forked from hans/Nominatim
8f4426fbc8
Code is now organized by api version. So formatting has moved to the api.v1 module. Instead of holding a separate ResultFormatter object per result format, simply move the functions to the formater collector and hand in the requested format as a parameter. Thus reorganized, the api.v1 module can export three simple functions for result formatting which in turn makes the code that uses the formatters much simpler.
57 lines
1.8 KiB
Python
57 lines
1.8 KiB
Python
# SPDX-License-Identifier: GPL-2.0-only
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#
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# This file is part of Nominatim. (https://nominatim.org)
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#
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# Copyright (C) 2023 by the Nominatim developer community.
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# For a full list of authors see the git log.
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"""
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Helper classes and functions for formating results into API responses.
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"""
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from typing import Type, TypeVar, Dict, List, Callable, Any
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from collections import defaultdict
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T = TypeVar('T') # pylint: disable=invalid-name
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FormatFunc = Callable[[T], str]
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class FormatDispatcher:
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""" Helper class to conveniently create formatting functions in
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a module using decorators.
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"""
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def __init__(self) -> None:
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self.format_functions: Dict[Type[Any], Dict[str, FormatFunc[Any]]] = defaultdict(dict)
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def format_func(self, result_class: Type[T],
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fmt: str) -> Callable[[FormatFunc[T]], FormatFunc[T]]:
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""" Decorator for a function that formats a given type of result into the
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selected format.
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"""
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def decorator(func: FormatFunc[T]) -> FormatFunc[T]:
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self.format_functions[result_class][fmt] = func
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return func
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return decorator
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def list_formats(self, result_type: Type[Any]) -> List[str]:
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""" Return a list of formats supported by this formatter.
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"""
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return list(self.format_functions[result_type].keys())
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def supports_format(self, result_type: Type[Any], fmt: str) -> bool:
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""" Check if the given format is supported by this formatter.
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"""
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return fmt in self.format_functions[result_type]
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def format_result(self, result: Any, fmt: str) -> str:
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""" Convert the given result into a string using the given format.
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The format is expected to be in the list returned by
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`list_formats()`.
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"""
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return self.format_functions[type(result)][fmt](result)
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