Package net.sf.saxon.functions
Class BooleanFn
- java.lang.Object
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- net.sf.saxon.expr.ComputedExpression
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- net.sf.saxon.expr.FunctionCall
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- net.sf.saxon.functions.SystemFunction
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- net.sf.saxon.functions.BooleanFn
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- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,Container
,Expression
,InstructionInfoProvider
public class BooleanFn extends SystemFunction
This class supports the XPath functions boolean(), not(), true(), and false()- See Also:
- Serialized Form
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Field Summary
Fields Modifier and Type Field Description static int
BOOLEAN
static int
FALSE
static int
NOT
static int
TRUE
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Fields inherited from class net.sf.saxon.functions.SystemFunction
operation
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Fields inherited from class net.sf.saxon.expr.FunctionCall
argument
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Fields inherited from class net.sf.saxon.expr.ComputedExpression
locationId, staticProperties
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Fields inherited from interface net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
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Constructor Summary
Constructors Constructor Description BooleanFn()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
checkArguments(StaticContext env)
Static analysis: prevent sorting of the argumentboolean
effectiveBooleanValue(XPathContext c)
Evaluate the effective boolean valueItem
evaluateItem(XPathContext context)
Evaluate the functionExpression
optimize(Optimizer opt, StaticContext env, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.Expression
simplify(StaticContext env)
Simplify the function call.-
Methods inherited from class net.sf.saxon.functions.SystemFunction
addContextDocumentArgument, computeCardinality, computeSpecialProperties, display, getDetails, getErrorCodeForTypeErrors, getItemType, getRequiredType, main, makeSystemFunction, setDetails, useContextItemAsDefault
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Methods inherited from class net.sf.saxon.expr.FunctionCall
checkArgumentCount, getArguments, getDisplayName, getFunctionNameCode, getNumberOfArguments, iterateSubExpressions, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionNameCode, simplifyArguments, typeCheck
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Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation, typeError
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Field Detail
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BOOLEAN
public static final int BOOLEAN
- See Also:
- Constant Field Values
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NOT
public static final int NOT
- See Also:
- Constant Field Values
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TRUE
public static final int TRUE
- See Also:
- Constant Field Values
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FALSE
public static final int FALSE
- See Also:
- Constant Field Values
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Method Detail
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simplify
public Expression simplify(StaticContext env) throws XPathException
Simplify the function call. Default method is to simplify each of the supplied arguments and evaluate the function if all are now known.- Specified by:
simplify
in interfaceExpression
- Overrides:
simplify
in classFunctionCall
- Parameters:
env
- the static context- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression rewriting
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checkArguments
public void checkArguments(StaticContext env) throws XPathException
Static analysis: prevent sorting of the argument- Overrides:
checkArguments
in classSystemFunction
- Throws:
XPathException
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optimize
public Expression optimize(Optimizer opt, StaticContext env, ItemType contextItemType) throws XPathException
Perform optimisation of an expression and its subexpressions.This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.
- Specified by:
optimize
in interfaceExpression
- Overrides:
optimize
in classFunctionCall
- Parameters:
opt
- the optimizer in use. This provides access to supporting functions; it also allows different optimization strategies to be used in different circumstances.env
- the static context of the expressioncontextItemType
- the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set toType.ITEM_TYPE
- Returns:
- the original expression, rewritten if appropriate to optimize execution
- Throws:
StaticError
- if an error is discovered during this phase (typically a type error)XPathException
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evaluateItem
public Item evaluateItem(XPathContext context) throws XPathException
Evaluate the function- Specified by:
evaluateItem
in interfaceExpression
- Overrides:
evaluateItem
in classComputedExpression
- 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
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effectiveBooleanValue
public boolean effectiveBooleanValue(XPathContext c) throws XPathException
Evaluate the effective boolean value- Specified by:
effectiveBooleanValue
in interfaceExpression
- Overrides:
effectiveBooleanValue
in classComputedExpression
- 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
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