Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 1 | """functools.py - Tools for working with functions and callable objects |
Thomas Wouters | 4d70c3d | 2006-06-08 14:42:34 +0000 | [diff] [blame] | 2 | """ |
| 3 | # Python module wrapper for _functools C module |
| 4 | # to allow utilities written in Python to be added |
| 5 | # to the functools module. |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 6 | # Written by Nick Coghlan <ncoghlan at gmail.com>, |
| 7 | # Raymond Hettinger <python at rcn.com>, |
| 8 | # and Łukasz Langa <lukasz at langa.pl>. |
| 9 | # Copyright (C) 2006-2013 Python Software Foundation. |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 10 | # See C source code for _functools credits/copyright |
Thomas Wouters | 4d70c3d | 2006-06-08 14:42:34 +0000 | [diff] [blame] | 11 | |
Georg Brandl | 2e7346a | 2010-07-31 18:09:23 +0000 | [diff] [blame] | 12 | __all__ = ['update_wrapper', 'wraps', 'WRAPPER_ASSIGNMENTS', 'WRAPPER_UPDATES', |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 13 | 'total_ordering', 'cmp_to_key', 'lru_cache', 'reduce', 'partial', |
Ethan Smith | c651275 | 2018-05-26 16:38:33 -0400 | [diff] [blame] | 14 | 'partialmethod', 'singledispatch', 'singledispatchmethod'] |
Georg Brandl | 2e7346a | 2010-07-31 18:09:23 +0000 | [diff] [blame] | 15 | |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 16 | from abc import get_cache_token |
Raymond Hettinger | ec0e910 | 2012-03-16 01:16:31 -0700 | [diff] [blame] | 17 | from collections import namedtuple |
INADA Naoki | 9811e80 | 2017-09-30 16:13:02 +0900 | [diff] [blame] | 18 | # import types, weakref # Deferred to single_dispatch() |
Nick Coghlan | 457fc9a | 2016-09-10 20:00:02 +1000 | [diff] [blame] | 19 | from reprlib import recursive_repr |
Antoine Pitrou | a6a4dc8 | 2017-09-07 18:56:24 +0200 | [diff] [blame] | 20 | from _thread import RLock |
Thomas Wouters | 4d70c3d | 2006-06-08 14:42:34 +0000 | [diff] [blame] | 21 | |
Raymond Hettinger | bc8e81d | 2012-03-17 00:24:09 -0700 | [diff] [blame] | 22 | |
| 23 | ################################################################################ |
| 24 | ### update_wrapper() and wraps() decorator |
| 25 | ################################################################################ |
| 26 | |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 27 | # update_wrapper() and wraps() are tools to help write |
| 28 | # wrapper functions that can handle naive introspection |
| 29 | |
Meador Inge | ff7f64c | 2011-12-11 22:37:31 -0600 | [diff] [blame] | 30 | WRAPPER_ASSIGNMENTS = ('__module__', '__name__', '__qualname__', '__doc__', |
| 31 | '__annotations__') |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 32 | WRAPPER_UPDATES = ('__dict__',) |
| 33 | def update_wrapper(wrapper, |
| 34 | wrapped, |
| 35 | assigned = WRAPPER_ASSIGNMENTS, |
| 36 | updated = WRAPPER_UPDATES): |
| 37 | """Update a wrapper function to look like the wrapped function |
| 38 | |
| 39 | wrapper is the function to be updated |
| 40 | wrapped is the original function |
| 41 | assigned is a tuple naming the attributes assigned directly |
| 42 | from the wrapped function to the wrapper function (defaults to |
| 43 | functools.WRAPPER_ASSIGNMENTS) |
Thomas Wouters | 89f507f | 2006-12-13 04:49:30 +0000 | [diff] [blame] | 44 | updated is a tuple naming the attributes of the wrapper that |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 45 | are updated with the corresponding attribute from the wrapped |
| 46 | function (defaults to functools.WRAPPER_UPDATES) |
| 47 | """ |
| 48 | for attr in assigned: |
Nick Coghlan | 9887683 | 2010-08-17 06:17:18 +0000 | [diff] [blame] | 49 | try: |
| 50 | value = getattr(wrapped, attr) |
| 51 | except AttributeError: |
| 52 | pass |
| 53 | else: |
| 54 | setattr(wrapper, attr, value) |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 55 | for attr in updated: |
Thomas Wouters | 89f507f | 2006-12-13 04:49:30 +0000 | [diff] [blame] | 56 | getattr(wrapper, attr).update(getattr(wrapped, attr, {})) |
Nick Coghlan | 24c05bc | 2013-07-15 21:13:08 +1000 | [diff] [blame] | 57 | # Issue #17482: set __wrapped__ last so we don't inadvertently copy it |
| 58 | # from the wrapped function when updating __dict__ |
| 59 | wrapper.__wrapped__ = wrapped |
Thomas Wouters | 73e5a5b | 2006-06-08 15:35:45 +0000 | [diff] [blame] | 60 | # Return the wrapper so this can be used as a decorator via partial() |
| 61 | return wrapper |
| 62 | |
| 63 | def wraps(wrapped, |
| 64 | assigned = WRAPPER_ASSIGNMENTS, |
| 65 | updated = WRAPPER_UPDATES): |
| 66 | """Decorator factory to apply update_wrapper() to a wrapper function |
| 67 | |
| 68 | Returns a decorator that invokes update_wrapper() with the decorated |
| 69 | function as the wrapper argument and the arguments to wraps() as the |
| 70 | remaining arguments. Default arguments are as for update_wrapper(). |
| 71 | This is a convenience function to simplify applying partial() to |
| 72 | update_wrapper(). |
| 73 | """ |
| 74 | return partial(update_wrapper, wrapped=wrapped, |
| 75 | assigned=assigned, updated=updated) |
Raymond Hettinger | c50846a | 2010-04-05 18:56:31 +0000 | [diff] [blame] | 76 | |
Raymond Hettinger | bc8e81d | 2012-03-17 00:24:09 -0700 | [diff] [blame] | 77 | |
| 78 | ################################################################################ |
| 79 | ### total_ordering class decorator |
| 80 | ################################################################################ |
| 81 | |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 82 | # The total ordering functions all invoke the root magic method directly |
| 83 | # rather than using the corresponding operator. This avoids possible |
| 84 | # infinite recursion that could occur when the operator dispatch logic |
| 85 | # detects a NotImplemented result and then calls a reflected method. |
Nick Coghlan | f05d981 | 2013-10-02 00:02:03 +1000 | [diff] [blame] | 86 | |
Raymond Hettinger | ffcd849 | 2015-05-12 21:26:37 -0700 | [diff] [blame] | 87 | def _gt_from_lt(self, other, NotImplemented=NotImplemented): |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 88 | 'Return a > b. Computed by @total_ordering from (not a < b) and (a != b).' |
| 89 | op_result = self.__lt__(other) |
Nick Coghlan | f05d981 | 2013-10-02 00:02:03 +1000 | [diff] [blame] | 90 | if op_result is NotImplemented: |
Raymond Hettinger | e5db863 | 2015-01-06 22:16:10 -0800 | [diff] [blame] | 91 | return op_result |
Nick Coghlan | f05d981 | 2013-10-02 00:02:03 +1000 | [diff] [blame] | 92 | return not op_result and self != other |
| 93 | |
Raymond Hettinger | ffcd849 | 2015-05-12 21:26:37 -0700 | [diff] [blame] | 94 | def _le_from_lt(self, other, NotImplemented=NotImplemented): |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 95 | 'Return a <= b. Computed by @total_ordering from (a < b) or (a == b).' |
| 96 | op_result = self.__lt__(other) |
| 97 | return op_result or self == other |
| 98 | |
Raymond Hettinger | ffcd849 | 2015-05-12 21:26:37 -0700 | [diff] [blame] | 99 | def _ge_from_lt(self, other, NotImplemented=NotImplemented): |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 100 | 'Return a >= b. Computed by @total_ordering from (not a < b).' |
