src/black/mode.py

   1 """Data structures configuring Black behavior.
   2
   3 Mostly around Python language feature support per version and Black configuration
   4 chosen by the user.
   5 """
   6
   7 from hashlib import sha256
   8 import sys
   9
  10 from dataclasses import dataclass, field
  11 from enum import Enum, auto
  12 from operator import attrgetter
  13 from typing import Dict, Set
  14 from warnings import warn
  15
  16 if sys.version_info < (3, 8):
  17     from typing_extensions import Final
  18 else:
  19     from typing import Final
  20
  21 from black.const import DEFAULT_LINE_LENGTH
  22
  23
  24 class TargetVersion(Enum):
  25     PY33 = 3
  26     PY34 = 4
  27     PY35 = 5
  28     PY36 = 6
  29     PY37 = 7
  30     PY38 = 8
  31     PY39 = 9
  32     PY310 = 10
  33
  34
  35 class Feature(Enum):
  36     F_STRINGS = 2
  37     NUMERIC_UNDERSCORES = 3
  38     TRAILING_COMMA_IN_CALL = 4
  39     TRAILING_COMMA_IN_DEF = 5
  40     # The following two feature-flags are mutually exclusive, and exactly one should be
  41     # set for every version of python.
  42     ASYNC_IDENTIFIERS = 6
  43     ASYNC_KEYWORDS = 7
  44     ASSIGNMENT_EXPRESSIONS = 8
  45     POS_ONLY_ARGUMENTS = 9
  46     RELAXED_DECORATORS = 10
  47     PATTERN_MATCHING = 11
  48     UNPACKING_ON_FLOW = 12
  49     ANN_ASSIGN_EXTENDED_RHS = 13
  50     FORCE_OPTIONAL_PARENTHESES = 50
  51
  52     # __future__ flags
  53     FUTURE_ANNOTATIONS = 51
  54
  55
  56 FUTURE_FLAG_TO_FEATURE: Final = {
  57     "annotations": Feature.FUTURE_ANNOTATIONS,
  58 }
  59
  60
  61 VERSION_TO_FEATURES: Dict[TargetVersion, Set[Feature]] = {
  62     TargetVersion.PY33: {Feature.ASYNC_IDENTIFIERS},
  63     TargetVersion.PY34: {Feature.ASYNC_IDENTIFIERS},
  64     TargetVersion.PY35: {Feature.TRAILING_COMMA_IN_CALL, Feature.ASYNC_IDENTIFIERS},
  65     TargetVersion.PY36: {
  66         Feature.F_STRINGS,
  67         Feature.NUMERIC_UNDERSCORES,
  68         Feature.TRAILING_COMMA_IN_CALL,
  69         Feature.TRAILING_COMMA_IN_DEF,
  70         Feature.ASYNC_IDENTIFIERS,
  71     },
  72     TargetVersion.PY37: {
  73         Feature.F_STRINGS,
  74         Feature.NUMERIC_UNDERSCORES,
  75         Feature.TRAILING_COMMA_IN_CALL,
  76         Feature.TRAILING_COMMA_IN_DEF,
  77         Feature.ASYNC_KEYWORDS,
  78         Feature.FUTURE_ANNOTATIONS,
  79     },
  80     TargetVersion.PY38: {
  81         Feature.F_STRINGS,
  82         Feature.NUMERIC_UNDERSCORES,
  83         Feature.TRAILING_COMMA_IN_CALL,
  84         Feature.TRAILING_COMMA_IN_DEF,
  85         Feature.ASYNC_KEYWORDS,
  86         Feature.FUTURE_ANNOTATIONS,
  87         Feature.ASSIGNMENT_EXPRESSIONS,
  88         Feature.POS_ONLY_ARGUMENTS,
  89         Feature.UNPACKING_ON_FLOW,
  90         Feature.ANN_ASSIGN_EXTENDED_RHS,
  91     },
  92     TargetVersion.PY39: {
  93         Feature.F_STRINGS,
  94         Feature.NUMERIC_UNDERSCORES,
  95         Feature.TRAILING_COMMA_IN_CALL,
  96         Feature.TRAILING_COMMA_IN_DEF,
  97         Feature.ASYNC_KEYWORDS,
  98         Feature.FUTURE_ANNOTATIONS,
  99         Feature.ASSIGNMENT_EXPRESSIONS,
 100         Feature.RELAXED_DECORATORS,
 101         Feature.POS_ONLY_ARGUMENTS,
 102         Feature.UNPACKING_ON_FLOW,
