%D \module
%D   [       file=deadstone,
%D        version=2007.07.31,
%D          title=\CONTEXT\ User Module,
%D       subtitle=Dead stone calculator for go,
%D         author=Wolfgang Schuster,
%D          email=schuster.wolfgang@googlemail.com,
%D           date=\currentdate,
%D      copyright=Public Domain]

\writestatus{loading}{Context User Module / Dead stone calculator for go}

\unprotect

%D This is the \TEX\ version of the dead stone calculator for the
%D go module. They are a copy of the original idea of the algorithm
%D to find dead stones with a few modifications the author needed
%D to make them work.

%D \macros{clearboard}
%D
%D The \tex{clearboard} set all fields with a intial value of~0 for
%D the empty fields and a value of~3 for the margins. The command
%D can also be used to clear a board and remove all set values.

\def\clearboard
  {\dorecurse{\numexpr\boardsize+\plustwo\relax}
     {\edef\boardrow{\the\numexpr\recurselevel-\plusone\relax}%
      \dorecurse{\numexpr\boardsize+\plustwo\relax}
        {\edef\boardcolumn{\the\numexpr\recurselevel-\plusone\relax}%
         \presetcurrentstone
           {\ifnum\boardrow=\zerocount
              \plusthree
            \else\ifnum\boardrow=\numexpr\boardsize+\plusone\relax
              \plusthree
            \else\ifnum\boardcolumn=\zerocount
              \plusthree
            \else\ifnum\boardcolumn=\numexpr\boardsize+\plusone\relax
              \plusthree
            \else
              \zerocount
            \fi\fi\fi\fi}}}}

\let\laststone\plusone

%D \macros{addstone}
%D
%D The \tex{addstone} is the used to place a stone on the board.
%D The three arguments keeps the current row, the column and the
%D stone color. The values for the row and the column have to be
%D a number, the stone color has do be given with the two values
%D \type{B} for black and \type{W} for white.

\def\addstone(#1:#2:#3)%
  {\global\advance\stonecount\plusone
   \ifx#3B
     \global\let\laststone\plusone
   \else\ifx#3W
     \global\let\laststone\plustwo
   \fi\fi
   \setevalue{field:\number#1:\number#2}%
     {\ifx#3B
        \plusone
      \else\ifx#3W
        \plustwo
      \fi\fi:\number\stonecount}}

\def\blackstone
  {\let\stone \plusone
   \let\enemy \plustwo
   \let\wall  \plusthree
   \let\marked\plusfour
   \let\dead  \plusseven}

\def\whitestone
  {\let\stone \plustwo
   \let\enemy \plusone
   \let\wall  \plusthree
   \let\marked\plusfive
   \let\dead  \plusseven}

\def\firstofcurrentstone #1:#2\relax{\number#1}
\def\secondofcurrentstone#1:#2\relax{\number#2}

\def\currentstone
  {\@EA\@EA\@EA\@EA\@EA\@EA\@EA\firstofcurrentstone\getvalue{field:\boardrow:\boardcolumn}\relax}

\def\currentstonenumber
  {\@EA\@EA\@EA\@EA\@EA\@EA\@EA\secondofcurrentstone\getvalue{field:\boardrow:\boardcolumn}\relax}

\def\leftstone
  {\@EA\@EA\@EA\@EA\@EA\@EA\@EA\firstofcurrentstone\getvalue{field:\boardrow:\the\numexpr\boardcolumn-\plusone\relax}\relax}

\def\rightstone
  {\@EA\@EA\@EA\@EA\@EA\@EA\@EA\firstofcurrentstone\getvalue{field:\boardrow:\the\numexpr\boardcolumn+\plusone\relax}\relax}

\def\topstone
  {\@EA\@EA\@EA\@EA\@EA\@EA\@EA\firstofcurrentstone\getvalue{field:\the\numexpr\boardrow-\plusone\relax:\boardcolumn}\relax}

\def\bottomstone
  {\@EA\@EA\@EA\@EA\@EA\@EA\@EA\firstofcurrentstone\getvalue{field:\the\numexpr\boardrow+\plusone\relax:\boardcolumn}\relax}

