✨ feat: Implement values and _iter_fast.

Fixes #45 and fixes #46.

Author: make-github-pseudonymous-again

src/_iter_fast.js

@@ -0,0 +1,23 @@
+import assert from 'assert';
+import Node from './Node.js';
+
+/**
+ * Generator of nodes in list in order. The list cannot be empty. You should
+ * not modify the current node's next pointer unless you know what you are
+ * doing.
+ *
+ * /!\ Modifying the next pointer of the current node will change which node
+ * comes next in the iteration.
+ *
+ * @param {Node} first First node of the list.
+ * @return {IterableIterator<Node>} Yields nodes of a list in order.
+ */
+export default function* _iter_fast(first) {
+	assert(first instanceof Node);
+	let next = first;
+
+	do {
+		yield next;
+		next = next.next;
+	} while (next !== first);
+}

src/index.js

@@ -2,6 +2,7 @@ export {default as Node} from './Node.js';
 export {default as _append} from './_append.js';
 export {default as _concat} from './_concat.js';
 export {default as _iter} from './_iter.js';
+export {default as _iter_fast} from './_iter_fast.js';
 export {default as _len} from './_len.js';
 export {default as _remove} from './_remove.js';
 export {default as concat} from './concat.js';
@@ -13,3 +14,4 @@ export {default as pop} from './pop.js';
 export {default as push} from './push.js';
 export {default as shift} from './shift.js';
 export {default as unshift} from './unshift.js';
+export {default as values} from './values.js';

src/values.js

@@ -0,0 +1,16 @@
+import assert from 'assert';
+import _iter_fast from './_iter_fast.js';
+import Node from './Node.js';
+
+/**
+ * Generator of nodes in list in order.
+ *
+ * @param {Node} first First node of the list (can be null).
+ * @return {IterableIterator<any>}
+ */
+export default function* values(first) {
+	assert(first === null || first instanceof Node);
+	if (first !== null) {
+		for (const x of _iter_fast(first)) yield x.value;
+	}
+}

test/src/api.js

@@ -1,6 +1,6 @@
 import test from 'ava';
 
-import {list, map} from '@aureooms/js-itertools';
+import {list} from '@aureooms/js-itertools';
 
 import {
 	empty,
@@ -10,51 +10,51 @@ import {
 	shift,
 	unshift,
 	concat,
-	iter,
+	values,
 } from '../../src/index.js';
 
-const values = (first) => list(map((x) => x.value, iter(first)));
+const toArray = (first) => list(values(first));
 
 test('API', (t) => {
 	let A = empty();
 
-	t.deepEqual(values(A), []);
+	t.deepEqual(toArray(A), []);
 
 	t.throws(() => pop(A), {message: /empty/});
 	t.throws(() => shift(A), {message: /empty/});
 
 	A = push(A, 1);
 
-	t.deepEqual(values(A), [1]);
+	t.deepEqual(toArray(A), [1]);
 
 	A = unshift(A, 2);
 
-	t.deepEqual(values(A), [2, 1]);
+	t.deepEqual(toArray(A), [2, 1]);
 
 	let B = from([4, 3]);
 
-	t.deepEqual(values(B), [4, 3]);
+	t.deepEqual(toArray(B), [4, 3]);
 
 	B = concat(A, B);
 	A = empty();
 
-	t.deepEqual(values(B), [2, 1, 4, 3]);
-	t.deepEqual(values(A), []);
+	t.deepEqual(toArray(B), [2, 1, 4, 3]);
+	t.deepEqual(toArray(A), []);
 
 	B = concat(A, B);
-	t.deepEqual(values(B), [2, 1, 4, 3]);
+	t.deepEqual(toArray(B), [2, 1, 4, 3]);
 
 	B = concat(B, A);
-	t.deepEqual(values(B), [2, 1, 4, 3]);
+	t.deepEqual(toArray(B), [2, 1, 4, 3]);
 
 	A = unshift(A, 8);
-	t.deepEqual(values(A), [8]);
+	t.deepEqual(toArray(A), [8]);
 	B = push(B, 7);
-	t.deepEqual(values(B), [2, 1, 4, 3, 7]);
+	t.deepEqual(toArray(B), [2, 1, 4, 3, 7]);
 
 	A = concat(A, B);
 	B = empty();
 
-	t.deepEqual(values(A), [8, 2, 1, 4, 3, 7]);
-	t.deepEqual(values(B), []);
+	t.deepEqual(toArray(A), [8, 2, 1, 4, 3, 7]);
+	t.deepEqual(toArray(B), []);
 });