chapter 03: [Stacks]

Author: loiane

.gitignore

@@ -7,3 +7,4 @@ coverage.lcov
 mochawesome-report/*
 dist/js/*
 dist/ts/*
+snippet.js

examples/chapter03/01-Stack.js

@@ -1,5 +1,5 @@
 import Stack from './../../src/js/data-structures/stack.js'; // ES2015 modules
-import StackArray from './../../src/js/data-structures/stack-array.js'; // ES2015 modules
+// import StackArray from './../../src/js/data-structures/stack-array.js'; // ES2015 modules
 // const Stack = require('../../dist/js/data-structures/stack'); // for node
 // const Stack = stack; // older browsers - remove from html script import: type="module"
 
@@ -8,6 +8,7 @@ const stack = new Stack(); // new StackArray();
 // using WeakMap to store Stack items we ensure true privacy
 // console.log(Object.getOwnPropertyNames(stack));
 // console.log(Object.keys(stack));
+// console.log(stack.items);
 
 console.log('stack.isEmpty() => ', stack.isEmpty()); // outputs true
 

examples/chapter03/01-StackWeakMap.js

@@ -0,0 +1,70 @@
+// @ts-check
+
+
+const _items = new WeakMap();
+const _count = new WeakMap();
+
+class Stack {
+  constructor() {
+    _count.set(this, 0);
+    _items.set(this, {});
+  }
+
+  push(element) {
+    const items = _items.get(this);
+    const count = _count.get(this);
+    items[count] = element;
+    _count.set(this, count + 1);
+  }
+
+  pop() {
+    if (this.isEmpty()) {
+      return undefined;
+    }
+    const items = _items.get(this);
+    let count = _count.get(this);
+    count--;
+    _count.set(this, count);
+    const result = items[count];
+    delete items[count];
+    return result;
+  }
+
+  peek() {
+    if (this.isEmpty()) {
+      return undefined;
+    }
+    const items = _items.get(this);
+    const count = _count.get(this);
+    return items[count - 1];
+  }
+
+  isEmpty() {
+    return _count.get(this) === 0;
+  }
+
+  size() {
+    return _count.get(this);
+  }
+
+  clear() {
+    /* while (!this.isEmpty()) {
+        this.pop();
+      } */
+    _count.set(this, 0);
+    _items.set(this, {});
+  }
+
+  toString() {
+    if (this.isEmpty()) {
+      return '';
+    }
+    const items = _items.get(this);
+    const count = _count.get(this);
+    let objString = `${items[0]}`;
+    for (let i = 1; i < count; i++) {
+      objString = `${objString},${items[i]}`;
+    }
+    return objString;
+  }
+}

examples/chapter03/03-DecimalToBinary.js

@@ -3,10 +3,11 @@ const baseConverter = PacktDataStructuresAlgorithms.baseConverter;
 
 // 233 == 11101001
 // 2x(10x10) + 3x(10) + 3x(1)
-console.log(decimalToBinary(233));
-console.log(decimalToBinary(10));
-console.log(decimalToBinary(1000));
+console.log(decimalToBinary(233)); // 11101001
+console.log(decimalToBinary(10)); // 1010
+console.log(decimalToBinary(1000)); // 1111101000
 
-console.log(baseConverter(100345, 2));
-console.log(baseConverter(100345, 8));
-console.log(baseConverter(100345, 16));
+console.log(baseConverter(100345, 2)); // 11000011111111001
+console.log(baseConverter(100345, 8)); // 303771
+console.log(baseConverter(100345, 16)); // 187F9
+console.log(baseConverter(100345, 35)); // 2BW0

package.json

@@ -24,7 +24,7 @@
     "test:js": "mocha --compilers js:babel-core/register ./test/js/**/*.spec.js --reporter mochawesome",
     "test:ts": "mocha -r ts-node/register --recursive ./test/ts/**/*.spec.ts",
     "test": "npm run test:js && npm run test:ts",
-    "dev": "npm run clean && npm run lint && npm run generate-report",
+    "dev": "npm run clean && npm run lint && npm run webpack && npm run generate-report",
     "coverage": "npm run generate-report && nyc report --reporter=text-lcov > coverage.lcov && codecov",
     "generate-report": "nyc --report-dir coverage npm run test && nyc report --reporter=text",
     "go": "npm run clean && npm run lint && npm run build && npm run test",

src/js/data-structures/stack-array.js

@@ -2,37 +2,37 @@
 
 export default class StackArray {
   constructor() {
-    this._items = [];
+    this.items = [];
   }
   push(element) {
-    this._items.push(element);
+    this.items.push(element);
   }
 
   pop() {
-    return this._items.pop();
+    return this.items.pop();
   }
 
   peek() {
-    return this._items[this._items.length - 1];
+    return this.items[this.items.length - 1];
   }
 
   isEmpty() {
-    return this._items.length === 0;
+    return this.items.length === 0;
   }
 
   size() {
-    return this._items.length;
+    return this.items.length;
   }
 
   clear() {
-    this._items = [];
+    this.items = [];
   }
 
   toArray() {
-    return this._items;
+    return this.items;
   }
 
   toString() {
-    return this._items.toString();
+    return this.items.toString();
   }
 }

src/js/data-structures/stack.js

@@ -1,69 +1,49 @@
 // @ts-check
 
-
-const _items = new WeakMap();
-const _count = new WeakMap();
-
 export default class Stack {
   constructor() {
-    _count.set(this, 0);
-    _items.set(this, {});
+    this.count = 0;
+    this.items = {};
   }
-
   push(element) {
-    const items = _items.get(this);
-    const count = _count.get(this);
-    items[count] = element;
-    _count.set(this, count + 1);
+    this.items[this.count] = element;
+    this.count++;
   }
-
   pop() {
     if (this.isEmpty()) {
       return undefined;
     }
-    const items = _items.get(this);
-    let count = _count.get(this);
-    count--;
-    _count.set(this, count);
-    const result = items[count];
-    delete items[count];
+    this.count--;
+    const result = this.items[this.count];
+    delete this.items[this.count];
     return result;
   }
-
   peek() {
     if (this.isEmpty()) {
       return undefined;
     }
-    const items = _items.get(this);
-    const count = _count.get(this);
-    return items[count - 1];
+    return this.items[this.count - 1];
   }
-
   isEmpty() {
-    return _count.get(this) === 0;
+    return this.count === 0;
   }
-
   size() {
-    return _count.get(this);
+    return this.count;
   }
-
   clear() {
     /* while (!this.isEmpty()) {
         this.pop();
       } */
-    _count.set(this, 0);
-    _items.set(this, {});
+    this.items = {};
+    this.count = 0;
   }
-
   toString() {
     if (this.isEmpty()) {
       return '';
     }
-    const items = _items.get(this);
-    const count = _count.get(this);
-    let objString = `${items[0]}`;
-    for (let i = 1; i < count; i++) {
-      objString = `${objString},${items[i]}`;
+    let objString = `${this.items[0]}`;
+    for (let i = 1; i < this.count; i++) {
+      objString = `${objString},${this.items[i]}`;
     }
     return objString;
   }