/*
 * This file is part of the DOM implementation for KDE.
 *
 * (C) 1999 Lars Knoll (knoll@kde.org)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * This file includes excerpts from the Document Object Model (DOM)
 * Level 1 Specification (Recommendation)
 * http://www.w3.org/TR/REC-DOM-Level-1/
 * Copyright © World Wide Web Consortium , (Massachusetts Institute of
 * Technology , Institut National de Recherche en Informatique et en
 * Automatique , Keio University ). All Rights Reserved.
 *
 * $Id: dom_element.h,v 1.15 2001/06/02 04:18:00 pmk Exp $
 */
#ifndef _DOM_ELEMENT_h_
#define _DOM_ELEMENT_h_

#include <dom/dom_node.h>
#include <dom/css_value.h>

namespace DOM {

class DOMString;
class AttrImpl;
class ElementImpl;
class NamedAttrMapImpl;

/**
 * The <code> Attr </code> interface represents an attribute in an
 * <code> Element </code> object. Typically the allowable values for
 * the attribute are defined in a document type definition.
 *
 *  <code> Attr </code> objects inherit the <code> Node </code>
 * interface, but since they are not actually child nodes of the
 * element they describe, the DOM does not consider them part of the
 * document tree. Thus, the <code> Node </code> attributes <code>
 * parentNode </code> , <code> previousSibling </code> , and <code>
 * nextSibling </code> have a null value for <code> Attr </code>
 * objects. The DOM takes the view that attributes are properties of
 * elements rather than having a separate identity from the elements
 * they are associated with; this should make it more efficient to
 * implement such features as default attributes associated with all
 * elements of a given type. Furthermore, <code> Attr </code> nodes
 * may not be immediate children of a <code> DocumentFragment </code>
 * . However, they can be associated with <code> Element </code> nodes
 * contained within a <code> DocumentFragment </code> . In short,
 * users and implementors of the DOM need to be aware that <code> Attr
 * </code> nodes have some things in common with other objects
 * inheriting the <code> Node </code> interface, but they also are
 * quite distinct.
 *
 *  The attribute's effective value is determined as follows: if this
 * attribute has been explicitly assigned any value, that value is the
 * attribute's effective value; otherwise, if there is a declaration
 * for this attribute, and that declaration includes a default value,
 * then that default value is the attribute's effective value;
 * otherwise, the attribute does not exist on this element in the
 * structure model until it has been explicitly added. Note that the
 * <code> nodeValue </code> attribute on the <code> Attr </code>
 * instance can also be used to retrieve the string version of the
 * attribute's value(s).
 *
 *  In XML, where the value of an attribute can contain entity
 * references, the child nodes of the <code> Attr </code> node provide
 * a representation in which entity references are not expanded. These
 * child nodes may be either <code> Text </code> or <code>
 * EntityReference </code> nodes. Because the attribute type may be
 * unknown, there are no tokenized attribute values.
 *
 */
class Attr : public Node
{
    friend class Element;
    friend class Document;
    friend class HTMLDocument;
    friend class ElementImpl;
    friend class NamedAttrMapImpl;

public:
    Attr();
    Attr(const Node &other) : Node()
        {(*this)=other;}
    Attr(const Attr &other);

    Attr & operator = (const Node &other);
    Attr & operator = (const Attr &other);

    ~Attr();

    /**
     * Returns the name of this attribute.
     *
     */
    DOMString name() const;

    /**
     * If this attribute was explicitly given a value in the original
     * document, this is <code> true </code> ; otherwise, it is <code>
     * false </code> . Note that the implementation is in charge of
     * this attribute, not the user. If the user changes the value of
     * the attribute (even if it ends up having the same value as the
     * default value) then the <code> specified </code> flag is
     * automatically flipped to <code> true </code> . To re-specify
     * the attribute as the default value from the DTD, the user must
     * delete the attribute. The implementation will then make a new
     * attribute available with <code> specified </code> set to <code>
     * false </code> and the default value (if one exists).
     *
     *  In summary: <ulist> <item> If the attribute has an assigned
     * value in the document then <code> specified </code> is <code>
     * true </code> , and the value is the assigned value.
     *
     *  </item> <item> If the attribute has no assigned value in the
     * document and has a default value in the DTD, then <code>
     * specified </code> is <code> false </code> , and the value is
     * the default value in the DTD.
     *
     *  </item> <item> If the attribute has no assigned value in the
     * document and has a value of #IMPLIED in the DTD, then the
     * attribute does not appear in the structure model of the
     * document.
     *
     *  </item> </ulist>
     *
     */
    bool specified() const;

    /**
     * On retrieval, the value of the attribute is returned as a
     * string. Character and general entity references are replaced
     * with their values.
     *
     *  On setting, this creates a <code> Text </code> node with the
     * unparsed contents of the string.
     *
     */
    DOMString value() const;

    /**
     * see @ref value
     */
    void setValue( const DOMString & );

protected:

    Attr( AttrImpl *_impl );
};

class NodeList;
class Attr;
class DOMString;

