Source

pypy / pypy / objspace / std / typeobject.py

   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
from pypy.interpreter import gateway
from pypy.interpreter.baseobjspace import W_Root
from pypy.interpreter.error import OperationError, operationerrfmt
from pypy.interpreter.function import Function, StaticMethod
from pypy.interpreter.typedef import weakref_descr, GetSetProperty,\
     descr_get_dict
from pypy.interpreter.astcompiler.misc import mangle
from pypy.objspace.std.model import W_Object
from pypy.objspace.std.register_all import register_all
from pypy.objspace.std.stdtypedef import std_dict_descr, issubtypedef, Member
from pypy.objspace.std.stdtypedef import StdTypeDef

from rpython.rlib.jit import (promote, elidable_promote, we_are_jitted,
     promote_string, elidable, dont_look_inside, unroll_safe)
from rpython.rlib.objectmodel import current_object_addr_as_int, compute_hash
from rpython.rlib.rarithmetic import intmask, r_uint


class TypeCell(W_Root):
    def __init__(self, w_value=None):
        self.w_value = w_value


def unwrap_cell(space, w_value):
    if (space.config.objspace.std.withtypeversion and
            isinstance(w_value, TypeCell)):
        return w_value.w_value
    return w_value


class VersionTag(object):
    pass

class MethodCache(object):

    def __init__(self, space):
        assert space.config.objspace.std.withmethodcache
        SIZE = 1 << space.config.objspace.std.methodcachesizeexp
        self.versions = [None] * SIZE
        self.names = [None] * SIZE
        self.lookup_where = [(None, None)] * SIZE
        if space.config.objspace.std.withmethodcachecounter:
            self.hits = {}
            self.misses = {}

    def clear(self):
        None_None = (None, None)
        for i in range(len(self.versions)):
            self.versions[i] = None
        for i in range(len(self.names)):
            self.names[i] = None
        for i in range(len(self.lookup_where)):
            self.lookup_where[i] = None_None

# possible values of compares_by_identity_status
UNKNOWN = 0
COMPARES_BY_IDENTITY = 1
OVERRIDES_EQ_CMP_OR_HASH = 2

class W_TypeObject(W_Object):
    lazyloaders = {} # can be overridden by specific instances

    # the version_tag changes if the dict or the inheritance hierarchy changes
    # other changes to the type (e.g. the name) leave it unchanged
    _version_tag = None

    _immutable_fields_ = ["flag_heaptype",
                          "flag_cpytype",
                          "flag_abstract?",
                          'needsdel',
                          'weakrefable',
                          'hasdict',
                          'nslots',
                          'instancetypedef',
                          'terminator',
                          '_version_tag?',
                          'name?',
                          'mro_w?[*]',
                          ]

    # for config.objspace.std.getattributeshortcut
    # (False is a conservative default, fixed during real usage)
    uses_object_getattribute = False

    # for config.objspace.std.withidentitydict
    compares_by_identity_status = UNKNOWN

    # used to cache the type's __new__ function
    w_new_function = None

    @dont_look_inside
    def __init__(w_self, space, name, bases_w, dict_w,
                 overridetypedef=None):
        w_self.space = space
        w_self.name = name
        w_self.bases_w = bases_w
        w_self.dict_w = dict_w
        w_self.nslots = 0
        w_self.hasdict = False
        w_self.needsdel = False
        w_self.weakrefable = False
        w_self.w_doc = space.w_None
        w_self.weak_subclasses = []
        w_self.flag_heaptype = False
        w_self.flag_cpytype = False
        w_self.flag_abstract = False
        w_self.instancetypedef = overridetypedef

        if overridetypedef is not None:
            setup_builtin_type(w_self)
        else:
            setup_user_defined_type(w_self)
        w_self.w_same_layout_as = get_parent_layout(w_self)

        if space.config.objspace.std.withtypeversion:
            if not is_mro_purely_of_types(w_self.mro_w):
                pass
            else:
                # the _version_tag should change, whenever the content of
                # dict_w of any of the types in the mro changes, or if the mro
                # itself changes
                w_self._version_tag = VersionTag()
        if space.config.objspace.std.withmapdict:
            from pypy.objspace.std.mapdict import DictTerminator, NoDictTerminator
            if w_self.hasdict:
                w_self.terminator = DictTerminator(space, w_self)
            else:
                w_self.terminator = NoDictTerminator(space, w_self)

