The old code used a shell loop to convert each controlling macro
definition into a command-line argument, reading the macro definitions
file each time. The new code converts the list of controlling macros
into a sed script which can run through the list of macro definitions
in one go.
Add some explanatory comments, since the code is quite meta.
Use {} instead of () for redirecting a group of commands.
Submitted by: Jonathan Nieder <jrnieder@gmail.com>
Main highlights:
(A) The new -B option compresses blank lines around a deleted section
so that blank lines around "paragraphs" of code don't get doubled.
(B) Lenient evaluation of && and || so that #if expressions can be
evaluated even when some of their sub-expressions cannot be.
(C) The evaluator can now handle macros with arguments.
(D) Portability fixes, especially for unifdefall.
Contributions from:
Ben Hutchings at Solarflare Communications (A and B)
Anders H Kaseorg <andersk@mit.edu> (A and C)
Jonathan Nieder <jrnieder@gmail.com> (D)
Obtained from: http://dotat.at/prog/unifdef/
* It now knows about the existence of #elif which would have
caused it to produce incorrect results in some situations.
* It can now process #if and #elif lines according to the
values of symbols that are specified on the command line.
The expression parser is only a simple subset of what C
allows but it should be sufficient for most real-world
code (it can cope with everything it finds in xterm).
* It has an option for printing all of the symbols that might
control #if processing. The unifdefall script uses this
option along with cpp -dM to strip all #ifs from a file.
* It has much larger static limits.
* It handles nested #ifs much more completely.
There have also been many style improvements: KNF; ANSI function
definitions; all global stuff moved to the top of the file; use
stdbool instead of h0h0bool; const-correctness; err(3) instead
of fprintf(stderr, ...); enum instead of #define; commentary.
I used NetBSD's unifdef as the basis of this since it has received
the most attention over the years.
PR: 37454
Reviewed by: markm, dwmalone
Approved by: dwmalone (mentor)
MFC after: 3 weeks
