How to indent macros in this manner using a beautifier? - clang

Question

I want my preprocessors to be indented in this manner:
int foo_func()
{
normal_code();
normal_code();
#ifdef FOO
# define aaa
# define bbb
code_that_only_foo();
code_that_only_foo();
#endif
normal_code_again();
normal_code_again();
}
I have tried clang-format, but it removes all spaces after # directive, and I failed to find any option to control that behavior. So, Could clang-format perform preprocessor indentation in that way?

Answer 1

If you cannot find a tool that does the job, write a tool that does:
#!/usr/bin/env python3
from sys import stdin
from string import whitespace
def main():
not_directive = whitespace + '#'
indentation = 0
for line in stdin:
stripped = line.lstrip()
if stripped.startswith('#'):
directive = stripped.lstrip(not_directive)
if directive.startswith('endif'):
indentation -= 1
print('#{}{}'.format(' ' * indentation, directive), end='')
if directive.startswith('if'):
indentation += 1
else:
print(line, end='')
if __name__ == '__main__':
main()
See it working online
It reads the source from the stdin, and writes changed source to the stdout.
You can easily redirect input and output with shell.
If you don't know Python3 and wish to understand it:
string.lstrip(chars) returns string with chars removed from it's beggining.
chars defaults to whitespace.
'test' * 0 => '', 'test' * 1 => 'test', 'test' * 3 => 'testtesttest'
'#{}{}'.format('textA', 'textB') => '#textAtextB'