    def mutated(w_self, key):
        """
        The type is being mutated. key is either the string containing the
        specific attribute which is being deleted/set or None to indicate a
        generic mutation.
        """
        space = w_self.space
        assert w_self.is_heaptype() or w_self.is_cpytype()
        if (not space.config.objspace.std.withtypeversion and
            not space.config.objspace.std.getattributeshortcut and
            not space.config.objspace.std.withidentitydict and
            not space.config.objspace.std.newshortcut):
            return

        if space.config.objspace.std.getattributeshortcut:
            w_self.uses_object_getattribute = False
            # ^^^ conservative default, fixed during real usage

        if space.config.objspace.std.withidentitydict:
            if (key is None or key == '__eq__' or
                key == '__cmp__' or key == '__hash__'):
                w_self.compares_by_identity_status = UNKNOWN

        if space.config.objspace.std.newshortcut:
            w_self.w_new_function = None

        if (space.config.objspace.std.withtypeversion
            and w_self._version_tag is not None):
            w_self._version_tag = VersionTag()

        subclasses_w = w_self.get_subclasses()
        for w_subclass in subclasses_w:
            assert isinstance(w_subclass, W_TypeObject)
            w_subclass.mutated(key)

    def version_tag(w_self):
        if not we_are_jitted() or w_self.is_heaptype():
            return w_self._version_tag
        # prebuilt objects cannot get their version_tag changed
        return w_self._pure_version_tag()

    @elidable_promote()
    def _pure_version_tag(w_self):
        return w_self._version_tag

    def getattribute_if_not_from_object(w_self):
        """ this method returns the applevel __getattribute__ if that is not
        the one from object, in which case it returns None """
        from pypy.objspace.descroperation import object_getattribute
        if not we_are_jitted():
            shortcut = w_self.space.config.objspace.std.getattributeshortcut
            if not shortcut or not w_self.uses_object_getattribute:
                # slow path: look for a custom __getattribute__ on the class
                w_descr = w_self.lookup('__getattribute__')
                # if it was not actually overriden in the class, we remember this
                # fact for the next time.
                if w_descr is object_getattribute(w_self.space):
                    if shortcut:
                        w_self.uses_object_getattribute = True
                else:
                    return w_descr
            return None
        # in the JIT case, just use a lookup, because it is folded away
        # correctly using the version_tag
        w_descr = w_self.lookup('__getattribute__')
        if w_descr is not object_getattribute(w_self.space):
            return w_descr

    def has_object_getattribute(w_self):
        return w_self.getattribute_if_not_from_object() is None

    def compares_by_identity(w_self):
        from pypy.objspace.descroperation import object_hash, type_eq
        if not w_self.space.config.objspace.std.withidentitydict:
            return False # conservative
        #
        if w_self.compares_by_identity_status != UNKNOWN:
            # fast path
            return w_self.compares_by_identity_status == COMPARES_BY_IDENTITY
        #
        default_hash = object_hash(w_self.space)
        my_eq = w_self.lookup('__eq__')
        overrides_eq = (my_eq and my_eq is not type_eq(w_self.space))
        overrides_eq_cmp_or_hash = (overrides_eq or
                                    w_self.lookup('__cmp__') or
                                    w_self.lookup('__hash__') is not default_hash)
        if overrides_eq_cmp_or_hash:
            w_self.compares_by_identity_status = OVERRIDES_EQ_CMP_OR_HASH
        else:
            w_self.compares_by_identity_status = COMPARES_BY_IDENTITY
        return w_self.compares_by_identity_status == COMPARES_BY_IDENTITY

    def ready(w_self):
        for w_base in w_self.bases_w:
            if not isinstance(w_base, W_TypeObject):
                continue
            w_base.add_subclass(w_self)

