The XMLReader class

(PHP 5 >= 5.1.0, PHP 7)

简介

The XMLReader extension is an XML Pull parser. The reader acts as a cursor going forward on the document stream and stopping at each node on the way.

类摘要

XMLReader {
/* 常量 */
const int NONE = 0 ;
const int ELEMENT = 1 ;
const int ATTRIBUTE = 2 ;
const int TEXT = 3 ;
const int CDATA = 4 ;
const int ENTITY_REF = 5 ;
const int ENTITY = 6 ;
const int PI = 7 ;
const int COMMENT = 8 ;
const int DOC = 9 ;
const int DOC_TYPE = 10 ;
const int DOC_FRAGMENT = 11 ;
const int NOTATION = 12 ;
const int WHITESPACE = 13 ;
const int SIGNIFICANT_WHITESPACE = 14 ;
const int END_ELEMENT = 15 ;
const int END_ENTITY = 16 ;
const int XML_DECLARATION = 17 ;
const int LOADDTD = 1 ;
const int DEFAULTATTRS = 2 ;
const int VALIDATE = 3 ;
const int SUBST_ENTITIES = 4 ;
/* 属性 */
public readonly int $attributeCount ;
public readonly string $baseURI ;
public readonly int $depth ;
public readonly bool $hasAttributes ;
public readonly bool $hasValue ;
public readonly bool $isDefault ;
public readonly bool $isEmptyElement ;
public readonly string $localName ;
public readonly string $name ;
public readonly string $namespaceURI ;
public readonly int $nodeType ;
public readonly string $prefix ;
public readonly string $value ;
public readonly string $xmlLang ;
/* 方法 */
public bool close ( void )
public DOMNode expand ([ DOMNode $basenode ] )
public string getAttribute ( string $name )
public string getAttributeNo ( int $index )
public string getAttributeNs ( string $localName , string $namespaceURI )
public bool getParserProperty ( int $property )
public bool isValid ( void )
public string lookupNamespace ( string $prefix )
public bool moveToAttribute ( string $name )
public bool moveToAttributeNo ( int $index )
public bool moveToAttributeNs ( string $localName , string $namespaceURI )
public bool moveToElement ( void )
public bool moveToFirstAttribute ( void )
public bool moveToNextAttribute ( void )
public bool next ([ string $localname ] )
public bool open ( string $URI [, string $encoding [, int $options = 0 ]] )
public bool read ( void )
public string readInnerXML ( void )
public string readOuterXML ( void )
public string readString ( void )
public bool setParserProperty ( int $property , bool $value )
public bool setRelaxNGSchema ( string $filename )
public bool setRelaxNGSchemaSource ( string $source )
public bool setSchema ( string $filename )
public bool xml ( string $source [, string $encoding [, int $options = 0 ]] )
}

属性

attributeCount

The number of attributes on the node

baseURI

The base URI of the node

depth

Depth of the node in the tree, starting at 0

hasAttributes

Indicates if node has attributes

hasValue

Indicates if node has a text value

isDefault

Indicates if attribute is defaulted from DTD

isEmptyElement

Indicates if node is an empty element tag

localName

The local name of the node

name

The qualified name of the node

namespaceURI

The URI of the namespace associated with the node

nodeType

The node type for the node

prefix

The prefix of the namespace associated with the node

value

The text value of the node

xmlLang

The xml:lang scope which the node resides

预定义常量

XMLReader Node Types

XMLReader::NONE

No node type

XMLReader::ELEMENT

Start element

XMLReader::ATTRIBUTE

Attribute node

XMLReader::TEXT

Text node

XMLReader::CDATA

CDATA node

XMLReader::ENTITY_REF

Entity Reference node

XMLReader::ENTITY

Entity Declaration node

XMLReader::PI

Processing Instruction node

XMLReader::COMMENT

Comment node

XMLReader::DOC

Document node

XMLReader::DOC_TYPE

Document Type node

XMLReader::DOC_FRAGMENT

Document Fragment node

XMLReader::NOTATION

Notation node

XMLReader::WHITESPACE

Whitespace node

XMLReader::SIGNIFICANT_WHITESPACE

Significant Whitespace node

XMLReader::END_ELEMENT

End Element

XMLReader::END_ENTITY

End Entity

XMLReader::XML_DECLARATION

XML Declaration node

XMLReader Parser Options

XMLReader::LOADDTD

Load DTD but do not validate

XMLReader::DEFAULTATTRS

Load DTD and default attributes but do not validate

XMLReader::VALIDATE

Load DTD and validate while parsing

XMLReader::SUBST_ENTITIES

Substitute entities and expand references

Table of Contents

User Contributed Notes

eef dot vreeland at gmail dot com 11-Aug-2017 02:43
Please discard my previous note; I pressed 'Add Note' too quickly

