QPatternist::IntegerComparator Class Reference

Compares xs:integer values. More...

#include <qatomiccomparators_p.h>

Inheritance diagram for QPatternist::IntegerComparator:

Public Functions
virtual ComparisonResult	compare (const Item &op1, const AtomicComparator::Operator op, const Item &op2) const
virtual bool	equals (const Item &op1, const Item &op2) const
Public Functions inherited from QPatternist::AtomicComparator
	AtomicComparator ()
virtual	~AtomicComparator ()
Public Functions inherited from QPatternist::AtomicTypeVisitorResult
	AtomicTypeVisitorResult ()
virtual	~AtomicTypeVisitorResult ()
Public Functions inherited from QSharedData
	QSharedData ()
	Constructs a QSharedData object with a reference count of 0. More...
	QSharedData (const QSharedData &)
	Constructs a QSharedData object with reference count 0. More...

Additional Inherited Members
Public Types inherited from QPatternist::AtomicComparator
enum	ComparisonResult { LessThan = 1, Equal = 2, GreaterThan = 4, Incomparable = 8 }
enum	ComparisonType { AsGeneralComparison = 1, AsValueComparison }
enum	Operator {   OperatorEqual = 1, OperatorNotEqual = 1 << 1, OperatorGreaterThan = 1 << 2, OperatorLessThan = 1 << 3,   OperatorLessThanNaNLeast = 1 << 4, OperatorLessThanNaNGreatest = 1 << 5, OperatorGreaterOrEqual = OperatorEqual | OperatorGreaterThan, OperatorLessOrEqual = OperatorEqual | OperatorLessThan }
typedef QFlags< Operator >	Operators
typedef QExplicitlySharedDataPointer< AtomicComparator >	Ptr
Public Types inherited from QPatternist::AtomicTypeVisitorResult
typedef QExplicitlySharedDataPointer< AtomicTypeVisitorResult >	Ptr
Static Public Functions inherited from QPatternist::AtomicComparator
static QString	displayName (const AtomicComparator::Operator op, const ComparisonType type)
Public Variables inherited from QSharedData
QAtomicInt	ref

Detailed Description

Compares xs:integer values.

Author

Frans Englich frans.nosp@m..eng.nosp@m.lich@.nosp@m.noki.nosp@m.a.com

Definition at line 236 of file qatomiccomparators_p.h.

Functions

compare()

AtomicComparator::ComparisonResult IntegerComparator::compare ( const Item &  op1, const AtomicComparator::Operator  op, const Item &  op2  ) const

virtual

Compares op1 and op2 and determines the relationship between the two. This is used for sorting and comparisons. The implementation performs an assert crash, and must therefore be re-implemented if comparing the relevant values should be possible.

Parameters

op1	the first operand
op	the operator. How a comparison is carried out shouldn't depend on what the operator is, but in some cases it is of interest.
op2	the second operand

Consider: xs:unsignedLong("100") > xs:unsignedLong("18446744073709551615")

If we perform math on the values as if they were xsInteger, the right operand overflows, wraps around, and the expression evaluates to false. Hence we have this code to deal with it.

This is runtime code, it would have been better if we had separate AtomicComparator classes for signed and unsigned values, but the changes required to the lookup code are extensive.

Reimplemented from QPatternist::AtomicComparator.

Definition at line 216 of file qatomiccomparators.cpp.

{
    const Numeric *const num1 = o1.as<Numeric>();
    const Numeric *const num2 = o1.as<Numeric>();

    if(num1->isSigned() || num2->isSigned())
    {
        const xsInteger v1 = o1.as<Numeric>()->toInteger();
        const xsInteger v2 = o2.as<Numeric>()->toInteger();

        if(v1 == v2)
            return Equal;
        else if(v1 < v2)
            return LessThan;
        else
            return GreaterThan;
    }
    else
    {
        const qulonglong v1 = o1.as<Numeric>()->toUnsignedInteger();
        const qulonglong v2 = o2.as<Numeric>()->toUnsignedInteger();

        if(v1 == v2)
            return Equal;
        else if(v1 < v2)
            return LessThan;
        else
            return GreaterThan;
    }
}

equals()

bool IntegerComparator::equals ( const Item &  op1, const Item &  op2  ) const

virtual

Determines whether op1 and op2 are equal. It is the same as calling compare() and checking whether the return value is Equal, but since comparison testing is such a common operation, this specialized function exists.

Returns

true if op1 and op2 are equal.

Parameters

op1	the first operand
op2	the second operand

Implements QPatternist::AtomicComparator.

Definition at line 261 of file qatomiccomparators.cpp.

{
    return o1.as<Numeric>()->toInteger() == o2.as<Numeric>()->toInteger();
}

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The documentation for this class was generated from the following files:

• /src/xmlpatterns/data/qatomiccomparators_p.h
• /src/xmlpatterns/data/qatomiccomparators.cpp