    # compute a tuple that fully describes the instance layout
    def get_full_instance_layout(w_self):
        w_layout = w_self.w_same_layout_as or w_self
        return (w_layout, w_self.hasdict, w_self.needsdel, w_self.weakrefable)

    def compute_default_mro(w_self):
        return compute_C3_mro(w_self.space, w_self)

    def getdictvalue(w_self, space, attr):
        if space.config.objspace.std.withtypeversion:
            version_tag = w_self.version_tag()
            if version_tag is not None:
                return unwrap_cell(
                    space,
                    w_self._pure_getdictvalue_no_unwrapping(
                        space, version_tag, attr))
        w_value = w_self._getdictvalue_no_unwrapping(space, attr)
        return unwrap_cell(space, w_value)

    def _getdictvalue_no_unwrapping(w_self, space, attr):
        w_value = w_self.dict_w.get(attr, None)
        if w_self.lazyloaders and w_value is None:
            if attr in w_self.lazyloaders:
                # very clever next line: it forces the attr string
                # to be interned.
                space.new_interned_str(attr)
                loader = w_self.lazyloaders[attr]
                del w_self.lazyloaders[attr]
                w_value = loader()
                if w_value is not None:   # None means no such attribute
                    w_self.dict_w[attr] = w_value
                    return w_value
        return w_value

    @elidable
    def _pure_getdictvalue_no_unwrapping(w_self, space, version_tag, attr):
        return w_self._getdictvalue_no_unwrapping(space, attr)

    def setdictvalue(w_self, space, name, w_value):
        if not w_self.is_heaptype():
            msg = "can't set attributes on type object '%N'"
            raise operationerrfmt(space.w_TypeError, msg, w_self)
        if name == "__del__" and name not in w_self.dict_w:
            msg = ("a __del__ method added to an existing type will not be "
                   "called")
            space.warn(space.wrap(msg), space.w_RuntimeWarning)
        if space.config.objspace.std.withtypeversion:
            version_tag = w_self.version_tag()
            if version_tag is not None:
                w_curr = w_self._pure_getdictvalue_no_unwrapping(
                        space, version_tag, name)
                if w_curr is not None:
                    if isinstance(w_curr, TypeCell):
                        w_curr.w_value = w_value
                        return True
                    w_value = TypeCell(w_value)
        w_self.mutated(name)
        w_self.dict_w[name] = w_value
        return True

    def deldictvalue(w_self, space, key):
        if w_self.lazyloaders:
            w_self._cleanup_()    # force un-lazification
        if not w_self.is_heaptype():
            msg = "can't delete attributes on type object '%N'"
            raise operationerrfmt(space.w_TypeError, msg, w_self)
        try:
            del w_self.dict_w[key]
        except KeyError:
            return False
        else:
            w_self.mutated(key)
            return True

    def lookup(w_self, name):
        # note that this doesn't call __get__ on the result at all
        space = w_self.space
        if space.config.objspace.std.withmethodcache:
            return w_self.lookup_where_with_method_cache(name)[1]

        return w_self._lookup(name)

    def lookup_where(w_self, name):
        space = w_self.space
        if space.config.objspace.std.withmethodcache:
            return w_self.lookup_where_with_method_cache(name)

        return w_self._lookup_where(name)

    @unroll_safe
    def lookup_starting_at(w_self, w_starttype, name):
        space = w_self.space
        look = False
        for w_class in w_self.mro_w:
            if w_class is w_starttype:
                look = True
            elif look:
                w_value = w_class.getdictvalue(space, name)
                if w_value is not None:
                    return w_value
        return None

    @unroll_safe
    def _lookup(w_self, key):
        space = w_self.space
        for w_class in w_self.mro_w:
            w_value = w_class.getdictvalue(space, key)
            if w_value is not None:
                return w_value
        return None

    @unroll_safe
    def _lookup_where(w_self, key):
        # like lookup() but also returns the parent class in which the
        # attribute was found
        space = w_self.space
        for w_class in w_self.mro_w:
            w_value = w_class.getdictvalue(space, key)
            if w_value is not None:
                return w_class, w_value
        return None, None

    def _lookup_where_all_typeobjects(w_self, key):
        # like _lookup_where(), but when we know that w_self.mro_w only
        # contains W_TypeObjects.  (It differs from _lookup_where() mostly
        # from a JIT point of view: it cannot invoke arbitrary Python code.)
        space = w_self.space
        for w_class in w_self.mro_w:
            assert isinstance(w_class, W_TypeObject)
            w_value = w_class._getdictvalue_no_unwrapping(space, key)
            if w_value is not None:
                return w_class, w_value
        return None, None

    def lookup_where_with_method_cache(w_self, name):
        space = w_self.space
        promote(w_self)
        assert space.config.objspace.std.withmethodcache
        version_tag = promote(w_self.version_tag())
        if version_tag is None:
            tup = w_self._lookup_where(name)
            return tup
        name = promote_string(name)
        w_class, w_value = w_self._pure_lookup_where_with_method_cache(name, version_tag)
        return w_class, unwrap_cell(space, w_value)

