🚧 progress: First draft.

Author: make-github-pseudonymous-again

doc/scripts/header.js

@@ -17,7 +17,8 @@ domReady(() => {
 	header.insertBefore(projectname, header.firstChild);
 
 	const testlink = document.querySelector('header > a[data-ice="testLink"]');
-	testlink.href = 'https://app.codecov.io/gh/data-structure-algebra/singly-linked-list';
+	testlink.href =
+		'https://app.codecov.io/gh/data-structure-algebra/singly-linked-list';
 	testlink.target = '_BLANK';
 
 	const searchBox = document.querySelector('.search-box');

package.json

@@ -65,6 +65,9 @@
     "@babel/preset-env": "7.15.0",
     "@babel/register": "7.14.5",
     "@commitlint/cli": "13.1.0",
+    "@iterable-iterator/list": "^1.0.1",
+    "@iterable-iterator/map": "^1.0.1",
+    "@iterable-iterator/range": "^2.1.0",
     "@js-library/commitlint-config": "0.0.4",
     "ava": "3.15.0",
     "babel-plugin-transform-remove-console": "6.9.4",
@@ -197,15 +200,9 @@
       "unicorn"
     ],
     "rules": {
-      "unicorn/filename-case": [
-        "error",
-        {
-          "cases": {
-            "camelCase": true,
-            "pascalCase": true
-          }
-        }
-      ],
+      "camelcase": "off",
+      "unicorn/prevent-abbreviations": "off",
+      "unicorn/filename-case": "off",
       "unicorn/prefer-node-protocol": "off"
     },
     "overrides": [

src/Node.js

@@ -0,0 +1,9 @@
+/**
+ * Node.
+ *
+ * @param {any} value
+ */
+export default function Node(value) {
+	this._value = value;
+	this._next = null;
+}

src/_isLast.js

@@ -0,0 +1,18 @@
+import assert from 'assert';
+
+// eslint-disable-next-line no-unused-vars
+import Node from './Node.js';
+import isEmpty from './isEmpty.js';
+import isNonEmpty from './isNonEmpty.js';
+import _shift from './_shift.js';
+
+/**
+ * _isLast.
+ *
+ * @param {Node} x
+ * @return {boolean}
+ */
+export default function _isLast(x) {
+	assert(isNonEmpty(x));
+	return isEmpty(_shift(x));
+}

src/_iter.js

@@ -0,0 +1,28 @@
+import assert from 'assert';
+
+// eslint-disable-next-line no-unused-vars
+import Node from './Node.js';
+import _shift from './_shift.js';
+import isEmpty from './isEmpty.js';
+import isNonEmpty from './isNonEmpty.js';
+
+/**
+ * Generator of nodes in list in order. You are allowed to edit the current
+ * node.
+ *
+ * /!\ Modifying the next pointer of the current node will NOT 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(first) {
+	assert(isNonEmpty(first));
+	let next = first;
+
+	do {
+		const x = next;
+		next = _shift(x); // Compute next before yielding.
+		yield x; // Necessary ?
+	} while (!isEmpty(next));
+}

src/_iter_fast.js

@@ -0,0 +1,28 @@
+import assert from 'assert';
+
+// eslint-disable-next-line no-unused-vars
+import Node from './Node.js';
+import isEmpty from './isEmpty.js';
+import isNonEmpty from './isNonEmpty.js';
+import _shift from './_shift.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(isNonEmpty(first));
+	let next = first;
+
+	do {
+		yield next;
+		next = _shift(next);
+	} while (!isEmpty(next));
+}

src/_last.js

@@ -0,0 +1,22 @@
+import assert from 'assert';
+
+// eslint-disable-next-line no-unused-vars
+import Node from './Node.js';
+import isNonEmpty from './isNonEmpty.js';
+import _isLast from './_isLast.js';
+import _shift from './_shift.js';
+
+/**
+ * Return the last node of a non-empty input list.
+ *
+ * @param {Node} x First node of the input list.
+ * @return {Node} Last node of the input list.
+ */
+export default function _last(x) {
+	assert(isNonEmpty(x));
+	while (!_isLast(x)) {
+		x = _shift(x);
+	}
+
+	return x;
+}

src/_len.js

@@ -0,0 +1,25 @@
+import assert from 'assert';
+
+// eslint-disable-next-line no-unused-vars
+import Node from './Node.js';
+import isEmpty from './isEmpty.js';
+import isNonEmpty from './isNonEmpty.js';
+import _shift from './_shift.js';
+
+/**
+ * Compute the length of a non-empty list.
+ *
+ * @param {Node} x First node of the input list.
+ * @return {number} The length of the input list.
+ */
+export default function _len(x) {
+	assert(isNonEmpty(x));
+	let n = 1;
+	let y = _shift(x);
+	while (!isEmpty(y)) {
+		++n;
+		y = _shift(y);
+	}
+
+	return n;
+}

src/_pop.js

@@ -0,0 +1,29 @@
+import assert from 'assert';
+
+// eslint-disable-next-line no-unused-vars
+import Node from './Node.js';
+import empty from './empty.js';
+import isNonEmpty from './isNonEmpty.js';
+import _isLast from './_isLast.js';
+import _setNext from './_setNext.js';
+import _shift from './_shift.js';
+
+/**
+ * Removes last {@link Node} from a non-empty list.
+ *
+ * @param {Node} x First node of input list (non-empty).
+ * @return {[Node, Node]} New list (possibly empty) and removed node.
+ */
+export default function _pop(x) {
+	assert(isNonEmpty(x));
+	if (_isLast(x)) return [empty(), x];
+	let penultimate = x;
+	let last = _shift(x);
+	while (!_isLast(last)) {
+		penultimate = last;
+		last = _shift(last);
+	}
+
+	_setNext(penultimate, empty());
+	return [x, last];
+}

