Class ExecutableFunctionLibrary

java.lang.Object
net.sf.saxon.functions.ExecutableFunctionLibrary
All Implemented Interfaces:
Serializable, FunctionLibrary

public class ExecutableFunctionLibrary extends Object implements FunctionLibrary
An ExecutableFunctionLibrary is a function library that contains definitions of functions for use at run-time. Normally functions are bound at compile-time; however there are various situations in which the information is needed dynamically, for example (a) to support the XSLT function-available() call (in the pathological case where the argument is not known statically), (b) to allow functions to be called from saxon:evaluate(), (c) to allow functions to be called from a debugging breakpoint. The objects actually held in the ExecutableFunctionLibrary are UserFunctionCall objects that have been prepared at compile time. These are function calls that do full dynamic type checking: that is, they are prepared on the basis that the static types of the arguments are all "item()*", meaning that full type checking is needed at run-time.
See Also:
  • Constructor Details

    • ExecutableFunctionLibrary

      public ExecutableFunctionLibrary(Configuration config)
      Create the ExecutableFunctionLibrary
      Parameters:
      config - the Saxon configuration
  • Method Details

    • addFunction

      public void addFunction(UserFunction fn)
      Register a function with the function library
      Parameters:
      fn - the function to be registered
    • getFunctionSignature

      public SequenceType[] getFunctionSignature(StructuredQName functionName, int arity)
      Test whether a function with a given name and arity is available; if so, return its signature. This supports the function-available() function in XSLT; it is also used to support higher-order functions introduced in XQuery 1.1.

      This method may be called either at compile time or at run time. If the function library is to be used only in an XQuery or free-standing XPath environment, this method may throw an UnsupportedOperationException.

      Specified by:
      getFunctionSignature in interface FunctionLibrary
      Parameters:
      functionName - the qualified name of the function being called
      arity - The number of arguments. This is set to -1 in the case of the single-argument function-available() function; in this case the method should return true if there is some function of this name available for calling.
      Returns:
      if a function of this name and arity is available for calling, then the type signature of the function, as an array of sequence types in which the zeroth entry represents the return type; or a zero-length array if the function exists but the signature is not known; or null if the function does not exist
    • bind

      public Expression bind(StructuredQName functionName, Expression[] staticArgs, StaticContext env, Container container) throws XPathException
      Bind a function, given the URI and local parts of the function name, and the list of expressions supplied as arguments. This method is called at compile time.
      Specified by:
      bind in interface FunctionLibrary
      Parameters:
      functionName - The name of the function to be called
      staticArgs - The expressions supplied statically in the function call. The intention is that the static type of the arguments (obtainable via getItemType() and getCardinality() may be used as part of the binding algorithm.
      env - the static evaluation context
      container -
      Returns:
      An object representing the extension function to be called, if one is found; null if no extension function was found matching the required name and arity.
      Throws:
      XPathException - if a function is found with the required name and arity, but the implementation of the function cannot be loaded or used; or if an error occurs while searching for the function; or if this function library "owns" the namespace containing the function call, but no function was found.
    • copy

      public FunctionLibrary copy()
      This method creates a copy of a FunctionLibrary: if the original FunctionLibrary allows new functions to be added, then additions to this copy will not affect the original, or vice versa.
      Specified by:
      copy in interface FunctionLibrary
      Returns:
      a copy of this function library. This must be an instance of the original class.
    • iterateFunctions

      public Iterator<UserFunction> iterateFunctions()
      Iterate over all the functions defined in this function library. The objects returned by the iterator are of class UserFunction
      Returns:
      an iterator delivering the UserFunction objects representing the user-defined functions in a stylesheet or query