使用registerNodeClass扩展PHP中的DomeElement

registerNodeClass

非常适合在PHP中扩展各种基于DOMNode的DOM类，但我需要更深入一层

---

我创建了一个扩展

DOMElement

的

extDOMElement

。这在

registerNodeClass

中非常有效，但我希望有一些更像这样的功能：

registerNodeClass（“doElement->nodeName='XYZ'，'extDOMXYZElement'）

考虑以下XML文档，anives.XML：

<animals>
    <dog name="fido" />
    <dog name="lucky" />
    <cat name="scratchy" />
    <horse name="flicka" />
</animals>

输出： 狗叫了！ 幸运的是狗会吠！ 猫在叫！ 弗利卡，马在呜呜叫

我不想把bark（）、meow（）和whinny（）放到extdomement中，我想把它们分别放到extDOMDogElement、extdomcateelement和extdomhorselement中

---

我已经看过了这里的装饰和策略模式，但我不确定如何继续。当前的设置工作正常，但我更喜欢在

extdomeElement

中共享属性和方法，每个ElementName都有单独的类，这样我就可以将每个元素特定的方法和属性从主类中分离出来。

编辑您显示的代码，不扩展DOMElement不是更容易吗？只需将常规的家庭元素传递给你的处理策略，例如

class AnimalProcessor
{
    public function processAnimals(DOMDocument $dom) {
        foreach($dom->documentElement->childNodes as $animal) {
            $strategy = $animal->tagName . 'Strategy';
            $strategy = new $strategy($animal);
            $strategy->process();
        }
    }
}

$dom = new DOMDocument;
$dom->load('animals.xml');
$processor = new AnimalProcessor;
$processor->processAnimals($dom);

---

问题更新前的原始答案

---

不确定这是否是您想要的，但是如果您想要专门的domeElement，您可以简单地创建它们并直接使用它们，例如绕过

createElement

，这样您就不必注册

registerNodeClass

class DogElement extends DOMElement
{
    public function __construct($value) 
    {
        parent::__construct('dog', $value);
    }
}
class CatElement extends DOMElement
{
    public function __construct($value) 
    {
        parent::__construct('cat', $value);
    }
}
$dom = new DOMDocument;
$dom->loadXML('<animals/>');
$dom->documentElement->appendChild(new DogElement('Sparky'));
$dom->documentElement->appendChild(new CatElement('Tinky'));
echo $dom->saveXml();

---

我不能确切地指出这一点，但正如已经指出的那样，您正在尝试的是一种特定的方式。
无论如何根据实际节点（类型/contents/…），可以使用在extdoElement对象上公开不同的方法。为此，extdoElement对象可以存储一个助手对象，该对象根据元素的“类型”实例化，然后将方法调用委托给该助手对象。就我个人而言，我不太喜欢这样，因为这样做并不能使文档编制、测试和调试变得更容易。如果你觉得可行的话，我可以写一个完整的例子

---

这当然需要评论/文档…工作正在进行中，因为我现在没有时间

<?php
$doc = new MyDOMDocument('1.0', 'iso-8859-1');
$doc->loadxml('<animals>
  <Foo name="fido" />
  <Bar name="lucky" />
  <Foo name="scratchy" />
  <Ham name="flicka" />
  <Egg name="donald" />
</animals>');
$xpath = new DOMXPath($doc);
foreach( $xpath->query('//Foo') as $e ) {
  echo $e->name(), ': ', $e->foo(), "\n";
}
echo "----\n";
foreach( $xpath->query('//Bar') as $e ) {
  echo $e->name(), ': ', $e->bar(), "\n";
}
echo "====\n";
echo $doc->savexml();


class MyDOMElement extends DOMElement {
  protected $helper;

  public function getHelper() {
    // lazy loading and caching the helper object
    // since lookup/instantiation can be costly
    if ( is_null($this->helper) ) {
      $this->helper = $this->resolveHelper();
    }
    return $this->helper;
  }

  public function isType($t) {
    return $this->getHelper() instanceof $t;
  }

  public function __call($name, $args) {
    $helper = $this->getHelper();
    if ( !method_exists($helper, $name) ) {
      var_dump($name, $args, $helper);
      throw new Exception('yaddayadda');
    }
    return call_user_func_array( array($this->helper, $name), $args);
  }

