<?php
/**
* Zend Framework
*
* LICENSE
*
* This source file is subject to the new BSD license that is bundled
* with this package in the file LICENSE.txt.
* It is also available through the world-wide-web at this URL:
* http://framework.zend.com/license/new-bsd
* If you did not receive a copy of the license and are unable to
* obtain it through the world-wide-web, please send an email
* to license@zend.com so we can send you a copy immediately.
*
* @category Zend
* @package Zend_Memory
* @copyright Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
* @license http://framework.zend.com/license/new-bsd New BSD License
* @version $Id$
*/


/**
* String value object
*
* It's an OO string wrapper.
* Used to intercept string updates.
*
* @category Zend
* @package Zend_Memory
* @copyright Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
* @license http://framework.zend.com/license/new-bsd New BSD License
* @todo also implement Countable for PHP 5.1 but not yet to stay 5.0 compatible
*/
class Zend_Memory_Value implements ArrayAccess {
/**
* Value
*
* @var string
*/
private $_value;

/**
* Container
*
* @var Zend_Memory_Container_Interface
*/
private $_container;

/**
* Boolean flag which signals to trace value modifications
*
* @var boolean
*/
private $_trace;


/**
* Object constructor
*
* @param string $value
* @param Zend_Memory_Container_Movable $container
*/
public function __construct($value, Zend_Memory_Container_Movable $container)
{
$this->_container = $container;

$this->_value = (string)$value;

/**
* Object is marked as just modified by memory manager
* So we don't need to trace followed object modifications and
* object is processed (and marked as traced) when another
* memory object is modified.
*
* It reduces overall numberr of calls necessary to modification trace
*/
$this->_trace = false;
}


/**
* ArrayAccess interface method
* returns true if string offset exists
*
* @param integer $offset
* @return boolean
*/
public function offsetExists($offset)
{
return $offset >= 0 && $offset < strlen($this->_value);
}

/**
* ArrayAccess interface method
* Get character at $offset position
*
* @param integer $offset
* @return string
*/
public function offsetGet($offset)
{
return $this->_value[$offset];
}

/**
* ArrayAccess interface method
* Set character at $offset position
*
* @param integer $offset
* @param string $char
*/
public function offsetSet($offset, $char)
{
$this->_value[$offset] = $char;

if ($this->_trace) {
$this->_trace = false;
$this->_container->processUpdate();
}
}

/**
* ArrayAccess interface method
* Unset character at $offset position
*
* @param integer $offset
*/
public function offsetUnset($offset)
{
unset($this->_value[$offset]);

if ($this->_trace) {
$this->_trace = false;
$this->_container->processUpdate();
}
}


/**
* To string conversion
*
* @return string
*/
public function __toString()
{
return $this->_value;
}


/**
* Get string value reference
*
* _Must_ be used for value access before PHP v 5.2
* or _may_ be used for performance considerations
*
* @internal
* @return string
*/
public function &getRef()
{
return $this->_value;
}

/**
* Start modifications trace
*
* _Must_ be used for value access before PHP v 5.2
* or _may_ be used for performance considerations
*
* @internal
*/
public function startTrace()
{
$this->_trace = true;
}
}