<?php
/*
============================================================================================
Filename: 
---------
xml2json.php

Description: 
------------
This PHP class converts XML-based data into JSON formatted data. 
This program makes use of several open source PHP utility classes and functions.

License:
--------
This code is made available free of charge with the rights to use, copy, modify,
merge, publish and distribute. This Software shall be used for Good, not Evil.

First Created on:
-----------------
Oct/04/2006

Last Modified on:
-----------------
Oct/07/2006
============================================================================================
*/
require_once 'JSON.php';

// Internal program-specific Debug option.
define ("DEBUG", false);
// Maximum Recursion Depth that we can allow.
define ("MAX_RECURSION_DEPTH_ALLOWED", 25);
// An empty string
define ("EMPTY_STR", "");
// SimpleXMLElement object property name for attributes
define ("SIMPLE_XML_ELEMENT_OBJECT_PROPERTY_FOR_ATTRIBUTES", "@attributes");
// SimpleXMLElement object name.
define ("SIMPLE_XML_ELEMENT_PHP_CLASS", "SimpleXMLElement");

class xml2json {

	/*   
	=============================================================================
	Function name:
	---------------
	transformXmlStringToJson
	
	Function Parameters: 
	---------------------
	1) XML data string.
	
	Description:
	------------
	This function transforms the XML based String data into JSON format. If the input XML
	string is in table format, the resulting JSON output will also be in table format.
	Conversely, if the input XML string is in tree format, the resulting JSON output will
	also be in tree format.
	
	Function Return Value:
	----------------------
	1) If everything is successful, it returns a string containing JSON table/tree formatted data. 
	Otherwise, it returns an empty string.
		
	First Created on:
	-----------------
	Oct/04/2006
	
	Last Modified on:
	-----------------
	Oct/07/2006  	
	=============================================================================
	*/	
	public static function transformXmlStringToJson($xmlStringContents) {
		/*
		Get the SimpleXMLElement representation of the function input 
		parameter that contains XML string. Convert the XML string 
		contents to SimpleXMLElement type. SimpleXMLElement type is 
		nothing but an object that can be processed with normal property 
		selectors and (associative) array iterators.
		simplexml_load_string returns a SimpleXMLElement object which 
		contains an instance variable which itself is an associative array of 
		several SimpleXMLElement objects.	
		*/
		$simpleXmlElementObject = simplexml_load_string($xmlStringContents);	
		
		if ($simpleXmlElementObject == null) {
			return(EMPTY_STR);
		}
		
		$simpleXmlRootElementName = $simpleXmlElementObject->getName();
		// Uncomment this line to see the inner details of the SimpleXMLElement object.
		if (DEBUG) {
			// var_dump($simpleXmlRootElementName);
			// var_dump($simpleXmlElementObject);
		}	
	
		$jsonOutput = EMPTY_STR;		
		// Let us convert the XML structure into PHP array structure.
		$array1 = xml2json::convertSimpleXmlElementObjectIntoArray($simpleXmlElementObject);
		
		if (($array1 != null) && (sizeof($array1) > 0)) {		
			//create a new instance of Services_JSON
			$json = new Services_JSON();
			$jsonOutput = $json->encode($array1);
			
			if (DEBUG) {
				// var_dump($array1);
				// var_dump($jsonOutput);
			}	
		} // End of if (($array1 != null) && (sizeof($array1) > 0))
		
		return($jsonOutput);					
	} // End of function transformXmlStringToJson
		
	/*   
	=============================================================================
	Function name:
	---------------
	convertSimpleXmlElementObjectIntoArray
	
	Function Parameters: 
	---------------------
	1) Simple XML Element Object
	
	(The following function argument needs to be passed only when this function is 
	called recursively. It can be omitted when this function is called from another
	function.)
	2) Recursion Depth
	
	Description:
	------------
	This function accepts a SimpleXmlElementObject as a single argument. 
	This function converts the XML object into a PHP associative array. 
	If the input XML is in table format (i.e. non-nested), the resulting associative 
	array will also be in a table format. Conversely, if the input XML is in 
	tree (i.e. nested) format, this function will return an associative array 
	(tree/nested) representation of that XML.
	
	There are so many ways to turn an XML document into a PHP array. Out of all
	those options, the recursive logic here uses a method that is very nicely 
	documented by the PHP open source community in the SimpleXMLElement section of 
	the PHP manual available at www.php.net. Credit goes to all those kind 
	PHP (People Helping People!!!) souls.
	
	Function Return Value:
	----------------------
	1) If everything is successful, it returns an associate array containing 
	the data collected from the XML format. Otherwise, it returns null.
	
	Caution and Remarks:
	---------------------
	IT IS A RECURSIVE FUNCTION.
	
	First Created on:
	-----------------
	Oct/04/2006
	
	Last Modified on:
	-----------------
	June/01/2007  	
	=============================================================================
	*/		
	public static function convertSimpleXmlElementObjectIntoArray($simpleXmlElementObject, &$recursionDepth=0) {		
		// Keep an eye on how deeply we are involved in recursion.
		if ($recursionDepth > MAX_RECURSION_DEPTH_ALLOWED) {
			// Fatal error. Exit now.
			return(null);
		}

		if ($recursionDepth == 0) {
			if (get_class($simpleXmlElementObject) != SIMPLE_XML_ELEMENT_PHP_CLASS) {
				// If the external caller doesn't call this function initially  
				// with a SimpleXMLElement object, return now.				
				return(null);				
			} else {
				// 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 (@get_class($simpleXmlElementObject) == SIMPLE_XML_ELEMENT_PHP_CLASS) {
			// 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);
	   	}		
		  
       	// It needs to be an array of object variables.
   		if (is_array($simpleXmlElementObject)) {
   			// Initialize the 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 whitespaces.
   				return (trim(strval($copyOfsimpleXmlElementObject)));
   			}
   			
   			// Let us walk through the child elements now.
       		foreach($simpleXmlElementObject as $key=>$value) {
       			// When this block of code is commented, XML attributes will be
       			// added to the result array. 
       			// Uncomment the following block of code if XML attributes are  
       			// NOT required to be returned as part of the result array.       			
       			/*
  	     		if((is_string($key)) && ($key == SIMPLE_XML_ELEMENT_OBJECT_PROPERTY_FOR_ATTRIBUTES)) {
  	     			continue;
       			}
       			*/
       			// Let us recursively process the current element we just visited.
				// Increase the recursion depth by one.
				$recursionDepth++;	       			
           		$resultArray[$key] = xml2json::convertSimpleXmlElementObjectIntoArray($value, $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 caller of this
				// recursive function.
				$tempArray = $resultArray;
				$resultArray = array();
				$resultArray[$callerProvidedSimpleXmlElementObject->getName()] = $tempArray;
       		}
       		
       		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 else
	} // End of function convertSimpleXmlElementObjectIntoArray. 
	
} // End of class xml2json
?>