protocol.sty

%----------------------------------------------------------------------
% this is: protocol.sty   v1.3   93/09/06   Peter de Rooij
%----------------------------------------------------------------------
% Modified by Juan Garay to support broken arrows 
% Modified by Mihir to add a new macro protocolm which has an extra
% left hand side column for flow names. July 7, 1995.
%----------------------------------------------------------------------
% ARROWFILL WITH \textstyle SUPERSCRIPT.
% use in math-mode:
%  \sends{a^b} makes a `rightarrowfill' with $a^b$ on top.
%  \Sends[n]{a^b} idem but spans n columns
%  \receives{a^b}, \Receives[n]{a^b}  idem for leftarrowfill
%  \exchange{a^b}, \Exchange[n]{a^b}  idem for lefrightarrowfill
%
%  \bsends (resp., \bSends) and \breceives (resp., \bReceives) produce
%          broken-line versions of sends & receives
%  \dsends (resp., \dSends) and \dreceives (resp., \dReceives) produce
%          double-line versions of sends & receives
%  \tsends (resp., \tSends) and \treceives (resp., \tReceives) produce
%          triple-line versions of sends & receives
%----------------------------------------------------------------------


\newcommand{\Pdash}{\begin{picture}(6,4)
\thinlines\put(0,2){\line(1,0){6}}\end{picture}}
\newcommand{\Pdotteddash}{\begin{picture}(10,4)
\thinlines\put(0,2){\line(1,0){5}}\end{picture}}
\newcommand{\Prightarrow}{\begin{picture}(6,4)
\thinlines\put(0,2){\vector(1,0){6}}\end{picture}}
\newcommand{\Pleftarrow}{\begin{picture}(6,4)
\thinlines\put(6,2){\vector(-1,0){6}}\end{picture}}

\newcommand{\Pdoubledash}{\begin{picture}(6,10)
\thinlines\put(0,2){\line(1,0){6}}
\put(0,8){\line(1,0){6}}
\end{picture}}
\newcommand{\Pdoubleleftarrow}{\begin{picture}(12,10)
\thinlines\put(5,2){\line(1,0){8}}
\put(5,8){\line(1,0){8}}
\put(0,5){\line(3,2){10}}
\put(0,5){\line(3,-2){10}}
\end{picture}}
\newcommand{\Pdoublerightarrow}{\begin{picture}(12,10)
\thinlines\put(7,2){\line(-1,0){8}}
\put(7,8){\line(-1,0){8}}
\put(12,5){\line(-3,2){10}}
\put(12,5){\line(-3,-2){10}}
\end{picture}}

\newcommand{\Ptripledash}{\begin{picture}(6,8)
\thinlines\put(0,2){\line(1,0){6}}
\put(0,4){\line(1,0){6}}
\put(0,6){\line(1,0){6}}
\end{picture}}

\newcommand{\Ptriplerightarrow}{\begin{picture}(12,8)
    \thinlines\put(0,2){\vector(1,0){12}}
    \thinlines\put(12,4){\line(-1,0){12}}
    \thinlines\put(0,6){\vector(1,0){12}}
\end{picture}}
\newcommand{\Ptripleleftmidarrow}{\begin{picture}(12,8)
    \thinlines\put(0,2){\line(1,0){12}}
    \thinlines\put(12,4){\vector(-1,0){12}}
    \thinlines\put(0,6){\line(1,0){12}}
\end{picture}}

\newcommand{\Ptripleleftarrow}{\begin{picture}(12,8)
    \thinlines\put(12,2){\vector(-1,0){12}}
    \thinlines\put(0,4){\line(1,0){12}}
    \thinlines\put(12,6){\vector(-1,0){12}}
\end{picture}}
\newcommand{\Ptriplerightmidarrow}{\begin{picture}(12,8)
    \thinlines\put(12,2){\line(-1,0){12}}
    \thinlines\put(0,4){\vector(1,0){12}}
    \thinlines\put(12,6){\line(-1,0){12}}
\end{picture}}

% \newcommand{\Ptwowaysuperarrow}{\begin{picture}(74,4)
% \thinlines\put(72,2){\vector(-1,0){72}}
% \thinlines\put(2,2){\vector(1,0){72}}\end{picture}}


% shorthand for lowering the arrows
\def\@r@al{\raise\arrowlower}

% rulefill made up of lowered $-$'s
\def\@lrulefill{\cleaders\hbox{$\mkern-2mu\@r@al\hbox{\Pdash}\mkern-2mu$}\hfill}

