% Copyright 2012-2022, Alexander Shibakov
% This file is part of SPLinT
%
% SPLinT is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% SPLinT is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with SPLinT.  If not, see <http://www.gnu.org/licenses/>.

% the sequences in this file have the eventual goal of implementing macros that count and compare token sequences
% (as either parameters or contents of token registers) in expandable manner.
% currently, a new sequence is prepared first, consisting of `markers'
% that indicate whether the token in the coresponding position of the
% original sequence is a potential blank space or brace (closing or
% opening);
% the macros then make the determination about the last possible blank
% on whether this is a true space or not; the goal is to make this
% macro independent of the value of \escapechar
% 
% as of now the implementation is far from refined although an expandable conting macro
% can be easily produced

\catcode`\@=11
\input ../../tex/yycommon.sty
\input ../../tex/yymisc.sty

%%%%%%%%%%%%% the material before this point should be included from appropriate files

% #1 -- `call stack'
% #2 -- remaining sequence
% #3 -- `parsed' sequence

\def\yypreparsetokensequenc@#1#2#3{%
    \yystringempty{#2}{#1{#3}}{\yypreparsetokensequen@@{#1}{#2}{#3}}%
}

\def\yypreparsetokensequen@@#1#2#3{% remaining sequence is nonempty
    \yystartsinbrace{#2}{\yydealwithbracedgroup{#1}{#2}{#3}}{\yypreparsetokensequ@n@@{#1}{#2}{#3}}%
}

\def\yydealwithbracedgroup#1#2#3{% the first token of the remaining sequence is a brace
    \iffalse{\fi\yydealwithbracedgro@p#2}{#1}{#3}%
}

\def\yydealwithbracedgro@p#1{%
    \yypreparsetokensequenc@{\yyrepackagesequence}{#1}{}%
}

% #1 -- parsed sequence
% this is a sequence to `propagate expansion' into the next parameter.
% the same can be achieved by packaging the whole sequence with a 
% \csname ... \endcsname pair and using a simple \expandafter

\def\yyrepackagesequence#1{%
    \yyrepackagesequenc@{}#1\end
}

% #1 -- `packaged' sequence (\expandafter\expandafter\expandafter ? ...)
% #2 -- the next category 12 character or \end

\def\yyrepackagesequenc@#1#2{%
    \ifx#2\end
        \yybreak{\yyrepackagesequ@nc@{#1\expandafter\expandafter\expandafter}}%
    \else
        \yybreak{\yyrepackagesequenc@{#1\expandafter\expandafter\expandafter#2}}%
    \yycontinue
}

% #1 -- `packaged' sequence (\expandafter\expandafter\expandafter ? ...)
% this macro is followed by the remainder of the original sequence with a so far
% unmatched right brace, the `call stack' and the parsed sequence.

\def\yyrepackagesequ@nc@#1{%
    \expandafter\expandafter\expandafter\yyrepackagesequ@nc@swap#1{\expandafter\eatone\string}%
}

% #1 -- parsed sequence without packaging

\def\yyrepackagesequ@nc@swap#1#{%
    \yyrepackagesequ@nc@sw@p{#1}%
}

% #1 -- parsed `inner' sequence
% #2 -- remainder of the original sequence
% #3 -- `call stack'
% #4 -- parsed sequence so far

\def\yyrepackagesequ@nc@sw@p#1#2#3#4{%
    \yypreparsetokensequenc@{#3}{#2}{#4[#1]}%
}

% `braced group' thread ends here

% #1 -- `call stack'
% #2 -- remaining sequence
% #3 -- `parsed' sequence

\def\yypreparsetokensequ@n@@#1#2#3{% the remaining group in #2 is nonempty and does not start with a brace
    \yystartsinspace{#2}{\yyconsumetruespace{#1}{#2}{#3}}{\yypreparsetokenseq@@n@@{#1}{#2}{#3}}%
}

\def\yyconsumetruespace#1#2#3{%
    \expandafter\yyconsumetruespac@swap\expandafter{\eatonespace#2}{#1}{#3.}%
}

