beta-0.89.2

[luatex.git] / source / texk / web2c / tiedir / tie.w

% This is TIE.W                            as of 17 Dec 92
%---------------------------------------------------------
% Copyright (c) 1989,1992 by THD/ITI.
% All rights reserved.
%
% This program is distributed WITHOUT ANY WARRANTY, express or implied.
%
% Permission is granted to make and distribute verbatim copies of this
% program provided that the copyright notice and this permission notice
% are preserved on all copies.
%
% Permission is granted to copy and distribute modified versions of this
% program under the conditions for verbatim copying, provided that the
% entire resulting derived work is distributed under the terms of a
% permission notice identical to this one.
%
%
% Version 1.7 was built alike TIE.WEB Version 1.6                  (89-01-27)
%             but used a command line interface only
% Version 2.0 was revised to include optional tab expansion        (89-02-01)
% Version 2.1 deleted WEB relicts. (-js)                           (89-10-25)
% Version 2.2 repaired replacing strategy                          (89-11-27)
% Version 2.3 was slightly modified to be processed with the
%               cweb by Levy&Knuth.
%               also repaired loop control for end of changes test (92-09-24)
% Version 2.4 included <stdlib.h> instead of <malloc.h> when
%               used with ANSI-C                                   (92-12-17)
%

% Here is TeX material that gets inserted after \input cwebmac

\def\hang{\hangindent 3em\indent\ignorespaces}
\font\mc=cmr9
\def\PASCAL{Pascal}
\def\Cl{{\rm C}}
\def\ASCII{{\mc ASCII}}

\def\title{TIE}
\def\topofcontents{\null\vfill
  \centerline{\titlefont The {\ttitlefont TIE} processor}
  \vskip 15pt
  \centerline{(CWEB Version 2.4)}
  \vfill}
\def\botofcontents{
\null\vfill
\item{$\copyright$}1989, 1992
   by Technische Hochschule Darmstadt,\hfill\break
Fachbereich Informatik, Institut f\"ur Theoretische Informatik\hfill\break
All rights reserved.\hfill\break
This program is distributed WITHOUT ANY WARRANTY, express or implied.
\hfill\break
Permission is granted to make and distribute verbatim copies of this
program provided that the copyright notice and this permission notice
are preserved on all copies.
\hfill\break
Permission is granted to copy and distribute modified versions of this
program under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.
}





@* Introduction.

\noindent Whenever a programmer wants to change a given
\.{WEB} or \.{CWEB} program (referred to as a \.{WEB} program throughout
this program) because of system dependencies, she or he will
create a new change file.  In addition there may be a second
change file to modify system independent modules of the
program.  But the \.{WEB} file cannot be tangled and weaved
with more than one change file simultaneously.  Therefore,
we introduce the present program to merge a \.{WEB} file and
several change files producing a new \.{WEB} file.  Since
the input files are tied together, the program is called
\.{TIE}.  Furthermore, the program can be used to merge
several change files giving a new single change file.  This
method seems to be more important because it doesn't modify
the original source file.  The use of \.{TIE} can be
expanded to other programming languages since this processor
only knows about the structure of change files and does not
interpret the master file at all.

The program \.{TIE} has to read lines from several input
files to bring them in some special ordering.  For this
purpose an algorithm is used which looks a little bit
complicated.  But the method used only needs one buffer line
for each input file.  Thus the storage requirement of
\.{TIE} does not depend on the input data.

The program is written in \Cl\ and uses only few features of a
particular environment that may need to be changed in other
installations.
E.g.\ it will not use the |enum| type declarations.
The changes needed may refer to the access of the command line
if this can be not supported by any \Cl\ compiler.

The ``banner line'' defined here should be changed whenever
\.{TIE} is modified.  This program is put into the public
domain.  Nevertheless the copyright notice must not be
replaced or modified.

@d banner  "This is TIE, CWEB Version 2.4."
@d copyright
    "Copyright (c) 1989,1992 by THD/ITI. All rights reserved."


@ The main outline of the program is given in the next section.
This can be used more or less for any \Cl\ program.
@c
@<Global |#include|s@>@;
@<Global constants@>@;
@<Global types@>@;
@<Global variables@>@;
@<Error handling functions@>@;
@<Internal functions@>@;
@<The main function@>@;

@ Here are some macros for common programming idioms.

@d incr(v) v+=1 /* increase a variable by unity */
@d decr(v) v-=1 /* decrease a variable by unity */
@d loop @+ while (1)@+ /* repeat over and over until a |break| happens */
@d do_nothing  /* empty statement */
@f loop while


@ Furthermore we include the additional types |boolean| and |string|.
@d false 0
@d true 1
@<Global types@>=
typedef int boolean;
typedef char* string;


@ The following parameters should be sufficient for most
applications of \.{TIE}.
@^system dependencies@>

@<Global constants@>=
#define buf_size 512 /* maximum length of one input line */
#define max_file_index 9
/* we don't think that anyone needs more than 9 change files,
    but \dots\ just change it */


@ We introduce a history variable that allows us to set a
return code if the operating system can use it.
First we introduce the coded values for the history.
This variable must be initialized.
(We do this even if the value given may be the default for
variables, just to document the need for the initial value.)
@d spotless 0
@d troublesome 1
@d fatal 2

@<Global variables@>=
static int history=spotless;



@* The character set.

