% !TeX root = selnolig.tex
% !TEX TS-program = lualatex

% This entire package is placed under the terms of the
% LaTeX Project Public License, version 1.3 or later
% (http://www.latex-project.org/lppl.txt).
% It has the status "maintained".
%
% Author: Mico Loretan (loretan dot mico at gmail dot com)


% Part 1: Preliminaries
% ---------------------

\def\selnoligpackagename{selnolig}
\def\selnoligpackageversion{0.250}
\def\selnoligpackagedate{2013/06/30}

% Announce who we are. Issue warning message if we're
% not running under LuaLaTeX.

\typeout{=== Package \selnoligpackagename, 
             Version \selnoligpackageversion, 
             Date    \selnoligpackagedate ===}
\ProvidesPackage{selnolig}[\selnoligpackagedate]

\RequirePackage{ifluatex}

\ifluatex
  \RequirePackage{luatexbase,luacode,expl3}
\else
  \typeout{ ======================================= }
  \typeout{      WARNING   WARNING    WARNING       }
  \typeout{ --------------------------------------- }
  \typeout{ The ligature suppression macros of the  }
  \typeout{ selnolig package *require* LuaLaTeX.    }
  \typeout{ Because you're NOT running this package }
  \typeout{ under LuaLaTeX, ligature suppression    }
  \typeout{ *can not* be performed.                 }
  \typeout{=========================================}
\fi

% If the 'fontspec' package isn't loaded by the time
% the '\begin{document}' directive is encoutered, issue
% an error message and exit. 

\AtBeginDocument{%
\ifluatex
  \@ifpackageloaded{fontspec}{}{%  
  \PackageError{selnolig}{%
     ========================================== \MessageBreak
          Error Alert      Error Alert          \MessageBreak
     ------------------------------------------ \MessageBreak
     The selnolig package *requires* the        \MessageBreak
     'fontspec' package, but it hasn't been     \MessageBreak
     loaded. Exiting now.                       \MessageBreak
     ===========================================}
  }
\fi
}

% Set up some fundamental Boolean variables, their
% default values, and define the user options.

% The main language options are 'english' and 'german'.
% We provide the option 'otherlang' option just in case
% a user wants to provide ligature suppression patterns 
% for languages other than English and German.

\newif\if@english\@englishfalse
\newif\if@german\@germanfalse
\newif\if@otherlang\@otherlangfalse

\DeclareOption{english}{\@englishtrue}
% synonymous options:
  \DeclareOption{usenglish}{\@englishtrue}
  \DeclareOption{ukenglish}{\@englishtrue}
  \DeclareOption{USenglish}{\@englishtrue}
  \DeclareOption{UKenglish}{\@englishtrue}
  \DeclareOption{american}{\@englishtrue}
  \DeclareOption{british}{\@englishtrue}
  \DeclareOption{canadian}{\@englishtrue}
  \DeclareOption{australian}{\@englishtrue}
  \DeclareOption{newzealand}{\@englishtrue}

\DeclareOption{ngerman}{\@germantrue}
% synonymous options:
  \DeclareOption{german}{\@germantrue}
  \DeclareOption{austrian}{\@germantrue}
  \DeclareOption{naustrian}{\@germantrue}
  \DeclareOption{swiss}{\@germantrue}
  \DeclareOption{swissgerman}{\@germantrue}

\DeclareOption{otherlang}{\@otherlangtrue}
% synonymous option:
  \DeclareOption{otherlanguage}{\@otherlangtrue}


% For English, the default is to load only a fairly basic
% set of non-ligation rules pertaining to f-ligatures.
% Among them are the "standard five" (ff, fi, fl, ffi,
% and ffl) ligatures as well as the ft ligature.
%
% Two options to override this "basic" setting:
% - broadf  Many more non-ligation rules for f-ligatures,
%            incl. fb, fh, fj, and fk character pairs.
% - hdlig    Additional ligature suppression rules for 
%            'historic' and/or 'discretionary' ligatures, 
%            e.g., ct, sp, st, sk, th, as, is, us, fr, 
%            ll, et, at, and ta.

