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## net.sf.saxon.instruct
Class UserFunction

    java.lang.Object
      net.sf.saxon.instruct.Procedure
          net.sf.saxon.instruct.UserFunction

All Implemented Interfaces:
  java.io.Serializable, javax.xml.transform.SourceLocator, LocationProvider, SaxonLocator, Container, InstructionInfo, org.xml.sax.Locator

    public class UserFunction

extends Procedure

This object represents the compiled form of a user-written function (the source can be either an XSLT stylesheet function or an XQuery function).

It is assumed that type-checking, of both the arguments and the results, has been handled at compile time. That is, the expression supplied as the body of the function must be wrapped in code to check or convert the result to the required type, and calls on the function must be wrapped at compile time to check or convert the supplied arguments.

See Also:
  Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.instruct.Procedure
`body`

Constructor Summary
`UserFunction()` Create a user-defined function with no body (the body must be added later)
`UserFunction(Expression body)` Create a user-defined function

Method Summary
`ValueRepresentation` | `call(ValueRepresentation[] actualArgs, Controller controller)` Call this function.
`ValueRepresentation` | `call(ValueRepresentation[] actualArgs, XPathContextMajor context)` Call this function to return a value.
`void` | `callUpdating(ValueRepresentation[] actualArgs, XPathContextMajor context, PendingUpdateList pul)` Call an updating function.
`void` | `computeEvaluationMode()` Determine the preferred evaluation mode for this function
`boolean` | `containsTailCalls()` Determine whether the function contains tail calls (on this or other functions)
`void` | `gatherDirectContributingCallees(java.util.Set result)` Gather the direct contributing callees of this function.
`SequenceType` | `getArgumentType(int n)` Get the required types of an argument to this function
`int` | `getConstructType()` Get the type of construct.
`int` | `getEvaluationMode()` Get the evaluation mode.
`StructuredQName` | `getFunctionName()` Get the function name
`int` | `getNumberOfArguments()` Get the arity of this function
`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.
`UserFunctionParameter[]` | `getParameterDefinitions()` Get the definitions of the declared parameters for this function
`SequenceType` | `getResultType(TypeHierarchy th)` Get the type of value returned by this function
`boolean` | `isMemoFunction()` Ask whether this function is a memo function
`boolean` | `isTailRecursive()` Determine whether the function contains a tail call, calling itself
`boolean` | `isUpdating()` Ask whether this is an updating function (as defined in XQuery Update)
`EventIterator` | `iterateEvents(ValueRepresentation[] actualArgs, XPathContextMajor context)` Call this function in "pull" mode, returning the results as a sequence of PullEvents.
`void` | `process(ValueRepresentation[] actualArgs, XPathContextMajor context)` Call this function in "push" mode, writing the results to the current output destination.
`void` | `setFunctionName(StructuredQName name)` Set the function name
`void` | `setMemoFunction(boolean isMemo)` Mark this function as a memo function (or not)
`void` | `setParameterDefinitions(UserFunctionParameter[] params)` Set the definitions of the declared parameters for this function
`void` | `setResultType(SequenceType resultType)` Set the declared result type of the function
`void` | `setTailRecursive(boolean tailCalls, boolean recursiveTailCalls)` Indicate whether the function contains a tail call
`void` | `setUpdating(boolean isUpdating)` Set whether this is an updating function (as defined in XQuery Update)

Methods inherited from class net.sf.saxon.instruct.Procedure
`getBody, getColumnNumber, getColumnNumber, getExecutable, getHostLanguage, getLineNumber, getLineNumber, getLocationProvider, getProperties, getProperty, getPublicId, getStackFrameMap, getSystemId, getSystemId, replaceSubExpression, setBody, setExecutable, setHostLanguage, setLineNumber, setStackFrameMap, setSystemId`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### UserFunction

    public UserFunction()

  Create a user-defined function with no body (the body must be added later)

### UserFunction

    public UserFunction(Expression body)

  Create a user-defined function

  Parameters:
    `body` - the expression comprising the body of the function, which is evaluated to compute the result of the function

Method Detail

### setFunctionName

    public void setFunctionName(StructuredQName name)

  Set the function name

  Parameters:
    `name` - the function name

### getFunctionName

    public StructuredQName getFunctionName()

  Get the function name

  Returns:
    the function name, as a StructuredQName

### getObjectName

    public 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. This is used only where the name is known statically.

  Returns:
    the QName of the object declared or manipulated by this instruction or expression

### computeEvaluationMode

    public void computeEvaluationMode()

  Determine the preferred evaluation mode for this function

### setParameterDefinitions

    public void setParameterDefinitions(UserFunctionParameter[] params)

  Set the definitions of the declared parameters for this function

  Parameters:
    `params` - an array of parameter definitions

### getParameterDefinitions

    public UserFunctionParameter[] getParameterDefinitions()

  Get the definitions of the declared parameters for this function

  Returns:
    an array of parameter definitions

### setResultType

    public void setResultType(SequenceType resultType)

  Set the declared result type of the function

  Parameters:
    `resultType` - the declared return type

### setTailRecursive

    public void setTailRecursive(boolean tailCalls,
                                 boolean recursiveTailCalls)

  Indicate whether the function contains a tail call

  Parameters:
    `tailCalls` - true if the function contains a tail call (on any function)
    `recursiveTailCalls` - true if the function contains a tail call (on itself)

### containsTailCalls

    public boolean containsTailCalls()

  Determine whether the function contains tail calls (on this or other functions)

  Returns:
    true if the function contains tail calls

### isTailRecursive

    public boolean isTailRecursive()

  Determine whether the function contains a tail call, calling itself

  Returns:
    true if the function contains a directly-recursive tail call

### setUpdating

    public void setUpdating(boolean isUpdating)