| 101 | op_result = self.__lt__(other) |
| 102 | if op_result is NotImplemented: |
Raymond Hettinger | e5db863 | 2015-01-06 22:16:10 -0800 | [diff] [blame] | 103 | return op_result |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 104 | return not op_result |
| 105 | |
Raymond Hettinger | ffcd849 | 2015-05-12 21:26:37 -0700 | [diff] [blame] | 106 | def _ge_from_le(self, other, NotImplemented=NotImplemented): |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 107 | 'Return a >= b. Computed by @total_ordering from (not a <= b) or (a == b).' |
| 108 | op_result = self.__le__(other) |
Nick Coghlan | f05d981 | 2013-10-02 00:02:03 +1000 | [diff] [blame] | 109 | if op_result is NotImplemented: |
Raymond Hettinger | e5db863 | 2015-01-06 22:16:10 -0800 | [diff] [blame] | 110 | return op_result |
Nick Coghlan | f05d981 | 2013-10-02 00:02:03 +1000 | [diff] [blame] | 111 | return not op_result or self == other |
| 112 | |
Raymond Hettinger | ffcd849 | 2015-05-12 21:26:37 -0700 | [diff] [blame] | 113 | def _lt_from_le(self, other, NotImplemented=NotImplemented): |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 114 | 'Return a < b. Computed by @total_ordering from (a <= b) and (a != b).' |
| 115 | op_result = self.__le__(other) |
Nick Coghlan | f05d981 | 2013-10-02 00:02:03 +1000 | [diff] [blame] | 116 | if op_result is NotImplemented: |
Raymond Hettinger | e5db863 | 2015-01-06 22:16:10 -0800 | [diff] [blame] | 117 | return op_result |
Nick Coghlan | f05d981 | 2013-10-02 00:02:03 +1000 | [diff] [blame] | 118 | return op_result and self != other |
| 119 | |
Raymond Hettinger | ffcd849 | 2015-05-12 21:26:37 -0700 | [diff] [blame] | 120 | def _gt_from_le(self, other, NotImplemented=NotImplemented): |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 121 | 'Return a > b. Computed by @total_ordering from (not a <= b).' |
| 122 | op_result = self.__le__(other) |
| 123 | if op_result is NotImplemented: |
Raymond Hettinger | e5db863 | 2015-01-06 22:16:10 -0800 | [diff] [blame] | 124 | return op_result |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 125 | return not op_result |
| 126 | |
Raymond Hettinger | ffcd849 | 2015-05-12 21:26:37 -0700 | [diff] [blame] | 127 | def _lt_from_gt(self, other, NotImplemented=NotImplemented): |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 128 | 'Return a < b. Computed by @total_ordering from (not a > b) and (a != b).' |
| 129 | op_result = self.__gt__(other) |
| 130 | if op_result is NotImplemented: |
Raymond Hettinger | e5db863 | 2015-01-06 22:16:10 -0800 | [diff] [blame] | 131 | return op_result |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 132 | return not op_result and self != other |
| 133 | |
Raymond Hettinger | ffcd849 | 2015-05-12 21:26:37 -0700 | [diff] [blame] | 134 | def _ge_from_gt(self, other, NotImplemented=NotImplemented): |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 135 | 'Return a >= b. Computed by @total_ordering from (a > b) or (a == b).' |
| 136 | op_result = self.__gt__(other) |
| 137 | return op_result or self == other |
| 138 | |
Raymond Hettinger | ffcd849 | 2015-05-12 21:26:37 -0700 | [diff] [blame] | 139 | def _le_from_gt(self, other, NotImplemented=NotImplemented): |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 140 | 'Return a <= b. Computed by @total_ordering from (not a > b).' |
| 141 | op_result = self.__gt__(other) |
| 142 | if op_result is NotImplemented: |
Raymond Hettinger | e5db863 | 2015-01-06 22:16:10 -0800 | [diff] [blame] | 143 | return op_result |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 144 | return not op_result |
| 145 | |
Raymond Hettinger | ffcd849 | 2015-05-12 21:26:37 -0700 | [diff] [blame] | 146 | def _le_from_ge(self, other, NotImplemented=NotImplemented): |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 147 | 'Return a <= b. Computed by @total_ordering from (not a >= b) or (a == b).' |
| 148 | op_result = self.__ge__(other) |
| 149 | if op_result is NotImplemented: |
Raymond Hettinger | e5db863 | 2015-01-06 22:16:10 -0800 | [diff] [blame] | 150 | return op_result |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 151 | return not op_result or self == other |
| 152 | |
Raymond Hettinger | ffcd849 | 2015-05-12 21:26:37 -0700 | [diff] [blame] | 153 | def _gt_from_ge(self, other, NotImplemented=NotImplemented): |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 154 | 'Return a > b. Computed by @total_ordering from (a >= b) and (a != b).' |
| 155 | op_result = self.__ge__(other) |
| 156 | if op_result is NotImplemented: |
Raymond Hettinger | e5db863 | 2015-01-06 22:16:10 -0800 | [diff] [blame] | 157 | return op_result |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 158 | return op_result and self != other |
| 159 | |
Raymond Hettinger | ffcd849 | 2015-05-12 21:26:37 -0700 | [diff] [blame] | 160 | def _lt_from_ge(self, other, NotImplemented=NotImplemented): |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 161 | 'Return a < b. Computed by @total_ordering from (not a >= b).' |
| 162 | op_result = self.__ge__(other) |
| 163 | if op_result is NotImplemented: |
Raymond Hettinger | e5db863 | 2015-01-06 22:16:10 -0800 | [diff] [blame] | 164 | return op_result |
Raymond Hettinger | 0603d30 | 2015-01-05 21:52:10 -0800 | [diff] [blame] | 165 | return not op_result |
Raymond Hettinger | c50846a | 2010-04-05 18:56:31 +0000 | [diff] [blame] | 166 | |
Raymond Hettinger | 1a8ada8 | 2015-01-13 22:57:35 -0800 | [diff] [blame] | 167 | _convert = { |
| 168 | '__lt__': [('__gt__', _gt_from_lt), |
| 169 | ('__le__', _le_from_lt), |
| 170 | ('__ge__', _ge_from_lt)], |
| 171 | '__le__': [('__ge__', _ge_from_le), |
| 172 | ('__lt__', _lt_from_le), |
| 173 | ('__gt__', _gt_from_le)], |
| 174 | '__gt__': [('__lt__', _lt_from_gt), |
| 175 | ('__ge__', _ge_from_gt), |
| 176 | ('__le__', _le_from_gt)], |
| 177 | '__ge__': [('__le__', _le_from_ge), |
| 178 | ('__gt__', _gt_from_ge), |
| 179 | ('__lt__', _lt_from_ge)] |
| 180 | } |
| 181 | |
Raymond Hettinger | c50846a | 2010-04-05 18:56:31 +0000 | [diff] [blame] | 182 | def total_ordering(cls): |
Georg Brandl | e5a2673 | 2010-05-19 21:06:36 +0000 | [diff] [blame] | 183 | """Class decorator that fills in missing ordering methods""" |
Raymond Hettinger | 3255c63 | 2010-09-16 00:31:21 +0000 | [diff] [blame] | 184 | # Find user-defined comparisons (not those inherited from object). |
Raymond Hettinger | 15ce0be | 2017-09-05 09:40:44 -0700 | [diff] [blame] | 185 | roots = {op for op in _convert if getattr(cls, op, None) is not getattr(object, op, None)} |
Raymond Hettinger | 56de7e2 | 2010-04-10 16:59:03 +0000 | [diff] [blame] | 186 | if not roots: |
| 187 | raise ValueError('must define at least one ordering operation: < > <= >=') |
| 188 | root = max(roots) # prefer __lt__ to __le__ to __gt__ to __ge__ |
Raymond Hettinger | 1a8ada8 | 2015-01-13 22:57:35 -0800 | [diff] [blame] | 189 | for opname, opfunc in _convert[root]: |
Raymond Hettinger | c50846a | 2010-04-05 18:56:31 +0000 | [diff] [blame] | 190 | if opname not in roots: |
| 191 | opfunc.__name__ = opname |
Raymond Hettinger | c50846a | 2010-04-05 18:56:31 +0000 | [diff] [blame] | 192 | setattr(cls, opname, opfunc) |
