Module: ANTLR3::Debug::EventListener

Included in:
EventHub, EventSocketProxy, RuleTracer, TraceEventListener, Profile::Profiler
Defined in:
lib/antlr3/debug.rb

Overview

A listener that simply records text representations of the events. Useful for debugging the debugging facility ;) Subclasses can override the record() method (which defaults to printing to stdout) to record the events in a different way.

Constant Summary collapse

PROTOCOL_VERSION = 
'2'
EVENTS = 
[ 
  :add_child, :backtrack, :become_root, :begin_backtrack,
  :begin_resync, :commence, :consume_hidden_token,
  :consume_node, :consume_token, :create_node, :end_backtrack,
  :end_resync, :enter_alternative, :enter_decision, :enter_rule,
  :enter_sub_rule, :error_node, :exit_decision, :exit_rule,
  :exit_sub_rule, :flat_node, :location, :look, :mark,
  :recognition_exception, :resync, :rewind,
  :semantic_predicate, :set_token_boundaries, :terminate
].freeze

Instance Method Summary collapse

Instance Method Details

#add_child(root, child) ⇒ Object

Make childID a child of rootID. If you are receiving this event over a socket via RemoteDebugEventSocketListener then only IDs are set.

See Also:

  • ANTLR3::Debug::EventListener.antlr3antlr3.treeantlr3.tree.TreeAdaptorantlr3.tree.TreeAdaptor.addChild()


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# File 'lib/antlr3/debug.rb', line 663

def add_child( root, child )
  # do nothing
end

#backtrack(level) ⇒ Object 



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# File 'lib/antlr3/debug.rb', line 479

def backtrack( level )
  begin_backtrack( level )
  successful = yield( self )
  end_backtrack( level, successful )
end

#become_root(new_root, old_root) ⇒ Object

Make a node the new root of an existing root. Note: the newRootID parameter is possibly different than the TreeAdaptor.becomeRoot() newRoot parameter. In our case, it will always be the result of calling TreeAdaptor.becomeRoot() and not root_n or whatever. The listener should assume that this event occurs only when the current subrule (or rule) subtree is being reset to newRootID. If you are receiving this event over a socket via RemoteDebugEventSocketListener then only IDs are set.

See Also:

  • ANTLR3::Debug::EventListener.antlr3antlr3.treeantlr3.tree.TreeAdaptorantlr3.tree.TreeAdaptor.becomeRoot()


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# File 'lib/antlr3/debug.rb', line 654

def become_root( new_root, old_root )
  # do nothing
end

#begin_backtrack(level) ⇒ Object 



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# File 'lib/antlr3/debug.rb', line 471

def begin_backtrack( level )
  # do nothing
end

#begin_resync ⇒ Object

Indicates the recognizer is about to consume tokens to resynchronize the parser. Any consume events from here until the recovered event are not part of the parse–they are dead tokens.



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# File 'lib/antlr3/debug.rb', line 554

def begin_resync()
  # do nothing
end

#commence ⇒ Object

Announce that parsing has begun. Not technically useful except for sending events over a socket. A GUI for example will launch a thread to connect and communicate with a remote parser. The thread will want to notify the GUI when a connection is made. ANTLR parsers trigger this upon entry to the first rule (the ruleLevel is used to figure this out).



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# File 'lib/antlr3/debug.rb', line 589

def commence(  )
  # do nothing
end

#consume_hidden_token(tree) ⇒ Object

An off-channel input token was consumed. Trigger after the token was matched by things like match(), matchAny(). (unless of course the hidden token is first stuff in the input stream).



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# File 'lib/antlr3/debug.rb', line 441

def consume_hidden_token( tree )
  # do nothing
end

#consume_node(tree) ⇒ Object

Input for a tree parser is an AST, but we know nothing for sure about a node except its type and text (obtained from the adaptor). This is the analog of the consumeToken method. Again, the ID is the hashCode usually of the node so it only works if hashCode is not implemented. If the type is UP or DOWN, then the ID is not really meaningful as it’s fixed–there is just one UP node and one DOWN navigation node.



