net.sf.saxon.trace
Class TraceEventMulticaster

java.lang.Object
  net.sf.saxon.trace.TraceEventMulticaster

All Implemented Interfaces:

EventListener, TraceListener

public class TraceEventMulticaster
extends Object
implements TraceListener

A class which implements efficient and thread-safe multi-cast event dispatching for the TraceListener evants.

Grabbed from java.awt.AWTEventMulticaster

Field Summary

protected EventListener	a
protected EventListener	b

Constructor Summary

protected

TraceEventMulticaster(EventListener a, EventListener b) Creates an event multicaster instance which chains listener-a with listener-b.

Method Summary

static TraceListener	add(TraceListener a, TraceListener b) Adds trace-listener-a with trace-listener-b and returns the resulting multicast listener.
protected static EventListener	addInternal(EventListener a, EventListener b) Returns the resulting multicast listener from adding listener-a and listener-b together.
void	close() Called at end
void	endCurrentItem(Item item) Called when an item ceases to be the current item
void	enter(InstructionInfo element, XPathContext context) Called when an element of the stylesheet gets processed
void	leave(InstructionInfo element) Called after an element of the stylesheet got processed
void	open() Called at start
protected EventListener	remove(EventListener oldl) Removes a listener from this multicaster and returns the resulting multicast listener.
static TraceListener	remove(TraceListener l, TraceListener oldl) Removes the old trace-listener from trace-listener-l and returns the resulting multicast listener.
protected static EventListener	removeInternal(EventListener l, EventListener oldl) Returns the resulting multicast listener after removing the old listener from listener-l.
void	startCurrentItem(Item item) Called when an item becomes current

Methods inherited from class java.lang.Object

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

Field Detail

a

protected final EventListener a

b

protected final EventListener b

Constructor Detail

TraceEventMulticaster

protected TraceEventMulticaster(EventListener a,
                                EventListener b)

Creates an event multicaster instance which chains listener-a with listener-b.

Parameters:

a - listener-a

b - listener-b

Method Detail

remove

protected EventListener remove(EventListener oldl)

Removes a listener from this multicaster and returns the resulting multicast listener.

Parameters:

oldl - the listener to be removed

open

public void open()

Called at start

Specified by:

open in interface TraceListener

close

public void close()

Called at end

Specified by:

close in interface TraceListener

enter

public void enter(InstructionInfo element,
                  XPathContext context)

Called when an element of the stylesheet gets processed

Specified by:

enter in interface TraceListener

Parameters:

element - gives information about the instruction being executed, and about the context in which it is executed. This object is mutable, so if information from the InstructionInfo is to be retained, it must be copied.

leave

public void leave(InstructionInfo element)

Called after an element of the stylesheet got processed

Specified by:

leave in interface TraceListener

Parameters:

element - gives the same information that was supplied to the enter method, though it is not necessarily the same object. Note that the line number of the instruction is that of the start tag in the source stylesheet, not the line number of the end tag.

startCurrentItem

public void startCurrentItem(Item item)

Called when an item becomes current

Specified by:

startCurrentItem in interface TraceListener

Parameters:

item - the new current item. Item objects are not mutable; it is safe to retain a reference to the Item for later use.

endCurrentItem

public void endCurrentItem(Item item)

Called when an item ceases to be the current item

Specified by:

endCurrentItem in interface TraceListener

Parameters:

item - the item that was current, whose processing is now complete. This will represent the same underlying item as the corresponding startCurrentItem() call, though it will not necessarily be the same actual object.

add

public static TraceListener add(TraceListener a,
                                TraceListener b)

Adds trace-listener-a with trace-listener-b and returns the resulting multicast listener.

Parameters:

a - trace-listener-a

b - trace-listener-b

remove

public static TraceListener remove(TraceListener l,
                                   TraceListener oldl)

Removes the old trace-listener from trace-listener-l and returns the resulting multicast listener.

Parameters:

l - trace-listener-l

oldl - the trace-listener being removed

addInternal

protected static EventListener addInternal(EventListener a,
                                           EventListener b)

Returns the resulting multicast listener from adding listener-a and listener-b together. If listener-a is null, it returns listener-b; If listener-b is null, it returns listener-a If neither are null, then it creates and returns a new EventMulticaster instance which chains a with b.

Parameters:

a - event listener-a

b - event listener-b

removeInternal

protected static EventListener removeInternal(EventListener l,
                                              EventListener oldl)

Returns the resulting multicast listener after removing the old listener from listener-l. If listener-l equals the old listener OR listener-l is null, returns null. Else if listener-l is an instance of SaxonEventMulticaster, then it removes the old listener from it. Else, returns listener l.

Parameters:

l - the listener being removed from

oldl - the listener being removed