added iterator pattern and basic sample

Iterator/Iterator.php

@@ -0,0 +1,109 @@
+<?php
+
+namespace DesignPatterns;
+
+/**
+ * iterator pattern
+ *
+ * Purpose:
+ * to make an object iterable
+ *
+ * Examples:
+ * - to process a file line by line by just running over all lines (which have an object representation) for a file
+ *   (which of course is an object, too)
+ *
+ * Note:
+ * Standard PHP Library (SPL) defines an interface Iterator which is best suited for this!
+ * Often you would want to implement the Countable interface too, to allow count($object) on your iterable object
+ *
+ * THIS EXAMPLE ALSO APPLIES THE COMPOSITE PATTERN
+ *
+ */
+class File
+{
+    protected $_rowset;
+
+    protected $_pathName;
+
+    public function __construct($pathName)
+    {
+        $this->_rowset = new Rowset($this);
+    }
+
+    public function process()
+    {
+        $this->_rowset->process();
+    }
+}
+
+class Rowset implements Iterator
+{
+    protected $_currentRow;
+
+    protected $_file;
+
+    public function __construct($file)
+    {
+        $this->_file = $file;
+    }
+
+    /**
+     * composite pattern: run through all rows and process them
+     *
+     * @return void
+     */
+    public function process()
+    {
+        // this actually calls rewind(), { next(), valid(), key() and current() :}
+        foreach ($this as $line => $row) {
+            $row->process();
+        }
+    }
+
+    public function rewind()
+    {
+        // seek to first line from $this->_file
+    }
+
+    public function next()
+    {
+        // read the next line from $this->_file
+        if (!$eof) {
+            $data = ''; // get the line
+            $this->_currentRow = new Row($data);
+        } else {
+            $this->_currentRow = null;
+        }
+    }
+
+    public function current()
+    {
+        return $this->_currentRow;
+    }
+
+    public function valid()
+    {
+        return null !== $this->_currentRow;
+    }
+
+    public function key()
+    {
+        // you would want to increment this in next() or whatsoever
+        return $this->_lineNumber;
+    }
+}
+
+class Row
+{
+    protected $_data;
+
+    public function __construct($data)
+    {
+        $this->_data = $data;
+    }
+
+    public function process()
+    {
+        // do some fancy things here ...
+    }
+}