About (non-)self-closing tags:

 A) <tag></tag>
    $xmlRdr->isEmptyElement => false
    $xmlRdr->hasValue       => false
    $xmlRdr->value          => ''
    $xmlRdr->hasAttributes  => false
 
 B) <tag />
    $xmlRdr->isEmptyElement => true
    $xmlRdr->hasValue       => false
    $xmlRdr->value          => ''
    $xmlRdr->hasAttributes  => false
 
 C) <tag attribute="value"></tag>
    $xmlRdr->isEmptyElement => false
    $xmlRdr->hasValue       => false
    $xmlRdr->value          => ''
    $xmlRdr->hasAttributes  => true
 
 D) <tag attribute="value" />
    $xmlRdr->isEmptyElement => true
    $xmlRdr->hasValue       => false
    $xmlRdr->value          => ''
    $xmlRdr->hasAttributes  => true
 
... and always use the '===' operator when testing properties
eef dot vreeland at gmail dot com 11-Aug-2017 02:08
Note that when:

A) <tag></tag>
   $xmlRdr->isEmptyElement => false
   $xmlRdr->hasValue       => true
   $xmlRdr->value          => ''
   $xmlRdr->hasAttributes  => false

B) <tag />
   $xmlRdr->isEmptyElement => true
   $xmlRdr->hasValue       => false
   $xmlRdr->value          => ''
   $xmlRdr->hasAttributes  => false

C) <tag attribute="value"></tag>
   $xmlRdr->isEmptyElement => false
   $xmlRdr->hasValue       => false
   $xmlRdr->value          => ''
   $xmlRdr->hasAttributes  => true

D) <tag attribute="value" />
   $xmlRdr->isEmptyElement => true
   $xmlRdr->hasValue       => false
   $xmlRdr->value          => ''
   $xmlRdr->hasAttributes  => true
Sean Colin Ruiz 08-Jan-2017 12:11
As japos mentioned. Take care how you use isEmptyElement. After you are done looping through the attributes: isEmptyElement will be false.  You can use moveToElement() to move the cursor back to the element and then you can use isEmptyElement like normal again.
dkrnl at yandex dot ru 04-Oct-2013 01:10
Wrapper XMLReader class, for simple SAX-reading huge xml:
https://github.com/dkrnl/SimpleXMLReader

Usage example: http://github.com/dkrnl/SimpleXMLReader/blob/master/examples/example1.php

<?php

/**
 * Simple XML Reader
 *
 * @license Public Domain
 * @author Dmitry Pyatkov(aka dkrnl) <dkrnl@yandex.ru>
 * @url http://github.com/dkrnl/SimpleXMLReader
 */
class SimpleXMLReader extends XMLReader
{

    /**
     * Callbacks
     *
     * @var array
     */
    protected $callback = array();

    /**
     * Add node callback
     *
     * @param  string   $name
     * @param  callback $callback
     * @param  integer  $nodeType
     * @return SimpleXMLReader
     */
    public function registerCallback($name, $callback, $nodeType = XMLREADER::ELEMENT)
    {
        if (isset($this->callback[$nodeType][$name])) {
            throw new Exception("Already exists callback $name($nodeType).");
        }
        if (!is_callable($callback)) {
            throw new Exception("Already exists parser callback $name($nodeType).");
        }
        $this->callback[$nodeType][$name] = $callback;
        return $this;
    }

    /**
     * Remove node callback
     *
     * @param  string  $name
     * @param  integer $nodeType
     * @return SimpleXMLReader
     */
    public function unRegisterCallback($name, $nodeType = XMLREADER::ELEMENT)
    {
        if (!isset($this->callback[$nodeType][$name])) {
            throw new Exception("Unknow parser callback $name($nodeType).");
        }
        unset($this->callback[$nodeType][$name]);
        return $this;
    }

