Class ATN

java.lang.Object
org.graalvm.shadowed.org.antlr.v4.runtime.atn.ATN
public class ATN extends Object

  • Field Details

    • INVALID_ALT_NUMBER

      public static final int INVALID_ALT_NUMBER
      See Also:

    • states

      public final List<ATNState> states

    • decisionToState

      public final List<DecisionState> decisionToState
      Each subrule/rule is a decision point and we must track them so we can go back later and build DFA predictors for them. This includes all the rules, subrules, optional blocks, ()+, ()* etc...

    • ruleToStartState

      public RuleStartState[] ruleToStartState
      Maps from rule index to starting state number.

    • ruleToStopState

      public RuleStopState[] ruleToStopState
      Maps from rule index to stop state number.

    • modeNameToStartState

      public final Map<String,TokensStartState> modeNameToStartState

    • grammarType

      public final ATNType grammarType
      The type of the ATN.

    • maxTokenType

      public final int maxTokenType
      The maximum value for any symbol recognized by a transition in the ATN.

    • ruleToTokenType

      public int[] ruleToTokenType
      For lexer ATNs, this maps the rule index to the resulting token type. For parser ATNs, this maps the rule index to the generated bypass token type if the ATNDeserializationOptions.isGenerateRuleBypassTransitions() deserialization option was specified; otherwise, this is null.

    • lexerActions

      public LexerAction[] lexerActions
      For lexer ATNs, this is an array of LexerAction objects which may be referenced by action transitions in the ATN.

    • modeToStartState

      public final List<TokensStartState> modeToStartState

  • Constructor Details

    • ATN

      public ATN(ATNType grammarType, int maxTokenType)
      Used for runtime deserialization of ATNs from strings

  • Method Details

    • nextTokens

      public IntervalSet nextTokens(ATNState s, RuleContext ctx)
      Compute the set of valid tokens that can occur starting in state s. If ctx is null, the set of tokens will not include what can follow the rule surrounding s. In other words, the set will be restricted to tokens reachable staying within s's rule.

    • nextTokens

      public IntervalSet nextTokens(ATNState s)
      Compute the set of valid tokens that can occur starting in s and staying in same rule. Token.EPSILON is in set if we reach end of rule.

    • addState

      public void addState(ATNState state)

    • removeState

      public void removeState(ATNState state)

    • defineDecisionState

      public int defineDecisionState(DecisionState s)

    • getDecisionState

      public DecisionState getDecisionState(int decision)

    • getNumberOfDecisions

      public int getNumberOfDecisions()

    • getExpectedTokens

      public IntervalSet getExpectedTokens(int stateNumber, RuleContext context)
      Computes the set of input symbols which could follow ATN state number stateNumber in the specified full context. This method considers the complete parser context, but does not evaluate semantic predicates (i.e. all predicates encountered during the calculation are assumed true). If a path in the ATN exists from the starting state to the RuleStopState of the outermost context without matching any symbols, Token.EOF is added to the returned set.

      If context is null, it is treated as ParserRuleContext.EMPTY.

      Note that this does NOT give you the set of all tokens that could appear at a given token position in the input phrase. In other words, it does not answer: "Given a specific partial input phrase, return the set of all tokens that can follow the last token in the input phrase." The big difference is that with just the input, the parser could land right in the middle of a lookahead decision. Getting all *possible* tokens given a partial input stream is a separate computation. See https://github.com/antlr/antlr4/issues/1428 For this function, we are specifying an ATN state and call stack to compute what token(s) can come next and specifically: outside of a lookahead decision. That is what you want for error reporting and recovery upon parse error.
      Parameters:
      stateNumber - the ATN state number
      context - the full parse context
      Returns:
      The set of potentially valid input symbols which could follow the specified state in the specified context.
      Throws:
      IllegalArgumentException - if the ATN does not contain a state with number stateNumber