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1
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import keyword |
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2
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3
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DISCARD = object() |
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4
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5
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6
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class Pattern(tuple): |
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7
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"""A matcher that binds a value to a name.""" |
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8
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9
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__slots__ = () |
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10
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11
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def __new__(cls, name: str): |
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12
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if name == "_": |
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13
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return DISCARD |
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14
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if not name.isidentifier(): |
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15
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raise ValueError |
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16
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if keyword.iskeyword(name): |
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17
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raise ValueError |
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18
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return super().__new__(cls, (name,)) |
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19
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20
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@property |
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21
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def name(self): |
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22
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"""Return the name of the matcher.""" |
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23
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return tuple.__getitem__(self, 0) |
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24
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25
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def __getitem__(self, other): |
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26
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return AsPattern(self, other) |
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27
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28
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29
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class AsPattern(tuple): |
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30
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"""A matcher that contains further bindings.""" |
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31
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32
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__slots__ = () |
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33
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34
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def __new__(cls, matcher: Pattern, match): |
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35
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if match is DISCARD: |
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36
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return matcher |
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37
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return super().__new__(cls, (matcher, match)) |
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38
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39
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@property |
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40
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def matcher(self): |
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41
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"""Return the left-hand-side of the as-match.""" |
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42
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return self[0] |
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43
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44
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@property |
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45
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def match(self): |
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46
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"""Return the right-hand-side of the as-match.""" |
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47
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return self[1] |
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48
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49
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50
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class AttrPattern(tuple): |
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51
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52
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__slots__ = () |
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53
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54
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def __new__(*args, **kwargs): |
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55
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cls, *args = args |
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56
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if args: |
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57
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raise ValueError(args) |
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58
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return super(AttrPattern, cls).__new__(cls, (tuple(kwargs.items()),)) |
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59
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60
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@property |
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61
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def match_dict(self): |
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62
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return self[0] |
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63
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64
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65
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class DictPattern(tuple): |
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66
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67
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__slots__ = () |
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68
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69
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def __new__(cls, match_dict, *, exhaustive=False): |
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70
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return super(DictPattern, cls).__new__(cls, (tuple(match_dict.items()), exhaustive)) |
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71
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72
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@property |
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73
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def match_dict(self): |
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74
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return self[0] |
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75
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76
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@property |
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77
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def exhaustive(self): |
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78
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return self[1] |
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79
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mwchase /
python-structured-data
