library/Zend/Memory/Value.php

   1 <?php
   2 /**
   3  * Zend Framework
   4  *
   5  * LICENSE
   6  *
   7  * This source file is subject to the new BSD license that is bundled
   8  * with this package in the file LICENSE.txt.
   9  * It is also available through the world-wide-web at this URL:
  10  * http://framework.zend.com/license/new-bsd
  11  * If you did not receive a copy of the license and are unable to
  12  * obtain it through the world-wide-web, please send an email
  13  * to license@zend.com so we can send you a copy immediately.
  14  *
  15  * @category   Zend
  16  * @package    Zend_Memory
  17  * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
  18  * @license    http://framework.zend.com/license/new-bsd     New BSD License
  19  * @version    $Id: Value.php 16971 2009-07-22 18:05:45Z mikaelkael $
  20  */
  21
  22
  23 /**
  24  * String value object
  25  *
  26  * It's an OO string wrapper.
  27  * Used to intercept string updates.
  28  *
  29  * @package    Zend_Memory
  30  * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
  31  * @license    http://framework.zend.com/license/new-bsd     New BSD License
  32  * @todo       also implement Countable for PHP 5.1 but not yet to stay 5.0 compatible
  33  */
  34 class Zend_Memory_Value implements ArrayAccess {
  35     /**
  36      * Value
  37      *
  38      * @var string
  39      */
  40     private $_value;
  41
  42     /**
  43      * Container
  44      *
  45      * @var Zend_Memory_Container_Interface
  46      */
  47     private $_container;
  48
  49     /**
  50      * Boolean flag which signals to trace value modifications
  51      *
  52      * @var boolean
  53      */
  54     private $_trace;
  55
  56
  57     /**
  58      * Object constructor
  59      *
  60      * @param string $value
  61      * @param Zend_Memory_Container_Movable $container
  62      */
  63     public function __construct($value, Zend_Memory_Container_Movable $container)
  64     {
  65         $this->_container = $container;
  66
  67         $this->_value = (string)$value;
  68
  69         /**
  70          * Object is marked as just modified by memory manager
  71          * So we don't need to trace followed object modifications and
  72          * object is processed (and marked as traced) when another
  73          * memory object is modified.
  74          *
  75          * It reduces overall numberr of calls necessary to modification trace
  76          */
  77         $this->_trace = false;
  78     }
  79
  80
  81     /**
  82      * ArrayAccess interface method
  83      * returns true if string offset exists
  84      *
  85      * @param integer $offset
  86      * @return boolean
  87      */
  88     public function offsetExists($offset)
  89     {
  90         return $offset >= 0  &&  $offset < strlen($this->_value);
  91     }
  92
  93     /**
  94      * ArrayAccess interface method
  95      * Get character at $offset position
  96      *
  97      * @param integer $offset
  98      * @return string
  99      */
 100     public function offsetGet($offset)
 101     {
 102         return $this->_value[$offset];
 103     }
 104
 105     /**
 106      * ArrayAccess interface method
 107      * Set character at $offset position
 108      *
 109      * @param integer $offset
 110      * @param string $char
 111      */
 112     public function offsetSet($offset, $char)
 113     {
 114         $this->_value[$offset] = $char;
 115
 116         if ($this->_trace) {
 117             $this->_trace = false;
 118             $this->_container->processUpdate();
 119         }
 120     }
 121
 122     /**
 123      * ArrayAccess interface method
 124      * Unset character at $offset position
 125      *
 126      * @param integer $offset
 127      */
 128     public function offsetUnset($offset)
 129     {
 130         unset($this->_value[$offset]);
 131
 132         if ($this->_trace) {
 133             $this->_trace = false;
 134             $this->_container->processUpdate();
 135         }
 136     }
 137
 138
 139     /**
 140      * To string conversion
 141      *
 142      * @return string
 143      */
 144     public function __toString()
 145     {
 146         return $this->_value;
 147     }
 148
 149
 150     /**
 151      * Get string value reference
 152      *
 153      * _Must_ be used for value access before PHP v 5.2
 154      * or _may_ be used for performance considerations
 155      *
 156      * @internal
 157      * @return string
 158      */
 159     public function &getRef()
 160     {
 161         return $this->_value;
 162     }
 163
 164     /**
 165      * Start modifications trace
 166      *
 167      * _Must_ be used for value access before PHP v 5.2
 168      * or _may_ be used for performance considerations
 169      *
 170      * @internal
 171      */
 172     public function startTrace()
 173     {
 174         $this->_trace = true;
 175     }
 176 }