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#![allow(dead_code)]
use conjure_cp::ast::eval::vec_op;
use conjure_cp::ast::{
Atom, Expression as Expr, Metadata, SymbolTable, eval_constant, run_partial_evaluator,
};
use conjure_cp::rule_engine::{
ApplicationError::RuleNotApplicable, ApplicationResult, Reduction, register_rule,
register_rule_set,
use std::sync::Arc;
use std::sync::atomic::{AtomicBool, Ordering};
use uniplate::Biplate;
register_rule_set!("Constant", ());
#[register_rule(("Base",9000))]
fn partial_evaluator(expr: &Expr, _: &SymbolTable) -> ApplicationResult {
run_partial_evaluator(expr)
}
#[register_rule(("Constant", 9001))]
fn constant_evaluator(expr: &Expr, _: &SymbolTable) -> ApplicationResult {
// I break the rules a bit here: this is a global rule!
//
// This rule is really really hot when expanding comprehensions.. Also, at time of writing, we
// have the naive rewriter, which is slow on large trees....
// Also, constant_evaluating bottom up vs top down does things in less passes: the rewriter,
// however, favour doing this top-down!
// e.g. or([(1=1),(2=2),(3+3 = 6)])
if !matches!(expr, Expr::Root(_, _)) {
return Err(RuleNotApplicable);
let has_changed: Arc<AtomicBool> = Arc::new(AtomicBool::new(false));
let has_changed_2 = Arc::clone(&has_changed);
let new_expr = expr.transform_bi(&move |x| {
if let Expr::Atomic(_, Atom::Literal(_)) = x {
return x;
match eval_constant(&x)
.map(|c| Expr::Atomic(Metadata::new(), Atom::Literal(c)))
.or_else(|| run_partial_evaluator(&x).ok().map(|r| r.new_expression))
{
Some(new_expr) => {
has_changed.store(true, Ordering::Relaxed);
new_expr
None => x,
});
if has_changed_2.load(Ordering::Relaxed) {
Ok(Reduction::pure(new_expr))
} else {
Err(RuleNotApplicable)
/// Evaluate the root expression.
///
/// This returns either Expr::Root([true]) or Expr::Root([false]).
fn eval_root(expr: &Expr, _: &SymbolTable) -> ApplicationResult {
// this is its own rule not part of apply_eval_constant, because root should return a new root
// with a literal inside it, not just a literal
let Expr::Root(_, exprs) = expr else {
match exprs.len() {
0 => Ok(Reduction::pure(Expr::Root(
Metadata::new(),
vec![true.into()],
))),
1 => Err(RuleNotApplicable),
_ => {
let lit =
vec_op::<bool, bool>(|e| e.iter().all(|&e| e), exprs).ok_or(RuleNotApplicable)?;
Ok(Reduction::pure(Expr::Root(
vec![lit.into()],
)))
#[cfg(test)]
mod tests {
use conjure_cp::ast::{Expression, Moo, eval_constant};
use conjure_cp::essence_expr;
#[test]
fn div_by_zero() {
let expr = essence_expr!(1 / 0);
assert_eq!(eval_constant(&expr), None);
fn safediv_by_zero() {
let expr = Expression::SafeDiv(
Default::default(),
Moo::new(essence_expr!(1)),
Moo::new(essence_expr!(0)),
);