dom_element.hpp

基于属性证书的访问控制源代码,由c++编写,包括openssl,xercesc等

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/*
 * $Id: DOM_Element.hpp,v 1.4 2003/01/03 16:40:13 tng Exp $
 */

#ifndef DOM_Element_HEADER_GUARD_
#define DOM_Element_HEADER_GUARD_

#include <xercesc/util/XercesDefs.hpp>
#include "DOM_Node.hpp"

XERCES_CPP_NAMESPACE_BEGIN


class DOM_Attr;
class DOM_NodeList;
class ElementImpl;

/**
 * By far the vast majority of objects (apart from text) that authors
 * encounter when traversing a document are <code>DOM_Element</code> nodes.
 *
 * Assume the following XML document:&lt;elementExample id="demo"&gt;
 * &lt;subelement1/&gt;
 * &lt;subelement2&gt;&lt;subsubelement/&gt;&lt;/subelement2&gt;
 * &lt;/elementExample&gt;
 * <p>When represented using DOM, the top node is an <code>DOM_Element</code> node
 * for "elementExample", which contains two child <code>DOM_Element</code> nodes,
 * one for "subelement1" and one for "subelement2". "subelement1" contains no
 * child nodes.
 * <p>Elements may have attributes associated with them; since the
 * <code>DOM_Element</code> interface inherits from <code>DOM_Node</code>, the generic
 *  <code>DOM_Node</code> interface method <code>getAttributes</code> may be used
 * to retrieve the set of all attributes for an element.  There are methods on
 *  the <code>DOM_Element</code> interface to retrieve either an <code>DOM_Attr</code>
 *  object by name or an attribute value by name. In XML, where an attribute
 * value may contain entity references, an <code>DOM_Attr</code> object should be
 * retrieved to examine the possibly fairly complex sub-tree representing the
 * attribute value. On the other hand, in HTML, where all attributes have
 * simple string values, methods to directly access an attribute value can
 * safely be used as a convenience.
 */

class CDOM_EXPORT DOM_Element: public DOM_Node {
private:

public:
    /** @name Constructors and assignment operator */
    //@{
    /**
    * Default constructor for DOM_Element.  The resulting object does not
    * refer to an actual Element node; it will compare == to 0, and is similar
    * to a null object reference variable in Java.  It may subsequently be
    * assigned to refer to an actual Element node.
    * <p>
    * New comment nodes are created by DOM_Document::createElement().
      *
      */
    DOM_Element();

    /**
      * Copy constructor.  Creates a new <code>DOM_Element</code> that refers to the
      * same underlying actual element as the original.
      *
      * @param other The object to be copied
      */
    DOM_Element(const DOM_Element &other);

    /**
      * Assignment operator.
      *
      * @param other The object to be copied.
      */
    DOM_Element & operator = (const DOM_Element &other);

    /**
      * Assignment operator.  This overloaded variant is provided for
      *   the sole purpose of setting a DOM_Node reference variable to
      *   zero.  Nulling out a reference variable in this way will decrement
      *   the reference count on the underlying Node object that the variable
      *   formerly referenced.  This effect is normally obtained when reference
      *   variable goes out of scope, but zeroing them can be useful for
      *   global instances, or for local instances that will remain in scope
      *   for an extended time,  when the storage belonging to the underlying
      *   node needs to be reclaimed.
      *
      * @param val   Only a value of 0, or null, is allowed.
      */
    DOM_Element & operator = (const DOM_NullPtr *val);

    //@}
    /** @name Destructor. */
    //@{
	 /**
      * Destructor.  The object being destroyed is the reference
      * object, not the underlying Element itself.
	  *
	  */
    ~DOM_Element();
    //@}
    /** @name Getter functions. */
    //@{

  /**
   * The name of the element.
   *
   * For example, in: &lt;elementExample
   * id="demo"&gt;  ... &lt;/elementExample&gt; , <code>tagName</code> has
   * the value <code>"elementExample"</code>. Note that this is
   * case-preserving in XML, as are all of the operations of the DOM.
   */
  DOMString         getTagName() const;

  /**
   * Retrieves an attribute value by name.
   *
   * @param name The name of the attribute to retrieve.
   * @return The <code>DOM_Attr</code> value as a string, or the empty  string if
   *   that attribute does not have a specified or default value.
   */
  DOMString         getAttribute(const DOMString &name) const;

  /**
   * Retrieves an <code>DOM_Attr</code> node by name.
   *
   * @param name The name (<CODE>nodeName</CODE>) of the attribute to retrieve.
   * @return The <code>DOM_Attr</code> node with the specified name (<CODE>nodeName</CODE>) or
   *   <code>null</code> if there is no such attribute.
   */
  DOM_Attr        getAttributeNode(const DOMString &name) const;

  /**
   * Returns a <code>NodeList</code> of all descendant elements with a given
   * tag name, in the order in which they would be encountered in a preorder
   * traversal of the <code>DOM_Element</code> tree.
   *
   * @param name The name of the tag to match on. The special value "*"
   *   matches all tags.
   * @return A list of matching <code>DOM_Element</code> nodes.
   */
  DOM_NodeList    getElementsByTagName(const DOMString &name) const;

  //@}
  /** @name Set functions. */
  //@{

  /**
   * Adds a new attribute.
   *
   * If an attribute with that name is already present
   * in the element, its value is changed to be that of the value parameter.
   * This value is a simple string, it is not parsed as it is being set. So
   * any markup (such as syntax to be recognized as an entity reference) is
   * treated as literal text, and needs to be appropriately escaped by the
   * implementation when it is written out. In order to assign an attribute
   * value that contains entity references, the user must create an
   * <code>DOM_Attr</code> node plus any <code>Text</code> and
   * <code>EntityReference</code> nodes, build the appropriate subtree, and
   * use <code>setAttributeNode</code> to assign it as the value of an
   * attribute.
   * @param name The name of the attribute to create or alter.
   * @param value Value to set in string form.
   * @exception DOMException
   *   INVALID_CHARACTER_ERR: Raised if the specified name contains an
   *   illegal character.
   *   <br>NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
   */
   void             setAttribute(const DOMString &name,
                                 const DOMString &value);
   /**
    * Adds a new attribute.
    *