module ANTLR3::Debug::EventListener
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.
Constants
- EVENTS
- PROTOCOL_VERSION
Public Instance Methods
Make childID a child of rootID. If you are receiving this event over a socket via RemoteDebugEventSocketListener then only IDs are set. @see antlr3.tree.TreeAdaptor.addChild()
# File lib/antlr3/debug.rb, line 663 def add_child( root, child ) # do nothing end
# File lib/antlr3/debug.rb, line 479 def backtrack( level ) begin_backtrack( level ) successful = yield( self ) end_backtrack( level, successful ) end
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 antlr3.tree.TreeAdaptor.becomeRoot()
# File lib/antlr3/debug.rb, line 654 def become_root( new_root, old_root ) # do nothing end
# File lib/antlr3/debug.rb, line 471 def begin_backtrack( level ) # do nothing end
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.
# File lib/antlr3/debug.rb, line 554 def begin_resync() # do nothing end
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).
# File lib/antlr3/debug.rb, line 589 def commence( ) # do nothing end
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.
# File lib/antlr3/debug.rb, line 610 def consume_node( tree ) # do nothing end
An input token was consumed; matched by any kind of element. Trigger after the token was matched by things like match(), matchAny().
# File lib/antlr3/debug.rb, line 433 def consume_token( tree ) # do nothing end
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.
# File lib/antlr3/debug.rb, line 638 def create_node( node, token = nil ) # do nothing end
# File lib/antlr3/debug.rb, line 475 def end_backtrack( level, successful ) # do nothing end
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.
# File lib/antlr3/debug.rb, line 566 def end_resync() # do nothing end
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.
# File lib/antlr3/debug.rb, line 391 def enter_alternative( alt ) # do nothing end
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.
# File lib/antlr3/debug.rb, line 422 def enter_decision( decision_number ) # do nothing end
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.
# File lib/antlr3/debug.rb, line 384 def enter_rule( grammar_file, rule_name ) # do nothing end
Track entry into any (…) subrule other EBNF construct
# File lib/antlr3/debug.rb, line 408 def enter_subrule( decision_number ) # do nothing end
Upon syntax error, recognizers bracket the error with an error node if they are building ASTs.
# File lib/antlr3/debug.rb, line 629 def error_node( tree ) # do nothing end
# File lib/antlr3/debug.rb, line 675 def examine_rule_memoization( rule ) # do nothing end
# File lib/antlr3/debug.rb, line 426 def exit_decision( decision_number ) # do nothing end
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.
# File lib/antlr3/debug.rb, line 402 def exit_rule( grammar_file, rule_name ) # do nothing end
# File lib/antlr3/debug.rb, line 412 def exit_subrule( decision_number ) # do nothing end
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.
# File lib/antlr3/debug.rb, line 622 def flat_node( tree ) # do nothing end
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.
# File lib/antlr3/debug.rb, line 492 def location( line, position ) # do nothing end
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.
# File lib/antlr3/debug.rb, line 452 def look( i, tree ) # do nothing end
The parser is going to look arbitrarily ahead; mark this location, the token stream’s marker is sent in case you need it.
# File lib/antlr3/debug.rb, line 459 def mark( marker ) # do nothing end
# 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
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
# File lib/antlr3/debug.rb, line 546 def recognition_exception( exception ) # do nothing end
# File lib/antlr3/debug.rb, line 570 def resync begin_resync yield( self ) end_resync end
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.
# File lib/antlr3/debug.rb, line 467 def rewind( marker = nil ) # do nothing end
A semantic predicate was evaluate with this result and action text
# File lib/antlr3/debug.rb, line 578 def semantic_predicate( result, predicate ) # do nothing end
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.
# File lib/antlr3/debug.rb, line 671 def set_token_boundaries( tree, token_start_index, token_stop_index ) # do nothing end
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.
# File lib/antlr3/debug.rb, line 598 def terminate( ) # do nothing end