net.sf.saxon.expr
Class SingletonIntersectExpression

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.expr.BinaryExpression
          net.sf.saxon.expr.VennExpression
              net.sf.saxon.expr.SingletonIntersectExpression

All Implemented Interfaces:

Serializable, SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, SequenceIterable, InstructionInfo, Locator

public class SingletonIntersectExpression
extends VennExpression

This expression is equivalent to (A intersect B) in the case where A has cardinality zero-or-one. This is handled as a special case because the standard sort-merge algorithm involves an unnecessary sort on B.

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.Expression

EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, PUSH_SELECTION, staticProperties, WATCH_METHOD

Constructor Summary

SingletonIntersectExpression(Expression p1, int op, Expression p2)
Special case of an intersect expression where the first argument is a singleton

Method Summary

Expression	copy() Copy an expression.
protected String	displayOperator() Display the operator used by this binary expression
boolean	effectiveBooleanValue(XPathContext c) Get the effective boolean value.
String	getExpressionName() Get a name identifying the kind of expression, in terms meaningful to a user.
SequenceIterator	iterate(XPathContext c) Iterate over the value of the expression.

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

computeCardinality, computeSpecialProperties, equals, gatherComponents, getItemType, hashCode, optimize, simplify, typeCheck

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

explain, explainExtraAttributes, getOperands, getOperator, isAssociative, isCommutative, isInverse, iterateSubExpressions, promote, replaceSubExpression, setFlattened, toString

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

addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, evaluateAsString, evaluateItem, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getImplementationMethod, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setLocationId, staticTypeCheck, suppressValidation, typeError

Methods inherited from class java.lang.Object

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

Constructor Detail

SingletonIntersectExpression

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

Special case of an intersect expression where the first argument is a singleton

Parameters:

p1 - the first argument, always a singleton

op - the operator, always Token.INTERSECT

p2 - the second argument

Method Detail

copy

public Expression copy()

Copy an expression. This makes a deep copy.

Overrides:

copy in class VennExpression

Returns:

the copy of the original expression

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 SequenceIterable

Overrides:

iterate in class VennExpression

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 c)
                              throws XPathException

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

Overrides:

effectiveBooleanValue in class VennExpression

Parameters:

c - 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

getExpressionName

public String getExpressionName()

Description copied from class: VennExpression

Get a name identifying the kind of expression, in terms meaningful to a user.

Overrides:

getExpressionName in class VennExpression

Returns:

a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in explain() output displaying the expression.

displayOperator

protected String displayOperator()

Display the operator used by this binary expression

Overrides:

displayOperator in class BinaryExpression

Returns:

String representation of the operator (for diagnostic display only)