    /**
     * Run parser
     *
     * @return void
     */
    public function parse()
    {
        if (empty($this->callback)) {
            throw new Exception("Empty parser callback.");
        }
        $continue = true;
        while ($continue && $this->read()) {
            if (isset($this->callback[$this->nodeType][$this->name])) {
                $continue = call_user_func($this->callback[$this->nodeType][$this->name], $this);
            }
        }
    }

    /**
     * Run XPath query on current node
     *
     * @param  string $path
     * @param  string $version
     * @param  string $encoding
     * @return array(SimpleXMLElement)
     */
    public function expandXpath($path, $version = "1.0", $encoding = "UTF-8")
    {
        return $this->expandSimpleXml($version, $encoding)->xpath($path);
    }

    /**
     * Expand current node to string
     *
     * @param  string $version
     * @param  string $encoding
     * @return SimpleXMLElement
     */
    public function expandString($version = "1.0", $encoding = "UTF-8")
    {
        return $this->expandSimpleXml($version, $encoding)->asXML();
    }

    /**
     * Expand current node to SimpleXMLElement
     *
     * @param  string $version
     * @param  string $encoding
     * @param  string $className
     * @return SimpleXMLElement
     */
    public function expandSimpleXml($version = "1.0", $encoding = "UTF-8", $className = null)
    {
        $element = $this->expand();
        $document = new DomDocument($version, $encoding);
        $node = $document->importNode($element, true);
        $document->appendChild($node);
        return simplexml_import_dom($node, $className);
    }

    /**
     * Expand current node to DomDocument
     *
     * @param  string $version
     * @param  string $encoding
     * @return DomDocument
     */
    public function expandDomDocument($version = "1.0", $encoding = "UTF-8")
    {
        $element = $this->expand();
        $document = new DomDocument($version, $encoding);
        $node = $document->importNode($element, true);
        $document->appendChild($node);
        return $document;
    }

}
?>
kula_shakerz 03-Apr-2013 11:27
Found this in the IXmlReader docs at msdn but it's also valid for XMLReader in PHP.

You should save the value of $isEmptyElement before processing attributes, or call moveToElement to make $isEmptyElement valid after processing attributes.

$isEmptyElement returns FALSE when XMLReader is positioned on an attribute node, even if attribute's parent element is empty.
Mike De Smet 26-Sep-2012 01:35
For those of you getting xml files that do not contain duplicate elements (in the same element), the following converter converts to arrays with key/value mapping (thus overwriting duplicate elements!):

Note this is untested with attributes although I built in support.

<?php
    function xml2assoc($xml, array &$target = array()) {
        while ($xml->read()) {
            switch ($xml->nodeType) {
                case XMLReader::END_ELEMENT:
                    return $target;
                case XMLReader::ELEMENT:
                    $name = $xml->name;
                    $target[$name] = $xml->hasAttributes ? array() : '';
                    if (!$xml->isEmptyElement) {
                        $target[$name] = array();
                        xml2assoc($xml, $target[$name]);
                    }

                    if ($xml->hasAttributes)
                        while($xml->moveToNextAttribute())
                            $target[$name]['@'.$xml->name] = $xml->value;
                    break;
                case XMLReader::TEXT:
                case XMLReader::CDATA:
                    $target = $xml->value;
            }
        }
        return $target;
    }
?>
casella dot email at google dot mail dot com 23-Sep-2012 12:59
To verify that all nodes are read without error/warning you can use this code:
<?php
$endofxml = false;
$xml_url = "example.xml";
$reader = new XMLReader();
if(!$reader->open($xml_url)){
    print "Error to open XML: $xml_url\n";
} else {
    while ($reader->read()) {
        $firstnode = (!isset($firstnode)) ? $reader->name : $firstnode;
/*
DO SOMETHING
*/
        if ($reader->nodeType == XMLReader::END_ELEMENT && $reader->name == $firstnode) {   
            $endofxml = true;
        }
    }
}
if($endofxml) {
    print "no error found";
} else {
    print "error found";
}
?>

This code is useful to trap $reader->read() error/warning.
lee8oi at gmail dot com 21-Mar-2012 10:54
Sometimes you have an unusual URL that doesn't actually point to an xml file but still returns xml as output (Like the Battlefield Heroes generated syndication urls). Using get_file_contents(url) you can retrieve the xml data from these urls and pass it as a variable for processing as an XML String.