\def\yyconsumetruespac@swap#1#2#3{%
    \yypreparsetokensequenc@{#2}{#1}{#3}%
}

% `group starting with a true (character code 32, category code 10) space' thread ends here

% #1 -- `call stack'
% #2 -- remaining sequence
% #3 -- `parsed' sequence

\def\yypreparsetokenseq@@n@@#1#2#3{% a nonempty group, that does not start with a brace or a true space
    \yymatchblankspace{#2}{\yyrescanblankspace{#2}{#1}{#3}}{\yypreparsetokens@q@@n@@{#1}{#2}{#3}}%
}

% #1 -- remaining sequence
% #2 -- `call stack'
% #3 -- `parsed' sequence

\def\yyrescanblankspace#1#2#3{%
    \expandafter\expandafter\expandafter
        \yyrescanblankspac@swap
    \expandafter\expandafter\expandafter{\expandafter\yynormalizeblankspac@\meaning#1}{#2}{#3*}%
}

\def\yyrescanblankspac@swap#1#2#3{%
    \yystartsinspace{#1}{%
        \expandafter\yyrescanblankspac@sw@p\expandafter{\eatonespace#1}{#2}{#3}%
    }{%
        \expandafter\yyrescanblankspac@sw@p\expandafter{\eatone#1}{#2}{#3}%
    }%
}

\def\yyrescanblankspac@sw@p#1#2#3{%
    \yypreparsetokensequenc@{#2}{#1}{#3}%
}

% `group starting with a blank space' ends here

% #1 -- `call stack'
% #2 -- remaining sequence
% #3 -- `parsed' sequence

\def\yypreparsetokens@q@@n@@#1#2#3{% nonempty group starting with a non blank, non brace token
    \expandafter\yypreparsetokens@q@@n@@swap\expandafter{\eatone#2}{#1}{#30}%
}

\def\yypreparsetokens@q@@n@@swap#1#2#3{%
    \yypreparsetokensequenc@{#2}{#1}{#3}%
}

% #1 -- `call stack'
% #2 -- remaining sequence
% #3 -- `parsed' sequence

\def\yydebracesequence#1#2#3{%
    \yybracesleft#3[\end{#1}{#2}%
}

% #1 -- tokens preceding the brace
% #2 -- tokens following the brace
% #3 -- `call stack'
% #4 -- remaining sequence

\def\yybracesleft#1[#2\end#3#4{%
    \if9#29%
        \yybreak{\yyfirstoftwo}%
    \else
        \yybreak{\yysecondoftwo}%
    \yycontinue{#3{#4}}{\yydebracesequenc@swap{#4}{#3}{#1#2}}%
}

\def\yydebracesequenc@swap#1#2#3{%
    \expandafter\expandafter\expandafter
        \yydebracesequenc@sw@p
    \expandafter\expandafter\expandafter{\yygrabprebrace#1}{#2}{#3}%
}

\def\yydebracesequenc@sw@p#1#2#3{%
    \yydebracesequ@nc@sw@p#3\end{#1}{#2}%
}

\def\yydebracesequ@nc@sw@p#1[\end#2#3{%
    \yydebracesequence{#3}{#2}{#1}%
}
\def\yygrabprebrace#1#{%
    \yygrabprebrac@{#1}%
}

\def\yygrabprebrac@#1#2{#1#2}

% the `debracing group' ends here

% string comparison macros below are woefully inefficient and can be replaced by a much
% shorter and faster version; they are easy to analyze, though;

% #1 -- string of category code 12 or 10 characters
% #2 -- string of category code 12 or 10 characters

\def\yycomparesimplestrings#1#2{%
    \yystringempty{#1}{%
        \yystringempty{#2}{\yyfirstoftwo}{\yysecondoftwo}%
    }{\yycomparesimplestrings@{#1}{#2}}%
}

