Struct rustc_mir::borrow_check::region_infer::values::RegionValues

pub(crate) struct RegionValues<N: Idx> {
    elements: Rc<RegionValueElements>,
    placeholder_indices: Rc<PlaceholderIndices>,
    points: SparseBitMatrix<N, PointIndex>,
    free_regions: SparseBitMatrix<N, RegionVid>,
    placeholders: SparseBitMatrix<N, PlaceholderIndex>,
}

Stores the full values for a set of regions (in contrast to LivenessValues, which only stores those points in the where a region is live). The full value for a region may contain points in the CFG, but also free regions as well as bound universe placeholders.

Example:

fn foo(x: &'a u32) -> &'a u32 {
   let y: &'0 u32 = x; // let's call this `'0`
   y
}

Here, the variable '0 would contain the free region 'a, because (since it is returned) it must live for at least 'a. But it would also contain various points from within the function.

Fields

elements: Rc<RegionValueElements>

placeholder_indices: Rc<PlaceholderIndices>

points: SparseBitMatrix<N, PointIndex>

free_regions: SparseBitMatrix<N, RegionVid>

placeholders: SparseBitMatrix<N, PlaceholderIndex>

Placeholders represent bound regions – so something like 'a in for<’a> fn(&’a u32)`.

Implementations

impl<N: Idx> RegionValues<N>

pub(crate) fn new(
    elements: &Rc<RegionValueElements>,
    num_universal_regions: usize,
    placeholder_indices: &Rc<PlaceholderIndices>
) -> Self

Creates a new set of “region values” that tracks causal information. Each of the regions in num_region_variables will be initialized with an empty set of points and no causal information.

pub(crate) fn add_element(&mut self, r: N, elem: impl ToElementIndex) -> bool

Adds the given element to the value for the given region. Returns whether the element is newly added (i.e., was not already present).

pub(crate) fn add_all_points(&mut self, r: N)

Adds all the control-flow points to the values for r.

pub(crate) fn add_region(&mut self, r_to: N, r_from: N) -> bool

Adds all elements in r_from to r_to (because e.g., r_to: r_from).

pub(crate) fn contains(&self, r: N, elem: impl ToElementIndex) -> bool

Returns true if the region r contains the given element.

pub(crate) fn merge_liveness<M: Idx>(
    &mut self,
    to: N,
    from: M,
    values: &LivenessValues<M>
)

self[to] |= values[from], essentially: that is, take all the elements for the region from from values and add them to the region to in self.

pub(crate) fn contains_points(&self, sup_region: N, sub_region: N) -> bool

Returns true if sup_region contains all the CFG points that sub_region contains. Ignores universal regions.

pub(crate) fn locations_outlived_by<'a>(
    &'a self,
    r: N
) -> impl Iterator<Item = Location> + 'a

Returns the locations contained within a given region r.

pub(crate) fn universal_regions_outlived_by<'a>(
    &'a self,
    r: N
) -> impl Iterator<Item = RegionVid> + 'a

Returns just the universal regions that are contained in a given region’s value.

pub(crate) fn placeholders_contained_in<'a>(
    &'a self,
    r: N
) -> impl Iterator<Item = PlaceholderRegion> + 'a

Returns all the elements contained in a given region’s value.

pub(crate) fn elements_contained_in<'a>(
    &'a self,
    r: N
) -> impl Iterator<Item = RegionElement> + 'a

Returns all the elements contained in a given region’s value.

pub(crate) fn region_value_str(&self, r: N) -> String

Returns a “pretty” string value of the region. Meant for debugging.

Trait Implementations

impl<N: Clone + Idx> Clone for RegionValues<N>

fn clone(&self) -> RegionValues<N>

Returns a copy of the value.

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

Performs copy-assignment from source.