Elaborate on Python support policy (#2819)

[etc/vim.git] / src / black / mode.py

diff --git a/src/black/mode.py b/src/black/mode.py
index bd4428add66a22bb6f7db0bca6082a33f28df5bd..6d45e3dc4dae23d14a2b35e791b78e6456addb1d 100644 (file)
--- a/src/black/mode.py
+++ b/src/black/mode.py
@@ -4,12 +4,14 @@ Mostly around Python language feature support per version and Black configuratio
 chosen by the user.
 """
 
+from hashlib import md5
 import sys
 
 from dataclasses import dataclass, field
-from enum import Enum
+from enum import Enum, auto
 from operator import attrgetter
 from typing import Dict, Set
+from warnings import warn
 
 if sys.version_info < (3, 8):
     from typing_extensions import Final
@@ -20,7 +22,6 @@ from black.const import DEFAULT_LINE_LENGTH
 
 
 class TargetVersion(Enum):
-    PY27 = 2
     PY33 = 3
     PY34 = 4
     PY35 = 5
@@ -30,13 +31,8 @@ class TargetVersion(Enum):
     PY39 = 9
     PY310 = 10
 
-    def is_python2(self) -> bool:
-        return self is TargetVersion.PY27
-
 
 class Feature(Enum):
-    # All string literals are unicode
-    UNICODE_LITERALS = 1
     F_STRINGS = 2
     NUMERIC_UNDERSCORES = 3
     TRAILING_COMMA_IN_CALL = 4
@@ -56,16 +52,6 @@ class Feature(Enum):
     # __future__ flags
     FUTURE_ANNOTATIONS = 51
 
-    # temporary for Python 2 deprecation
-    PRINT_STMT = 200
-    EXEC_STMT = 201
-    AUTOMATIC_PARAMETER_UNPACKING = 202
-    COMMA_STYLE_EXCEPT = 203
-    COMMA_STYLE_RAISE = 204
-    LONG_INT_LITERAL = 205
-    OCTAL_INT_LITERAL = 206
-    BACKQUOTE_REPR = 207
-
 
 FUTURE_FLAG_TO_FEATURE: Final = {
     "annotations": Feature.FUTURE_ANNOTATIONS,
@@ -73,26 +59,10 @@ FUTURE_FLAG_TO_FEATURE: Final = {
 
 
 VERSION_TO_FEATURES: Dict[TargetVersion, Set[Feature]] = {
-    TargetVersion.PY27: {
-        Feature.ASYNC_IDENTIFIERS,
-        Feature.PRINT_STMT,
-        Feature.EXEC_STMT,
-        Feature.AUTOMATIC_PARAMETER_UNPACKING,
-        Feature.COMMA_STYLE_EXCEPT,
-        Feature.COMMA_STYLE_RAISE,
-        Feature.LONG_INT_LITERAL,
-        Feature.OCTAL_INT_LITERAL,
-        Feature.BACKQUOTE_REPR,
-    },
-    TargetVersion.PY33: {Feature.UNICODE_LITERALS, Feature.ASYNC_IDENTIFIERS},
-    TargetVersion.PY34: {Feature.UNICODE_LITERALS, Feature.ASYNC_IDENTIFIERS},
-    TargetVersion.PY35: {
-        Feature.UNICODE_LITERALS,
-        Feature.TRAILING_COMMA_IN_CALL,
-        Feature.ASYNC_IDENTIFIERS,
-    },
+    TargetVersion.PY33: {Feature.ASYNC_IDENTIFIERS},
+    TargetVersion.PY34: {Feature.ASYNC_IDENTIFIERS},
+    TargetVersion.PY35: {Feature.TRAILING_COMMA_IN_CALL, Feature.ASYNC_IDENTIFIERS},
     TargetVersion.PY36: {
-        Feature.UNICODE_LITERALS,
         Feature.F_STRINGS,
         Feature.NUMERIC_UNDERSCORES,
         Feature.TRAILING_COMMA_IN_CALL,
@@ -100,7 +70,6 @@ VERSION_TO_FEATURES: Dict[TargetVersion, Set[Feature]] = {
         Feature.ASYNC_IDENTIFIERS,
     },
     TargetVersion.PY37: {
-        Feature.UNICODE_LITERALS,
         Feature.F_STRINGS,
         Feature.NUMERIC_UNDERSCORES,
         Feature.TRAILING_COMMA_IN_CALL,
@@ -109,7 +78,6 @@ VERSION_TO_FEATURES: Dict[TargetVersion, Set[Feature]] = {
         Feature.FUTURE_ANNOTATIONS,
     },
     TargetVersion.PY38: {
-        Feature.UNICODE_LITERALS,
         Feature.F_STRINGS,
         Feature.NUMERIC_UNDERSCORES,
         Feature.TRAILING_COMMA_IN_CALL,
@@ -122,7 +90,6 @@ VERSION_TO_FEATURES: Dict[TargetVersion, Set[Feature]] = {
         Feature.ANN_ASSIGN_EXTENDED_RHS,
     },
     TargetVersion.PY39: {
-        Feature.UNICODE_LITERALS,
         Feature.F_STRINGS,
         Feature.NUMERIC_UNDERSCORES,
         Feature.TRAILING_COMMA_IN_CALL,
@@ -136,7 +103,6 @@ VERSION_TO_FEATURES: Dict[TargetVersion, Set[Feature]] = {
         Feature.ANN_ASSIGN_EXTENDED_RHS,
     },
     TargetVersion.PY310: {
-        Feature.UNICODE_LITERALS,
         Feature.F_STRINGS,
         Feature.NUMERIC_UNDERSCORES,
         Feature.TRAILING_COMMA_IN_CALL,
@@ -157,6 +123,17 @@ def supports_feature(target_versions: Set[TargetVersion], feature: Feature) -> b
     return all(feature in VERSION_TO_FEATURES[version] for version in target_versions)
 
 
+class Preview(Enum):
+    """Individual preview style features."""
+
+    string_processing = auto()
+    hug_simple_powers = auto()
+
+
+class Deprecated(UserWarning):
+    """Visible deprecation warning."""
+
+
 @dataclass
 class Mode:
     target_versions: Set[TargetVersion] = field(default_factory=set)
@@ -166,6 +143,27 @@ class Mode:
     is_ipynb: bool = False
     magic_trailing_comma: bool = True
     experimental_string_processing: bool = False
+    python_cell_magics: Set[str] = field(default_factory=set)
+    preview: bool = False
+
+    def __post_init__(self) -> None:
+        if self.experimental_string_processing:
+            warn(
+                "`experimental string processing` has been included in `preview`"
+                " and deprecated. Use `preview` instead.",
+                Deprecated,
+            )
+
+    def __contains__(self, feature: Preview) -> bool:
+        """
+        Provide `Preview.FEATURE in Mode` syntax that mirrors the ``preview`` flag.
+
+        The argument is not checked and features are not differentiated.
+        They only exist to make development easier by clarifying intent.
+        """
+        if feature is Preview.string_processing:
+            return self.preview or self.experimental_string_processing
+        return self.preview
 
     def get_cache_key(self) -> str:
         if self.target_versions:
@@ -183,5 +181,7 @@ class Mode:
             str(int(self.is_ipynb)),
             str(int(self.magic_trailing_comma)),
             str(int(self.experimental_string_processing)),
+            str(int(self.preview)),
+            md5((",".join(sorted(self.python_cell_magics))).encode()).hexdigest(),
         ]
         return ".".join(parts)