\def\yycomparesimplestrings@#1#2{% the first string is nonempty
    \yystringempty{#2}{\yysecondoftwo}{\yycomparesimplestrings@@{#1}{#2}}%
}

\def\yycomparesimplestrings@@#1#2{% both strings are nonempty
    \yystartsinspace{#1}{%
        \yystartsinspace{#2}{\yyabsorbfirstspace{#1}{#2}}{\yysecondoftwo}%
    }{%
        \yystartsinspace{#2}{\yysecondoftwo}{\yyabsorbfirstnonspace{#1}{#2}}%
    }    
}

\def\yyabsorbfirstspace#1#2{%
    \expandafter\yyabsorbfirstspac@swap\expandafter{\eatonespace#1}{#2}%
}

\def\yyabsorbfirstspac@swap#1#2{%
     \expandafter\yyabsorbfirst@swap\expandafter{\eatonespace#2}{#1}%
}

\def\yyabsorbfirstnonspace#1#2{%
    \expandafter\yyabsorbfirstnonspac@swap\expandafter{\eatone#1}{#2}%
}

\def\yyabsorbfirstnonspac@swap#1#2{%
     \expandafter\yyabsorbfirst@swap\expandafter{\eatone#2}{#1}%
}

\def\yyabsorbfirst@swap#1#2{%
     \yycomparesimplestrings{#2}{#1}%
}

% `compare strings of category code 12' thread ends here

% #1 -- a balanced sequence of tokens
% #2 -- a `parsed version' of the same sequence
%
% #1 should be such that \eatone#1 does not lead to an immediate error

\def\yycomparetailsignatures#1#2{%
    \yypreparsetokensequenc@{\yycomparesimplestrings{#2}}{#1}{}%
}

% #1 -- `call stack'
% #2 -- remaining sequence
% #3 -- remaining parsed sequence
% #4 -- resolved sequence

\def\yyresolvespaces#1#2#3#4{%
    \yystringempty{#2}{#1{#4}}{\yyresolveoneblank#3\end{#2}{#4}{#1}}%
}

\def\yyresolveoneblank#1{%
    \if#1*%
        \expandafter\yyfirstoftwo
    \else
        \expandafter\yysecondoftwo
    \fi
    {\yyresolveonebl@nk}{%
        \ifx#1.%
            \expandafter\yyfirstoftwo
        \else
            \expandafter\yysecondoftwo
        \fi
        {\yyresolveonebl@nk}%
        {\yyconsumebothnonblanks}%
    }%
}

% #1 -- the remainder of the parsed sequence
% #2 -- remaining sequence
% #3 -- resolved sequence

\def\yyresolveonebl@nk#1\end#2#3{%
    \expandafter\yycomparetailsignatures\expandafter{\eatone#2}{#1}%
        {\expandafter\yyresolvespac@sswap\expandafter{\eatone#2}{#1}{#3+}}%
        {\expandafter\yyresolveonebl@nklight\expandafter{\eatone#2}{#1}{#3-}}%
}

% #1 -- remaining sequence
% #2 -- remaining parsed sequence
% #3 -- resolved sequence
% #4 -- `call stack'

\def\yyresolvespac@sswap#1#2#3#4{%
    \yyresolvespaces{#4}{#1}{#2}{#3}%
}

\def\yyconsumebothnonblanks#1\end#2#3{%
    \expandafter\yyconsumebothnonblanksswap\expandafter{\eatone#2}{#1}{#30}%
}

\def\yyconsumebothnonblanksswap#1#2#3#4{%
    \yyresolvespaces{#4}{#1}{#2}{#3}%
}

% #1 -- remaining sequence
% #2 -- the remainder of the parsed sequence
% #3 -- resolved sequence

\def\yyresolveonebl@nklight#1#2#3{%
    \yyresolveonebl@nklighttest#2\end{#1}{#3}%
}

