Class FunctionCall

All Implemented Interfaces:
Serializable, SourceLocator, Container, Expression, InstructionInfoProvider
Direct Known Subclasses:
ExtensionFunctionCall, SystemFunction, UserFunctionCall, XPathFunctionCall

public abstract class FunctionCall extends ComputedExpression
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

    • setFunctionNameCode

      public final void setFunctionNameCode(int nc)
      Set the name code of the function being called
    • getFunctionNameCode

      public final int getFunctionNameCode()
      Get the name code of the function being called
      Returns:
      the name code as recorded in the name pool
    • getNumberOfArguments

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

      public void setArguments(Expression[] args)
      Method called by the expression parser when all arguments have been supplied
    • getArguments

      public Expression[] getArguments()
      Get the expressions supplied as actual arguments to the function
    • simplify

      public Expression simplify(StaticContext env) 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.
      Specified by:
      simplify in interface Expression
      Overrides:
      simplify in class ComputedExpression
      Parameters:
      env - the static context
      Returns:
      the simplified expression
      Throws:
      XPathException - if an error is discovered during expression rewriting
    • simplifyArguments

      protected final Expression simplifyArguments(StaticContext env) throws XPathException
      Simplify the arguments of the function. Called from the simplify() method of each function.
      Returns:
      the result of simplifying the arguments of the expression
      Throws:
      XPathException
    • typeCheck

      public Expression typeCheck(StaticContext env, 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.
      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:
      XPathException
    • optimize

      public Expression optimize(Optimizer opt, StaticContext env, 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.

      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
    • preEvaluate

      public Expression preEvaluate(StaticContext env) 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.
      Throws:
      XPathException
    • promote

      public Expression promote(PromotionOffer offer) throws XPathException
      Promote this expression if possible
      Specified by:
      promote in interface Expression
      Overrides:
      promote in class ComputedExpression
      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(StaticContext env) throws XPathException
      Method supplied by each class of function to check arguments during parsing, when all the argument expressions have been read
      Throws:
      XPathException
    • checkArgumentCount

      protected int checkArgumentCount(int min, int max, StaticContext env) 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
      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
      Specified by:
      iterateSubExpressions in interface Expression
      Overrides:
      iterateSubExpressions in class ComputedExpression
      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
      Specified by:
      replaceSubExpression in interface Container
      Overrides:
      replaceSubExpression in class ComputedExpression
      Parameters:
      original - the original subexpression
      replacement - the replacement subexpression
      Returns:
      true if the original subexpression is found
    • getDisplayName

      public final String getDisplayName(NamePool pool)
      Diagnostic print of expression structure
    • display

      public void display(int level, 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.
      Parameters:
      level - indentation level for this expression
      out - Output destination
      config -