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:

SourceLocator, ComponentInvocation, UserFunctionReference, IdentityComparable, InstructionInfo

public class UserFunctionCall
extends FunctionCall
implements UserFunctionReference, ComponentInvocation

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

Field Summary

Fields

Modifier and Type	Field and Description
static int	FOREIGN_TAIL_CALL
static int	NOT_TAIL_CALL
static int	SELF_TAIL_CALL

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

argument

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

EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD

Constructor Summary

Constructors

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

Method Summary

Methods

Modifier and Type	Method and Description
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
protected int	computeSpecialProperties() Compute the special properties of this expression.
Expression	copy() Copy an expression.
Sequence	dynamicCall(Sequence[] suppliedArguments, XPathContext context) Call the function dynamically.
Sequence[]	evaluateArguments(XPathContext c)
Item	evaluateItem(XPathContext c) Call the function, returning the value as an item.
void	evaluatePendingUpdates(XPathContext context, PendingUpdateList pul) Evaluate an updating expression, adding the results to a Pending Update List.
void	explain(ExpressionPresenter out) Diagnostic print of expression structure.
int[]	getArgumentEvaluationModes() Get the evaluation modes that have been determined for each of the arguments
int	getBindingSlot() Get the binding slot to be used.
int	getConstructType() Get the type of this expression for use in tracing and diagnostics
ExpressionCompiler	getExpressionCompiler() Return the compiler of the UserFunctionCall expression
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().
int	getIntrinsicDependencies() Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions.
ItemType	getItemType() Determine the data type of the expression, if possible
StructuredQName	getObjectName() Get a name identifying the object of the expression, for example a function name, template name, variable name, key name, element name, etc.
Object	getProperty(String name) Get the value of a particular property of the instruction.
SymbolicName	getSymbolicName() Get the symbolic name of the component that this invocation references
Component	getTarget()
boolean	isRecursiveTailCall()
boolean	isTailCall() Determine whether this is a tail call (not necessarily a recursive tail call)
boolean	isUpdatingExpression() Determine whether this is an updating expression as defined in the XQuery update specification
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, ContextItemStaticInfo 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
Expression	promote(PromotionOffer offer, Expression parent) Promote this expression if possible
boolean	replaceOperand(Expression original, Expression replacement) Replace one subexpression by a replacement subexpression
void	setBindingSlot(int slot) Set the binding slot to be used.
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, ContextItemStaticInfo contextInfo) Type-check the expression.

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

addExternalFunctionCallToPathMap, checkArgumentCount, equals, getArguments, getDisplayName, getExpressionName, getNumberOfArguments, hashCode, operands, setArguments, setFunctionName, simplifyArguments, toShortString, toString

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

adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, clearStreamabilityData, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, explain, getCardinality, getColumnNumber, getConfiguration, getContainer, getDependencies, getEvaluationMethod, getHostLanguage, getIntegerBounds, getLineNumber, getLocationId, getPosture, getProperties, getPublicId, getSlotsUsed, getSpecialProperties, getStreamability, getStreamingAdjunct, getSweep, getSystemId, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isIdentical, isSubtreeExpression, isVacuousExpression, makeStreamingAdjunct, operandList, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, setPostureAndSweep, simplify, staticTypeCheck, suppressValidation, toPattern, toStreamingPattern, typeError, unordered

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

NOT_TAIL_CALL

public static final int NOT_TAIL_CALL

See Also:

Constant Field Values

FOREIGN_TAIL_CALL

public static final int FOREIGN_TAIL_CALL

See Also:

Constant Field Values

SELF_TAIL_CALL

public static final int SELF_TAIL_CALL

See Also:

Constant Field Values

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 of the result of the function call

setFunction

public void setFunction(UserFunction compiledFunction)

Create the reference to the function to be called

Specified by:

setFunction in interface UserFunctionReference

Parameters:

compiledFunction - the function being called

setBindingSlot

public void setBindingSlot(int slot)

Set the binding slot to be used. This is the offset within the binding vector of the containing component where the actual target template is to be found. The target function is not held directly in the UserFunctionCall expression itself because it can be overridden in a using package.

Specified by:

setBindingSlot in interface ComponentInvocation

Parameters:

slot - the offset in the binding vector of the containing package where the target template can be found.

getBindingSlot

public int getBindingSlot()

Get the binding slot to be used. This is the offset within the binding vector of the containing component where the actual target template is to be found.

Specified by:

getBindingSlot in interface ComponentInvocation

Returns:

the offset in the binding vector of the containing package where the target template can be found.

