OOP: Error Calling Function on Object

[maxudaskin]

I get the error below when running my application. Any help in solving the error or improving the code is appreciated. Thank you in advance.

 

 

Fatal error: Call to a member function attributes() on a non-object in /**removed**/htdocs/include/classes/menu.php on line 42

 

Here is the offending code:

function elementsToArray(&$element)
{
$count = 0;

foreach ($element->attributes() as $key => $val) // Line 42
{
	$atts[$key] = $val;
}

foreach ($element->children() as $child) {
	$children[$count] = elementsToArray($child);
	$count++;
}

$arr = array(	'0' =>$element->name(),
				'1' => $element->value(),
				'2'=>$atts,
				'3'=>$children);

return $arr;
}

 

Here is the whole file, and below are the included files.

<?php
include_once($_SERVER['DOCUMENT_ROOT'] .'/include/classes/VFXP.inc.php');
class Menu
{
var $xmldoc;
var $rootelem;			
function __constructor()
{
	$this->xmldoc =& new VFXP_Document();
	$this->xmldoc->parseFromFile($_SERVER['DOCUMENT_ROOT'] .'/include/config/menu.xml');
	$this->rootelem =& $xmldoc->rootElement();
}

function reconstruct()
{
	$this->xmldoc =& new VFXP_Document();
	$this->xmldoc->parseFromFile($_SERVER['DOCUMENT_ROOT'] .'/include/config/menu.xml');
	$rootelem =& $this->xmldoc->rootElement();
}

function display($loggedIn)
{
	$this->reconstruct();
	$elements = ($loggedIn) ? $this->parseElements('isLogin') : $this->parseElements('noLogin');

	// Include Cascading Style Sheet and Javascript Functions
	echo '<link href="../styles.css" rel="stylesheet" type="text/css" />';
	echo '<script type="text/javascript" src="../classes/menuFunctions.js"></script>';


}

function parseElements($type)
{
	return $this->elementsToArray($this->rootelem);
}

function elementsToArray(&$element)
{
	$count = 0;

	foreach ($element->attributes() as $key => $val)
	{
		$atts[$key] = $val;
	}

	foreach ($element->children() as $child) {
		$children[$count] = elementsToArray($child);
		$count++;
	}

	$arr = array(	'0' =>$element->name(),
					'1' => $element->value(),
					'2'=>$atts,
					'3'=>$children);

	return $arr;
}
}
?>

 

VFXP.inc.php

<?php

// Package: VFXP - Very Fast XML Parser
// Author: Claudio Castelpietra
// Email: claudio@wopweb.com
// Web site: http://www.wopweb.com/
// License: "LGPL"
// Release history:
//   18/11/2005 - v.1.0 - First release.
//   24/01/2006 - v.1.1 - Some API added. Some php compatibility issues fixed.
// Description:
//   Very Fast XML Parser for PHP.
//   Completely standalone: no need for any PHP extension library.
//   Very fast processing, using iterative single-cycle parsing, instead of recursive or multi-step parsing.
//   Very useful for just loading simple application configuration parameters.
//   Strongly simplified and intuitive DOM API, with respect to the DOM Core Level 1
//   Works with PHP >= 3
//   Limitations in version 1.0:
//     XML version and encoding declaration tags are ignored.
//     DOCTYPE declaration tags are ignored.
// Notes:
//   I developed this class because the faster extension-independent PHP XML parser I've found took about 500 milliseconds to parse my configuration file, and this is not acceptable for a web page generation.
//   This class takes about 20 times less than the previous one.
//   Anyway, this it a PHP-interpreted class, so its performance cannot be compared to a C-compiled class. 
//


// The Document Class
//
class VFXP_Document {

// Parses XML from a file
//
function parseFromFile($filename) {

	$fp = fopen($filename, 'rb');
	$this->_docContentLength = filesize($filename);
	$this->_docContent = fread($fp, $this->_docContentLength);
	fclose($fp);