    @elidable
    def _pure_lookup_where_with_method_cache(w_self, name, version_tag):
        space = w_self.space
        cache = space.fromcache(MethodCache)
        SHIFT2 = r_uint.BITS - space.config.objspace.std.methodcachesizeexp
        SHIFT1 = SHIFT2 - 5
        version_tag_as_int = current_object_addr_as_int(version_tag)
        # ^^^Note: if the version_tag object is moved by a moving GC, the
        # existing method cache entries won't be found any more; new
        # entries will be created based on the new address.  The
        # assumption is that the version_tag object won't keep moving all
        # the time - so using the fast current_object_addr_as_int() instead
        # of a slower solution like hash() is still a good trade-off.
        hash_name = compute_hash(name)
        product = intmask(version_tag_as_int * hash_name)
        method_hash = (r_uint(product) ^ (r_uint(product) << SHIFT1)) >> SHIFT2
        # ^^^Note2: we used to just take product>>SHIFT2, but on 64-bit
        # platforms SHIFT2 is really large, and we loose too much information
        # that way (as shown by failures of the tests that typically have
        # method names like 'f' who hash to a number that has only ~33 bits).
        cached_version_tag = cache.versions[method_hash]
        if cached_version_tag is version_tag:
            cached_name = cache.names[method_hash]
            if cached_name is name:
                tup = cache.lookup_where[method_hash]
                if space.config.objspace.std.withmethodcachecounter:
                    cache.hits[name] = cache.hits.get(name, 0) + 1
#                print "hit", w_self, name
                return tup
        tup = w_self._lookup_where_all_typeobjects(name)
        cache.versions[method_hash] = version_tag
        cache.names[method_hash] = name
        cache.lookup_where[method_hash] = tup
        if space.config.objspace.std.withmethodcachecounter:
            cache.misses[name] = cache.misses.get(name, 0) + 1
#        print "miss", w_self, name
        return tup

    def check_user_subclass(w_self, w_subtype):
        space = w_self.space
        if not isinstance(w_subtype, W_TypeObject):
            raise operationerrfmt(space.w_TypeError,
                "X is not a type object ('%T')",
                w_subtype)
        if not w_subtype.issubtype(w_self):
            raise operationerrfmt(space.w_TypeError,
                "%N.__new__(%N): %N is not a subtype of %N",
                w_self, w_subtype, w_subtype, w_self)
        if w_self.instancetypedef is not w_subtype.instancetypedef:
            raise operationerrfmt(space.w_TypeError,
                "%N.__new__(%N) is not safe, use %N.__new__()",
                w_self, w_subtype, w_subtype)
        return w_subtype

    def _cleanup_(w_self):
        "NOT_RPYTHON.  Forces the lazy attributes to be computed."
        if 'lazyloaders' in w_self.__dict__:
            for attr in w_self.lazyloaders.keys():
                w_self.getdictvalue(w_self.space, attr)
            del w_self.lazyloaders

    def getdict(w_self, space): # returning a dict-proxy!
        from pypy.objspace.std.dictproxyobject import DictProxyStrategy
        from pypy.objspace.std.dictmultiobject import W_DictMultiObject
        if w_self.lazyloaders:
            w_self._cleanup_()    # force un-lazification
        strategy = space.fromcache(DictProxyStrategy)
        storage = strategy.erase(w_self)
        return W_DictMultiObject(space, strategy, storage)

    def unwrap(w_self, space):
        from pypy.objspace.std.model import UnwrapError
        raise UnwrapError(w_self)

    def is_heaptype(w_self):
        return w_self.flag_heaptype

    def is_cpytype(w_self):
        return w_self.flag_cpytype

    def is_abstract(w_self):
        return w_self.flag_abstract

    def set_abstract(w_self, abstract):
        w_self.flag_abstract = bool(abstract)

    def issubtype(w_self, w_type):
        promote(w_self)
        promote(w_type)
        if w_self.space.config.objspace.std.withtypeversion and we_are_jitted():
            version_tag1 = w_self.version_tag()
            version_tag2 = w_type.version_tag()
            if version_tag1 is not None and version_tag2 is not None:
                res = _pure_issubtype(w_self, w_type, version_tag1, version_tag2)
                return res
        return _issubtype(w_self, w_type)

