108 lines
3.9 KiB
Python
108 lines
3.9 KiB
Python
# pragma pylint: disable=attribute-defined-outside-init
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"""
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This module load custom objects
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"""
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import importlib.util
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import inspect
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import logging
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from pathlib import Path
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from typing import Any, Generator, List, Optional, Tuple, Type, Union
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logger = logging.getLogger(__name__)
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class IResolver:
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"""
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This class contains all the logic to load custom classes
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"""
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# Childclasses need to override this
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object_type: Type[Any]
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@staticmethod
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def build_search_paths(config, current_path: Path, user_subdir: Optional[str] = None,
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extra_dir: Optional[str] = None) -> List[Path]:
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abs_paths: List[Path] = [current_path]
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if user_subdir:
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abs_paths.insert(0, config['user_data_dir'].joinpath(user_subdir))
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if extra_dir:
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# Add extra directory to the top of the search paths
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abs_paths.insert(0, Path(extra_dir).resolve())
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return abs_paths
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@classmethod
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def _get_valid_object(cls, module_path: Path,
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object_name: str) -> Generator[Any, None, None]:
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"""
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Generator returning objects with matching object_type and object_name in the path given.
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:param module_path: absolute path to the module
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:param object_name: Class name of the object
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:return: generator containing matching objects
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"""
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# Generate spec based on absolute path
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# Pass object_name as first argument to have logging print a reasonable name.
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spec = importlib.util.spec_from_file_location(object_name, str(module_path))
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module = importlib.util.module_from_spec(spec)
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try:
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spec.loader.exec_module(module) # type: ignore # importlib does not use typehints
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except (ModuleNotFoundError, SyntaxError) as err:
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# Catch errors in case a specific module is not installed
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logger.warning(f"Could not import {module_path} due to '{err}'")
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valid_objects_gen = (
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obj for name, obj in inspect.getmembers(module, inspect.isclass)
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if object_name == name and cls.object_type in obj.__bases__
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)
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return valid_objects_gen
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@classmethod
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def _search_object(cls, directory: Path, object_name: str,
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kwargs: dict = {}) -> Union[Tuple[Any, Path], Tuple[None, None]]:
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"""
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Search for the objectname in the given directory
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:param directory: relative or absolute directory path
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:param object_name: ClassName of the object to load
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:return: object instance
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"""
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logger.debug("Searching for %s %s in '%s'",
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cls.object_type.__name__, object_name, directory)
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for entry in directory.iterdir():
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# Only consider python files
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if not str(entry).endswith('.py'):
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logger.debug('Ignoring %s', entry)
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continue
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module_path = entry.resolve()
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obj = next(cls._get_valid_object(module_path, object_name), None)
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if obj:
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return (obj(**kwargs), module_path)
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return (None, None)
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@classmethod
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def _load_object(cls, paths: List[Path], object_name: str,
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kwargs: dict = {}) -> Optional[Any]:
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"""
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Try to load object from path list.
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"""
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for _path in paths:
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try:
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(module, module_path) = cls._search_object(directory=_path,
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object_name=object_name,
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kwargs=kwargs)
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if module:
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logger.info(
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f"Using resolved {cls.object_type.__name__.lower()[1:]} {object_name} "
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f"from '{module_path}'...")
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return module
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except FileNotFoundError:
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logger.warning('Path "%s" does not exist.', _path.resolve())
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return None
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