\newif\iftracingstones

\def\doprocessstones
  {\markstones
   \iftracingstones\placeterminalboard\fi
   \deadstones
   \dorecurse\deadcount\checkstones
   \revertstones}

\def\processtones
  {\ifcase\laststone
   \or\processwhitetones\processblackstones
   \or\processblackstones\processwhitetones
   \fi}

\def\processblackstones
  {\blackstone
   \doprocessstones}

\def\processwhitetones
  {\whitestone
   \doprocessstones}

\def\setstonemark
  {\setcurrentstone{\ifcase\stone\or\plusfour\or\plusfive\else\plussix\fi}}

%D \macros{markstones}
%D
%D The first internal command is \tex{markstones}, it set the stone value
%D to marked if all consitions are true, otherwise the state will remain
%D with the old value and we check the next one.

\def\markbottomstone
  {\ifcase\bottomstone
   \or\setstonemark
   \or\setstonemark
   \or\setstonemark
   \fi}

\def\markrightstone
  {\ifcase\rightstone
   \or\markbottomstone
   \or\markbottomstone
   \or\markbottomstone
   \fi}

\def\marktopstone
  {\ifcase\topstone
   \or\ifnum\stone=\plusone\else\markrightstone\fi
   \or\ifnum\stone=\plustwo\else\markrightstone\fi
   \or\markrightstone
   \or\ifnum\stone=\plusone\relax\markrightstone\fi
   \or\ifnum\stone=\plustwo\relax\markrightstone\fi
   \fi}

\def\markstones
  {\dorecurse\boardsize
     {\edef\boardrow{\recurselevel}%
      \dorecurse\boardsize
        {\edef\boardcolumn{\recurselevel}%
         \ifnum\currentstone=\stone
           \ifcase\leftstone
           \or\ifnum\stone=\plusone\else\marktopstone\fi
           \or\ifnum\stone=\plustwo\else\marktopstone\fi
           \or\marktopstone
           \or\ifnum\stone=\plusone\relax\marktopstone\fi
           \or\ifnum\stone=\plustwo\relax\marktopstone\fi
           \fi
         \fi}}}

%D \macros{deadstones}
%D
%D The \tex{deadstones} macro check the marked stones from the last
%D step for a dead state. We will now state from the right bottom and
%D go to the left top corner.

\def\deadleftstone
  {\ifcase\leftstone
   \or\ifnum\stone=\plusone\else\setdeadstone\fi
   \or\ifnum\stone=\plustwo\else\setdeadstone\fi
   \or\setdeadstone
   \or\setdeadstone
   \or\setdeadstone
   \fi}

\def\deadbottomstone
  {\ifcase\bottomstone
   \or\ifnum\stone=\plusone\else\deadleftstone\fi
   \or\ifnum\stone=\plustwo\else\deadleftstone\fi
   \or\deadleftstone
   \or\resetdeadstone
   \or\resetdeadstone
   \or\resetdeadstone
   \or\deadleftstone
   \fi}

\def\deadstones
  {\dostepwiserecurse\boardsize\plusone\minusone
     {\edef\boardrow{\recurselevel}%
      \dostepwiserecurse\boardsize\plusone\minusone
      {\edef\boardcolumn{\recurselevel}%
       \ifnum\currentstone=\marked
         \ifcase\rightstone
         \or\ifnum\stone=\plusone\else\deadbottomstone\fi
         \or\ifnum\stone=\plustwo\else\deadbottomstone\fi
         \or\deadbottomstone
         \or
         \or
         \or
         \or\deadbottomstone
         \fi
       \fi}}}

%D \macros{revertstones}
%D
%D The \tex{revertstones} is called after all dead stones are and we will
%D make the board ready for the next move. There are still fields with the
%D value marked on the board and we have to make sure they get their normal
%D state with the values for stone and enemy.

