rulelinks.sty

%
% Hyperlinks in rule names:
%
%  The first time a rule name is used is presumed to be the definition
%  (probably in some figure with a bunch of rules).
%
%  Subsequent uses will be hyperlinks to the definition site.
%
% TODO:
%   Provide a way of using a rule name that doesn't establish that site
%   as the definition.
%

\ProvidesPackage{rulelinks}[2015/06/09 - First release]

\RequirePackage{mathpartir}

%
% \newrulecommand{Rulename}{MyName}
%
% Note: don't put a backslash in Rulename.
%

\newcommand{\newrulecommand}[2]{%
    \expandafter\newcommand\csname NoLink#1\endcsname{#2}%
    \expandafter\newcommand\csname #1\endcsname{%
        \ifcsname ZZRULE#1\endcsname%
            % Already defined:  Link to definition.
            %  "\expandafter...\endcsname" is what actually renders the rule,
            %   by invoking the \NoLink... version defined above.
            \hyperlink{rule:#1}{\expandafter\csname NoLink#1\endcsname}%
         %
        \else%
             % Not yet defined:  Declare a hypertarget.
             \hypertarget{rule:#1}{\expandafter\csname NoLink#1\endcsname}%
             \expandafter\gdef\csname ZZRULE#1\endcsname{}% Declare a macro so we go to the "Already defined" branch for subsequent uses
        \fi\xspace%
    }
}

%
% \newrulecommandONE: for rule names that take one argument (like \SumIntro{k}).
%
% \newrulecommandONE{Rulename}{MyName#1}
%
\newcommand{\newrulecommandONE}[2]{%
    \expandafter\newcommand\csname NoLink#1\endcsname[1]{#2}%
    \expandafter\newcommand\csname #1\endcsname[1]{%
        \ifcsname ZZRULE#1\endcsname%
            % Already defined:  Link to definition.
            %  "\expandafter...\endcsname" is what actually renders the rule,
            %   by invoking the \NoLink... version defined above.
            \hyperlink{rule:#1}{\expandafter\csname NoLink#1\endcsname{##1}}%
         %
        \else%
             % Not yet defined:  Declare a hypertarget.
             \hypertarget{rule:#1}{\expandafter\csname NoLink#1\endcsname{##1}}%
             \expandafter\gdef\csname ZZRULE#1\endcsname{}% Declare a macro so we go to the "Already defined" branch for subsequent uses
        \fi\xspace%
    }
}