#! /usr/bin/env python # 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 themselfs (if the #if(n)def tests for one of the mentioned# names) are removed as well. # Features: Arbitrary nesting of recognized and unrecognized# preprocesor 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 sysimport 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:            f = open(filename, 'r')            process(f, sys.stdout)            f.close() 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()