net.sf.saxon.instruct
Class UserFunction

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

All Implemented Interfaces:

Serializable, SourceLocator, LocationProvider, Container, InstructionInfoProvider

public final class UserFunction
extends Procedure
implements InstructionInfoProvider

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

Constructor Summary

UserFunction()

UserFunction(Expression body)

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	computeEvaluationMode()
boolean	containsTailCalls()
void	gatherDirectContributingCallees(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	getEvaluationMode() Get the evaluation mode
int	getFunctionNameCode() Get the namepool name code of the function
InstructionInfo	getInstructionInfo() Get the InstructionInfo details about the construct.
int	getNumberOfArguments() Get the arity of this function
UserFunctionParameter[]	getParameterDefinitions()
SequenceType	getResultType(TypeHierarchy th) Get the type of value returned by this function
boolean	isTailRecursive()
void	process(ValueRepresentation[] actualArgs, XPathContextMajor context) Call this function in "push" mode, writing the results to the current output destination.
void	setFunctionNameCode(int nameCode) Set the namepool name code of the function
void	setMemoFunction(boolean isMemo) Mark this function as a memo function (or not)
void	setParameterDefinitions(UserFunctionParameter[] params)
void	setResultType(SequenceType resultType)
void	setTailRecursive(boolean tailCalls, boolean recursiveTailCalls) Indicate whether the function contains a tail call

Methods inherited from class net.sf.saxon.instruct.Procedure

getBody, getColumnNumber, getExecutable, getHostLanguage, getLineNumber, getLineNumber, getLocationProvider, getPublicId, getStackFrameMap, getSystemId, getSystemId, replaceSubExpression, setBody, setExecutable, setHostLanguage, setLineNumber, setStackFrameMap, setSystemId

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

UserFunction

public UserFunction()

UserFunction

public UserFunction(Expression body)

Method Detail

computeEvaluationMode

public void computeEvaluationMode()

setParameterDefinitions

public void setParameterDefinitions(UserFunctionParameter[] params)

getParameterDefinitions

public UserFunctionParameter[] getParameterDefinitions()

setResultType

public void setResultType(SequenceType resultType)

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()

isTailRecursive

public boolean isTailRecursive()

getResultType

public SequenceType getResultType(TypeHierarchy th)

Get the type of value returned by this function

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

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

setFunctionNameCode

public void setFunctionNameCode(int nameCode)

Set the namepool name code of the function

Parameters:

nameCode - represents the function name

getFunctionNameCode

public int getFunctionNameCode()

Get the namepool name code of the function

Returns:

a name code representing the function name

gatherDirectContributingCallees

public void gatherDirectContributingCallees(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

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

getInstructionInfo

public InstructionInfo getInstructionInfo()

Get the InstructionInfo details about the construct. This information isn't used for tracing, but it is available when inspecting the context stack.

Specified by:

getInstructionInfo in interface InstructionInfoProvider