| 193 | return cls |
| 194 | |
Raymond Hettinger | bc8e81d | 2012-03-17 00:24:09 -0700 | [diff] [blame] | 195 | |
| 196 | ################################################################################ |
| 197 | ### cmp_to_key() function converter |
| 198 | ################################################################################ |
| 199 | |
Raymond Hettinger | c50846a | 2010-04-05 18:56:31 +0000 | [diff] [blame] | 200 | def cmp_to_key(mycmp): |
Georg Brandl | e5a2673 | 2010-05-19 21:06:36 +0000 | [diff] [blame] | 201 | """Convert a cmp= function into a key= function""" |
Raymond Hettinger | c50846a | 2010-04-05 18:56:31 +0000 | [diff] [blame] | 202 | class K(object): |
Raymond Hettinger | a0d1d96 | 2011-03-21 17:50:28 -0700 | [diff] [blame] | 203 | __slots__ = ['obj'] |
Raymond Hettinger | 7ab9e22 | 2011-04-05 02:33:54 -0700 | [diff] [blame] | 204 | def __init__(self, obj): |
Raymond Hettinger | c50846a | 2010-04-05 18:56:31 +0000 | [diff] [blame] | 205 | self.obj = obj |
| 206 | def __lt__(self, other): |
| 207 | return mycmp(self.obj, other.obj) < 0 |
| 208 | def __gt__(self, other): |
| 209 | return mycmp(self.obj, other.obj) > 0 |
| 210 | def __eq__(self, other): |
| 211 | return mycmp(self.obj, other.obj) == 0 |
| 212 | def __le__(self, other): |
| 213 | return mycmp(self.obj, other.obj) <= 0 |
| 214 | def __ge__(self, other): |
| 215 | return mycmp(self.obj, other.obj) >= 0 |
Raymond Hettinger | 003be52 | 2011-05-03 11:01:32 -0700 | [diff] [blame] | 216 | __hash__ = None |
Raymond Hettinger | c50846a | 2010-04-05 18:56:31 +0000 | [diff] [blame] | 217 | return K |
Georg Brandl | 2e7346a | 2010-07-31 18:09:23 +0000 | [diff] [blame] | 218 | |
Raymond Hettinger | 7ab9e22 | 2011-04-05 02:33:54 -0700 | [diff] [blame] | 219 | try: |
| 220 | from _functools import cmp_to_key |
Brett Cannon | cd171c8 | 2013-07-04 17:43:24 -0400 | [diff] [blame] | 221 | except ImportError: |
Raymond Hettinger | 7ab9e22 | 2011-04-05 02:33:54 -0700 | [diff] [blame] | 222 | pass |
| 223 | |
Raymond Hettinger | bc8e81d | 2012-03-17 00:24:09 -0700 | [diff] [blame] | 224 | |
| 225 | ################################################################################ |
madman-bob | e25d5fc | 2018-10-25 15:02:10 +0100 | [diff] [blame] | 226 | ### reduce() sequence to a single item |
| 227 | ################################################################################ |
| 228 | |
| 229 | _initial_missing = object() |
| 230 | |
| 231 | def reduce(function, sequence, initial=_initial_missing): |
| 232 | """ |
| 233 | reduce(function, sequence[, initial]) -> value |
| 234 | |
| 235 | Apply a function of two arguments cumulatively to the items of a sequence, |
| 236 | from left to right, so as to reduce the sequence to a single value. |
| 237 | For example, reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) calculates |
| 238 | ((((1+2)+3)+4)+5). If initial is present, it is placed before the items |
| 239 | of the sequence in the calculation, and serves as a default when the |
| 240 | sequence is empty. |
| 241 | """ |
| 242 | |
| 243 | it = iter(sequence) |
| 244 | |
| 245 | if initial is _initial_missing: |
| 246 | try: |
| 247 | value = next(it) |
| 248 | except StopIteration: |
| 249 | raise TypeError("reduce() of empty sequence with no initial value") from None |
| 250 | else: |
| 251 | value = initial |
| 252 | |
| 253 | for element in it: |
| 254 | value = function(value, element) |
| 255 | |
| 256 | return value |
| 257 | |
| 258 | try: |
| 259 | from _functools import reduce |
| 260 | except ImportError: |
| 261 | pass |
| 262 | |
| 263 | |
| 264 | ################################################################################ |
Antoine Pitrou | b5b3714 | 2012-11-13 21:35:40 +0100 | [diff] [blame] | 265 | ### partial() argument application |
| 266 | ################################################################################ |
| 267 | |
Nick Coghlan | f4cb48a | 2013-11-03 16:41:46 +1000 | [diff] [blame] | 268 | # Purely functional, no descriptor behaviour |
Nick Coghlan | 457fc9a | 2016-09-10 20:00:02 +1000 | [diff] [blame] | 269 | class partial: |
Nick Coghlan | f4cb48a | 2013-11-03 16:41:46 +1000 | [diff] [blame] | 270 | """New function with partial application of the given arguments |
Antoine Pitrou | b5b3714 | 2012-11-13 21:35:40 +0100 | [diff] [blame] | 271 | and keywords. |
| 272 | """ |
Alexander Belopolsky | e49af34 | 2015-03-01 15:08:17 -0500 | [diff] [blame] | 273 | |
Nick Coghlan | 457fc9a | 2016-09-10 20:00:02 +1000 | [diff] [blame] | 274 | __slots__ = "func", "args", "keywords", "__dict__", "__weakref__" |
| 275 | |
Serhiy Storchaka | 2085bd0 | 2019-06-01 11:00:15 +0300 | [diff] [blame] | 276 | def __new__(cls, func, /, *args, **keywords): |
Nick Coghlan | 457fc9a | 2016-09-10 20:00:02 +1000 | [diff] [blame] | 277 | if not callable(func): |
| 278 | raise TypeError("the first argument must be callable") |
Nick Coghlan | 457fc9a | 2016-09-10 20:00:02 +1000 | [diff] [blame] | 279 | |
| 280 | if hasattr(func, "func"): |
| 281 | args = func.args + args |
Serhiy Storchaka | da08470 | 2019-03-27 08:02:28 +0200 | [diff] [blame] | 282 | keywords = {**func.keywords, **keywords} |
Nick Coghlan | 457fc9a | 2016-09-10 20:00:02 +1000 | [diff] [blame] | 283 | func = func.func |
| 284 | |
| 285 | self = super(partial, cls).__new__(cls) |
| 286 | |
| 287 | self.func = func |
| 288 | self.args = args |
| 289 | self.keywords = keywords |
| 290 | return self |
| 291 | |
Serhiy Storchaka | 2085bd0 | 2019-06-01 11:00:15 +0300 | [diff] [blame] | 292 | def __call__(self, /, *args, **keywords): |
Serhiy Storchaka | da08470 | 2019-03-27 08:02:28 +0200 | [diff] [blame] | 293 | keywords = {**self.keywords, **keywords} |
| 294 | return self.func(*self.args, *args, **keywords) |
Nick Coghlan | 457fc9a | 2016-09-10 20:00:02 +1000 | [diff] [blame] | 295 | |
| 296 | @recursive_repr() |
| 297 | def __repr__(self): |
| 298 | qualname = type(self).__qualname__ |
| 299 | args = [repr(self.func)] |
| 300 | args.extend(repr(x) for x in self.args) |
| 301 | args.extend(f"{k}={v!r}" for (k, v) in self.keywords.items()) |
| 302 | if type(self).__module__ == "functools": |
| 303 | return f"functools.{qualname}({', '.join(args)})" |
| 304 | return f"{qualname}({', '.join(args)})" |
| 305 | |
| 306 | def __reduce__(self): |
| 307 | return type(self), (self.func,), (self.func, self.args, |
| 308 | self.keywords or None, self.__dict__ or None) |
| 309 | |
| 310 | def __setstate__(self, state): |
| 311 | if not isinstance(state, tuple): |
| 312 | raise TypeError("argument to __setstate__ must be a tuple") |
| 313 | if len(state) != 4: |
| 314 | raise TypeError(f"expected 4 items in state, got {len(state)}") |
| 315 | func, args, kwds, namespace = state |
| 316 | if (not callable(func) or not isinstance(args, tuple) or |
| 317 | (kwds is not None and not isinstance(kwds, dict)) or |
| 318 | (namespace is not None and not isinstance(namespace, dict))): |
| 319 | raise TypeError("invalid partial state") |
| 320 | |
| 321 | args = tuple(args) # just in case it's a subclass |
| 322 | if kwds is None: |
| 323 | kwds = {} |
| 324 | elif type(kwds) is not dict: # XXX does it need to be *exactly* dict? |
