% 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 30.8.1, p. III-564.
% Original source in file "pp1.TEX", starting line 1572.
\wlog{L: "part-cr.tip" ["pp1.TEX," l. 1572, p. III-564]}%
% This file DOES belong to format "texip."
\InputD{gobble.tip}
\InputD{pickfs.tip}
\InputD{namedef.tip}
\InputD{defauarg.tip}
\InputD{compst.tip}
\InputD{isprefix.tip}
\InputD{droppre.tip}
\catcode`\@ = 11
\newif\if@LabelsOk
\def\@LabelRefPrefix{@REF-}
\def\@LabelIsDefined #1{%
    TT\fi
    \if\NameDefinedConditional{\@LabelRefPrefix#1}%
}
\def\@NewLabel #1#2#3{% 
    \if\@LabelIsDefined{#1}%
        \wlog{\string\@NewLabel: warning: label "#1"
            already defined.}%
    \fi
    \NameGdef{\@LabelRefPrefix #1}{{#2}{#3}}% 
}
\let\Saved@NewLabel = \@NewLabel
\def\Ref #1{% 
    \@ref{0}{#1}%
    \if\StringsEqualConditional{\@TheExpandedLabel}{??}%
        {??}%
    \else
        \@TheExpandedLabel
    \fi
    \@PrintAfterLabel
}
\def\PageRef #1{% 
    \@ref{1}{#1}%
    \if\StringsEqualConditional{\@TheExpandedLabel}{??}%
        {??}%
    \else
        \@TheExpandedLabel
    \fi
    \@PrintAfterLabel
}
\def\@MostRecentLabel{}
\def\@ref #1#2{%
    \xdef\@PrintAfterLabel{}%
    \DefaultArg{\@ThisLabel}{#2}{\@MostRecentLabel}% 
    \if\StringsEqualConditional{\@ThisLabel}{.}% 
        \xdef\@ThisLabel{\@MostRecentLabel}%
        \xdef\@PrintAfterLabel{.}%
    \fi
    \if\StringsEqualConditional{\@ThisLabel}{,}% 
        \xdef\@ThisLabel{\@MostRecentLabel}%
        \xdef\@PrintAfterLabel{,}%
    \fi
    \if\StringsEqualConditional{\@ThisLabel}{)}% 
        \xdef\@ThisLabel{\@MostRecentLabel}%
        \xdef\@PrintAfterLabel{)}%
    \fi
    \if\StringsEqualConditional{\@ThisLabel}{;}%
        \xdef\@ThisLabel{\@MostRecentLabel}%
        \xdef\@PrintAfterLabel{;}%
    \fi
    \xdef\@MostRecentLabel{\@ThisLabel}% 
    \if\@LabelIsDefined{\@ThisLabel}%
        \edef\@CrefTemp{\NameUse{\@LabelRefPrefix\@ThisLabel}}%
        \ifcase #1\relax 
            \edef\@TheExpandedLabel{%
                \expandafter\PickFirstOfTwo\@CrefTemp}%
        \or
            \edef\@TheExpandedLabel{%
                \expandafter\PickSecondOfTwo\@CrefTemp}%
        \fi
    \else
        \def\@TheExpandedLabel{??}
        \wlog{\string\@ref: Label \@ThisLabel\space undefined.}%
    \fi
}
\catcode`\@ = 12