Unfortunately simpleXML or xml DOM cannot process all xml strings. Some have error boxes added to the end of them (such as Battlefield Heroes syndicated news). These boxes cause an end of file sort of error and closes out the script. XMLReader grabs data from these strings without error.
japos dot trash at googlemail dot com 09-Oct-2010 11:17
Take care about how to use XMLReader::$isElementEmpty. I don't know if it is a bug or not, but $isElementEmpty is set for the current context and NOT just for the element. If you move your cursor to an attribute, $isElementEmpty will ALWAYS be false.

<?php
 $xml = new XMLReader();
 $xml->XML('<tag attr="value" />');
 $xml->read();
 var_dump($xml->isEmptyElement);
 $xml->moveToNextAttribute();
 var_dump($xml->isEmptyElement);
?>

will output

(bool) true
(bool) false

So be sure to store $isEmptyElement before moving the cursor.
jart (at) mail.ru 23-Sep-2010 03:59
Guys, I hope this example will help
you can erase prints showing the process-
and it will be a piece of nice code.

<?php
function xml2assoc($xml, $name)
{
    print "<ul>";

    $tree = null;
    print("I'm inside " . $name . "<br>");
   
    while($xml->read())
    {
        if($xml->nodeType == XMLReader::END_ELEMENT)
        {
            print "</ul>";
            return $tree;
        }
       
        else if($xml->nodeType == XMLReader::ELEMENT)
        {
            $node = array();
           
            print("Adding " . $xml->name ."<br>");
            $node['tag'] = $xml->name;

            if($xml->hasAttributes)
            {
                $attributes = array();
                while($xml->moveToNextAttribute())
                {
                    print("Adding attr " . $xml->name ." = " . $xml->value . "<br>");
                    $attributes[$xml->name] = $xml->value;
                }
                $node['attr'] = $attributes;
            }
           
            if(!$xml->isEmptyElement)
            {
                $childs = xml2assoc($xml, $node['tag']);
                $node['childs'] = $childs;
            }
           
            print($node['tag'] . " added <br>");
            $tree[] = $node;
        }
       
        else if($xml->nodeType == XMLReader::TEXT)
        {
            $node = array();
            $node['text'] = $xml->value;
            $tree[] = $node;
            print "text added = " . $node['text'] . "<br>";
        }
    }
   
    print "returning " . count($tree) . " childs<br>";
    print "</ul>";
   
    return $tree;
}

echo "<PRE>";

$xml = new XMLReader();
$xml->open('test.xml');
$assoc = xml2assoc($xml, "root");
$xml->close();

print_r($assoc);
echo "</PRE>";

?>

It reads this xml:

<test>
    <hallo volume="loud"> me <br/> lala </hallo>
    <hallo> me </hallo>
</test>
jnettles at inccrra dot org 02-Oct-2009 06:51
Just in case someone is confused, if you're wanting to simply pass a string of XML instead of an entire file, you would do this.

<?php
$foo = new XMLReader();
$foo->xml($STRING);
?>

.... where $STRING holds your XML. You cannot pass it like $foo = $STRING or $foo->xml = $STRING.
james dot ellis at example dot com 26-Mar-2009 12:16
The "XML2Assoc" functions noted here should be used with caution... basically they are duplicating the functionality already present in SimpleXML. They may work but they won't scale.

Their are two main uses cases for parsing XML, each suited to either XMLReader or SimpleXML.

1. SimpleXML is an excellent tool for easy access to an XML document tree using native PHP data types. It starts to flounder with massive (> 50M or so) XML documents, as it reads the entire document into memory before it can be processed. SimpleXML will just laugh at you then die when your server runs out of memory (or it will cause a load spike).

2. Aside from the reasoning behind massive XML documents, if you have to deal with massive XML documents, use XMLReader to process them. Don't try and gather an entire XML document into a PHP data structure using XMLReader and a PHP xml2assoc() function, you are reinventing the SimpleXML wheel.
When parsing massive XML documents using XMLReader, gather the data you need to perform an operation then perform it before skipping to the next node. Do not build massive data structures from a massive XML document, your server (and it's admins) will not like you.
PxL 23-Jan-2009 12:36
A basic parser

