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) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)
  18  * @license    http://framework.zend.com/license/new-bsd     New BSD License
  19  * @version    $Id$
  20  */
  21
  22
  23 /**
  24  * String value object
  25  *
  26  * It's an OO string wrapper.
  27  * Used to intercept string updates.
  28  *
  29  * @category   Zend
  30  * @package    Zend_Memory
  31  * @copyright  Copyright (c) 2005-2010 Zend Technologies USA Inc. (http://www.zend.com)
  32  * @license    http://framework.zend.com/license/new-bsd     New BSD License
  33  * @todo       also implement Countable for PHP 5.1 but not yet to stay 5.0 compatible
  34  */
  35 class Zend_Memory_Value implements ArrayAccess {
  36     /**
  37      * Value
  38      *
  39      * @var string
  40      */
  41     private $_value;
  42
  43     /**
  44      * Container
  45      *
  46      * @var Zend_Memory_Container_Interface
  47      */
  48     private $_container;
  49
  50     /**
  51      * Boolean flag which signals to trace value modifications
  52      *
  53      * @var boolean
  54      */
  55     private $_trace;
  56
  57
  58     /**
  59      * Object constructor
  60      *
  61      * @param string $value
  62      * @param Zend_Memory_Container_Movable $container
  63      */
  64     public function __construct($value, Zend_Memory_Container_Movable $container)
  65     {
  66         $this->_container = $container;
  67
  68         $this->_value = (string)$value;
  69
  70         /**
  71          * Object is marked as just modified by memory manager
  72          * So we don't need to trace followed object modifications and
  73          * object is processed (and marked as traced) when another
  74          * memory object is modified.
  75          *
  76          * It reduces overall numberr of calls necessary to modification trace
  77          */
  78         $this->_trace = false;
  79     }
  80
  81
  82     /**
  83      * ArrayAccess interface method
  84      * returns true if string offset exists
  85      *
  86      * @param integer $offset
  87      * @return boolean
  88      */
  89     public function offsetExists($offset)
  90     {
  91         return $offset >= 0  &&  $offset < strlen($this->_value);
  92     }
  93
  94     /**
  95      * ArrayAccess interface method
  96      * Get character at $offset position
  97      *
  98      * @param integer $offset
  99      * @return string
 100      */
 101     public function offsetGet($offset)
 102     {
 103         return $this->_value[$offset];
 104     }
 105
 106     /**
 107      * ArrayAccess interface method
 108      * Set character at $offset position
 109      *
 110      * @param integer $offset
 111      * @param string $char
 112      */
 113     public function offsetSet($offset, $char)
 114     {
 115         $this->_value[$offset] = $char;
 116
 117         if ($this->_trace) {
 118             $this->_trace = false;
 119             $this->_container->processUpdate();
 120         }
 121     }
 122
 123     /**
 124      * ArrayAccess interface method
 125      * Unset character at $offset position
 126      *
 127      * @param integer $offset
 128      */
 129     public function offsetUnset($offset)
 130     {
 131         unset($this->_value[$offset]);
 132
 133         if ($this->_trace) {
 134             $this->_trace = false;
 135             $this->_container->processUpdate();
 136         }
 137     }
 138
 139
 140     /**
 141      * To string conversion
 142      *
 143      * @return string
 144      */
 145     public function __toString()
 146     {
 147         return $this->_value;
 148     }
 149
 150
 151     /**
 152      * Get string value reference
 153      *
 154      * _Must_ be used for value access before PHP v 5.2
 155      * or _may_ be used for performance considerations
 156      *
 157      * @internal
 158      * @return string
 159      */
 160     public function &getRef()
 161     {
 162         return $this->_value;
 163     }
 164
 165     /**
 166      * Start modifications trace
 167      *
 168      * _Must_ be used for value access before PHP v 5.2
 169      * or _may_ be used for performance considerations
 170      *
 171      * @internal
 172      */
 173     public function startTrace()
 174     {
 175         $this->_trace = true;
 176     }
 177 }