net.sf.saxon.expr
Class InstanceOfExpression

java.lang.Object
  extended bynet.sf.saxon.expr.ComputedExpression
      extended bynet.sf.saxon.expr.UnaryExpression
          extended bynet.sf.saxon.expr.InstanceOfExpression
All Implemented Interfaces:
Container, Expression, InstructionInfoProvider, java.io.Serializable, javax.xml.transform.SourceLocator

public final class InstanceOfExpression
extends UnaryExpression

InstanceOf Expression: implements "Expr instance of data-type"

See Also:
Serialized Form

Field Summary
 
Fields inherited from class net.sf.saxon.expr.UnaryExpression
operand
 
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
InstanceOfExpression(Expression source, SequenceType target)
           
 
Method Summary
 Expression analyze(StaticContext env, ItemType contextItemType)
          Type-check the expression
 int computeCardinality()
          Determine the cardinality
 void display(int level, NamePool pool, java.io.PrintStream out)
          Diagnostic print of expression structure
protected  java.lang.String displayOperator(NamePool pool)
          Give a string representation of the operator for use in diagnostics
 boolean effectiveBooleanValue(XPathContext context)
          Evaluate the expression as a boolean
 boolean equals(java.lang.Object other)
          Is this expression the same as another expression?
 Item evaluateItem(XPathContext context)
          Evaluate the expression
 ItemType getItemType()
          Determine the data type of the result of the InstanceOf expression
 
Methods inherited from class net.sf.saxon.expr.UnaryExpression
computeSpecialProperties, getBaseExpression, hashCode, iterateSubExpressions, promote, simplify
 
Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, dynamicError, dynamicError, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getParentExpression, getPublicId, getSpecialProperties, getSystemId, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, typeError, typeError
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

InstanceOfExpression

public InstanceOfExpression(Expression source,
                            SequenceType target)
Method Detail

analyze

public Expression analyze(StaticContext env,
                          ItemType contextItemType)
                   throws XPathException
Type-check the expression

Specified by:
analyze in interface Expression
Overrides:
analyze in class UnaryExpression
Returns:
the checked expression
Throws:
XPathException

equals

public boolean equals(java.lang.Object other)
Is this expression the same as another expression?

Overrides:
equals in class UnaryExpression

computeCardinality

public int computeCardinality()
Determine the cardinality

Overrides:
computeCardinality in class UnaryExpression

getItemType

public ItemType getItemType()
Determine the data type of the result of the InstanceOf expression

Specified by:
getItemType in interface Expression
Overrides:
getItemType in class UnaryExpression
Returns:
the item type of the items in the result sequence, insofar as this is known statically.

evaluateItem

public Item evaluateItem(XPathContext context)
                  throws XPathException
Evaluate the expression

Specified by:
evaluateItem in interface Expression
Overrides:
evaluateItem in class ComputedExpression
Parameters:
context - The context in which the expression is to be evaluated
Returns:
the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
Throws:
XPathException - if any dynamic error occurs evaluating the expression

effectiveBooleanValue

public boolean effectiveBooleanValue(XPathContext context)
                              throws XPathException
Evaluate the expression as a boolean

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

displayOperator

protected java.lang.String displayOperator(NamePool pool)
Give a string representation of the operator for use in diagnostics

Specified by:
displayOperator in class UnaryExpression
Returns:
the operator, as a string

display

public void display(int level,
                    NamePool pool,
                    java.io.PrintStream out)
Diagnostic print of expression structure

Specified by:
display in interface Expression
Overrides:
display in class UnaryExpression