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69 lines
2.3 KiB
TypeScript
69 lines
2.3 KiB
TypeScript
/*
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Copyright 2020 The Matrix.org Foundation C.I.C.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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import { arrayDiff, arrayMerge, arrayUnion } from "./arrays";
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/**
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* Determines the keys added, changed, and removed between two Maps.
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* For changes, simple triple equal comparisons are done, not in-depth tree checking.
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* @param a The first Map. Must be defined.
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* @param b The second Map. Must be defined.
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* @returns The difference between the keys of each Map.
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*/
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export function mapDiff<K, V>(a: Map<K, V>, b: Map<K, V>): { changed: K[], added: K[], removed: K[] } {
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const aKeys = [...a.keys()];
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const bKeys = [...b.keys()];
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const keyDiff = arrayDiff(aKeys, bKeys);
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const possibleChanges = arrayUnion(aKeys, bKeys);
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const changes = possibleChanges.filter(k => a.get(k) !== b.get(k));
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return {changed: changes, added: keyDiff.added, removed: keyDiff.removed};
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}
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/**
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* Gets all the key changes (added, removed, or value difference) between two Maps.
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* Triple equals is used to compare values, not in-depth tree checking.
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* @param a The first Map. Must be defined.
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* @param b The second Map. Must be defined.
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* @returns The keys which have been added, removed, or changed between the two Maps.
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*/
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export function mapKeyChanges<K, V>(a: Map<K, V>, b: Map<K, V>): K[] {
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const diff = mapDiff(a, b);
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return arrayMerge(diff.removed, diff.added, diff.changed);
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}
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/**
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* A Map<K, V> with added utility.
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*/
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export class EnhancedMap<K, V> extends Map<K, V> {
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public constructor(entries?: Iterable<[K, V]>) {
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super(entries);
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}
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public getOrCreate(key: K, def: V): V {
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if (this.has(key)) {
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return this.get(key);
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}
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this.set(key, def);
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return def;
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}
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public remove(key: K): V {
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const v = this.get(key);
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this.delete(key);
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return v;
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}
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}
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