Lines
0 %
Functions
use conjure_core::ast::{Expression, ReturnType};
use conjure_core::metadata::Metadata;
use conjure_core::rule_engine::{
register_rule, register_rule_set, ApplicationError, ApplicationResult, Reduction,
};
use conjure_core::Model;
use uniplate::Uniplate;
register_rule_set!("Bubble", 254, ("Base"));
// Bubble reduction rules
/*
Reduce bubbles with a boolean expression to a conjunction with their condition.
e.g. (a / b = c) @ (b != 0) => (a / b = c) & (b != 0)
*/
#[register_rule(("Bubble", 100))]
fn expand_bubble(expr: &Expression, _: &Model) -> ApplicationResult {
match expr {
Expression::Bubble(_, a, b) if a.return_type() == Some(ReturnType::Bool) => {
Ok(Reduction::pure(Expression::And(
Metadata::new(),
vec![*a.clone(), *b.clone()],
)))
}
_ => Err(ApplicationError::RuleNotApplicable),
Bring bubbles with a non-boolean expression higher up the tree.
E.g. ((a / b) @ (b != 0)) = c => (a / b = c) @ (b != 0)
fn bubble_up(expr: &Expression, _: &Model) -> ApplicationResult {
let mut sub = expr.children();
let mut bubbled_conditions = vec![];
for e in sub.iter_mut() {
if let Expression::Bubble(_, a, b) = e {
if a.return_type() != Some(ReturnType::Bool) {
bubbled_conditions.push(*b.clone());
*e = *a.clone();
if bubbled_conditions.is_empty() {
return Err(ApplicationError::RuleNotApplicable);
return Ok(Reduction::pure(Expression::Bubble(
Box::new(expr.with_children(sub)),
Box::new(Expression::And(Metadata::new(), bubbled_conditions)),
)));
// Bubble applications
Convert an unsafe division to a safe division with a bubble condition.
Division by zero is undefined and therefore not allowed, so we add a condition to check for it.
This condition is brought up the tree and expanded into a conjunction with the first boolean-type expression it is paired with.
E.g. a / b => (a / b) @ (b != 0)
fn div_to_bubble(expr: &Expression, _: &Model) -> ApplicationResult {
if let Expression::UnsafeDiv(_, a, b) = expr {
Box::new(Expression::SafeDiv(Metadata::new(), a.clone(), b.clone())),
Box::new(Expression::Neq(
b.clone(),
Box::new(Expression::from(0)),
)),