Package net.sf.saxon.functions
Class ExtensionFunctionCall
java.lang.Object
net.sf.saxon.expr.ComputedExpression
net.sf.saxon.expr.FunctionCall
net.sf.saxon.functions.ExtensionFunctionCall
- All Implemented Interfaces:
Serializable
,SourceLocator
,Container
,Expression
,InstructionInfoProvider
This class acts as a container for an extension function defined to call a method
in a user-defined class.
Note that the binding of an XPath function call to a Java method is done in
class JavaExtensionLibrary
- See Also:
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Field Summary
Fields inherited from class net.sf.saxon.expr.FunctionCall
argument
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
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
Method called by the expression parser when all arguments have been suppliedint
protected Object
Access a field.int
Determine which aspects of the context the expression depends on.Determine the data type of the expression, if possible.Get the class containing the method being calledGet the target method (or field, or constructor) being calledvoid
init
(int nameCode, Class theClass, AccessibleObject object, Configuration config) Initialization: creates an ExtensionFunctionCallprotected Object
invokeConstructor
(Constructor constructor, Object[] params) Invoke a constructor.protected Object
invokeMethod
(Method method, Object instance, Object[] params) Invoke a method.iterate
(XPathContext context) Evaluate the function.preEvaluate
(StaticContext env) preEvaluate: this method suppresses compile-time evaluation by doing nothing (because the external function might have side-effects and might use the context)boolean
Determine whether this method uses the focus.Methods inherited from class net.sf.saxon.expr.FunctionCall
checkArgumentCount, display, getArguments, getDisplayName, getFunctionNameCode, getNumberOfArguments, iterateSubExpressions, optimize, promote, replaceSubExpression, setArguments, setFunctionNameCode, simplify, simplifyArguments, typeCheck
Methods inherited from class net.sf.saxon.expr.ComputedExpression
adoptChildExpression, checkPermittedContents, computeDependencies, computeSpecialProperties, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation, typeError
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Constructor Details
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ExtensionFunctionCall
public ExtensionFunctionCall()Default constructor
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Method Details
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init
Initialization: creates an ExtensionFunctionCall- Parameters:
nameCode
- the name code of the function, for display purposestheClass
- the Java class containing the method to be calledobject
- the method, field, or constructor of the Java class to be called
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preEvaluate
preEvaluate: this method suppresses compile-time evaluation by doing nothing (because the external function might have side-effects and might use the context)- Overrides:
preEvaluate
in classFunctionCall
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checkArguments
Method called by the expression parser when all arguments have been supplied- Specified by:
checkArguments
in classFunctionCall
- Throws:
XPathException
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getIntrinsicDependencies
public int getIntrinsicDependencies()Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as XPathContext.VARIABLES and XPathContext.CURRENT_NODE- Overrides:
getIntrinsicDependencies
in classComputedExpression
- Returns:
- a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty
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iterate
Evaluate the function.- Specified by:
iterate
in interfaceExpression
- Overrides:
iterate
in classComputedExpression
- Parameters:
context
- The context in which the function is to be evaluated- Returns:
- a Value representing the result of the function.
- Throws:
XPathException
- if the function cannot be evaluated.
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getTargetClass
Get the class containing the method being called -
getTargetMethod
Get the target method (or field, or constructor) being called -
getItemType
Determine the data type of the expression, if possible. All expressions return sequences, in general; this method determines the type of the items within the sequence, assuming that (a) this is known in advance, and (b) it is the same for all items in the sequence.This method will always return a result, though it may be the best approximation that is available at the time.
- Parameters:
th
-- Returns:
- the item type
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computeCardinality
public int computeCardinality()- Specified by:
computeCardinality
in classComputedExpression
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usesFocus
public boolean usesFocus()Determine whether this method uses the focus. True if the first argument is of type XPathContext. -
invokeConstructor
protected Object invokeConstructor(Constructor constructor, Object[] params) throws InstantiationException, IllegalAccessException, InvocationTargetException Invoke a constructor. This method is provided separately so that it can be refined in a subclass. For example, a subclass might perform tracing of calls, or might trap exceptions.- Parameters:
constructor
- The constructor to be invokedparams
- The parameters to be passed to the constructor- Returns:
- The object returned by the constructor
- Throws:
InstantiationException
- if the invocation throws an InstantiationExceptionIllegalAccessException
- if the invocation throws an IllegalAccessExceptionInvocationTargetException
- if the invocation throws an InvocationTargetException (which happens when the constructor itself throws an exception)
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invokeMethod
protected Object invokeMethod(Method method, Object instance, Object[] params) throws IllegalAccessException, InvocationTargetException Invoke a method. This method is provided separately so that it can be refined in a subclass. For example, a subclass might perform tracing of calls, or might trap exceptions.- Parameters:
method
- The method to be invokedinstance
- The object on which the method is to be invoked. This is set to null if the method is static.params
- The parameters to be passed to the method- Returns:
- The object returned by the method
- Throws:
IllegalAccessException
- if the invocation throws an IllegalAccessExceptionInvocationTargetException
- if the invocation throws an InvocationTargetException (which happens when the method itself throws an exception)
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getField
Access a field. This method is provided separately so that it can be refined in a subclass. For example, a subclass might perform tracing of calls, or might trap exceptions.- Parameters:
field
- The field to be retrievedinstance
- The object whose field is to be retrieved. This is set to null if the field is static.- Returns:
- The value of the field
- Throws:
IllegalAccessException
- if the invocation throws an IllegalAccessException
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