implement and test Array List data structure

src/data-structures/array-list/ArrayList.js

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+import Comparator from '../../utils/comparator/Comparator';
+
+export default class ArrayList {
+
+    constructor(comparatorFunction) {
+        this.comparator = new Comparator(comparatorFunction);
+        this.container = [];
+        this.size = 0;
+    }
+
+    prepend(value) {
+        return this.insert(0, value);
+    }
+
+    append(value) {
+        return this.insert(this.getSize(), value);
+    }
+
+    insert(index, value) {
+        if (index < 0 || index > this.getSize()) {
+            return false;
+        }
+
+        if (this.container.length === this.getSize()) {
+            this.container.length = this.container.length * 2;
+        }
+
+        for (let i = this.getSize(); i > index; i--) {
+            this.container[i] = this.container[i - 1];
+        }
+
+        this.container[index] = value;
+        ++this.size;
+        return true;
+    }
+
+    get(index) {
+        return this.container[index];
+    }
+
+    delete(value) {
+        const originSize = this.getSize();
+        for (let i = 0; i < this.getSize(); i++) {
+            if (this.comparator.equal(this.container[i], value)) {
+                this.deleteAt(i);
+            }
+        }
+        return originSize != this.getSize();
+    }
+
+    deleteAt(index) {
+        const value = this.container[index];
+        for (let i = index + 1; i < this.getSize(); i++) {
+            this.container[i - 1] = this.container[i];
+        }
+        --this.size;
+        return value;
+    }
+
+    getSize() {
+        return this.size;
+    }
+
+    isEmpty() {
+        return this.getSize() === 0;
+    }
+
+    reverse() {
+        for (let i = 0; i < this.getSize() / 2; i++) {
+            let backwardIndex = this.getSize() - 1 -  i;
+            const temp = this.container[i];
+            this.container[i] = this.container[backwardIndex];
+            this.container[backwardIndex] = temp;
+        }
+    }
+
+    toString(callback) {
+        const list = [...this.container];
+        list.length = this.getSize();
+        return list.map(v => callback ? callback(v) : v).toString();
+    }
+}

src/data-structures/array-list/__test__/ArrayList.test.js

@@ -0,0 +1,159 @@
+import ArrayList from '../ArrayList';
+
+describe('ArrayList', () => {
+
+    it('should create empty array list', () => {
+        const list = new ArrayList();
+        
+        expect(list.isEmpty()).toBe(true);
+        expect(list.getSize()).toBe(0);
+    });
+
+    it('should prepend value to array list', () => {
+        const list = new ArrayList();
+        list.prepend(1);
+
+        expect(list.isEmpty()).toBe(false);
+        expect(list.getSize()).toBe(1);
+        expect(list.toString()).toBe('1');
+
+        list.prepend(2);
+        list.prepend(3);
+
+        expect(list.getSize()).toBe(3);
+        expect(list.toString()).toBe('3,2,1');
+    });
+
+    it('should append value to array list', () => {
+        const list = new ArrayList();
+        list.append(1);
+
+        expect(list.isEmpty()).toBe(false);
+        expect(list.getSize()).toBe(1);
+        expect(list.toString()).toBe('1');
+
+        list.append(2);
+        list.append(3);
+
+        expect(list.getSize()).toBe(3);
+        expect(list.toString()).toBe('1,2,3');
+    });
+
+    it('should insert value by index to array list', () => {
+        const list = new ArrayList();
+        list.append(1);
+        list.append(3);
+
+        expect(list.getSize()).toBe(2);
+        expect(list.toString()).toBe('1,3');
+
+        list.insert(0, 0);
+        list.insert(2, 2);
+        list.insert(4, 4);
+
+        expect(list.getSize()).toBe(5);
+        expect(list.toString()).toBe('0,1,2,3,4');
+    });
+
+    it('should get value by index from array list', () => {
+        const list = new ArrayList();
+        list.append(1);
+        list.append(2);
+        list.append(3);
+
+        expect(list.toString()).toBe('1,2,3');
+        expect(list.get(0)).toBe(1);
+        expect(list.get(1)).toBe(2);
+        expect(list.get(2)).toBe(3);
+    });
+
+    it('should be able to insert objects to array list', () => {
+        const list = new ArrayList();
+        list.append({value: 1, key: 'a'});
+        list.append({value: 2, key: 'b'});
+        list.append({value: 3, key: 'c'});
+
+        expect(list.get(0)).toEqual({value: 1, key: 'a'});
+        expect(list.get(1)).toEqual({value: 2, key: 'b'});
+        expect(list.get(2)).toEqual({value: 3, key: 'c'});
+    });
+
+    it('should delete value from array list', () => {
+        const list = new ArrayList();
+        list.append(1);
+        list.append(2);
+        list.append(3);
+
+        expect(list.toString()).toBe('1,2,3');
+
+        list.delete(2);
+
+        expect(list.toString()).toBe('1,3');
+
+        list.delete(1);
+
+        expect(list.toString()).toBe('3');
+
+        list.delete(3);
+
+        expect(list.toString()).toBe('');
+        expect(list.isEmpty()).toBe(true);
+        expect(list.getSize()).toBe(0);
+    });
+
+    it('should delete value by index from array list', () => {
+        const list = new ArrayList();
+        list.append(1);
+        list.append(2);
+        list.append(3);
+        list.append(4);
+
+        expect(list.getSize()).toBe(4);
+        expect(list.toString()).toBe('1,2,3,4');
+        expect(list.deleteAt(2)).toBe(3);
+        expect(list.toString()).toBe('1,2,4');
+        expect(list.deleteAt(0)).toBe(1);
+        expect(list.toString()).toBe('2,4');
+        expect(list.deleteAt(1)).toBe(4);
+        expect(list.toString()).toBe('2');
+        expect(list.deleteAt(0)).toBe(2);
+        expect(list.toString()).toBe('');
+        expect(list.isEmpty()).toBe(true);
+        expect(list.getSize()).toBe(0);
+    });
+
+    it('should reverse array list', () => {
+        const list = new ArrayList();
+        list.append(1);
+        list.append(2);
+        list.append(3);
+
+        expect(list.toString()).toBe('1,2,3');
+
+        list.reverse();
+
+        expect(list.toString()).toBe('3,2,1');
+    });
+
+    it('should show size of array list', () => {
+        const list = new ArrayList();
+
+        expect(list.getSize()).toBe(0);
+
+        list.append(1);
+        list.append(2);
+        list.append(3);
+
+        expect(list.getSize()).toBe(3);
+    });
+
+    it('should check if array list is empty', () => {
+        const list = new ArrayList();
+        
+        expect(list.isEmpty()).toBe(true);
+
+        list.append(1);
+
+        expect(list.isEmpty()).toBe(false);
+    });
+});