Class ExtensionFunctionCall
- 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.ExtensionFunctionCall
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- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,LocationProvider
,SaxonLocator
,EvaluableItem
,SequenceIterable
,InstructionInfo
,org.xml.sax.Locator
public class ExtensionFunctionCall extends FunctionCall
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:
- Serialized Form
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Field Summary
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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 ExtensionFunctionCall()
Default constructor
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description PathMap.PathMapNodeSet
addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of this expression to a PathMap.protected SequenceIterator
call(ValueRepresentation[] argValues, XPathContext context)
Call an extension function previously identified using the bind() method.void
checkArguments(ExpressionVisitor visitor)
Method called by the expression parser when all arguments have been suppliedint
computeCardinality()
Compute the static cardinality of this expressionExpression
copy()
Copy an expression.PJConverter[]
getArgumentConverters()
Get the converters used to convert the arguments from XPath values to Java valuesprotected java.lang.Object
getField(java.lang.reflect.Field field, java.lang.Object instance)
Access a field.int
getIntrinsicDependencies()
Determine which aspects of the context the expression depends on.ItemType
getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible.java.lang.Class[]
getParameterTypes()
Get the types of the argumentsJPConverter
getResultConverter()
Get the converter used to convert the result from a Java object to an XPath valuejava.lang.Class
getReturnClass()
Get the Java class of the value returned by the methodjava.lang.Class
getTargetClass()
Get the class containing the method being calledjava.lang.reflect.AccessibleObject
getTargetMethod()
Get the target method (or field, or constructor) being calledvoid
init(StructuredQName functionName, java.lang.Class theClass, java.lang.reflect.AccessibleObject object, Configuration config)
Initialization: creates an ExtensionFunctionCallprotected java.lang.Object
invokeConstructor(java.lang.reflect.Constructor constructor, java.lang.Object[] params)
Invoke a constructor.protected java.lang.Object
invokeMethod(java.lang.reflect.Method method, java.lang.Object instance, java.lang.Object[] params)
Invoke a method.SequenceIterator
iterate(XPathContext context)
Evaluate the function.Expression
preEvaluate(ExpressionVisitor visitor)
preEvaluate: this method suppresses compile-time evaluation by doing nothing (because the external function might have side-effects and might use the context)static java.lang.String
toCamelCase(java.lang.String name, boolean debug, java.io.PrintStream diag)
Convert a name to camelCase (by removing hyphens and changing the following letter to capitals)Expression
typeCheck(ExpressionVisitor visitor, ItemType contextItemType)
Type-check the expression.-
Methods inherited from class net.sf.saxon.expr.FunctionCall
addExternalFunctionCallToPathMap, checkArgumentCount, equals, explain, getArguments, getDisplayName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, optimize, promote, replaceSubExpression, setArguments, setFunctionName, simplify, simplifyArguments, toString
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Methods inherited from class net.sf.saxon.expr.Expression
adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeSpecialProperties, computeStaticProperties, display, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, evaluatePendingUpdates, explain, findParentOf, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isUpdatingExpression, iterateEvents, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError
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Method Detail
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init
public void init(StructuredQName functionName, java.lang.Class theClass, java.lang.reflect.AccessibleObject object, Configuration config)
Initialization: creates an ExtensionFunctionCall- Parameters:
functionName
- the name 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 calledconfig
- the Saxon configuration
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preEvaluate
public Expression preEvaluate(ExpressionVisitor visitor)
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
- Parameters:
visitor
- an expression visitor- Returns:
- the result of the early evaluation, or the original expression, or potentially a simplified expression
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typeCheck
public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
Description copied from class:FunctionCall
Type-check the expression. This also calls preEvaluate() to evaluate the function if all the arguments are constant; functions that do not require this behavior can override the preEvaluate method.- Overrides:
typeCheck
in classFunctionCall
- 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 to perform necessary run-time type checks, and to perform other type-related optimizations
- Throws:
XPathException
- if an error is discovered during this phase (typically a type error)
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checkArguments
public void checkArguments(ExpressionVisitor visitor) throws XPathException
Method called by the expression parser when all arguments have been supplied- Specified by:
checkArguments
in classFunctionCall
- Parameters:
visitor
- the expression visitor- Throws:
XPathException
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copy
public Expression copy()
Copy an expression. This makes a deep copy.- Specified by:
copy
in classExpression
- Returns:
- the copy of the original expression
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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 classExpression
- 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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addToPathMap
public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited by an expression in a source tree.The default implementation of this method assumes that an expression does no navigation other than the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the same context as the containing expression. The method must be overridden for any expression where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression, and RootExpression (because they perform navigation), and for the doc(), document(), and collection() functions because they create a new navigation root. Implementations also exist for PathExpression and FilterExpression because they have subexpressions that are evaluated in a different context from the calling expression.