\noindent One of the main goals in the design of \.{TIE} has
been to make it readily portable between a wide variety of
computers.  Yet \.{TIE} by its very nature must use a
greater variety of characters than most computer programs
deal with, and character encoding is one of the areas in
which existing machines differ most widely from each other.

To resolve this problem, all input to \.{TIE} is converted to an
internal seven-bit code that is essentially standard \ASCII{}, the
``American Standard Code for Information Interchange.'' The conversion
is done immediately when each character is read in.  Conversely,
characters are converted from \ASCII{} to the user's external
representation just before they are output.  But the algorithm is
prepared for the usage of eight-bit data.

\noindent Here is a table of the standard visible \ASCII{} codes:
$$\def\:{\char\count255\global\advance\count255 by 1}
\count255='40
\vbox{
\hbox{\hbox to 40pt{\it\hfill0\/\hfill}%
\hbox to 40pt{\it\hfill1\/\hfill}%
\hbox to 40pt{\it\hfill2\/\hfill}%
\hbox to 40pt{\it\hfill3\/\hfill}%
\hbox to 40pt{\it\hfill4\/\hfill}%
\hbox to 40pt{\it\hfill5\/\hfill}%
\hbox to 40pt{\it\hfill6\/\hfill}%
\hbox to 40pt{\it\hfill7\/\hfill}}
\vskip 4pt
\hrule
\def\^{\vrule height 10.5pt depth 4.5pt}
\halign{\hbox to 0pt{\hskip -24pt\O{#0}\hfill}&\^
\hbox to 40pt{\tt\hfill#\hfill\^}&
&\hbox to 40pt{\tt\hfill#\hfill\^}\cr
04&\:&\:&\:&\:&\:&\:&\:&\:\cr\noalign{\hrule}
05&\:&\:&\:&\:&\:&\:&\:&\:\cr\noalign{\hrule}
06&\:&\:&\:&\:&\:&\:&\:&\:\cr\noalign{\hrule}
07&\:&\:&\:&\:&\:&\:&\:&\:\cr\noalign{\hrule}
10&\:&\:&\:&\:&\:&\:&\:&\:\cr\noalign{\hrule}
11&\:&\:&\:&\:&\:&\:&\:&\:\cr\noalign{\hrule}
12&\:&\:&\:&\:&\:&\:&\:&\:\cr\noalign{\hrule}
13&\:&\:&\:&\:&\:&\:&\:&\:\cr\noalign{\hrule}
14&\:&\:&\:&\:&\:&\:&\:&\:\cr\noalign{\hrule}
15&\:&\:&\:&\:&\:&\:&\:&\:\cr\noalign{\hrule}
16&\:&\:&\:&\:&\:&\:&\:&\:\cr\noalign{\hrule}
17&\:&\:&\:&\:&\:&\:&\:\cr}
\hrule width 280pt}$$
(Actually, of course, code |040| is an invisible blank space.)  Code |0136|
was once an upward arrow (\.{\char'13}), and code |0137| was
once a left arrow (\.^^X), in olden times when the first draft
of ASCII code was prepared; but \.{TIE} works with today's standard
ASCII in which those codes represent circumflex and underline as shown.
The maximum value used is also defined, it must be changed if an
extended \ASCII{} is used.

If the \Cl\ compiler is not able to process \&{unsigned char}'s, you
should define |ASCII_Code| as \&{short}.
@^system dependencies@>

@<Global types@>=
#define max_ASCII (@'~'+1)
typedef unsigned char ASCII_Code;
         /* eight-bit numbers, a subrange of the integers */


@ \Cl\ was first implemented on a machine that uses the
\ASCII{} representation for characters. But to make it readily
available also for other machines (big brother is watching?)\
we add a conversion that may be undone for most installations.
\.{TIE} assumes that it is being used
with a character set that contains at least the
characters of standard \ASCII{} as listed above.

In order to accommodate this difference, we shall use the
name |text_char| to stand for the data type of the
characters in the input and output files.  We shall also
assume that |text_char| consists of the elements
|first_text_char| through |last_text_char|,
inclusive.  The following definitions should be adjusted if
necessary.
@^system dependencies@>

@d first_text_char 0 /* ordinal number of the smallest element of |text_char|*/
@d last_text_char 255 /* ordinal number of the largest element of |text_char|*/

@<Global types@>=
typedef unsigned char text_char; /* the data type of characters in text files */
typedef FILE* text_file;


@ The \.{TIE} processor converts between \ASCII{} code and
the user's external character set by means of arrays |xord|
and |xchr| that are analogous to \PASCAL's |ord| and |chr|
functions.

