net.sf.saxon.functions
Class BooleanFn

java.lang.Object
  |
  +--net.sf.saxon.expr.ComputedExpression
        |
        +--net.sf.saxon.expr.FunctionCall
              |
              +--net.sf.saxon.functions.SystemFunction
                    |
                    +--net.sf.saxon.functions.BooleanFn
All Implemented Interfaces:
Expression, java.io.Serializable

public class BooleanFn
extends SystemFunction

This class supports the XPath functions boolean(), not(), true(), and false()

See Also:
Serialized Form

Field Summary
static int BOOLEAN
           
static int FALSE
           
static int NOT
           
static int TRUE
           
 
Fields inherited from class net.sf.saxon.functions.SystemFunction
operation
 
Fields inherited from class net.sf.saxon.expr.FunctionCall
argument
 
Fields inherited from class net.sf.saxon.expr.ComputedExpression
lineNumber, NO_ARGUMENTS, staticProperties
 
Constructor Summary
BooleanFn()
           
 
Method Summary
 void checkArguments(StaticContext env)
          Static analysis: prevent sorting of the argument
 boolean effectiveBooleanValue(XPathContext c)
          Evaluate the effective boolean value
 Item evaluateItem(XPathContext context)
          Evaluate the function
 
Methods inherited from class net.sf.saxon.functions.SystemFunction
addContextDocumentArgument, computeCardinality, display, getDetails, getItemType, getName, getRequiredType, main, makeSystemFunction, useContextItemAsDefault
 
Methods inherited from class net.sf.saxon.expr.FunctionCall
analyze, checkArgumentCount, getNumberOfArguments, getSubExpressions, preEvaluate, promote, setArguments, simplify, simplifyArguments
 
Methods inherited from class net.sf.saxon.expr.ComputedExpression
computeDependencies, computeSpecialProperties, computeStaticProperties, dynamicError, evaluateAsString, getCardinality, getDependencies, getIntrinsicDependencies, getLineNumber, getSpecialProperties, iterate, markTailFunctionCalls, setLineNumber, typeError
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

BOOLEAN

public static final int BOOLEAN
See Also:
Constant Field Values

NOT

public static final int NOT
See Also:
Constant Field Values

TRUE

public static final int TRUE
See Also:
Constant Field Values

FALSE

public static final int FALSE
See Also:
Constant Field Values
Constructor Detail

BooleanFn

public BooleanFn()
Method Detail

checkArguments

public void checkArguments(StaticContext env)
                    throws XPathException
Static analysis: prevent sorting of the argument

Overrides:
checkArguments in class SystemFunction
XPathException

evaluateItem

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

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 c)
                              throws XPathException
Evaluate the effective boolean value

Specified by:
effectiveBooleanValue in interface Expression
Overrides:
effectiveBooleanValue in class ComputedExpression
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