org.antlr.runtime

Class RecognizerSharedState

java.lang.Object

org.antlr.runtime.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 Summary

Fields

Modifier and Type	Field and Description
int	_fsp
int	backtracking If 0, no backtracking is going on.
int	channel The channel number for the current token
boolean	errorRecovery This is true when we see an error and before having successfully matched a token.
boolean	failed In lieu of a return value, this indicates that a rule or token has failed to match.
BitSet[]	following Track the set of token types that can follow any rule invocation.
int	lastErrorIndex The index into the input stream where the last error occurred.
Map[]	ruleMemo An array[size num rules] of Map that tracks the stop token index for each rule.
int	syntaxErrors Did the recognizer encounter a syntax error? Track how many.
String	text You can set the text for the current token to override what is in the input char buffer.
Token	token The goal of all lexer rules/methods is to create a token object.
int	tokenStartCharIndex What character index in the stream did the current token start at? Needed, for example, to get the text for current token.
int	tokenStartCharPositionInLine The character position of first character within the line
int	tokenStartLine The line on which the first character of the token resides
int	type The token type for the current token

Constructor Summary

Constructors

Constructor and Description
RecognizerSharedState()
RecognizerSharedState(RecognizerSharedState state)

Method Summary

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

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[] ruleMemo

An array[size num rules] of Map 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()

RecognizerSharedState

public RecognizerSharedState(RecognizerSharedState state)