feat: add clear() method to list and queue classes (#1011)

Add an O(1) method to clear a list or queue of all items.

src/tools/Queue.ts

@@ -89,6 +89,12 @@ export class Deque<T> {
         return (this.length > 0 && this.buffer[this.last]) || undefined;
     }
 
+    clear() {
+        this.first = 0;
+        this.last = 0;
+        this.length = 0;
+    }
+
     indexAfter = (index: number) => {
         return (index < this.capacity && index + 1) || 1;
     };

src/tools/list.spec.ts

@@ -17,7 +17,7 @@ test("from empty array", () => {
     expect(l.asArray()).toEqual({});
 });
 
-test("nodeOf from empety list", () => {
+test("nodeOf from empty list", () => {
     const l = new List<number>();
     const [node, index] = l.nodeOf(10);
     expect(node).toBe(undefined);
@@ -441,3 +441,10 @@ test("replace with front to back iterator of list", () => {
     expect(iterator.next()).toBe(false);
     expect(l.asArray()).toEqual({ 1: 10, 2: 40, 3: 30 });
 });
+
+test("cleared list is empty", () => {
+    const l = new List<number>();
+    l.fromArray({ 1: 10, 2: 20, 3: 30 });
+    l.clear();
+    expect(l.isEmpty()).toBe(true);
+});

src/tools/list.ts

@@ -95,6 +95,11 @@ export class List<T> {
         return (this.head && this.head.prev.value) || undefined;
     }
 
+    clear() {
+        this.head = undefined;
+        this.length = 0;
+    }
+
     backToFrontIterator(): Iterator<T> {
         return new ListBackToFrontIterator<T>(this);
     }

src/tools/queue.spec.ts

@@ -650,3 +650,10 @@ test("replace with front to back iterator of queue", () => {
     expect(iterator.next()).toBe(false);
     expect(q.asArray()).toEqual({ 1: 10, 2: 40, 3: 30 });
 });
+
+test("cleared queue is empty", () => {
+    const q = new Deque<number>();
+    q.fromArray({ 1: 10, 2: 20, 3: 30 });
+    q.clear();
+    expect(q.isEmpty()).toBe(true);
+});