Trait Columns 

pub trait Columns: Sized {
    // Required methods
    fn column(c: usize) -> Self;
    fn is_column(&self) -> bool;
    fn as_column(&self) -> Option<usize>;
    fn as_column_mut(&mut self) -> Option<&mut usize>;
    fn support_into(&self, support: &mut BTreeSet<usize>);
    fn visit_columns<F>(&mut self, action: F)
       where F: FnMut(&mut usize);

    // Provided methods
    fn support(&self) -> BTreeSet<usize> { ... }
    fn permute(&mut self, permutation: &[usize]) { ... }
    fn permute_map(&mut self, permutation: &BTreeMap<usize, usize>) { ... }
}

Required Methods

fn column(c: usize) -> Self

Construct a column reference expression.

fn is_column(&self) -> bool

True when the outermost structure is a column.

fn as_column(&self) -> Option<usize>

If self is a column, return the column index, otherwise None.

fn as_column_mut(&mut self) -> Option<&mut usize>

If self is a column, return a mutable reference to the column index.

fn support_into(&self, support: &mut BTreeSet<usize>)

Adds the support of the given set, i.e., the columns that are actually used, to the given set.

fn visit_columns<F>(&mut self, action: F)

where F: FnMut(&mut usize),

Visits each column reference and applies action to the column.

Useful for remapping columns, or for collecting expression support.

Provided Methods

fn support(&self) -> BTreeSet<usize>

The support of the given set, i.e., the columns that are actually used.

You can use BTreeSet::last() to extract the maximum column.

fn permute(&mut self, permutation: &[usize])

Rewrites column indices with their value in permutation.

This method is applicable even when permutation is not a strict permutation, and it only needs to have entries for each column referenced in self.

fn permute_map(&mut self, permutation: &BTreeMap<usize, usize>)

Rewrites column indices with their value in permutation.

This method is applicable even when permutation is not a strict permutation, and it only needs to have entries for each column referenced in self.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl Columns for MirScalarExpr