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/*
* This file is part of the syndication library
*
* Copyright (C) 2006 Frank Osterfeld <osterfeld@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., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#ifndef SYNDICATION_ELEMENTWRAPPER_H
#define SYNDICATION_ELEMENTWRAPPER_H
#include <QtCore/QString>
#include <boost/shared_ptr.hpp>
#include "ksyndication_export.h"
class QDomElement;
template <class T> class QList;
namespace Syndication {
/**
* A wrapper for XML elements. This is the base class for the (lazy) wrappers
* used in the RSS2 and Atom parsers. The wrapped element can be accessed
* via element(). It also contains several helper functions for XML processing.
*
* @author Frank Osterfeld
*/
class SYNDICATION_EXPORT ElementWrapper
{
public:
/**
* creates a element wrapper wrapping a null element.
* isNull() will return @c true for these instances.
*/
ElementWrapper();
/**
* Copy constructor.The instances share the same element.
* @param other the element wrapper to copy
*/
ElementWrapper(const ElementWrapper& other);
/**
* Creates an element wrapper wrapping the DOM element @c element
* @param element the element to wrap
*/
ElementWrapper(const QDomElement& element); // implicit
/**
* destructor
*/
virtual ~ElementWrapper();
/**
* Assigns another element wrapper to this one. Both instances
* share the same wrapped element instance.
*
* @param other the element wrapper to assign
* @return reference to this instance
*/
ElementWrapper& operator=(const ElementWrapper& other);
/**
* compares two wrappers. Two wrappers are equal if and only if
* the wrapped elements are equal.
* @param other another element wrapper to compare to
*/
bool operator==(const ElementWrapper& other) const;
/**
* returns the wrapped resource.
*/
const QDomElement& element() const;
/**
* returns whether the wrapped element is a null element
* @return @c true if isNull() is true for the wrapped element,
* @c false otherwise
*/
bool isNull() const;
/**
* returns the xml:base value to be used for the wrapped element.
* The xml:base attribute establishes the base URI for resolving any
* relative references found in its scope (its own element and all
* descendants). (See also completeURI())
*
* @return the xml:base value, or a null string if not set
*/
QString xmlBase() const;
/**
* returns the xml:lang value to be used for the wrapped element.
* The xml:lang attribute indicates the natural language for its element
* and all descendants.
*
* @return the xml:lang value, or a null string if not set
*/
QString xmlLang() const;
/**
* completes relative URIs with a prefix specified via xml:base.
*
* Example:
* @code
* xml:base="http://www.foo.org/", uri="announcements/bar.html"
* @endcode
*
* is completed to @c http://www.foo.org/announcements/bar.html
*
* See also xmlBase().
*
* @param uri a possibly relative URI
* @return the resolved, absolute URI (using xml:base), if @c uri is
* a relative, valid URI. If @c uri is not valid, absolute, or no
* xml:base is set in the scope of this element, @c uri is returned
* unmodified.
*/
QString completeURI(const QString& uri) const;
/**
* extracts the text from a child element, respecting namespaces. If
* there is more than one child with the same tag name, the first one is
* processed.
* For instance, when the wrapped element is @c <hisElement>:
* @code
* <thisElement>
* <atom:title>Hi there</atom:title>
* </thisElement>
* @endcode
* @code
* extractElementText("http://www.w3.org/2005/Atom", "title")
* @endcode
* will return the text content of @c atom:title, "Hi there".
* (Assuming that "atom" is defined as "http://www.w3.org/2005/Atom")
*
* @param namespaceURI the namespace URI of the element to extract
* @param localName the local name (local within its namespace) of the
* element to extract
* @return the (trimmed) text content of @c localName, or a null string
* if there is no such tag
*/
QString extractElementTextNS(const QString& namespaceURI,
const QString& localName) const;
/**
* extracts the text from a child element, ignoring namespaces. For
* instance, when the wrapped element is @c <thisElement>:
* @code
* <thisElement>
* <title>Hi there</title>
* </thisElement>
* @endcode
* @c extractElementText("title") will return the text content
* of @c title, "Hi there".
*
* @param tagName the name of the element to extract
* @return the (trimmed) text content of @c tagName, or a null string if
* there is no such tag
*/
QString extractElementText(const QString& tagName) const;
/**
* returns all child elements with tag name @c tagName
* Contrary to QDomElement::elementsByTagName() only direct descendents
* are returned.
*
* @param tagName the tag name of the elements to extract
* @return a list of child elements with the given tag name
*/
QList<QDomElement> elementsByTagName(const QString& tagName) const;
/**
* returns the child nodes of the wrapped element as XML.
*
* See childNodesAsXML(const QDomElement& parent) for details
* @return XML serialization of the wrapped element's children
*/
QString childNodesAsXML() const;
/**
* concatenates the XML representations of all children. Example: If
* @c parent is an @c xhtml:body element like
* @code
* <xhtml:body><p>foo</p><blockquote>bar</blockquote></xhtml:body>
* @endcode
* this function returns
* @code
* <p>foo</p><blockquote>bar</blockquote>
* @endcode
*
* namespace and xml:base information are preserved.
*
* @param parent the DOM element whose children should be returned as
* XML
* @return XML serialization of parent's children
*/
static QString childNodesAsXML(const QDomElement& parent);
/**
* returns all child elements with tag name @c tagname
* and namespace URI @c nsURI.
* Contrary to QDomElement::elementsByTagNameNS() only direct
* descendents are returned
*
* @param nsURI the namespace URI
* @param tagName the local name (local within its namespace) of the
* element to search for
* @return a list of child elements with the given namespace URI
* and tag name
*/
QList<QDomElement> elementsByTagNameNS(const QString& nsURI,
const QString& tagName) const;
/**
* searches the direct children of the wrapped element for an element
* with a given namespace and tag name.
*
* @param nsURI the namespace URI
* @param tagName the local name (local within its namespace) of the
* element to search for
* @return the first child element with the given namespace URI and tag
* name, or a null element if no such element was found.
*/
QDomElement firstElementByTagNameNS(const QString& nsURI,
const QString& tagName) const;
/**
* Returns the wrapped element's text or an empty string.
* For more information, see QDomElement::text();
*/
QString text() const;
/**
* Returns the attribute called name. If the attribute does not exist
* defValue is returned.
* (which is a null string by default).
*
* @param name tag name
* @param defValue the default value
*/
QString attribute(const QString& name,
const QString& defValue=QString()) const;
/**
* Returns the attribute with the local @c name localName and the
* namespace URI @c nsURI.
* If the attribute does not exist @c defValue is returned (which is a
* null string by default).
*
* @param nsURI namespace URI
* @param localName local tag name
* @param defValue the default value
*/
QString attributeNS(const QString& nsURI, const QString& localName,
const QString& defValue=QString()) const;
/**
* Returns true if this element has an attribute called @c name;
* otherwise returns @c false.
*
* @param name the attribute name (without namespace)
*/
bool hasAttribute(const QString& name) const;
/**
* Returns true if this element has an attribute with the local name
* localName and the namespace URI nsURI; otherwise returns false.
*
* @param nsURI namespace URI
* @param localName local attribute name
*/
bool hasAttributeNS(const QString& nsURI, const QString& localName) const;
private:
class ElementWrapperPrivate;
boost::shared_ptr<ElementWrapperPrivate> d;
};
} // namespace Syndication
#endif // SYNDICATION_ELEMENTWRAPPER_H
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