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#! /usr/bin/env python3
# Selectively preprocess #ifdef / #ifndef statements.
# Usage:
# ifdef [-Dname] ... [-Uname] ... [file] ...
#
# This scans the file(s), looking for #ifdef and #ifndef preprocessor
# commands that test for one of the names mentioned in the -D and -U
# options. On standard output it writes a copy of the input file(s)
# minus those code sections that are suppressed by the selected
# combination of defined/undefined symbols. The #if(n)def/#else/#else
# lines themselves (if the #if(n)def tests for one of the mentioned
# names) are removed as well.
# Features: Arbitrary nesting of recognized and unrecognized
# preprocessor statements works correctly. Unrecognized #if* commands
# are left in place, so it will never remove too much, only too
# little. It does accept whitespace around the '#' character.
# Restrictions: There should be no comments or other symbols on the
# #if(n)def lines. The effect of #define/#undef commands in the input
# file or in included files is not taken into account. Tests using
# #if and the defined() pseudo function are not recognized. The #elif
# command is not recognized. Improperly nesting is not detected.
# Lines that look like preprocessor commands but which are actually
# part of comments or string literals will be mistaken for
# preprocessor commands.
import sys
import getopt
defs = []
undefs = []
def main():
opts, args = getopt.getopt(sys.argv[1:], 'D:U:')
for o, a in opts:
if o == '-D':
defs.append(a)
if o == '-U':
undefs.append(a)
if not args:
args = ['-']
for filename in args:
if filename == '-':
process(sys.stdin, sys.stdout)
else:
with open(filename) as f:
process(f, sys.stdout)
def process(fpi, fpo):
keywords = ('if', 'ifdef', 'ifndef', 'else', 'endif')
ok = 1
stack = []
while 1:
line = fpi.readline()
if not line: break
while line[-2:] == '\\\n':
nextline = fpi.readline()
if not nextline: break
line = line + nextline
tmp = line.strip()
if tmp[:1] != '#':
if ok: fpo.write(line)
continue
tmp = tmp[1:].strip()
words = tmp.split()
keyword = words[0]
if keyword not in keywords:
if ok: fpo.write(line)
continue
if keyword in ('ifdef', 'ifndef') and len(words) == 2:
if keyword == 'ifdef':
ko = 1
else:
ko = 0
word = words[1]
if word in defs:
stack.append((ok, ko, word))
if not ko: ok = 0
elif word in undefs:
stack.append((ok, not ko, word))
if ko: ok = 0
else:
stack.append((ok, -1, word))
if ok: fpo.write(line)
elif keyword == 'if':
stack.append((ok, -1, ''))
if ok: fpo.write(line)
elif keyword == 'else' and stack:
s_ok, s_ko, s_word = stack[-1]
if s_ko < 0:
if ok: fpo.write(line)
else:
s_ko = not s_ko
ok = s_ok
if not s_ko: ok = 0
stack[-1] = s_ok, s_ko, s_word
elif keyword == 'endif' and stack:
s_ok, s_ko, s_word = stack[-1]
if s_ko < 0:
if ok: fpo.write(line)
del stack[-1]
ok = s_ok
else:
sys.stderr.write('Unknown keyword %s\n' % keyword)
if stack:
sys.stderr.write('stack: %s\n' % stack)
if __name__ == '__main__':
main()
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