  public function releaseHelper() {
    // you might want to consider something like this
    // to help php with the circular references
    // ...or maybe not, haven't tested the impact circual references have on php's gc
    $this->helper = null;
  }

  protected function resolveHelper() {
    // this is hardcored only for brevity's sake
    // add any kind of lookup/factory/... you like
    $rv = null;
    switch( $this->tagName ) {
      case 'Foo':
      case 'Bar':
        $cn = "DOMHelper".$this->tagName;
        return new $cn($this);
      default:
        return new DOMHelper($this);
        break;
    }
  }
}

class MyDOMDocument extends DOMDocument {
  public function __construct($version=null,$encoding=null) {
    parent::__construct($version,$encoding);
    $this->registerNodeClass('DOMElement', 'MyDOMElement');
  }
}

class DOMHelper {
  protected $node;
  public function __construct(DOMNode $node) {
    $this->node = $node;
  }
  public function name() { return $this->node->getAttribute("name"); }
}

class DOMHelperFoo extends DOMHelper {
  public function foo() {
    echo 'foo';
    $this->node->appendChild(  $this->node->ownerDocument->createElement('action', 'something'));
  }
}

class DOMHelperBar extends DOMHelper {
  public function bar() {
    echo 'bar';
    $this->node->setAttribute('done', '1');
  }
}

query（'//Foo'）作为$e）{
echo$e->name（），“：”，$e->foo（），“\n”；
}
回显“---\n”；
foreach（$xpath->query（'//Bar'）作为$e）{
回显$e->name（），“：”，$e->bar（），“\n”；
}
回显“==\n”；
echo$doc->savexml（）；
类MyDomeElement扩展了DomeElement{
受保护的$helper；
公共函数getHelper（）{
//延迟加载和缓存辅助对象
//因为查找/实例化可能代价高昂
如果（为空（$this->helper））{
$this->helper=$this->resolvehlper（）；
}
返回$this->helper；
}
公共函数isType（$t）{
返回$t的$this->getHelper（）实例；
}
公共函数调用（$name，$args）{
$helper=$this->getHelper（）；
如果（！方法_存在（$helper，$name））{
变量转储（$name、$args、$helper）；
抛出新异常（'yaddayada'）；
}
返回call\u user\u func\u数组（数组（$this->helper，$name），$args）；
}
公共函数releaseheloper（）{
你可能想考虑这样的事情。
//帮助php使用循环引用
//…或者可能不是，还没有测试循环引用对php的gc的影响
$this->helper=null；
}
受保护的函数resolveHelper（）{
//这只是为了简洁起见而精雕细琢的
//添加任何您喜欢的查找/工厂/…类型
$rv=null；
开关（$this->tagName）{
案例“Foo”：
“酒吧”一案：
$cn=“DOMHelper”。$this->tagName；
返回新的$cn（$this）；
违约：
返回新的DOMHelper（$this）；
打破
}
}
}
类MyDOMDocument扩展了DOMDocument{
公共函数构造（$version=null，$encoding=null）{
父项：：__构造（$version，$encoding）；
$this->registerNodeClass（'DomeElement'，'MyDomeElement'）；
}
}
类DOMHelper{
受保护的$节点；
公共函数构造（DOMNode$node）{
$this->node=$node；
}
公共函数名（）{return$this->node->getAttribute（“name”）；}
}
类DOMHelperFoo扩展了DOMHelper{
公共功能foo（）{
回声“foo”；
$this->node->appendChild（$this->node->ownerDocument->createElement（'action'，'something'）；
}
}
类DOMHelperBar扩展了DOMHelper{
公共功能条（）{
回声“条”；
$this->node->setAttribute（'done'，'1'）；
}
}

印刷品

fido: foo
scratchy: foo
----
lucky: bar
====
<?xml version="1.0"?>
<animals>
  <Foo name="fido"><action>something</action></Foo>
  <Bar name="lucky" done="1"/>
  <Foo name="scratchy"><action>something</action></Foo>
  <Ham name="flicka"/>
  <Egg name="donald"/>
</animals>

fido:foo
抓痒：福
----
幸运儿：酒吧
====
某物
某物

我也有同样的问题。我的解决方案是基于XMLReader扩展编写自己的解析器。由此产生的AdvancedParser类对我来说工作得非常好。可以为每个元素名称注册一个单独的元素类。通过扩展AdvancedParser类并覆盖getClassForElement（）方法，还可以基于元素名动态计算所需类的名称

