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from __future__ import annotations |
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import collections |
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import typing |
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from .. import _not_in |
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from .. import _stack_iter |
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from . import destructure |
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from . import match_failure |
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from .patterns import basic_patterns |
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def _stack_iteration(item) -> typing.Optional[_stack_iter.Action]: |
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target, value = item |
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if target is basic_patterns.DISCARD: |
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return None |
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if isinstance(target, basic_patterns.Pattern): |
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return _stack_iter.Yield(item) |
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destructurer = destructure.DESTRUCTURERS.get_destructurer(target) |
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if destructurer: |
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return _stack_iter.Extend(zip(destructurer(target), destructurer(value))) |
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if target != value: |
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raise match_failure.MatchFailure |
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return None |
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def match(target, value) -> MatchDict: |
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local_target = target |
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local_value = value |
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match_dict = MatchDict() |
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for local_target, local_value in _stack_iter.stack_iter( |
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(local_target, local_value), _stack_iteration |
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): |
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_not_in.not_in(container=match_dict, item=local_target.name) |
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match_dict[local_target.name] = local_value |
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return match_dict |
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def _as_name(key): |
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if isinstance(key, basic_patterns.Pattern): |
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return key.name |
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return key |
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def _multi_index(dct, key): |
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if isinstance(key, tuple): |
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return tuple(dct[sub_key] for sub_key in key) |
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if isinstance(key, dict): |
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return {name: dct[value] for (name, value) in key.items()} |
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raise KeyError(key) |
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class MatchDict(collections.abc.MutableMapping): |
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"""A MutableMapping that allows for retrieval into structures. |
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The actual keys in the mapping must be string values. Most of the mapping |
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methods will only operate on or yield string keys. The exception is |
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subscription: the "key" in subscription can be a structure made of tuples |
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and dicts. For example, ``md["a", "b"] == (md["a"], md["b"])``, and |
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``md[{1: "a"}] == {1: md["a"]}``. The typical use of this will be to |
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extract many match values at once, as in ``a, b, c == md["a", "b", "c"]``. |
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The behavior of most of the pre-defined MutableMapping methods is currently |
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neither tested nor guaranteed. |
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""" |
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def __init__(self) -> None: |
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self.data: typing.Dict[str, typing.Any] = {} |
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def __getitem__(self, key): |
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key = _as_name(key) |
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if isinstance(key, str): |
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return self.data[key] |
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return _multi_index(self, key) |
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def __setitem__(self, key, value): |
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key = _as_name(key) |
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if not isinstance(key, str): |
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raise TypeError |
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self.data[key] = value |
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def __delitem__(self, key): |
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del self.data[_as_name(key)] |
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def __iter__(self): |
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yield from self.data |
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def __len__(self): |
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return len(self.data) |
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mwchase /
python-structured-data