| 325 | kwds = dict(kwds) |
| 326 | if namespace is None: |
| 327 | namespace = {} |
| 328 | |
| 329 | self.__dict__ = namespace |
| 330 | self.func = func |
| 331 | self.args = args |
| 332 | self.keywords = kwds |
Antoine Pitrou | b5b3714 | 2012-11-13 21:35:40 +0100 | [diff] [blame] | 333 | |
| 334 | try: |
| 335 | from _functools import partial |
Brett Cannon | cd171c8 | 2013-07-04 17:43:24 -0400 | [diff] [blame] | 336 | except ImportError: |
Antoine Pitrou | b5b3714 | 2012-11-13 21:35:40 +0100 | [diff] [blame] | 337 | pass |
| 338 | |
Nick Coghlan | f4cb48a | 2013-11-03 16:41:46 +1000 | [diff] [blame] | 339 | # Descriptor version |
| 340 | class partialmethod(object): |
| 341 | """Method descriptor with partial application of the given arguments |
| 342 | and keywords. |
| 343 | |
| 344 | Supports wrapping existing descriptors and handles non-descriptor |
| 345 | callables as instance methods. |
| 346 | """ |
| 347 | |
Serhiy Storchaka | 42a139e | 2019-04-01 09:16:35 +0300 | [diff] [blame] | 348 | def __init__(*args, **keywords): |
| 349 | if len(args) >= 2: |
| 350 | self, func, *args = args |
| 351 | elif not args: |
| 352 | raise TypeError("descriptor '__init__' of partialmethod " |
| 353 | "needs an argument") |
| 354 | elif 'func' in keywords: |
| 355 | func = keywords.pop('func') |
| 356 | self, *args = args |
| 357 | import warnings |
| 358 | warnings.warn("Passing 'func' as keyword argument is deprecated", |
| 359 | DeprecationWarning, stacklevel=2) |
| 360 | else: |
| 361 | raise TypeError("type 'partialmethod' takes at least one argument, " |
| 362 | "got %d" % (len(args)-1)) |
| 363 | args = tuple(args) |
| 364 | |
Nick Coghlan | f4cb48a | 2013-11-03 16:41:46 +1000 | [diff] [blame] | 365 | if not callable(func) and not hasattr(func, "__get__"): |
| 366 | raise TypeError("{!r} is not callable or a descriptor" |
| 367 | .format(func)) |
| 368 | |
| 369 | # func could be a descriptor like classmethod which isn't callable, |
| 370 | # so we can't inherit from partial (it verifies func is callable) |
| 371 | if isinstance(func, partialmethod): |
| 372 | # flattening is mandatory in order to place cls/self before all |
| 373 | # other arguments |
| 374 | # it's also more efficient since only one function will be called |
| 375 | self.func = func.func |
| 376 | self.args = func.args + args |
Serhiy Storchaka | da08470 | 2019-03-27 08:02:28 +0200 | [diff] [blame] | 377 | self.keywords = {**func.keywords, **keywords} |
Nick Coghlan | f4cb48a | 2013-11-03 16:41:46 +1000 | [diff] [blame] | 378 | else: |
| 379 | self.func = func |
| 380 | self.args = args |
| 381 | self.keywords = keywords |
Serhiy Storchaka | d53cf99 | 2019-05-06 22:40:27 +0300 | [diff] [blame] | 382 | __init__.__text_signature__ = '($self, func, /, *args, **keywords)' |
Nick Coghlan | f4cb48a | 2013-11-03 16:41:46 +1000 | [diff] [blame] | 383 | |
| 384 | def __repr__(self): |
| 385 | args = ", ".join(map(repr, self.args)) |
| 386 | keywords = ", ".join("{}={!r}".format(k, v) |
| 387 | for k, v in self.keywords.items()) |
| 388 | format_string = "{module}.{cls}({func}, {args}, {keywords})" |
| 389 | return format_string.format(module=self.__class__.__module__, |
Serhiy Storchaka | 521e586 | 2014-07-22 15:00:37 +0300 | [diff] [blame] | 390 | cls=self.__class__.__qualname__, |
Nick Coghlan | f4cb48a | 2013-11-03 16:41:46 +1000 | [diff] [blame] | 391 | func=self.func, |
| 392 | args=args, |
| 393 | keywords=keywords) |
| 394 | |
| 395 | def _make_unbound_method(self): |
Serhiy Storchaka | 2085bd0 | 2019-06-01 11:00:15 +0300 | [diff] [blame] | 396 | def _method(cls_or_self, /, *args, **keywords): |
Serhiy Storchaka | da08470 | 2019-03-27 08:02:28 +0200 | [diff] [blame] | 397 | keywords = {**self.keywords, **keywords} |
| 398 | return self.func(cls_or_self, *self.args, *args, **keywords) |
Nick Coghlan | f4cb48a | 2013-11-03 16:41:46 +1000 | [diff] [blame] | 399 | _method.__isabstractmethod__ = self.__isabstractmethod__ |
Yury Selivanov | da5fe4f | 2014-01-27 17:28:37 -0500 | [diff] [blame] | 400 | _method._partialmethod = self |
Nick Coghlan | f4cb48a | 2013-11-03 16:41:46 +1000 | [diff] [blame] | 401 | return _method |
| 402 | |
| 403 | def __get__(self, obj, cls): |
| 404 | get = getattr(self.func, "__get__", None) |
| 405 | result = None |
| 406 | if get is not None: |
| 407 | new_func = get(obj, cls) |
| 408 | if new_func is not self.func: |
| 409 | # Assume __get__ returning something new indicates the |
| 410 | # creation of an appropriate callable |
| 411 | result = partial(new_func, *self.args, **self.keywords) |
| 412 | try: |
| 413 | result.__self__ = new_func.__self__ |
| 414 | except AttributeError: |
| 415 | pass |
| 416 | if result is None: |
| 417 | # If the underlying descriptor didn't do anything, treat this |
| 418 | # like an instance method |
| 419 | result = self._make_unbound_method().__get__(obj, cls) |
| 420 | return result |
| 421 | |
| 422 | @property |
| 423 | def __isabstractmethod__(self): |
| 424 | return getattr(self.func, "__isabstractmethod__", False) |
| 425 | |
Pablo Galindo | 7cd2543 | 2018-10-26 12:19:14 +0100 | [diff] [blame] | 426 | # Helper functions |
| 427 | |
| 428 | def _unwrap_partial(func): |
| 429 | while isinstance(func, partial): |
| 430 | func = func.func |
| 431 | return func |
Antoine Pitrou | b5b3714 | 2012-11-13 21:35:40 +0100 | [diff] [blame] | 432 | |
| 433 | ################################################################################ |
Raymond Hettinger | bc8e81d | 2012-03-17 00:24:09 -0700 | [diff] [blame] | 434 | ### LRU Cache function decorator |
| 435 | ################################################################################ |
| 436 | |
Raymond Hettinger | dce583e | 2012-03-16 22:12:20 -0700 | [diff] [blame] | 437 | _CacheInfo = namedtuple("CacheInfo", ["hits", "misses", "maxsize", "currsize"]) |
Nick Coghlan | 234515a | 2010-11-30 06:19:46 +0000 | [diff] [blame] | 438 | |
Raymond Hettinger | 0c9050c | 2012-06-04 00:21:14 -0700 | [diff] [blame] | 439 | class _HashedSeq(list): |
Raymond Hettinger | f96b2b0 | 2013-03-08 21:11:55 -0700 | [diff] [blame] | 440 | """ This class guarantees that hash() will be called no more than once |
| 441 | per element. This is important because the lru_cache() will hash |
| 442 | the key multiple times on a cache miss. |
| 443 | |
| 444 | """ |
| 445 | |
Raymond Hettinger | 9acbb60 | 2012-04-30 22:32:16 -0700 | [diff] [blame] | 446 | __slots__ = 'hashvalue' |
| 447 | |
Raymond Hettinger | 0c9050c | 2012-06-04 00:21:14 -0700 | [diff] [blame] | 448 | def __init__(self, tup, hash=hash): |
| 449 | self[:] = tup |
| 450 | self.hashvalue = hash(tup) |
Raymond Hettinger | 9acbb60 | 2012-04-30 22:32:16 -0700 | [diff] [blame] | 451 | |
| 452 | def __hash__(self): |
| 453 | return self.hashvalue |
| 454 | |
Raymond Hettinger | 0c9050c | 2012-06-04 00:21:14 -0700 | [diff] [blame] | 455 | def _make_key(args, kwds, typed, |
| 456 | kwd_mark = (object(),), |
Raymond Hettinger | d8080c0 | 2019-01-26 03:02:00 -0500 | [diff] [blame] | 457 | fasttypes = {int, str}, |
Raymond Hettinger | 4ee3914 | 2017-01-08 17:28:20 -0800 | [diff] [blame] | 458 | tuple=tuple, type=type, len=len): |
