net.sf.saxon.expr
Class UserFunctionCall

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.expr.FunctionCall
          net.sf.saxon.expr.UserFunctionCall

All Implemented Interfaces:

Serializable, SourceLocator, EvaluableItem, SequenceIterable, InstructionInfoProvider

public class UserFunctionCall
extends FunctionCall
implements InstructionInfoProvider

This class represents a call to a user-defined function in the stylesheet or query.

See Also:

Serialized Form

Field Summary

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

UserFunctionCall()
Create a function call to a user-written function in a query or stylesheet

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 during the type checking phase
void	checkFunctionCall(UserFunction compiledFunction, ExpressionVisitor visitor) Check the function call against the declared function signature
void	computeArgumentEvaluationModes() Compute the evaluation mode of each argument
int	computeCardinality() Determine the cardinality of the result
Expression	copy() Copy an expression.
ValueRepresentation	dynamicCall(ValueRepresentation[] suppliedArguments, XPathContext context) Call the function dynamically.
Item	evaluateItem(XPathContext c) Call the function, returning the value as an item.
void	explain(ExpressionPresenter out) Diagnostic print of expression structure.
int[]	getArgumentEvaluationModes() Get the evaluation modes that have been determined for each of the arguments
Expression[]	getArguments() Get the arguments (the expressions supplied in the function call)
UserFunction	getFunction() Get the function that is being called by this function call
StructuredQName	getFunctionName() Get the qualified of the function being called
int	getImplementationMethod() An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
InstructionInfo	getInstructionInfo() Get diagnostic information about this expression
int	getIntrinsicDependencies() Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions.
ItemType	getItemType(TypeHierarchy th) Determine the data type of the expression, if possible
boolean	isConfirmed() Determine whether this function call is confirmed
boolean	isRecursiveTailCall() Determine whether this is a recursive tail call
boolean	isTailCall() Determine whether this is a tail call (not necessarily a recursive tail call)
SequenceIterator	iterate(XPathContext c) Call the function, returning an iterator over the results.
EventIterator	iterateEvents(XPathContext context) Process the function call in pull mode
int	markTailFunctionCalls(StructuredQName qName, int arity) Mark tail-recursive calls on stylesheet functions.
Expression	optimize(ExpressionVisitor visitor, ItemType contextItemType) Perform optimisation of an expression and its subexpressions.
Expression	preEvaluate(ExpressionVisitor visitor) Pre-evaluate a function at compile time.
void	process(XPathContext context) Process the function call in push mode
void	setConfirmed(boolean conf) Set this function as confirmed (the function being called is known to exist) or not
void	setFunction(UserFunction compiledFunction) Create the reference to the function to be called
void	setStaticType(SequenceType type) Set the static type
Expression	typeCheck(ExpressionVisitor visitor, ItemType contextItemType) Type-check the expression.

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

addExternalFunctionCallToPathMap, equals, getDisplayName, getNumberOfArguments, hashCode, iterateSubExpressions, promote, replaceSubExpression, setArguments, setFunctionName, simplify, toString

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

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

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

UserFunctionCall

public UserFunctionCall()

Create a function call to a user-written function in a query or stylesheet

Method Detail

setStaticType

public void setStaticType(SequenceType type)

Set the static type

Parameters:

type - the static type

setFunction

public void setFunction(UserFunction compiledFunction)

Create the reference to the function to be called

Parameters:

compiledFunction - the function being called

checkFunctionCall

public void checkFunctionCall(UserFunction compiledFunction,
                              ExpressionVisitor visitor)
                       throws XPathException

Check the function call against the declared function signature

Parameters:

compiledFunction - the function being called

visitor - an expression visitor

Throws:

XPathException

getFunction

public UserFunction getFunction()

Get the function that is being called by this function call

Returns:

the function being called

setConfirmed

public void setConfirmed(boolean conf)

Set this function as confirmed (the function being called is known to exist) or not

Parameters:

conf - true if the function being called is known to exist

isConfirmed

public boolean isConfirmed()

Determine whether this function call is confirmed

Returns:

true if the function being called is known to exist

isTailCall

public boolean isTailCall()

Determine whether this is a tail call (not necessarily a recursive tail call)

Returns:

true if this function call is a tail call

isRecursiveTailCall

public boolean isRecursiveTailCall()

Determine whether this is a recursive tail call

Returns:

true if this function call is a recursive tail call

getArguments

public Expression[] getArguments()

Get the arguments (the expressions supplied in the function call)

Overrides:

getArguments in class FunctionCall

Returns:

the actual expressions used as arguments in the function call

checkArguments

public void checkArguments(ExpressionVisitor visitor)
                    throws XPathException

Method called during the type checking phase

Parameters:

visitor - the expression visitor

Throws:

XPathException

getFunctionName

public final StructuredQName getFunctionName()

Get the qualified of the function being called

Overrides:

getFunctionName in class FunctionCall

Returns:

the qualified name

getArgumentEvaluationModes

public int[] getArgumentEvaluationModes()

Get the evaluation modes that have been determined for each of the arguments

Returns:

an array of integers representing the evaluation modes, one for each argument

preEvaluate

public Expression preEvaluate(ExpressionVisitor visitor)

Pre-evaluate a function at compile time. This version of the method suppresses early evaluation by doing nothing.