The mapping may be disabled by changing the following macro
definitions to just a cast. If your \Cl\ compiler does not support
\&{unsigned char}'s, you should incorporate a binary and with |0xff|.
@^system dependencies@>

@d map_xchr(c)  (text_char)(c)
         /* change this to |xchr[c]| on non \ASCII{} machines */
@d map_xord(c)  (ASCII_Code)(c)
         /* change this to |xord[c]| on non \ASCII{} machines */

@<Global variables@>=
static ASCII_Code xord[last_text_char+1];
         /* specifies conversion of input characters */
static text_char xchr[max_ASCII+1];
         /* specifies conversion of output characters */


@ If we assume that every system using \.{WEB} is able to
read and write the visible characters of standard \ASCII{}
(although not necessarily using the \ASCII{} codes to
represent them), the following assignment statements
initialize most of the |xchr| array properly, without
needing any system-dependent changes.  For example, the
statement |xchr[@'A']='A'| that appears in the present
\.{WEB} file might be encoded in, say, {\mc EBCDIC} code on
the external medium on which it resides, but \.{CTANGLE} will
convert from this external code to \ASCII{} and back again.
Therefore the assignment statement |xchr[65]='A'| will
appear in the corresponding \Cl\ file, and \Cl\ will
compile this statement so that |xchr[65]| receives the
character \.A in the external code.  Note that it
would be quite incorrect to say |xchr[@'A']=@'A'|, because
|@'A'| is a constant of type |int| not \&{char}, and
because we have |@'A'==65| regardless of the external
character set.

@<Set initial values@>=
xchr[@' ']=' ';
xchr[@'!']='!';
xchr[@'\"']='\"';
xchr[@'#']='#';@/
xchr[@'$']='$';
xchr[@'%']='%';
xchr[@'&']='&';
xchr[@'\'']='\'';@/
xchr[@'(']='(';
xchr[@')']=')';
xchr[@'*']='*';
xchr[@'+']='+';@/
xchr[@',']=',';
xchr[@'-']='-';
xchr[@'.']='.';
xchr[@'/']='/';@/
xchr[@'0']='0';
xchr[@'1']='1';
xchr[@'2']='2';
xchr[@'3']='3';@/
xchr[@'4']='4';
xchr[@'5']='5';
xchr[@'6']='6';
xchr[@'7']='7';@/
xchr[@'8']='8';
xchr[@'9']='9';
xchr[@':']=':';
xchr[@';']=';';@/
xchr[@'<']='<';
xchr[@'=']='=';
xchr[@'>']='>';
xchr[@'?']='?';@/
xchr[@'@@']='@@';
xchr[@'A']='A';
xchr[@'B']='B';
xchr[@'C']='C';@/
xchr[@'D']='D';
xchr[@'E']='E';
xchr[@'F']='F';
xchr[@'G']='G';@/
xchr[@'H']='H';
xchr[@'I']='I';
xchr[@'J']='J';
xchr[@'K']='K';@/
xchr[@'L']='L';
xchr[@'M']='M';
xchr[@'N']='N';
xchr[@'O']='O';@/
xchr[@'P']='P';
xchr[@'Q']='Q';
xchr[@'R']='R';
xchr[@'S']='S';@/
xchr[@'T']='T';
xchr[@'U']='U';
xchr[@'V']='V';
xchr[@'W']='W';@/
xchr[@'X']='X';
xchr[@'Y']='Y';
xchr[@'Z']='Z';
xchr[@'[']='[';@/
xchr[@'\\']='\\';
xchr[@']']=']';
xchr[@'^']='^';
xchr[@'_']='_';@/
xchr[@'`']='`';
xchr[@'a']='a';
xchr[@'b']='b';
xchr[@'c']='c';@/
xchr[@'d']='d';
xchr[@'e']='e';
xchr[@'f']='f';
xchr[@'g']='g';@/
xchr[@'h']='h';
xchr[@'i']='i';
xchr[@'j']='j';
xchr[@'k']='k';@/
xchr[@'l']='l';
xchr[@'m']='m';
xchr[@'n']='n';
xchr[@'o']='o';@/
xchr[@'p']='p';
xchr[@'q']='q';
xchr[@'r']='r';
xchr[@'s']='s';@/
xchr[@'t']='t';
xchr[@'u']='u';
xchr[@'v']='v';
xchr[@'w']='w';@/
xchr[@'x']='x';
xchr[@'y']='y';
xchr[@'z']='z';
xchr[@'{']='{';@/
xchr[@'|']='|';
xchr[@'}']='}';
xchr[@'~']='~';@/
xchr[0]=' '; xchr[0x7F]=' '; /* these \ASCII{} codes are not used */


@ Some of the \ASCII{} codes below |0x20| have been given a
symbolic name in \.{TIE} because they are used with a special
meaning.

@d tab_mark   @'\t' /* \ASCII{} code used as tab-skip */
@d nl_mark    @'\n' /* \ASCII{} code used as line end marker */
@d form_feed  @'\f' /* \ASCII{} code used as page eject */


@ When we initialize the |xord| array and the remaining
parts of |xchr|, it will be convenient to make use of an
index variable, |i|.

