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\ifx\LOOP\relax\endinput\else\let\LOOP=\relax\fi % \input only once
%
% loop.tex: A simple looping construct (meta-macros).
% version: 1.0 release: 26 June 1991
%
% copyright (c) 1991 Marcel R. van der Goot
% You can use these macros to typeset documents. You may
% distribute this file freely, provided that you also distribute
% the accompanying documentation.
% You may make changes to this file, or extract portions
% of it for inclusion in other files, provided that
% (1) you change the name of the file;
% (2) you give proper credit and include copyright
% information where applicable;
% (3) explain how an unchanged version can be obtained; and
% (4) document the usage of your macros/changes (if usage
% of your macros is not worth documenting, they must not
% be worth using).
% You are not allowed to use the name ``Midnight Macros'' for
% any changed files.
% The above rules for making changes do not apply where it
% is explicitly noted in this file that something can be changed
% to conform to your local installation.
%
% USAGE:
% See the file loop.doc
%
% original: csvax.cs.caltech.edu [131.215.131.131] in pub/tex
% (use anonymous ftp). Also in various archives.
%
% Caltech, Pasadena --- Marcel van der Goot
% marcel@cs.caltech.edu
% Caltech 256--80
% Pasadena, CA 91125
% USA
% (818) 356--4603
%
% update history:
% version 1.0: This one.
% release 26 April 1991: This one.
% release 15 April 1991: Did not have \long in \Loop, \_break, and
% \_continue.
% release 8 Feb 1991: Used \next instead of \Lp_next.
%
%%%%%% CODE: (you don't need to read this to use the macros)
{
\catcode`\_=11 % 11 = letter; to make macros private
\globaldefs=1
% Code to supply \fi's:
\def\do_fi{\fi\finish_ifs}
\def\finish_ifs
{\ifnum\count255>0 %
\let\Lp_next=\do_fi
\else\let\Lp_next=\relax
\fi
\advance\count255 by-1 %
\Lp_next
}
% The loop (tail-recursion does not clog memory):
\long\def\Loop#1\Pool%
{\def\Pool{#1\Pool}%
\Pool
}
% \Break could have been defined as
% \def\Break#1#2\Pool{{\count255=#1 \finish_ifs}}
% but this fails if you do
% \ifnum\count0>5\Break
% without space after the 5: \Break wil be expanded to see if there
% are more digits (and expanding \Break means reading its 2nd argument).
% With the solution below, only \Break is expanded because it starts
% with \relax which is not a number. Using \afterassignment rather
% than passing the number as argument gives better error messages.
\def\Break
{\relax\afterassignment\_break
\bgroup\count255=
}
\long\def\_break#1\Pool%
{\finish_ifs
\egroup
}
\def\Continue
{\relax\afterassignment\_continue
\bgroup\count255=
}
\long\def\_continue#1\Pool%
{\finish_ifs
\egroup
\Pool
}
} % restore \catcode`\_, \globaldefs
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