\ProvidesPackage{wiki}[2008/07/02 v0.2 LaTeX through Wiki markup]
%% <- vorige Aenderungen gg�. 2008/06/25 verworfen 
%%
%% == Legal    == 
%% (C) 2008 Uwe Lueck http://contact-ednotes.sty.de.vu
%% License: http://www.latex-project.org/lppl/
%% -- AUTHOR-MAINTAINED, NO WARRANTY!
%%
%% == Features == 
%% 
%% The `wiki' package enables LaTeX users to use some of the 
%% markup used in editing Wikipedia pages, cf. 
%%
%%     http://en.wikipedia.org/wiki/Wikipedia:Cheatsheet
%%
%% or German:
%%
%%     http://de.wikipedia.org/wiki/Hilfe:Bearbeitungshilfe
%%     http://de.wikipedia.org/wiki/Hilfe:Textgestaltung
%% 
%% Advantages of such a kind of markup are: 
%%
%%  1. easier and faster to type than LaTeX code; 
%% 
%%  2. intuitive, understandable at a glance; 
%% 
%%  3. in reading the source code of the document, 
%%     the markup doesn't much distract from the ''text'' 
%%     to be printed. 
%%
%% There is a binary `easylatex' available on CTAN which is more 
%% powerful than the `wiki' package; the idea here is that a ''macro 
%% package'' doing something similar is easier to use and to customize. 
%%
%%
%% === What the Package Supports ===
%%
%% 1. ''Italics'' are marked up by surrounding pairs of apostrophes, 
%%    '''boldface''' needs one apostrophe more on each side. 
%%    Boldface and italics may be nested or overlap. 
%%    (This endangers quoting, but I have dealt with it.)
%%
%% 2. Surrounding ``equals'' symbols (`=') mark up section headings 
%%    etc.: `== Section ==', `=== Subsection ===', down to 
%%    `===== Subparagraph ====='. 
%%
%% 3. If a line starts with `*', it becomes an item in an 
%%    `itemize' environment. Likewise, `#' creates an `enumerate' 
%%    environment, and `;' makes an item in a `discription' 
%%    environment (differs from Wiki! -- since I don't understand
%%    what the Wiki version is good for). `:' makes a `quote' --
%%    while on Wikipedia instead is used for comments on talk 
%%    pages. But it is also used for indented math displays, 
%%    so it may be combined with $...$ here. 
%%    An indented line is typeset ''verbatim''. Each of these
%%    environments is ended by a code line without leading blank 
%%    spaces. 
%% 
%%
%% === Limitations ===
%%
%% 1. The markup ``language'' provided here replaces a few most 
%%    common LaTeX commands only in their most simple versions. 
%%    (Yet I think that already this makes the code more readable; 
%%     the more special cases are very rare.) E.g., it's not 
%%    possible to suppress the italic correction as with 
%%    `\textit{...\nocorr}'. However, in ``normal'' cases it 
%%    should be possible to use the more powerful LaTeX markup 
%%    mixed with ``Wiki'' markup. 
%%
%% 2. The parsing algorithms employed here differ in outcome to 
%%    those of Wikipedia in difficult cases. 
%% 
%% 3. Tables, nesting lists, links, Wiki templates and tags 
%%    are not supported -- and I don't expect that I can afford 
%%    improving this soon! 
%%
%% 4. I still have encountered problems that I didn't understand ...
%%
%% == Package Options and User Commands  ==
%%
%% \usepackage[<options>]{wiki}, of course. There are <options> 
%% `noEnvironments', `noFonts', `noHeadings' giving up 
%% functionality for lists etc., for italics and boldface, 
%% for section headings etc., respectively. 
%% 
%% There are commands \wikimarkup, \wikiEnvironments, 
%% \wikiFonts, \wikiHeadings to turn respective functionality on 
%% (unless disabled by package option). \nowikimarkup, 
%% \nowikiEnvironments, \nowikiFonts, \nowikiHeadings turn them 
%% off. 
%%
%% '''Vital:''' The package does ''not'' execute \wikimarkup 
%% because this would have strange effects, e.g., packages 
%% loaded later may break. The user must put activating 
%% commands into the `document' environment, maybe just preceding 
%% the first heading. 
%% 
%% Dangers to be avoided by \nowiki... are: 
%% * \wikiHeadings (which also is executed by \wikimarkup) 
%%   disables TeX assignments using `='. 
%% * \wikiEnvironments (executed by \wikimarkup) executes macros 
%%   at every end of a code line (containing no comment marke), 
%%   and it tries to typeset a following line verbatim if it is 
%%   indented. 
%% 
%%
%% == Implementation and Further Remarks == 