@<Local variables for initialisation@>=
int i;


@ Here now is the system-dependent part of the character
set.  If \.{TIE} is being implemented on a garden-variety
\Cl\ for which only standard \ASCII{} codes will appear
in the input and output files, you don't need to make any
changes here.
@^system dependencies@>

Changes to the present module will make \.{TIE} more
friendly on computers that have an extended character set,
so that one can type things like \.^^Z.  If you have an
extended set of characters that are easily incorporated into
text files, you can assign codes arbitrarily here, giving an
|xchr| equivalent to whatever characters the users of
\.{TIE} are allowed to have in their input files, provided
that unsuitable characters do not correspond to special
codes like |tab_mark| that are listed above.

@<Set init...@>=
for (i=1;i<@' ';xchr[i++]=' ');
xchr[tab_mark]='\t';
xchr[form_feed]='\f';
xchr[nl_mark]='\n';


@ The following system-independent code makes the |xord|
array contain a suitable inverse to the information in
|xchr|.

@<Set init...@>=
for ( i=first_text_char ; i<=last_text_char ; xord[i++]=@' ' )  do_nothing;
for ( i=1 ; i<=@'~' ; i++ )  xord[xchr[i]] = i;





@* Input and output.

\noindent Output for the user is done by writing on file |term_out|,
which is assumed to consist of characters of type \&{text\_char}.  It
should be linked to |stdout| usually.  Terminal input is not needed in
this version of \.{TIE}.  |stdin| and |stdout| are predefined if we
include the \.{stdio.h} definitions.  Although I/O redirection for
|stdout| is usually available you may lead output to another file if
you change the definition of |term_out|.  Also we define some macros
for terminating an output line and writing strings to the user.

@^system dependencies@>
@d term_out  stdout
@d print(a)  fprintf(term_out,a) /* `|print|' means write on the terminal */
@d print2(a,b)  fprintf(term_out,a,b) /* same with two arguments */
@d print3(a,b,c)  fprintf(term_out,a,b,c) /* same with three arguments */
@d print_c(v)  fputc(v,term_out); /* print a single character */
@d new_line(v)  fputc('\n',v) /* start new line */
@d term_new_line  new_line(term_out)
        /* start new line of the terminal */
@d print_ln(v)  {fprintf(term_out,v);term_new_line;}
        /* `|print|' and then start new line */
@d print2_ln(a,b)  {print2(a,b);term_new_line;} /* same with two arguments */
@d print3_ln(a,b,c)  {print3(a,b,c);term_new_line;}
        /* same with three arguments */
@d print_nl(v)   {term_new_line; print(v);}
        /* print information starting on a new line */
@d print2_nl(a,b)  {term_new_line; print2(a,b);}
        /* same for two arguments */

@<Global |#include|s@>=
#include <stdio.h>


@ And we need dynamic memory allocation.
This should cause no trouble in any \Cl\ program.
@^system dependencies@>

@<Global |#include|s@>=
#ifdef __STDC__
#include <stdlib.h>
#else
#include <malloc.h>
#endif

@ The |update_terminal| function is called when we want to
make sure that everything we have output to the terminal so
far has actually left the computer's internal buffers and
been sent.
@^system dependencies@>

@d update_terminal  fflush(term_out) /* empty the terminal output buffer */





@* Data structures.

\noindent The multiple input files (master file and change
files) are treated the same way.  To organize the
simultaneous usage of several input files, we introduce the
data type \&{in\_file\_modes}.

The mode |search| indicates that \.{TIE} searches for a
match of the input line with any line of an input file in
|reading| mode.  |test| is used whenever a match is found
and it has to be tested if the next input lines do match
also.  |reading| describes that the lines can be read without
any check for matching other lines.  |ignore| denotes
that the file cannot be used.  This may happen because an
error has been detected or because the end of the file has
been found.

\leavevmode |file_types| is used to describe whether a file
is a master file or a change file. The value |unknown| is added
to this type to set an initial mode for the output file.
This enables us to check whether any option was used to select
the kind of output. (this would even be necessary if we
would assume a default action for missing options.)

@<Global types@>=
#define search 0
#define test 1
#define reading 2
#define ignore 3
typedef int in_file_modes; /* should be |enum(search,test,reading,ignore)| */
#define unknown 0
#define master 1
#define chf 2
typedef int file_types; /* should be |enum(unknown,master,chf)| */


@ A variable of type |out_md_type| will tell us in what state the output
change file is during processing. |normal| will be the state, when we
did not yet start a change, |pre| will be set when we write the lines
to be changes and |post| will indicate that the replacement lines are
written.

@<Global types@>=
#define normal 0
#define pre 1
#define post 2
typedef int out_md_type; /* should be |enum(normal,pre,post)| */


@ Two more types will indicate variables used as an index into either
the file buffer or the file table.

@<Global types@>=
typedef int buffer_index; /* |-1..buf_size| */
typedef int file_index;  /* |-1..max_file_index+1| */


@ The following data structure joins all informations needed to use
these input files.
%`line' is a normal identifier throughout this program
@f line dummy   
@<Global types@>=
typedef struct _idsc{
    string name_of_file;
    ASCII_Code buffer[buf_size];
    in_file_modes mode;
    long line;
    file_types type_of_file;
    buffer_index limit;
    text_file the_file;
    } input_description;


@ These data types are used in the global variable section.
They refer to the files in action, the number of change files,
the mode of operation and the current output state.

