net.sf.saxon.xpath

Class XPathFunctionCall

Implemented Interfaces:
EvaluableItem, InstructionInfoProvider, SequenceIterable, Serializable, SourceLocator

public class XPathFunctionCall
extends FunctionCall

This class is an expression that calls an external function supplied using the JAXP XPathFunction interface

Field Summary

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

argument

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD, locationId, staticProperties

Constructor Summary

XPathFunctionCall(XPathFunction function)
Default constructor

Method Summary

PathMap.PathMapNodeSet
addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of this expression to a PathMap.
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 supplied
int
computeCardinality()
Determine the cardinality of the result
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.
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)

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

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

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

addToPathMap, adoptChildExpression, checkPermittedContents, computeCardinality, computeDependencies, computeSpecialProperties, computeStaticProperties, copy, display, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, explain, explain, findParentOf, getCardinality, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getItemType, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, iterate, iterateEvents, iterateSubExpressions, markTailFunctionCalls, optimize, process, promote, replaceSubExpression, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, simplify, staticTypeCheck, suppressValidation, toString, typeCheck, typeError

Constructor Details

XPathFunctionCall

public XPathFunctionCall(XPathFunction function)
Default constructor

Method Details

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 interface 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.

call

public 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 arguments
Returns:
The value returned by the extension function

checkArguments

public void checkArguments(ExpressionVisitor visitor)
            throws XPathException
Method called by the expression parser when all arguments have been supplied
Overrides:
checkArguments in interface FunctionCall

computeCardinality

public int computeCardinality()
Determine the cardinality of the result
Overrides:
computeCardinality in interface Expression
Returns:
ZERO_OR_MORE (we don't know)

copy

public Expression copy()
Copy an expression. This makes a deep copy.
Overrides:
copy in interface Expression
Returns:
the copy of the original expression

getIntrinsicDependencies

public int getIntrinsicDependencies()
Determine which aspects of the context the expression depends on. XPath external functions are given no access to context information so they cannot have any dependencies on it.
Overrides:
getIntrinsicDependencies in interface Expression

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.

Overrides:
getItemType in interface Expression
Parameters:
th - the type hierarchy cache
Returns:
the item type

iterate

public SequenceIterator iterate(XPathContext context)
            throws XPathException
Evaluate the function.
Specified by:
iterate in interface SequenceIterable
Overrides:
iterate in interface 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.

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 interface FunctionCall
Parameters:
visitor - an expression visitor