net.sf.saxon.expr
Class VennExpression

java.lang.Object
  net.sf.saxon.expr.ComputedExpression
      net.sf.saxon.expr.BinaryExpression
          net.sf.saxon.expr.VennExpression

All Implemented Interfaces:

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

public class VennExpression

extends BinaryExpression

An expression representing a nodeset that is a union, difference, or intersection of two other NodeSets

See Also:

Serialized Form

Field Summary

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

VennExpression(Expression p1, int op, Expression p2)
Constructor

Method Summary

int	computeCardinality() Determine the static cardinality of the expression
int	computeSpecialProperties() Get the static properties of this expression (other than its type).
boolean	effectiveBooleanValue(XPathContext context) Get the effective boolean value.
ItemType	getItemType(TypeHierarchy th) Determine the data type of the items returned by this expression
int	hashCode() Is this expression the same as another expression?
SequenceIterator	iterate(XPathContext c) Iterate over the value of the expression.
Expression	simplify(StaticContext env) Simplify the expression
Expression	typeCheck(StaticContext env, ItemType contextItemType) Type-check the expression

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

display, displayOperator, equals, getOperands, getOperator, isAssociative, isCommutative, isInverse, iterateSubExpressions, optimize, promote

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

adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, dynamicError, evaluateAsString, evaluateItem, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, 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

VennExpression

public VennExpression(Expression p1,
                      int op,
                      Expression p2)

Constructor

Parameters:

p1 - the left-hand operand

op - the operator (union, intersection, or difference)

p2 - the right-hand operand

Method Detail

getItemType

public final ItemType getItemType(TypeHierarchy th)

Determine the data type of the items returned by this expression

Parameters:

th -

Returns:

the data type

computeCardinality

public final int computeCardinality()

Determine the static cardinality of the expression

Overrides:

computeCardinality in class BinaryExpression

computeSpecialProperties

public int computeSpecialProperties()

Get the static properties of this expression (other than its type). The result is bit-signficant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.

Overrides:

computeSpecialProperties in class BinaryExpression

Returns:

StaticProperty.NON_CREATIVE. This is overridden for some subclasses.

simplify

public Expression simplify(StaticContext env)
                    throws XPathException

Simplify the expression

Specified by:

simplify in interface Expression

Overrides:

simplify in class BinaryExpression

Returns:

the simplified expression

Throws:

XPathException

typeCheck

public Expression typeCheck(StaticContext env,
                            ItemType contextItemType)
                     throws XPathException

Type-check the expression

Specified by:

typeCheck in interface Expression

Overrides:

typeCheck in class BinaryExpression

Throws:

XPathException

hashCode

public int hashCode()

Is this expression the same as another expression?

Overrides:

hashCode in class BinaryExpression

iterate

public SequenceIterator iterate(XPathContext c)
                         throws XPathException

Iterate over the value of the expression. The result will always be sorted in document order, with duplicates eliminated

Specified by:

iterate in interface Expression

Overrides:

iterate in class ComputedExpression

Parameters:

c - The context for evaluation

Returns:

a SequenceIterator representing the union of the two operands

Throws:

XPathException - if any dynamic error occurs evaluating the expression

effectiveBooleanValue

public boolean effectiveBooleanValue(XPathContext context)
                              throws XPathException

Get the effective boolean value. In the case of a union expression, this is reduced to an OR expression, for efficiency

Specified by:

effectiveBooleanValue in interface Expression

Overrides:

effectiveBooleanValue in class ComputedExpression

Parameters:

context - The context in which the expression is to be evaluated

Returns:

the effective boolean value

Throws:

XPathException - if any dynamic error occurs evaluating the expression