@<Global variables@>=
static file_index actual_input,test_input,no_ch;
static file_types prod_chf=unknown;
static out_md_type out_mode;


@ All input files (including the master file) are recorded
in the following structure.
Mostly the components are accessed through a local pointer variable.
This corresponds to \PASCAL's \&{with}-statement
and results in a one-time-computation of the index expression.

@<Global variables@>=
static input_description *input_organization[max_file_index+1];





@* File I/O.

\noindent The basic function |get_line| can be used to get a line from
an input file.  The line is stored in the |buffer| part of the
descriptor.  The components |limit| and |line| are updated.  If the
end of the file is reached |mode| is set to |ignore|.  On some systems
it might be useful to replace tab characters by a proper number of
spaces since several editors used to create change files insert tab
characters into a source file not under control of the user.  So it
might be a problem to create a matching change file.
@^tab character expansion@>

We define |get_line| to read a line from a file specified by
the corresponding file descriptor.

@<Internal functions@>=
void get_line(i)
        file_index i;
{register input_description *inp_desc=input_organization[i];
    if (inp_desc->mode==ignore) return;
    if (feof(inp_desc->the_file))
        @<Handle end of file and return@>@;
    @<Get line into buffer@>@;
}


@ End of file is special if this file is the master file.
Then we set the global flag variable |input_has_ended|.

@<Handle end of file ...@>=
{
  inp_desc->mode=ignore;
  inp_desc->limit=-1;  /* mark end-of-file */
  if (inp_desc->type_of_file==master) input_has_ended=true;
  return;
}


@ This variable must be declared for global access.

@<Global variables@>=
static boolean input_has_ended=false;


@ Lines must fit into the buffer completely.
We read all characters sequentially until an end of line is found
(but do not forget to check for |EOF|!).
Too long input lines will be truncated.
This will result in a damaged output if they occur in the
replacement part of a change file, or in an incomplerte check if the
matching part is concerned.
Tab character expansion might be done here.
@^tab character expansion@>

@<Get line into buffer@>=
{int final_limit; /* used to delete trailing spaces */
 int c; /* the actual character read */
 @<Increment the line number and print a progess report at
  certain times@>@;
 inp_desc->limit=final_limit=0;
 while (inp_desc->limit<buf_size) {
   c=fgetc(inp_desc->the_file);
   @<Check |c| for |EOF|, |return| if line was empty, otherwise
        |break| to process last line@>@;
   inp_desc->buffer[inp_desc->limit++]=c=map_xord(c);
   if (c==nl_mark) break; /* end of line found */
   if (c!=@' ' && c!=tab_mark)
      final_limit=inp_desc->limit;
 }
 @<Test for truncated line, skip to end of line@>@;
 inp_desc->limit=final_limit;
}


@ This section does what its name says. Every 100 lines
in the master file we print a dot, every 500 lines the number
of lines is shown.

@<Increment the line number and print ...@>=
incr(inp_desc->line);
if (inp_desc->type_of_file==master && inp_desc->line % 100==0) {
   if (inp_desc->line % 500 == 0)  print2("%ld",inp_desc->line);
   else  print_c('.');
   update_terminal;
}


@ There may be incomplete lines of the editor used does
not make sure that the last character before end of file
is an end of line. In such a case we must process the
final line. Of the current line is empty, we just can \&{return}.
Note that this test must be done {\sl before} the character read
is translated.
@^system dependencies@>

@<Check |c| for |EOF|...@>=
  if (c==EOF) {
    if (inp_desc->limit<=0) {
       inp_desc->mode=ignore;
       inp_desc->limit=-1;  /* mark end-of-file */
       if (inp_desc->type_of_file==master) input_has_ended=true;
       return;
    } else { /* add end of line mark */
        c=nl_mark;
        break;
    }
  }


@ If the line is truncated we must skip the rest
(and still watch for |EOF|!).
@<Test for truncated line, skip to end of line@>=
if (c!=nl_mark) {
   err_print("! Input line too long")(i);
@.Input line too long@>
   while ( (c=fgetc(inp_desc->the_file)) != EOF  &&  map_xord(c) != nl_mark )
      do_nothing; /* skip to end */
   }





@* Reporting errors to the user.

\noindent There may be errors if a line in a given change
file does not match a line in the master file or a
replacement in a previous change file.  Such errors are
reported to the user by saying
$$
   \hbox{|err_print("! Error message")(file_no)|;}
$$
where |file_no| is the number of the file which is concerned by the
error.  Please note that no trailing dot is supplied by the error
message because it is appended by |err_print|.

This function is implemented as a macro.  It gives a message and an
indication of the offending file.  The actions to determine the error
location are provided by a function called |err_loc|.

@d error_loc(m)  err_loc(m); history=troublesome; @+ }
@d err_print(m)  { @+ print_nl(m); error_loc

@<Error handling...@>=
void err_loc(i) /* prints location of error */
        int i;
{
    print3_ln(" (file %s, l.%ld).",
        input_organization[i]->name_of_file,
        input_organization[i]->line);
}


@ Non recoverable errors are handled by calling |fatal_error| that
outputs a message and then calls `|jump_out|'.  |err_print| will print
the error message followed by an indication of where the error was
spotted in the source files.  |fatal_error| cannot state any files
because the problem is usually to access these.

