# SPDX-License-Identifier: AGPL-3.0-or-later
"""Configuration class :py:class:`Config` with deep-update, schema validation
and deprecated names.
The :py:class:`Config` class implements a configuration that is based on
structured dictionaries. The configuration schema is defined in a dictionary
structure and the configuration data is given in a dictionary structure.
"""
from __future__ import annotations
from typing import Any
import copy
import typing
import logging
import pathlib
import pytomlpp as toml
__all__ = ['Config', 'UNSET', 'SchemaIssue']
log = logging.getLogger(__name__)
class FALSE:
"""Class of ``False`` singelton"""
# pylint: disable=multiple-statements
def __init__(self, msg):
self.msg = msg
def __bool__(self):
return False
def __str__(self):
return self.msg
__repr__ = __str__
UNSET = FALSE('<UNSET>')
[docs]
class SchemaIssue(ValueError):
"""Exception to store and/or raise a message from a schema issue."""
def __init__(self, level: typing.Literal['warn', 'invalid'], msg: str):
self.level = level
super().__init__(msg)
def __str__(self):
return f"[cfg schema {self.level}] {self.args[0]}"
[docs]
class Config:
"""Base class used for configuration"""
UNSET = UNSET
@classmethod
def from_toml(cls, schema_file: pathlib.Path, cfg_file: pathlib.Path, deprecated: dict) -> Config:
# init schema
log.debug("load schema file: %s", schema_file)
cfg = cls(cfg_schema=toml.load(schema_file), deprecated=deprecated)
if not cfg_file.exists():
log.warning("missing config file: %s", cfg_file)
return cfg
# load configuration
log.debug("load config file: %s", cfg_file)
try:
upd_cfg = toml.load(cfg_file)
except toml.DecodeError as exc:
msg = str(exc).replace('\t', '').replace('\n', ' ')
log.error("%s: %s", cfg_file, msg)
raise
is_valid, issue_list = cfg.validate(upd_cfg)
for msg in issue_list:
log.error(str(msg))
if not is_valid:
raise TypeError(f"schema of {cfg_file} is invalid!")
cfg.update(upd_cfg)
return cfg
def __init__(self, cfg_schema: typing.Dict, deprecated: typing.Dict[str, str]):
"""Construtor of class Config.
:param cfg_schema: Schema of the configuration
:param deprecated: dictionary that maps deprecated configuration names to a messages
These values are needed for validation, see :py:obj:`validate`.
"""
self.cfg_schema = cfg_schema
self.deprecated = deprecated
self.cfg = copy.deepcopy(cfg_schema)
def __getitem__(self, key: str) -> Any:
return self.get(key)
[docs]
def validate(self, cfg: dict):
"""Validation of dictionary ``cfg`` on :py:obj:`Config.SCHEMA`.
Validation is done by :py:obj:`validate`."""
return validate(self.cfg_schema, cfg, self.deprecated)
[docs]
def update(self, upd_cfg: dict):
"""Update this configuration by ``upd_cfg``."""
dict_deepupdate(self.cfg, upd_cfg)
[docs]
def default(self, name: str):
"""Returns default value of field ``name`` in ``self.cfg_schema``."""
return value(name, self.cfg_schema)
[docs]
def get(self, name: str, default: Any = UNSET, replace: bool = True) -> Any:
"""Returns the value to which ``name`` points in the configuration.
If there is no such ``name`` in the config and the ``default`` is
:py:obj:`UNSET`, a :py:obj:`KeyError` is raised.
"""
parent = self._get_parent_dict(name)
val = parent.get(name.split('.')[-1], UNSET)
if val is UNSET:
if default is UNSET:
raise KeyError(name)
val = default
if replace and isinstance(val, str):
val = val % self
return val
[docs]
def set(self, name: str, val):
"""Set the value to which ``name`` points in the configuration.
If there is no such ``name`` in the config, a :py:obj:`KeyError` is
raised.
"""
parent = self._get_parent_dict(name)
parent[name.split('.')[-1]] = val
def _get_parent_dict(self, name):
parent_name = '.'.join(name.split('.')[:-1])
if parent_name:
parent = value(parent_name, self.cfg)
else:
parent = self.cfg
if (parent is UNSET) or (not isinstance(parent, dict)):
raise KeyError(parent_name)
return parent
[docs]
def path(self, name: str, default=UNSET):
"""Get a :py:class:`pathlib.Path` object from a config string."""
val = self.get(name, default)
if val is UNSET:
if default is UNSET:
raise KeyError(name)
return default
return pathlib.Path(str(val))
[docs]
def pyobj(self, name, default=UNSET):
"""Get python object refered by full qualiffied name (FQN) in the config
string."""
fqn = self.get(name, default)
if fqn is UNSET:
if default is UNSET:
raise KeyError(name)
return default
(modulename, name) = str(fqn).rsplit('.', 1)
m = __import__(modulename, {}, {}, [name], 0)
return getattr(m, name)
# working with dictionaries
def value(name: str, data_dict: dict):
"""Returns the value to which ``name`` points in the ``dat_dict``.
.. code: python
>>> data_dict = {
"foo": {"bar": 1 },
"bar": {"foo": 2 },
"foobar": [1, 2, 3],
}
>>> value('foobar', data_dict)
[1, 2, 3]
>>> value('foo.bar', data_dict)
1
>>> value('foo.bar.xxx', data_dict)
<UNSET>
"""
ret_val = data_dict
for part in name.split('.'):
if isinstance(ret_val, dict):
ret_val = ret_val.get(part, UNSET)
if ret_val is UNSET:
break
return ret_val
def validate(
schema_dict: typing.Dict, data_dict: typing.Dict, deprecated: typing.Dict[str, str]
) -> typing.Tuple[bool, list]:
"""Deep validation of dictionary in ``data_dict`` against dictionary in
``schema_dict``. Argument deprecated is a dictionary that maps deprecated
configuration names to a messages::
deprecated = {
"foo.bar" : "config 'foo.bar' is deprecated, use 'bar.foo'",
"..." : "..."