/**
 * By far the vast majority of objects (apart from text) that authors
 * encounter when traversing a document are <code> Element </code>
 * nodes. Assume the following XML document: &lt;elementExample
 * id=&quot;demo&quot;&gt; &lt;subelement1/&gt;
 * &lt;subelement2&gt;&lt;subsubelement/&gt;&lt;/subelement2&gt;
 * &lt;/elementExample&gt;
 *
 *  When represented using DOM, the top node is an <code> Element
 * </code> node for &quot;elementExample&quot;, which contains two
 * child <code> Element </code> nodes, one for &quot;subelement1&quot;
 * and one for &quot;subelement2&quot;. &quot;subelement1&quot;
 * contains no child nodes.
 *
 *  Elements may have attributes associated with them; since the
 * <code> Element </code> interface inherits from <code> Node </code>
 * , the generic <code> 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> Element
 * </code> interface to retrieve either an <code> Attr </code> object
 * by name or an attribute value by name. In XML, where an attribute
 * value may contain entity references, an <code> 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 Element : public Node
{
    friend class Document;
    friend class HTMLDocument;

public:
    Element();
    Element(const Node &other) : Node()
        {(*this)=other;}
    Element(const Element &other);

    Element & operator = (const Node &other);
    Element & operator = (const Element &other);

    ~Element();

    /**
     * The name of the element. For example, in: &lt;elementExample
     * id=&quot;demo&quot;&gt; ... &lt;/elementExample&gt; , <code>
     * tagName </code> has the value <code> &quot;elementExample&quot;
     * </code> . Note that this is case-preserving in XML, as are all
     * of the operations of the DOM. The HTML DOM returns the <code>
     * tagName </code> of an HTML element in the canonical uppercase
     * form, regardless of the case in the source HTML document.
     *
     */
    DOMString tagName() const;

    /**
     * Retrieves an attribute value by name.
     *
     * @param name The name of the attribute to retrieve.
     *
     * @return The <code> 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 );

    /**
     * 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>
     * 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.
     *
     * @return
     *
     * @exception DOMException
     * INVALID_CHARACTER_ERR: Raised if the specified name contains an
     * invalid character.
     *
     *  NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
     *
     */
    void setAttribute ( const DOMString &name, const DOMString &value );

    /**
     * Removes an attribute by name. If the removed attribute has a
     * default value it is immediately replaced.
     *
     * @param name The name of the attribute to remove.
     *
     * @return
     *
     * @exception DOMException
     * NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
     *
     */
    void removeAttribute ( const DOMString &name );

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

    /**
     * Adds a new attribute. If an attribute with that name is already
     * present in the element, it is replaced by the new one.
     *
     * @param newAttr The <code> Attr </code> node to add to the
     * attribute list.
     *
     * @return If the <code> newAttr </code> attribute replaces an
     * existing attribute with the same name, the previously existing
     * <code> Attr </code> node is returned, otherwise <code> null
     * </code> is returned.
     *
     * @exception DOMException
     * WRONG_DOCUMENT_ERR: Raised if <code> newAttr </code> was
     * created from a different document than the one that created the
     * element.
     *
     *  NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
     *
     *  INUSE_ATTRIBUTE_ERR: Raised if <code> newAttr </code> is
     * already an attribute of another <code> Element </code> object.
     * The DOM user must explicitly clone <code> Attr </code> nodes to
     * re-use them in other elements.
     *
     */
    Attr setAttributeNode ( const Attr &newAttr );

    /**
     * Removes the specified attribute.
     *
     * @param oldAttr The <code> Attr </code> node to remove from the
     * attribute list. If the removed <code> Attr </code> has a
     * default value it is immediately replaced.
     *
     * @return The <code> Attr </code> node that was removed.
     *
     * @exception DOMException
     * NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly.
     *
     *  NOT_FOUND_ERR: Raised if <code> oldAttr </code> is not an
     * attribute of the element.
     *
     */
    Attr removeAttributeNode ( const Attr &oldAttr );

    /**
     * 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> 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> Element </code> nodes.
     *
     */
    NodeList getElementsByTagName ( const DOMString &name );

    /**
     * Puts all <code> Text </code> nodes in the full depth of the
     * sub-tree underneath this <code> Element </code> into a "normal"
     * form where only markup (e.g., tags, comments, processing
     * instructions, CDATA sections, and entity references) separates
     * <code> Text </code> nodes, i.e., there are no adjacent <code>
     * Text </code> nodes. This can be used to ensure that the DOM
     * view of a document is the same as if it were saved and
     * re-loaded, and is useful when operations (such as XPointer
     * lookups) that depend on a particular document tree structure
     * are to be used.
     *
     * @return
     *
     */
    void normalize (  );

    /**
     * Introduced in DOM Level 2
     * This method is from the CSSStyleDeclaration interface
     *
     * The style attribute
     */
    CSSStyleDeclaration style (  );

    /**
     * @internal
     * not part of the DOM
     */
    bool isHTMLElement() const;

protected:

    Element(ElementImpl *_impl);
};

}; //namespace
#endif
