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Functions
50 %
use conjure_cp::rule_engine::SubmodelZipper;
use conjure_cp::{
ast::{Expression, SymbolTable},
rule_engine::{ApplicationError::RuleNotApplicable, ApplicationResult, Reduction},
};
/// Converts the rule function `rule` to a rule that applies `rule` bottom-up to every expression
/// in the current sub-model.
pub fn as_bottom_up(
rule: impl Fn(&Expression, &SymbolTable) -> ApplicationResult,
) -> impl Fn(&Expression, &SymbolTable) -> ApplicationResult {
Box::new(move |expr: &Expression, symbols: &SymbolTable| {
// global rule
if !matches!(expr, Expression::Root(_, _)) {
return Err(RuleNotApplicable);
// traverse bottom up within the current sub-model, applying the rule.
let mut symbols = symbols.clone();
let mut new_tops = vec![];
let mut done_something = false;
let mut zipper = SubmodelZipper::new(expr.clone());
while zipper.go_down().is_some() {}
loop {
// go right and to the bottom of that subtree
//
// once we have ran out of siblings, go_up.
if zipper.go_right().is_some() {
} else if zipper.go_up().is_none() {
// cannot go up anymore, at the root
break;
}
let expr = zipper.focus();
if let Ok(mut reduction) = rule(expr, &symbols) {
zipper.replace_focus(reduction.new_expression);
symbols.extend(reduction.symbols);
new_tops.append(&mut reduction.new_top);
done_something = true;
let root_expr = zipper.rebuild_root();
if done_something {
Ok(Reduction::new(root_expr, new_tops, symbols))
} else {
Err(RuleNotApplicable)
})