/****************************************************************************

**

** All rights reserved.

** Contact: Nokia Corporation (qt-info@nokia.com)

**

** This file is part of the QtXmlPatterns module of the Qt Toolkit.

**

** $QT_BEGIN_LICENSE:LGPL$

** No Commercial Usage

** This file contains pre-release code and may not be distributed.

** You may use this file in accordance with the terms and conditions

** contained in the Technology Preview License Agreement accompanying

** this package.

**

** GNU Lesser General Public License Usage

** Alternatively, this file may be used under the terms of the GNU Lesser

** General Public License version 2.1 as published by the Free Software

** Foundation and appearing in the file LICENSE.LGPL included in the

** packaging of this file.  Please review the following information to

** ensure the GNU Lesser General Public License version 2.1 requirements

** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.

**

** In addition, as a special exception, Nokia gives you certain additional

** rights.  These rights are described in the Nokia Qt LGPL Exception

** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.

**

** If you have questions regarding the use of this file, please contact

** Nokia at qt-info@nokia.com.

**

**

**

**

**

**

**

**

** $QT_END_LICENSE$

**

****************************************************************************/

#include <QString>

#include "qitem_p.h"

#include "qabstractxmlreceiver_p.h"

#include "qabstractxmlreceiver.h"

QT_BEGIN_NAMESPACE

/*!

  \class QAbstractXmlReceiver

  \brief The QAbstractXmlReceiver class provides a callback interface

         for transforming the output of a QXmlQuery.

  \reentrant

  \since 4.4

  \ingroup xml-tools

  QAbstractXmlReceiver is an abstract base class that provides

  a callback interface for receiving an \l {XQuery Sequence}

  {XQuery sequence}, usually the output of an QXmlQuery, and

  transforming that sequence into a structure of your choosing,

  usually XML. Consider the example:

  \snippet doc/src/snippets/code/src_xmlpatterns_api_qabstractxmlreceiver.cpp 0

  First it constructs a \l {QXmlQuery} {query} that gets the

  first paragraph from document \c index.html. Then it constructs

  an \l {QXmlSerializer} {XML serializer} with the \l {QXmlQuery}

  {query} and \l {QIODevice} {myOutputDevice} (Note the

  \l {QXmlSerializer} {serializer} is an \e {XML receiver},

  ie a subclass of QAbstractXmlReceiver). Finally, it

  \l {QXmlQuery::evaluateTo()} {evaluates} the

  \l {QXmlQuery} {query}, producing an ordered sequence of calls

  to the \l {QXmlSerializer} {serializer's} callback functions.

  The sequence of callbacks transforms the query output to XML

  and writes it to \l {QIODevice} {myOutputDevice}.

  Although the example uses \l {QXmlQuery} to produce the sequence

  of callbacks to functions in QAbstractXmlReceiver, you can call

  the callback functions directly as long as your sequence of

  calls represents a valid \l {XQuery Sequence} {XQuery sequence}.

  \target XQuery Sequence

  \section1 XQuery Sequences

  An XQuery \a sequence is an ordered collection of zero, one,

  or many \e items. Each \e item is either an \e {atomic value}

  or a \e {node}. An \e {atomic value} is a simple data value.

  There are six kinds of \e nodes.

  \list

  \o An \e {Element Node} represents an XML element.

  \o An \e {Attribute Node} represents an XML attribute.

  \o A \e {Document Node} represents an entire XML document.

  \o A \e {Text Node} represents character data (element content).

  \o A \e {Processing Instruction Node} represents an XML

  processing instruction, which is used in an XML document

  to tell the application reading the document to perform

  some action. A typical example is to use a processing

  instruction to tell the application to use a particular

  XSLT stylesheet to display the document.

  \o And a \e {Comment node} represents an XML comment.

  \endlist

  The \e sequence of \e nodes and \e {atomic values} obeys

  the following rules. Note that \e {Namespace Node} refers

  to a special \e {Attribute Node} with name \e {xmlns}.

  \list

  \o Each \e node appears in the \e sequence before its children

  and their descendants appear.

  \o A \e node's descendants appear in the \e sequence before

  any of its siblings appear.

  \o A \e {Document Node} represents an entire document. Zero or

  more \e {Document Nodes} can appear in a \e sequence, but they

  can only be top level items (i.e., a \e {Document Node} can't

  be a child of another \e node.

  \o \e {Namespace Nodes} immediately follow the \e {Element Node}

   with which they are associated.

  \o \e {Attribute Nodes} immediately follow the \e {Namespace Nodes}

   of the element with which they are associated, or...

   \o If there are no \e {Namespace Nodes} following an element, then

   the \e {Attribute Nodes} immediately follow the element.

   \o An \e {atomic value} can only appear as a top level \e item,

   i.e., it can't appear as a child of a \e node.

   \o \e {Processing Instruction Nodes} do not have children, and

   their parent is either a \e {Document Node} or an \e {Element

   Node}.