<?php
function xml2assoc($xml) {
    $arr = array();
    if (!preg_match_all('|\<\s*?(\w+).*?\>(.*)\<\/\s*\\1.*?\>|s', $xml, $m)) return $xml;
    if (is_array($m[1]))
        for ($i = 0;$i < sizeof($m[1]); $i++) $arr[$m[1][$i]] = xml2assoc($m[2][$i]);
    else $arr[$m[1]] = xml2assoc($m[2]);

    return $arr;
}
?>
boukeversteegh at gmail dot com 18-Jan-2009 11:06
XML to ASSOCIATIVE ARRAY

Improved algorithm based on Sergey Aikinkulov's. The problem was that it would overwrite nodes if they had the same tag name. Because of that <a><b/><b/><a> would be read as if <a><b/><a/>. This algorithm handles it better and outputs an easy to understand array:

<?php
function xml2assoc($xml) {
    $tree = null;
    while($xml->read())
        switch ($xml->nodeType) {
            case XMLReader::END_ELEMENT: return $tree;
            case XMLReader::ELEMENT:
                $node = array('tag' => $xml->name, 'value' => $xml->isEmptyElement ? '' : xml2assoc($xml));
                if($xml->hasAttributes)
                    while($xml->moveToNextAttribute())
                        $node['attributes'][$xml->name] = $xml->value;
                $tree[] = $node;
            break;
            case XMLReader::TEXT:
            case XMLReader::CDATA:
                $tree .= $xml->value;
        }
    return $tree;
}

?>

Usage:

myxml.xml:
------
<PERSON>
    <NAME>John</NAME>
    <PHONE type="home">555-555-555</PHONE>
</PERSON>
----

<?
    $xml = new XMLReader();
    $xml->open('myxml.xml');
    $assoc = xml2assoc($xml);
    $xml->close();
    print_r($assoc);
?>

Outputs:
Array
(
    [0] => Array
        (
            [tag] => PERSON
            [value] => Array
                (
                    [0] => Array
                        (
                            [tag] => NAME
                            [value] => John
                        )

                    [1] => Array
                        (
                            [tag] => PHONE
                            [value] => 555-555-555
                            [attributes] => Array
                                (
                                    [type] => home
                                )

                        )

                )

        )

)

For reasons that have to do with recursion, it returns an array with the ROOT xml node as the first childNode, rather than to return only the ROOT node.
andrei_antal at yahoo dot com 08-Jan-2009 05:25
<?php
//Pull certain elements
 $reader = new XMLReader();
  $reader->open($xmlfile);
while ($reader->read()) {
 switch ($reader->nodeType) {
   case (XMLREADER::ELEMENT):

if ($reader->name == "Code")
     {
       $reader->read();
       $code = trim($reader->value);
       echo "$code\n";
       break;
     }

 if ($reader->name == "Name")
     {
       $reader->read();
       $customername = trim( $reader->value );
       echo "$name\n";
       break;
     }

 if ($reader->name == "Camp")
    {
      $camp = trim($reader->getAttribute("ID"));
       echo "$camp\n";
      break;
    }
  }
}
?>
godseth at o2 dot pl 28-Nov-2008 11:34
Thanks rein_baarsma33 AT hotmail DOT com for bugfixes.

This is my new child of XML parsing method  based on my and yours modification.

XML2ASSOC Is a complete solution for parsing ordinary XML

<?php
/**
 * XML2Assoc Class to creating
 * PHP Assoc Array from XML File
 *
 * @author godseth (AT) o2.pl & rein_baarsma33 (AT) hotmail.com (Bugfixes in parseXml Method)
 * @uses XMLReader
 *
 */

class Xml2Assoc {

    /**
     * Optimization Enabled / Disabled
     *
     * @var bool
     */
    protected $bOptimize = false;

    /**
     * Method for loading XML Data from String
     *
     * @param string $sXml
     * @param bool $bOptimize
     */

    public function parseString( $sXml , $bOptimize = false) {
        $oXml = new XMLReader();
        $this -> bOptimize = (bool) $bOptimize;
        try {

            // Set String Containing XML data
            $oXml->XML($sXml);

            // Parse Xml and return result
            return $this->parseXml($oXml);

        } catch (Exception $e) {
            echo $e->getMessage();
        }
    }

    /**
     * Method for loading Xml Data from file
     *
     * @param string $sXmlFilePath
     * @param bool $bOptimize
     */
    public function parseFile( $sXmlFilePath , $bOptimize = false ) {
        $oXml = new XMLReader();
        $this -> bOptimize = (bool) $bOptimize;
        try {
            // Open XML file
            $oXml->open($sXmlFilePath);

