src/xmlpatterns/expr/qoptimizationpasses.cpp

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  41
  42 #include "qcommonsequencetypes_p.h"
  43 #include "qoptimizerblocks_p.h"
  44
  45 #include "qoptimizationpasses_p.h"
  46
  47 QT_BEGIN_NAMESPACE
  48
  49 using namespace QPatternist;
  50
  51 OptimizationPass::List OptimizationPasses::comparisonPasses;
  52 OptimizationPass::List OptimizationPasses::forPasses;
  53 OptimizationPass::List OptimizationPasses::ifThenPasses;
  54 OptimizationPass::List OptimizationPasses::notFN;
  55
  56 void OptimizationPasses::Coordinator::init()
  57 {
  58     static bool isInitialized = false; // STATIC DATA
  59
  60     if(isInitialized)
  61         return;
  62
  63     isInitialized = true;
  64
  65     /* Note, below is many of the building blocks re-used in several passes
  66      * in order to reduce memory use. Thus, when changing one building block
  67      * it potentially affects many passes. */
  68
  69     /* ****************************************************** */
  70     /* Rewrite "count(<expr>) ge 1" into "exists(<expr>)" */
  71     OptimizationPass::ExpressionMarker firstFirstChild;
  72     firstFirstChild.append(0);
  73     firstFirstChild.append(0);
  74
  75     ExpressionIdentifier::List geOpIDs;
  76     const ExpressionIdentifier::Ptr countFN(new ByIDIdentifier(Expression::IDCountFN));
  77     geOpIDs.append(countFN);
  78     geOpIDs.append(ExpressionIdentifier::Ptr(new IntegerIdentifier(1)));
  79
  80     QVector<Expression::ID> geMatcher;
  81     geMatcher.append(Expression::IDValueComparison);
  82     geMatcher.append(Expression::IDGeneralComparison);
  83
  84     const ExpressionIdentifier::Ptr ge(new ComparisonIdentifier(geMatcher,
  85                                                                 AtomicComparator::OperatorGreaterOrEqual));
  86
  87     const ExpressionCreator::Ptr existsFN(new ByIDCreator(Expression::IDExistsFN));
  88     const OptimizationPass::Ptr geToExists(new OptimizationPass(ge, geOpIDs, firstFirstChild, existsFN));
  89     comparisonPasses.append(geToExists);
  90     /* ****************************************************** */
  91
  92     /* ****************************************************** */
  93     /* Rewrite "count(<expr>) gt 0" into "exists(<expr>)" */
  94     ExpressionIdentifier::List countAndIntZero;
  95     countAndIntZero.append(countFN);
  96     const ExpressionIdentifier::Ptr zeroInteger(new IntegerIdentifier(0));
  97     countAndIntZero.append(zeroInteger);
  98
  99     const ExpressionIdentifier::Ptr gt(new ComparisonIdentifier(geMatcher,
 100                                                                 AtomicComparator::OperatorGreaterThan));
 101
 102     const OptimizationPass::Ptr gtToExists(new OptimizationPass(gt, countAndIntZero,
 103                                                                 firstFirstChild, existsFN));
 104     comparisonPasses.append(gtToExists);
 105     /* ****************************************************** */
 106
 107     /* ****************************************************** */
 108     /* Rewrite "count(<expr>) ne 0" into "exists(<expr>)" */
 109
 110     const ExpressionIdentifier::Ptr ne(new ComparisonIdentifier(geMatcher,
 111                                                                 AtomicComparator::OperatorNotEqual));
 112     const OptimizationPass::Ptr neToExists(new OptimizationPass(ne, countAndIntZero, firstFirstChild,
 113                                                                 existsFN,
 114                                                                 OptimizationPass::AnyOrder));
 115     comparisonPasses.append(neToExists);
 116     /* ****************************************************** */
 117
 118     /* ****************************************************** */
 119     /* Rewrite "count(<expr>) eq 0" into "empty(<expr>)" */
 120     ExpressionIdentifier::List eqOpIDs;
 121     eqOpIDs.append(countFN);
 122     eqOpIDs.append(zeroInteger);
 123     const ExpressionCreator::Ptr emptyFN(new ByIDCreator(Expression::IDEmptyFN));
 124     const ExpressionIdentifier::Ptr eq(new ComparisonIdentifier(geMatcher,
 125                                                                 AtomicComparator::OperatorEqual));
 126     const OptimizationPass::Ptr eqToEmpty(new OptimizationPass(eq, eqOpIDs, firstFirstChild,
 127                                                                emptyFN,
 128                                                                OptimizationPass::AnyOrder));
 129     comparisonPasses.append(eqToEmpty);
 130
 131     /* ****************************************************** */
 132
 133     /* ****************************************************** */
 134     /* Rewrite "for $var in <expr> return $var" into "<expr>" */
 135     ExpressionIdentifier::List forOps;
 136     OptimizationPass::ExpressionMarker firstChild;
 137     firstChild.append(0);
 138
 139     forOps.append(ExpressionIdentifier::Ptr());
 140     forOps.append(ExpressionIdentifier::Ptr(new ByIDIdentifier(Expression::IDRangeVariableReference)));
 141     const OptimizationPass::Ptr simplifyFor(new OptimizationPass(ExpressionIdentifier::Ptr(), forOps,
 142                                                                  firstChild, ExpressionCreator::Ptr()));
 143     forPasses.append(simplifyFor);
 144     /* ****************************************************** */
 145
 146     /* ****************************************************** */
 147     /* Rewrite "if(<expr>) then true() else false()" to "<expr>" */
 148     OptimizationPass::ExpressionMarker marker;
 149     marker.append(0);
 150
 151     ExpressionIdentifier::List opIDs;
 152     opIDs.append(ExpressionIdentifier::Ptr(new BySequenceTypeIdentifier(
 153                         CommonSequenceTypes::ExactlyOneBoolean)));
 154     opIDs.append(ExpressionIdentifier::Ptr(new BooleanIdentifier(true)));
 155     opIDs.append(ExpressionIdentifier::Ptr(new BooleanIdentifier(false)));
 156
 157     const OptimizationPass::Ptr pass(new OptimizationPass(ExpressionIdentifier::Ptr(), opIDs, marker));
 158     ifThenPasses.append(pass);
 159     /* ****************************************************** */
 160
 161     /* ****************************************************** */
 162     /* Rewrite "not(exists(X))" into "empty(X)" */
 163     ExpressionIdentifier::List idExistsFN;
 164     idExistsFN.append(ExpressionIdentifier::Ptr(new ByIDIdentifier(Expression::IDExistsFN)));
 165
 166     notFN.append(OptimizationPass::Ptr(new OptimizationPass(ExpressionIdentifier::Ptr(),
 167                                                             idExistsFN,
 168                                                             firstFirstChild,
 169                                                             emptyFN)));
 170
 171     /* Rewrite "not(empty(X))" into "exists(X)" */
 172     ExpressionIdentifier::List idEmptyFN;
 173     idEmptyFN.append(ExpressionIdentifier::Ptr(new ByIDIdentifier(Expression::IDEmptyFN)));
 174
 175     notFN.append(OptimizationPass::Ptr(new OptimizationPass(ExpressionIdentifier::Ptr(),
 176                                                             idEmptyFN,
 177                                                             firstFirstChild,
 178                                                             existsFN)));
 179     /* ****************************************************** */
 180 }
 181
 182 QT_END_NAMESPACE