Lexer Properties

What is the index of the current character of lookahead?

Return whether or not a backtracking attempt failed.

For debugging and other purposes, might want the grammar name. Have ANTLR generate an implementation for this method.

Get number of recognition errors (lexer, parser, tree parser). Each recognizer tracks its own number. So parser and lexer each have separate count. Does not count the spurious errors found between an error and next valid token match

Gets or sets the text matched so far for the current token or any text override.

Used to print out token names like ID during debugging and error reporting. The generated parsers implement a method that overrides this to point to their String[] tokenNames.