Reformat C++ braces without changing indentation?

Question

We would like to make our C++ brace style more consistent. Right now, our code contains a mix of:

if (cond)
{
    // ...    
}
else
{
    // ...
}

...and:

if (cond) {
    // ...
} else {
    // ...
}

We want to use the latter style exclusively.

However, we don't want to change the indentation of our code. I've tried using astyle, bcpp, GNU indent and Uncrustify (and I've looked at the command-line options for GreatCode). Unfortunately, each of these tools insists on reindenting our code, and most of them mangle C++ constructor initializer lists and preprocessor macros pretty badly.

Are there any C++ code beautifiers which can fix braces while leaving indentation alone? It doesn't have to be a pre-existing tool--if you know how to do this using some crazy Perl one-liner, that's also good. Thank you!

Update: Yes, we aware that this will make it hard to read diffs against older code. This is a long-postponed code cleanup, and we've decided that the day-to-day advantages of consistent formatting outweigh any version-control difficulties.

Answer 1

You really should think twice, and probably thrice, before doing this. It will completely destroy your source code control system's revision history at the point of change. You are using a source code control system, aren't you?

Answer 2

The UNIX command Indent (http://en.wikipedia.org/wiki/Indent_(Unix)) (Available for PCs from GNU) has a million options to customize the reformating exactly as you like.

Answer 3

Wouldn't a hand full of simple regexs do the trick? Like (\).?\n.?\{) -> (\) \{) to delete the space between a closing bracket and an opening curly bracket.

Answer 4

Here's a Perl one-liner that should do what you want.

perl -pi.bak -e 'BEGIN { undef $/; } s/\s*?(\s?\/\/.*)?\r?\n\s*{/ {\1/g; s/}(\s?\/\/.*)?\r?\n\s*else\b(.*)/} else\2\1/g;'

It turns this:

int main(int argc, char *argv[])
{
    int something = 0;
    if (something)    // 5-12-2007
    {
        printf("Hi!\n");
    }
    else   // 5-13-2007
    {
        printf("Bye\n");
    }
    return 0;
}

into this:

int main(int argc, char *argv[]) {
    int something = 0;
    if (something) { // 5-12-2007
        printf("Hi!\n");
    } else { // 5-13-2007
        printf("Bye\n");
    }
    return 0;
}

Answer 5

perl -ei '$/=undef;while(<>){s/}\s*?(\s*\/\/^[\r\n]*)?\r?\n\s*else/} else$1/gm;s/(\s*\/\/[^\r\n]*)?\r?\n\s*{/ {$1/gm;print;}' yoursourcefile.cpp

This first mangles } <eol> <whitespace> else to } else, then removes end-of-lines from <eol> <whitespace> {.

To apply this to a source tree, use find and xargs:

find . -name \*.cpp -print0 | xargs -0 perl -ei '$/=undef;while(<>){s/}\s*?(\s*\/\/^[\r\n]*)?\r?\n\s*else/} else$1/gm;s/(\s*\/\/[^\r\n]*)?\r?\n\s*{/ {$1/gm;print;}'

Answer 6

I've tackled problems like this in the past by first running some tool like astyle to do 95% of what we wanted, and then writing a Perl or Python script over the result to finish the remaining 5%. Try it, it's always good practice to know your regular expressions. :)