%% === Commands for Category Codes      === 
% \RequirePackage{fdcodes}
  %% <- TODO -- or do away ... -> 
\providecommand*\AssignCatCode[2]{\catcode`#1=#2\relax}
\providecommand*\MakeActive[1]{\catcode`#1=\active}
% \providecommand*\MakeLetter[1]{\catcode`#1=11\relax}
  %% <- Declaring characters usable in command strings
  %%    Todo: print arrow indicators like ``->'' as real arrows
\providecommand*\MakeOther [1]{\catcode`#1=12\relax}

\AssignCatCode{\_}{11} 
% \MakeLetter\_ %% own macros somewhat LaTeX3-style
%% Todo \newcommand <-> \def !?

%% === Package Options      ===
\DeclareOption{noFonts}       {\let\wikiFonts         \empty
                               \let\nowikiFonts       \relax}
\DeclareOption{noHeadings}    {\let\wikiHeadings      \empty
                               \let\nowikiHeadings    \relax}
\DeclareOption{noEnvironments}{\let\wikiEnvironments  \empty
                               \let\nowikiEnvironments\relax}
\DeclareOption{noVerbatim}{% 
  \def\W_active_return{ \futurelet\@let@token\W_on_firsttoken}}
  %% \[no]wikiVerbatim must wait, too complex 2008/07/01 
\ProcessOptions

%% === Auxiliaries for both Fonts and Headings ===

    \@tempswafalse 
    \ifx\wikiFonts   \empty \else \@tempswatrue \fi
    \ifx\wikiHeadings\empty \else \@tempswatrue \fi
    \if@tempswa
\def\W_start_samecnt{\futurelet\@let@token\W_process_samecnt}
\def\W_init_samecnt#1#2#3{%
  \let\W_samesymb  =#1%% repeated symbol 
  \def\W_repllist  {#2}% replacing strings
  \def\W_incase_all{#3}% final replacement
  \def\W_next##1{\W_start_samecnt}}
\def\W_process_samecnt{%
  \expandafter \W_splitlist \W_repllist \@nil
  \W_next} 
\def\W_splitlist#1#2\@nil{%
  \def\W_repllist{#2}%
  \ifx\@let@token\W_samesymb 
    \ifx\W_repllist\empty \def\W_next##1{\W_incase_all}\fi
  \else 
    \def\W_next{#1}%
  \fi}
    \fi 

%% === Italics and Boldface ===

%% ==== Code    ====
    \ifx\wikiFonts\empty \else 
\def\W_toggle#1#2#3{\def#1{\W_toggle#1{#3}{#2}}#2}
%% Cf. LaTeX's `\DeclareTextFontCommand':
\def\W_bf_toggle{%
  \W_toggle\W_bf_toggle{\bfseries\W_maybe@ic}{\mdseries\W_maybe@ic}}
\def\W_maybe@ic{\futurelet\@let@token\W_maybe_maybe@ic}
\def\W_maybe_maybe@ic{%
  \ifx\@let@token\W_rq_robust \else \expandafter \maybe@ic \fi}
\def\W_it_toggle{%
  \W_toggle\W_it_toggle{\itshape\maybe@ic}{\upshape\maybe@ic}}
%% <- Doesn't support \nocorr. 

