1"""Record of phased-in incompatible language changes.
2
3Each line is of the form:
4
5    FeatureName = "_Feature(" OptionalRelease "," MandatoryRelease ","
6                              CompilerFlag ")"
7
8where, normally, OptionalRelease < MandatoryRelease, and both are 5-tuples
9of the same form as sys.version_info:
10
11    (PY_MAJOR_VERSION, # the 2 in 2.1.0a3; an int
12     PY_MINOR_VERSION, # the 1; an int
13     PY_MICRO_VERSION, # the 0; an int
14     PY_RELEASE_LEVEL, # "alpha", "beta", "candidate" or "final"; string
15     PY_RELEASE_SERIAL # the 3; an int
16    )
17
18OptionalRelease records the first release in which
19
20    from __future__ import FeatureName
21
22was accepted.
23
24In the case of MandatoryReleases that have not yet occurred,
25MandatoryRelease predicts the release in which the feature will become part
26of the language.
27
28Else MandatoryRelease records when the feature became part of the language;
29in releases at or after that, modules no longer need
30
31    from __future__ import FeatureName
32
33to use the feature in question, but may continue to use such imports.
34
35MandatoryRelease may also be None, meaning that a planned feature got
36dropped.
37
38Instances of class _Feature have two corresponding methods,
39.getOptionalRelease() and .getMandatoryRelease().
40
41CompilerFlag is the (bitfield) flag that should be passed in the fourth
42argument to the builtin function compile() to enable the feature in
43dynamically compiled code.  This flag is stored in the .compiler_flag
44attribute on _Future instances.  These values must match the appropriate
45#defines of CO_xxx flags in Include/compile.h.
46
47No feature line is ever to be deleted from this file.
48"""
49
50all_feature_names = [
51    "nested_scopes",
52    "generators",
53    "division",
54    "absolute_import",
55    "with_statement",
56    "print_function",
57    "unicode_literals",
58]
59
60__all__ = ["all_feature_names"] + all_feature_names
61
62# The CO_xxx symbols are defined here under the same names used by
63# compile.h, so that an editor search will find them here.  However,
64# they're not exported in __all__, because they don't really belong to
65# this module.
66CO_NESTED            = 0x0010   # nested_scopes
67CO_GENERATOR_ALLOWED = 0        # generators (obsolete, was 0x1000)
68CO_FUTURE_DIVISION   = 0x2000   # division
69CO_FUTURE_ABSOLUTE_IMPORT = 0x4000 # perform absolute imports by default
70CO_FUTURE_WITH_STATEMENT  = 0x8000   # with statement
71CO_FUTURE_PRINT_FUNCTION  = 0x10000   # print function
72CO_FUTURE_UNICODE_LITERALS = 0x20000 # unicode string literals
73
74class _Feature:
75    def __init__(self, optionalRelease, mandatoryRelease, compiler_flag):
76        self.optional = optionalRelease
77        self.mandatory = mandatoryRelease
78        self.compiler_flag = compiler_flag
79
80    def getOptionalRelease(self):
81        """Return first release in which this feature was recognized.
82
83        This is a 5-tuple, of the same form as sys.version_info.
84        """
85
86        return self.optional
87
88    def getMandatoryRelease(self):
89        """Return release in which this feature will become mandatory.
90
91        This is a 5-tuple, of the same form as sys.version_info, or, if
92        the feature was dropped, is None.
93        """
94
95        return self.mandatory
96
97    def __repr__(self):
98        return "_Feature" + repr((self.optional,
99                                  self.mandatory,
100                                  self.compiler_flag))
101
102nested_scopes = _Feature((2, 1, 0, "beta",  1),
103                         (2, 2, 0, "alpha", 0),
104                         CO_NESTED)
105
106generators = _Feature((2, 2, 0, "alpha", 1),
107                      (2, 3, 0, "final", 0),
108                      CO_GENERATOR_ALLOWED)
109
110division = _Feature((2, 2, 0, "alpha", 2),
111                    (3, 0, 0, "alpha", 0),
112                    CO_FUTURE_DIVISION)
113
114absolute_import = _Feature((2, 5, 0, "alpha", 1),
115                           (3, 0, 0, "alpha", 0),
116                           CO_FUTURE_ABSOLUTE_IMPORT)
117
118with_statement = _Feature((2, 5, 0, "alpha", 1),
119                          (2, 6, 0, "alpha", 0),
120                          CO_FUTURE_WITH_STATEMENT)
121
122print_function = _Feature((2, 6, 0, "alpha", 2),
123                          (3, 0, 0, "alpha", 0),
124                          CO_FUTURE_PRINT_FUNCTION)
125
126unicode_literals = _Feature((2, 6, 0, "alpha", 2),
127                            (3, 0, 0, "alpha", 0),
128                            CO_FUTURE_UNICODE_LITERALS)
129