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:

Expression, java.io.Serializable

public class VennExpression

extends net.sf.saxon.expr.BinaryExpression

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

See Also:

Serialized Form

Field Summary
protected  Expression[]	operands
protected  int	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).
void	display(int level, NamePool pool)           Diagnostic print of expression structure
protected  java.lang.String	displayOperator()
boolean	effectiveBooleanValue(XPathContext context)           Get the effective boolean value.
boolean	equals(java.lang.Object other)           Is this expression the same as another expression?
ItemType	getItemType()           Determine the data type of the items returned by this expression
Expression[]	getSubExpressions()           Get the immediate subexpressions of this expression
int	hashCode()           Is this expression the same as another expression?
protected static boolean	isCommutative(int operator)
SequenceIterator	iterate(XPathContext c)           Iterate over the value of the expression.
Expression	promote(PromotionOffer offer)           Promote this expression if possible
void	setDetails(Expression p1, int op, Expression p2)           Identify the two operands and the operator (for use when the default constructor was used)
Expression	simplify()           Simplify the expression

 

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

computeDependencies, computeStaticProperties, dynamicError, evaluateAsString, evaluateItem, getCardinality, getDependencies, getIntrinsicDependencies, getLineNumber, getSourceLocator, getSpecialProperties, markTailFunctionCalls, setLineNumber, typeError

 

Methods inherited from class java.lang.Object

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

 

Field Detail

operands

protected Expression[] operands

operator

protected int operator

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

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 net.sf.saxon.expr.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 net.sf.saxon.expr.BinaryExpression

Returns:

the simplified expression

XPathException

analyze

public Expression analyze(StaticContext env)
                   throws XPathException

Type-check the expression

Specified by:

analyze in interface Expression

Overrides:

analyze in class net.sf.saxon.expr.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

XPathException

hashCode

public int hashCode()

Is this expression the same as another expression?

Overrides:

hashCode in class net.sf.saxon.expr.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

setDetails

public void setDetails(Expression p1,
                       int op,
                       Expression p2)

Identify the two operands and the operator (for use when the default constructor was used)

Parameters:

p1 - the left-hand operand

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

p2 - the right-hand operand

promote

public Expression promote(PromotionOffer offer)
                   throws XPathException

Promote this expression if possible

Specified by:

promote in interface Expression

Overrides:

promote in class ComputedExpression

Parameters:

offer - details of the offer, for example the offer to move expressions that don't depend on the context to an outer level in the containing expression

Returns:

if the offer is not accepted, return this expression unchanged. Otherwise return the result of rewriting the expression to promote this subexpression

Throws:

XPathException - if any error is detected

getSubExpressions

public Expression[] getSubExpressions()

Get the immediate subexpressions of this expression

Specified by:

getSubExpressions in interface Expression

Overrides:

getSubExpressions in class ComputedExpression

Returns:

an array containing the sub-expressions of this expression

isCommutative

protected static boolean isCommutative(int operator)

equals

public boolean equals(java.lang.Object other)

Is this expression the same as another expression?

Overrides:

equals in class java.lang.Object

display

public void display(int level,
                    NamePool pool)

Diagnostic print of expression structure

Parameters:

level - indentation level for this expression

displayOperator

protected java.lang.String displayOperator()