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

getItemType

public ItemType getItemType(TypeHierarchy th)

Determine the data type of the expression, if possible

Specified by:

getItemType in class Expression

Parameters:

th - the type hierarchy cache

Returns:

Type.ITEM (meaning not known in advance)

getIntrinsicDependencies

public int getIntrinsicDependencies()

Description copied from class: Expression

Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions. For example, position() has an intrinsic dependency on the context position, while (position()+1) does not. The default implementation of the method returns 0, indicating "no dependencies".

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

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

computeCardinality

public int computeCardinality()

Determine the cardinality of the result

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

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 class FunctionCall

Parameters:

visitor - an expression visitor

contextItemType - 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 to Type.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)

optimize

public Expression optimize(ExpressionVisitor visitor,
                           ItemType contextItemType)
                    throws XPathException

Description copied from class: FunctionCall

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 class FunctionCall

Parameters:

visitor - an expression visitor

contextItemType - 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 to Type.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)

computeArgumentEvaluationModes

public void computeArgumentEvaluationModes()

Compute the evaluation mode of each argument

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.

markTailFunctionCalls

public int markTailFunctionCalls(StructuredQName qName,
                                 int arity)

Mark tail-recursive calls on stylesheet functions. This marks the function call as tailRecursive if if is a call to the containing function, and in this case it also returns "true" to the caller to indicate that a tail call was found.

Overrides:

markTailFunctionCalls in class Expression

Parameters:

qName - the name of the function

arity - the arity (number of parameters) of the function

Returns:

0 if no tail call was found; 1 if a tail call on a different function was found; 2 if a tail recursive call was found and if this call accounts for the whole of the value.

getImplementationMethod

public int getImplementationMethod()

Description copied from class: Expression

An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). This method indicates which of these methods is provided directly. The other methods will always be available indirectly, using an implementation that relies on one of the other methods.

Overrides:

getImplementationMethod in class Expression

Returns:

the implementation method, for example Expression.ITERATE_METHOD or Expression.EVALUATE_METHOD or Expression.PROCESS_METHOD

evaluateItem

public Item evaluateItem(XPathContext c)
                  throws XPathException

Call the function, returning the value as an item. This method will be used only when the cardinality is zero or one. If the function is tail recursive, it returns an Object representing the arguments to the next (recursive) call

Specified by:

evaluateItem in interface EvaluableItem

Overrides:

evaluateItem in class Expression

Parameters:

c - 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

iterate

public SequenceIterator iterate(XPathContext c)
                         throws XPathException

Call the function, returning an iterator over the results. (But if the function is tail recursive, it returns an iterator over the arguments of the recursive call)

Specified by:

iterate in interface SequenceIterable

Overrides:

iterate in class Expression

Parameters:

c - supplies the context for evaluation

Returns:

a SequenceIterator that can be used to iterate over the result of the expression

Throws:

XPathException - if any dynamic error occurs evaluating the expression

process

public void process(XPathContext context)
             throws XPathException

Process the function call in push mode

Overrides:

process in class Expression

Parameters:

context - the XPath dynamic context

Throws:

XPathException

iterateEvents

public EventIterator iterateEvents(XPathContext context)
                            throws XPathException

Process the function call in pull mode

Overrides:

iterateEvents in class Expression

Parameters:

context - the XPath dynamic context

Returns:

the result of the expression as an iterator over a sequence of PullEvent objects

Throws:

XPathException

dynamicCall

public ValueRepresentation dynamicCall(ValueRepresentation[] suppliedArguments,
                                       XPathContext context)
                                throws XPathException

Call the function dynamically. For this to be possible, the static arguments of the function call must have been set up as SuppliedParameterReference objects. The actual arguments are placed on the callee's stack, and the type conversion takes place "in situ".

Parameters:

suppliedArguments - the values to be used for the arguments of the function

context - the dynamic evaluation context

Returns:

the result of evaluating the function

Throws:

XPathException

explain

public void explain(ExpressionPresenter out)

Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

Overrides:

explain in class FunctionCall

Parameters:

out - the expression presenter used to display the structure

getInstructionInfo

public InstructionInfo getInstructionInfo()

Get diagnostic information about this expression

Specified by:

getInstructionInfo in interface InstructionInfoProvider

Overrides:

getInstructionInfo in class Expression