OOP: Error Calling Function on Object

maxudaskin · April 5, 2010

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 · April 5, 2010

Apparently on line 42 there is a non-object.

maxudaskin · April 5, 2010

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 · April 5, 2010

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 · April 5, 2010

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 · April 5, 2010

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

Sign In

OOP: Error Calling Function on Object

Recommended Posts

maxudaskin

Link to comment

Share on other sites

oni-kun

Link to comment

Share on other sites

maxudaskin

Link to comment

Share on other sites

KevinM1

Link to comment

Share on other sites

maxudaskin

Link to comment

Share on other sites

maxudaskin

Link to comment

Share on other sites

Join the conversation

Browse

Activity

Important Information