net.sf.saxon.expr

Class UserFunctionCall

java.lang.Object

net.sf.saxon.expr.ComputedExpression

net.sf.saxon.expr.FunctionCall

net.sf.saxon.expr.UserFunctionCall

All Implemented Interfaces:

java.io.Serializable, javax.xml.transform.SourceLocator, Container, Expression, InstructionInfoProvider

public class UserFunctionCall
extends FunctionCall
implements InstructionInfoProvider

This class represents a call to a function defined in the stylesheet or query. It is used for all user-defined functions in XQuery, and for a limited class of user-defined functions in XSLT: those that can be reduced to the evaluation of a single expression.

See Also:

Serialized Form

Field Summary

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

argument

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

locationId, staticProperties

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

Constructors

Constructor and Description
UserFunctionCall()

Method Summary

Modifier and Type	Method and Description
void	checkArguments(StaticContext env) Method called during the type checking phase
void	checkFunctionCall(UserFunction compiledFunction, StaticContext env) Check the function call against the declared function signature
void	computeArgumentEvaluationModes()
int	computeCardinality() Determine the cardinality of the result
void	display(int level, java.io.PrintStream out, Configuration config) Diagnostic print of expression structure.
ValueRepresentation	dynamicCall(ValueRepresentation[] suppliedArguments, XPathContext context) Call the function dynamically.
Item	evaluateItem(XPathContext c) Call the function, returning the value as an item.
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
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
SequenceIterator	iterate(XPathContext c) Call the function, returning an iterator over the results.
boolean	markTailFunctionCalls(int nameCode, int arity) Mark tail-recursive calls on stylesheet functions.
Expression	optimize(Optimizer opt, StaticContext env, ItemType contextItemType) Perform optimisation of an expression and its subexpressions.
Expression	preEvaluate(StaticContext env) 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, StaticContext env) Create the reference to the function to be called, and validate for consistency
void	setStaticType(SequenceType type) Set the static type
Expression	simplify(StaticContext env) Simplify the function call
Expression	typeCheck(StaticContext env, ItemType contextItemType) Type-check the expression.

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

checkArgumentCount, getDisplayName, getFunctionNameCode, getNumberOfArguments, iterateSubExpressions, promote, replaceSubExpression, setArguments, setFunctionNameCode, simplifyArguments

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

adoptChildExpression, checkPermittedContents, computeDependencies, computeSpecialProperties, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, getCardinality, getColumnNumber, getConstructType, getDependencies, getExecutable, getHostLanguage, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation, typeError

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

UserFunctionCall

public UserFunctionCall()

Method Detail

setStaticType

public void setStaticType(SequenceType type)

Set the static type

setFunction

public void setFunction(UserFunction compiledFunction,
                        StaticContext env)
                 throws XPathException

Create the reference to the function to be called, and validate for consistency

Throws:

XPathException

checkFunctionCall

public void checkFunctionCall(UserFunction compiledFunction,
                              StaticContext env)
                       throws XPathException

Check the function call against the declared function signature

Throws:

XPathException

getFunction

public UserFunction getFunction()

Get the function that is being called by this function call

setConfirmed

public void setConfirmed(boolean conf)

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

isConfirmed

public boolean isConfirmed()

Determine whether this function call is confirmed

getArguments

public Expression[] getArguments()

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

Overrides:

getArguments in class FunctionCall

checkArguments

public void checkArguments(StaticContext env)
                    throws XPathException

Method called during the type checking phase

Specified by:

checkArguments in class FunctionCall

Throws:

XPathException

preEvaluate

public Expression preEvaluate(StaticContext env)

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

Overrides:

preEvaluate in class FunctionCall

getItemType

public ItemType getItemType(TypeHierarchy th)

Determine the data type of the expression, if possible

Specified by:

getItemType in interface Expression

Parameters:

th -

Returns:

Type.ITEM (meaning not known in advance)

getIntrinsicDependencies

public int getIntrinsicDependencies()

Description copied from class: ComputedExpression

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 ComputedExpression

Returns:

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

computeCardinality

public int computeCardinality()

Determine the cardinality of the result

Specified by:

computeCardinality in class ComputedExpression

simplify

public Expression simplify(StaticContext env)
                    throws XPathException

Simplify the function call

Specified by:

simplify in interface Expression

Overrides:

simplify in class FunctionCall

Parameters:

env - the static context

Returns:

the simplified expression

Throws:

XPathException - if an error is discovered during expression rewriting

typeCheck

public Expression typeCheck(StaticContext env,
                            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.

Specified by:

typeCheck in interface Expression

Overrides:

typeCheck in class FunctionCall

Parameters:

env - the static context of the expression

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:

StaticError - if an error is discovered during this phase (typically a type error)

XPathException

optimize

public Expression optimize(Optimizer opt,
                           StaticContext env,
                           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.

Specified by:

optimize in interface Expression

Overrides:

optimize in class FunctionCall

Parameters:

opt - the optimizer in use. This provides access to supporting functions; it also allows different optimization strategies to be used in different circumstances.

env - the static context of the expression

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:

StaticError - if an error is discovered during this phase (typically a type error)

XPathException

computeArgumentEvaluationModes

public void computeArgumentEvaluationModes()

markTailFunctionCalls

public boolean markTailFunctionCalls(int nameCode,
                                     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 ComputedExpression

Returns:

true 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: ComputedExpression

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.

Specified by:

getImplementationMethod in interface Expression

Overrides:

getImplementationMethod in class ComputedExpression

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 Expression

Overrides:

evaluateItem in class ComputedExpression

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 Expression

Overrides:

iterate in class ComputedExpression

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

Specified by:

process in interface Expression

Overrides:

process in class ComputedExpression

Parameters:

context -

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".

Throws:

XPathException

display

public void display(int level,
                    java.io.PrintStream out,
                    Configuration config)

Description copied from interface: Expression

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

Specified by:

display in interface Expression

Overrides:

display in class FunctionCall

Parameters:

level - indentation level for this expression

out - Output destination

getInstructionInfo

public InstructionInfo getInstructionInfo()

Get diagnostic information about this expression

Specified by:

getInstructionInfo in interface InstructionInfoProvider

Overrides:

getInstructionInfo in class ComputedExpression