% broken rulefill made up of lowered $-~$'s
\def\@blrulefill{\cleaders\hbox{$\mkern-2mu\@r@al\hbox{\Pdotteddash}\mkern-2mu$}\hfill}
%\def\@blrulefill{\cleaders\hbox{$\mkern-2mu\@r@al\hbox{\rule{0.1cm}{0.1cm}}\mkern-2mu$}\hfill}

% double rulefill made up of lowered $=$'s
\def\@dlrulefill{\cleaders\hbox{$\mkern-3mu\@r@al\hbox{\Pdoubledash}\mkern-3mu$}\hfill}

% triple rulefill made up of lowered triple dashes
\def\@tlrulefill{\cleaders\hbox{$\mkern-3mu\@r@al\hbox{\Ptripledash}\mkern-3mu$}\hfill}

% end of rule (overlaps with arrowheads):
\def\@lendofrule{\@r@al\hbox{\Pdash}\mkern-4mu} 
\def\@rendofrule{\mkern-4mu\@r@al\hbox{\Pdash}} 

% double end of rule (overlaps with arrowheads):
\def\@dlendofrule{\@r@al\hbox{\Pdoubledash}\mkern-4mu} 
\def\@drendofrule{\mkern-4mu\@r@al\hbox{\Pdoubledash}} 

% triple end of rule (overlaps with arrowheads):
\def\@tlendofrule{\@r@al\hbox{\Ptripledash}\mkern-4mu} 
\def\@trendofrule{\mkern-4mu\@r@al\hbox{\Ptripledash}} 

% ends of arrows:
\def\@rafill{\mkern-6mu\@lrulefill\@rendofrule\@r@al\llap{\Prightarrow}}
\def\@lafill{\m@th\@r@al\rlap{\Pleftarrow}\@lendofrule\@lrulefill\mkern-6mu}
\def\@rdfill{\mkern-6mu\@lrulefill\@rendofrule}
\def\@ldfill{\m@th\@lendofrule\@lrulefill\mkern-6mu}

% ends of broken arrows:
\def\@brafill{\mkern-6mu\@blrulefill\@rendofrule\@r@al\llap{\Prightarrow}}
\def\@blafill{\m@th\@r@al\rlap{\Pleftarrow}\@lendofrule\@blrulefill\mkern-6mu}
\def\@brdfill{\mkern-6mu\@blrulefill\@rendofrule}
\def\@bldfill{\m@th\@lendofrule\@blrulefill\mkern-6mu}

% ends of double arrows:
\def\@drafill{\mkern-6mu\@dlrulefill\@r@al\hbox{\Pdoublerightarrow}}
\def\@dlafill{\m@th\@r@al\hbox{\Pdoubleleftarrow}\@dlrulefill\mkern-6mu}
\def\@drdfill{\mkern-6mu\@dlrulefill\@drendofrule}
\def\@dldfill{\m@th\@dlendofrule\@dlrulefill\mkern-6mu}
% \def\@drafill{\mkern-6mu\@dlrulefill\@drendofrule\@r@al\llap{\Pdoublerightarrow}}
% \def\@dlafill{\m@th\@r@al\rlap{\Pdoubleleftarrow}\@dlendofrule\@dlrulefill\mkern-6mu}

% ends of triple arrows:
\def\@trafill{\mkern-6mu\@tlrulefill\@r@al\hbox{\Ptriplerightarrow}}
\def\@tlafill{\m@th\@r@al\hbox{\Ptripleleftarrow}\@tlrulefill\mkern-6mu}
\def\@trdfill{\mkern-6mu\@tlrulefill\@r@al\hbox{\Ptriplerightmidarrow}}
\def\@tldfill{\m@th\@r@al\hbox{\Ptripleleftmidarrow}\@tlrulefill\mkern-6mu}
%\def\@trdfill{\mkern-6mu\@tlrulefill\@trendofrule}
%\def\@tldfill{\m@th\@tlendofrule\@tlrulefill\mkern-6mu}

% ends of thick arrows:
%\def\@brafill{\mkern-6mu\@blrulefill\@rendofrule\@r@al\llap{$\rightarrow$}}
%\def\@blafill{\m@th\@r@al\rlap{$\lhd$}\@lendofrule\@blrulefill\mkern-6mu}
%\def\@brdfill{\mkern-6mu\@blrulefill\@rendofrule}
%\def\@bldfill{\m@th\@lendofrule\@blrulefill\mkern-6mu}