\def\yyresolveonebl@nklighttest#1#2\end#3#4{%
    \yycomparetailsignatures{#3}{#2}%
        {%
            \if#1*%
                \expandafter\yyfirstoftwo
            \else
                \expandafter\yysecondoftwo
            \fi
            {\yyresolvespac@sswap{#3}{#2}{#4+}}%
            {\yyresolvespac@sswap{#3}{#2}{#40}}%
        }%
        {\yyresolveonebl@nklight{#3}{#2}{#4-}}%
}

% `space resolution code' ends here

% #1 -- remaining parsed sequence
% #2 -- analysed sequence

\def\yyanalysetokens@#1#2{%
    \yystringempty{#1}{{#2}}%
        {\yyanalysetok@ns@#1\end{#2}}%
}

\def\yyanalysetok@ns@#1#2\end{%
    \ifx#1.%
        \expandafter\yyfirstoftwo
    \else
        \expandafter\yysecondoftwo
    \fi
    {\yygrabablank{#2}}%
    {%
        \ifx#1[% not a space, an opening brace
            \expandafter\yyfirstoftwo
        \else
            \expandafter\yysecondoftwo
        \fi
        {%
            \yydisableobrace{#2}%
        }{% 
            \ifx#1]% not a space, a closing brace
                \expandafter\yyfirstoftwo
            \else
                \expandafter\yysecondoftwo
            \fi
            {%
                \yydisablecbrace{#2}%
            }{% neither space nor brace
                \yygrabtokenraw{#2}%
            }%
        }%
    }%
}

% #1 -- remaining parsed sequence
% #2 -- analysed sequence
% #3 -- next token

\def\yygrabtokenraw#1#2#3{%
    \expandafter\yyanalysetokens@swap\expandafter{\meaning#3}{#1}{#2}%
}

\def\yyanalysetokens@swap#1#2#3{%
    \yyanalysetokens@{#2}{#3t#1e}%
}

\def\yygrabablank#1#2 {%
    \yyanalysetokens@{#1}{#2s0e}%
}

% #1 -- remaining parsed sequence
% #2 -- analysed sequence

\def\yydisablecbrace#1#2{%
    \yydisablecbrac@{}#1\relax#2\end
}


\def\yydisablecbrac@#1#2{%
    \ifx#2\end
        \yybreak{\yydisablecbrac@@{#1\expandafter\expandafter\expandafter}}%
    \else
        \yybreak{\yydisablecbrac@{#1\expandafter\expandafter\expandafter#2}}%
    \yycontinue
}

\def\yydisablecbrac@@#1{%
    \expandafter\expandafter\expandafter
        \yydisablecbrace@@@#1\end
    \expandafter\expandafter\expandafter
        {\iffalse}\fi\string
}

\def\yydisablecbrace@@@#1\relax#2\end#3{%
    \yystartsinspace{#3}%
        {\expandafter\yyanalysetok@nsswap\expandafter{\eatonespace#3}{#1}{#2c1e}}%
        {\expandafter\yyanalysetok@nsswap\expandafter{\eatone#3}{#1}{#2c2e}}%
}

\def\yyanalysetok@nsswap#1#2#3{%
    \iffalse{\fi\yyanalysetokens@{#2}{#3}#1}%
}

% #1 -- remaining parsed sequence
% #2 -- analysed sequence

\def\yydisableobrace#1#2{%
    \yydisableobrac@{}#1\relax#2\end
}


\def\yydisableobrac@#1#2{%
    \ifx#2\end
        \yybreak{\yydisableobrac@@{#1\expandafter\expandafter\expandafter}}%
    \else
        \yybreak{\yydisableobrac@{#1\expandafter\expandafter\expandafter#2}}%
    \yycontinue
}

\def\yydisableobrac@@#1{%
    \expandafter\expandafter\expandafter
        \yydisableobrace@@@#1\end
    \expandafter\expandafter\expandafter
        {\iffalse}\fi\string
}

\def\yydisableobrace@@@#1\relax#2\end#3{%
    \yystartsinspace{#3}%
        {\expandafter\yyanalysetok@nsswap\expandafter{\eatonespace#3}{#1}{#2o1e}}%
        {\expandafter\yyanalysetok@nsswap\expandafter{\eatone#3}{#1}{#2o2e}}%
}

