Struct rustc_data_structures::bitvec::BitMatrix

pub struct BitMatrix<R: Idx, C: Idx> { /* fields omitted */ }

A "bit matrix" is basically a matrix of booleans represented as one gigantic bitvector. In other words, it is as if you have rows bitvectors, each of length columns.

Methods

impl<R: Idx, C: Idx> BitMatrix<R, C>

pub fn new(rows: usize, columns: usize) -> BitMatrix<R, C>

Create a new rows x columns matrix, initially empty.

pub fn add(&mut self, row: R, column: R) -> bool

Sets the cell at (row, column) to true. Put another way, add column to the bitset for row.

Returns true if this changed the matrix, and false otherwise.

pub fn contains(&self, row: R, column: R) -> bool

Do the bits from row contain column? Put another way, is the matrix cell at (row, column) true? Put yet another way, if the matrix represents (transitive) reachability, can row reach column?

Important traits for Vec<u8>

impl Write for Vec<u8>

pub fn intersection(&self, a: R, b: R) -> Vec<C>

Returns those indices that are true in rows a and b. This is an O(n) operation where n is the number of elements (somewhat independent from the actual size of the intersection, in particular).

pub fn merge(&mut self, read: R, write: R) -> bool

Add the bits from row read to the bits from row write, return true if anything changed.

This is used when computing transitive reachability because if you have an edge write -> read, because in that case write can reach everything that read can (and potentially more).

Important traits for BitIter<'a, C>

impl<'a, C: Idx> Iterator for BitIter<'a, C> type Item = C;

pub fn iter<'a>(&'a self, row: R) -> BitIter<'a, C>

Iterates through all the columns set to true in a given row of the matrix.

Trait Implementations

impl<R: Clone + Idx, C: Clone + Idx> Clone for BitMatrix<R, C>

fn clone(&self) -> BitMatrix<R, C>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<R: Debug + Idx, C: Debug + Idx> Debug for BitMatrix<R, C>

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

Formats the value using the given formatter.