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    41 

    42 //

    43 //  W A R N I N G

    44 //  -------------

    45 //

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

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

    48 // version without notice, or even be removed.

    49 //

    50 // We mean it.

    51 

    52 #ifndef Patternist_OptimizationBlocks_H

    53 #define Patternist_OptimizationBlocks_H

    54 

    55 #include "qatomiccomparator_p.h"

    56 #include "qexpression_p.h"

    57 #include "qoptimizerframework_p.h"

    58 

    59 QT_BEGIN_HEADER

    60 

    61 QT_BEGIN_NAMESPACE

    62 

    63 namespace QPatternist

    64 {

    65     /**

    66      * @short Contains a set of common OptimizerPass instances.

    67      *

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

    69      * @ingroup Patternist_expressions

    70      */

    71     namespace OptimizationPasses

    72     {

    73         /**

    74          * A list of OptimizerPass instances that performs the

    75          * following rewrites:

    76          *

    77          * - <tt>count([expr]) ne 0</tt> into <tt>exists([expr])</tt>

    78          * - <tt>count([expr]) != 0</tt> into <tt>exists([expr])</tt>

    79          * - <tt>0 ne count([expr])</tt> into <tt>exists([expr])</tt>

    80          * - <tt>0 != count([expr])</tt> into <tt>exists([expr])</tt>

    81          * - <tt>count([expr]) eq 0</tt> into <tt>empty([expr])</tt>

    82          * - <tt>count([expr]) = 0</tt> into <tt>empty([expr])</tt>

    83          * - <tt>0 eq count([expr])</tt> into <tt>empty([expr])</tt>

    84          * - <tt>0 = count([expr])</tt> into <tt>empty([expr])</tt>

    85          * - <tt>count([expr]) ge 1</tt> into <tt>exists([expr])</tt>

    86          * - <tt>count([expr]) >= 1</tt> into <tt>exists([expr])</tt>

    87          */

    88         extern OptimizationPass::List comparisonPasses;

    89 

    90         /**

    91          * A list of OptimizerPass instances that performs the

    92          * following rewrites:

    93          *

    94          * - <tt>for $var in [expr] return $var</tt> into <tt>[expr]</tt>

    95          */

    96         extern OptimizationPass::List forPasses;

    97 

    98         /**

    99          * A list of OptimizerPass instances that performs the

   100          * following rewrites:

   101          *

   102          * - <tt>if([expr of type xs:boolean]) then true() else false()</tt>

   103          *   into <tt>[expr of type xs:boolean]</tt>

   104          */

   105         extern OptimizationPass::List ifThenPasses;

   106 

   107         /**

   108          * A list of OptimizerPass instances that performs the

   109          * following rewrites:

   110          *

   111          * - <tt>fn:not(fn:exists([expr]))</tt> into <tt>fn:empty([expr])</tt>

   112          * - <tt>fn:not(fn:empty([expr]))</tt> into <tt>fn:exists([expr])</tt>

   113          */

   114         extern OptimizationPass::List notFN;

   115 

   116         /**

   117          * Initializes the data members in the OptimizationPasses namespace.

   118          *

   119          * This class is not supposed to be instantiated, but to be used via its init()

   120          * function. In fact, this class cannot be instantiated.

   121          *

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

   123          */

   124         class Coordinator

   125         {

   126         public:

   127             /**

   128              * Initializes the members in the OptimizationPasses namespace.

   129              */

   130             static void init();

   131 

   132         private:

   133             Q_DISABLE_COPY(Coordinator)

   134             inline Coordinator();

   135         };

   136     }

   137 }

   138 

   139 QT_END_NAMESPACE

   140 

   141 QT_END_HEADER

   142 

   143 #endif