473 lines
12 KiB
JavaScript
473 lines
12 KiB
JavaScript
'use strict';
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//
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// list
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// ┌──────┐
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// ┌──────────────┼─head │
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// │ │ tail─┼──────────────┐
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// │ └──────┘ │
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// ▼ ▼
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// item item item item
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// ┌──────┐ ┌──────┐ ┌──────┐ ┌──────┐
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// null ◀──┼─prev │◀───┼─prev │◀───┼─prev │◀───┼─prev │
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// │ next─┼───▶│ next─┼───▶│ next─┼───▶│ next─┼──▶ null
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// ├──────┤ ├──────┤ ├──────┤ ├──────┤
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// │ data │ │ data │ │ data │ │ data │
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// └──────┘ └──────┘ └──────┘ └──────┘
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//
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let releasedCursors = null;
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class List {
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static createItem(data) {
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return {
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prev: null,
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next: null,
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data
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};
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}
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constructor() {
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this.head = null;
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this.tail = null;
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this.cursor = null;
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}
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createItem(data) {
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return List.createItem(data);
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}
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// cursor helpers
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allocateCursor(prev, next) {
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let cursor;
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if (releasedCursors !== null) {
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cursor = releasedCursors;
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releasedCursors = releasedCursors.cursor;
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cursor.prev = prev;
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cursor.next = next;
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cursor.cursor = this.cursor;
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} else {
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cursor = {
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prev,
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next,
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cursor: this.cursor
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};
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}
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this.cursor = cursor;
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return cursor;
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}
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releaseCursor() {
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const { cursor } = this;
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this.cursor = cursor.cursor;
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cursor.prev = null;
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cursor.next = null;
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cursor.cursor = releasedCursors;
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releasedCursors = cursor;
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}
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updateCursors(prevOld, prevNew, nextOld, nextNew) {
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let { cursor } = this;
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while (cursor !== null) {
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if (cursor.prev === prevOld) {
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cursor.prev = prevNew;
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}
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if (cursor.next === nextOld) {
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cursor.next = nextNew;
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}
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cursor = cursor.cursor;
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}
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}
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*[Symbol.iterator]() {
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for (let cursor = this.head; cursor !== null; cursor = cursor.next) {
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yield cursor.data;
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}
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}
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// getters
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get size() {
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let size = 0;
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for (let cursor = this.head; cursor !== null; cursor = cursor.next) {
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size++;
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}
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return size;
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}
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get isEmpty() {
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return this.head === null;
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}
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get first() {
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return this.head && this.head.data;
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}
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get last() {
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return this.tail && this.tail.data;
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}
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// convertors
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fromArray(array) {
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let cursor = null;
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this.head = null;
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for (let data of array) {
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const item = List.createItem(data);
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if (cursor !== null) {
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cursor.next = item;
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} else {
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this.head = item;
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}
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item.prev = cursor;
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cursor = item;
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}
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this.tail = cursor;
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return this;
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}
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toArray() {
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return [...this];
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}
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toJSON() {
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return [...this];
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}
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// array-like methods
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forEach(fn, thisArg = this) {
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// push cursor
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const cursor = this.allocateCursor(null, this.head);
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while (cursor.next !== null) {
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const item = cursor.next;
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cursor.next = item.next;
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fn.call(thisArg, item.data, item, this);
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}
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// pop cursor
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this.releaseCursor();
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}
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forEachRight(fn, thisArg = this) {
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// push cursor
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const cursor = this.allocateCursor(this.tail, null);
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while (cursor.prev !== null) {
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const item = cursor.prev;
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cursor.prev = item.prev;
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fn.call(thisArg, item.data, item, this);
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}
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// pop cursor
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this.releaseCursor();
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}
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reduce(fn, initialValue, thisArg = this) {
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// push cursor
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let cursor = this.allocateCursor(null, this.head);
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let acc = initialValue;
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let item;
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while (cursor.next !== null) {
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item = cursor.next;
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cursor.next = item.next;
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acc = fn.call(thisArg, acc, item.data, item, this);
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}
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// pop cursor
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this.releaseCursor();
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return acc;
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}
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reduceRight(fn, initialValue, thisArg = this) {
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// push cursor
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let cursor = this.allocateCursor(this.tail, null);
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let acc = initialValue;
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let item;
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while (cursor.prev !== null) {
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item = cursor.prev;
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cursor.prev = item.prev;
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acc = fn.call(thisArg, acc, item.data, item, this);
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}
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// pop cursor
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this.releaseCursor();
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return acc;
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}
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some(fn, thisArg = this) {
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for (let cursor = this.head; cursor !== null; cursor = cursor.next) {
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if (fn.call(thisArg, cursor.data, cursor, this)) {
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return true;
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}
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}
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return false;
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}
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map(fn, thisArg = this) {
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const result = new List();
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for (let cursor = this.head; cursor !== null; cursor = cursor.next) {
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result.appendData(fn.call(thisArg, cursor.data, cursor, this));
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}
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return result;
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}
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filter(fn, thisArg = this) {
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const result = new List();
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for (let cursor = this.head; cursor !== null; cursor = cursor.next) {
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if (fn.call(thisArg, cursor.data, cursor, this)) {
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result.appendData(cursor.data);
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}
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}
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return result;
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}
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nextUntil(start, fn, thisArg = this) {
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if (start === null) {
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return;
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}
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// push cursor
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const cursor = this.allocateCursor(null, start);
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while (cursor.next !== null) {
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const item = cursor.next;
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cursor.next = item.next;
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if (fn.call(thisArg, item.data, item, this)) {
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break;
