H: Hasher, Self: Sized,

Feeds a slice of this type into the given `Hasher`. Read more
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### impl Ord for BoundVar

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#### fn cmp(&self, other: &BoundVar) -> Ordering

This method returns an `Ordering` between `self` and `other`. Read more
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#### fn max(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the maximum of two values. Read more
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#### fn min(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the minimum of two values. Read more
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#### fn clamp(self, min: Self, max: Self) -> Selfwhere Self: Sized + PartialOrd,

Restrict a value to a certain interval. Read more
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### impl PartialEq for BoundVar

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#### fn eq(&self, other: &BoundVar) -> bool

This method tests for `self` and `other` values to be equal, and is used by `==`.
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#### 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.
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### impl PartialOrd for BoundVar

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#### fn partial_cmp(&self, other: &BoundVar) -> Option<Ordering>

This method returns an ordering between `self` and `other` values if one exists. Read more
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#### fn lt(&self, other: &Rhs) -> bool

This method tests less than (for `self` and `other`) and is used by the `<` operator. Read more
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#### fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for `self` and `other`) and is used by the `<=` operator. Read more
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#### fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for `self` and `other`) and is used by the `>` operator. Read more
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#### fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for `self` and `other`) and is used by the `>=` operator. Read more
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## Blanket Implementations§

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### impl<T> Any for Twhere 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 Twhere 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 Twhere 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> Cast for T

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#### fn cast<U>(self, interner: U::Interner) -> Uwhere Self: CastTo<U>, U: HasInterner,

Cast a value to type `U` using `CastTo`.
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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 Twhere 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 Twhere 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 Twhere 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 Twhere 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.