/*

* Copyright (c) 2004-2006 Nokia Corporation and/or its subsidiary(-ies). 

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of the License "Symbian Foundation License v1.0" to Symbian Foundation members and "Symbian Foundation End User License Agreement v1.0" to non-members

* which accompanies this distribution, and is available

* at the URL "http://www.symbianfoundation.org/legal/licencesv10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:       Namespace node functions

*

*/

#ifndef XMLENGINE_NAMESPACE_H_INCLUDED

#define XMLENGINE_NAMESPACE_H_INCLUDED

#include "xmlengnode.h"

/**

 *   Represents existing namespace declaration in DOM tree <b>OR</b> namespace node returned

 *   in RXmlEngNodeSet as a result of some XPath expression. 

 *

 *   All elements and attributes may have a namespace instance associated.

 *   Once put in element, a namespace declaration (instance of TXmlEngNamespace) may be 

 *   referred to by all attributes and descentants of the element (unless

 *   prefix that this namespace-to-prefix binding uses is overriden somewhere below in the document tree)

 *

 *   <b>General rules of namespace handling:</b>

 *

 * - <b>NULL</b> prefix in namespace node means NO PREFIX. ""(empty string '\\0') can be used for specifying 

 *   absense of prefix when setting it, however <b>NULL</b> will be stored and returned.

 *

 * - <b>NULL</b> value of namespace URI is legal only with <b>NULL</b> prefix and only met in 

 *   undeclaration of namespace (<i>xmlns=""</i>). <b>""</b> (empty string) can be used too, however it 

 *   will be returned as <b>NULL</b>.

 *

 * - <b>NULL</b> or <b>""</b> namespace <b>URI</b> with non-<b>NULL</b> prefix is illegal acording to the XML specification.

 *

 * - Namespace of a element is <b>default</b> if it is associated with some namespace declaration with <b>NULL</b> prefix.

 *

 * - Elements are never associated with namespace undeclarations (<b>xmlns=""</b>), instead, such elements have no

 *   namespace declaration referred to. 

 *

 * - Attributes do not have <i>default</i> namespace. Even if it is effective at element scope,

 *   default namespace declaration is not applied to element's attributes (according to the XML specification)

 *

 * - Namespace of a node (element or attribute) is <b>undefined</b> if no namespace declaration is

 *   associated with it.

 *

 * - Node with <i>undefined</i> namespace is serialized as having no prefix. In general,

 *   DOM API handles the complexity of namespace declaration handling and creates neccessary

 *   namespace declarations and undeclares default namespace. However, some node-creation methods (e.g. TXmlEngElement::AddNewElementL()) 

 *   do not ensure that created node with undefined namespace (thus, without a prefix) will 

 *   actually treated after serialization as having some <i>default</i> namespace

 *

 *   @note

 *   Namespace nodes that are result of XPath expression have following restrictions:

 *       - they cannot be used as namespace definitions, because they are not part of

 *         the DOM tree, but copies of existing namespace definitions.

 *       - namespace prefix is not available because it is not mandated by DOM Level 3 XPath module API, 

 *         so in returned copies of DOM tree, namespaces prefix strings are not preserved 

 *         and Prefix() returns NULL.

 * 

 * @lib XmlEngineDOM.lib

 * @since S60 v3.1

 */

class TXmlEngNamespace: public TXmlEngNode

{

  public:

    /**

     * Default constructor

     *

     * @since S60 v3.1

     */

	inline TXmlEngNamespace();

    /**

    /**

     * Get namespace URI

     *

     * @since S60 v3.1

     * @return Namespace URI string 

     * @note "" is never returned - it is replaced with NULL

     *

     * For TXmlEngNamespace(NULL) or namespace undeclaration (xmlns=""), which are

     * treatet as <i>undefined namespace</i> returns NULL,

     * otherwise result is not a NULL string and not a "" (empty string).

     */

    IMPORT_C TPtrC8 Uri() const;

    /**

     * Get namespace prefix. 

     *

     * @since S60 v3.1

     * @return prefix that is bound in the namespace declaration

     * or NULL string for default namespace or if no binding exist

     */

    IMPORT_C TPtrC8 Prefix() const;

    /**

     * Check if namespace is default.

     *

     * @since S60 v3.1

     * @return Whether it is a definition of default namespace

     *    TRUE  -- is a default namespace (no prefix)

     *    FALSE -- not a default namespace (bound to prefix) or empty TXmlEngNamespace(NULL) instance

     */

    IMPORT_C TBool IsDefault() const;

	/**

     * Check if namespace is undefined

	 *

     * @since S60 v3.1

     * @return Whether the namespace is undefined

     *

     * A node's namespace is undefined if no namespace declaration associated with it.

     * @note Same as TXmlEngNode::IsNull()

     */

    IMPORT_C TBool IsUndefined() const; 

protected:

    /**

     *   Workaround to avoid misuse of TXmlEngNode::NamespaceUri() method, which should not be

     *   applied to TXmlEngNamespace node. Since the name of the inherited method from TXmlEngNode

     *   is too similar to TXmlEngNamespace::Uri(), NamespaceUri() is disabled for direct

     *   use. 

     *   If NamespaceUri() is called on the TXmlEngNamespace object that is downcasted to TXmlEngNode, then

     *   NamespaceUri()'s result equals to result of Uri() method.

     *

     * @since S60 v3.1

     * @return NULL

     */

	inline TPtrC8 NamespaceUri();

protected:

    /**

     * Constructor

     *

     * @since S60 v3.1

     * @param aPtr Namespace pointer

     */

	inline TXmlEngNamespace(void* aPtr);

    friend class TXmlEngElement;

    friend class TXmlEngNode;

};

#include "xmlengnamespace.inl"

#endif /* XMLENGINE_NAMESPACE_H_INCLUDED */