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:

Serializable, Expression

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

operands, operator

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

lineNumber, NO_ARGUMENTS, staticProperties

Constructor Summary

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

Method Summary

Expression	analyze(StaticContext env) Type-check the expression
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() 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() Simplify the expression

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

display, displayOperator, equals, getSubExpressions, isCommutative, promote, setDetails

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

computeDependencies, computeStaticProperties, dynamicError, evaluateAsString, evaluateItem, getCardinality, getDependencies, getIntrinsicDependencies, getLineNumber, getSpecialProperties, markTailFunctionCalls, setLineNumber, 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()

Determine the data type of the items returned by this expression

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 ComputedExpression

simplify

public Expression simplify()
                    throws XPathException

Simplify the expression

Specified by:

simplify in interface Expression

Overrides:

simplify in class BinaryExpression

Returns:

the simplified expression

Throws:

XPathException - if an error is discovered during expression rewriting

analyze

public Expression analyze(StaticContext env)
                   throws XPathException

Type-check the expression

Specified by:

analyze in interface Expression

Overrides:

analyze in class BinaryExpression

Parameters:

env - the static context of the expression

Returns:

the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations

Throws:

XPathException - if an error is discovered during this phase (typically a type error)

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