\def\optimization{5}

\input yycommon.sty % general routines for stack and array access
\input yymisc.sty   % helper macros (stack manipulation, table processing, value stack pointers)
\input yyinput.sty  % input functions
\input yyparse.sty  % parser machinery
\input flex.sty     % lexer functions
\input yyfaststack.sty % sped up stack access functions
\input yyboth.sty   % parser initializatio, optimization

\def\mainnamespace{[expression]} % the expression parser namespace 
\let\parsernamespace\mainnamespace

\input ptab.tex % load parser tables
\settokens
\input ltab.tex % load lexer tables
\let\yylexreturn\yylexreturnregular

\newparserstate % initialize the new parser
\newlexerstate  % initialize the new lexer

\optimizeall % put optimization options into effect