\newif\if@broadfset\@broadfsetfalse
\DeclareOption{broadf}{\@broadfsettrue}

\newif\if@hdligset\@hdligsetfalse 
\DeclareOption{hdlig}{\@hdligsettrue}


% The package also provides hyphenation exception 
% patterns for English and German language words. 
% Loading these patterns is enabled by default. This
% can be disabled by providing the option
% 'noadditionalhyphenationpatterns'.

\newif\if@addlhyph\@addlhyphtrue
\DeclareOption{noadditionalhyphenationpatterns}{\@addlhyphfalse}


% The 'basic' option automatically sets the preceding 
% Booleans to 'false', even if historic and/or rare 
% ligatures are enabled

\DeclareOption{basic}{\@broadfsetfalse\@hdligsetfalse}


% The option 'noftligs' serves to suppress ft and fft
% ligatures *globally*; default value: 'false'.

\newif\if@noftligs\@noftligsfalse
\DeclareOption{noftligs}{\@noftligstrue}


% Finally, an option to set most language-related 
% Boolean variables (other than '@addlhyph') to 
% 'true' simultaneously.

\DeclareOption{all}{%
   \@englishtrue \@broadfsettrue \@hdligsettrue
   \@germantrue \@otherlangtrue}

% Finally, process all options
\ProcessOptions\relax

\if@noftligs{% % suppress ft and fft ligatures globally
  \AtBeginDocument{ \nolig{ft}{f|t} }
\fi


% Part 2: Load the lua code and set up the user macros
% ----------------------------------------------------

\ifluatex 
  % Load the lua code contained in 'selnolig.lua'.
  \directlua{  require("selnolig.lua")  }
  
  % Commands to switch selnolig's routines on and off
  \newcommand\selnoligon{%
    \directlua{ enableselnolig() }%
  }

  \newcommand\selnoligoff{%
    \directlua{ disableselnolig() }%
  }
  
  % By default, selnolig's macros are switched on
  \selnoligon
  
  
  % Record operations of selnolig package to the log 
  % file: Enabled via '\debugon' command
  \newcommand\debugon{%
     \directlua{ debug=true }
  }
  \newcommand\debugoff{% 
     \directlua{ debug=false }
  }


  % The first main user macro is called '\nolig':
  \newcommand\nolig[2]{
     \directlua{
        suppress_liga( "\luatexluaescapestring{#1}",
                       "\luatexluaescapestring{#2}" )
     }
  }
  
  % A second user macro allows global overriding of
  % rules set by \nolig instructions:
  \newcommand\keeplig[1]{
     \directlua{
        always_keep_liga( "\luatexluaescapestring{#1}" )
     }
  }

  % A third user macro turns ligature suppression
  % off temporarily:
  \newcommand\uselig[1]{%
    \directlua{ enable_suppression(false) }%
    \mbox{#1}%
    \directlua{ enable_suppression(true) }%
  }


\else
  % If *not* running under LuaLaTeX, provide dummy
  % definitions for package's user macros.
  \newcommand{\nolig}[2]{}
  \newcommand{\keeplig}[1]{}
  \newcommand{\uselig}[1]{\mbox{#1}}
  \let\selnoligon\relax
  \let\selnoligoff\relax
  \let\debugon\relax
  \let\debugoff\relax
\fi


% A fourth user macro: '\breaklig'. This is hopefully 
% easier to remember than having to type "\-\hspace{0pt}".
% (It's defined outside the \ifluatex conditional since
% it doesn't use any lua code.)

\newcommand\breaklig{\-{\hspace{0pt}}}


% Part 3: What to do if the 'english' option is set
% -------------------------------------------------

\if@english
   % load English-language ligature suppression rules
   \ifluatex
      \RequirePackage{selnolig-english-patterns}
   \fi

   % load additional hyphenation exception patterns
   \if@addlhyph
      \RequirePackage{selnolig-english-hyphex}
   \fi
\fi


% Part 4: What to do if the 'ngerman' option is set
% -------------------------------------------------

\if@german
   % load German-language ligature suppression rules
   \ifluatex
      \RequirePackage{selnolig-german-patterns}
   \fi

   % load additional hyphenation exception patterns
   \if@addlhyph
      \RequirePackage{selnolig-german-hyphex}
   \fi
\fi


% Part 5: What to do if the 'otherlang' option is set
% ---------------------------------------------------

\if@otherlang
    % currently nothing included
\fi