\newdimen\minarrowwidth   \minarrowwidth=0pt
\newdimen\arrowwidth
\newdimen\arrowlower      \arrowlower=-4pt

\def\@showmessage#1{\setbox\@tempboxa\hbox{$#1$}
  \ifdim\wd\@tempboxa<\minarrowwidth 
    \arrowwidth\minarrowwidth 
  \else 
    \arrowwidth\wd\@tempboxa 
  \fi
  \hbox{$\m@th\displaystyle\mathop{\hbox to \arrowwidth
    {$\m@th\@lrulefill$}}\limits^{\hfill\box\@tempboxa\hfill}$}}

% for broken arrows
\def\@bshowmessage#1{\setbox\@tempboxa\hbox{$#1$}
  \ifdim\wd\@tempboxa<\minarrowwidth 
    \arrowwidth\minarrowwidth 
  \else 
    \arrowwidth\wd\@tempboxa 
  \fi
  \hbox{$\m@th\displaystyle\mathop{\hbox to \arrowwidth
    {$\m@th\@blrulefill$}}\limits^{\hfill\box\@tempboxa\hfill}$}}


% for double arrows
\def\@dshowmessage#1{\setbox\@tempboxa\hbox{$#1$}
  \ifdim\wd\@tempboxa<\minarrowwidth 
    \arrowwidth\minarrowwidth 
  \else 
    \arrowwidth\wd\@tempboxa 
  \fi
  \hbox{$\m@th\displaystyle\mathop{\hbox to \arrowwidth
    {$\m@th\@dlrulefill$}}\limits^{\hfill\box\@tempboxa\hfill}$}}

% for triple arrows
\def\@tshowmessage#1{\setbox\@tempboxa\hbox{$#1$}
  \ifdim\wd\@tempboxa<\minarrowwidth 
    \arrowwidth\minarrowwidth 
  \else 
    \arrowwidth\wd\@tempboxa 
  \fi
  \hbox{$\m@th\displaystyle\mathop{\hbox to \arrowwidth
    {$\m@th\@tlrulefill$}}\limits^{\hfill\box\@tempboxa\hfill}$}}

\def\sends{\@sends}
\def\Sends[#1]#2{\multispan{#1}$\@sends{#2}$}
\def\@sends#1{\@ldfill\@showmessage{#1}\@rafill}

% broken send
\def\bsends{\@bsends}
\def\bSends[#1]#2{\multispan{#1}$\@bsends{#2}$}
\def\@bsends#1{\@bldfill\@bshowmessage{#1}\@brafill}

% double send
\def\dsends{\@dsends}
\def\dSends[#1]#2{\multispan{#1}$\@dsends{#2}$}
\def\@dsends#1{\@dldfill\@dshowmessage{#1}\@drafill}

% triple send
\def\tsends{\@tsends}
\def\tSends[#1]#2{\multispan{#1}$\@tsends{#2}$}
\def\@tsends#1{\@tldfill\@tshowmessage{#1}\@trafill}
 
\def\receives{\@receives}
\def\Receives[#1]#2{\multispan{#1}$\@receives{#2}$}
\def\@receives#1{\@lafill\@showmessage{#1}\@rdfill}

% broken receive
\def\breceives{\@breceives}
\def\bReceives[#1]#2{\multispan{#1}$\@breceives{#2}$}
\def\@breceives#1{\@blafill\@bshowmessage{#1}\@brdfill}

% double receive
\def\dreceives{\@dreceives}
\def\dReceives[#1]#2{\multispan{#1}$\@dreceives{#2}$}
\def\@dreceives#1{\@dlafill\@dshowmessage{#1}\@drdfill}
 
% triple receive
\def\treceives{\@treceives}
\def\tReceives[#1]#2{\multispan{#1}$\@treceives{#2}$}
\def\@treceives#1{\@tlafill\@tshowmessage{#1}\@trdfill}
 
\def\exchange{\@exchange}
\def\Exchange[#1]#2{\multispan{#1}$\@exchange{#2}$}
\def\@exchange#1{\@lafill\@showmessage{#1}\@rafill}

%----------------------------------------------------------------------
% NARROWING COLUMNS
% \narrowcol{ARG} produces ARG centered in an \hbox that is 2em too
% narrow for its contents. ARG is still in math-mode!
% \Narrowcol does the same with the double amount of shrinking.
% \phantomcol does the same with a column of zero width
% BUG: cannot be used for \send and relatives!

