references to objects

[Anon]

hi,

i have a problem with a recursive function call and i think the reason is that i should work with references. i tried it in various ways, but couldn't find a solution.

i wrote a script, that parses a xml-document and converts (should do it) it in a tree of xml-elements.

this is the code:

<?
class CTreeElement
{
var $m_szName;
var $m_arSubElems;
var $m_parent;

// constructor
function CTreeElement($szName, $parent)
{
$this->m_szName = $szName;
$this->m_arSubElems = array();
$this->m_parent = $parent;
$this->test = 'init val';
}

function addSubElem($sub)
{
array_push($this->m_arSubElems, $sub);
}
}

$g_iDepth = 0;
$g_xmlTree = new CTreeElement('root', null);
$g_curElem = $g_xmlTree;

$xml_data = '<?xml version="1.0"?>
<name1>
<name1_1>
<name1_1_1>
</name1_1_1>

<name1_1_2>
</name1_1_2>

</name1_1>

<name1_2>
<name1_2_1>
</name1_2_1>

<name1_2_2>
</name1_2_2>

</name1_2>
</name1>';

function startElement($parser, $name, $attrs)
{
global $g_iDepth;
global $g_curElem;

$newElem = new CTreeElement($name, $g_curElem);

$g_curElem->addSubElem($newElem);

$g_curElem = $newElem;

$g_iDepth++;
}

function endElement($parser, $name)
{
global $g_iDepth;
global $g_curElem;

$g_curElem = $g_curElem->m_parent;

print('endElement: ' . $g_curElem->m_szName . ': ' . count($g_curElem->m_arSubElems) . '<br>');

$g_iDepth--;
}

$xml_parser = xml_parser_create();
// use case-folding so we are sure to find the tag in $map_array
xml_parser_set_option($xml_parser, XML_OPTION_CASE_FOLDING, true);
xml_set_element_handler($xml_parser, "startElement", "endElement");

if (!xml_parse($xml_parser, $xml_data))
{
die(sprintf("XML error: %s at line %d",
xml_error_string(xml_get_error_code($xml_parser)),
xml_get_current_line_number($xml_parser)));
}

xml_parser_free($xml_parser);
?>

the output is:

endElement: NAME1_1: 0
endElement: NAME1_1: 0
endElement: NAME1: 0
endElement: NAME1_2: 0
endElement: NAME1_2: 0
endElement: NAME1: 0
endElement: root: 0

my interpretation is that $g_curElem = $newElem; assigns to $g_curElem a copy of $newElem and i do the addSubElem() call to this copy of the new element.

which is the right way?

please help

matze

[simon_belak]

$g_curElem = &$newElem; should do the trick

[Anon]

hello simon,

thanX for your help, but it doesn't work

i tried it too, with the following result:

endElement: : 0

Fatal error: Call to a member function on a non-object

i thought ok, i have to be more consequent and changed in endElement() $g_curElem = $g_curElem->m_parent to $g_curElem = &$g_curElem->m_parent.
output:

endElement: : 0
endElement: : 0
endElement: : 0
endElement: : 0
endElement: : 0
endElement: : 0
endElement: : 0

when i inspect $g_curElem in startElement() i see that it's always set to the root object and all subelements were added to this root object.

changing the line $g_curElem = $g_xmlTree to $g_curElem = &$g_xmlTree has the same effect

what's going on with php-references? i know c, perl and java, but can't understand the concept of php

8-(

matze

[Anon]

with the help of the following article http://www.phpbuilder.com/forum/read.php3?num=1&id=107773&loc=0&thread=107759 it works that the childs store their parent object. but i still have the problem, that $g_curElem always points to $g_xmlTree. i set it to the new created child in startElement, but php forgets this when entering this function the next time.

matze

[Anon]

Thanks for the reference to the article! It helped me too!