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

**

** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).

** 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

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**

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

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** $QT_END_LICENSE$

**

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

//

//  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_VariableDeclaration_H

#define Patternist_VariableDeclaration_H

#include <QSharedData>

#include "qexpression_p.h"

#include "qpatternistlocale_p.h"

#include "qvariablereference_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

template<typename T> class QStack;

namespace QPatternist

{

    /**

     * @short Represents a declared variable. Only used at

     * the compilation stage.

     *

     * @see FunctionArgument

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

     * @ingroup Patternist_expressions

     */

    class VariableDeclaration : public QSharedData

    {

    public:

        typedef QExplicitlySharedDataPointer<VariableDeclaration> Ptr;

        typedef QStack<VariableDeclaration::Ptr> Stack;

        typedef QList<VariableDeclaration::Ptr> List;

        /**

         * @short The key is the variable name.

         */

        typedef QHash<QXmlName, VariableDeclaration::Ptr> Hash;

        enum Type

        {

            RangeVariable,

            ExpressionVariable,

            FunctionArgument,

            PositionalVariable,

            TemplateParameter,

            /**

             * A global variable is always an external variable, but it is

             * cached differently.

             *

             * @see DynamicContext::globalItemCacheCell()

             */

            GlobalVariable,

            /**

             * External variables doesn't use slots, that's a big difference

             * compared to the other types.

             */

            ExternalVariable

        };

        /**

         * Creates a VariableDeclaration.

         *

         * @p sourceExpr and @p seqType may be @c null.

         */

        VariableDeclaration(const QXmlName n,

                            const VariableSlotID varSlot,

                            const Type t,

                            const SequenceType::Ptr &seqType) : name(n)

                                                              , slot(varSlot)

                                                              , type(t)

                                                              , sequenceType(seqType)

                                                              , canSourceRewrite(true)

        {

            Q_ASSERT(!name.isNull());

            Q_ASSERT(t == ExternalVariable || t == TemplateParameter || varSlot > -1);

        }

        inline bool isUsed() const

        {

            return !references.isEmpty();

        }

        inline const Expression::Ptr &expression() const

        {

            return m_expression;

        }

        inline void setExpression(const Expression::Ptr &expr)

        {

            m_expression = expr;

        }

        /**

         * @short Returns how many times this variable is used.

         */

        inline bool usedByMany() const

        {

            return references.count() > 1;

        }

        /**

         * @short Returns @c true if @p list contains @p lookup.

         */

        static bool contains(const VariableDeclaration::List &list,

                             const QXmlName &lookup);

        const QXmlName                  name;

        const VariableSlotID            slot;

        const Type                      type;

        /**

         * The declared type of the variable. What the value might be, depends

         * on the context which VariableDeclaration is used in. Note that

         * sequenceType is hence not in anyway obligated to the type of

         * expression().

         */

        const SequenceType::Ptr         sequenceType;

        VariableReference::List         references;

        /**

         * @short Whether a reference can rewrite itself to expression().

         *

         * The default value is @c true.

         */

        bool canSourceRewrite;

    private:

        Expression::Ptr                 m_expression;

        Q_DISABLE_COPY(VariableDeclaration)

    };

    /**

     * @short Formats @p var appropriately for display.

     *

     * @relates VariableDeclaration

     */

    static inline QString formatKeyword(const VariableDeclaration::Ptr &var,

                                        const NamePool::Ptr &np)

    {

        Q_ASSERT(var);

        Q_ASSERT(np);

        return formatKeyword(np->displayName(var->name));

    }

}

QT_END_NAMESPACE

QT_END_HEADER

#endif