Dynamic backreferences?

[448191]

$result = preg_replace('/([A-Za-z]*)((_)([A-Za-z]*))*/', '$1::$4', $subject);

 

This only replaces the last match stored in $4. Makes sense, but is there a way I can avoid this without knowing how many times $4 will match?

 

Edit, never mind, I figured it out. I shouldn't repeat the expression in $4. I.e.:

 

Expr.

([A-Za-z]*)((_)([A-Za-z]*))

 

Repl.

 

$1::$4

 

Test

 

Zend_Db_Table_Abstract

 

Result

 

Zend::Db::Table::Abstract

 

 

[nrg_alpha]

If you are just trying to replace the underscore with '::', you could use a simple str_replace:

$str = 'Zend_Db_Table_Abstract';
$str = str_replace('_', '::', $str);
echo $str;

 

Unless I am not understanding something here.. I'm admittedly lost with what you want to achieve with $4...

EDIT:

 

When I test your expression with the source string as 'Zend_Db_Table_Abstract', I get:

Zend::Abstract::

 

Am I missing something?

 

[448191]

I can't replace underscores with double colons, because I'm processing whole classes (the whole of Zend Framework in fact).

 

The problem I had was that I didn't know how to combine a static part with a repeated part (e.g. Zend((_)([A-Za-z]*))). I still don't know how to do that, but it's ok, I've build around it.

 

Example:

 

<?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::Json
* @copyright  Copyright (c) 2005-2008 Zend Technologies USA Inc. (http://www.zend.com)
* @license    http://framework.zend.com/license/new-bsd     New BSD License
*/

/**
* JsonException.
*/
require_once 'Zend/Json/Exception.php';

/**
* Class for encoding to and decoding from JSON.
*
* @category   Zend
* @package    Zend::Json
* @copyright  Copyright (c) 2005-2008 Zend Technologies USA Inc. (http://www.zend.com)
* @license    http://framework.zend.com/license/new-bsd     New BSD License
*/
use Zend::Json::Exception JsonException;
use Zend::Json::Decoder;
use Zend::Json::Encoder;

namespace Zend;

class Json {
    /**
     * How objects should be encoded -- arrays or as StdClass. TYPE_ARRAY is 1
     * so that it is a boolean true value, allowing it to be used with
     * ext/json's functions.
     */
    const TYPE_ARRAY  = 1;
    const TYPE_OBJECT = 0;

     /**
      * To check the allowed nesting depth of the XML tree during xml2json conversion.
      * 
      * @var int
      */
    public static $maxRecursionDepthAllowed=25;

    /**
     * @var bool
     */
    public static $useBuiltinEncoderDecoder = false;

    /**
     * Decodes the given $encodedValue string which is
     * encoded in the JSON format
     *
     * Uses ext/json's json_decode if available.
     *
     * @param string $encodedValue Encoded in JSON format
     * @param int $objectDecodeType Optional; flag indicating how to decode
     * objects. See {@link ZJsonDecoder::decode()} for details.
     * @return mixed
     */
    public static function decode($encodedValue, $objectDecodeType = Zend::Json::TYPE_ARRAY)
    {
        if (function_exists('json_decode') && self::$useBuiltinEncoderDecoder !== true) {
            return json_decode($encodedValue, $objectDecodeType);
        }

        require_once 'Zend/Json/Decoder.php';
        return Decoder::decode($encodedValue, $objectDecodeType);
    }


    /**
     * Encode the mixed $valueToEncode into the JSON format
     *
     * Encodes using ext/json's json_encode() if available.
     *
     * NOTE: Object should not contain cycles; the JSON format
     * does not allow object reference.
     *
     * NOTE: Only public variables will be encoded
     *
     * @param mixed $valueToEncode
     * @param boolean $cycleCheck Optional; whether or not to check for object recursion; off by default
     * @return string JSON encoded object
     */
    public static function encode($valueToEncode, $cycleCheck = false)
    {
        if (function_exists('json_encode') && self::$useBuiltinEncoderDecoder !== true) {
            return json_encode($valueToEncode);
        }

        require_once 'Zend/Json/Encoder.php';
        return Encoder::encode($valueToEncode, $cycleCheck);
    }

    /**  
     * fromXml - Converts XML to JSON  
     *  
     * Converts a XML formatted string into a JSON formatted string.   
     * The value returned will be a string in JSON format.  
     *  
     * The caller of this function needs to provide only the first parameter,   
     * which is an XML formatted String. The second parameter is optional, which   
     * lets the user to select if the XML attributes in the input XML string  
     * should be included or ignored in xml2json conversion.  
     *   
     * This function converts the XML formatted string into a PHP array by   
     * calling a recursive (protected static) function in this class. Then, it   
     * converts that PHP array into JSON by calling the "encode" static funcion.  
     *  
     * Throws a JsonException if the input not a XML formatted string.  
     *  
     * @static  
     * @access public  
     * @param string $xmlStringContents XML String to be converted  
     * @param boolean $ignoreXmlAttributes Include or exclude XML attributes in  
     * the xml2json conversion process.  
     * @return mixed - JSON formatted string on success  
     * @throws JsonException  
     */  
    public static function fromXml ($xmlStringContents, $ignoreXmlAttributes=true) {   
        // Load the XML formatted string into a Simple XML Element object.    
        $simpleXmlElementObject = simplexml_load_string($xmlStringContents);       
     
        // If it is not a valid XML content, throw an exception.      
        if ($simpleXmlElementObject == null) {      
            throw new JsonException('Function fromXml was called with an invalid XML formatted string.');   
        } // End of if ($simpleXmlElementObject == null)   
       
        $resultArray = null;   
         
        // Call the recursive function to convert the XML into a PHP array.   
        $resultArray = self::_processXml($simpleXmlElementObject, $ignoreXmlAttributes);             
  
        // Convert the PHP array to JSON using Zend::Json encode method.   
        // It is just that simple.   
        $jsonStringOutput = self::encode($resultArray);
        return($jsonStringOutput);       
    } // End of function fromXml.  

