All Known Implementing Classes:

AbstractTraceListener, ContentHandlerProxy.ContentHandlerProxyTraceListener, TimingTraceListener, TraceEventMulticaster, XQueryTraceListener, XSLTTraceListener
```
public interface TraceListener
```
This interface defines methods that are called by Saxon during the execution of a stylesheet or query, if tracing is switched on. Tracing can be switched on by nominating an implementation of this class using the TRACE_LISTENER feature of the TransformerFactory, or using the addTraceListener() method of the Controller.

Method Summary

All Methods Instance Methods Default Methods
Modifier and Type	Method	Description
`default void`	`close()`	Method called at the end of execution, that is, when the run-time execution ends.
`default void`	`endCurrentItem(Item currentItem)`	Method that is called when an instruction has finished processing a new current item and is ready to select a new current item or revert to the previous current item.
`default void`	`endRuleSearch(java.lang.Object rule, Mode mode, Item item)`	Method called when a rule search has completed.
`default void`	`enter(Traceable instruction, java.util.Map<java.lang.String,java.lang.Object> properties, XPathContext context)`	Method that is called when an instruction in the stylesheet gets processed.
`default void`	`leave(Traceable instruction)`	Method that is called after processing an instruction of the stylesheet, that is, after any child instructions have been processed.
`default void`	`open(Controller controller)`	Method called at the start of execution, that is, when the run-time transformation starts.
`default void`	`setOutputDestination(Logger stream)`	Method called to supply the destination for output.
`default void`	`startCurrentItem(Item currentItem)`	Method that is called by an instruction that changes the current item in the source document: that is, xsl:for-each, xsl:apply-templates, xsl:for-each-group.
`default void`	`startRuleSearch()`	Method called when a search for a template rule is about to start

- Method Detail
  - setOutputDestination
```
default void setOutputDestination(Logger stream)
```
    Method called to supply the destination for output. The default implementation does nothing.
    
    Parameters:
    
    stream - a Logger to which any output produced by the TraceListener should be written
    
    Since:
    
    8.0. Changed in 9.6 to accept a Logger.
  - open
```
default void open(Controller controller)
```
    Method called at the start of execution, that is, when the run-time transformation starts. The default implementation does nothing.
    
    Parameters:
    
    controller - identifies the transformation controller, and provides the listener with access to context and configuration information
  - close
```
default void close()
```
    Method called at the end of execution, that is, when the run-time execution ends. The default implementation does nothing.
  - enter
```
default void enter(Traceable instruction,
                   java.util.Map<java.lang.String,java.lang.Object> properties,
                   XPathContext context)
```
    Method that is called when an instruction in the stylesheet gets processed. Default implementation does nothing.
    
    Parameters:
    
    instruction - 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.
    
    properties - extra information about the instruction to be included in the trace
    
    context - the XPath evaluation context
  - leave
```
default void leave(Traceable instruction)
```
    Method that is called after processing an instruction of the stylesheet, that is, after any child instructions have been processed. Default implementation does nothing.
    
    Parameters:
    
    instruction - 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
```
default void startCurrentItem(Item currentItem)
```
    Method that is called by an instruction that changes the current item in the source document: that is, xsl:for-each, xsl:apply-templates, xsl:for-each-group. The method is called after the enter method for the relevant instruction, and is called once for each item processed. The default implementation does nothing.
    
    Parameters:
    
    currentItem - the new current item. Item objects are not mutable; it is safe to retain a reference to the Item for later use.
  - endCurrentItem
```
default void endCurrentItem(Item currentItem)
```
    Method that is called when an instruction has finished processing a new current item and is ready to select a new current item or revert to the previous current item. The method will be called before the leave() method for the instruction that made this item current. The default implementation does nothing.
    
    Parameters:
    
    currentItem - 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.
  - startRuleSearch
```
default void startRuleSearch()
```
    Method called when a search for a template rule is about to start
  - endRuleSearch
```
default void endRuleSearch(java.lang.Object rule,
                           Mode mode,
                           Item item)
```
    Method called when a rule search has completed.
    
    Parameters:
    
    rule - the rule (or possible built-in ruleset) that has been selected
    
    mode - the mode in operation
    
    item - the item that was checked against

Interface TraceListener

Method Summary

Method Detail

setOutputDestination

open

close

enter

leave

startCurrentItem

endCurrentItem

startRuleSearch

endRuleSearch