Class ParseTreeBuilder

java.lang.Object
org.antlr.runtime.debug.BlankDebugEventListener
org.antlr.runtime.debug.ParseTreeBuilder
All Implemented Interfaces:
DebugEventListener
public class ParseTreeBuilder extends BlankDebugEventListener
This parser listener tracks rule entry/exit and token matches to build a simple parse tree using ParseTree nodes.

  • Field Details

  • Constructor Details

    • ParseTreeBuilder

      public ParseTreeBuilder(String grammarName)

  • Method Details

    • getTree

      public ParseTree getTree()

    • create

      public ParseTree create(Object payload)
      What kind of node to create. You might want to override so I factored out creation here.

    • epsilonNode

      public ParseTree epsilonNode()

    • enterDecision

      public void enterDecision(int d, boolean couldBacktrack)
      Backtracking or cyclic DFA, don't want to add nodes to tree
      Specified by:
      enterDecision in interface DebugEventListener
      Overrides:
      enterDecision in class BlankDebugEventListener

    • exitDecision

      public void exitDecision(int i)
      Specified by:
      exitDecision in interface DebugEventListener
      Overrides:
      exitDecision in class BlankDebugEventListener

    • enterRule

      public void enterRule(String filename, String ruleName)
      Description copied from interface: DebugEventListener
      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.
      Specified by:
      enterRule in interface DebugEventListener
      Overrides:
      enterRule in class BlankDebugEventListener

    • exitRule

      public void exitRule(String filename, String ruleName)
      Description copied from interface: DebugEventListener
      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.
      Specified by:
      exitRule in interface DebugEventListener
      Overrides:
      exitRule in class BlankDebugEventListener

    • consumeToken

      public void consumeToken(Token token)
      Description copied from interface: DebugEventListener
      An input token was consumed; matched by any kind of element. Trigger after the token was matched by things like match(), matchAny().
      Specified by:
      consumeToken in interface DebugEventListener
      Overrides:
      consumeToken in class BlankDebugEventListener

    • consumeHiddenToken

      public void consumeHiddenToken(Token token)
      Description copied from interface: DebugEventListener
      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).
      Specified by:
      consumeHiddenToken in interface DebugEventListener
      Overrides:
      consumeHiddenToken in class BlankDebugEventListener

    • recognitionException

      public void recognitionException(RecognitionException e)
      Description copied from interface: DebugEventListener
      A recognition exception occurred such as NoViableAltException. 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 RecognitionException data fields are transmitted. The token object or whatever that caused the problem was the last object referenced by LT. The immediately preceding LT 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 LT(1) enterRule b location 7 1 enter decision 3 LT(1) exit decision 3 enterAlt1 location 7 5 LT(1) consumeToken [c/<4>,1:0] location 7 7 enterSubRule 2 enter decision 2 LT(1) LT(1) recognitionException NoViableAltException 2 1 2 exit decision 2 exitSubRule 2 beginResync LT(1) consumeToken [c/<4>,1:1] LT(1) endResync LT(-1) exitRule b terminate
      Specified by:
      recognitionException in interface DebugEventListener
      Overrides:
      recognitionException in class BlankDebugEventListener