Raymond Hettinger | f96b2b0 | 2013-03-08 21:11:55 -0700 | [diff] [blame] | 459 | """Make a cache key from optionally typed positional and keyword arguments |
| 460 | |
| 461 | The key is constructed in a way that is flat as possible rather than |
| 462 | as a nested structure that would take more memory. |
| 463 | |
| 464 | If there is only a single argument and its data type is known to cache |
| 465 | its hash value, then that argument is returned without a wrapper. This |
| 466 | saves space and improves lookup speed. |
| 467 | |
| 468 | """ |
Raymond Hettinger | 5503709 | 2017-09-04 17:47:53 -0700 | [diff] [blame] | 469 | # All of code below relies on kwds preserving the order input by the user. |
| 470 | # Formerly, we sorted() the kwds before looping. The new way is *much* |
| 471 | # faster; however, it means that f(x=1, y=2) will now be treated as a |
| 472 | # distinct call from f(y=2, x=1) which will be cached separately. |
Raymond Hettinger | 0c9050c | 2012-06-04 00:21:14 -0700 | [diff] [blame] | 473 | key = args |
| 474 | if kwds: |
Raymond Hettinger | 0c9050c | 2012-06-04 00:21:14 -0700 | [diff] [blame] | 475 | key += kwd_mark |
Raymond Hettinger | 4ee3914 | 2017-01-08 17:28:20 -0800 | [diff] [blame] | 476 | for item in kwds.items(): |
Raymond Hettinger | 0c9050c | 2012-06-04 00:21:14 -0700 | [diff] [blame] | 477 | key += item |
| 478 | if typed: |
| 479 | key += tuple(type(v) for v in args) |
| 480 | if kwds: |
Raymond Hettinger | 4ee3914 | 2017-01-08 17:28:20 -0800 | [diff] [blame] | 481 | key += tuple(type(v) for v in kwds.values()) |
Raymond Hettinger | 0c9050c | 2012-06-04 00:21:14 -0700 | [diff] [blame] | 482 | elif len(key) == 1 and type(key[0]) in fasttypes: |
| 483 | return key[0] |
| 484 | return _HashedSeq(key) |
| 485 | |
Raymond Hettinger | 010ce32 | 2012-05-19 21:20:48 -0700 | [diff] [blame] | 486 | def lru_cache(maxsize=128, typed=False): |
Benjamin Peterson | 1f594ad | 2010-08-08 13:17:07 +0000 | [diff] [blame] | 487 | """Least-recently-used cache decorator. |
Georg Brandl | 2e7346a | 2010-07-31 18:09:23 +0000 | [diff] [blame] | 488 | |
Raymond Hettinger | c79fb0e | 2010-12-01 03:45:41 +0000 | [diff] [blame] | 489 | If *maxsize* is set to None, the LRU features are disabled and the cache |
| 490 | can grow without bound. |
| 491 | |
Raymond Hettinger | cd9fdfd | 2011-10-20 08:57:45 -0700 | [diff] [blame] | 492 | If *typed* is True, arguments of different types will be cached separately. |
| 493 | For example, f(3.0) and f(3) will be treated as distinct calls with |
| 494 | distinct results. |
| 495 | |
Georg Brandl | 2e7346a | 2010-07-31 18:09:23 +0000 | [diff] [blame] | 496 | Arguments to the cached function must be hashable. |
Raymond Hettinger | 5fa40c0 | 2010-11-25 08:11:57 +0000 | [diff] [blame] | 497 | |
Raymond Hettinger | 7f7a5a7 | 2012-03-30 21:50:40 -0700 | [diff] [blame] | 498 | View the cache statistics named tuple (hits, misses, maxsize, currsize) |
| 499 | with f.cache_info(). Clear the cache and statistics with f.cache_clear(). |
Raymond Hettinger | 00f2f97 | 2010-12-01 00:47:56 +0000 | [diff] [blame] | 500 | Access the underlying function with f.__wrapped__. |
Raymond Hettinger | 5fa40c0 | 2010-11-25 08:11:57 +0000 | [diff] [blame] | 501 | |
| 502 | See: http://en.wikipedia.org/wiki/Cache_algorithms#Least_Recently_Used |
Georg Brandl | 2e7346a | 2010-07-31 18:09:23 +0000 | [diff] [blame] | 503 | |
Benjamin Peterson | 1f594ad | 2010-08-08 13:17:07 +0000 | [diff] [blame] | 504 | """ |
Raymond Hettinger | 1ff50df | 2012-03-30 13:15:48 -0700 | [diff] [blame] | 505 | |
Raymond Hettinger | 5fa40c0 | 2010-11-25 08:11:57 +0000 | [diff] [blame] | 506 | # Users should only access the lru_cache through its public API: |
Raymond Hettinger | 5e20bab | 2010-11-30 07:13:04 +0000 | [diff] [blame] | 507 | # cache_info, cache_clear, and f.__wrapped__ |
Raymond Hettinger | 5fa40c0 | 2010-11-25 08:11:57 +0000 | [diff] [blame] | 508 | # The internals of the lru_cache are encapsulated for thread safety and |
| 509 | # to allow the implementation to change (including a possible C version). |
| 510 | |
Raymond Hettinger | d8080c0 | 2019-01-26 03:02:00 -0500 | [diff] [blame] | 511 | if isinstance(maxsize, int): |
Raymond Hettinger | b821868 | 2019-05-26 11:27:35 -0700 | [diff] [blame] | 512 | # Negative maxsize is treated as 0 |
Raymond Hettinger | d8080c0 | 2019-01-26 03:02:00 -0500 | [diff] [blame] | 513 | if maxsize < 0: |
| 514 | maxsize = 0 |
Raymond Hettinger | b821868 | 2019-05-26 11:27:35 -0700 | [diff] [blame] | 515 | elif callable(maxsize) and isinstance(typed, bool): |
| 516 | # The user_function was passed in directly via the maxsize argument |
| 517 | user_function, maxsize = maxsize, 128 |
| 518 | wrapper = _lru_cache_wrapper(user_function, maxsize, typed, _CacheInfo) |
| 519 | return update_wrapper(wrapper, user_function) |
Raymond Hettinger | d8080c0 | 2019-01-26 03:02:00 -0500 | [diff] [blame] | 520 | elif maxsize is not None: |
Raymond Hettinger | b821868 | 2019-05-26 11:27:35 -0700 | [diff] [blame] | 521 | raise TypeError( |
| 522 | 'Expected first argument to be an integer, a callable, or None') |
Raymond Hettinger | 4d58897 | 2014-08-12 12:44:52 -0700 | [diff] [blame] | 523 | |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 524 | def decorating_function(user_function): |
| 525 | wrapper = _lru_cache_wrapper(user_function, maxsize, typed, _CacheInfo) |
| 526 | return update_wrapper(wrapper, user_function) |
| 527 | |
| 528 | return decorating_function |
| 529 | |
| 530 | def _lru_cache_wrapper(user_function, maxsize, typed, _CacheInfo): |
Raymond Hettinger | 9f0ab9f | 2012-04-29 14:55:27 -0700 | [diff] [blame] | 531 | # Constants shared by all lru cache instances: |
Raymond Hettinger | b6b98c0 | 2012-04-29 18:09:02 -0700 | [diff] [blame] | 532 | sentinel = object() # unique object used to signal cache misses |
Raymond Hettinger | 0c9050c | 2012-06-04 00:21:14 -0700 | [diff] [blame] | 533 | make_key = _make_key # build a key from the function arguments |
Raymond Hettinger | 9f0ab9f | 2012-04-29 14:55:27 -0700 | [diff] [blame] | 534 | PREV, NEXT, KEY, RESULT = 0, 1, 2, 3 # names for the link fields |
| 535 | |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 536 | cache = {} |
| 537 | hits = misses = 0 |
| 538 | full = False |
| 539 | cache_get = cache.get # bound method to lookup a key or return None |
Raymond Hettinger | b2d4b3d | 2016-12-16 14:59:37 -0800 | [diff] [blame] | 540 | cache_len = cache.__len__ # get cache size without calling len() |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 541 | lock = RLock() # because linkedlist updates aren't threadsafe |
| 542 | root = [] # root of the circular doubly linked list |
| 543 | root[:] = [root, root, None, None] # initialize by pointing to self |
Raymond Hettinger | 6e8c817 | 2012-03-16 16:53:05 -0700 | [diff] [blame] | 544 | |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 545 | if maxsize == 0: |
Raymond Hettinger | 7e0c581 | 2012-03-17 15:10:24 -0700 | [diff] [blame] | 546 | |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 547 | def wrapper(*args, **kwds): |