   \o \e {Comment Nodes} do not have children, and

   their parent is either a \e {Document Node} or an \e {Element

   Node}.

  \endlist

  The \e sequence of \e nodes and \e {atomic values} is sent to

  an QAbstractXmlReceiver (QXmlSerializer in

  the example above) as a sequence of calls to the receiver's

  callback functions. The mapping of callback functions to

  sequence items is as follows.

  \list

  \o startDocument() and endDocument() are called for each

  \e {Document Node} in the \e sequence. endDocument() is not

  called until all the \e {Document Node's} children have

  appeared in the \e sequence.

  \o startElement() and endElement() are called for each

  \e {Element Node}. endElement() is not called until all the

  \e {Element Node's} children have appeared in the \e sequence.

  \o attribute() is called for each \e {Attribute Node}.

  \o comment() is called for each \e {Comment Node}.

  \o characters() is called for each \e {Text Node}.

  \o processingInstruction() is called for each \e {Processing

  Instruction Node}.

  \o namespaceBinding() is called for each \e {Namespace Node}.

  \o atomicValue() is called for each \e {atomic value}.

  \endlist

  For a complete explanation of XQuery sequences, visit

  \l {http://www.w3.org/TR/xpath-datamodel/}{XQuery Data Model}.

  \sa {http://www.w3.org/TR/xpath-datamodel/}{W3C XQuery 1.0 and XPath 2.0 Data Model (XDM)}

  \sa QXmlSerializer

  \sa QXmlResultItems

 */

template<const QXmlNodeModelIndex::Axis axis>

void QAbstractXmlReceiver::sendFromAxis(const QXmlNodeModelIndex &node)

{

    Q_ASSERT(!node.isNull());

    const QXmlNodeModelIndex::Iterator::Ptr it(node.iterate(axis));

    QXmlNodeModelIndex next(it->next());

    while(!next.isNull())

    {

        sendAsNode(next);

        next = it->next();

    }

}

/*!

 \internal

 */

QAbstractXmlReceiver::QAbstractXmlReceiver(QAbstractXmlReceiverPrivate *d)

  : d_ptr(d)

{

}

/*!

  Constructs an abstract xml receiver.

 */

QAbstractXmlReceiver::QAbstractXmlReceiver() : d_ptr(0)

{

}

/*!

  Destroys the xml receiver.

 */

QAbstractXmlReceiver::~QAbstractXmlReceiver()

{

}

/*!

  \fn void QAbstractXmlReceiver::startElement(const QXmlName &name)

  This callback is called when a new element node appears

  in the \l {XQuery Sequence} {sequence}. \a name is the

  valid \l {QXmlName} {name} of the node element.

 */

/*

### Qt 5:

Consider how source locations should be communicated. Maybe every signature

should be extended by adding "qint64 line = -1, qint64 column = -1".

 */

/*!

  \fn void QAbstractXmlReceiver::endElement()

  This callback is called when the end of an element node

  appears in the \l {XQuery Sequence} {sequence}.

*/

/*!

  \fn void QAbstractXmlReceiver::attribute(const QXmlName &name,

                                           const QStringRef &value)

  This callback is called when an attribute node

  appears in the \l {XQuery Sequence} {sequence}.

  \a name is the \l {QXmlName} {attribute name} and

  the \a value string contains the attribute value.

 */

/*!

  \fn void QAbstractXmlReceiver::comment(const QString &value)

  This callback is called when a comment node appears

  in the \l {XQuery Sequence} {sequence}. The \a value

  is the comment text, which must not contain the string

  "--".

 */

/*!

  \fn void QAbstractXmlReceiver::characters(const QStringRef &value)

  This callback is called when a text node appears in the

  \l {XQuery Sequence} {sequence}. The \a value contains

  the text. Adjacent text nodes may not occur in the

  \l {XQuery Sequence} {sequence}, i.e., this callback must not

  be called twice in a row.

 */

/*!

  \fn void QAbstractXmlReceiver::startDocument()

  This callback is called when a document node appears

  in the \l {XQuery Sequence} {sequence}.

 */

/*

### Qt 5:

Change

    virtual void startDocument() = 0;

To:

    virtual void startDocument(const QUrl &uri) = 0;

Such that it allows the document URI to be communicated. The contract would

allow null QUrls.

*/

/*!

  \fn void QAbstractXmlReceiver::endDocument()

  This callback is called when the end of a document node

  appears in the \l {XQuery Sequence} {sequence}.

 */

/*!

  \fn void QAbstractXmlReceiver::processingInstruction(const QXmlName &target,

                                                       const QString &value)

  This callback is called when a processing instruction

  appears in the \l {XQuery Sequence} {sequence}.

  A processing instruction is used in an XML document

  to tell the application reading the document to

  perform some action. A typical example is to use a

  processing instruction to tell the application to use a

  particular XSLT stylesheet to process the document.

