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()
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	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(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.
StructuredQName	getFunctionName() Get the function name
InstructionInfo	getInstructionInfo() Get the InstructionInfo details about the construct.
int	getNumberOfArguments() Get the arity of this function
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
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

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()

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

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

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(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

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