            // // Parse Xml and return result
            return $this->parseXml($oXml);

        } catch (Exception $e) {
            echo $e->getMessage(). ' | Try open file: '.$sXmlFilePath;
        }
    }

    /**
     * XML Parser
     *
     * @param XMLReader $oXml
     * @return array
     */
    protected function parseXml( XMLReader $oXml ) {

        $aAssocXML = null;
        $iDc = -1;

        while($oXml->read()){
            switch ($oXml->nodeType) {

                case XMLReader::END_ELEMENT:

                    if ($this->bOptimize) {
                        $this->optXml($aAssocXML);
                    }
                    return $aAssocXML;

                case XMLReader::ELEMENT:

                    if(!isset($aAssocXML[$oXml->name])) {
                        if($oXml->hasAttributes) {
                            $aAssocXML[$oXml->name][] = $oXml->isEmptyElement ? '' : $this->parseXML($oXml);
                        } else {
                            if($oXml->isEmptyElement) {
                                $aAssocXML[$oXml->name] = '';
                            } else {
                                $aAssocXML[$oXml->name] = $this->parseXML($oXml);
                            }
                        }
                    } elseif (is_array($aAssocXML[$oXml->name])) {
                        if (!isset($aAssocXML[$oXml->name][0]))
                        {
                            $temp = $aAssocXML[$oXml->name];
                            foreach ($temp as $sKey=>$sValue)
                            unset($aAssocXML[$oXml->name][$sKey]);
                            $aAssocXML[$oXml->name][] = $temp;
                        }

                        if($oXml->hasAttributes) {
                            $aAssocXML[$oXml->name][] = $oXml->isEmptyElement ? '' : $this->parseXML($oXml);
                        } else {
                            if($oXml->isEmptyElement) {
                                $aAssocXML[$oXml->name][] = '';
                            } else {
                                $aAssocXML[$oXml->name][] = $this->parseXML($oXml);
                            }
                        }
                    } else {
                        $mOldVar = $aAssocXML[$oXml->name];
                        $aAssocXML[$oXml->name] = array($mOldVar);
                        if($oXml->hasAttributes) {
                            $aAssocXML[$oXml->name][] = $oXml->isEmptyElement ? '' : $this->parseXML($oXml);
                        } else {
                            if($oXml->isEmptyElement) {
                                $aAssocXML[$oXml->name][] = '';
                            } else {
                                $aAssocXML[$oXml->name][] = $this->parseXML($oXml);
                            }
                        }
                    }

                    if($oXml->hasAttributes) {
                        $mElement =& $aAssocXML[$oXml->name][count($aAssocXML[$oXml->name]) - 1];
                        while($oXml->moveToNextAttribute()) {
                            $mElement[$oXml->name] = $oXml->value;
                        }
                    }
                    break;
                case XMLReader::TEXT:
                case XMLReader::CDATA:

                    $aAssocXML[++$iDc] = $oXml->value;

            }
        }

        return $aAssocXML;
    }

    /**
     * Method to optimize assoc tree.
     * ( Deleting 0 index when element
     *  have one attribute / value )
     *
     * @param array $mData
     */
    public function optXml(&$mData) {
        if (is_array($mData)) {
            if (isset($mData[0]) && count($mData) == 1 ) {
                $mData = $mData[0];
                if (is_array($mData)) {
                    foreach ($mData as &$aSub) {
                        $this->optXml($aSub);
                    }
                }
            } else {
                foreach ($mData as &$aSub) {
                    $this->optXml($aSub);
                }
            }
        }
    }

}

?>

[EDIT BY danbrown AT php DOT net:  Fixes were also provided by "Alex" and (qdog AT qview DOT org) in user notes on this page (since removed).]
Sergey Aikinkulov 19-Jun-2008 12:51
Next version xml2assoc with some improve fixes:
 - no doubled data
 - no buffer arrays

