use ES6 Map if we can (#602)

src/Common/ArrayHashMap.ts

@@ -1,49 +1,9 @@
-import { HashMap } from "./HashMap";
-
 /**
  * Hash map of arrays which allows to:
  * - push an item by key: add to array and create array if needed
  * - remove item by key: remove from array and delete array if needed
  */
-
-export class ArrayHashMap<T> {
-  private store: HashMap<T[]>;
-
-  constructor() {
-    this.store = new HashMap();
-  }
-
-  public has(key: string): boolean {
-    return this.store.has(key);
-  }
-
-  public get(key: string): T[] {
-    return this.store.get(key);
-  }
-
-  public size(): number {
-    return this.store.size();
-  }
-
-  public clear(): void {
-    this.store.clear();
-  }
-
-  public keys(): string[] {
-    return this.store.keys();
-  }
-
-  public delete(key: string): boolean {
-    return this.store.delete(key);
-  }
-
-  public forEach(key: string, iteratorFct: (value: T) => void) {
-    const values = this.store.get(key);
-    if (values) {
-      values.forEach((value) => iteratorFct(value));
-    }
-  }
-
+export class ArrayHashMap<T> extends Map<string, T[]> {
   /**
    * Insert item into array.
    * If no array, create one.
@@ -52,16 +12,8 @@ export class ArrayHashMap<T> {
    * @param item
    */
   public push(key: string, item: T): void {
-    let itemsArray: T[] = this.store.get(key);
-    if (!itemsArray) {
-      itemsArray = [item];
-      this.store.set(key, itemsArray);
-      return;
-    }
-
-    if (itemsArray.indexOf(item) === -1) {
-      itemsArray.push(item);
-    }
+    const array = this.get(key);
+    array ? array.includes(item) || array.push(item) : this.set(key, [item]);
   }
 
   /**
@@ -70,18 +22,11 @@ export class ArrayHashMap<T> {
    * @param key
    * @param itemToRemove
    */
-  public remove(key: string, itemToRemove: T) {
-    if (!this.store.has(key)) {
-      return;
-    }
-
-    const itemsArray = this.store.get(key);
-    const index = itemsArray.indexOf(itemToRemove);
-    if (index >= 0) {
-      itemsArray.splice(index, 1);
-      if (itemsArray.length === 0) {
-        this.store.delete(key);
-      }
+  public remove(key: string, itemToRemove: T): void {
+    const array = this.get(key);
+    if (array) {
+      const remaining = array.filter((item) => item !== itemToRemove);
+      remaining.length ? this.set(key, remaining) : this.delete(key);
     }
   }
 }

src/Common/HashMap.test.ts

@@ -1,70 +0,0 @@
-import { HashMap } from "./HashMap";
-
-describe("HashMap", () => {
-  it("should test if key/val exists", () => {
-    const map = new HashMap<number>();
-    map.set("a", 123);
-
-    expect(map.has("a")).toBe(true);
-    expect(map.has("b")).toBe(false);
-  });
-
-  it("should get object back", () => {
-    const map = new HashMap<string>();
-    map.set("a", "123");
-    map.set("a", "456");
-
-    expect(map.get("a")).toBe("456");
-    expect(map.get("a")).not.toBe("123");
-  });
-
-  it("should return the right size", () => {
-    const map = new HashMap<string>();
-    map.set("a", "123");
-    map.set("b", "456");
-
-    expect(map.size()).toBe(2);
-  });
-
-  it("should be iterable", () => {
-    const map = new HashMap<number>();
-    map.set("a", 1);
-    map.set("b", 10);
-    map.set("c", 100);
-    map.set("d", 1000);
-
-    let i = 0;
-    map.forEach((key: string, value: number) => {
-      i += value;
-    });
-    expect(i).toBe(1111);
-  });
-
-  it("should be deleted", () => {
-    const map = new HashMap<number>();
-    map.set("a", 1);
-    map.set("b", 10);
-
-    expect(map.delete("a")).toBe(true);
-    expect(map.delete("c")).toBe(false);
-    expect(map.has("a")).toBe(false);
-    expect(map.has("b")).toBe(true);
-  });
-
-  it("should clear", () => {
-    const map = new HashMap<number>();
-    map.set("a", 1);
-    map.clear();
-    expect(map.size()).toBe(0);
-    expect(map.has("a")).toBe(false);
-  });
-
-  it("should return all keys", () => {
-    const map = new HashMap<number>();
-    map.set("a", 1);
-    map.set("b", 1);
-    expect(map.keys()).toEqual(["a", "b"]);
-    map.clear();
-    expect(map.keys().length).toBe(0);
-  });
-});

