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

**

** 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

** 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.

**

**

**

**

**

**

**

**

** $QT_END_LICENSE$

**

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

//

//  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_SequenceFNs_H

#define Patternist_SequenceFNs_H

#include "qatomiccomparator_p.h"

#include "qcomparisonplatform_p.h"

#include "qliteral_p.h"

#include "qfunctioncall_p.h"

/**

 * @file

 * @short Contains classes implementing the functions found in

 * <a href="http://www.w3.org/TR/xpath-functions/#general-seq-funcs">XQuery 1.0 and

 * XPath 2.0 Functions and Operators, 15.1 General Functions and Operators on Sequences</a>.

 *

 * @todo document that some functions have both eval funcs implented.

 *

 * @ingroup Patternist_functions

 */

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist

{

    /**

     * @short Implements the function <tt>fn:boolean()</tt>.

     *

     * @see EBVExtractor

     * @ingroup Patternist_functions

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

     */

    class BooleanFN : public FunctionCall

    {

    public:

        virtual bool evaluateEBV(const DynamicContext::Ptr &context) const;

        /**

         * If @p reqType is CommonSequenceTypes::EBV, the type check of

         * the operand is returned. Hence, this removes redundant calls

         * to <tt>fn:boolean()</tt>.

         */

        virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,

                                          const SequenceType::Ptr &reqType);

    };

    /**

     * @short Implements the function <tt>fn:index-of()</tt>.

     *

     * @ingroup Patternist_functions

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

     */

    class IndexOfFN : public FunctionCall,

                      public ComparisonPlatform<IndexOfFN, false>

    {

    public:

        inline IndexOfFN() : ComparisonPlatform<IndexOfFN, false>()

        {

        }

        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;

        virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,

                                          const SequenceType::Ptr &reqType);

        inline AtomicComparator::Operator operatorID() const

        {

            return AtomicComparator::OperatorEqual;

        }

    };

    /**

     * @short Implements the functions <tt>fn:exists()</tt> and <tt>fn:empty()</tt>.

     *

     * Existence is a template value class. Appropriate implementations are achieved

     * by instantiating it with either IDExistsFN or IDEmptyFN.

     *

     * @ingroup Patternist_functions

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

     */

    template<const Expression::ID Id>

    class Existence : public FunctionCall

    {

    public:

        virtual bool evaluateEBV(const DynamicContext::Ptr &context) const

        {

            if(Id == IDExistsFN)

                return !m_operands.first()->evaluateSequence(context)->isEmpty();

            else

                return m_operands.first()->evaluateSequence(context)->isEmpty();

        }

        /**

         * Attempts to rewrite to @c false or @c true by looking at the static

         * cardinality of its operand.

         */

        virtual Expression::Ptr compress(const StaticContext::Ptr &context)

        {

            // RVCT doesn't like using template parameter in trinary operator when the trinary operator result is

            // passed directly into another constructor. 

            Q_ASSERT(Id == IDExistsFN || Id == IDEmptyFN);

            const Expression::Ptr me(FunctionCall::compress(context));

            if(me != this)

                return me;

            // RVCT doesn't like using template parameter in trinary operator when the trinary operator result is

            // passed directly into another constructor. 

            Expression::ID tempId = Id;

            const Cardinality myCard((tempId == IDExistsFN) ? Cardinality::oneOrMore() : Cardinality::empty());

            const Cardinality card(m_operands.first()->staticType()->cardinality());

            if(myCard.isMatch(card))

            { /* Since the dynamic type always is narrower than the static type or equal, and that the

                 static type is in scope, it means we will always be true. */

                return wrapLiteral(CommonValues::BooleanTrue, context, this);

            }

            else

            {

                /* Is it even possible to hit? */

                if(myCard.canMatch(card))

                {

                    return me;

                }

                else

                { /* We can never hit. */

                    return wrapLiteral(CommonValues::BooleanFalse, context, this);

                }

            }

        }

    };

    /**

     * @short Implements the function <tt>fn:distinct-values()</tt>.

     *

     * @ingroup Patternist_functions

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

     */

    class DistinctValuesFN : public FunctionCall,

                             public ComparisonPlatform<IndexOfFN, false>

    {

    public:

        inline DistinctValuesFN() : ComparisonPlatform<IndexOfFN, false>()

        {

        }

        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;

        /**

         * Performs necessary type checks, but also implements the optimization

         * of rewriting to its operand if the operand's cardinality is zero-or-one

         * or exactly-one.

