\input TrIOsupport.tex
%
% First, macros for \input
%
\def\TrIOempty{}\def\TrIOfixedef{\TRIOnoexpand\TrIOempty{}\TRIOendgroup}
% use \let\threenosubdirs=y or \let\twonosubdirs=y before \input \TrIOmacros
\ifx y\threenosubdirs % set the prefix for \input; the directories must no exist
   \def\TrIOnosubdir{nosubdir/nosubdir/nosubdir/}
\else\ifx y\twonosubdirs
   \def\TrIOnosubdir{nosubdir/nosubdir/}
\else
   \def\TrIOnosubdir{nosubdir/}
\fi\fi
\let\threenosubdirs=\undefined \let\twonosubdirs=\undefined
% the next \def gives us the skip value 42 for \csname and \global, \long, \outer
\def\TrIOinputmessage{% inform user what happens and what has to be done
   \TrIOmessage{TrIO >>> ( \TrIOcnt) Line \TRIOthe\TRIOinputlineno: input}%
   \TrIOmessage{>>> enter shown file name without `\TrIOnosubdir'.}\TrIOmessage{<<<}}
\def\input{% add an unknown subdirectory to raise an error
   \TRIObegingroup \TRIOafterassignment\TRIOnoexpand\TrIOempty
   % the next line catches an \edef; then enter: 36, I\TrIOfixedef
   \TRIOdef\TrIOskipXXXVIinsTrIOfixedef\TrIOempty{}\TrIOempty\TrIOhandleglobaldefs
   \TRIOglobal\TRIOlet\TrIOskipXXXVIinsTrIOfixedef= \TRIOundefined \TrIOcountiocmd
   \TrIOmessage{<<<}\TrIOsetcatcodes \TRIOinput TrIOinput.tex
   \TrIOinputmessage \TrIOendgroup \TRIOinput \TrIOnosubdir}% plus file name gives error
\def\TrIOcCkPxXmove#1\input{% transfer tokens closer to \TRIOinput
   \def\TrIOcCkPxXtransfer{#1}\TrIOcCkPxXinput}
\def\TrIOcCkPxXinputmessage{% inform user what happens and what has to be done
   \TrIOmessage{TrIO >>> ( \TrIOcnt) Line \TRIOthe\TRIOinputlineno: INPUT}%
   \TrIOmessage{>>> enter shown file name without `\TrIOnosubdir'.}\TrIOmessage{<<<}}
\def\TrIOcCkPxXinput{% variant of \input for \TrIOcCkPxXmove
   \TRIObegingroup \TRIOafterassignment\TRIOnoexpand\TrIOempty
   \TRIOdef\TrIOskipXXXVIinsTrIOfixedef\TrIOempty{}\TrIOempty\TrIOhandleglobaldefs
   \TRIOglobal\TRIOlet\TrIOskipXXXVIinsTrIOfixedef= \TRIOundefined \TrIOcountiocmd
   \TrIOmessage{<<<}\TrIOsetcatcodes \TRIOinput TrIOinput.tex
   \TrIOcCkPxXinputmessage \TrIOendgroup \TrIOcCkPxXtransfer\TRIOinput \TrIOnosubdir}
%
% Second, macros for \openin
%
\def\openin{\TRIOthe\TrIOtropenin} \TrIOtropenin={\TrIOopenin}
\def\TrIOopenin{\TRIObegingroup \TrIOhandleglobaldefs \TrIOcountiocmd
   \TRIOafterassignment\TrIOOpenIn \TrIOcount=}% get the stream number
\def\TrIOOpenIn{\TRIOafterassignment\TrIOOPENIN
   \TRIOlet\TrIOnxt=}% remove an optional =
\def\TrIOOPENIN{% prepend the file name with a nonexistent subdirectory
   \TrIOmessage{<<<}%
   \TrIOmessage{TrIO >>> ( \TrIOcnt) Line \TRIOthe\TRIOinputlineno:
      openin \TRIOthe\TrIOcount}%
   \TrIOmessage{>>> If you accept that the file (without \TrIOnosubdir) is read}%
   \TrIOmessage{>>> enter `openin' and follow the instructions.}%
   \TrIOmessage{<<<}%
   \TRIOifx=\TrIOnxt \TRIOdef\TrIOnxt{}\TRIOfi % keep a \next<>`='
   \TrIOsetcatcodes \TRIOinput \TrIOnosubdir\TrIOnxt}% read a file name
% look at file ``openin.tex''
