Re: re-entrant parsers, pure_parser, bison, flex

The moderator natters:


      [You have to fiddle the lexer yourself. If you just want to parser to be
      recursive, you need only add the extra &yyval argument to yylex. If you
      want a truly recursive lexer that you can recurse into at any time,
      you're out of luck with flex. -John]


What is `at any time'? If it suffices to be able to use the lexer on a
second file that is included by a first file while the first file is
currently being parsed, lexed, buffered, buffered (again) and read, then
a wrapper around the parser's entry function suffices. This wrapper can
setup a fresh YY_BUFFER_STATE, using yy_create_buffer and
yy_switch_to_buffer (and yy_delete_buffer). If `at any time' is at more
times than this, a similar wrapper can be put around something else,
though I can't imagine the circumstances under which this would be
necessary. --Tiggr
--

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