Struct Substitution 

pub struct Substitution { /* private fields */ }

A substitution mapping: a list of (FVarId, Expr) pairs.

Used to represent simultaneous substitution of free variables.

Implementations

impl Substitution

pub fn new() -> Self

Create an empty substitution.

pub fn insert(&mut self, fvar: FVarId, expr: Expr)

Add a mapping fvar → expr to the substitution.

pub fn get(&self, fvar: FVarId) -> Option<&Expr>

Look up the image of a free variable.

pub fn len(&self) -> usize

Number of mappings.

pub fn is_empty(&self) -> bool

Check if empty.

pub fn apply(&self, expr: &Expr) -> Expr

Apply this substitution to an expression.

Replaces each FVar(id) found in expr with the corresponding image.

pub fn compose(&self, other: &Substitution) -> Substitution

Compose self with other: apply other to all images in self, then merge. Maps in self override other for the same variable.

pub fn remove(&mut self, fvar: FVarId)

Remove a mapping.

pub fn restrict(&self, keep: &[FVarId]) -> Substitution

Restrict the substitution to only those fvars in keep.

Trait Implementations

impl Clone for Substitution

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Substitution

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

Formats the value using the given formatter.

impl Default for Substitution

fn default() -> Self

Returns the “default value” for a type.