@d fatal_error(m) {
         print(m); print_c('.'); history=fatal;
         term_new_line; jump_out();
         }


@ |jump_out| just cuts across all active procedure levels and jumps
out of the program.  It is used when no recovery from a particular
error has been provided.  The return code from this program should be
regarded by the caller.

@d jump_out() exit(1)





@* Handling multiple change files.

\noindent In the standard version we take the name of the
files from the command line.
It is assumed that filenames can be used as given in the
command line without changes.

First there are some sections to open all files.
If a file is not accessible, the run will be aborted.
Otherwise the name of the open file will be displayed.

@<Prepare the output file@>=
{
    out_file=fopen(out_name,"w");
    if (out_file==NULL) {
         fatal_error("! Could not open/create output file");
@.Could not open/create output file@>
    }
}


@ The name of the file and the file desciptor are stored in
global variables.

@<Global variables@>=
static text_file out_file;
static string out_name;


@ For the master file we start just reading its first line
into the buffer, if we could open it.

@<Get the master file started@>=
{  input_organization[0]->the_file=
          fopen(input_organization[0]->name_of_file,"r");
   if (input_organization[0]->the_file==NULL)
    fatal_error("! Could not open master file");
@.Could not open master file@>
   print2("(%s)",input_organization[0]->name_of_file);
   term_new_line;
   input_organization[0]->type_of_file=master;
   get_line(0);
}

@ For the change files we must skip the comment part and
see, whether we can find any change in it.
This is done by |init_change_file|.

@<Prepare the change files@>=
{file_index i;
  i=1;
  while (i<no_ch) {
    input_organization[i]->the_file=
        fopen(input_organization[i]->name_of_file,"r");
    if (input_organization[i]->the_file==NULL)
        fatal_error("!Could not open change file");
@.Could not open change file@>
    print2("(%s)",input_organization[i]->name_of_file);
    term_new_line;
    init_change_file(i,true);
    incr(i);
  }
}





@*Input/output organization.

\noindent Here's a simple function that checks if two lines
are different.

@<Internal functions@>=
boolean lines_dont_match(i,j)
        file_index i,j;
{
   buffer_index k,lmt;
   if (input_organization[i]->limit != input_organization[j]->limit)
      return(true);
   lmt=input_organization[i]->limit;
   for ( k=0 ; k<lmt ; k++ )
      if (input_organization[i]->buffer[k] != input_organization[j]->buffer[k])
         return(true);
  return(false);
}


@ Function |init_change_file(i,b)| is used to ignore all
lines of the input file with index |i| until the next change
module is found.  The boolean parameter |b| indicates
whether we do not want to see \.{@@x} or \.{@@y} entries during
our skip.

@<Internal functions@>=
void init_change_file(i,b)
        file_index i; boolean b;
{register input_description *inp_desc=input_organization[i];
  @<Skip over comment lines; |return| if end of file@>@;
  @<Skip to the next nonblank line; |return| if end of file@>@;
}


@ While looking for a line that begins with \.{@@x} in the
change file, we allow lines that begin with \.{@@}, as long
as they don't begin with \.{@@y} or \.{@@z} (which would
probably indicate that the change file is fouled up).

@<Skip over comment lines...@>=
loop@+  {ASCII_Code c;
  get_line(i);
  if (inp_desc->mode==ignore) return;
  if (inp_desc->limit<2) continue;
  if (inp_desc->buffer[0] != @'@@') continue;
  c=inp_desc->buffer[1];
  if (c>=@'X'  && c<=@'Z')
    c+=@'z'-@'Z'; /*lowercasify*/
  if (c==@'x') break;
  if (c==@'y' || c==@'z')
    if (b) /* scanning for start of change */
          err_print("! Where is the matching @@x?")(i);
@.Where is the match...@>
}


@ Here we are looking at lines following the \.{@@x}.

@<Skip to the next nonblank line...@>=
do{
  get_line(i);
  if (inp_desc->mode==ignore) {
          err_print("! Change file ended after @@x")(i);
@.Change file ended...@>
          return;
  }
} while (inp_desc->limit<=0);


@ The |put_line| function is used to write a line from
input buffer |j| to the output file.

@<Internal functions@>=
void put_line(j)
        file_index j;
{buffer_index i; /* index into the buffer */
 buffer_index lmt; /* line length */
 ASCII_Code *p; /* output pointer */
  lmt=input_organization[j]->limit;
  p=input_organization[j]->buffer;
  for (i=0;i<lmt;i++) fputc(map_xchr(*p++),out_file);
  new_line(out_file);
}


@ The function |e_of_ch_module| returns true if the input
line from file |i| starts with \.{@@z}.

@<Internal functions@>=
boolean e_of_ch_module(i)
        file_index i;
{register input_description *inp_desc=input_organization[i];
    if (inp_desc->limit<0) {
      print_nl("! At the end of change file missing @@z ");
@.At the end of change file...@>
      print2("%s",input_organization[i]->name_of_file);
      term_new_line;
      return(true);
    } else if (inp_desc->limit>=2)  if (inp_desc->buffer[0]==@'@@' &&
            (inp_desc->buffer[1]==@'Z' || inp_desc->buffer[1]==@'z'))
        return(true);
    return(false);
}


@ The function |e_of_ch_preamble| returns |true| if the input
line from file |i| starts with \.{@@y}.

