Package net.sf.saxon.functions
Class BooleanFn
- java.lang.Object
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- net.sf.saxon.expr.Expression
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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
,LocationProvider
,SaxonLocator
,EvaluableItem
,Negatable
,SequenceIterable
,InstructionInfo
,org.xml.sax.Locator
public class BooleanFn extends SystemFunction implements Negatable
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.Expression
EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties
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Constructor Summary
Constructors Constructor Description BooleanFn()
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description void
checkArguments(ExpressionVisitor visitor)
Static analysis: prevent sorting of the argumentboolean
effectiveBooleanValue(XPathContext c)
Evaluate the effective boolean valueItem
evaluateItem(XPathContext context)
Evaluate the functionboolean
isNegatable(ExpressionVisitor visitor)
Check whether this specific instance of the expression is negatableExpression
negate()
Create an expression that returns the negation of this expressionExpression
optimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.static Expression
rewriteEffectiveBooleanValue(Expression exp, ExpressionVisitor visitor, ItemType contextItemType)
Optimize an expression whose effective boolean value is requiredExpression
simplify(ExpressionVisitor visitor)
Simplify the function call.-
Methods inherited from class net.sf.saxon.functions.SystemFunction
addContextDocumentArgument, addDocToPathMap, computeCardinality, computeSpecialProperties, copy, getDetails, getErrorCodeForTypeErrors, getItemType, getRequiredType, makeSystemFunction, setDetails, useContextItemAsDefault
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Methods inherited from class net.sf.saxon.expr.FunctionCall
addExternalFunctionCallToPathMap, checkArgumentCount, equals, explain, getArguments, getDisplayName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, preEvaluate, promote, replaceSubExpression, setArguments, setFunctionName, simplifyArguments, toString, typeCheck
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Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, dynamicError, evaluateAsString, evaluatePendingUpdates, explain, findParentOf, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isUpdatingExpression, iterate, iterateEvents, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, 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(ExpressionVisitor visitor) 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.- Overrides:
simplify
in classFunctionCall
- Parameters:
visitor
- an expression visitor- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression rewriting
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checkArguments
public void checkArguments(ExpressionVisitor visitor) throws XPathException
Static analysis: prevent sorting of the argument- Overrides:
checkArguments
in classSystemFunction
- Parameters:
visitor
- the expression visitor- Throws:
XPathException
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optimize
public Expression optimize(ExpressionVisitor visitor, 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.
- Overrides:
optimize
in classSystemFunction
- Parameters:
visitor
- an expression visitorcontextItemType
- 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:
XPathException
- if an error is discovered during this phase (typically a type error)
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isNegatable
public boolean isNegatable(ExpressionVisitor visitor)
Check whether this specific instance of the expression is negatable- Specified by:
isNegatable
in interfaceNegatable
- Returns:
- true if it is
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negate
public Expression negate()
Create an expression that returns the negation of this expression
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rewriteEffectiveBooleanValue
public static Expression rewriteEffectiveBooleanValue(Expression exp, ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
Optimize an expression whose effective boolean value is required- Parameters:
exp
- the expression whose EBV is to be evaluatedvisitor
- an expression visitorcontextItemType
- 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
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evaluateItem
public Item evaluateItem(XPathContext context) throws XPathException
Evaluate the function- Specified by:
evaluateItem
in interfaceEvaluableItem
- Overrides:
evaluateItem
in classExpression
- 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- Overrides:
effectiveBooleanValue
in classExpression
- 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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