 103         Feature.ANN_ASSIGN_EXTENDED_RHS,
 104     },
 105     TargetVersion.PY310: {
 106         Feature.F_STRINGS,
 107         Feature.NUMERIC_UNDERSCORES,
 108         Feature.TRAILING_COMMA_IN_CALL,
 109         Feature.TRAILING_COMMA_IN_DEF,
 110         Feature.ASYNC_KEYWORDS,
 111         Feature.FUTURE_ANNOTATIONS,
 112         Feature.ASSIGNMENT_EXPRESSIONS,
 113         Feature.RELAXED_DECORATORS,
 114         Feature.POS_ONLY_ARGUMENTS,
 115         Feature.UNPACKING_ON_FLOW,
 116         Feature.ANN_ASSIGN_EXTENDED_RHS,
 117         Feature.PATTERN_MATCHING,
 118     },
 119 }
 120
 121
 122 def supports_feature(target_versions: Set[TargetVersion], feature: Feature) -> bool:
 123     return all(feature in VERSION_TO_FEATURES[version] for version in target_versions)
 124
 125
 126 class Preview(Enum):
 127     """Individual preview style features."""
 128
 129     string_processing = auto()
 130     remove_redundant_parens = auto()
 131     one_element_subscript = auto()
 132
 133
 134 class Deprecated(UserWarning):
 135     """Visible deprecation warning."""
 136
 137
 138 @dataclass
 139 class Mode:
 140     target_versions: Set[TargetVersion] = field(default_factory=set)
 141     line_length: int = DEFAULT_LINE_LENGTH
 142     string_normalization: bool = True
 143     is_pyi: bool = False
 144     is_ipynb: bool = False
 145     magic_trailing_comma: bool = True
 146     experimental_string_processing: bool = False
 147     python_cell_magics: Set[str] = field(default_factory=set)
 148     preview: bool = False
 149
 150     def __post_init__(self) -> None:
 151         if self.experimental_string_processing:
 152             warn(
 153                 "`experimental string processing` has been included in `preview`"
 154                 " and deprecated. Use `preview` instead.",
 155                 Deprecated,
 156             )
 157
 158     def __contains__(self, feature: Preview) -> bool:
 159         """
 160         Provide `Preview.FEATURE in Mode` syntax that mirrors the ``preview`` flag.
 161
 162         The argument is not checked and features are not differentiated.
 163         They only exist to make development easier by clarifying intent.
 164         """
 165         if feature is Preview.string_processing:
 166             return self.preview or self.experimental_string_processing
 167         return self.preview
 168
 169     def get_cache_key(self) -> str:
 170         if self.target_versions:
 171             version_str = ",".join(
 172                 str(version.value)
 173                 for version in sorted(self.target_versions, key=attrgetter("value"))
 174             )
 175         else:
 176             version_str = "-"
 177         parts = [
 178             version_str,
 179             str(self.line_length),
 180             str(int(self.string_normalization)),
 181             str(int(self.is_pyi)),
 182             str(int(self.is_ipynb)),
 183             str(int(self.magic_trailing_comma)),
 184             str(int(self.experimental_string_processing)),
 185             str(int(self.preview)),
 186             sha256((",".join(sorted(self.python_cell_magics))).encode()).hexdigest(),
 187         ]
 188         return ".".join(parts)