@<Internal functions@>=
boolean e_of_ch_preamble(i)
        file_index i;
{register input_description *inp_desc=input_organization[i];
    if (inp_desc->limit>=2 && inp_desc->buffer[0]==@'@@')
      if (inp_desc->buffer[1]==@'Y'||inp_desc->buffer[1]==@'y') return(true);
    return(false);
}



@ To process the input file the next section
reads a line of the actual input file and updates the
|input_organization| for all files with index |test_file| greater
|actual_input|.

@<Process a line, |break| when end of source reached@>=
{file_index test_file;
  @<Check the current files for any ends of changes@>@;
  if (input_has_ended && actual_input==0) break; /* all done */
  @<Scan all other files for changes to be done@>@;
  @<Handle output@>@;
  @<Step to next line@>@;
}


@ Any of the current change files may have reached the end of change.
In such a case intermediate lines must be skipped and the next start
of change is to be found. This may make a change file inactive if
it reaches end of file.

@<Check the...@>=
{register input_description *inp_desc;
while (actual_input>0 && e_of_ch_module(actual_input)) {
  inp_desc=input_organization[actual_input];
  if (inp_desc->type_of_file==master) {
        /* emergency exit, everything mixed up!*/
        fatal_error("! This can't happen: change file is master file");
@.This can't happen...@>
  }
  inp_desc->mode=search;
  init_change_file(actual_input,true);
  while ((input_organization[actual_input]->mode!=reading
           && actual_input>0))  decr(actual_input);
}
}


@ Now we will set |test_input| to the file that has another match
for the current line. This depends on the state of the other
change files. If no other file matches, |actual_input| refers to
a line to write and |test_input| ist set to |none|.

@d none  (max_file_index+1)

@<Scan all other files...@>=
test_input=none;
test_file=actual_input;
while (test_input==none && test_file<no_ch-1){
  incr(test_file);
  switch (input_organization[test_file]->mode) {
  case search: if (lines_dont_match(actual_input,test_file)==false) {
              input_organization[test_file]->mode=test;
              test_input=test_file;
               }
              break;
  case test:  if (lines_dont_match(actual_input, test_file)==true) {
                /* error, sections do not match */
                input_organization[test_file]->mode=search;
                err_print("! Sections do not match")(actual_input);
@.Sections do not match@>
                err_loc(test_file);
                init_change_file(test_file,false);
              } else test_input=test_file;
              break;
  case reading: do_nothing; /* this can't happen */
              break;
  case ignore: do_nothing; /* nothing to do */
              break;
  }
}


@ For the output we must distinguish whether we create a new change
file or a new master file.  The change file creation needs some closer
inspection because we may be before a change, in the pattern part or
in the replacement part.  For a master file we have to write the line
from the current actual input.

@<Handle output@>=
if (prod_chf==chf) {
  loop @+ {
    @<Test for normal, |break| when done@>@;
    @<Test for pre, |break| when done@>@;
    @<Test for post, |break| when done@>@;
  }
} else
if (test_input==none) put_line(actual_input);


@ Check whether we have to start a change file entry.
Without a match nothing must be done.

@<Test for normal...@>=
if (out_mode==normal) {
    if (test_input!=none) {
        fputc(map_xchr(@'@@'),out_file); fputc(map_xchr(@'x'),out_file);
        new_line(out_file);
        out_mode=pre;
    } else break;
}


@ Check whether we have to start the replacement text.
This is the case when we have no more matching line.
Otherwise the master file source line must be copied to the
change file.
@<Test for pre...@>=

  if (out_mode==pre) {
    if (test_input==none) {
      fputc(map_xchr(@'@@'),out_file); fputc(map_xchr(@'y'),out_file);
      new_line(out_file);
      out_mode=post;
    } else {
      if (input_organization[actual_input]->type_of_file==master)
        put_line(actual_input);
      break;
    }
  }


@ Check whether an entry from a change file is complete.
If the current change was a change for a change file in effect,
then this change file line must be written.
If the actual input has been reset to the master file we
can finish this change.

@<Test for post...@>=
  if (out_mode==post) {
    if (input_organization[actual_input]->type_of_file==chf) {
        if (test_input==none)  put_line(actual_input);
        break;
    } else {
        fputc(map_xchr(@'@@'),out_file); fputc(map_xchr(@'z'),out_file);
        new_line(out_file);
        new_line(out_file);
        out_mode=normal;
    }
  }


@ If we had a change, we must proceed in the actual file
to be changed and in the change file in effect.

@<Step to next line@>=
get_line(actual_input);
if (test_input!=none) {
  get_line(test_input);
  if (e_of_ch_preamble(test_input)==true) {
    get_line(test_input); /* update current changing file */
    input_organization[test_input]->mode=reading;
    actual_input=test_input;
    test_input=none;
  }
}


@ To create the new output file we have to scan the whole
master file and all changes in effect when it ends.
At the very end it is wise to check for all changes
to have completed--in case the last line of the master file
was to be changed.