	$this->_parseContent();

	unset($this->_docContent);
}

// Parses XML from a string
//
function parseFromString($content) {
	$this->_docContent = $content;

	$this->_parseContent();

	unset($this->_docContent);
}

// Returns a reference to the root Element
//
function & rootElement() {
	return $this->_docRoot;
}


// Private variables and methods:

var $_docContent; // The XML content
var $_docContentLength;
var $_docRoot; // Reference to the root element

// Iterative method for fast XML parsing
//
function _parseContent() {

	// Removing some tags we don't handle
	$this->_docContent = eregi_replace('<\?xml [^>]+\?>|<!doctype [^\\[>]+(\\[[^]]*\\])?>', '', $this->_docContent);

	$parseStack = array();
	$stacklen = 0;
	$currpos = 0;

	while (true) {

		// let's extract the next tag
		$tag = new VFXP_Tag();

		// find the begin of the tag
		$tag->pos_start = strpos($this->_docContent, '<', $currpos);
		if ($tag->pos_start === FALSE) {
			die("VFXP - Error: XML tag not found.");
		}

		// check and skip comments
		if (substr($this->_docContent, $tag->pos_start, 4) == '<!--') {
			// we found a comment, let's look for its end
			$tag->pos_end = strpos($this->_docContent, '-->', $tag->pos_start + 4) + 2;
			if ($tag->pos_end === FALSE) {
				die("VFXP - Error: incomplete XML comment");
			}
			// skipping comment tag
			$currpos = $tag->pos_end + 1;
			continue;
		}

		// check and skip CDATA sections
		if (substr($this->_docContent, $tag->pos_start, 9) == '<![CDATA[') {
			// we found a cdata section, let's look for its end
			$tag->pos_end = strpos($this->_docContent, ']]>', $tag->pos_start + 9) + 2;
			if ($tag->pos_end === FALSE) {
				die("VFXP - Error: incomplete XML CDATA section");
			}
			// skipping cdata section
			$currpos = $tag->pos_end + 1;
			continue;
		}

		// find the end of the tag
		$tag->pos_end = strpos($this->_docContent, '>', $tag->pos_start);
		if ($tag->pos_end === FALSE) {
			die("VFXP - Error: incomplete XML tag");
		}
		$currpos = $tag->pos_end + 1;


		// We have the tag. Let's check its type.
		if (substr($this->_docContent, $tag->pos_start + 1, 1) == '/') {
			$tag->is_opening = false;
			$tag->is_closing = true;
			$tag->name = substr($this->_docContent, $tag->pos_start + 2, $tag->pos_end - $tag->pos_start - 2);
			// $tag->attributes = array(); // will not be used
		} else {
			$tag->is_opening = true;
			if (substr($this->_docContent, $tag->pos_end - 1, 1) == '/') {
				$tag->is_closing = true;
				$tag->name = substr($this->_docContent, $tag->pos_start + 1, $tag->pos_end - $tag->pos_start - 2);
			} else {
				$tag->is_closing = false;
				$tag->name = substr($this->_docContent, $tag->pos_start + 1, $tag->pos_end - $tag->pos_start - 1);
			}
			// Tag attributes parsing
			ereg("^([^ \n\r\t/]+)([ \n\r\t/](.*))?$", $tag->name, $regs);
			$tag->name = $regs[1];

			$attr_string = $regs[3];

			$tag->attributes = array();
			while ($attr_string != '') {
				// magic regular expression for extracting the attributes one at a time
				if (ereg("[ \n\r\t]*([^ \n\r\t=]+)(=(\"(\"|([^\"]*[^\\])\")|[^ \n\r\t\"][^ \n\r\t]*))?([ \n\r\t].*)?$", $attr_string, $regs)) {
					if ($regs[5] != '') {
						$tag->attributes[$regs[1]] = $regs[5];
					} else {
						$tag->attributes[$regs[1]] = $regs[3];
					}
					$attr_string = $regs[6];
				} else {
					break;
				}
			}
		}

