pre-commit

#!/usr/bin/env python3
import functools
import os
from pprint import pprint
import re
import subprocess
import sys

class ValidationError(Exception): pass

def check_output(cmd, expect_process_error=False):
    try:
        return subprocess.check_output(cmd)
    except Exception as e:
        if not expect_process_error or not isinstance(e, subprocess.CalledProcessError):
            print('Exception while running cmd %s' % (cmd,))
        raise

def changes():
    return check_output(('git', 'diff', '--no-ext-diff', '--cached', '-U0'))

def toplevel():
    return check_output(('git', 'rev-parse', '--show-toplevel')).strip(b'\n').decode('utf-8')

def toList(fn):
    return functools.wraps(fn)(lambda *args, **kwargs: list(fn(*args, **kwargs)))

top = toplevel()

clangformat = "/usr/local/clang_3_6_0/bin/clang-format"

### CLANG-FORMAT BEGIN
if os.path.exists(os.path.join(top, '.clang-format')):
    reformatted_files = []
    files_had_unstaged_edits = []
    for filename in check_output(['git', 'diff-index', '--cached', '--name-only', 'HEAD']).decode('utf-8').splitlines():
        if any(filename.endswith(ext) for ext in ('.cpp', '.h', '.hpp')):
            file_path = os.path.join(top, filename)

            with open(file_path, 'rb') as f:
                staged = f.read()
            formatted = check_output([clangformat, file_path])

            if staged == formatted:
                continue

            try:
                check_output(['git', 'diff', '--exit-code', file_path], expect_process_error=True)
            except subprocess.CalledProcessError:
                files_had_unstaged_edits.append(filename)

            check_output([clangformat, '-i', file_path])

            try:
                check_output(['git', 'diff', '--exit-code', file_path], expect_process_error=True)
            except subprocess.CalledProcessError:
                reformatted_files.append(filename)

    if reformatted_files:
        print('These files were reformatted with clang-format, please stage the changes first:\n- %s'
              % '\n- '.join(reformatted_files), file=sys.stderr)
    if files_had_unstaged_edits:
        print('\nThese files had unstaged edits before clang-format reformatting. Please stage desired parts and confirm the commit again.\n- %s'
              % '\n- '.join(files_had_unstaged_edits), file=sys.stderr)
    if reformatted_files or files_had_unstaged_edits:
        exit(1)
### CLANG-FORMAT END

exit(0)