src/_setNext.js

@@ -0,0 +1,18 @@
+import assert from 'assert';
+
+// eslint-disable-next-line no-unused-vars
+import Node from './Node.js';
+import isList from './isList.js';
+import isNonEmpty from './isNonEmpty.js';
+
+/**
+ * Replace successor of the input node.
+ *
+ * @param {Node} x Node to replace the sucessor of.
+ * @param {Node} y New successor (possibly null).
+ */
+export default function _setNext(x, y) {
+	assert(isNonEmpty(x));
+	assert(isList(y));
+	x._next = y;
+}

src/_setValue.js

@@ -0,0 +1,16 @@
+import assert from 'assert';
+
+// eslint-disable-next-line no-unused-vars
+import Node from './Node.js';
+import isNonEmpty from './isNonEmpty.js';
+
+/**
+ * Set value held by input node.
+ *
+ * @param {Node} x Input node (cannot be null).
+ * @param {any} value
+ */
+export default function _setValue(x, value) {
+	assert(isNonEmpty(x));
+	x._value = value;
+}

src/_shift.js

@@ -0,0 +1,16 @@
+import assert from 'assert';
+
+// eslint-disable-next-line no-unused-vars
+import Node from './Node.js';
+import isNonEmpty from './isNonEmpty.js';
+
+/**
+ * Removes first {@link Node} from a non-empty list.
+ *
+ * @param {Node} x First node (not null).
+ * @return {Node} New list (possibly empty).
+ */
+export default function _shift(x) {
+	assert(isNonEmpty(x));
+	return x._next;
+}

src/_value.js

@@ -0,0 +1,16 @@
+import assert from 'assert';
+
+// eslint-disable-next-line no-unused-vars
+import Node from './Node.js';
+import isNonEmpty from './isNonEmpty.js';
+
+/**
+ * Return the first value held by a non-empty list.
+ *
+ * @param {Node} x First node.
+ * @return {any}
+ */
+export default function value(x) {
+	assert(isNonEmpty(x));
+	return x._value;
+}

src/concat.js

@@ -0,0 +1,24 @@
+import assert from 'assert';
+
+// eslint-disable-next-line no-unused-vars
+import Node from './Node.js';
+import isEmpty from './isEmpty.js';
+import isNonEmpty from './isNonEmpty.js';
+import _setNext from './_setNext.js';
+import _last from './_last.js';
+
+/**
+ * Concatenate two input lists.
+ *
+ * @param {Node} x First node of first input list (can empty).
+ * @param {Node} y First node of second input list (can empty).
+ * @return {Node} First node of the output list (or an empty list).
+ */
+export default function concat(x, y) {
+	if (isEmpty(x)) return y;
+	assert(isNonEmpty(x));
+	if (isEmpty(y)) return x;
+	assert(isNonEmpty(y));
+	_setNext(_last(x), y);
+	return x;
+}

src/empty.js

@@ -0,0 +1,8 @@
+/**
+ * Return an empty list.
+ *
+ * @return {null} The empty list.
+ */
+export default function empty() {
+	return null;
+}

src/from.js

@@ -0,0 +1,29 @@
+// eslint-disable-next-line no-unused-vars
+import Node from './Node.js';
+import _setNext from './_setNext.js';
+import empty from './empty.js';
+import single from './single.js';
+
+/**
+ * Creates a list from an input iterable.
+ *
+ * @param {IterableIterator} iterable The input iterable.
+ * @return {Node} First node of the newly created list (or null if empty list).
+ */
+export default function from(iterable) {
+	const it = iterable[Symbol.iterator]();
+	const event = it.next();
+
+	if (event.done) return empty();
+
+	const first = single(event.value);
+	let last = first;
+
+	for (const value of it) {
+		const next = single(value);
+		_setNext(last, next);
+		last = next;
+	}
+
+	return first;
+}

src/index.js

@@ -1,2 +1,29 @@
-const answer = 42;
-export default answer;
+export {default as Node} from './Node.js';
+export {default as _isLast} from './_isLast.js';
+export {default as _iter} from './_iter.js';
+export {default as _iter_fast} from './_iter_fast.js';
+export {default as _last} from './_last.js';
+export {default as _len} from './_len.js';
+export {default as _pop} from './_pop.js';
+export {default as _setNext} from './_setNext.js';
+export {default as _setValue} from './_setValue.js';
+export {default as _shift} from './_shift.js';
+export {default as _value} from './_value.js';
+export {default as concat} from './concat.js';
+export {default as empty} from './empty.js';
+export {default as from} from './from.js';
+export {default as isEmpty} from './isEmpty.js';
+export {default as isLast} from './isLast.js';
+export {default as isList} from './isList.js';
+export {default as isNonEmpty} from './isNonEmpty.js';
+export {default as iter} from './iter.js';
+export {default as last} from './last.js';
+export {default as len} from './len.js';
+export {default as pop} from './pop.js';
+export {default as push} from './push.js';
+export {default as setValue} from './setValue.js';
+export {default as shift} from './shift.js';
+export {default as single} from './single.js';
+export {default as unshift} from './unshift.js';
+export {default as value} from './value.js';
+export {default as values} from './values.js';

src/isEmpty.js

@@ -0,0 +1,11 @@
+import empty from './empty.js';
+
+/**
+ * Return whether the input is a list and is empty.
+ *
+ * @param {any} x Input.
+ * @return {boolean} True iff the input is an empty list.
+ */
+export default function isEmpty(x) {
+	return x === empty();
+}