\def\W_rq_robust{%% will become meaning of single right quote.
  \ifx\protect\@typeset@protect
    \ifmmode \rq \else 
      \W_init_samecnt{\W_rq_robust}%
                     {\rq\W_it_toggle}%
                     {\W_bf_toggle}%
      \expandafter\expandafter\expandafter \W_start_samecnt
    \fi
  \else \rq \fi}
%% Remark: 
%% LaTeX's \rq expands to ``other'' apostrophe: 
\CheckCommand*\rq{'} %% Must be before `\catcode`\'
%% \wikiFonts -- restoring `...' and ``...'' -- + \nowikiFonts: 
%% requiring single left quote \active as well: 
\CheckCommand*{\lq}{`}
\MakeActive\`\MakeActive\'
\def\wikiFonts{%
  \MakeActive\`\MakeActive\'%
  \def`##1'{\lq ##1\rq}%
  \let'\W_rq_robust}
\def\nowikiFonts{\MakeOther`\MakeOther\'}
\MakeOther\` \MakeOther\'
    \fi 

%% ==== Remarks ====
%% Wiki: a''b'''cd typesets `b' in italic with an apostrophe, 
%%       a''b'''c'''d typsets all after `a' in italic with bold `b'. 
%%       One might use make a difference depending on \lastskip. 
%%       Wikimedia seems to read more ahead, maybe entire paragraphs. 
%%       %% <- Todo: try here!? (Test!) 
%% 
%% Todo: Variants using \textit and \textbf (option, switching 
%%       command)
%%
%% german.sty's "` and "' are not affected. 
%%
%% Merit: ``...'' resembles ''...''; indeed Wikipedia Guidelines 
%%        demand to think which of both is appropriate in a
%%        certain situation. 

%% A test about \ifx with active characters: 
%\catcode`\`=\active \let`\rq \let'\rq
%\ifx`'\typeout{OHHH}\else \typeout{OCH}\fi  %% OHHH
%% <- how typeset code commented out!? (^!? diff. comment char.!?)
%%    indent %! TODO or no space after %!! TODO!! 
%%    xEDIT: dann Alt C/D fuer Kommentar/Dok./auskomm. (!?) !!

%% === Section Headings     ===

    \ifx\wikiHeadings\empty \else 
\providecommand*{\normalequals}{=}
\MakeActive\=
\def\wikiHeadings{\MakeActive\=\let=\W_eq_robust}
\def\nowikiHeadings{\MakeOther\=}
\def\W_eq_robust{%
  \ifx\protect\@typeset@protect 
  %% in case without math mode in heading
    \ifmmode \normalequals \else 
      \W_init_samecnt{\W_eq_robust}%
          {\normalequals\W_sec\W_subsec\W_subsubsec
           \W_para\W_subpara}%
          {\W_bf_toggle}%
      \expandafter\expandafter\expandafter \W_start_samecnt
    \fi
  \else \normalequals \fi}

\def\W_sec       #1=={\section{#1}}
\def\W_subsec    #1==={\subsection{#1}}
\def\W_subsubsec #1===={\subsubsection{#1}}
\def\W_para      #1====={\paragraph{#1}}
\def\W_subpara   #1======{\subparagraph{#1}}

\MakeOther\=
    \fi 

%% Todo: think of reimplementation by the start-line 
%%       mechanism which is going to be used for lists. 

%% === Environments         ===
%% 
    \ifx\wikiEnvironments\empty \else

%% ==== Prepare Dealing with Indents ====

\MakeActive{\^^M}%
\def\wikiEnvironments{\MakeActive{\^^M}\let^^M\W_active_return}%
\def\nowikiEnvironments{\AssignCatCode{\^^M}{5}}%
\nowikiEnvironments%% TeX <return> restored

