Code
107 lines
2.4 KiB
TypeScript
107 lines
2.4 KiB
TypeScript
/*---------------------------------------------------------------------------------------------
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* Copyright (c) Microsoft Corporation. All rights reserved.
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* Licensed under the MIT License. See License.txt in the project root for license information.
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*--------------------------------------------------------------------------------------------*/
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'use strict';
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export interface IIterator<T> {
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next(): T;
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}
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export class ArrayIterator<T> implements IIterator<T> {
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private items: T[];
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protected start: number;
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protected end: number;
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protected index: number;
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constructor(items: T[], start: number = 0, end: number = items.length) {
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this.items = items;
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this.start = start;
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this.end = end;
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this.index = start - 1;
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}
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public first(): T {
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this.index = this.start;
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return this.current();
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}
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public next(): T {
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this.index = Math.min(this.index + 1, this.end);
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return this.current();
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}
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protected current(): T {
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if (this.index === this.start - 1 || this.index === this.end) {
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return null;
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}
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return this.items[this.index];
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}
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}
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export class ArrayNavigator<T> extends ArrayIterator<T> implements INavigator<T> {
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constructor(items: T[], start: number = 0, end: number = items.length) {
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super(items, start, end);
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}
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public current(): T {
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return super.current();
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}
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public previous(): T {
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this.index = Math.max(this.index - 1, this.start - 1);
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return this.current();
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}
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public first(): T {
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this.index = this.start;
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return this.current();
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}
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public last(): T {
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this.index = this.end - 1;
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return this.current();
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}
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public parent(): T {
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return null;
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}
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}
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export class MappedIterator<T, R> implements IIterator<R> {
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constructor(protected iterator: IIterator<T>, protected fn: (item: T) => R) {
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// noop
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}
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next() { return this.fn(this.iterator.next()); }
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}
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export interface INavigator<T> extends IIterator<T> {
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current(): T;
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previous(): T;
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parent(): T;
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first(): T;
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last(): T;
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next(): T;
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}
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export class MappedNavigator<T, R> extends MappedIterator<T, R> implements INavigator<R> {
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constructor(protected navigator: INavigator<T>, fn: (item: T) => R) {
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super(navigator, fn);
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}
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current() { return this.fn(this.navigator.current()); }
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previous() { return this.fn(this.navigator.previous()); }
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parent() { return this.fn(this.navigator.parent()); }
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first() { return this.fn(this.navigator.first()); }
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last() { return this.fn(this.navigator.last()); }
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next() { return this.fn(this.navigator.next()); }
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}
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