src/Common/HashMap.ts

@@ -1,45 +0,0 @@
-/**
- * Simple hashmap implementation that doesn't rely on ES6 Map nor polyfills
- */
-export class HashMap<T> {
-  constructor(private container: { [key: string]: T } = {}) {}
-
-  public has(key: string): boolean {
-    return this.container.hasOwnProperty(key);
-  }
-
-  public set(key: string, value: T): void {
-    this.container[key] = value;
-  }
-
-  public get(key: string): T {
-    return this.container[key];
-  }
-
-  public size(): number {
-    return Object.keys(this.container).length;
-  }
-
-  public delete(key: string): boolean {
-    if (this.has(key)) {
-      delete this.container[key];
-      return true;
-    }
-
-    return false;
-  }
-
-  public clear(): void {
-    this.container = {};
-  }
-
-  public keys(): string[] {
-    return Object.keys(this.container);
-  }
-
-  public forEach(iteratorFct: (key: string, value: T) => void) {
-    for (const k in this.container) {
-      iteratorFct(k, this.container[k]);
-    }
-  }
-}

src/Common/ObjectCache.test.ts

@@ -7,7 +7,7 @@ describe("Object cache", () => {
     cache.set("b", 2);
     cache.set("c", 3);
     cache.set("d", 4);
-    expect(cache.size()).toBe(2);
+    expect(cache.size).toBe(2);
   });
 
   it("should remove first added element to keep size at limit", () => {

src/Common/ObjectCache.ts

@@ -1,56 +1,27 @@
-import { HashMap } from "./HashMap";
-
-export class ObjectCache<T> extends HashMap<T> {
-  private keyQueue: string[]; // Last touched key FIFO to purge cache if too big.
-  private maxNbElements: number;
-
-  public constructor(maxNbElements: number) {
+export class ObjectCache<T> extends Map<string, T> {
+  constructor(private limit: number) {
     super();
-    this.keyQueue = [];
-    this.maxNbElements = maxNbElements;
-    this.clear();
   }
 
-  public clear(): void {
-    super.clear();
-    this.keyQueue = [];
+  public get(key: string): T | undefined {
+    return this.touch(key);
   }
 
-  public get(key: string): T {
-    this.markKeyAsTouched(key);
-    return super.get(key);
-  }
-
-  public set(key: string, value: T): void {
-    super.set(key, value);
-
-    this.markKeyAsTouched(key);
-
-    if (super.size() > this.maxNbElements && key !== this.keyQueue[0]) {
-      this.reduceCacheSize();
+  public set(key: string, value: T): this {
+    if (this.size === this.limit) {
+      this.delete(this.keys().next().value);
     }
+
+    return this.touch(key, value), this;
   }
 
-  /**
-   * Invalidate elements to keep the total number below the limit
-   */
-  private reduceCacheSize(): void {
-    // remove a key
-    const oldKey = this.keyQueue.shift();
-    if (oldKey) {
-      super.delete(oldKey);
+  private touch(key: string, value = super.get(key)) {
+    // Map keeps (re) insertion order according to ES6 spec
+    if (value) {
+      this.delete(key);
+      super.set(key, value);
     }
-  }
 
-  /**
-   * Bubble up this key as new.
-   * @param key
-   */
-  private markKeyAsTouched(key: string) {
-    const n = this.keyQueue.indexOf(key);
-    if (n > -1) {
-      this.keyQueue.splice(n, 1);
-    }
-    this.keyQueue.push(key);
+    return value;
   }
 }