## 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, LocationProvider, SaxonLocator, EvaluableItem, SequenceIterable, InstructionInfo, Locator

    public class UserFunctionCall

extends FunctionCall

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.FunctionCall
`argument`

Fields inherited from class net.sf.saxon.expr.Expression
`EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, PUSH_SELECTION, staticProperties, WATCH_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
`protected int` `computeSpecialProperties()` Compute the special properties of this expression.
`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` `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` `getConstructType()` Get the type of this expression for use in tracing and diagnostics
`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(TypeHierarchy th)` Determine the data type of the expression, if possible
`int` `getLineNumber(long locationId)` Get the line number within the document or module containing a particular location
`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.
`String` `getSystemId(long locationId)` Get the URI of the document or module containing a particular location
`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)
`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, 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
`Expression` `promote(PromotionOffer offer, Expression parent)` Promote this expression if possible
`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, checkArgumentCount, equals, getArguments, getDisplayName, getExpressionName, getNumberOfArguments, hashCode, iterateSubExpressions, replaceSubExpression, setArguments, setFunctionName, simplify, simplifyArguments, toString`

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

`adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, explain, getCardinality, getColumnNumber, getColumnNumber, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getLineNumber, getLocationId, getLocationProvider, getProperties, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isSubtreeExpression, isVacuousExpression, iterateSameFocusSubExpressions, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError`

Methods inherited from class java.lang.Object
`clone, finalize, 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 of the result of the function call

### 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

### 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

### 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`

### 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

### 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,
                                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)

### 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
  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

### 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:
    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

### 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`

### 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

### 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

### getLineNumber

    public int getLineNumber(long locationId)

  Get the line number within the document or module containing a particular location

  Specified by:
    `getLineNumber` in interface `LocationProvider`
  Overrides:
    `getLineNumber` in class `Expression`
  Parameters:
    `locationId` - identifier of the location in question (as passed down the Receiver pipeline)
  Returns:
    the line number within the document or module.

### getSystemId

    public String getSystemId(long locationId)

  Get the URI of the document or module containing a particular location

  Specified by:
    `getSystemId` in interface `LocationProvider`
  Overrides:
    `getSystemId` in class `Expression`
  Parameters:
    `locationId` - identifier of the location in question (as passed down the Receiver pipeline)
  Returns:
    the URI of the document or module.

Copyright (c) 2004-2010 Saxonica Limited. All rights reserved.