		// Let's check the tag against the parsing stack
		if ($tag->is_opening) {

			// building the element corresponding to the found opening tag
			$elem =& new VFXP_Element();
			$elem->_name = $tag->name;
			$elem->_value = NULL;
			$elem->_attributes = $tag->attributes;
			$elem->_subelements = array();

			if ($stacklen == 0) {
				// This is the root element
				$this->_docRoot =& $elem;
			}

			$tag->elem_ref =& $elem; // saving a reference to the element into the opening tag

			array_push($parseStack, $tag); // pushing the opening tag onto the parsing stack
			++$stacklen;

		}

		if ($tag->is_closing) {

			--$stacklen;
			$tag_top = array_pop($parseStack);

			if ($tag_top->name != $tag->name) {
				print("VFXP - Closing tag not matching. Tag:".$tag->name." Pos:".$tag->pos_start . "<br>\nParse Stack:<br>\n");
				print_r($parseStack);
				die();
			}

			// element complete
			// estraction of the element value - only if non self-closing or if without subelements
			if (!$tag->is_opening && count($tag_top->elem_ref->_subelements) == 0) {
				$tag_top->elem_ref->_value = substr($this->_docContent, $tag_top->pos_end + 1, $tag->pos_start - $tag_top->pos_end - 1);
				// processing CDATA sections
				if (substr($tag_top->elem_ref->_value, 0, 9) == '<![CDATA[') {
					$tag_top->elem_ref->_value = substr($tag_top->elem_ref->_value, 9, -3);
				}
			}

			// let's add the element to the list of the subelements of the parent element
			if ($stacklen > 0) {
				$parseStack[$stacklen-1]->elem_ref->_subelements[] =& $tag_top->elem_ref;
				//print($tag_top->elem_ref->name . ' child of ' . $parseStack[count($parseStack)-1]->elem_ref->name . "<br>\n");
			} else {
				// stack exausted - elaboration finished
				break;
			}
		}

	}

}


}


// The Document Element
//
class VFXP_Element {

// Returns the name of the element
//
function name() {
	return $this->_name;
}

// Returns the value of the element
//
function value() {
	return $this->_value;
}

// Returns true if there is at least one child with the given name
//
function hasChildren($elementname = NULL) {
	if ($elementname) {
		return (firstChild($elementname) != NULL);
	} else {
		return isset($this->_subelements[0]);
	}
}

// Returns a reference to the first element with the given name, or NULL if not found.
//
function & firstChild($elementname = NULL) {
	if ($elementname) {
		for ($pos = 0; $pos < count($this->_subelements); ++$pos) {
			if ($this->_subelements[$pos]->_name == $elementname) {
				return $this->_subelements[$pos];
			}
		}
	} else {
		if (isset($this->_subelements[0])) {
			return $this->_subelements[0];
		}
	}
	$tmp0 = NULL;
	$tmp =& $tmp0;
	return $tmp;
}

// Returns the value of the first child with the given name, or NULL if not found.
//
function childValue($elementname = NULL) {
	$elem =& $this->firstChild($elementname);
	if ($elem) {
		return $elem->_value;
	} else {
		return NULL;
	}
}

// Returns an array of references to the subelements having a given name.
//
function children($elementname = NULL) {
	if ($elementname) {
		$tmparr = array();
		for ($pos = 0; $pos < count($this->_subelements); ++$pos) {
			if ($this->_subelements[$pos]->_name == $elementname) {
				$tmparr[] =& $this->_subelements[$pos];
			}
		}
		return $tmparr;
	} else {
		return $this->_subelements;
	}
}

// Returns an associative array of couples (child-name => child-value)
//
function childrenAssociative() {
	$tmparr = array();
	for ($pos = 0; $pos < count($this->_subelements); ++$pos) {
		$tmparr[$this->_subelements[$pos]->_name] = $this->_subelements[$pos]->_value;
	}
	return $tmparr;
}

