net.sf.saxon.functions

Class BooleanFn

java.lang.Object

net.sf.saxon.om.AbstractItem

net.sf.saxon.functions.AbstractFunction

net.sf.saxon.functions.SystemFunction

net.sf.saxon.functions.BooleanFn

All Implemented Interfaces:

PullEvent, Callable, Function, GroundedValue, Item, Sequence

public class BooleanFn
extends SystemFunction

This class supports the XPath function boolean()

Constructor Summary

Constructors

Constructor and Description
BooleanFn()

Method Summary

Methods

Modifier and Type	Method and Description
BooleanValue	call(XPathContext c, Sequence[] arguments) Invoke the function
ExpressionCompiler	getExpressionCompiler() Return the compiler of the BooleanFn expression
BooleanFnAdjunct	getStreamingAdjunct() Get a class that supports streamed evaluation of this expression
Expression	makeFunctionCall(Expression[] arguments) Make an expression that either calls this function, or that is equivalent to a call on this function
static Expression	rewriteEffectiveBooleanValue(Expression exp, ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) Optimize an expression whose effective boolean value is required.
void	supplyTypeInformation(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType, Expression[] arguments) Method called during static type checking.

Methods inherited from class net.sf.saxon.functions.SystemFunction

equals, export, exportAttributes, getArity, getCardinality, getContextNode, getDescription, getDetails, getErrorCodeForTypeErrors, getFunctionItemType, getFunctionName, getIntegerBounds, getOperandRoles, getRequiredType, getResultItemType, getResultItemType, getRetainedStaticContext, getSpecialProperties, getStaticBaseUriString, importAttributes, makeCall, makeFunction, makeOptimizedFunctionCall, resultIfEmpty, setArity, setDetails, setRetainedStaticContext, typeCheckCaller

Methods inherited from class net.sf.saxon.functions.AbstractFunction

atomize, deepEquals, effectiveBooleanValue, getStringValue, getStringValueCS, isArray, isMap, optimize, simplify, typeCheck

Methods inherited from class net.sf.saxon.om.AbstractItem

getLength, head, itemAt, iterate, reduce, subsequence

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.sf.saxon.om.Function

iterate

Methods inherited from interface net.sf.saxon.om.Item

head

Methods inherited from interface net.sf.saxon.om.GroundedValue

getLength, head, itemAt, reduce, subsequence

Constructor Detail

BooleanFn

public BooleanFn()

Method Detail

supplyTypeInformation

public void supplyTypeInformation(ExpressionVisitor visitor,
                         ContextItemStaticInfo contextItemType,
                         Expression[] arguments)
                           throws XPathException

Description copied from class: SystemFunction

Method called during static type checking. This method may be implemented in subclasses so that functions can take advantage of knowledge of the types of the arguments that will be supplied.

Overrides:

supplyTypeInformation in class SystemFunction

Parameters:

visitor - an expression visitor, providing access to the static context and configuration

contextItemType - information about whether the context item is set, and what its type is

arguments - the expressions appearing as arguments in the function call

Throws:

XPathException

rewriteEffectiveBooleanValue

public static Expression rewriteEffectiveBooleanValue(Expression exp,
                                      ExpressionVisitor visitor,
                                      ContextItemStaticInfo contextItemType)
                                               throws XPathException

Optimize an expression whose effective boolean value is required. It is appropriate to apply this rewrite to any expression whose value will be obtained by calling the Expression.effectiveBooleanValue() method (and not otherwise)

Parameters:

exp - the expression whose EBV is to be evaluated

visitor - an expression visitor

contextItemType - the type of the context item for this expression

Returns:

an expression that returns the EBV of exp, or null if no optimization was possible

Throws:

XPathException - if static errors are found

call

public BooleanValue call(XPathContext c,
                Sequence[] arguments)
                  throws XPathException

Description copied from interface: Function

Invoke the function

Parameters:

c - the XPath dynamic evaluation context

arguments - the actual arguments to be supplied

Returns:

the result of invoking the function

Throws:

XPathException - if a dynamic error occurs within the function

makeFunctionCall

public Expression makeFunctionCall(Expression[] arguments)

Description copied from class: SystemFunction

Make an expression that either calls this function, or that is equivalent to a call on this function

Overrides:

makeFunctionCall in class SystemFunction

Parameters:

arguments - the supplied arguments to the function call

Returns:

either a function call on this function, or an expression that delivers the same result

getExpressionCompiler

public ExpressionCompiler getExpressionCompiler()

Return the compiler of the BooleanFn expression

Overrides:

getExpressionCompiler in class SystemFunction

Returns:

the relevant ExpressionCompiler

getStreamingAdjunct

public BooleanFnAdjunct getStreamingAdjunct()

Get a class that supports streamed evaluation of this expression

Overrides:

getStreamingAdjunct in class SystemFunction

Returns:

the relevant StreamingAdjunct, or null if none is available