\MakeActive{\ }%
\@ifundefined{W_active_return}{%
\expandafter\def\expandafter\W_active_return\expandafter{%
\space\catcode`\ \active\let \W_indent% 
%% <- \W_indent will start verbatim 
\futurelet\@let@token\W_on_firsttoken}%
}{}%% end of \@ifundefined which is true without noVerbatim
%% Much doubling for saving time (!??):
\expandafter\def\expandafter\W_list_activereturn\expandafter{%
\space\catcode`\ \active\let \W_restore_space% 
%% <- \W_indent will start verbatim 
\futurelet\@let@token\W_maybe_newitem}%
% \def\W_restore_space{\catcode`\ 10\relax}%
  %% <- was vital for a math display in a list ->
\def\W_restore_space{\catcode`\ 10\ignorespaces}%
\W_restore_space%% TeX blank space restored

%% ==== Start and End List-Like Environments ====

%% \W_on_firsttoken may be edited (preamble or .cfg):
\def\W_on_firsttoken{%
 %  \show\@let@token
  \W_restore_space
  \let\W_next\relax %% must be before \W_skip... works
  \ifx\@let@token\W_active_return \expandafter \W_par \fi
  %% <- found by guessing/with \show\@let@token
  \let\W_item\item
  \W_on_startenv{*}{itemize}%
  \W_on_startenv{\W_hash}{enumerate}%
  \W_on_startenv{;}{description}%
  \let\W_item\relax       %% must precede `quote'
  \W_on_startenv{:}{quote}%% instead of quotation 2008/07/01
  \W_next}
\let\W_hash=#
\def\W_par#1\W_next{\par}
\def\W_skiprest_item#1\W_next#2{\W_item}

\MakeActive{\^^M}%
\def\W_on_startenv#1#2{% 
  \ifx#1\@let@token%
    \begin{#2}% 
      \let\W_itemsymbol#1%
      \let^^M\W_list_activereturn%
      \expandafter \W_skiprest_item%
  \fi}%
\nowikiEnvironments%

\def\W_maybe_newitem{% 
  \W_restore_space
  \ifx\@let@token\W_itemsymbol 
    \expandafter \W_gobbling_item 
  \else 
    \ifx\@let@token\W_restore_space 
    \else 
      \ifx\@let@token\W_list_activereturn 
        \par 
      \else
        \edef\W_next{\noexpand\end{\@currenvir}}%
        \W_next
      \fi
    \fi
  \fi}
\def\W_gobbling_item#1{\item}

%% ==== Verbatim Environment         ====

\def\W_indent{\begin{W_verbatim}}
\def\W_verbatim{%
  \let\obeylines\W_obeylines
  \@verbatim \frenchspacing\@vobeyspaces}
\let\endW_verbatim\endverbatim

\MakeActive{\^^M}
\def\W_obeylines{% 
  \catcode`\^^M\active%
  \def^^M{\par\futurelet\@let@token\W_check_verbcont}}%
\nowikiEnvironments%

\def\W_check_verbcont{% 
  \ifx\@let@token\@xobeysp 
    \expandafter \@gobble %% gobble one space
  \else 
    \def\W_next{\end{W_verbatim}}%
    \expandafter \W_next
  \fi}

%% TODO: enable user to switch between environment ``encodings'' 
%%       or to disable some of them (edit \W_on_firsttoken)

    \fi %% from \ifx\wikiEnvironments \else


%% === Turning Wiki Markup On and Off ===

\def\wikimarkup{\wikiFonts\wikiHeadings\wikiEnvironments}
\def\nowikimarkup{%
  \MakeOther\`\MakeOther\'\MakeOther\=\AssignCatCode{\^^M}{5}}

% \wikimarkup %% strange effects here, to be put into document

\AssignCatCode\_{8} 
\endinput

%% todo: tables, links, templates, (pseudo-)html-tags ... 
%% TODO: credits: easylatex etc. 
%% TODO: useful for: ... intuitive markup, ``poor man's WYSIWYG'', 
%%       ASCII-WYSIWYG. 
%% Todo: improve Wiki markup: ``tab'' indents instead of `:'
%%       as in testing for end of list: after finding one 
%%       leading space, test for another.