/**
 * Specialized Xml parser with element based class registry.
 * 
 * This class uses the XMLReader extension for document parsing and creates
 * a DOM tree with individual DOMElement subclasses for each element type.
 * 
 * @author       Andreas Traber < a.traber (at) rivo-systems (dot) com >
 * 
 * @since        April 21, 2012
 * @package      XML
 */
class AdvancedParser
{
    /**
     * Map with registered classes.
     * @var array
     */
    protected $_elementClasses = array();

    /**
     * Default class for unknown elements.
     * @var string
     */
    protected $_defaultElementClass = 'DOMElement';

    /**
     * The reader for Xml parsing.
     * @var XMLReader
     */
    protected $_reader;

    /**
     * The document object.
     * @var DOMDocument
     */
    protected $_document;

    /**
     * The current parsing element.
     * @var DOMElement
     */
    protected $_currentElement;

    /**
     * Gets the fallback class for unknown elements.
     * 
     * @return string
     */
    public function getDefaultElementClass()
    {
        return $this->_defaultElementClass;
    }

    /**
     * Sets the fallback class for unknown elements.
     * 
     * @param string $class
     * @return void
     * @throws Exception $class is not a subclass of DOMElement.
     */
    public function setDefaultElementClass($class)
    {
        switch (true) {
            case $class === null:
                $this->_defaultElementClass = 'DOMElement';
                break;

            case !$class instanceof DOMElement:
                throw new Exception($class.' must be a subclass of DOMElement');

            default:
                $this->_defaultElementClass = $class;
        }
    }

    /**
     * Registers the class for a specified element name.
     * 
     * @param string $elementName.
     * @param string $class.
     * @return void
     * @throws Exception $class is not a subclass of DOMElement.
     */
    public function registerElementClass($elementName, $class)
    {
        switch (true) {
            case $class === null:
                unset($this->_elementClasses[$elementName]);
                break;

            case !$class instanceof DOMElement:
                throw new Exception($class.' must be a subclass of DOMElement');

            default:
                $this->_elementClasses[$elementName] = $class;
        }
    }

    /**
     * Gets the class for a given element name.
     * 
     * @param string $elementName
     * @return string
     */
    public function getClassForElement($elementName)
    {
        return $this->_elementClasses[$elementName]
            ? $this->_elementClasses[$elementName]
            : $this->_defaultElementClass;
    }

    /**
     * Parse Xml Data from string.
     * 
     * @see XMLReader::XML()
     * 
     * @param string $source String containing the XML to be parsed.
     * @param string $encoding The document encoding or NULL.
     * @param string $options A bitmask of the LIBXML_* constants.
     * @return DOMDocument The created DOM tree.
     */
    public function parseString($source, $encoding = null, $options = 0)
    {
        $this->_reader = new XMLReader();
        $this->_reader->XML($source, $encoding, $options);
        return $this->_parse();
    }

    /**
     * Parse Xml Data from file.
     * 
     * @see XMLReader::open()
     * 
     * @param string $uri URI pointing to the document.
     * @param string $encoding The document encoding or NULL.
     * @param string $options A bitmask of the LIBXML_* constants.
     * @return DOMDocument The created DOM tree.
     */
    public function parseFile($uri, $encoding = null, $options = 0)
    {
        $this->_reader = new XMLReader();
        $this->_reader->open($uri, $encoding, $options);
        return $this->_parse();
    }

    /**
     * The parser.
     * 
     * @return DOMDocument The created DOM tree.
     */
    protected function _parse()
    {
        $this->_document = new DOMDocument('1.0', 'utf-8');
        $this->_document->_elements = array(); // keep references to elements
        $this->_currentElement = $this->_document;
        while ($this->_reader->read()) {
            switch ($this->_reader->nodeType) {
                case XMLReader::ELEMENT:
                    $this->_reader->isEmptyElement
                        ? $this->_addElement()
                        : $this->_currentElement = $this->_addElement();
                    break;

                case XMLReader::END_ELEMENT:
                    $this->_currentElement = $this->_currentElement->parentNode;
                    break;

                case XMLReader::CDATA:
                    $this->_currentElement->appendChild(
                        $this->_document->createCDATASection($this->_reader->value)
                    );
                    break;

                case XMLReader::TEXT:
                case XMLReader::SIGNIFICANT_WHITESPACE:
                    $this->_currentElement->appendChild(
                        $this->_document->createTextNode($this->_reader->value)
                    );
                    break;

                case XMLReader::COMMENT:
                    $this->_currentElement->appendChild(
                        $this->_document->createComment($this->_reader->value)
                    );
                    break;
            }
        }
        $this->_reader->close();
        return $this->_document;
    }

