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, InstructionInfo, Locator
public class UserFunctionCall extends FunctionCall
This class represents a call to a user-defined function in the stylesheet or query.
See Also:

  • Field Details

  • Constructor Details

    • UserFunctionCall

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

  • Method Details

    • 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()

    • 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

    • 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, ExpressionVisitor.ContextItemType 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, ExpressionVisitor.ContextItemType 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

    • replaceSubExpression

      public boolean replaceSubExpression(Expression original, Expression replacement)
      Description copied from class: FunctionCall
      Replace one subexpression by a replacement subexpression
      Overrides:
      replaceSubExpression 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 ValueRepresentation[] evaluateArguments(XPathContext c) throws XPathException
      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.