         */

        virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,

                                          const SequenceType::Ptr &reqType);

        /**

         * @returns a type whose item type is the type of the first operand, and

         * a cardinality which is non-empty if the first operand's type is non-empty

         * and allows exactly-one. The latter is needed for operands which has the

         * cardinality 2+, since distinct-values possibly removes items from the

         * source sequence.

         */

        virtual SequenceType::Ptr staticType() const;

    protected:

        inline AtomicComparator::Operator operatorID() const

        {

            return AtomicComparator::OperatorEqual;

        }

    };

    /**

     * @short Implements the function <tt>fn:insert-before()</tt>.

     *

     * @todo docs, explain why evaluateSequence and evaluateSingleton is implemented

     *

     * @ingroup Patternist_functions

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

     */

    class InsertBeforeFN : public FunctionCall

    {

    public:

        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;

        virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;

        /**

         * Implements the static enferences rules. The function's static item type

         * is the union type of the first and third argument, and the cardinality is

         * the cardinalities of the two operands added together. For example,

         * insert-before((1, "str"), 1, xs:double(0)) has the static type xs:anyAtomicType+.

         *

         * @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_insert_before">XQuery 1.0

         * and XPath 2.0 Formal Semantics, 7.2.15 The fn:insert-before function</a>

         */

        virtual SequenceType::Ptr staticType() const;

    };

    /**

     * @short Implements the function <tt>fn:remove()</tt>.

     *

     * @ingroup Patternist_functions

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

     */

    class RemoveFN : public FunctionCall

    {

    public:

        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;

        virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;

        /**

         * Implements the static enferences rules, "Since one item may be removed

         * from the sequence, the resulting type is made optional:"

         *

         * <tt>statEnv |-  (FN-URI,"remove")(Type, Type1) : prime(Type) * quantifier(Type)?</tt>

         *

         * However, because Patternist's type system is more fine grained than Formal Semantics,

         * the sequence isn't made optional. Instead its minimum length is reduced with one.

         *

         * @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_remove">XQuery 1.0

         * and XPath 2.0 Formal Semantics, 7.2.11 The fn:remove function</a>

         */

        virtual SequenceType::Ptr staticType() const;

    };

    /**

     * @short Implements the function <tt>fn:reverse()</tt>.

     *

     * @ingroup Patternist_functions

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

     */

    class ReverseFN : public FunctionCall

    {

    public:

        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;

        virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,

                                          const SequenceType::Ptr &reqType);

        /**

         * Formally speaking, the type inference is:

         *

@verbatim

statEnv |-  (FN-URI,"reverse")(Type) : prime(Type) * quantifier(Type)

@endverbatim

         *

         * @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_reverse">XQuery 1.0

         * and XPath 2.0 Formal Semantics, 7.2.12 The fn:reverse function</a>

         * @returns the static type of the function's first argument.

         */

        virtual SequenceType::Ptr staticType() const;

    };

    /**

     * @short Implements the function <tt>fn:subsequence()</tt>.

     *

     * @ingroup Patternist_functions

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

     * @todo Type inference can be made stronger for this function

     */

    class SubsequenceFN : public FunctionCall

    {

    public:

        SubsequenceFN();

        virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const;

        virtual Item evaluateSingleton(const DynamicContext::Ptr &context) const;

        virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,

                                          const SequenceType::Ptr &reqType);

        /**

         * This function implements rewrites the SubsequenceFN instance into an

         * empty sequence if its third argument, the sequence length argument, is

         * evaluated and is effectively equal or less than zero.

         */

        virtual Expression::Ptr compress(const StaticContext::Ptr &context);

        /**

         * Partially implements the static type inference rules.

         *

         * @see <a href="http://www.w3.org/TR/xquery-semantics/#sec_fn_subsequence">XQuery 1.0

         * and XPath 2.0 Formal Semantics, 7.2.13 The fn:subsequence function</a>

         */

        virtual SequenceType::Ptr staticType() const;

    private:

        bool m_hasTypeChecked;

    };

}

QT_END_NAMESPACE

QT_END_HEADER

#endif