  Set whether this is an updating function (as defined in XQuery Update)

  Parameters:
    `isUpdating` - true if this is an updating function

### isUpdating

    public boolean isUpdating()

  Ask whether this is an updating function (as defined in XQuery Update)

  Returns:
    true if this is an updating function

### getResultType

    public SequenceType getResultType(TypeHierarchy th)

  Get the type of value returned by this function

  Parameters:
    `th` - the type hierarchy cache
  Returns:
    the declared result type, or the inferred result type if this is more precise

### getArgumentType

    public SequenceType getArgumentType(int n)

  Get the required types of an argument to this function

  Parameters:
    `n` - identifies the argument in question, starting at 0
  Returns:
    a SequenceType object, indicating the required type of the argument

### getEvaluationMode

    public int getEvaluationMode()

  Get the evaluation mode. The evaluation mode will be computed if this has not already been done

  Returns:
    the computed evaluation mode

### getNumberOfArguments

    public int getNumberOfArguments()

  Get the arity of this function

  Returns:
    the number of arguments

### setMemoFunction

    public void setMemoFunction(boolean isMemo)

  Mark this function as a memo function (or not)

  Parameters:
    `isMemo` - true if this is a memo function

### isMemoFunction

    public boolean isMemoFunction()

  Ask whether this function is a memo function

  Returns:
    true if this function is marked as a memo function

### gatherDirectContributingCallees

    public void gatherDirectContributingCallees(java.util.Set result)

  Gather the direct contributing callees of this function. A callee is a function that this one calls. A contributing callee is a function whose output is added directly to the output of this function without further processing (other than by attaching it to a parent element or document node). A direct contributing callee is a function that is called directly, rather than indirectly.

  Parameters:
    `result` - the list into which the callees are gathered.

### call

    public ValueRepresentation call(ValueRepresentation[] actualArgs,
                                    XPathContextMajor context)
                             throws XPathException

  Call this function to return a value.

  Parameters:
    `actualArgs` - the arguments supplied to the function. These must have the correct types required by the function signature (it is the caller's responsibility to check this). It is acceptable to supply a `Closure` to represent a value whose evaluation will be delayed until it is needed. The array must be the correct size to match the number of arguments: again, it is the caller's responsibility to check this.
    `context` - This provides the run-time context for evaluating the function. It is the caller's responsibility to allocate a "clean" context for the function to use; the context that is provided will be overwritten by the function.
  Returns:
    a Value representing the result of the function.
  Throws:
    `XPathException`

### process

    public void process(ValueRepresentation[] actualArgs,
                        XPathContextMajor context)
                 throws XPathException

  Call this function in "push" mode, writing the results to the current output destination.

  Parameters:
    `actualArgs` - the arguments supplied to the function. These must have the correct types required by the function signature (it is the caller's responsibility to check this). It is acceptable to supply a `Closure` to represent a value whose evaluation will be delayed until it is needed. The array must be the correct size to match the number of arguments: again, it is the caller's responsibility to check this.
    `context` - This provides the run-time context for evaluating the function. It is the caller's responsibility to allocate a "clean" context for the function to use; the context that is provided will be overwritten by the function.
  Throws:
    `XPathException`

### iterateEvents

    public EventIterator iterateEvents(ValueRepresentation[] actualArgs,
                                       XPathContextMajor context)
                                throws XPathException

  Call this function in "pull" mode, returning the results as a sequence of PullEvents.

  Parameters:
    `actualArgs` - the arguments supplied to the function. These must have the correct types required by the function signature (it is the caller's responsibility to check this). It is acceptable to supply a `Closure` to represent a value whose evaluation will be delayed until it is needed. The array must be the correct size to match the number of arguments: again, it is the caller's responsibility to check this.
    `context` - This provides the run-time context for evaluating the function. It is the caller's responsibility to allocate a "clean" context for the function to use; the context that is provided will be overwritten by the function.
  Returns:
    an iterator over the results of the function call
  Throws:
    `XPathException`

### call

    public ValueRepresentation call(ValueRepresentation[] actualArgs,
                                    Controller controller)
                             throws XPathException

  Call this function. This method allows an XQuery function to be called directly from a Java application. It creates the environment needed to achieve this

  Parameters:
    `actualArgs` - the arguments supplied to the function. These must have the correct types required by the function signature (it is the caller's responsibility to check this). It is acceptable to supply a `Closure` to represent a value whose evaluation will be delayed until it is needed. The array must be the correct size to match the number of arguments: again, it is the caller's responsibility to check this.
    `controller` - This provides the run-time context for evaluating the function. A Controller may be obtained by calling `XQueryExpression.newController()`. This may be used for a series of calls on functions defined in the same module as the XQueryExpression.
  Returns:
    a Value representing the result of the function.
  Throws:
    `XPathException`

### callUpdating

    public void callUpdating(ValueRepresentation[] actualArgs,
                             XPathContextMajor context,
                             PendingUpdateList pul)
                      throws XPathException

  Call an updating function.

  Parameters:
    `actualArgs` - the arguments supplied to the function. These must have the correct types required by the function signature (it is the caller's responsibility to check this). It is acceptable to supply a `Closure` to represent a value whose evaluation will be delayed until it is needed. The array must be the correct size to match the number of arguments: again, it is the caller's responsibility to check this.
    `context` - the dynamic evaluation context
    `pul` - the pending updates list, to which the function's update actions are to be added.
  Throws:
    `XPathException`

### getConstructType

    public int getConstructType()

  Get the type of construct. This will either be the fingerprint of a standard XSLT instruction name (values in `StandardNames`: all less than 1024) or it will be a constant in class `Location`.

  Returns:
    an integer identifying the kind of construct

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