#!/usr/bin/env python3
#
# parser.py
"""
Configuration parser.
"""
#
# Copyright © 2020-2021 Dominic Davis-Foster <dominic@davis-foster.co.uk>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
# DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
# OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
# OR OTHER DEALINGS IN THE SOFTWARE.
#
# stdlib
import tempfile
from typing import Any, List, Mapping, MutableMapping
# 3rd party
from domdf_python_tools.paths import PathPlus
from domdf_python_tools.typing import PathLike
from ruamel.yaml import YAML
# this package
from configconfig.metaclass import ConfigVarMeta
from configconfig.utils import make_schema
from configconfig.validator import validate_files
__all__ = ["Parser"]
[docs]class Parser:
"""
Base class for YAML configuration parsers.
Custom parsing steps for each configuration variable can be implemented with methods in the form:
.. code-block:: python
def visit_<configuration value name>(
self,
raw_config_vars: Dict[str, Any],
) -> Any: ...
The method must return the value to set the configuration variable to,
or raise an error in the case of invalid input.
|
.. latex:vspace:: -55px
A final custom parsing step, useful when several values must be set at once,
may be implemented in the ``custom_parsing`` method:
.. code-block:: python
def custom_parsing(
self,
raw_config_vars: Mapping[str, Any],
parsed_config_vars: MutableMapping[str, Any],
filename: PathPlus,
) -> MutableMapping[str, Any]: ...
This takes the mapping of raw configuration variables,
the mapping of parsed variables (those set with the ``visit_<configuration value name>`` method),
and the configuration file name. The method must return the ``parsed_config_vars``.
"""
config_vars: List[ConfigVarMeta]
def __init__(self, allow_unknown_keys: bool = False):
self.allow_unknown_keys = allow_unknown_keys
[docs] def run(self, filename: PathLike) -> MutableMapping[str, Any]:
"""
Parse configuration from the given file.
:param filename: The filename of the YAML configuration file.
"""
filename = PathPlus(filename)
if not filename.is_file():
raise FileNotFoundError(str(filename))
with tempfile.TemporaryDirectory() as tmpdir:
tmpdir_p = PathPlus(tmpdir)
schema_file = tmpdir_p / "schema.json"
schema = make_schema(*self.config_vars)
schema["additionalProperties"] = self.allow_unknown_keys
schema_file.dump_json(schema)
validate_files(schema_file, filename)
parsed_config_vars: MutableMapping[str, Any] = {}
with filename.open() as file:
raw_config_vars: Mapping[str, Any] = YAML(typ="safe", pure=True).load(file)
for var in self.config_vars:
parsed_config_vars[var.__name__] = getattr(self, f"visit_{var.__name__}", var.get)(raw_config_vars)
return self.custom_parsing(raw_config_vars, parsed_config_vars, filename)
[docs] def custom_parsing(
self,
raw_config_vars: Mapping[str, Any],
parsed_config_vars: MutableMapping[str, Any],
filename: PathPlus,
) -> MutableMapping[str, Any]:
"""
Custom parsing step.
:param raw_config_vars: Mapping of raw configuration values loaded from the YAML configuration file.
:param parsed_config_vars: Mapping of parsed configuration values.
:param filename: The filename of the YAML configuration file.
"""
return parsed_config_vars