Adding the Stack Data Structure (#137)

* Adding the Stack Data Structure

* Fixing the Lint Issue

Author: shivani51yadav

DIRECTORY.md

@@ -20,6 +20,7 @@
   * [Doublylinkedlist](./DataStructures/DoublyLinkedList.php)
   * [Node](./DataStructures/Node.php)
   * [Singlylinkedlist](./DataStructures/SinglyLinkedList.php)
+  * [Stack](./DataStructures/Stack.php)
 
 ## Graphs
   * [Breadthfirstsearch](./Graphs/BreadthFirstSearch.php)
@@ -103,6 +104,7 @@
   * Datastructures
     * [Doublylinkedlisttest](./tests/DataStructures/DoublyLinkedListTest.php)
     * [Singlylinkedlisttest](./tests/DataStructures/SinglyLinkedListTest.php)
+    * [Stacktest](./tests/DataStructures/StackTest.php)
   * Graphs
     * [Breadthfirstsearchtest](./tests/Graphs/BreadthFirstSearchTest.php)
     * [Depthfirstsearchtest](./tests/Graphs/DepthFirstSearchTest.php)

DataStructures/Stack.php

@@ -0,0 +1,85 @@
+<?php
+
+/**
+ * Stack Implementation in PHP
+ */
+class Stack
+{
+    private array $stack = [];
+
+    public function __construct(array $array = [])
+    {
+        $this->stack = $array;
+    }
+
+    public function __destruct()
+    {
+        unset($this->stack);
+    }
+
+
+    public function push($data): void
+    {
+        array_push($this->stack, $data);
+    }
+
+    public function pop()
+    {
+        return array_pop($this->stack);
+    }
+
+    public function peek()
+    {
+        return $this->stack[count($this->stack) - 1];
+    }
+
+    public function isEmpty(): bool
+    {
+        return empty($this->stack);
+    }
+
+    public function print(): void
+    {
+        echo implode(', ', $this->stack);
+    }
+
+    public function __toString(): string
+    {
+        return implode(', ', $this->stack);
+    }
+
+    public function length(): int
+    {
+        return count($this->stack);
+    }
+
+    public function clear(): void
+    {
+        $this->stack = [];
+    }
+
+    public function search($data): int
+    {
+        return array_search($data, $this->stack);
+    }
+
+    public function toArray(): array
+    {
+        return $this->stack;
+    }
+
+    public function fromArray(array $array): void
+    {
+        $this->stack = $array;
+    }
+
+    public function reverse(): void
+    {
+        $this->stack = array_reverse($this->stack);
+    }
+
+    public function sort(): void
+    {
+        sort($this->stack);
+    }
+}

tests/DataStructures/StackTest.php

@@ -0,0 +1,110 @@
+<?php
+
+use PHPUnit\Framework\TestCase;
+
+require_once __DIR__ . '/../../vendor/autoload.php';
+require_once __DIR__ . '/../../DataStructures/Stack.php';
+
+class StackTest extends TestCase
+{
+    public function testConstruct()
+    {
+        $stack = new Stack([1, 2, 3]);
+        $this->assertEquals([1, 2, 3], $stack->toArray());
+    }
+
+    public function testDestruct()
+    {
+        $stack = new Stack([1, 2, 3]);
+        unset($stack);
+        $this->expectNotToPerformAssertions();
+    }
+
+    public function testPush()
+    {
+        $stack = new Stack();
+        $stack->push(1);
+        $stack->push(2);
+        $stack->push(3);
+        $this->assertEquals([1, 2, 3], $stack->toArray());
+    }
+
+    public function testPop()
+    {
+        $stack = new Stack([1, 2, 3]);
+        $this->assertEquals(3, $stack->pop());
+        $this->assertEquals([1, 2], $stack->toArray());
+    }
+
+    public function testPeek()
+    {
+        $stack = new Stack([1, 2, 3]);
+        $this->assertEquals(3, $stack->peek());
+    }
+
+    public function testIsEmpty()
+    {
+        $stack = new Stack();
+        $this->assertTrue($stack->isEmpty());
+    }
+
+    public function testPrint()
+    {
+        $stack = new Stack([1, 2, 3]);
+        $this->expectOutputString("1, 2, 3");
+        $stack->print();
+    }
+
+    public function testToString()
+    {
+        $stack = new Stack([1, 2, 3]);
+        $this->expectOutputString("1, 2, 3");
+        echo $stack;
+    }
+
+    public function testLength()
+    {
+        $stack = new Stack([1, 2, 3]);
+        $this->assertEquals(3, $stack->length());
+    }
+
+    public function testClear()
+    {
+        $stack = new Stack([1, 2, 3]);
+        $stack->clear();
+        $this->assertEquals([], $stack->toArray());
+    }
+
+    public function testSearch()
+    {
+        $stack = new Stack([1, 2, 3]);
+        $this->assertEquals(2, $stack->search(3));
+    }
+
+    public function testToArray()
+    {
+        $stack = new Stack([1, 2, 3]);
+        $this->assertEquals([1, 2, 3], $stack->toArray());
+    }
+
+    public function testFromArray()
+    {
+        $stack = new Stack();
+        $stack->fromArray([1, 2, 3]);
+        $this->assertEquals([1, 2, 3], $stack->toArray());
+    }
+
+    public function testReverse()
+    {
+        $stack = new Stack([1, 2, 3]);
+        $stack->reverse();
+        $this->assertEquals([3, 2, 1], $stack->toArray());
+    }
+
+    public function testSort()
+    {
+        $stack = new Stack([3, 2, 1]);
+        $stack->sort();
+        $this->assertEquals([1, 2, 3], $stack->toArray());
+    }
+}