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 - if there is a type error

getFunction

public UserFunction getFunction()

Get the function that is being called by this function call

Returns:

the function being called

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()

checkArguments

public void checkArguments(ExpressionVisitor visitor)
                    throws XPathException

Method called during the type checking phase

Specified by:

checkArguments in class FunctionCall

Parameters:

visitor - the expression visitor

Throws:

XPathException - if the arguments are incorrect

getFunctionName

public final StructuredQName getFunctionName()

Get the qualified of the function being called

Overrides:

getFunctionName in class FunctionCall

Returns:

the qualified name

getSymbolicName

public SymbolicName getSymbolicName()

Description copied from interface: ComponentInvocation

Get the symbolic name of the component that this invocation references

Specified by:

getSymbolicName in interface ComponentInvocation

Returns:

the symbolic name of the target component

getTarget

public Component getTarget()

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()

Determine the data type of the expression, if possible

Specified by:

getItemType in class Expression

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

isUpdatingExpression

public boolean isUpdatingExpression()

Determine whether this is an updating expression as defined in the XQuery update specification

Overrides:

isUpdatingExpression in class Expression

Returns:

true if this is an updating expression

computeSpecialProperties

protected int computeSpecialProperties()

Compute the special properties of this expression. These properties are denoted by a bit-significant integer, possible values are in class StaticProperty. The "special" properties are properties other than cardinality and dependencies, and most of them relate to properties of node sequences, for example whether the nodes are in document order.

Overrides:

computeSpecialProperties in class Expression

Returns:

the special properties, as a bit-significant integer

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

Specified by:

computeCardinality in class 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

typeCheck

public Expression typeCheck(ExpressionVisitor visitor,
                   ContextItemStaticInfo contextInfo)
                     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

contextInfo - Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.

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,
                  ContextItemStaticInfo 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)

promote

public Expression promote(PromotionOffer offer,
                 Expression parent)
                   throws XPathException

Promote this expression if possible

Overrides:

promote in class FunctionCall

Parameters:

offer - details of the offer, for example the offer to move expressions that don't depend on the context to an outer level in the containing expression

parent - the containing expression in the expression tree

Returns:

if the offer is not accepted, return this expression unchanged. Otherwise return the result of rewriting the expression to promote this subexpression

Throws:

XPathException - if any error is detected

computeArgumentEvaluationModes

public void computeArgumentEvaluationModes()

Compute the evaluation mode of each argument

replaceOperand

public boolean replaceOperand(Expression original,
                     Expression replacement)

Description copied from class: FunctionCall

Replace one subexpression by a replacement subexpression

Overrides:

replaceOperand in class FunctionCall

Parameters:

original - the original subexpression

replacement - the replacement subexpression

Returns:

true if the original subexpression is found

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 - 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.

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:

NOT_TAIL_CALL if no tail call was found; FOREIGN_TAIL_CALL if a tail call on a different function was found;

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

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)

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

evaluatePendingUpdates

public void evaluatePendingUpdates(XPathContext context,
                          PendingUpdateList pul)
                            throws XPathException

Evaluate an updating expression, adding the results to a Pending Update List. The default implementation of this method, which is used for non-updating expressions, throws an UnsupportedOperationException

Overrides:

evaluatePendingUpdates in class Expression

Parameters:

context - the XPath dynamic evaluation context

pul - the pending update list to which the results should be written

Throws:

XPathException - if evaluation fails

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

evaluateArguments

public Sequence[] evaluateArguments(XPathContext c)
                             throws XPathException

Throws:

XPathException

dynamicCall

public Sequence dynamicCall(Sequence[] 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 - if the function fails with a dynamic error

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

getConstructType

public int getConstructType()

Description copied from class: Expression

Get the type of this expression for use in tracing and diagnostics

Specified by:

getConstructType in interface InstructionInfo

Overrides:

getConstructType in class Expression

Returns:

the type of expression, as enumerated in class Location

getProperty

public Object getProperty(String name)

Description copied from interface: InstructionInfo

Get the value of a particular property of the instruction. Properties of XSLT instructions are generally known by the name of the stylesheet attribute that defines them.

Specified by:

getProperty in interface InstructionInfo

Overrides:

getProperty in class Expression

Parameters:

name - The name of the required property

Returns:

The value of the requested property, or null if the property is not available

getObjectName

public StructuredQName getObjectName()

Description copied from interface: InstructionInfo

Get a name identifying the object of the expression, for example a function name, template name, variable name, key name, element name, etc. This is used only where the name is known statically.

Specified by:

getObjectName in interface InstructionInfo

Overrides:

getObjectName in class Expression

Returns:

the QName of the object declared or manipulated by this instruction or expression

getExpressionCompiler

public ExpressionCompiler getExpressionCompiler()

Return the compiler of the UserFunctionCall expression

Overrides:

getExpressionCompiler in class Expression

Returns:

the relevant ExpressionCompiler