addifdefs.py

import collections
import re
import sys

ifs = ["#ifndef", "#ifdef", "#if"]


SLASHAST = re.compile(r"/\*.*?\*/", re.DOTALL)
DOUBLESLASH = re.compile(r"//.*?\n")


def main():
    with open(sys.argv[1]) as f:
        stack = collections.deque([])
        for i, line in enumerate(f):
            if line.startswith("#if"):
                for _if in ifs:
                    if line.startswith(_if):
                        tag = line[len(_if) :].strip()
                        tag = re.sub(SLASHAST, "", tag)
                        tag = re.sub(DOUBLESLASH, "", tag)
                        stack.append(tag)
                        break
                else:
                    raise RuntimeError("Unknown if in line %s" % repr(line))
            elif line.rstrip() == "#else":
                print("#else /* %s */" % stack[-1])
                continue
            elif line.startswith("#else"):
                # print("#else /* %s */" % stack[-1])
                if line.lstrip("#else").strip() != "/* %s */" % stack[-1]:
                    sys.stderr.write(
                        "Line %i: Not replacing %s with %s after #else\n"
                        % (i, repr(line.lstrip("#else")), repr(stack[-1]))
                    )
            elif line.startswith("#endif"):
                if not line.lstrip("#endif").strip():
                    print("#endif /* %s */" % stack.pop())
                    continue
                else:
                    tag = stack.pop()
                    if line.lstrip("#endif").strip() != "/* %s */" % tag:
                        sys.stderr.write(
                            "Line %i: Not replacing %s with %s after #endif\n"
                            % (i, repr(line.lstrip("#endif")), repr(tag))
                        )

            print(line, end="")


if __name__ == "__main__":
    main()