\def\narrowcol#1{\hbox{\hskip-1em$#1$\hskip-1em}}
\def\Narrowcol#1{\hbox{\hskip-2em$#1$\hskip-2em}}
\def\phantomcol#1{\hbox to 0pt{\hss$#1$\hss}}

%----------------------------------------------------------------------
% A PROTOCOL ENVIRONMENT. 
% args: #1: number of parties
% essentially, an array with # columns depending on the argument.
% furthermore, a macro \participants with the correct number of args 
% is defined. \participants{A}{B}[{C}...] puts A resp. B (and C...) centered 
% over columns 1 resp. 3 (resp. 5...)
% BUG: PARTICIPANTS CAN BE USED ONLY ONCE PER PROTOCOL!
% \protocolheader{#1} puts #1 in an \hbox centered over the entire
% array.
%
% use: 
%  \begin{protocol}{2}
%    \protocolheader{HEADER}\\
%    \participants{Alice}{Bob}\\
%    y := x^2\\
%       & \sends{y}\\
%       &       & \mbox{verify if $y=x^2$}\\
%       & \receives{\mbox{OK!}}\\
%    \mbox{be happy}
%  \end{protocol}       
%  yields:
%                 HEADER
%
%      Alice                 Bob
%
%       y=x^2
%               y
%            ------>
%                     verify if $y=x^2$
%              OK!
%            <------
%    be happy
%
\newcount\@ncols    \@ncols=3
\newcount\@nccols   \@nccols=1
\newcount\@nparties \@nparties=2
\newcount\@npartic 

\def\protocolheader#1{\multicolumn{\the\@ncols}{c}{\hbox{#1}}\\}
\def\participants{% initialize:
  \noalign{\global\@npartic\@nparties\gdef\@more{}}
  % and do the real stuff:
  \@participants}
\def\@participants#1{% print next participant:
  \@more\multicolumn{1}{c}{\hbox{#1}}
  % next time, first put in &&:
  \gdef\@more{&&}
  \global\advance\@npartic by \m@ne
  % if there's more to do:
  \ifnum\@npartic>0 \let\next\@participants
  \else\let\next\\\fi\next
}

\newenvironment{protocol}[1]{% arg: # of parties
  \relax\ifnum #1 < 2 
    \typeout{Only n-party protocols for n>1 implemented!}
    \typeout{I'll assume n=2.}
    \@nparties=2
  \else
    \@nparties=#1
  \fi 
  % # of cols = 2 * (# of parties) - 1
  \@ncols = \@nparties 
  \multiply \@ncols by 2 
  \advance \@ncols by -1
  % # of centered cols = 2 * (# of parties) - 3
  \@nccols = \@ncols
  \advance \@nccols by -2
  % arrowwidth based on # of columns:
  \minarrowwidth = .5\textwidth 
  \divide\minarrowwidth by \@ncols
  % lower all arrows halfway down to baseline:
  \setbox\@tempboxa\hbox{$\leftarrow$}
  \arrowlower-.5\ht\@tempboxa
  $\begin{array}{r*{\@nccols}{c}l}
}{\end{array}$}

\newenvironment{protocolm}[1]{% arg: # of parties
  \relax\ifnum #1 < 2 
    \typeout{Only n-party protocols for n>1 implemented!}
    \typeout{I'll assume n=2.}
    \@nparties=2
  \else
    \@nparties=#1
  \fi 
  % # of cols = 2 * (# of parties) - 1
  \@ncols = \@nparties 
  \multiply \@ncols by 2 
  \advance \@ncols by -1
  % # of centered cols = 2 * (# of parties) - 3
  \@nccols = \@ncols
  \advance \@nccols by -2
  % arrowwidth based on # of columns:
  \minarrowwidth = .5\textwidth 
  \divide\minarrowwidth by \@ncols
  % lower all arrows halfway down to baseline:
  \setbox\@tempboxa\hbox{$\leftarrow$}
  \arrowlower-.5\ht\@tempboxa
  $\begin{array}{lr*{\@nccols}{c}l}
}{\end{array}$}

\endinput
-- 
Peter de Rooij                  <P.J.N.deRooij@research.ptt.nl>
It's better to regret something you have done, 
than to regret something you haven't done.              -- Butthole Surfers