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

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

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** No Commercial Usage

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** contained in the Technology Preview License Agreement accompanying

** this package.

**

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

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

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

//

//  W A R N I N G

//  -------------

//

// This file is not part of the Qt API.  It exists purely as an

// implementation detail.  This header file may change from version to

// version without notice, or even be removed.

//

// We mean it.

#ifndef Patternist_ExpressionFactory_H

#define Patternist_ExpressionFactory_H

#include <QXmlQuery>

#include "qexpression_p.h"

#include "qtokenizer_p.h"

#include <QSharedData>

#include <QUrl>

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

class QIODevice;

namespace QPatternist

{

    /**

     * @short The central entry point for compiling expressions.

     *

     * @ingroup Patternist_expressions

     * @author Frans Englich <frans.englich@nokia.com>

     */

    class Q_AUTOTEST_EXPORT ExpressionFactory : public QSharedData

    {

    public:

        typedef QExplicitlySharedDataPointer<ExpressionFactory> Ptr;

        /**

         * @short This constructor cannot be synthesized since we

         * use the Q_DISABLE_COPY macro.

         */

        inline ExpressionFactory()

        {

        }

        virtual ~ExpressionFactory()

        {

        }

        enum CompilationStage

        {

            QueryBodyInitial        = 1,

            QueryBodyTypeCheck      = 1 << 1,

            QueryBodyCompression    = 1 << 2,

            UserFunctionTypeCheck   = 1 << 3,

            UserFunctionCompression = 1 << 4,

            GlobalVariableTypeCheck = 1 << 5

        };

        /**

         * Creates a compiled representation of the XPath expression @p expr, with Static

         * Context information supplied via @p context. This is for example whether the expression

         * is an XPath 1.0 or XPath 2.0 expression, or what functions that are available.

         *

         * @p requiredType specifies what type results of the evaluating the expression

         * must match. Passing CommonValues::ZeroOrMoreItems allows anything as result, while

         * passing CommonSequenceTypes::EBV means anything but an Effective %Boolean Value extractable

         * result is a type error, for example.

         *

         * @note An empty @p expr is an invalid XPath expression. It will be reported as such,

         * but it is neverthless the caller's resonsibility to ensure that it's not that(since

         * it is likely invalid already in the medium it was stored).

         */

        virtual Expression::Ptr createExpression(const QString &expr,

                                                 const StaticContext::Ptr &context,

                                                 const QXmlQuery::QueryLanguage lang,

                                                 const SequenceType::Ptr &requiredType,

                                                 const QUrl &queryURI,

                                                 const QXmlName &initialTemplateName);

        virtual Expression::Ptr createExpression(QIODevice *const device,

                                                 const StaticContext::Ptr &context,

                                                 const QXmlQuery::QueryLanguage lang,

                                                 const SequenceType::Ptr &requiredType,

                                                 const QUrl &queryURI,

                                                 const QXmlName &initialTemplateName);

        /**

         * Finds the last paths of a set of paths(if any) and tells the Path

         * so, such that it can generate the code for checking XPTY0018.

         *

         * Must be called before typeCheck() is called on the operand, since

         * the typeCheck() uses the information for type checking.

         */

        static void registerLastPath(const Expression::Ptr &operand);

    protected:

        enum TemplateCompilationStage

        {

            TemplateInitial         = 1,

            TemplateTypeCheck       = 1 << 1,

            TemplateCompress        = 1 << 2

        };

        /**

         * This function is called by createExpression() each time

         * after a pass on the AST has been completed. Under a typical

         * compilation this function is thus called three times: after the initial

         * build, after the Expression::typeCheck() stage, and after

         * Expression::compress(). @p tree is the AST after each pass.

         *

         * This mechanism is currently used for debugging, since it provides a

         * way of introspecting what the compilation process do to the tree. The

         * current implementation do nothing.

         */

        virtual void processTreePass(const Expression::Ptr &tree,

                                     const CompilationStage stage);

        virtual void processTemplateRule(const Expression::Ptr &body,

                                         const TemplatePattern::Ptr &pattern,

                                         const QXmlName &mode,

                                         const TemplateCompilationStage stage);

        virtual void processNamedTemplate(const QXmlName &name,

                                          const Expression::Ptr &tree,

                                          const TemplateCompilationStage stage);

        Expression::Ptr createExpression(const Tokenizer::Ptr &tokenizer,

                                         const StaticContext::Ptr &context,

                                         const QXmlQuery::QueryLanguage lang,

                                         const SequenceType::Ptr &requiredType,

                                         const QUrl &queryURI,

                                         const QXmlName &initialTemplateName);

    private:

        Q_DISABLE_COPY(ExpressionFactory)

    };

}

QT_END_NAMESPACE

QT_END_HEADER

#endif