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}
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}
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// pop cursor
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this.releaseCursor();
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}
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prevUntil(start, fn, thisArg = this) {
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if (start === null) {
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return;
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}
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// push cursor
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const cursor = this.allocateCursor(start, null);
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while (cursor.prev !== null) {
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const item = cursor.prev;
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cursor.prev = item.prev;
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if (fn.call(thisArg, item.data, item, this)) {
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break;
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}
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}
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// pop cursor
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this.releaseCursor();
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}
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// mutation
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clear() {
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this.head = null;
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this.tail = null;
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}
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copy() {
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const result = new List();
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for (let data of this) {
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result.appendData(data);
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}
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return result;
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}
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prepend(item) {
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// head
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// ^
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// item
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this.updateCursors(null, item, this.head, item);
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// insert to the beginning of the list
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if (this.head !== null) {
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// new item <- first item
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this.head.prev = item;
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// new item -> first item
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item.next = this.head;
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} else {
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// if list has no head, then it also has no tail
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// in this case tail points to the new item
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this.tail = item;
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}
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// head always points to new item
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this.head = item;
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return this;
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}
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prependData(data) {
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return this.prepend(List.createItem(data));
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}
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append(item) {
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return this.insert(item);
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}
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appendData(data) {
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return this.insert(List.createItem(data));
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}
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insert(item, before = null) {
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if (before !== null) {
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// prev before
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// ^
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// item
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this.updateCursors(before.prev, item, before, item);
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if (before.prev === null) {
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// insert to the beginning of list
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if (this.head !== before) {
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throw new Error('before doesn\'t belong to list');
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}
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// since head points to before therefore list doesn't empty
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// no need to check tail
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this.head = item;
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before.prev = item;
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item.next = before;
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this.updateCursors(null, item);
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} else {
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// insert between two items
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before.prev.next = item;
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item.prev = before.prev;
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before.prev = item;
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item.next = before;
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}
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} else {
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// tail
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// ^
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// item
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this.updateCursors(this.tail, item, null, item);
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// insert to the ending of the list
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if (this.tail !== null) {
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// last item -> new item
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this.tail.next = item;
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// last item <- new item
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item.prev = this.tail;
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} else {
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// if list has no tail, then it also has no head
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// in this case head points to new item
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this.head = item;
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}
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// tail always points to new item
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this.tail = item;
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}
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return this;
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}
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insertData(data, before) {
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return this.insert(List.createItem(data), before);
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}
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remove(item) {
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// item
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// ^
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// prev next
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this.updateCursors(item, item.prev, item, item.next);
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if (item.prev !== null) {
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item.prev.next = item.next;
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} else {
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if (this.head !== item) {
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throw new Error('item doesn\'t belong to list');
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}
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this.head = item.next;
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}
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if (item.next !== null) {
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item.next.prev = item.prev;
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} else {
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if (this.tail !== item) {
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throw new Error('item doesn\'t belong to list');
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}
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this.tail = item.prev;
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}
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item.prev = null;
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item.next = null;
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return item;
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}
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push(data) {
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this.insert(List.createItem(data));
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}
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pop() {
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return this.tail !== null ? this.remove(this.tail) : null;
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}
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unshift(data) {
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this.prepend(List.createItem(data));
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}
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shift() {
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return this.head !== null ? this.remove(this.head) : null;
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}
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prependList(list) {
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return this.insertList(list, this.head);
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}
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appendList(list) {
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return this.insertList(list);
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}
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insertList(list, before) {
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// ignore empty lists
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if (list.head === null) {
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return this;
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}
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if (before !== undefined && before !== null) {
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this.updateCursors(before.prev, list.tail, before, list.head);
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// insert in the middle of dist list
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if (before.prev !== null) {
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// before.prev <-> list.head
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before.prev.next = list.head;
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list.head.prev = before.prev;
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} else {
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this.head = list.head;
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}
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before.prev = list.tail;
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list.tail.next = before;
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} else {
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this.updateCursors(this.tail, list.tail, null, list.head);
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// insert to end of the list
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if (this.tail !== null) {
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// if destination list has a tail, then it also has a head,
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// but head doesn't change
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// dest tail -> source head
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this.tail.next = list.head;
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// dest tail <- source head
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list.head.prev = this.tail;
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} else {
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// if list has no a tail, then it also has no a head
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// in this case points head to new item
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this.head = list.head;
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}
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// tail always start point to new item
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this.tail = list.tail;
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}
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list.head = null;
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list.tail = null;
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return this;
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}
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replace(oldItem, newItemOrList) {
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if ('head' in newItemOrList) {
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this.insertList(newItemOrList, oldItem);
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} else {
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this.insert(newItemOrList, oldItem);
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}
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this.remove(oldItem);
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}
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}
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exports.List = List;
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