mvp bfixarrayqueue

Author: shadowcodex

lib/queues.js

@@ -98,7 +98,7 @@ class BFltArrayQueue {
   }
 
   isFull() {
-    return this.length === queue.length;
+    return this.length === this.queue.length;
   }
 
   isEmpty() {
@@ -139,7 +139,56 @@ class BFltArrayQueue {
 /**
  * Implements a bounded queue using an array with the fixed front method.
  */
-class BFixArrayQueue {}
+class BFixArrayQueue {
+  constructor(size = (DEFAULT_SIZE = 1000)) {
+    this.queue = [];
+    for (let i = 0; i < size; i++) {
+      this.queue[i] = null;
+    }
+    this.rear = -1;
+    this.length = 0;
+  }
+
+  isFull() {
+    return this.rear === this.queue.length - 1;
+  }
+
+  isEmpty() {
+    return this.rear === -1;
+  }
+
+  enqueue(data) {
+    if (isFull()) {
+      throw new Error('Enqueue attempted on a full queue.');
+    } else {
+      this.rear++;
+      this.queue[this.rear] = data;
+    }
+  }
+
+  dequeue() {
+    if (isEmpty()) {
+      throw new Error('Dequeue attempted on empty queue.');
+    } else {
+      const toReturn = this.queue[0];
+
+      // this array shift is why the fixed front method is inefficient.
+      for (let i = 1; i < this.rear; i++) {
+        this.queue[i - 1] = this.queue[i];
+      }
+      this.rear--;
+      return toReturn;
+    }
+  }
+
+  peek() {
+    return this.queue[this.front];
+  }
+
+  length() {
+    return this.rear + 1;
+  }
+}
 
 module.exports = {
   LinkedQueue,