net.sf.saxon.functions
Class ExtensionFunctionCall

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.expr.FunctionCall
          net.sf.saxon.functions.ExtensionFunctionCall

All Implemented Interfaces:

Serializable, SourceLocator, EvaluableItem, SequenceIterable, InstructionInfoProvider

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

Field Summary

Fields inherited from class net.sf.saxon.expr.Expression

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

ExtensionFunctionCall()
Default constructor

Method Summary

PathMap.PathMapNodeSet	addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet) Add a representation of this expression to a PathMap.
void	checkArguments(ExpressionVisitor visitor) Method called by the expression parser when all arguments have been supplied
int	computeCardinality() Compute the static cardinality of this expression
Expression	copy() Copy an expression.
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.
Class	getTargetClass() Get the class containing the method being called
AccessibleObject	getTargetMethod() Get the target method (or field, or constructor) being called
void	init(StructuredQName functionName, Class theClass, AccessibleObject object, Configuration config) Initialization: creates an ExtensionFunctionCall
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 String	toCamelCase(String name, boolean debug, PrintStream diag) Convert a name to camelCase (by removing hyphens and changing the following letter to capitals)

Methods inherited from class net.sf.saxon.expr.FunctionCall

addExternalFunctionCallToPathMap, equals, explain, getArguments, getDisplayName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, optimize, promote, replaceSubExpression, setArguments, setFunctionName, simplify, toString, typeCheck

Methods inherited from class net.sf.saxon.expr.Expression

adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, effectiveBooleanValue, evaluateAsString, evaluateItem, explain, findParentOf, getCardinality, getColumnNumber, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, iterateEvents, markTailFunctionCalls, process, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ExtensionFunctionCall

public ExtensionFunctionCall()

Default constructor

Method Detail

init

public void init(StructuredQName functionName,
                 Class theClass,
                 AccessibleObject object,
                 Configuration config)

Initialization: creates an ExtensionFunctionCall

Parameters:

functionName - the name of the function, for display purposes

theClass - the Java class containing the method to be called

object - the method, field, or constructor of the Java class to be called

config - the Saxon configuration

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 class FunctionCall

Parameters:

visitor - an expression visitor

Returns:

the result of the early evaluation, or the original expression, or potentially a simplified expression

checkArguments

public void checkArguments(ExpressionVisitor visitor)
                    throws XPathException

Method called by the expression parser when all arguments have been supplied

Parameters:

visitor - the expression visitor

Throws:

XPathException

copy

public Expression copy()

Copy an expression. This makes a deep copy.

Specified by:

copy in class Expression

Returns:

the copy of the original expression

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 class Expression

Returns:

a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty

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 class Expression

Parameters:

pathMap - the PathMap to which the expression should be added

pathMapNodeSet -

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.

iterate

public SequenceIterator iterate(XPathContext context)
                         throws XPathException

Evaluate the function.

Specified by:

iterate in interface SequenceIterable

Overrides:

iterate in class Expression

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.

getTargetClass

public Class getTargetClass()

Get the class containing the method being called

Returns:

the class containing the target method

getTargetMethod

public AccessibleObject getTargetMethod()

Get the target method (or field, or constructor) being called

Returns:

the target method, field, or constructor

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 class Expression

Parameters:

th - the type hierarchy cache

Returns:

the item type

computeCardinality

public int computeCardinality()

Description copied from class: Expression

Compute the static cardinality of this expression

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

toCamelCase

public static String toCamelCase(String name,
                                 boolean debug,
                                 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 camelCase

debug - true if tracing is required

diag - the output stream for diagnostic trace output

Returns:

the camelCased name