Appending the AppendIterator

example1.php

<?php
    // Define arrays
    $array1 = new ArrayIterator( array('php', 'perl', 'python', 'c') );
    $array2 = new ArrayIterator( array('singleton', 'factory', 'strategy') );
    $array3 = new ArrayIterator( array('yellow', 'blue', 'red', 'white') );

    // Create iterator and add all arrays to it
    $iterator = new AppendIterator();
    $iterator->append($array1);
    $iterator->append($array2);
    $iterator->append($array3);

    foreach($iterator as $key => $item) {
        echo $key . ' = '.$item . PHP_EOL;
    }

example2.php

<?php
    // Define arrays
    $array1 = new ArrayIterator( array('php', 'perl', 'python', 'c') );
    $array2 = new ArrayIterator( array('singleton', 'factory', 'strategy') );
    $array3 = new ArrayIterator( array('yellow', 'blue', 'red', 'white') );

    // Create iterator and add all arrays to it
    $iterator = new MergeIterator();
    $iterator->append($array1);
    $iterator->append($array2);
    $iterator->append($array3);

    foreach($iterator as $key => $item) {
        echo $key . ' = '. $item . PHP_EOL;
    }

example3.php

<?php
    // Define arrays
    $array1 = new ArrayIterator( array('php', 'perl', 'python', 'c') );
    $array2 = new ArrayIterator( array('singleton', 'factory', 'strategy') );
    $array3 = new ArrayIterator( array('yellow', 'blue', 'red', 'white') );

    // Create iterator and add all arrays to it
    $iterator = new MergeIterator();
    $iterator->append($array1);
    $iterator->append($array2);
    $iterator->append($array3);

    foreach($iterator as $key => $item) {
        echo $iterator->getIteratorIndex() . ' ' .
$key . ' = '. $item . PHP_EOL;
    }

example4.php

<?php
    // Define arrays
    $array1 = new ArrayIterator( array('php', 'perl', 'python', 'c') );
    $array2 = new ArrayIterator( array('singleton', 'factory', 'strategy') );
    $array3 = new ArrayIterator( array('yellow', 'blue', 'red', 'white') );

    // Create iterator and add all arrays to it
    $iterator = new MergeIterator();
    $iterator->append('languages', $array1);
    $iterator->append('patterns', $array2);
    $iterator->append('colors', $array3);

    foreach($iterator as $key => $item) {
        echo $iterator->group() . ' : ' .  $key . ' = '. $item . PHP_EOL;
    }

merge1.php

<?php
class MergeIterator extends AppendIterator {
  protected $_position;

  public function next() {
    parent::next();
    $this->_position++;
  }

  public function rewind() {
    parent::rewind();
    $this->_position = 0;
  }

  public function key() {
    return $this->_position;
  }

}

merge2.php

<?php
class MergeIterator extends AppendIterator {
  protected $_position = 0;
  protected $_groups = array();

  public function append ($group, $iterator) {
    parent::append($iterator);
    $this->_groups[] = $group;
  }

  public function group() {
    return $this->_groups[$this->getIteratorIndex()];
  }

  public function next() {
    parent::next();
    $this->_position++;
  }

  public function rewind() {
    parent::rewind();
    $this->_position = 0;
  }

  public function key() {
    return $this->_position;
  }

}