    /**
     * Adds the current element into the DOM tree.
     * 
     * @return DOMElement The added element.
     */
    protected function _addElement()
    {
        $element = $this->_createElement();

        // It's important to keep a reference to each element.
        // Elements without any reference were destroyed by the
        // garbage collection and loses their type.
        $this->_document->_elements[] = $element;

        $this->_currentElement->appendChild($element);
        $this->_addAttributes($element);
        return $element;
    }

    /**
     * Creates a new element.
     * 
     * @return DOMElement The created element.
     */
    protected function _createElement()
    {
        $class = $this->getClassForElement($this->_reader->localName);
        return new $class(
            $this->_reader->name,
            $this->_reader->value,
            $this->_reader->namespaceURI
        );
    }

    /**
     * Adds the current attributes to an $element.
     * 
     * @param DOMElement $element
     * @return void
     */
    protected function _addAttributes(DOMElement $element)
    {
        while ($this->_reader->moveToNextAttribute()) {
            $this->_reader->prefix && ($uri = $this->_reader->lookupNamespace($this->_reader->prefix))
                ? $element->setAttributeNS($uri, $this->_reader->name, $this->_reader->value)
                : $element->setAttribute($this->_reader->name, $this->_reader->value);
        }
    }
}

/**
*具有基于元素的类注册表的专用Xml解析器。
* 
*此类使用XMLReader扩展进行文档解析并创建
*一个DOM树，每个元素类型都有单独的DomeElement子类。
* 
*@author Andreas Traber
* 
*@自2012年4月21日起
*@package-XML
*/
类高级语法分析器
{
/**
*映射已注册的类。
*@var数组
*/
受保护的$_elementClasses=array（）；
/**
*未知元素的默认类。
*@var字符串
*/
受保护的$\u defaultElementClass='DomeElement'；
/**
*用于Xml解析的读取器。
*@var XMLReader
*/
受保护的$u读取器；
/**
*文档对象。
*@var DOMDocument
*/
受保护的$u文件；
/**
*狗
fido: foo
scratchy: foo
----
lucky: bar
====
<?xml version="1.0"?>
<animals>
  <Foo name="fido"><action>something</action></Foo>
  <Bar name="lucky" done="1"/>
  <Foo name="scratchy"><action>something</action></Foo>
  <Ham name="flicka"/>
  <Egg name="donald"/>
</animals>

/**
 * Specialized Xml parser with element based class registry.
 * 
 * This class uses the XMLReader extension for document parsing and creates
 * a DOM tree with individual DOMElement subclasses for each element type.
 * 
 * @author       Andreas Traber < a.traber (at) rivo-systems (dot) com >
 * 
 * @since        April 21, 2012
 * @package      XML
 */
class AdvancedParser
{
    /**
     * Map with registered classes.
     * @var array
     */
    protected $_elementClasses = array();

    /**
     * Default class for unknown elements.
     * @var string
     */
    protected $_defaultElementClass = 'DOMElement';

    /**
     * The reader for Xml parsing.
     * @var XMLReader
     */
    protected $_reader;

    /**
     * The document object.
     * @var DOMDocument
     */
    protected $_document;

    /**
     * The current parsing element.
     * @var DOMElement
     */
    protected $_currentElement;

    /**
     * Gets the fallback class for unknown elements.
     * 
     * @return string
     */
    public function getDefaultElementClass()
    {
        return $this->_defaultElementClass;
    }

    /**
     * Sets the fallback class for unknown elements.
     * 
     * @param string $class
     * @return void
     * @throws Exception $class is not a subclass of DOMElement.
     */
    public function setDefaultElementClass($class)
    {
        switch (true) {
            case $class === null:
                $this->_defaultElementClass = 'DOMElement';
                break;

            case !$class instanceof DOMElement:
                throw new Exception($class.' must be a subclass of DOMElement');

            default:
                $this->_defaultElementClass = $class;
        }
    }

    /**
     * Registers the class for a specified element name.
     * 
     * @param string $elementName.
     * @param string $class.
     * @return void
     * @throws Exception $class is not a subclass of DOMElement.
     */
    public function registerElementClass($elementName, $class)
    {
        switch (true) {
            case $class === null:
                unset($this->_elementClasses[$elementName]);
                break;

            case !$class instanceof DOMElement:
                throw new Exception($class.' must be a subclass of DOMElement');

            default:
                $this->_elementClasses[$elementName] = $class;
        }
    }

