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% This macro source file is from the four volume series
% "TeX in Practice" by Stephan von Bechtolsheim, published
% 1993 by Springer-Verlag, New York.
% Copyright 1993 Stephan von Bechtolsheim.
% No warranty or liability is assumed.
% This macro may be copied freely if no fees other than
% media cost or shipping charges are charged and as long
% as this copyright and the following source code itself
% is not changed. Please see the series for further information.
%
% Version: 1.0
% Date: May 1, 1993
%
%
% This source code is documented in 27.1.9.1, p. III-417.
% Original source in file "macros7.TEX", starting line 1022.
\wlog{L: "ivpyr.tip" ["macros7.TEX," l. 1022, p. III-417]}%
% This file DOES belong to format "texip."
\InputD{futlet.tip}
\InputD{list-mac.tip}
\InputD{wtolist.tip}
\catcode`\@ = 11
\newdimen\@MaximumCurrentLineWidth
\newdimen\@LineWidthLastLine
\newdimen\@LineWidthMinDiff
\newbox\@IPCurrentLineBox
\newbox\@IPCurrentLineBoxTry
\def\InvertedPyramid #1#2#3{%
    \WordsToTeXList{\IVList}#3\EndWordsToTeXList
    \def\LineLengthList{#1}%
    \@LineWidthLastLine = 0pt
    \@LineWidthMinDiff = #2
    \CarOfList{\IVList}{\@IVListTemp}
    \DropFirstElementOfList{\IVList}
    \setbox\@IPCurrentLineBox = \hbox{\@IVListTemp}%
    \CarOfList{\LineLengthList}{\@IVListTemp}% 
    \@MaximumCurrentLineWidth = \@IVListTemp
    \DropFirstElementOfList{\LineLengthList}%
    \ForEveryListElement{\IVList}{\@IVListTypeset}%
    \ifvoid\@IPCurrentLineBox
        \errmessage{\string\InvertedPyramid:
            empty \string\@IPCurrentLineBox}%
    \else
        \centerline{\box\@IPCurrentLineBox}%
    \fi
}
\def\@IVListTypeset #1{%
    \setbox\@IPCurrentLineBoxTry =
        \hbox{\copy\@IPCurrentLineBox \space#1}%
    \ifdim\wd\@IPCurrentLineBoxTry < \@MaximumCurrentLineWidth
        \setbox\@IPCurrentLineBox = \box\@IPCurrentLineBoxTry
    \else
        \@LineWidthLastLine = \wd\@IPCurrentLineBox
        \centerline{\box\@IPCurrentLineBox}%
        \setbox\@IPCurrentLineBox = \hbox{#1}%
        \CarOfList{\LineLengthList}{\@IVListTemp}% 
        \@MaximumCurrentLineWidth = \@IVListTemp
        \DropFirstElementOfList{\LineLengthList}%
        \dimen0 = \@LineWidthLastLine
        \advance\dimen0 by -\@MaximumCurrentLineWidth
        \ifdim\dimen0 < \@LineWidthMinDiff
            \@MaximumCurrentLineWidth = \@LineWidthLastLine
            \advance\@MaximumCurrentLineWidth by -\@LineWidthMinDiff
        \fi
    \fi
}
\catcode`\@ = 12