include とマージを伴う YAMLベースの configパーサー (試作)

yaml_config.py

# -*- coding: utf-8 -*-
import yaml
import os


def _yaml_constructor_include(loader, node):
    spl = node.value.split(' ')
    if len(spl) == 1:
        file = spl[0]
        keys = None
    else:
        file, key_list = spl
        keys = key_list.split('.')
    file_name = os.path.join(os.path.dirname(loader.name), file)
    with open(file_name) as inputfile:
        o = yaml.load(inputfile)
        if keys:
            for key in keys:
                o = o[key]
            return o
        else:
            return o


class YAMLConfigLoader(yaml.Loader):
    @classmethod
    def initialize_loader(cls):
        cls.add_constructor("!include", _yaml_constructor_include)

YAMLConfigLoader.initialize_loader()


def load_conf_file(file):
    with open(file) as f:
        return yaml.load(f, Loader=YAMLConfigLoader)


def load_conf_files(files):
    d = dict()
    for file in files:
        _merge_dict(d, load_conf_file(file))
    return d


def _merge_dict(to_dic, from_dic):
    for key in from_dic:
        if key in to_dic:
            to_dic[key] = _merge_object(to_dic[key], from_dic[key])
        else:
            to_dic[key] = from_dic[key]
    return to_dic


def _merge_object(to_obj, from_obj):
    if from_obj is None or to_obj is None:
        return from_obj

    if isinstance(to_obj, dict):
        return _merge_dict(to_obj, from_obj)
    else:
        return from_obj