xref: /external/antlr/antlr-3.4/runtime/ActionScript/project/src/org/antlr/runtime/RecognizerSharedState.as

package org.antlr.runtime {
	
	/** 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.
	 */
	public class RecognizerSharedState {
		/** 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.
		 */
		public var following:Array = new Array();
		public var _fsp:int = -1;
	
		/** 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.
		 */
		public var errorRecovery:Boolean = false;
	
		/** 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.
		 */
		public var lastErrorIndex:int = -1;
	
		/** In lieu of a return value, this indicates that a rule or token
		 *  has failed to match.  Reset to false upon valid token match.
		 */
		public var failed:Boolean = false;

        /** Did the recognizer encounter a syntax error?  Track how many. */
    	public var syntaxErrors:int = 0;
	
		/** If 0, no backtracking is going on.  Safe to exec actions etc...
		 *  If >0 then it's the level of backtracking.
		 */
		public var backtracking:int = 0;
	
		/** An Array[size num rules] of Arrays 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).
		 */
		public var ruleMemo:Array;
	
	
		// LEXER FIELDS (must be in same state object to avoid casting
		//               constantly in generated code and Lexer object) :(
	
	
		/** 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.
		 */
	    public var token:Token;
	
		/** 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.
	 	 */
		public var tokenStartCharIndex:int = -1;
	
		/** The line on which the first character of the token resides */
		public var tokenStartLine:int;
	
		/** The character position of first character within the line */
		public var tokenStartCharPositionInLine:int;
	
		/** The channel number for the current token */
		public var channel:int;
	
		/** The token type for the current token */
		public var type:int;
	
		/** 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.
	 	 */
		public var text:String;
	}

}