Raymond Hettinger | ffdf1c3 | 2019-01-31 15:03:38 -0800 | [diff] [blame] | 548 | # No caching -- just a statistics update |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 549 | nonlocal misses |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 550 | misses += 1 |
Raymond Hettinger | ffdf1c3 | 2019-01-31 15:03:38 -0800 | [diff] [blame] | 551 | result = user_function(*args, **kwds) |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 552 | return result |
| 553 | |
| 554 | elif maxsize is None: |
| 555 | |
| 556 | def wrapper(*args, **kwds): |
| 557 | # Simple caching without ordering or size limit |
| 558 | nonlocal hits, misses |
| 559 | key = make_key(args, kwds, typed) |
| 560 | result = cache_get(key, sentinel) |
| 561 | if result is not sentinel: |
| 562 | hits += 1 |
Raymond Hettinger | 7e0c581 | 2012-03-17 15:10:24 -0700 | [diff] [blame] | 563 | return result |
Raymond Hettinger | ffdf1c3 | 2019-01-31 15:03:38 -0800 | [diff] [blame] | 564 | misses += 1 |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 565 | result = user_function(*args, **kwds) |
| 566 | cache[key] = result |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 567 | return result |
Raymond Hettinger | 7e0c581 | 2012-03-17 15:10:24 -0700 | [diff] [blame] | 568 | |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 569 | else: |
Raymond Hettinger | bc8e81d | 2012-03-17 00:24:09 -0700 | [diff] [blame] | 570 | |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 571 | def wrapper(*args, **kwds): |
| 572 | # Size limited caching that tracks accesses by recency |
| 573 | nonlocal root, hits, misses, full |
| 574 | key = make_key(args, kwds, typed) |
| 575 | with lock: |
| 576 | link = cache_get(key) |
| 577 | if link is not None: |
| 578 | # Move the link to the front of the circular queue |
| 579 | link_prev, link_next, _key, result = link |
| 580 | link_prev[NEXT] = link_next |
| 581 | link_next[PREV] = link_prev |
| 582 | last = root[PREV] |
| 583 | last[NEXT] = root[PREV] = link |
| 584 | link[PREV] = last |
| 585 | link[NEXT] = root |
Nick Coghlan | 234515a | 2010-11-30 06:19:46 +0000 | [diff] [blame] | 586 | hits += 1 |
Raymond Hettinger | 4b779b3 | 2011-10-15 23:50:42 -0700 | [diff] [blame] | 587 | return result |
Raymond Hettinger | d8080c0 | 2019-01-26 03:02:00 -0500 | [diff] [blame] | 588 | misses += 1 |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 589 | result = user_function(*args, **kwds) |
| 590 | with lock: |
| 591 | if key in cache: |
| 592 | # Getting here means that this same key was added to the |
| 593 | # cache while the lock was released. Since the link |
| 594 | # update is already done, we need only return the |
| 595 | # computed result and update the count of misses. |
| 596 | pass |
| 597 | elif full: |
| 598 | # Use the old root to store the new key and result. |
| 599 | oldroot = root |
| 600 | oldroot[KEY] = key |
| 601 | oldroot[RESULT] = result |
| 602 | # Empty the oldest link and make it the new root. |
| 603 | # Keep a reference to the old key and old result to |
| 604 | # prevent their ref counts from going to zero during the |
| 605 | # update. That will prevent potentially arbitrary object |
| 606 | # clean-up code (i.e. __del__) from running while we're |
| 607 | # still adjusting the links. |
| 608 | root = oldroot[NEXT] |
| 609 | oldkey = root[KEY] |
| 610 | oldresult = root[RESULT] |
| 611 | root[KEY] = root[RESULT] = None |
| 612 | # Now update the cache dictionary. |
| 613 | del cache[oldkey] |
| 614 | # Save the potentially reentrant cache[key] assignment |
| 615 | # for last, after the root and links have been put in |
| 616 | # a consistent state. |
| 617 | cache[key] = oldroot |
| 618 | else: |
| 619 | # Put result in a new link at the front of the queue. |
| 620 | last = root[PREV] |
| 621 | link = [last, root, key, result] |
| 622 | last[NEXT] = root[PREV] = cache[key] = link |
Raymond Hettinger | b2d4b3d | 2016-12-16 14:59:37 -0800 | [diff] [blame] | 623 | # Use the cache_len bound method instead of the len() function |
Raymond Hettinger | af56e0e | 2016-12-16 13:57:40 -0800 | [diff] [blame] | 624 | # which could potentially be wrapped in an lru_cache itself. |
Raymond Hettinger | b2d4b3d | 2016-12-16 14:59:37 -0800 | [diff] [blame] | 625 | full = (cache_len() >= maxsize) |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 626 | return result |
Raymond Hettinger | bc8e81d | 2012-03-17 00:24:09 -0700 | [diff] [blame] | 627 | |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 628 | def cache_info(): |
| 629 | """Report cache statistics""" |
| 630 | with lock: |
Raymond Hettinger | b2d4b3d | 2016-12-16 14:59:37 -0800 | [diff] [blame] | 631 | return _CacheInfo(hits, misses, maxsize, cache_len()) |
Raymond Hettinger | bc8e81d | 2012-03-17 00:24:09 -0700 | [diff] [blame] | 632 | |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 633 | def cache_clear(): |
| 634 | """Clear the cache and cache statistics""" |
| 635 | nonlocal hits, misses, full |
| 636 | with lock: |
| 637 | cache.clear() |
| 638 | root[:] = [root, root, None, None] |
| 639 | hits = misses = 0 |
| 640 | full = False |
Georg Brandl | 2e7346a | 2010-07-31 18:09:23 +0000 | [diff] [blame] | 641 | |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 642 | wrapper.cache_info = cache_info |
| 643 | wrapper.cache_clear = cache_clear |
Serhiy Storchaka | ce2295d | 2015-10-24 09:51:53 +0300 | [diff] [blame] | 644 | return wrapper |
Nick Coghlan | 234515a | 2010-11-30 06:19:46 +0000 | [diff] [blame] | 645 | |
Serhiy Storchaka | 46c5611 | 2015-05-24 21:53:49 +0300 | [diff] [blame] | 646 | try: |
| 647 | from _functools import _lru_cache_wrapper |
| 648 | except ImportError: |
| 649 | pass |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 650 | |
| 651 | |
| 652 | ################################################################################ |
| 653 | ### singledispatch() - single-dispatch generic function decorator |
| 654 | ################################################################################ |
| 655 | |
Łukasz Langa | 3720c77 | 2013-07-01 16:00:38 +0200 | [diff] [blame] | 656 | def _c3_merge(sequences): |
| 657 | """Merges MROs in *sequences* to a single MRO using the C3 algorithm. |
| 658 | |
| 659 | Adapted from http://www.python.org/download/releases/2.3/mro/. |
| 660 | |
| 661 | """ |
| 662 | result = [] |
| 663 | while True: |
| 664 | sequences = [s for s in sequences if s] # purge empty sequences |
| 665 | if not sequences: |
| 666 | return result |
| 667 | for s1 in sequences: # find merge candidates among seq heads |
| 668 | candidate = s1[0] |
| 669 | for s2 in sequences: |
| 670 | if candidate in s2[1:]: |
| 671 | candidate = None |
| 672 | break # reject the current head, it appears later |
| 673 | else: |
| 674 | break |
Yury Selivanov | 77a8cd6 | 2015-08-18 14:20:00 -0400 | [diff] [blame] | 675 | if candidate is None: |
Łukasz Langa | 3720c77 | 2013-07-01 16:00:38 +0200 | [diff] [blame] | 676 | raise RuntimeError("Inconsistent hierarchy") |
| 677 | result.append(candidate) |
| 678 | # remove the chosen candidate |
| 679 | for seq in sequences: |
| 680 | if seq[0] == candidate: |
| 681 | del seq[0] |
| 682 | |
| 683 | def _c3_mro(cls, abcs=None): |
| 684 | """Computes the method resolution order using extended C3 linearization. |
