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39 
40 //
41 //  W A R N I N G
42 //  -------------
43 //
44 // This file is not part of the Qt API.  It exists purely as an
45 // implementation detail.  This header file may change from version to
46 // version without notice, or even be removed.
47 //
48 // We mean it.
49 
50 #ifndef Patternist_OptimizationBlocks_H
51 #define Patternist_OptimizationBlocks_H
52 
53 #include <private/qatomiccomparator_p.h>
54 #include <private/qexpression_p.h>
55 #include <private/qoptimizerframework_p.h>
56 
57 QT_BEGIN_NAMESPACE
58 
59 namespace QPatternist
60 {
61     /**
62      * @short Contains a set of common OptimizerPass instances.
63      *
64      * @author Frans englich <frans.englich@nokia.com>
65      * @ingroup Patternist_expressions
66      */
67     namespace OptimizationPasses
68     {
69         /**
70          * A list of OptimizerPass instances that performs the
71          * following rewrites:
72          *
73          * - <tt>count([expr]) ne 0</tt> into <tt>exists([expr])</tt>
74          * - <tt>count([expr]) != 0</tt> into <tt>exists([expr])</tt>
75          * - <tt>0 ne count([expr])</tt> into <tt>exists([expr])</tt>
76          * - <tt>0 != count([expr])</tt> into <tt>exists([expr])</tt>
77          * - <tt>count([expr]) eq 0</tt> into <tt>empty([expr])</tt>
78          * - <tt>count([expr]) = 0</tt> into <tt>empty([expr])</tt>
79          * - <tt>0 eq count([expr])</tt> into <tt>empty([expr])</tt>
80          * - <tt>0 = count([expr])</tt> into <tt>empty([expr])</tt>
81          * - <tt>count([expr]) ge 1</tt> into <tt>exists([expr])</tt>
82          * - <tt>count([expr]) >= 1</tt> into <tt>exists([expr])</tt>
83          */
84         extern OptimizationPass::List comparisonPasses;
85 
86         /**
87          * A list of OptimizerPass instances that performs the
88          * following rewrites:
89          *
90          * - <tt>for $var in [expr] return $var</tt> into <tt>[expr]</tt>
91          */
92         extern OptimizationPass::List forPasses;
93 
94         /**
95          * A list of OptimizerPass instances that performs the
96          * following rewrites:
97          *
98          * - <tt>if([expr of type xs:boolean]) then true() else false()</tt>
99          *   into <tt>[expr of type xs:boolean]</tt>
100          */
101         extern OptimizationPass::List ifThenPasses;
102 
103         /**
104          * A list of OptimizerPass instances that performs the
105          * following rewrites:
106          *
107          * - <tt>fn:not(fn:exists([expr]))</tt> into <tt>fn:empty([expr])</tt>
108          * - <tt>fn:not(fn:empty([expr]))</tt> into <tt>fn:exists([expr])</tt>
109          */
110         extern OptimizationPass::List notFN;
111 
112         /**
113          * Initializes the data members in the OptimizationPasses namespace.
114          *
115          * This class is not supposed to be instantiated, but to be used via its init()
116          * function. In fact, this class cannot be instantiated.
117          *
118          * @author Frans englich <frans.englich@nokia.com>
119          */
120         class Coordinator
121         {
122         public:
123             /**
124              * Initializes the members in the OptimizationPasses namespace.
125              */
126             static void init();
127 
128         private:
129             Q_DISABLE_COPY(Coordinator)
130             inline Coordinator();
131         };
132     }
133 }
134 
135 QT_END_NAMESPACE
136 
137 #endif
138