// Returns a reference to the array-map of the attribute-name=>attribute-value pairs
//
function & attributes() {
	return $this->_attributes;
}

// Returns the value of the given attribute, or NULL if not found
//
function attributeValue($attributename) {
	if (isset($this->_attributes[$attributename])) {
		return $this->_attributes[$attributename];
	} else {
		return NULL;
	}
}


var $_name;
var $_value; // string value, or NULL if self-closing tag of if has children
var $_attributes; // attributes array-map
var $_subelements; // subelements array

}


// Temporary tag objects for parsing
//
class VFXP_Tag {
var $pos_start; // first tag character
var $pos_end; // last tag character
var $is_opening;
var $is_closing;
var $name;
var $attributes; // array-map of the tag attributes
var $elem_ref; // reference to the corresponding element
}


?>

[oni-kun]

Apparently on line 42 there is a non-object.

[maxudaskin]

Apparently on line 42 there is a non-object.

 

The thing is, if you see, it is referring to the variable $element. $element has it's value (a reference to $rootelem) passed down. I had tested this outside of a class and it worked fine. Here is that code:

<?php

require_once($_SERVER['DOCUMENT_ROOT'] .'/include/classes/VFXP.inc.php');

$xmldoc = new VFXP_Document();
$xmldoc->parseFromFile($_SERVER['DOCUMENT_ROOT'] .'/include/config/menu.xml');

$rootelem =& $xmldoc->rootElement();


function spaces($n) {
	$out = '';
	for ($p = 0; $p < $n; ++$p) {
		$out .= ' ';
	}
	return $out;
}
function recursive_print(&$element, $level = 0) {
	$out = '';
	$out .= spaces($level* . 'Begin Element' . "\n";
	$out .= spaces($level* . '-------Name: ' . $element->name() . "\n";
	$out .= spaces($level* . '------Value: ' . $element->value() . "\n";
	$out .= spaces($level* . '-Attributes: ' . "\n";
	foreach ($element->attributes() as $key => $val) {
		$out .= spaces($level*8+ . "[{$key}] => $val" . "\n";
	}
	$out .= spaces($level* . '---Children: ' . "\n";
	foreach ($element->children() as $child) {
		$out .= recursive_print($child, $level + 1);
	}
	$out .= spaces($level* . 'End Element' . "\n";
	return $out;
}

function elementsToArray(&$element)
{
	$count = 0;

	foreach ($element->attributes() as $key => $val)
	{
		$atts[$key] = $val;
	}

	foreach ($element->children() as $child) {
		$children[$count] = elementsToArray($child);
		$count++;
	}

	$arr = array(	'0' =>$element->name(),
					'1' => $element->value(),
					'2'=>$atts,
					'3'=>$children);

	return $arr;
}

?>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>VFXP Test</title>
</head>

<body>

<pre>
<?php
//print_r($rootelem);
$arr = elementsToArray($rootelem);
print_r ($arr);
?>
</pre>

</body>
</html>

 

[KevinM1]

Some thoughts/observations/suggestions/questions:

 

1. Are you sure that $element is, itself, an object?

 

2. In your class, you have parseElements($type), yet you never do anything with $type.

 

3. Since your object already contains $rootelem, you don't need to pass it into the argument list for elementsToArray.  So, do something like:

 

function parseElements($type)
{
   // do something with $type

   return $this->elementsToArray();
}

function elementsToArray()
{
   // if $this->rootelem exists, run the function, else, error
}

[maxudaskin]

2. In your class, you have parseElements($type), yet you never do anything with $type.

 

The class functions are not complete yet. I ran into this error and stopped coding to problem solve.

 

I took your advice in #3, but I'm still getting this error :/

[maxudaskin]

I made the suspect variables local to the function parseElements which has fixed the issue. Thank you all for your time and help.