}
The function returns a python tuple ``(is_valid, issue_list)``:
``is_valid``:
A bool value indicating ``data_dict`` is valid or not.
``issue_list``:
A list of messages (:py:obj:`SchemaIssue`) from the validation::
[schema warn] data_dict: deprecated 'fontlib.foo': <DEPRECATED['foo.bar']>
[schema invalid] data_dict: key unknown 'fontlib.foo'
[schema invalid] data_dict: type mismatch 'fontlib.foo': expected ..., is ...
If ``schema_dict`` or ``data_dict`` is not a dictionary type a
:py:obj:`SchemaIssue` is raised.
"""
names = []
is_valid = True
issue_list = []
if not isinstance(schema_dict, dict):
raise SchemaIssue('invalid', "schema_dict is not a dict type")
if not isinstance(data_dict, dict):
raise SchemaIssue('invalid', f"data_dict issue{'.'.join(names)} is not a dict type")
is_valid, issue_list = _validate(names, issue_list, schema_dict, data_dict, deprecated)
return is_valid, issue_list
def _validate(
names: typing.List,
issue_list: typing.List,
schema_dict: typing.Dict,
data_dict: typing.Dict,
deprecated: typing.Dict[str, str],
) -> typing.Tuple[bool, typing.List]:
is_valid = True
for key, data_value in data_dict.items():
names.append(key)
name = '.'.join(names)
deprecated_msg = deprecated.get(name)
# print("XXX %s: key %s // data_value: %s" % (name, key, data_value))
if deprecated_msg:
issue_list.append(SchemaIssue('warn', f"data_dict '{name}': deprecated - {deprecated_msg}"))
schema_value = value(name, schema_dict)
# print("YYY %s: key %s // schema_value: %s" % (name, key, schema_value))
if schema_value is UNSET:
if not deprecated_msg:
issue_list.append(SchemaIssue('invalid', f"data_dict '{name}': key unknown in schema_dict"))
is_valid = False
elif type(schema_value) != type(data_value): # pylint: disable=unidiomatic-typecheck
issue_list.append(
SchemaIssue(
'invalid',
(f"data_dict: type mismatch '{name}':" f" expected {type(schema_value)}, is: {type(data_value)}"),
)
)
is_valid = False
elif isinstance(data_value, dict):
_valid, _ = _validate(names, issue_list, schema_dict, data_value, deprecated)
is_valid = is_valid and _valid
names.pop()
return is_valid, issue_list
def dict_deepupdate(base_dict: dict, upd_dict: dict, names=None):
"""Deep-update of dictionary in ``base_dict`` by dictionary in ``upd_dict``.
For each ``upd_key`` & ``upd_val`` pair in ``upd_dict``:
0. If types of ``base_dict[upd_key]`` and ``upd_val`` do not match raise a
:py:obj:`TypeError`.
1. If ``base_dict[upd_key]`` is a dict: recursively deep-update it by ``upd_val``.
2. If ``base_dict[upd_key]`` not exist: set ``base_dict[upd_key]`` from a
(deep-) copy of ``upd_val``.
3. If ``upd_val`` is a list, extend list in ``base_dict[upd_key]`` by the
list in ``upd_val``.
4. If ``upd_val`` is a set, update set in ``base_dict[upd_key]`` by set in
``upd_val``.
"""
# pylint: disable=too-many-branches
if not isinstance(base_dict, dict):
raise TypeError("argument 'base_dict' is not a ditionary type")
if not isinstance(upd_dict, dict):
raise TypeError("argument 'upd_dict' is not a ditionary type")
if names is None:
names = []
for upd_key, upd_val in upd_dict.items():
# For each upd_key & upd_val pair in upd_dict:
if isinstance(upd_val, dict):
if upd_key in base_dict:
# if base_dict[upd_key] exists, recursively deep-update it
if not isinstance(base_dict[upd_key], dict):
raise TypeError(f"type mismatch {'.'.join(names)}: is not a dict type in base_dict")
dict_deepupdate(
base_dict[upd_key],
upd_val,
names
+ [
upd_key,
],
)
else:
# if base_dict[upd_key] not exist, set base_dict[upd_key] from deepcopy of upd_val
base_dict[upd_key] = copy.deepcopy(upd_val)
elif isinstance(upd_val, list):
if upd_key in base_dict:
# if base_dict[upd_key] exists, base_dict[up_key] is extended by
# the list from upd_val
if not isinstance(base_dict[upd_key], list):
raise TypeError(f"type mismatch {'.'.join(names)}: is not a list type in base_dict")
base_dict[upd_key].extend(upd_val)
else:
# if base_dict[upd_key] doesn't exists, set base_dict[key] from a deepcopy of the
# list in upd_val.
base_dict[upd_key] = copy.deepcopy(upd_val)
elif isinstance(upd_val, set):
if upd_key in base_dict:
# if base_dict[upd_key] exists, base_dict[up_key] is updated by the set in upd_val
if not isinstance(base_dict[upd_key], set):
raise TypeError(f"type mismatch {'.'.join(names)}: is not a set type in base_dict")
base_dict[upd_key].update(upd_val.copy())
else:
# if base_dict[upd_key] doesn't exists, set base_dict[upd_key] from a copy of the
# set in upd_val
base_dict[upd_key] = upd_val.copy()
else:
# for any other type of upd_val replace or add base_dict[upd_key] by a copy
# of upd_val
base_dict[upd_key] = copy.copy(upd_val)