\def\revertstones
  {\dorecurse\boardsize
     {\edef\boardrow{\recurselevel}%
      \dorecurse\boardsize
        {\edef\boardcolumn{\recurselevel}%
         \ifcase\currentstone
         \or
         \or
         \or
         \or\resetstone
         \or\resetstone
         \or
         \or\removedeadstone
         \fi}}}

\def\presetcurrentstone#1%
  {\setxvalue{field:\boardrow:\boardcolumn}{\number#1:0}}

\def\setcurrentstone#1%
  {\setxvalue{field:\boardrow:\boardcolumn}{\number#1:\number\currentstonenumber}}

\def\setdeadstone
  {\setcurrentstone{\plusseven}}

\def\resetdeadstone
  {\setcurrentstone{\ifcase\stone\or\plusone\or\plustwo\else\plussix\fi}}

\let\resetstone\resetdeadstone

\def\keepdeadstone
  {\setcurrentstone{\ifcase\stone\or\plusseven\or\plusseven\else\plussix\fi}}

\def\removedeadstone
  {\appendtodeadstonelist
   \setcurrentstone{\zerocount}}

%D \macros{deadblackstones,deadwhitestones}
%D
%D The dead stones we found in one run are saved in two commalists, their names
%D are \tex{deadblacktones} and \tex{deadwhitestones}. They can be used by users
%D to their positions and numbers in their own macros.

\def\appendtodeadstonelist
  {\ifcase\stone
   \or\expanded{\appendtocommalist{{\boardrow:\boardcolumn:\number\stone:\currentstonenumber}}}\deadblackstones
   \or\expanded{\appendtocommalist{{\boardrow:\boardcolumn:\number\stone:\currentstonenumber}}}\deadwhitestones
   \fi}

\def\cleardeadstonelist
  {\let\deadblackstones\empty
   \let\deadwhitestones\empty}

%D \macros{checkstones}
%D
%D As one of the first examples has shown sometimes still living stones
%D get the value dead in the last step and we have to check for such
%D a case. Tests has shown this need to be done at least two times and
%D make sure this can be increased without problems users can change this
%D with the counter \tex{deadcount} but you should also know increasing
%D this counter will result in longer processing time.

\def\checkdeadstones
  {\ifcase\leftstone
   \or\ifnum\stone=\plusone\relax\resetdeadstone\else\checktopdeadstone\fi
   \or\ifnum\stone=\plustwo\relax\resetdeadstone\else\checktopdeadstone\fi
   \or\checktopdeadstone
   \or\resetdeadstone
   \or\resetdeadstone
   \or\resetdeadstone
   \or\checktopdeadstone
   \fi}

\def\checktopdeadstone
  {\ifcase\topstone
   \or\ifnum\stone=\plusone\relax\resetdeadstone\else\checkrightdeadstone\fi
   \or\ifnum\stone=\plustwo\relax\resetdeadstone\else\checkrightdeadstone\fi
   \or\checkrightdeadstone
   \or\resetdeadstone
   \or\resetdeadstone
   \or\resetdeadstone
   \or\checkrightdeadstone
   \fi}

\def\checkrightdeadstone
  {\ifcase\rightstone
   \or\ifnum\stone=\plusone\relax\resetdeadstone\else\checkbottomdeadstone\fi
   \or\ifnum\stone=\plustwo\relax\resetdeadstone\else\checkbottomdeadstone\fi
   \or\checkbottomdeadstone
   \or\resetdeadstone
   \or\resetdeadstone
   \or\resetdeadstone
   \or\checkbottomdeadstone
   \fi}

\def\checkbottomdeadstone
  {\ifcase\bottomstone
   \or\ifnum\stone=\plusone\relax\resetdeadstone\else\keepdeadstone\fi
   \or\ifnum\stone=\plustwo\relax\resetdeadstone\else\keepdeadstone\fi
   \or\keepdeadstone
   \or\resetdeadstone
   \or\resetdeadstone
   \or\resetdeadstone
   \or\keepdeadstone
   \fi}

\def\checkstones
  {\dorecurse\boardsize
     {\edef\boardrow{\recurselevel}%
      \dorecurse\boardsize
        {\edef\boardcolumn{\recurselevel}%
         \ifcase\currentstone
         \or
         \or
         \or
         \or\ifnum\stone=\plusone\relax\resetdeadstone\fi
         \or\ifnum\stone=\plustwo\relax\resetdeadstone\fi
         \or
         \or\checkdeadstones
         \fi}}}

\protect \endinput