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# File 'lib/antlr3/debug.rb', line 610

def consume_node( tree )
  # do nothing
end

#consume_token(tree) ⇒ Object

An input token was consumed; matched by any kind of element. Trigger after the token was matched by things like match(), matchAny().



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# File 'lib/antlr3/debug.rb', line 433

def consume_token( tree )
  # do nothing
end

#create_node(node, token = nil) ⇒ Object

Announce a new node built from token elements such as type etc… If you are receiving this event over a socket via RemoteDebugEventSocketListener then only tree.ID, type, text are set.



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# File 'lib/antlr3/debug.rb', line 638

def create_node( node, token = nil )
  # do nothing
end

#end_backtrack(level, successful) ⇒ Object 



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# File 'lib/antlr3/debug.rb', line 475

def end_backtrack( level, successful )
  # do nothing
end

#end_resync ⇒ Object

Indicates that the recognizer has finished consuming tokens in order to resychronize. There may be multiple beginResync/endResync pairs before the recognizer comes out of errorRecovery mode (in which multiple errors are suppressed). This will be useful in a gui where you want to probably grey out tokens that are consumed but not matched to anything in grammar. Anything between a beginResync/endResync pair was tossed out by the parser.



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# File 'lib/antlr3/debug.rb', line 566

def end_resync()
  # do nothing
end

#enter_alternative(alt) ⇒ Object

Because rules can have lots of alternatives, it is very useful to know which alt you are entering. This is 1..n for n alts.



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# File 'lib/antlr3/debug.rb', line 391

def enter_alternative( alt )
  # do nothing
end

#enter_decision(decision_number) ⇒ Object

Every decision, fixed k or arbitrary, has an enter/exit event so that a GUI can easily track what look/consume events are associated with prediction. You will see a single enter/exit subrule but multiple enter/exit decision events, one for each loop iteration.



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# File 'lib/antlr3/debug.rb', line 422

def enter_decision( decision_number )
  # do nothing
end

#enter_rule(grammar_file, rule_name) ⇒ Object

The parser has just entered a rule. No decision has been made about which alt is predicted. This is fired AFTER init actions have been executed. Attributes are defined and available etc… The grammarFileName allows composite grammars to jump around among multiple grammar files.



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# File 'lib/antlr3/debug.rb', line 384

def enter_rule( grammar_file, rule_name )
  # do nothing
end

#enter_subrule(decision_number) ⇒ Object

Track entry into any (…) subrule other EBNF construct



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# File 'lib/antlr3/debug.rb', line 408

def enter_subrule( decision_number )
  # do nothing
end

#error_node(tree) ⇒ Object

Upon syntax error, recognizers bracket the error with an error node if they are building ASTs.



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# File 'lib/antlr3/debug.rb', line 629

def error_node( tree )
  # do nothing
end

#examine_rule_memoization(rule) ⇒ Object 



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# File 'lib/antlr3/debug.rb', line 675

def examine_rule_memoization( rule )
  # do nothing
end

#exit_decision(decision_number) ⇒ Object 



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# File 'lib/antlr3/debug.rb', line 426

def exit_decision( decision_number )
  # do nothing
end

#exit_rule(grammar_file, rule_name) ⇒ Object

This is the last thing executed before leaving a rule. It is executed even if an exception is thrown. This is triggered after error reporting and recovery have occurred (unless the exception is not caught in this rule). This implies an “exitAlt” event. The grammarFileName allows composite grammars to jump around among multiple grammar files.



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# File 'lib/antlr3/debug.rb', line 402

def exit_rule( grammar_file, rule_name )
  # do nothing
end

#exit_subrule(decision_number) ⇒ Object 



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# File 'lib/antlr3/debug.rb', line 412

def exit_subrule( decision_number )
  # do nothing
end

#flat_node(tree) ⇒ Object

A nil was created (even nil nodes have a unique ID… they are not “null” per se). As of 4/28/2006, this seems to be uniquely triggered when starting a new subtree such as when entering a subrule in automatic mode and when building a tree in rewrite mode. If you are receiving this event over a socket via RemoteDebugEventSocketListener then only tree.ID is set.