    /**
     * Gets the class for a given element name.
     * 
     * @param string $elementName
     * @return string
     */
    public function getClassForElement($elementName)
    {
        return $this->_elementClasses[$elementName]
            ? $this->_elementClasses[$elementName]
            : $this->_defaultElementClass;
    }

    /**
     * Parse Xml Data from string.
     * 
     * @see XMLReader::XML()
     * 
     * @param string $source String containing the XML to be parsed.
     * @param string $encoding The document encoding or NULL.
     * @param string $options A bitmask of the LIBXML_* constants.
     * @return DOMDocument The created DOM tree.
     */
    public function parseString($source, $encoding = null, $options = 0)
    {
        $this->_reader = new XMLReader();
        $this->_reader->XML($source, $encoding, $options);
        return $this->_parse();
    }

    /**
     * Parse Xml Data from file.
     * 
     * @see XMLReader::open()
     * 
     * @param string $uri URI pointing to the document.
     * @param string $encoding The document encoding or NULL.
     * @param string $options A bitmask of the LIBXML_* constants.
     * @return DOMDocument The created DOM tree.
     */
    public function parseFile($uri, $encoding = null, $options = 0)
    {
        $this->_reader = new XMLReader();
        $this->_reader->open($uri, $encoding, $options);
        return $this->_parse();
    }

    /**
     * The parser.
     * 
     * @return DOMDocument The created DOM tree.
     */
    protected function _parse()
    {
        $this->_document = new DOMDocument('1.0', 'utf-8');
        $this->_document->_elements = array(); // keep references to elements
        $this->_currentElement = $this->_document;
        while ($this->_reader->read()) {
            switch ($this->_reader->nodeType) {
                case XMLReader::ELEMENT:
                    $this->_reader->isEmptyElement
                        ? $this->_addElement()
                        : $this->_currentElement = $this->_addElement();
                    break;

                case XMLReader::END_ELEMENT:
                    $this->_currentElement = $this->_currentElement->parentNode;
                    break;

                case XMLReader::CDATA:
                    $this->_currentElement->appendChild(
                        $this->_document->createCDATASection($this->_reader->value)
                    );
                    break;

                case XMLReader::TEXT:
                case XMLReader::SIGNIFICANT_WHITESPACE:
                    $this->_currentElement->appendChild(
                        $this->_document->createTextNode($this->_reader->value)
                    );
                    break;

                case XMLReader::COMMENT:
                    $this->_currentElement->appendChild(
                        $this->_document->createComment($this->_reader->value)
                    );
                    break;
            }
        }
        $this->_reader->close();
        return $this->_document;
    }

    /**
     * Adds the current element into the DOM tree.
     * 
     * @return DOMElement The added element.
     */
    protected function _addElement()
    {
        $element = $this->_createElement();

        // It's important to keep a reference to each element.
        // Elements without any reference were destroyed by the
        // garbage collection and loses their type.
        $this->_document->_elements[] = $element;

        $this->_currentElement->appendChild($element);
        $this->_addAttributes($element);
        return $element;
    }

    /**
     * Creates a new element.
     * 
     * @return DOMElement The created element.
     */
    protected function _createElement()
    {
        $class = $this->getClassForElement($this->_reader->localName);
        return new $class(
            $this->_reader->name,
            $this->_reader->value,
            $this->_reader->namespaceURI
        );
    }

    /**
     * Adds the current attributes to an $element.
     * 
     * @param DOMElement $element
     * @return void
     */
    protected function _addAttributes(DOMElement $element)
    {
        while ($this->_reader->moveToNextAttribute()) {
            $this->_reader->prefix && ($uri = $this->_reader->lookupNamespace($this->_reader->prefix))
                ? $element->setAttributeNS($uri, $this->_reader->name, $this->_reader->value)
                : $element->setAttribute($this->_reader->name, $this->_reader->value);
        }
    }
}