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import collections |
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3
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from ._attribute_constructor import AttributeConstructor |
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from ._match_failure import MatchFailure |
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from ._patterns import DISCARD |
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from ._patterns import Pattern |
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from ._processors import PROCESSORS |
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def not_in(container, name): |
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if name in container: |
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raise ValueError |
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def names(target): |
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"""Return every name bound by a target.""" |
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name_list = [] |
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names_seen = set() |
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to_process = [target] |
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while to_process: |
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item = to_process.pop() |
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if isinstance(item, Pattern): |
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not_in(names_seen, item.name) |
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names_seen.add(item.name) |
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name_list.append(item.name) |
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else: |
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processor = PROCESSORS.get_processor(item) |
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if processor: |
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to_process.extend(processor(item)) |
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return name_list |
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def _as_name(key): |
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if isinstance(key, 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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def __init__(self): |
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self.data = {} |
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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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74
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def _match_iteration(match_dict, target, value): |
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if target is DISCARD: |
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return |
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if isinstance(target, Pattern): |
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not_in(match_dict, target.name) |
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match_dict[target.name] = value |
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return |
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processor = PROCESSORS.get_processor(target) |
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if processor: |
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yield from zip(list(processor(target)), list(processor(value))) |
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elif target != value: |
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raise MatchFailure |
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87
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88
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def _match(target, value): |
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match_dict = MatchDict() |
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to_process = [(target, value)] |
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while to_process: |
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to_process.extend(_match_iteration(match_dict, *to_process.pop())) |
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return match_dict |
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95
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96
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class ValueMatcher: |
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"""Given a value, attempt to match against a target.""" |
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99
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def __init__(self, value): |
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self.value = value |
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self.matches = None |
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102
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103
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def match(self, target): |
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"""Match against target, generating a set of bindings.""" |
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try: |
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self.matches = _match(target, self.value) |
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except MatchFailure: |
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self.matches = None |
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return self.matches is not None |
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111
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112
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pat = AttributeConstructor(Pattern) |
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113
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114
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115
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__all__ = ['Pattern', 'ValueMatcher', 'names', 'pat'] |
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mwchase /
python-structured-data
