% $Header: /a/tampa/h/tampa_a/fac/levy/texts/geombook/RCS/geomenv.sty,v 1.7 92/07/17 13:44:21 levy Exp $

\@ifundefined{@@newtheorem}{}{\endinput}

%
% \newtheorem is modified so as to accept a (first) optional argument.
% If this is present, the new theorem type ``foo'' will spawn an inner
% environment ``foo@''.  The optional argument contains two
% brace-delimited token sequences, be inserted before and after the inner
% environment starts.
%
\def\newtheorem{\@ifnextchar[{\@newtheorem}{\@newtheorem[{}{}]}}%]

\long\def\@newtheorem[#1]{\@@newtheorem#1}

\long\def\@@newtheorem#1#2#3{%
  \newenvironment{#3}%
    {\def\object@type{#3}#1\@ifnextchar[{\@enva{#3}{#2}}{\@envb{#3}{#2}}}%]
    {\end{#3@}}%
  \@ifnextchar[{\@othm{#3@}}{\@nnthm{#3}}%]
}

\def\@nnthm#1#2{%
\@ifnextchar[{\@xnnthm{#1}{#2}}{\@ynnthm{#1}{#2}}}
 
\def\@xnnthm#1#2[#3]{\@definecounter{#1}\@addtoreset{#1}{#3}%
\expandafter\xdef\csname the#1\endcsname{\expandafter\noexpand
  \csname the#3\endcsname \@thmcountersep \@thmcounter{#1}}%
\global\@namedef{#1@}{\@thm{#1}{#2}}\global\@namedef{end#1@}{\@endtheorem}}
 
\def\@ynnthm#1#2{\@definecounter{#1}%
\expandafter\xdef\csname the#1\endcsname{\@thmcounter{#1}}%
\global\@namedef{#1@}{\@thm{#1}{#2}}\global\@namedef{end#1@}{\@endtheorem}}

\def\@enva#1#2[#3]{\begin{#1@}[#3]#2}
\def\@envb#1#2{\begin{#1@}#2}

%
% Avoid indentation after end of theorem-like environment.
%

\def\end#1{\csname end#1\endcsname\@checkend{#1}%
  \expandafter\endgroup \if@endpe \@doendpe \@restorepar \fi
  \if@ignore \global\@ignorefalse \ignorespaces\fi}

%
% \theoremintro allows the user to choose how the theorem take is
% going to look like.
%

\def\theoremintro#1{\normalshape\bf#1}

\def\@begintheorem#1#2{\trivlist\item[\hskip\labelsep{\theoremintro{#1\ #2.}}]}

\def\@opargbegintheorem#1#2#3{\trivlist
   \item[\hskip \labelsep{\theoremintro{#1\ #2\ (#3).}}]%
   \ifautolabel\label*{#3}\fi}

%
%  \specialdigits causes digits and punctuation to become active
%  and print in roman type.  \regulardigits cancels that.
%

\def\dowith#1{\let\@tempa#1%
        \@tempa,\@tempa.\@tempa:\@tempa;\@tempa(\@tempa)%
        \@tempa0\@tempa1\@tempa2\@tempa3\@tempa4%
        \@tempa5\@tempa6\@tempa7\@tempa8\@tempa9}
%
\def\makeactive#1{\catcode`#1=13}
\def\makeother#1{\catcode\expandafter`\noexpand#1=12}
\def\makechoice#1{\edef#1{%
  \noexpand\ifmmode\string#1%
  \noexpand\else\noexpand\ifhmode\/\noexpand\fi%
              {\noexpand\normalshape\string#1}\noexpand\fi}}
%
\def\regulardigits{\dowith\makeother}

{\dowith\makeactive
\gdef\specialdigits{%
\dowith\makeactive
\let\@tempa\makechoice
        \@tempa,\@tempa.\@tempa:\@tempa;\@tempa(\@tempa)%
        \@tempa0\@tempa1\@tempa2\@tempa3\@tempa4%
        \@tempa5\@tempa6\@tempa7\@tempa8\@tempa9}%
}

% The proof environment takes an optional argument, which defaults
% to \prooftag (which should be set by theorem-like environments).
% This argument is stored in \provedbox (after being passed to
% \provedboxcontents), to be printed in the ``proved box'' at 
% the end of the proof.  It is also printed at the beginning of proof,
% after being passed to \proofintro.

% If the proof
% ends with a displayed formula, it is recommented that the proved box
% be placed next to the formula (as if it were a tag).  This is done
% by inserting \proved before the closing $$.  In even more difficult
% cases (e.g., if the formula already has a tag, or is part of a 
% multi-line display), plop \box\provedbox where we want the box to be.

\def\prooftag{}
\def\setprooftag{\xdef\prooftag{\@currentlabel}}

\newenvironment{proof}
  {\trivlist\item[]\@ifnextchar[{\pro@f}{\pro@f[\prooftag]}}%]
  {\ifvoid\provedbox\else\hproved\fi\endtrivlist}

\def\pro@f[#1]{\setbox\provedbox\hbox{\provedboxcontents{#1}}\proofintro{#1}}

\def\proofintro#1{\def\@tempa{#1}%
  {\it Proof\ifx\@tempa\empty\else\ of #1\fi. }\ignorespaces}

\def\provedboxcontents#1{\def\@tempa{#1}%
  \ifx\@tempa\empty$\square$\else\fbox{\small#1}\fi}

\newbox\provedbox

\def\proved{\ifmmode\eqno{\box\provedbox}\else\hproved\fi}

\def\hproved{\unskip\nobreak\hfil\penalty50\hskip.5em\hbox{}\nobreak\hfil
  \box\provedbox{\parfillskip=0pt\finalhyphendemerits=0\par}}

% $Log:	geomenv.sty,v $
%Revision 1.7  92/07/17  13:44:21  levy
%*** empty log message ***
%
%Revision 1.6  92/07/13  21:54:27  levy
%further cleaned up the environments
%
%Revision 1.5  92/07/13  11:12:10  levy
%big change (abolished MakeStEnv)
%
%Revision 1.4  92/06/15  19:15:35  levy
%fixed disappearing punctuation in fancy italics
%
%Revision 1.3  92/06/03  11:25:24  levy
%active punctuation
%
%Revision 1.2  92/04/07  09:08:56  levy
%*** empty log message ***
%
%Revision 1.1  1992/03/21  02:42:28  levy
%Initial revision
%