\def\TrIOaAmNzZopenin{% get a file name from user for \openin
   \TRIOread16 to \FilenameOPENIN
   \TRIOaAmNzZopenin\TRIOnumber\TrIOcount=\FilenameOPENIN
   \TRIOlet\FilenameOPENIN=\TRIOundefined
   \TRIOlet\TrIOnext=\TRIOundefined \TRIOlet\TrIOnxt=\TRIOundefined \TrIOendgroup}
%
% Third, macros for \immediate and \openout
%
\def\immediate{\TRIOthe\TrIOtrimmediate} \TrIOtrimmediate={\TrIOImmediate}
\def\TrIOImmediate{% set a flag if \openout follows
   \TRIObegingroup \TrIOhandleglobaldefs
   \TRIOafterassignment\TrIOIMMEDIATE
   \TrIOcount=`x}% a trick to expand the following token
\def\TrIOIMMEDIATE#1{% if #1 is \TRIOimmediate set \TrIOimootrue
   \TRIOifx#1\TRIOimmediate \TRIOglobal\TrIOimootrue
   \TRIOelse \TRIOglobal\TrIOimoofalse\TRIOfi
   \TrIOendgroup\TRIOimmediate#1}% apply the primitive
\def\openout{\TRIOthe\TrIOtropenout} \TrIOtropenout={\TrIOopenout}
\def\TrIOopenout{\TRIOimmediate\TRIObegingroup % unique start, not \begingroup
   \TrIOhandleglobaldefs \TrIOcountiocmd
   \TRIOafterassignment\TrIOOpenOut \TrIOcount=}
\def\TrIOOpenOut{\TRIOafterassignment\TrIOOPENOUT
   \TRIOlet\TrIOnxt=}% remove an optional =
\def\TrIOOPENOUT{% prepend the file name with an unknown (!!) subdirectory
   \TrIOmessage{<<<}%
   \TrIOmessage{TrIO >>> ( \TrIOcnt) Line \TRIOthe\TRIOinputlineno:
      \ifTrIOimoo immediate \TRIOfi openout \TRIOthe\TrIOcount}%
   \TrIOmessage{>>> If you accept that the file (without \TrIOnosubdir) is created}%
   \TrIOmessage{>>> enter `openout' and follow the instructions.}%
   \TrIOmessage{<<<}%
   \TRIOifx=\TrIOnxt \TRIOdef\TrIOnxt{}\TRIOfi % keep a \nxt<>`='
   \TrIOsetcatcodes \TRIOinput \TrIOnosubdir\TrIOnxt}% read a file name
% look at file ``openout.tex''
\def\TrIObBlOyYopenout{% get a file name from user for \openout
   \TRIOread16 to \FilenameOPENOUT
   \ifTrIOimoo \TRIOglobal\TrIOimoofalse
      \TRIOlet\TrIOnext=\TRIOimmediate
   \TRIOelse \TRIOlet\TrIOnext=\TRIOrelax
   \TRIOfi
   \TrIOnext\TRIObBlOyYopenout\TRIOnumber\TrIOcount=\FilenameOPENOUT
   \TRIOlet\FilenameOPENOUT=\TRIOundefined
   \TRIOlet\TrIOnext=\TRIOundefined \TRIOlet\TrIOnxt=\TRIOundefined \TrIOendgroup}
%
% Start
%
\TRIOinput TrIOprivate
\begingroup \newlinechar=`\^^J
\errhelp{File I/O ( \input\openin\openout) is now under TrIO's control.^^JBe
   alerted if a file is loaded without the proper TrIO message^^Jand
   follow always the instruction of this message.^^JMake sure that the
   sequence number is incremented sequentially.}
\ifx y\disablespecial % deactivate \special; write to log file
   \TrIOmessage{<<< TrIO >>> \string\special: disabled, trace in \jobname.log}
\else\ifx n\disablespecial % trace \special
   \TrIOmessage{<<< TrIO >>> \string\special: primitive, trace in \jobname.log}
\else
   \TrIOmessage{<<< TrIO >>> \string\special: primitive}
\fi\fi
\let\disablespecial\undefined
\TrIOmessage{<<< TrIO >>> \string\TrIOnosubdir: \TrIOnosubdir}
\errmessage{TrIO activated. Type h to get instructions}\endgroup