<?php
/*
    Read XML structure to associative array
    --
    Using:
    $xml = new XMLReader();
    $xml->open([XML file]);
    $assoc = xml2assoc($xml);
    $xml->close();
*/
    function xml2assoc($xml) {
      $assoc = null;
      while($xml->read()){
        switch ($xml->nodeType) {
          case XMLReader::END_ELEMENT: return $assoc;
          case XMLReader::ELEMENT:
            $assoc[$xml->name][] = array('value' => $xml->isEmptyElement ? '' : xml2assoc($xml));
            if($xml->hasAttributes){
              $el =& $assoc[$xml->name][count($assoc[$xml->name]) - 1];
              while($xml->moveToNextAttribute()) $el['attributes'][$xml->name] = $xml->value;
            }
            break;
          case XMLReader::TEXT:
          case XMLReader::CDATA: $assoc .= $xml->value;
        }
      }
      return $assoc;
    }
?>
desk_ocean at msn dot com 16-Mar-2008 07:03
make some modify from Sergey Aikinkulov's note

<?php
function xml2assoc(&$xml){
    $assoc = NULL;
    $n = 0;
    while($xml->read()){
        if($xml->nodeType == XMLReader::END_ELEMENT) break;
        if($xml->nodeType == XMLReader::ELEMENT and !$xml->isEmptyElement){
            $assoc[$n]['name'] = $xml->name;
            if($xml->hasAttributes) while($xml->moveToNextAttribute()) $assoc[$n]['atr'][$xml->name] = $xml->value;
            $assoc[$n]['val'] = xml2assoc($xml);
            $n++;
        }
        else if($xml->isEmptyElement){
            $assoc[$n]['name'] = $xml->name;
            if($xml->hasAttributes) while($xml->moveToNextAttribute()) $assoc[$n]['atr'][$xml->name] = $xml->value;
            $assoc[$n]['val'] = "";
            $n++;               
        }
        else if($xml->nodeType == XMLReader::TEXT) $assoc = $xml->value;
    }
    return $assoc;
}
?>

add else if($xml->isEmptyElement)
may be some xml has emptyelement
itari 15-Feb-2008 05:30
<?php
function parseXML($node,$seq,$path) {
global $oldpath;
    if (!$node->read())
      return;
    if ($node->nodeType != 15) {
      print '<br/>'.$node->depth;
      print '-'.$seq++;
      print '  '.$path.'/'.($node->nodeType==3?'text() = ':$node->name);
      print $node->value;
      if ($node->hasAttributes) {
        print ' [hasAttributes: ';
        while ($node->moveToNextAttribute()) print '@'.$node->name.' = '.$node->value.' ';
        print ']';
        }
      if ($node->nodeType == 1) {
        $oldpath=$path;
        $path.='/'.$node->name;
        }
      parseXML($node,$seq,$path);
      }
    else parseXML($node,$seq,$oldpath);
}

$source = "<tag1>this<tag2 id='4' name='foo'>is</tag2>a<tag2 id='5'>common</tag2>record</tag1>";
$xml = new XMLReader();
$xml->XML($source);
print htmlspecialchars($source).'<br/>';
parseXML($xml,0,'');
?>

Output:

<tag1>this<tag2 id='4' name='foo'>is</tag2>a<tag2 id='5'>common</tag2>record</tag1>

0-0 /tag1
1-1 /tag1/text() = this
1-2 /tag1/tag2 [hasAttributes: @id = 4 @name = foo ]
2-3 /tag1/text() = is
1-4 /text() = a
1-5 /tag2 [hasAttributes: @id = 5 ]
2-6 /text() = common
1-7 /text() = record
orion at ftf-hq dot dk 15-Feb-2006 01:50
Some more documentation (i.e. examples) would be nice :-)

This is how I read some mysql parameters in an xml file:

<?php
    $xml = new XMLReader();
    $xml->open("config.xml");
    $xml->setParserProperty(2,true); // This seems a little unclear to me - but it worked :)

    while ($xml->read()) {
        switch ($xml->name) {
        case "mysql_host":
            $xml->read();
            $conf["mysql_host"] = $xml->value;
            $xml->read();
            break;
        case "mysql_username":
            $xml->read();
            $conf["mysql_user"] = $xml->value;
            $xml->read();
            break;
        case "mysql_password":
            $xml->read();
            $conf["mysql_pass"] = $xml->value;
            $xml->read();
            break;
        case "mysql_database":
            $xml->read();
            $conf["mysql_db"] = $xml->value;
            $xml->read();
            break;
        }
    }

    $xml->close();
?>

The XML file used:
<?xml version='1.0'?>
<MySQL_INIT>
   <mysql_host>localhost</mysql_host>
   <mysql_database>db_database</mysql_database>
   <mysql_username>root</mysql_username>
   <mysql_password>password</mysql_password>
</MySQL_INIT>