Package org.antlr.runtime

Class RecognizerSharedState

  • public class RecognizerSharedState
extends Object
    The set of fields needed by an abstract recognizer to recognize input and recover from errors etc... As a separate state object, it can be shared among multiple grammars; e.g., when one grammar imports another. These fields are publically visible but the actual state pointer per parser is protected.

    • Field Detail

      • following

        public BitSet[] following
        Track the set of token types that can follow any rule invocation. Stack grows upwards. When it hits the max, it grows 2x in size and keeps going.

      • _fsp

        public int _fsp

      • errorRecovery

        public boolean errorRecovery
        This is true when we see an error and before having successfully matched a token. Prevents generation of more than one error message per error.

      • lastErrorIndex

        public int lastErrorIndex
        The index into the input stream where the last error occurred. This is used to prevent infinite loops where an error is found but no token is consumed during recovery...another error is found, ad naseum. This is a failsafe mechanism to guarantee that at least one token/tree node is consumed for two errors.

      • failed

        public boolean failed
        In lieu of a return value, this indicates that a rule or token has failed to match. Reset to false upon valid token match.

      • syntaxErrors

        public int syntaxErrors
        Did the recognizer encounter a syntax error? Track how many.

      • backtracking

        public int backtracking
        If 0, no backtracking is going on. Safe to exec actions etc... If >0 then it's the level of backtracking.

      • ruleMemo

        public Map<Integer,​Integer>[] ruleMemo
        An array[size num rules] of Map<Integer,Integer> that tracks the stop token index for each rule. ruleMemo[ruleIndex] is the memoization table for ruleIndex. For key ruleStartIndex, you get back the stop token for associated rule or MEMO_RULE_FAILED. This is only used if rule memoization is on (which it is by default).

      • token

        public Token token
        The goal of all lexer rules/methods is to create a token object. This is an instance variable as multiple rules may collaborate to create a single token. nextToken will return this object after matching lexer rule(s). If you subclass to allow multiple token emissions, then set this to the last token to be matched or something nonnull so that the auto token emit mechanism will not emit another token.

      • tokenStartCharIndex

        public int tokenStartCharIndex
        What character index in the stream did the current token start at? Needed, for example, to get the text for current token. Set at the start of nextToken.

      • tokenStartLine

        public int tokenStartLine
        The line on which the first character of the token resides

      • tokenStartCharPositionInLine

        public int tokenStartCharPositionInLine
        The character position of first character within the line

      • channel

        public int channel
        The channel number for the current token

      • type

        public int type
        The token type for the current token

      • text

        public String text
        You can set the text for the current token to override what is in the input char buffer. Use setText() or can set this instance var.

    • Constructor Detail

      • RecognizerSharedState

        public RecognizerSharedState()