.ycm_extra_conf.py

import os
import ycm_core

flags = ['-Wall',
         '-Wextra',
         '--std=c++11',
         '--std=c++1y',
         '-x', 'c++',
         '-I', '.',
         '-isystem', '/usr/local/include',
         '-isystem', '/usr/local/include/eigen3',
         '-isystem',
         '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1',
         '-isystem',
         '/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include',
         ]

compilation_database_folder = ''

if os.path.exists(compilation_database_folder):
    database = ycm_core.CompilationDatabase(compilation_database_folder)
else:
    database = None

SOURCE_EXTENSIONS = ['.h', '.hpp', '.cpp']

def DirectoryOfThisScript():
      return os.path.dirname(os.path.abspath(__file__))

def MakeRelativePathsInFlagsAbsolute(flags, working_directory):
    if not working_directory:
        return list(flags)

    new_flags = []
    make_next_absolute = False
    path_flags = ['-isystem', '-I', '-iquote', '--sysroot=']
    for flag in flags:
        new_flag = flag

        if make_next_absolute:
            make_next_absolute = False
            if not flag.startswith('/'):
                new_flag = os.path.join(working_directory, flag)

        for path_flag in path_flags:
            if flag == path_flag:
                make_next_absolute = True
                break

            if flag.startswith(path_flag):
                path = flag[len(path_flag):]
                new_flag = path_flag + os.path.join(working_directory, path)
                break

        if new_flag:
            new_flags.append(new_flag)

    return new_flags

def IsHeaderFile(filename):
    extension = os.path.splitext(filename)[1]
    return extension in ['.h', '.hxx', '.hpp', '.hh']

def GetCompilationInfoForFile( filename ):
    # The compilation_commands.json file generated by CMake does not have entries
    # for header files. So we do our best by asking the db for flags for a
    # corresponding source file, if any. If one exists, the flags for that file
    # should be good enough.
    if IsHeaderFile(filename):
        basename = os.path.splitext(filename)[0]
        for extension in SOURCE_EXTENSIONS:
            replacement_file = basename + extension
            if os.path.exists(replacement_file):
                compilation_info = database.GetCompilationInfoForFile(
                                        replacement_file)
                if compilation_info.compiler_flags_:
                    return compilation_info
        return None
    return database.GetCompilationInfoForFile(filename)

def FlagsForFile(filename, **kwargs):
    if database:
        compilation_info = GetCompilationInfoForFile(filename)
        if not compilation_info:
            return None

        final_flags = MakeRelativePathsInFlagsAbsolute(
                        compilation_info.compiler_flags_,
                        compilation_info.compiler_working_dir_)
    else:
        relative_to = DirectoryOfThisScript()
        final_flags = MakeRelativePathsInFlagsAbsolute(flags, relative_to)

    return {
            'flags': final_flags,
            'do_cache': True
    }