%    \ifx1\expandafter\eatone\string\11% check if \escapechar is nontrivial

\uccode`\ =`\-

\uppercase{\def\dotspace{ }}

\toksa\expandafter\expandafter\expandafter{\expandafter\meaning\dotspace}

\toksb{-}

\toksc{#2}

\toksd\toksa

\yyreplacestring\toksb\in\toksa\with\toksc

\toksc{}
\yyreplacestring\toksb\in\toksd\with\toksc

\expandafter\def\expandafter\yymatchblankspac@\expandafter#\expandafter1\the\toksd{%
    \yystringempty{#1}{\expandafter\yysecondofthree\expandafter{\string}}%
        {\expandafter\yythirdofthree\expandafter{\string}}%
}

\edef\yymatchblankspace#1{% is it \catcode 10 token?
    \noexpand\iffalse{\noexpand\fi
    \noexpand\expandafter
    \noexpand\yymatchblankspac@
    \noexpand\meaning#1\the\toksd}%
}

% the idea behind the sequence below is that a leading character of category code 10
% is replaced either by a character of category code 10 and charachter code 32 or a character
% of category code 12 and character code other than 32
% note that while it is tempting to replace the definition below by something that ends in
% ... blank space #2{ ... with the hope of absorbing the result of \meaning in one step,
% this will not give the desired result in case of an active character,
% say, `~' that had been \let to the normal blank space

\expandafter\def\expandafter\yynormalizeblankspac@\expandafter#\expandafter1\the\toksd{}

%% test code begins here

\tracingmacros=3
\tracingonline=3

\catcode`\ =13\relax%
\def\actspace{ }%
\catcode`\ =10\relax%

\catcode`\.=13\relax%
\def\actdotspace{.}%
\catcode`\.=12\relax%

\edef\makefunkydotspace{\let\expandafter\noexpand\actdotspace= \dotspace}
\edef\makefunkyspace{\let\expandafter\noexpand\actspace= \space}

\makefunkyspace
\makefunkydotspace

\def\identity#1{#1}

%\def\tempseq{\space\dotspace\space\space\dotspace\expandafter\noexpand\actspace\expandafter\noexpand\actdotspace
%             \end\noexpand\fi\noexpand\else\noexpand\iffalse}
%\def\tempseq{\space\dotspace e}

%\edef\mypars@{%
%    \noexpand\yypreparsetokensequenc@{\noexpand\identity}%
%        {\tempseq}%
%        {}%
%}

%\edef\myparse{\mypars@}

%\toksa\expandafter{\myparse}

%\showthe\toksa

%\edef\myresolve{\noexpand\yyresolvespaces{\errmessage}%
%    {\tempseq}%
%    {\the\toksa}{}
%}

%\show\myresolve

%\myresolve

\catcode`\<=1
\catcode`\>=2
\uccode`\<=32
\uccode`\>=32

\uppercase{\edef\temptest{<> \space\space\dotspace\expandafter\noexpand\actspace\expandafter\noexpand\actdotspace{{} {{}{{ u o l k kk
    \end\noexpand\fi\noexpand\else\noexpand\iffalse{}} }}}}}

%\uppercase{\edef\temptest{\dotspace E <>}}

\show\temptest

\def\displaypreparse#1{%
    \expandafter\errmessage\expandafter{\romannumeral-1\yypreparsetokensequenc@{\yyanalysetokens@}{#1}{}{}#1}%
}

%\def\displaydebraceparse#1{%
%    \yypreparsetokensequenc@{\yydebracesequence{\displayseq}{#1}}{#1}{}%
%}

%\def\displayseq#1{\toksa{#1}\showthe\toksa}

\expandafter\displaypreparse\expandafter{\temptest}

\errmessage{stop!}

%\expandafter\displaydebraceparse\expandafter{\temptest}

\end