  \quotefile doc/src/snippets/patternist/xmlStylesheet.xq

  \a target is the \l {QXmlName} {name} of the processing

  instruction. Its \e prefix and \e {namespace URI} must both

  be empty. Its \e {local name} is the target. In the above

  example, the name is \e {xml-stylesheet}.

  The \a value specifies the action to be taken. Note that

  the \a value must not contain the string "?>". In the above

  example, the \a value is \e{type="test/xsl" href="formatter.xsl}.

  Generally, use of processing instructions should be avoided,

  because they are not namespace aware and in many contexts

  are stripped out anyway. Processing instructions can often

  be replaced with elements from a custom namespace.

 */

/*!

  \fn void QAbstractXmlReceiver::atomicValue(const QVariant &value)

  This callback is called when an atomic value appears in the \l

  {XQuery Sequence} {sequence}. The \a value is a simple \l {QVariant}

  {data value}. It is guaranteed to be \l {QVariant::isValid()}

  {valid}.

 */

/*!

  \fn virtual void QAbstractXmlReceiver::namespaceBinding(const QXmlName &name)

  This callback is called when a namespace binding is in scope of an

  element. A namespace is defined by a URI. In the \l {QXmlName}

  \a name, the value of \l {QXmlName::namespaceUri()} is that URI. The

  value of \l {QXmlName::prefix()} is the prefix that the URI is bound

  to. The local name is insignificant and can be an arbitrary value.

 */

/*!

  \internal

   Treats \a outputItem as a node and calls the appropriate function,

   e.g., attribute() or comment(), depending on its

   QXmlNodeModelIndex::NodeKind.

   This is a helper function that subclasses can use to multiplex

   Nodes received via item().

 */

void QAbstractXmlReceiver::sendAsNode(const QPatternist::Item &outputItem)

{

    Q_ASSERT(outputItem);

    Q_ASSERT(outputItem.isNode());

    const QXmlNodeModelIndex asNode = outputItem.asNode();

    switch(asNode.kind())

    {

        case QXmlNodeModelIndex::Attribute:

        {

            const QString &v = outputItem.stringValue();

            attribute(asNode.name(), QStringRef(&v));

            return;

        }

        case QXmlNodeModelIndex::Element:

        {

            startElement(asNode.name());

            /* First the namespaces, then attributes, then the children. */

            asNode.sendNamespaces(this);

            sendFromAxis<QXmlNodeModelIndex::AxisAttribute>(asNode);

            sendFromAxis<QXmlNodeModelIndex::AxisChild>(asNode);

            endElement();

            return;

        }

        case QXmlNodeModelIndex::Text:

        {

            const QString &v = asNode.stringValue();

            characters(QStringRef(&v));

            return;

        }

        case QXmlNodeModelIndex::ProcessingInstruction:

        {

            processingInstruction(asNode.name(), outputItem.stringValue());

            return;

        }

        case QXmlNodeModelIndex::Comment:

        {

            comment(outputItem.stringValue());

            return;

        }

        case QXmlNodeModelIndex::Document:

        {

            startDocument();

            sendFromAxis<QXmlNodeModelIndex::AxisChild>(asNode);

            endDocument();

            return;

        }

        case QXmlNodeModelIndex::Namespace:

            Q_ASSERT_X(false, Q_FUNC_INFO, "Not implemented");

    }

    Q_ASSERT_X(false, Q_FUNC_INFO,

               QString::fromLatin1("Unknown node type: %1").arg(asNode.kind()).toUtf8().constData());

}

/*!

  \internal

   This function may be called instead of characters() if, and only if,

   \a value consists only of whitespace.

   The caller gurantees that \a value is not empty.

   \e Whitespace refers to a sequence of characters that are either

   spaces, tabs, or newlines, in any order. In other words, not all

   the Unicode whitespace category is considered whitespace here.

   However, there is no guarantee or requirement that whitespaceOnly()

   is called for text nodes containing whitespace only. characters()

   may be called just as well. This is why the default implementation

   for whitespaceOnly() calls characters().

   \sa characters()

 */

void QAbstractXmlReceiver::whitespaceOnly(const QStringRef &value)

{

    Q_ASSERT_X(value.toString().trimmed().isEmpty(), Q_FUNC_INFO,

               "The caller must guarantee only whitespace is passed. Use characters() in other cases.");

    const QString &v = value.toString();

    characters(QStringRef(&v));

}

/*!

  \internal

 */

void QAbstractXmlReceiver::item(const QPatternist::Item &item)

{

    if(item.isNode())

        return sendAsNode(item);

    else

        atomicValue(QPatternist::AtomicValue::toQt(item.asAtomicValue()));

}

/*!

 \fn void QAbstractXmlReceiver::startOfSequence()

 This callback is called once only, right before the

 \l {XQuery Sequence} {sequence} begins.

 */

/*!

  \fn void QAbstractXmlReceiver::endOfSequence()

 This callback is called once only, right after the

 \l {XQuery Sequence} {sequence} ends.

 */

QT_END_NAMESPACE