    /**  
     * _processXml - Contains the logic for xml2json  
     *  
     * The logic in this function is a recursive one.  
     *    
     * The main caller of this function (i.e. fromXml) needs to provide    
     * only the first two parameters i.e. the SimpleXMLElement object and   
     * the flag for ignoring or not ignoring XML attributes. The third parameter   
     * will be used internally within this function during the recursive calls.  
     *   
     * This function converts the SimpleXMLElement object into a PHP array by   
     * calling a recursive (protected static) function in this class. Once all  
     * the XML elements are stored in the PHP array, it is returned to the caller.  
     *  
     * Throws a JsonException if the XML tree is deeper than the allowed limit.  
     *  
     * @static  
     * @access protected  
     * @param SimpleXMLElement $simpleXmlElementObject XML element to be converted  
     * @param boolean $ignoreXmlAttributes Include or exclude XML attributes in  
     * the xml2json conversion process.  
     * @param int $recursionDepth Current recursion depth of this function
     * @return mixed - On success, a PHP associative array of traversed XML elements  
     * @throws JsonException  
     */  
    protected static function _processXml ($simpleXmlElementObject, $ignoreXmlAttributes, $recursionDepth=0) {       
        // Keep an eye on how deeply we are involved in recursion.      
        if ($recursionDepth > self::$maxRecursionDepthAllowed) {      
            // XML tree is too deep. Exit now by throwing an exception.      
            throw new JsonException(   
                "Function _processXml exceeded the allowed recursion depth of " .   
                self::$maxRecursionDepthAllowed);      
        } // End of if ($recursionDepth > self::$maxRecursionDepthAllowed)     
     
        if ($recursionDepth == 0) {      
            // Store the original SimpleXmlElementObject sent by the caller.      
            // We will need it at the very end when we return from here for good.      
            $callerProvidedSimpleXmlElementObject = $simpleXmlElementObject;      
        } // End of if ($recursionDepth == 0)       
     
        if ($simpleXmlElementObject instanceof SimpleXMLElement) {      
            // Get a copy of the simpleXmlElementObject      
            $copyOfSimpleXmlElementObject = $simpleXmlElementObject;      
            // Get the object variables in the SimpleXmlElement object for us to iterate.      
            $simpleXmlElementObject = get_object_vars($simpleXmlElementObject);      
        } // End of if (get_class($simpleXmlElementObject) == "SimpleXMLElement")   
     
        // It needs to be an array of object variables.      
        if (is_array($simpleXmlElementObject)) {   
            // Initialize a result array.   
            $resultArray = array();      
            // Is the input array size 0? Then, we reached the rare CDATA text if any.      
            if (count($simpleXmlElementObject) <= 0) {      
                // Let us return the lonely CDATA. It could even be      
                // an empty element or just filled with whitespaces.      
                return (trim(strval($copyOfSimpleXmlElementObject)));      
            } // End of if (count($simpleXmlElementObject) <= 0)      
     
            // Let us walk through the child elements now.      
            foreach($simpleXmlElementObject as $key=>$value) {      
                // Check if we need to ignore the XML attributes.      
                // If yes, you can skip processing the XML attributes.      
                // Otherwise, add the XML attributes to the result array.      
                if(($ignoreXmlAttributes == true) && (is_string($key)) && ($key == "@attributes")) {      
                    continue;      
                } // End of if(($ignoreXmlAttributes == true) && ($key == "@attributes"))   
     
                // Let us recursively process the current XML element we just visited.      
                // Increase the recursion depth by one.      
                $recursionDepth++;       
                $resultArray[$key] = self::_processXml ($value, $ignoreXmlAttributes, $recursionDepth);      
     
                // Decrease the recursion depth by one.      
                $recursionDepth--;      
            } // End of foreach($simpleXmlElementObject as $key=>$value) {       
     
            if ($recursionDepth == 0) {      
                // That is it. We are heading to the exit now.      
                // Set the XML root element name as the root [top-level] key of      
                // the associative array that we are going to return to the original      
                // caller of this recursive function.      
                $tempArray = $resultArray;      
                $resultArray = array();      
                $resultArray[$callerProvidedSimpleXmlElementObject->getName()] = $tempArray;   
            } // End of if ($recursionDepth == 0)   
  
            return($resultArray);   
        } else {      
            // We are now looking at either the XML attribute text or      
            // the text between the XML tags.      
            return (trim(strval($simpleXmlElementObject)));      
        } // End of if (is_array($simpleXmlElementObject))      
    } // End of function _processXml. 
}

 

Am I missing something?

 

Delimiters perhaps?

 

 

[effigy]

<pre>
<?php
$data = 'Zend_Db_Table_Abstract';
echo preg_replace('/\b([A-Za-z]+(?:_[A-Za-z]+)+)\b/e', 'join("::", explode("_", "$1"))', $data);
?>
</pre>

 

Update:

 

...is there a way I can avoid this without knowing how many times $4 will match?

 

It will use the last match saved into the backreference each time it needs to be used. If a new match is found by capturing parentheses, the previously saved match is overwritten.

[nrg_alpha]

Is this what you are looking for?

 

$str = 'Zend_Db_Table_Abstract';
$str = preg_replace('#^([a-z]*)_([a-z]*_)+([^_]+)$#i', '$1::$3', $str);
echo $str';

 

output:

Zend::Abstract