✨ feat: Add reverse.

Author: make-github-pseudonymous-again

README.md

@@ -4,12 +4,16 @@
 ArrayLike reversing for JavaScript.
 See [docs](https://array-like.github.io/reverse/index.html).
 
-> :building_construction: Caveat emptor! This is work in progress. Code may be
-> working. Documentation may be present. Coherence may be. Maybe.
+```js
+import {reverse} from '@array-like/reverse';
 
-> :warning: Depending on your environment, the code may require
-> `regeneratorRuntime` to be defined, for instance by importing
-> [regenerator-runtime/runtime](https://www.npmjs.com/package/regenerator-runtime).
+const a = Int32Array.from([1, 2, 3]);
+a; 1 2 3
+reverse(a, 0, 3);
+a; 3 2 1
+reverse(a, 1, 3);
+a; 3 1 2
+```
 
 [![License](https://img.shields.io/github/license/array-like/reverse.svg)](https://raw.githubusercontent.com/array-like/reverse/main/LICENSE)
 [![Version](https://img.shields.io/npm/v/@array-like/reverse.svg)](https://www.npmjs.org/package/@array-like/reverse)

doc/manual/usage.md

@@ -1,19 +1,8 @@
 # Usage
 
-> :warning: Depending on your environment, the code may require
-> `regeneratorRuntime` to be defined, for instance by importing
-> [regenerator-runtime/runtime](https://www.npmjs.com/package/regenerator-runtime).
-
-First, require the polyfill at the entry point of your application
-```js
-await import('regenerator-runtime/runtime.js');
-// or
-import 'regenerator-runtime/runtime.js';
-```
-
-Then, import the library where needed
+Import the library where needed
 ```js
-const reverse = await import('@array-like/reverse');
+const {reverse} = await import('@array-like/reverse');
 // or
-import * as reverse from '@array-like/reverse';
+import {reverse} from '@array-like/reverse';
 ```

package.json

@@ -59,8 +59,12 @@
     "release": "np --message ':hatching_chick: release: Bumping to v%s.'",
     "test": "ava"
   },
-  "dependencies": {},
+  "dependencies": {
+    "@array-like/swap": "^0.0.1"
+  },
   "devDependencies": {
+    "@array-like/alloc": "^0.0.1",
+    "@array-like/copy": "^0.0.1",
     "@babel/core": "7.14.8",
     "@babel/preset-env": "7.14.8",
     "@babel/register": "7.14.5",

src/index.js

@@ -1,2 +1 @@
-const answer = 42;
-export default answer;
+export {default as reverse} from './reverse.js';

src/reverse.js

@@ -0,0 +1,14 @@
+import {swap} from '@array-like/swap';
+
+/**
+ * Reverse.
+ *
+ * @param {{[x:number]: any}} a
+ * @param {number} i
+ * @param {number} j
+ */
+const reverse = (a, i, j) => {
+	while (i < j) swap(a, i++, --j);
+};
+
+export default reverse;

test/src/api.js

@@ -0,0 +1,50 @@
+import test from 'ava';
+
+import {alloc} from '@array-like/alloc';
+import {copy} from '@array-like/copy';
+
+import {reverse} from '../../src/index.js';
+
+const macro = (t, a, i, j, expected) => {
+	const reference = alloc(a.length);
+	copy(a, 0, a.length, reference, 0);
+
+	reverse(a, i, j);
+	t.deepEqual(a, expected, 'reverse x 1');
+
+	reverse(a, i, j);
+	t.deepEqual(a, reference, 'reverse x 2');
+};
+
+const repr = JSON.stringify;
+
+macro.title = (title, a, i, j, expected) =>
+	title ?? `reverse(${repr(a)}, ${i}, ${j}) is ${repr(expected)}`;
+
+const immutable = (t, a, i, j) => macro(t, a, i, j, a.slice());
+immutable.title = (title, a, i, j) => macro.title(title, a, i, j, a.slice());
+
+const whole = (t, a, expected) => macro(t, a, 0, a.length, expected);
+whole.title = (title, a, expected) =>
+	macro.title(title, a, 0, a.length, expected);
+
+test(immutable, [1, 2, 3, 4, 5, 6, 7, 8, 9], 4, 4);
+test(immutable, [1, 2, 3, 4, 5, 6, 7, 8, 9], 5, 5);
+test(immutable, [1, 2, 3, 4, 5, 6, 7, 8, 9], 2, 1);
+test(immutable, [1, 2, 3, 4, 5, 6, 7, 8, 9], 0, -1);
+test(immutable, [1, 2, 3, 4, 5, 6, 7, 8, 9], 1, 0);
+test(immutable, [1, 2, 3, 4, 5, 6, 7, 8, 9], 9, 0);
+test(immutable, [1, 2, 3, 4, 5, 6, 7, 8, 9], 27, -32);
+
+test(whole, [], []);
+test(whole, [1], [1]);
+test(whole, [1, 2, 3], [3, 2, 1]);
+test(whole, [1, 2, 3, 4, 5, 6], [6, 5, 4, 3, 2, 1]);
+test(whole, [1, 2, 3, 4, 5, 6, 7, 8, 9], [9, 8, 7, 6, 5, 4, 3, 2, 1]);
+
+test(macro, [1, 2, 3, 4, 5, 6, 7, 8, 9], 3, 7, [1, 2, 3, 7, 6, 5, 4, 8, 9]);
+test(macro, [1, 2, 3, 4, 5, 6, 7, 8, 9], 3, 8, [1, 2, 3, 8, 7, 6, 5, 4, 9]);
+test(macro, [1, 2, 3, 4, 5, 6, 7, 8, 9], 3, 9, [1, 2, 3, 9, 8, 7, 6, 5, 4]);
+test(macro, [1, 2, 3, 4, 5, 6, 7, 8, 9], 0, 6, [6, 5, 4, 3, 2, 1, 7, 8, 9]);
+test(macro, [1, 2, 3, 4, 5, 6, 7, 8, 9], 0, 5, [5, 4, 3, 2, 1, 6, 7, 8, 9]);
+test(macro, [1, 2, 3, 4, 5, 6, 7, 8, 9], 0, 4, [4, 3, 2, 1, 5, 6, 7, 8, 9]);