Php DS

README.md

@@ -7,6 +7,7 @@ This contains all the programs for data structures that are a part of the syllab
 - [Java](https://github.com/diptangsu/Data-Structures/blob/master/src-java)
 - [Javascript](https://github.com/diptangsu/Data-Structures/blob/master/src-javascript)
 - [Python](https://github.com/diptangsu/Data-Structures/blob/master/src-python) :snake:
+- [Php](https://github.com/diptangsu/Data-Structures/blob/master/src-php)
 
 ---
 # Stack
@@ -62,6 +63,10 @@ A Queue is a linear structure which follows a particular order in which the oper
     - Inserting the new item at the beginning of the Queue.
 - Dequeue()
     - Taking out the last item of the Queue.
+- Peek()
+    - Get the last item of the Queue without remove it.
+- IsEmpty()
+    - Verify if Queue is empty.
 
 ---
 # Tree :deciduous_tree:

src-php/LinkedList.php

@@ -0,0 +1,178 @@
+namespace srcPhp;
+
+use srcPhp\Node;
+
+class LinkedList implements \Iterator {
+
+    private $_firstNode = NULL;
+    private $_lastNode = NULL;
+    private $_totalNode = 0;
+    private $_currentNode = NULL;
+    private $_currentPosition = 0;
+
+    public function insertLast(string $data = NULL) {
+        $newNode = new Node($data);
+        if ($this->_firstNode === NULL) {
+            $this->_firstNode = &$newNode;
+            $this->_lastNode = &$newNode;
+        } else {
+            $currentNode = $this->_lastNode;
+            $currentNode->next = $newNode;
+            $newNode->prev = $currentNode;
+            $this->_lastNode = &$newNode;
+        }
+        $this->_totalNode++;
+        return TRUE;
+    }
+
+    public function insertFirst(string $data = NULL) {
+        $newNode = new Node($data);
+        if ($this->_firstNode === NULL) {
+            $this->_firstNode = &$newNode;
+            $this->_lastNode = &$newNode;
+        } else {
+            $currentFirstNode = $this->_firstNode;
+            $this->_firstNode = &$newNode;
+            $newNode->next = $currentFirstNode;
+            $this->_lastNode = &$currentFirstNode;
+        }
+        $this->_totalNode++;
+        return TRUE;
+    }
+
+    public function insertAt(string $data = NULL, string $index = NULL) {
+        $newNode = new Node($data);
+
+        if ($this->_firstNode) {
+            $previous = NULL;
+            $currentNode = $this->_firstNode;
+            while ($currentNode !== NULL) {
+                if ($currentNode->data === $index) {
+                    $newNode->next = $currentNode;
+                    if ($previous === NULL) {
+                        $this->_firstNode = &$newNode;
+                    } else {
+                        $previous->next = $newNode;
+                    }
+                    $this->_totalNode++;
+                    break;
+                }
+                $previous = $currentNode;
+                $currentNode = $currentNode->next;
+
+            }
+        }
+    }
+
+    public function removeFirst() {
+        if ($this->_firstNode !== NULL) {
+            if ($this->_firstNode->next !== NULL) {
+                $this->_firstNode = $this->_firstNode->next;
+            } else {
+                $this->_firstNode = NULL;
+                $this->_lastNode = NULL;
+            }
+            $this->_totalNode--;
+            return TRUE;
+        }
+        return FALSE;
+    }
+
+    public function removeLast() {
+        if ($this->_firstNode !== NULL) {
+            $currentNode = $this->_firstNode;
+            if ($currentNode->next === NULL) {
+                $this->_firstNode = NULL;
+            } else {
+                $previousNode = NULL;
+
+                while ($currentNode->next !== NULL) {
+                    $previousNode = $currentNode;
+                    $currentNode = $currentNode->next;
+                }
+
+                $previousNode->next = NULL;
+                $this->_lastNode = &$previousNode;
+                $this->_totalNode--;
+                return TRUE;
+            }
+        }
+        return FALSE;
+    }
+
+    public function removeAt(string $index = NULL) {
+        if ($this->_firstNode) {
+            $previous = NULL;
+            $currentNode = $this->_firstNode;
+            while ($currentNode !== NULL) {
+                if ($currentNode->data === $index) {
+                    if ($currentNode->next === NULL) {
+                        $previous->next = NULL;
+                    } else {
+                        $previous->next = $currentNode->next;
+                    }
+
+                    if($currentNode === $this->_lastNode) {
+                        $this->_lastNode = &$previous;
+                    }
+
+                    $this->_totalNode--;
+                    break;
+                }
+                $previous = $currentNode;
+                $currentNode = $currentNode->next;
+            }
+        }
+    }
+
+    public function getFirst() {
+        if ($this->_firstNode !== NULL)
+            return $this->_firstNode->data;
+    }
+
+    public function getLast() {
+        if ($this->_lastNode !== NULL)
+            return $this->_lastNode->data;
+    }
+
+    public function getAt(int $n = 0) {
+        $count = 1;
+        if ($this->_firstNode !== NULL && $n <= $this->_totalNode) {
+            $currentNode = $this->_firstNode;
+            while ($currentNode !== NULL) {
+                if ($count === $n) {
+                    return $currentNode;
+                }
+                $count++;
+                $currentNode = $currentNode->next;
+            }
+        }
+    }
+
+    public function getSize() {
+        return $this->_totalNode;
+    }
+
+    public function current() {
+        return $this->_currentNode->data;
+    }
+
+    public function next() {
+        $this->_currentPosition++;
+        $this->_currentNode = $this->_currentNode->next;
+    }
+
+    public function key() {
+        return $this->_currentPosition;
+    }
+
+    public function rewind() {
+        $this->_currentPosition = 0;
+        $this->_currentNode = $this->_firstNode;
+    }
+
+    public function valid() {
+        return $this->_currentNode !== NULL;
+    }
+
+}

src-php/Node.php

@@ -0,0 +1,14 @@
+namespace srcPhp;
+
+class Node {
+
+    public $data = NULL;
+    public $next = NULL;
+    public $prev = NULL;
+
+    public function __construct(string $data = NULL) {
+        $this->data = $data;
+    }
+
+}
+

src-php/Queue.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace srcPhp;
+
+use srcPhp\LinkedList;
+
+class Queue {
+
+    private $n;
+    private $queue;
+
+    public function __construct(int $n = 20) {
+	    $this->n = $n;
+	    $this->queue = new LinkedList();
+    }
+
+    public function dequeue(): string {
+	    if ($this->isEmpty()) {
+	        throw new UnderflowException('Queue is empty');
+        } else {
+	        $lastItem = $this->peek();
+	        $this->queue->removeFirst();
+	        return $lastItem;
+	    }
+    }
+
+    public function enqueue(string $newItem) {
+	    if ($this->queue->getSize() < $this->n) {
+	        $this->queue->insertLast($newItem);
+	    } else {
+	        throw new OverflowException('Queue is full');
+	    }
+    }
+
+    public function peek(): string {
+	    return $this->queue->getAt(1)->data;
+    }
+
+    public function isEmpty(): bool {
+	    return $this->queue->getSize() == 0;
+    }
+
+}