Class FunctionCall

java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.FunctionCall
All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, SequenceIterable, InstructionInfo, Locator
Direct Known Subclasses:
ExtensionFunctionCall, SystemFunction, UserFunctionCall, XPathFunctionCall

public abstract class FunctionCall extends Expression
Abstract superclass for calls to system-defined and user-defined functions
See Also:
  • Field Details

    • argument

      protected Expression[] argument
      The array of expressions representing the actual parameters to the function call
  • Constructor Details

    • FunctionCall

      public FunctionCall()
  • Method Details

    • setFunctionName

      public final void setFunctionName(StructuredQName name)
      Set the name of the function being called
      Parameters:
      name - the name of the function
    • getFunctionName

      public StructuredQName getFunctionName()
      Get the qualified of the function being called
      Returns:
      the qualified name
    • getNumberOfArguments

      public final int getNumberOfArguments()
      Determine the number of actual arguments supplied in the function call
      Returns:
      the arity (the number of arguments)
    • setArguments

      public void setArguments(Expression[] args)
      Method called by the expression parser when all arguments have been supplied
      Parameters:
      args - the expressions contained in the argument list of the function call
    • getArguments

      public Expression[] getArguments()
      Get the expressions supplied as actual arguments to the function
      Returns:
      the array of expressions supplied in the argument list of the function call
    • simplify

      public Expression simplify(ExpressionVisitor visitor) throws XPathException
      Simplify the function call. Default method is to simplify each of the supplied arguments and evaluate the function if all are now known.
      Overrides:
      simplify in class Expression
      Parameters:
      visitor - an expression visitor
      Returns:
      the simplified expression
      Throws:
      XPathException - if an error is discovered during expression rewriting
    • simplifyArguments

      protected final Expression simplifyArguments(ExpressionVisitor visitor) throws XPathException
      Simplify the arguments of the function. Called from the simplify() method of each function.
      Parameters:
      visitor - an expression visitor
      Returns:
      the result of simplifying the arguments of the expression
      Throws:
      XPathException
    • typeCheck

      public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
      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 Expression
      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
      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 Expression
      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)
    • preEvaluate

      public Expression preEvaluate(ExpressionVisitor visitor) throws XPathException
      Pre-evaluate a function at compile time. Functions that do not allow pre-evaluation, or that need access to context information, can override this method.
      Parameters:
      visitor - an expression visitor
      Returns:
      the result of the early evaluation, or the original expression, or potentially a simplified expression
      Throws:
      XPathException
    • promote

      public Expression promote(PromotionOffer offer) throws XPathException
      Promote this expression if possible
      Overrides:
      promote in class Expression
      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
    • checkArguments

      protected abstract void checkArguments(ExpressionVisitor visitor) throws XPathException
      Method supplied by each class of function to check arguments during parsing, when all the argument expressions have been read
      Parameters:
      visitor - the expression visitor
      Throws:
      XPathException
    • checkArgumentCount

      protected int checkArgumentCount(int min, int max, ExpressionVisitor visitor) throws XPathException
      Check number of arguments.
      A convenience routine for use in subclasses.
      Parameters:
      min - the minimum number of arguments allowed
      max - the maximum number of arguments allowed
      visitor - an expression visitor
      Returns:
      the actual number of arguments
      Throws:
      XPathException - if the number of arguments is out of range
    • iterateSubExpressions

      public Iterator iterateSubExpressions()
      Get the immediate subexpressions of this expression
      Overrides:
      iterateSubExpressions in class Expression
      Returns:
      an iterator containing the sub-expressions of this expression
    • replaceSubExpression

      public boolean replaceSubExpression(Expression original, Expression replacement)
      Replace one subexpression by a replacement subexpression
      Overrides:
      replaceSubExpression in class Expression
      Parameters:
      original - the original subexpression
      replacement - the replacement subexpression
      Returns:
      true if the original subexpression is found
    • addExternalFunctionCallToPathMap

      public PathMap.PathMapNodeSet addExternalFunctionCallToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodes)
      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.

      Parameters:
      pathMap - the PathMap to which the expression should be added
      pathMapNodes - the node in the PathMap representing the focus at the point where this expression is called. Set to null if this expression appears at the top level, in which case the expression, if it is registered in the path map at all, must create a new path map root.
      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.
    • getDisplayName

      public final String getDisplayName()
      Get the name of the function for display in messages
      Returns:
      the name of the function as a lexical QName
    • toString

      public String toString()
      The toString() method for an expression attempts to give a representation of the expression in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath. In the case of XSLT instructions, the toString() method gives an abstracted view of the syntax
      Overrides:
      toString in class Expression
    • explain

      public void explain(ExpressionPresenter out)
      Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
      Specified by:
      explain in class Expression
      Parameters:
      out - the expression presenter used to display the structure
    • equals

      public boolean equals(Object o)
      Determine whether two expressions are equivalent
      Overrides:
      equals in class Object
    • hashCode

      public int hashCode()
      Get hashCode in support of equals() method
      Overrides:
      hashCode in class Object