bnf.sty

%This _sty_ file was developed by Hugh Osborne at the University of
%Nijmegen, The Netherlands. It may be freely distributed under
%condition that this notice is always included in any copy distributed.
%No charge may be made for (copies of) this file, nor may any other
%remuneration be requested.

\typeout{Style-Option: `bnf' v1.1a <92/01/30> (Hugh Osborne/br)}

\def\@actifygrammarchars{%
	\catcode`\"\active%
	\catcode`\:\active%
	\catcode`\,\active%
	\catcode`\;\active%
	\catcode`\.\active%
	\catcode`\<\active%
	\catcode`\>\active}

\def\@deactifygrammarchars{%
	\@makeother\"%
	\@makeother\:%
	\@makeother\,%
	\@makeother\;%
	\@makeother\.%
	\@makeother\<%
	\@makeother\>}

\let\escapegrammar=\@deactifygrammarchars

\begingroup
  \@deactifygrammarchars
  \global\let\quotesymbol="
  \global\let\lessthan=<
  \global\let\greaterthan=>
\endgroup

\newif\if@outsidestring \@outsidestringtrue

\def\@first#1#2{#1}
\def\@second#1#2{#2}

\begingroup

\@actifygrammarchars

   \gdef\@defcolon#1{
    \catcode`\:\active
    \def:{\def\newline{\hfill\break\hspace*{2em}}{\@deactifygrammarchars #1}}
	\@makeother\:}

   \gdef\@defcomma#1{
    \catcode`\,\active
    \def,{\def\newline{\hfill\break\hspace*{4em}}{\@deactifygrammarchars #1}}
	\@makeother\,}

   \gdef\@defsemicolon#1{
    \catcode`\;\active
    \def;{\def\newline{\hfill\break\hspace*{2em}}{\@deactifygrammarchars #1}}
	\@makeother\;}

   \gdef\@defperiod#1{
    \catcode`\.\active
    \def.{\def\newline{\vskip10pt plus10pt minus5pt}{\@deactifygrammarchars #1}}
	\@makeother\.}

   \gdef\@defnonterminal#1{
    \catcode`\<\active
    \catcode`\>\active
    \def<{%
		\begingroup%
			\@first#1%
			\@deactifygrammarchars%
			\catcode`\>\active}
    \def>{%
			\@second#1%
		\endgroup}
	\@makeother\<
	\@makeother\>}

  \gdef\@defquote#1{
	\catcode`\"\active
    \def"{%
		\if@outsidestring%
			\@outsidestringfalse%
			\begingroup%
				\@deactifygrammarchars%
				\catcode`\"\active%
				\@first#1%
		\else%
				\@second#1%
			\endgroup%
			\@outsidestringtrue%
		\fi}
	\@makeother\"}

\endgroup

\let\@defterminal=\@defquote

\newenvironment{grammar}%
  {\begin{quote}%
   \@defaultchardefs%
   \@dogrammarchars}%
  {\@deactifygrammarchars%
   \end{quote}}

\def\@dogrammarchars{
  \@actifygrammarchars
  \@ifnextchar [{\@deactifygrammarchars\@getchardef}{}}

\def\@getchardef[(#1)#2]{
  \@dogrammarchar{#1}[#2]
  \@dogrammarchars}

\def\@dogrammarchar#1[#2]{
  \csname @def#1\endcsname{#2}}

\def\@defaultchardefs{
   \@defquote{{``}{''}}%
   \@defnonterminal{{$<$}{$>$}}%
   \@defcolon{:\\}%
   \@defsemicolon{;\\}%
   \@defperiod{.\\}%
   \@defcomma{, }}%