codekingpro/portable-devtools

1import configparser2import dataclasses3from dataclasses import dataclass4from pathlib import Path5from typing import Callable6from typing import ClassVar7from typing import Optional8from typing import Union9 10from .helpers import make_path11 12 13class ConfigError(BaseException):14    pass15 16 17class MissingConfig(ConfigError):18    pass19 20 21class MissingConfigSection(ConfigError):22    pass23 24 25class MissingConfigItem(ConfigError):26    pass27 28 29class ConfigValueTypeError(ConfigError):30    pass31 32 33class _GetterDispatch:34    def __init__(self, initialdata, default_getter: Callable):35        self.default_getter = default_getter36        self.data = initialdata37 38    def get_fn_for_type(self, type_):39        return self.data.get(type_, self.default_getter)40 41    def get_typed_value(self, type_, name):42        get_fn = self.get_fn_for_type(type_)43        return get_fn(name)44 45 46def _parse_cfg_file(filespec: Union[Path, str]):47    cfg = configparser.ConfigParser()48    try:49        filepath = make_path(filespec, check_exists=True)50    except FileNotFoundError as e:51        raise MissingConfig(f"No config file found at {filespec}") from e52    else:53        with open(filepath, encoding="utf-8") as f:54            cfg.read_file(f)55        return cfg56 57 58def _build_getter(cfg_obj, cfg_section, method, converter=None):59    def caller(option, **kwargs):60        try:61            rv = getattr(cfg_obj, method)(cfg_section, option, **kwargs)62        except configparser.NoSectionError as nse:63            raise MissingConfigSection(64                f"No config section named {cfg_section}"65            ) from nse66        except configparser.NoOptionError as noe:67            raise MissingConfigItem(f"No config item for {option}") from noe68        except ValueError as ve:69            # ConfigParser.getboolean, .getint, .getfloat raise ValueError70            # on bad types71            raise ConfigValueTypeError(72                f"Wrong value type for {option}"73            ) from ve74        else:75            if converter:76                try:77                    rv = converter(rv)78                except Exception as e:79                    raise ConfigValueTypeError(80                        f"Wrong value type for {option}"81                    ) from e82            return rv83 84    return caller85 86 87def _build_getter_dispatch(cfg_obj, cfg_section, converters=None):88    converters = converters or {}89 90    default_getter = _build_getter(cfg_obj, cfg_section, "get")91 92    # support ConfigParser builtins93    getters = {94        int: _build_getter(cfg_obj, cfg_section, "getint"),95        bool: _build_getter(cfg_obj, cfg_section, "getboolean"),96        float: _build_getter(cfg_obj, cfg_section, "getfloat"),97        str: default_getter,98    }99 100    # use ConfigParser.get and convert value101    getters.update(102        {103            type_: _build_getter(104                cfg_obj, cfg_section, "get", converter=converter_fn105            )106            for type_, converter_fn in converters.items()107        }108    )109 110    return _GetterDispatch(getters, default_getter)111 112 113@dataclass114class ReadsCfg:115    section_header: ClassVar[str]116    converters: ClassVar[Optional[dict]] = None117 118    @classmethod119    def from_cfg_file(cls, filespec: Union[Path, str]):120        cfg = _parse_cfg_file(filespec)121        dispatch = _build_getter_dispatch(122            cfg, cls.section_header, converters=cls.converters123        )124        kwargs = {125            field.name: dispatch.get_typed_value(field.type, field.name)126            for field in dataclasses.fields(cls)127        }128        return cls(**kwargs)129