com.saxonica.extra
Class GeneralComparisonSA

java.lang.Object
  net.sf.saxon.expr.ComputedExpression
      net.sf.saxon.expr.BinaryExpression
          net.sf.saxon.expr.GeneralComparison
              com.saxonica.extra.GeneralComparisonSA

All Implemented Interfaces:

Container, Expression, InstructionInfoProvider, java.io.Serializable, javax.xml.transform.SourceLocator

public class GeneralComparisonSA

extends GeneralComparison

This class provides an implementation of the GeneralComparison "=" operator, which deals efficiently with comparing two sequences.

See Also:

Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.expr.GeneralComparison

comparer, singletonOperator

Fields inherited from class net.sf.saxon.expr.BinaryExpression

operand0, operand1, operator

Fields inherited from class net.sf.saxon.expr.ComputedExpression

locationId, staticProperties

Fields inherited from interface net.sf.saxon.expr.Expression

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

GeneralComparisonSA(Expression p0, int op, Expression p1)
Create a relational expression identifying the two operands and the operator

Method Summary

boolean	effectiveBooleanValue(XPathContext context) Evaluate the expression in a boolean context
protected GeneralComparison	getInverseComparison()
static boolean	hashJoin(SequenceIterator iter1, SequenceIterator iter2, XPathContext context, AtomicComparer comparer) Implement the XPath "=" operator for comparing two arbitrary sequences.

Methods inherited from class net.sf.saxon.expr.GeneralComparison

compare, computeCardinality, displayOperator, evaluateItem, getItemType, optimize, typeCheck

Methods inherited from class net.sf.saxon.expr.BinaryExpression

computeSpecialProperties, display, equals, getOperands, getOperator, hashCode, isAssociative, isCommutative, isInverse, iterateSubExpressions, promote, simplify

Methods inherited from class net.sf.saxon.expr.ComputedExpression

adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, dynamicError, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, suppressValidation, typeError, typeError

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

GeneralComparisonSA

public GeneralComparisonSA(Expression p0,
                           int op,
                           Expression p1)

Create a relational expression identifying the two operands and the operator

Parameters:

p0 - the left-hand operand

op - the operator, as a token returned by the Tokenizer (e.g. Token.LT)

p1 - the right-hand operand

Method Detail

effectiveBooleanValue

public boolean effectiveBooleanValue(XPathContext context)
                              throws XPathException

Evaluate the expression in a boolean context

Specified by:

effectiveBooleanValue in interface Expression

Overrides:

effectiveBooleanValue in class GeneralComparison

Parameters:

context - the given context for evaluation

Returns:

a boolean representing the result of the numeric comparison of the two operands

Throws:

XPathException

hashJoin

public static boolean hashJoin(SequenceIterator iter1,
                               SequenceIterator iter2,
                               XPathContext context,
                               AtomicComparer comparer)
                        throws XPathException

Implement the XPath "=" operator for comparing two arbitrary sequences. The comparison is true if any item in the first sequence is equal to any item from the second. This implementation uses a hash join algorithm, modified to cater for the fact that untypedAtomic values act as "wild cards". This algorithm does not handle the special rules for backwards compatibility mode, and is not invoked if BCM is in force.

Parameters:

iter1 - The first sequence

iter2 - The second sequence

context - The dynamic context

comparer - The comparer (which embodies the collation to be used)

Returns:

true if there is a pair of values that are equal, false if not

Throws:

XPathException - if there is a pair of non-comparable values, or if an untyped atomic value cannot be cast to the type of the other operand.

getInverseComparison

protected GeneralComparison getInverseComparison()

Overrides:

getInverseComparison in class GeneralComparison