DOCUMENT: PROGRAMMER

This is the programmer document for TClass.  Other documents in this
directory:

AI.doc
TClass.doc
Installation.doc
showbytes.doc

                                  Contents

          1.A - What is TClass.brain?
          1.B - How is it structured?

================================================================================

1.A - What is TClass.brain?

TClass.brain (located in S:) contains info on how to recognize different
types of files.

1.B - How is it structured?

Here's an example TClass.brain file:

#TClass.brain
# lines beginning with # are comments, and blank lines are ignored

C source::%ext(c)::
Document::%ext(doc)::
German document::%ext(dok)::
Uuencoded file::%match(0,begin * *)
Executable::0,0,3,-13,0,0,0,0,0,0,0,i,0,0,0,0,0,0,0::
Font::15,0,0::

This is a short example, of course.  Here's the basic synopsis for each
entry:

<filetype name>::<bytelist>::
  or
<filetype name>::%<function(<args>)>::

So for the font entry:

Font::15,0,0::

If a file's 1st byte is 15, 2nd is 0, and 3rd is 0, then it's a font.  The
rest of the 17 bytes are ignored, since they vary.

Also note that instead of numbers, you can have characters.  For instance,
DMS archives begin with the string "DMS!".  So you could do this:

DMS archive::'D','M','S','!'::

Now, sometimes, you may not be able to make TClass learn files.  Files like C
code and text files obviously can't be learned.  So you can make use of
functions to recognize these.  All function arguments are case insensitive.
AND, when a function takes two or more parameters, you MUST NOT put spaces
after or before commas!!  Ex:
%foobar(hi, 2)  is INVALID
%blech(2,start,8) is valid.
As of now, there are these functions:

%ext(extension)
Where extension is the file extension.  Examples:
C source::%ext(c)::
LHA AutoDisplay file::%ext(displayme)

%match(pos,pattern)
Matches for "pattern" beginning at "pos."  Let's say you had some file type
that always had the word "BEGIN" starting at the 3rd byte:
µ¤BEGIN.........
Since the first two bytes always change, it would be good to do this:
weird file::%match(2,BEGIN*)
Note, this starts at position 2.  ALWAYS with these functions, byte counting
starts at 0, then 1, 2, 3, etc.  Also, the pattern match method is UNIX.  ?
is not used, only * is recognized.  (* is the same as #? in AmigaDOS)

These function descriptions could be vague.  If so, feel free to contact me
at shulick@indiana.edu and I'll help.