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# File 'lib/antlr3/debug.rb', line 622

def flat_node( tree )
  # do nothing
end

#location(line, position) ⇒ Object

To watch a parser move through the grammar, the parser needs to inform the debugger what line/charPos it is passing in the grammar. For now, this does not know how to switch from one grammar to the other and back for island grammars etc… This should also allow breakpoints because the debugger can stop the parser whenever it hits this line/pos.



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# File 'lib/antlr3/debug.rb', line 492

def location( line, position )
  # do nothing
end

#look(i, tree) ⇒ Object

Somebody (anybody) looked ahead. Note that this actually gets triggered by both peek and look calls. The debugger will want to know which Token object was examined. Like consumeToken, this indicates what token was seen at that depth. A remote debugger cannot look ahead into a file it doesn’t have so look events must pass the token even if the info is redundant.



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# File 'lib/antlr3/debug.rb', line 452

def look( i, tree )
  # do nothing
end

#mark(marker) ⇒ Object

The parser is going to look arbitrarily ahead; mark this location, the token stream’s marker is sent in case you need it.



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# File 'lib/antlr3/debug.rb', line 459

def mark( marker )
  # do nothing
end

#on(event_name, &block) ⇒ Object 



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# File 'lib/antlr3/debug.rb', line 679

def on( event_name, &block )
  sclass = class << self; self; end
  sclass.send( :define_method, event_name, &block )
end

#recognition_exception(exception) ⇒ Object

A recognition exception occurred such as NoViableAltError. I made this a generic event so that I can alter the exception hierachy later without having to alter all the debug objects. Upon error, the stack of enter rule/subrule must be properly unwound. If no viable alt occurs it is within an enter/exit decision, which also must be rewound. Even the rewind for each mark must be unwount. In the Java target this is pretty easy using try/finally, if a bit ugly in the generated code. The rewind is generated in DFA.predict() actually so no code needs to be generated for that. For languages w/o this “finally” feature (C++?), the target implementor will have to build an event stack or something. Across a socket for remote debugging, only the RecognitionError data fields are transmitted. The token object or whatever that caused the problem was the last object referenced by look. The immediately preceding look event should hold the unexpected Token or char. Here is a sample event trace for grammar: b : C (;A|B) // ; is there to prevent A|B becoming a set | D ; The sequence for this rule (with no viable alt in the subrule) for input ‘c c’ (there are 3 tokens) is: commence look enterRule b location 7 1 enter decision 3 look exit decision 3 enterAlt1 location 7 5 look consumeToken [c/<4>,1:0] location 7 7 enterSubRule 2 enter decision 2 look look recognitionError NoViableAltError 2 1 2 exit decision 2 exitSubRule 2 beginResync look consumeToken [c/<4>,1:1] look endResync look(-1) exitRule b terminate



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# File 'lib/antlr3/debug.rb', line 546

def recognition_exception( exception )
  # do nothing
end

#resync {|_self| ... } ⇒ Object

Yields:

  • (_self)

Yield Parameters:



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# File 'lib/antlr3/debug.rb', line 570

def resync
  begin_resync
  yield( self )
  end_resync
end

#rewind(marker = nil) ⇒ Object

After an arbitrairly long look as with a cyclic DFA (or with any backtrack), this informs the debugger that stream should be rewound to the position associated with marker.



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# File 'lib/antlr3/debug.rb', line 467

def rewind( marker = nil )
  # do nothing
end

#semantic_predicate(result, predicate) ⇒ Object

A semantic predicate was evaluate with this result and action text



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# File 'lib/antlr3/debug.rb', line 578

def semantic_predicate( result, predicate )
  # do nothing
end

#set_token_boundaries(tree, token_start_index, token_stop_index) ⇒ Object

Set the token start/stop token index for a subtree root or node. If you are receiving this event over a socket via RemoteDebugEventSocketListener then only tree.ID is set.



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# File 'lib/antlr3/debug.rb', line 671

def set_token_boundaries( tree, token_start_index, token_stop_index )
  # do nothing
end

#terminate ⇒ Object

Parsing is over; successfully or not. Mostly useful for telling remote debugging listeners that it’s time to quit. When the rule invocation level goes to zero at the end of a rule, we are done parsing.



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# File 'lib/antlr3/debug.rb', line 598

def terminate(  )
  # do nothing
end