| 685 | |
| 686 | If no *abcs* are given, the algorithm works exactly like the built-in C3 |
| 687 | linearization used for method resolution. |
| 688 | |
| 689 | If given, *abcs* is a list of abstract base classes that should be inserted |
| 690 | into the resulting MRO. Unrelated ABCs are ignored and don't end up in the |
| 691 | result. The algorithm inserts ABCs where their functionality is introduced, |
| 692 | i.e. issubclass(cls, abc) returns True for the class itself but returns |
| 693 | False for all its direct base classes. Implicit ABCs for a given class |
| 694 | (either registered or inferred from the presence of a special method like |
| 695 | __len__) are inserted directly after the last ABC explicitly listed in the |
| 696 | MRO of said class. If two implicit ABCs end up next to each other in the |
| 697 | resulting MRO, their ordering depends on the order of types in *abcs*. |
| 698 | |
| 699 | """ |
| 700 | for i, base in enumerate(reversed(cls.__bases__)): |
| 701 | if hasattr(base, '__abstractmethods__'): |
| 702 | boundary = len(cls.__bases__) - i |
| 703 | break # Bases up to the last explicit ABC are considered first. |
| 704 | else: |
| 705 | boundary = 0 |
| 706 | abcs = list(abcs) if abcs else [] |
| 707 | explicit_bases = list(cls.__bases__[:boundary]) |
| 708 | abstract_bases = [] |
| 709 | other_bases = list(cls.__bases__[boundary:]) |
| 710 | for base in abcs: |
| 711 | if issubclass(cls, base) and not any( |
| 712 | issubclass(b, base) for b in cls.__bases__ |
| 713 | ): |
| 714 | # If *cls* is the class that introduces behaviour described by |
| 715 | # an ABC *base*, insert said ABC to its MRO. |
| 716 | abstract_bases.append(base) |
| 717 | for base in abstract_bases: |
| 718 | abcs.remove(base) |
| 719 | explicit_c3_mros = [_c3_mro(base, abcs=abcs) for base in explicit_bases] |
| 720 | abstract_c3_mros = [_c3_mro(base, abcs=abcs) for base in abstract_bases] |
| 721 | other_c3_mros = [_c3_mro(base, abcs=abcs) for base in other_bases] |
| 722 | return _c3_merge( |
| 723 | [[cls]] + |
| 724 | explicit_c3_mros + abstract_c3_mros + other_c3_mros + |
| 725 | [explicit_bases] + [abstract_bases] + [other_bases] |
| 726 | ) |
| 727 | |
| 728 | def _compose_mro(cls, types): |
| 729 | """Calculates the method resolution order for a given class *cls*. |
| 730 | |
| 731 | Includes relevant abstract base classes (with their respective bases) from |
| 732 | the *types* iterable. Uses a modified C3 linearization algorithm. |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 733 | |
| 734 | """ |
| 735 | bases = set(cls.__mro__) |
Łukasz Langa | 3720c77 | 2013-07-01 16:00:38 +0200 | [diff] [blame] | 736 | # Remove entries which are already present in the __mro__ or unrelated. |
| 737 | def is_related(typ): |
| 738 | return (typ not in bases and hasattr(typ, '__mro__') |
| 739 | and issubclass(cls, typ)) |
| 740 | types = [n for n in types if is_related(n)] |
| 741 | # Remove entries which are strict bases of other entries (they will end up |
| 742 | # in the MRO anyway. |
| 743 | def is_strict_base(typ): |
| 744 | for other in types: |
| 745 | if typ != other and typ in other.__mro__: |
| 746 | return True |
| 747 | return False |
| 748 | types = [n for n in types if not is_strict_base(n)] |
| 749 | # Subclasses of the ABCs in *types* which are also implemented by |
| 750 | # *cls* can be used to stabilize ABC ordering. |
| 751 | type_set = set(types) |
| 752 | mro = [] |
| 753 | for typ in types: |
| 754 | found = [] |
| 755 | for sub in typ.__subclasses__(): |
| 756 | if sub not in bases and issubclass(cls, sub): |
| 757 | found.append([s for s in sub.__mro__ if s in type_set]) |
| 758 | if not found: |
| 759 | mro.append(typ) |
| 760 | continue |
| 761 | # Favor subclasses with the biggest number of useful bases |
| 762 | found.sort(key=len, reverse=True) |
| 763 | for sub in found: |
| 764 | for subcls in sub: |
| 765 | if subcls not in mro: |
| 766 | mro.append(subcls) |
| 767 | return _c3_mro(cls, abcs=mro) |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 768 | |
| 769 | def _find_impl(cls, registry): |
Łukasz Langa | 3720c77 | 2013-07-01 16:00:38 +0200 | [diff] [blame] | 770 | """Returns the best matching implementation from *registry* for type *cls*. |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 771 | |
Łukasz Langa | 3720c77 | 2013-07-01 16:00:38 +0200 | [diff] [blame] | 772 | Where there is no registered implementation for a specific type, its method |
| 773 | resolution order is used to find a more generic implementation. |
| 774 | |
| 775 | Note: if *registry* does not contain an implementation for the base |
| 776 | *object* type, this function may return None. |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 777 | |
| 778 | """ |
| 779 | mro = _compose_mro(cls, registry.keys()) |
| 780 | match = None |
| 781 | for t in mro: |
| 782 | if match is not None: |
Łukasz Langa | 3720c77 | 2013-07-01 16:00:38 +0200 | [diff] [blame] | 783 | # If *match* is an implicit ABC but there is another unrelated, |
| 784 | # equally matching implicit ABC, refuse the temptation to guess. |
| 785 | if (t in registry and t not in cls.__mro__ |
| 786 | and match not in cls.__mro__ |
| 787 | and not issubclass(match, t)): |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 788 | raise RuntimeError("Ambiguous dispatch: {} or {}".format( |
| 789 | match, t)) |
| 790 | break |
| 791 | if t in registry: |
| 792 | match = t |
| 793 | return registry.get(match) |
| 794 | |
| 795 | def singledispatch(func): |
| 796 | """Single-dispatch generic function decorator. |
| 797 | |
| 798 | Transforms a function into a generic function, which can have different |
| 799 | behaviours depending upon the type of its first argument. The decorated |
| 800 | function acts as the default implementation, and additional |
Łukasz Langa | 3720c77 | 2013-07-01 16:00:38 +0200 | [diff] [blame] | 801 | implementations can be registered using the register() attribute of the |
| 802 | generic function. |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 803 | """ |
INADA Naoki | 9811e80 | 2017-09-30 16:13:02 +0900 | [diff] [blame] | 804 | # There are many programs that use functools without singledispatch, so we |
| 805 | # trade-off making singledispatch marginally slower for the benefit of |
| 806 | # making start-up of such applications slightly faster. |
| 807 | import types, weakref |
| 808 | |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 809 | registry = {} |
INADA Naoki | 9811e80 | 2017-09-30 16:13:02 +0900 | [diff] [blame] | 810 | dispatch_cache = weakref.WeakKeyDictionary() |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 811 | cache_token = None |
| 812 | |
Łukasz Langa | 3720c77 | 2013-07-01 16:00:38 +0200 | [diff] [blame] | 813 | def dispatch(cls): |
| 814 | """generic_func.dispatch(cls) -> <function implementation> |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 815 | |
| 816 | Runs the dispatch algorithm to return the best available implementation |
Łukasz Langa | 3720c77 | 2013-07-01 16:00:38 +0200 | [diff] [blame] | 817 | for the given *cls* registered on *generic_func*. |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 818 | |
