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      1 """Record of phased-in incompatible language changes.
      2 
      3 Each line is of the form:
      4 
      5     FeatureName = "_Feature(" OptionalRelease "," MandatoryRelease ","
      6                               CompilerFlag ")"
      7 
      8 where, normally, OptionalRelease < MandatoryRelease, and both are 5-tuples
      9 of 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 
     18 OptionalRelease records the first release in which
     19 
     20     from __future__ import FeatureName
     21 
     22 was accepted.
     23 
     24 In the case of MandatoryReleases that have not yet occurred,
     25 MandatoryRelease predicts the release in which the feature will become part
     26 of the language.
     27 
     28 Else MandatoryRelease records when the feature became part of the language;
     29 in releases at or after that, modules no longer need
     30 
     31     from __future__ import FeatureName
     32 
     33 to use the feature in question, but may continue to use such imports.
     34 
     35 MandatoryRelease may also be None, meaning that a planned feature got
     36 dropped.
     37 
     38 Instances of class _Feature have two corresponding methods,
     39 .getOptionalRelease() and .getMandatoryRelease().
     40 
     41 CompilerFlag is the (bitfield) flag that should be passed in the fourth
     42 argument to the builtin function compile() to enable the feature in
     43 dynamically compiled code.  This flag is stored in the .compiler_flag
     44 attribute on _Future instances.  These values must match the appropriate
     45 #defines of CO_xxx flags in Include/compile.h.
     46 
     47 No feature line is ever to be deleted from this file.
     48 """
     49 
     50 all_feature_names = [
     51     "nested_scopes",
     52     "generators",
     53     "division",
     54     "absolute_import",
     55     "with_statement",
     56     "print_function",
     57     "unicode_literals",
     58     "barry_as_FLUFL",
     59     "generator_stop",
     60 ]
     61 
     62 __all__ = ["all_feature_names"] + all_feature_names
     63 
     64 # The CO_xxx symbols are defined here under the same names used by
     65 # compile.h, so that an editor search will find them here.  However,
     66 # they're not exported in __all__, because they don't really belong to
     67 # this module.
     68 CO_NESTED            = 0x0010   # nested_scopes
     69 CO_GENERATOR_ALLOWED = 0        # generators (obsolete, was 0x1000)
     70 CO_FUTURE_DIVISION   = 0x2000   # division
     71 CO_FUTURE_ABSOLUTE_IMPORT = 0x4000 # perform absolute imports by default
     72 CO_FUTURE_WITH_STATEMENT  = 0x8000   # with statement
     73 CO_FUTURE_PRINT_FUNCTION  = 0x10000   # print function
     74 CO_FUTURE_UNICODE_LITERALS = 0x20000 # unicode string literals
     75 CO_FUTURE_BARRY_AS_BDFL = 0x40000
     76 CO_FUTURE_GENERATOR_STOP  = 0x80000 # StopIteration becomes RuntimeError in generators
     77 
     78 class _Feature:
     79     def __init__(self, optionalRelease, mandatoryRelease, compiler_flag):
     80         self.optional = optionalRelease
     81         self.mandatory = mandatoryRelease
     82         self.compiler_flag = compiler_flag
     83 
     84     def getOptionalRelease(self):
     85         """Return first release in which this feature was recognized.
     86 
     87         This is a 5-tuple, of the same form as sys.version_info.
     88         """
     89 
     90         return self.optional
     91 
     92     def getMandatoryRelease(self):
     93         """Return release in which this feature will become mandatory.
     94 
     95         This is a 5-tuple, of the same form as sys.version_info, or, if
     96         the feature was dropped, is None.
     97         """
     98 
     99         return self.mandatory
    100 
    101     def __repr__(self):
    102         return "_Feature" + repr((self.optional,
    103                                   self.mandatory,
    104                                   self.compiler_flag))
    105 
    106 nested_scopes = _Feature((2, 1, 0, "beta",  1),
    107                          (2, 2, 0, "alpha", 0),
    108                          CO_NESTED)
    109 
    110 generators = _Feature((2, 2, 0, "alpha", 1),
    111                       (2, 3, 0, "final", 0),
    112                       CO_GENERATOR_ALLOWED)
    113 
    114 division = _Feature((2, 2, 0, "alpha", 2),
    115                     (3, 0, 0, "alpha", 0),
    116                     CO_FUTURE_DIVISION)
    117 
    118 absolute_import = _Feature((2, 5, 0, "alpha", 1),
    119                            (3, 0, 0, "alpha", 0),
    120                            CO_FUTURE_ABSOLUTE_IMPORT)
    121 
    122 with_statement = _Feature((2, 5, 0, "alpha", 1),
    123                           (2, 6, 0, "alpha", 0),
    124                           CO_FUTURE_WITH_STATEMENT)
    125 
    126 print_function = _Feature((2, 6, 0, "alpha", 2),
    127                           (3, 0, 0, "alpha", 0),
    128                           CO_FUTURE_PRINT_FUNCTION)
    129 
    130 unicode_literals = _Feature((2, 6, 0, "alpha", 2),
    131                             (3, 0, 0, "alpha", 0),
    132                             CO_FUTURE_UNICODE_LITERALS)
    133 
    134 barry_as_FLUFL = _Feature((3, 1, 0, "alpha", 2),
    135                          (3, 9, 0, "alpha", 0),
    136                          CO_FUTURE_BARRY_AS_BDFL)
    137 
    138 generator_stop = _Feature((3, 5, 0, "beta", 1),
    139                          (3, 7, 0, "alpha", 0),
    140                          CO_FUTURE_GENERATOR_STOP)
    141