@<Process the input@>=
actual_input=0;
input_has_ended=false;
while (input_has_ended==false||actual_input!=0)
   @<Process a line...@>@;
if (out_mode==post) { /* last line has been changed */
   fputc(map_xchr(@'@@'),out_file); fputc(map_xchr(@'z'),out_file);
   new_line(out_file);
   }


@ At the end of the program, we will tell the user if the
change file had a line that didn't match any relevant line
in the master file or any of the change files.

@<Check that all changes have been read@>=
{file_index i;
for (i=1;i<no_ch;i++) {/* all change files */
   if (input_organization[i]->mode!=ignore)
      err_print("! Change file entry did not match")(i);
@.Change file entry ...@>
   }
}


@ We want to tell the user about our command line options.  This is
done by the |usage()| function.  It contains merely the necessary
print statement and exits afterwards.

@<Intern...@>=
void usage()
{
   print("Usage: tie -[mc] outfile master changefile(s)");
   term_new_line;
   jump_out();
}


@ We must scan through the list of parameters, given in |argv|.  The
number is in |argc|.  We must pay attention to the flag parameter.  We
need at least 5~parameters and can handle up to |max_file_index|
change files.  The names fo the file parameters will be inserted into
the structure of |input_organization|.  The first file is special.  It
indicates the output file.  When we allow flags at any position, we
must find out which name is for what purpose.  The master file is
already part of the |input_organization| structure (index~0).  As long
as the number of files found (counted in |no_ch|) is |-1| we have not
yet found the output file name.

@<Scan the parameters@>=
{int act_arg;
    if ( argc < 5  ||  argc > max_file_index+4-1 )  usage();
    no_ch = -1; /* fill this part of |input_organization| */
    for ( act_arg=1 ; act_arg<argc ; act_arg++ ) {
        if (argv[act_arg][0]=='-') @<Set a flag@>@;
        else @<Get a file name@>@;
    }
    if (no_ch<=0|| prod_chf==unknown)  usage();
}


@ The flag is about to determine the processing mode.
We must make sure that this flag has not been set before.
Further flags might be introduced to avoid/force overwriting of
output files.
Currently we just have to set the processing flag properly.

@<Set a flag@>=
if (prod_chf!=unknown)  usage();
else
   switch (argv[act_arg][1]) {
      case 'c':
      case 'C': prod_chf=chf;  break;
      case 'm':
      case 'M': prod_chf=master;  break;
      default:  usage();
      }


@ We have to distinguish whether this is the very first file name
(known if |no_ch==(-1)|) or if the next element of |input_organization|
must be filled.

@<Get a file name@>=
{   if (no_ch==(-1)) {
        out_name=argv[act_arg];
    } else { register input_description *inp_desc;
        inp_desc=(input_description *)
                malloc(sizeof(input_description));
        if (inp_desc==NULL)
                fatal_error("! No memory for descriptor");
@.No memory for descriptor@>
        inp_desc->mode=search;
        inp_desc->line=0;
        inp_desc->type_of_file=chf;
        inp_desc->limit=0;
        inp_desc->name_of_file=argv[act_arg];
        input_organization[no_ch]=inp_desc;
    }
    incr(no_ch);
}


@* The main program.

\noindent Here is where \.{TIE} starts, and where it ends.

@<The main function@>=
main(argc,argv)
        int argc; string *argv;
{{@<Local variables for initialisation@>@;
  @<Set initial...@>@;
 }
  print_ln(banner); /* print a ``banner line'' */
  print_ln(copyright); /* include the copyright notice */
  actual_input=0;
  out_mode=normal;
  @<Scan the parameters@>@;
  @<Prepare the output file@>@;
  @<Get the master file started@>@;
  @<Prepare the change files@>@;
  @<Process the input@>@;
  @<Check that all changes have been read@>@;
  @<Print the job |history|@>@;
}

@ We want to pass the |history| value to the operating system so that
it can be used to govern whether or not other programs are started.
Additionaly we report the history to the user, although this may not
be ``{\mc UNIX}'' style---but we are in best companion: \.{WEB} and
\TeX{} do the same.
@^system dependencies@>

@<Print the job |history|@>=
{string msg;
   switch (history) {
      case spotless: msg="No errors were found"; break;
      case troublesome: msg="Pardon me, but I think I spotted something wrong.";
                break;
      case fatal: msg="That was a fatal error, my friend";  break;
      } /* there are no other cases */
   print2_nl("(%s.)",msg);  term_new_line;
   exit ( history == spotless  ?  0 : 1 );
}





@* System-dependent changes.

\noindent This section should be replaced, if necessary, by
changes to the program that are necessary to make \.{TIE}
work at a particular installation.  It is usually best to
design your change file so that all changes to previous
modules preserve the module numbering; then everybody's
version will be consistent with the printed program.  More
extensive changes, which introduce new modules, can be
inserted here; then only the index itself will get a new
module number.
@^system dependencies@>





@* Index.

\noindent Here is the cross-reference table for the \.{TIE}
processor.