src/sjs.mjs: Loop for reduce to avoid stack overflowsHEADmain

2 files changed, 9 insertions, 59 deletions

diff --git a/src/sjs.mjs b/src/sjs.mjs
index aae85a7..aafd7ba 100644
--- a/src/sjs.mjs
+++ b/src/sjs.mjs
@@ -292,20 +292,16 @@ export const isReduced = x => x instanceof Reduced;
 
 export const reduced = x => new Reduced(x);
 
-const reduceRec = (coll, fn, acc, index) =>
-	isReduced(acc) ? acc.value :
-		index === coll.length ? acc :
-			reduceRec(
-				coll,
-				fn,
-				fn(acc, coll[index], index, coll),
-				index + 1,
-			);
+export const reduce = (coll, fn, init) => {
+	let acc   = init === undefined ? coll[0] : init;
+	let start = init === undefined ? 1       : 0;
+	for (let i = start; i < coll.length; i++) {
+		acc = fn(acc, coll[i], i, coll);
+		if (isReduced(acc)) return acc.value;
+	}
+	return acc;
+};
 
-export const reduce = (coll, fn, init) =>
-	init === undefined
-		? reduceRec(coll.slice(1), fn, coll[0], 0)
-		: reduceRec(coll,          fn, init,    0);
 
 const reductionsRec = (coll, fn, acc, index, steps) => {
 	if (isReduced(acc)) {
diff --git a/tests/sjs.mjs b/tests/sjs.mjs
index 9376429..01871ae 100644
--- a/tests/sjs.mjs
+++ b/tests/sjs.mjs
@@ -30,7 +30,6 @@ import {
 	makeRandom,
 	isReduced,
 	reduced,
-	reduceRec,
 	reduce,
 	reductionsRec,
 	reductions,
@@ -897,50 +896,6 @@ const test_reduced = t => {
 	});
 };
 
-const test_reduceRec = t => {
-	t.start("reduceRec()");
-
-	t.testing("return the value if isReduced()", () => {
-		t.assertEq(reduceRec(null, null, reduced("abc"), null), "abc");
-	});
-
-	t.testing("the bare value if at the end of the collection", () => {
-		t.assertEq(reduceRec([], null, "acc", 0), "acc");
-		t.assertEq(reduceRec([1, 2], null, "acc", 2), "acc");
-	});
-
-	t.testing("recurse while applying function", () => {
-		const expected = [{
-			acc:   -5,
-			el:    4,
-			index: 3,
-			coll:  [1, 2, 3, 4, 5],
-			ret:   -1,
-		}, {
-			acc:   -1,
-			el:    5,
-			index: 4,
-			coll:  [1, 2, 3, 4, 5],
-			ret:   4,
-		}];
-		const calls = [];
-		const fn = (acc, el, index, coll) => {
-			const ret = acc + el;
-			calls.push({
-				acc,
-				el,
-				index,
-				coll,
-				ret,
-			});
-			return ret;
-		};
-		const coll = [1, 2, 3, 4, 5];
-		t.assertEq(reduceRec(coll, fn, -5, 3), 4);
-		t.assertEq(calls, expected);
-	});
-};
-
 const test_reduce = t => {
 	t.start("reduce()");
 
@@ -1087,7 +1042,6 @@ runTests([
 	test_makeRandom,
 	test_isReduced,
 	test_reduced,
-	test_reduceRec,
 	test_reduce,
 	test_reductionsRec,
 	test_reductions,