| 819 | """ |
| 820 | nonlocal cache_token |
| 821 | if cache_token is not None: |
| 822 | current_token = get_cache_token() |
| 823 | if cache_token != current_token: |
| 824 | dispatch_cache.clear() |
| 825 | cache_token = current_token |
| 826 | try: |
Łukasz Langa | 3720c77 | 2013-07-01 16:00:38 +0200 | [diff] [blame] | 827 | impl = dispatch_cache[cls] |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 828 | except KeyError: |
| 829 | try: |
Łukasz Langa | 3720c77 | 2013-07-01 16:00:38 +0200 | [diff] [blame] | 830 | impl = registry[cls] |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 831 | except KeyError: |
Łukasz Langa | 3720c77 | 2013-07-01 16:00:38 +0200 | [diff] [blame] | 832 | impl = _find_impl(cls, registry) |
| 833 | dispatch_cache[cls] = impl |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 834 | return impl |
| 835 | |
Łukasz Langa | 3720c77 | 2013-07-01 16:00:38 +0200 | [diff] [blame] | 836 | def register(cls, func=None): |
| 837 | """generic_func.register(cls, func) -> func |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 838 | |
Łukasz Langa | 3720c77 | 2013-07-01 16:00:38 +0200 | [diff] [blame] | 839 | Registers a new implementation for the given *cls* on a *generic_func*. |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 840 | |
| 841 | """ |
| 842 | nonlocal cache_token |
| 843 | if func is None: |
Łukasz Langa | e569753 | 2017-12-11 13:56:31 -0800 | [diff] [blame] | 844 | if isinstance(cls, type): |
| 845 | return lambda f: register(cls, f) |
| 846 | ann = getattr(cls, '__annotations__', {}) |
| 847 | if not ann: |
| 848 | raise TypeError( |
| 849 | f"Invalid first argument to `register()`: {cls!r}. " |
| 850 | f"Use either `@register(some_class)` or plain `@register` " |
| 851 | f"on an annotated function." |
| 852 | ) |
| 853 | func = cls |
| 854 | |
| 855 | # only import typing if annotation parsing is necessary |
| 856 | from typing import get_type_hints |
| 857 | argname, cls = next(iter(get_type_hints(func).items())) |
Lysandros Nikolaou | d673810 | 2019-05-20 00:11:21 +0200 | [diff] [blame] | 858 | if not isinstance(cls, type): |
| 859 | raise TypeError( |
| 860 | f"Invalid annotation for {argname!r}. " |
| 861 | f"{cls!r} is not a class." |
| 862 | ) |
Łukasz Langa | 3720c77 | 2013-07-01 16:00:38 +0200 | [diff] [blame] | 863 | registry[cls] = func |
| 864 | if cache_token is None and hasattr(cls, '__abstractmethods__'): |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 865 | cache_token = get_cache_token() |
| 866 | dispatch_cache.clear() |
| 867 | return func |
| 868 | |
| 869 | def wrapper(*args, **kw): |
Dong-hee Na | 445f1b3 | 2018-07-10 16:26:36 +0900 | [diff] [blame] | 870 | if not args: |
| 871 | raise TypeError(f'{funcname} requires at least ' |
| 872 | '1 positional argument') |
| 873 | |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 874 | return dispatch(args[0].__class__)(*args, **kw) |
| 875 | |
Dong-hee Na | 445f1b3 | 2018-07-10 16:26:36 +0900 | [diff] [blame] | 876 | funcname = getattr(func, '__name__', 'singledispatch function') |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 877 | registry[object] = func |
| 878 | wrapper.register = register |
| 879 | wrapper.dispatch = dispatch |
INADA Naoki | 9811e80 | 2017-09-30 16:13:02 +0900 | [diff] [blame] | 880 | wrapper.registry = types.MappingProxyType(registry) |
Łukasz Langa | 6f69251 | 2013-06-05 12:20:24 +0200 | [diff] [blame] | 881 | wrapper._clear_cache = dispatch_cache.clear |
| 882 | update_wrapper(wrapper, func) |
| 883 | return wrapper |
Ethan Smith | c651275 | 2018-05-26 16:38:33 -0400 | [diff] [blame] | 884 | |
| 885 | |
| 886 | # Descriptor version |
| 887 | class singledispatchmethod: |
| 888 | """Single-dispatch generic method descriptor. |
| 889 | |
| 890 | Supports wrapping existing descriptors and handles non-descriptor |
| 891 | callables as instance methods. |
| 892 | """ |
| 893 | |
| 894 | def __init__(self, func): |
| 895 | if not callable(func) and not hasattr(func, "__get__"): |
| 896 | raise TypeError(f"{func!r} is not callable or a descriptor") |
| 897 | |
| 898 | self.dispatcher = singledispatch(func) |
| 899 | self.func = func |
| 900 | |
| 901 | def register(self, cls, method=None): |
| 902 | """generic_method.register(cls, func) -> func |
| 903 | |
| 904 | Registers a new implementation for the given *cls* on a *generic_method*. |
| 905 | """ |
| 906 | return self.dispatcher.register(cls, func=method) |
| 907 | |
| 908 | def __get__(self, obj, cls): |
| 909 | def _method(*args, **kwargs): |
| 910 | method = self.dispatcher.dispatch(args[0].__class__) |
| 911 | return method.__get__(obj, cls)(*args, **kwargs) |
| 912 | |
| 913 | _method.__isabstractmethod__ = self.__isabstractmethod__ |
| 914 | _method.register = self.register |
| 915 | update_wrapper(_method, self.func) |
| 916 | return _method |
| 917 | |
| 918 | @property |
| 919 | def __isabstractmethod__(self): |
| 920 | return getattr(self.func, '__isabstractmethod__', False) |
Carl Meyer | d658dea | 2018-08-28 01:11:56 -0600 | [diff] [blame] | 921 | |
| 922 | |
| 923 | ################################################################################ |
| 924 | ### cached_property() - computed once per instance, cached as attribute |
| 925 | ################################################################################ |
| 926 | |
| 927 | _NOT_FOUND = object() |
| 928 | |
| 929 | |
| 930 | class cached_property: |
| 931 | def __init__(self, func): |
| 932 | self.func = func |
| 933 | self.attrname = None |
| 934 | self.__doc__ = func.__doc__ |
| 935 | self.lock = RLock() |
| 936 | |
| 937 | def __set_name__(self, owner, name): |
| 938 | if self.attrname is None: |
| 939 | self.attrname = name |
| 940 | elif name != self.attrname: |
| 941 | raise TypeError( |
| 942 | "Cannot assign the same cached_property to two different names " |
| 943 | f"({self.attrname!r} and {name!r})." |
| 944 | ) |
| 945 | |
| 946 | def __get__(self, instance, owner): |
| 947 | if instance is None: |
| 948 | return self |
| 949 | if self.attrname is None: |
| 950 | raise TypeError( |
| 951 | "Cannot use cached_property instance without calling __set_name__ on it.") |
| 952 | try: |
| 953 | cache = instance.__dict__ |
| 954 | except AttributeError: # not all objects have __dict__ (e.g. class defines slots) |
| 955 | msg = ( |
| 956 | f"No '__dict__' attribute on {type(instance).__name__!r} " |
| 957 | f"instance to cache {self.attrname!r} property." |
| 958 | ) |
| 959 | raise TypeError(msg) from None |
| 960 | val = cache.get(self.attrname, _NOT_FOUND) |
| 961 | if val is _NOT_FOUND: |
| 962 | with self.lock: |
| 963 | # check if another thread filled cache while we awaited lock |
| 964 | val = cache.get(self.attrname, _NOT_FOUND) |
| 965 | if val is _NOT_FOUND: |
| 966 | val = self.func(instance) |
| 967 | try: |
| 968 | cache[self.attrname] = val |
| 969 | except TypeError: |
| 970 | msg = ( |
| 971 | f"The '__dict__' attribute on {type(instance).__name__!r} instance " |
| 972 | f"does not support item assignment for caching {self.attrname!r} property." |
| 973 | ) |
| 974 | raise TypeError(msg) from None |
| 975 | return val |