- Overrides:
addToPathMap
in classExpression
- Parameters:
pathMap
- the PathMap to which the expression should be addedpathMapNodeSet
- the PathMapNodeSet to which the paths embodied in this expression should be added- Returns:
- the pathMapNode representing the focus established by this expression, in the case where this expression is the first operand of a path expression or filter expression. For an expression that does navigation, it represents the end of the arc in the path map that describes the navigation route. For other expressions, it is the same as the input pathMapNode.
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iterate
public SequenceIterator iterate(XPathContext context) throws XPathException
Evaluate the function.- Specified by:
iterate
in interfaceSequenceIterable
- Overrides:
iterate
in classExpression
- 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
public java.lang.Class getTargetClass()
Get the class containing the method being called- Returns:
- the class containing the target method
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getTargetMethod
public java.lang.reflect.AccessibleObject getTargetMethod()
Get the target method (or field, or constructor) being called- Returns:
- the target method, field, or constructor
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getParameterTypes
public java.lang.Class[] getParameterTypes()
Get the types of the arguments- Returns:
- an array of classes representing the declared types of the arguments to the method or constructor
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call
protected SequenceIterator call(ValueRepresentation[] argValues, XPathContext context) throws XPathException
Call an extension function previously identified using the bind() method. A subclass can override this method.- Parameters:
argValues
- The values of the argumentscontext
- The XPath dynamic evaluation context- Returns:
- The value returned by the extension function
- Throws:
XPathException
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getItemType
public ItemType getItemType(TypeHierarchy th)
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.
- Specified by:
getItemType
in classExpression
- Parameters:
th
- the type hierarchy cache- Returns:
- the item type
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computeCardinality
public int computeCardinality()
Description copied from class:Expression
Compute the static cardinality of this expression- Specified by:
computeCardinality
in classExpression
- Returns:
- the computed cardinality, as one of the values
StaticProperty.ALLOWS_ZERO_OR_ONE
,StaticProperty.EXACTLY_ONE
,StaticProperty.ALLOWS_ONE_OR_MORE
,StaticProperty.ALLOWS_ZERO_OR_MORE
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getReturnClass
public java.lang.Class getReturnClass()
Get the Java class of the value returned by the method- Returns:
- the Java class of the value returned by the method
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getArgumentConverters
public PJConverter[] getArgumentConverters()
Get the converters used to convert the arguments from XPath values to Java values- Returns:
- an array of converters, one per argument
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getResultConverter
public JPConverter getResultConverter()
Get the converter used to convert the result from a Java object to an XPath value- Returns:
- the converter that is used
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invokeConstructor
protected java.lang.Object invokeConstructor(java.lang.reflect.Constructor constructor, java.lang.Object[] params) throws java.lang.InstantiationException, java.lang.IllegalAccessException, java.lang.reflect.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:
java.lang.InstantiationException
- if the invocation throws an InstantiationExceptionjava.lang.IllegalAccessException
- if the invocation throws an IllegalAccessExceptionjava.lang.reflect.InvocationTargetException
- if the invocation throws an InvocationTargetException (which happens when the constructor itself throws an exception)
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invokeMethod
protected java.lang.Object invokeMethod(java.lang.reflect.Method method, java.lang.Object instance, java.lang.Object[] params) throws java.lang.IllegalAccessException, java.lang.reflect.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:
java.lang.IllegalAccessException
- if the invocation throws an IllegalAccessExceptionjava.lang.reflect.InvocationTargetException
- if the invocation throws an InvocationTargetException (which happens when the method itself throws an exception)
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getField
protected java.lang.Object getField(java.lang.reflect.Field field, java.lang.Object instance) throws java.lang.IllegalAccessException
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:
java.lang.IllegalAccessException
- if the invocation throws an IllegalAccessException
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toCamelCase
public static java.lang.String toCamelCase(java.lang.String name, boolean debug, java.io.PrintStream diag)
Convert a name to camelCase (by removing hyphens and changing the following letter to capitals)- Parameters:
name
- the name to be converted to camelCasedebug
- true if tracing is requireddiag
- the output stream for diagnostic trace output- Returns:
- the camelCased name
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