    def get_module(w_self):
        space = w_self.space
        if w_self.is_heaptype() and w_self.getdictvalue(space, '__module__') is not None:
            return w_self.getdictvalue(space, '__module__')
        else:
            # for non-heap types, CPython checks for a module.name in the
            # type name.  That's a hack, so we're allowed to use a different
            # hack...
            if ('__module__' in w_self.dict_w and
                space.isinstance_w(w_self.getdictvalue(space, '__module__'),
                                               space.w_str)):
                return w_self.getdictvalue(space, '__module__')
            return space.wrap('__builtin__')

    def get_module_type_name(w_self):
        space = w_self.space
        w_mod = w_self.get_module()
        if not space.isinstance_w(w_mod, space.w_str):
            mod = '__builtin__'
        else:
            mod = space.str_w(w_mod)
        if mod != '__builtin__':
            return '%s.%s' % (mod, w_self.name)
        else:
            return w_self.name

    def getname(w_self, space):
        name = w_self.name
        if name is None:
            name = '?'
        return name

    def add_subclass(w_self, w_subclass):
        space = w_self.space
        if not space.config.translation.rweakref:
            return    # no weakref support, don't keep track of subclasses
        import weakref
        assert isinstance(w_subclass, W_TypeObject)
        newref = weakref.ref(w_subclass)
        for i in range(len(w_self.weak_subclasses)):
            ref = w_self.weak_subclasses[i]
            if ref() is None:
                w_self.weak_subclasses[i] = newref
                return
        else:
            w_self.weak_subclasses.append(newref)

    def remove_subclass(w_self, w_subclass):
        space = w_self.space
        if not space.config.translation.rweakref:
            return    # no weakref support, don't keep track of subclasses
        for i in range(len(w_self.weak_subclasses)):
            ref = w_self.weak_subclasses[i]
            if ref() is w_subclass:
                del w_self.weak_subclasses[i]
                return

    def get_subclasses(w_self):
        space = w_self.space
        if not space.config.translation.rweakref:
            msg = ("this feature requires weakrefs, "
                   "which are not available in this build of PyPy")
            raise OperationError(space.w_RuntimeError,
                                 space.wrap(msg))
        subclasses_w = []
        for ref in w_self.weak_subclasses:
            w_ob = ref()
            if w_ob is not None:
                subclasses_w.append(w_ob)
        return subclasses_w

    # for now, weakref support for W_TypeObject is hard to get automatically
    _lifeline_ = None

    def getweakref(self):
        return self._lifeline_

    def setweakref(self, space, weakreflifeline):
        self._lifeline_ = weakreflifeline

    def delweakref(self):
        self._lifeline_ = None

def descr__new__(space, w_typetype, w_name, w_bases=None, w_dict=None):
    "This is used to create user-defined classes only."
    # XXX check types

    w_typetype = _precheck_for_new(space, w_typetype)

    # special case for type(x)
    if (space.is_w(space.type(w_typetype), space.w_type) and w_bases is None and
        w_dict is None):
        return space.type(w_name)
    else:
        return _create_new_type(space, w_typetype, w_name, w_bases, w_dict)


def _create_new_type(space, w_typetype, w_name, w_bases, w_dict):
    # this is in its own function because we want the special case 'type(x)'
    # above to be seen by the jit.
    from pypy.objspace.std.typeobject import W_TypeObject

    if w_bases is None or w_dict is None:
        raise OperationError(space.w_TypeError, space.wrap("type() takes 1 or 3 arguments"))

    bases_w = space.fixedview(w_bases)

    w_winner = w_typetype
    for base in bases_w:
        w_typ = space.type(base)
        if space.is_w(w_typ, space.w_classobj):
            continue # special-case old-style classes
        if space.is_true(space.issubtype(w_winner, w_typ)):
            continue
        if space.is_true(space.issubtype(w_typ, w_winner)):
            w_winner = w_typ
            continue
        raise OperationError(space.w_TypeError,
                             space.wrap("metaclass conflict: "
                                        "the metaclass of a derived class "
                                        "must be a (non-strict) subclass "
                                        "of the metaclasses of all its bases"))

    if not space.is_w(w_winner, w_typetype):
        newfunc = space.getattr(w_winner, space.wrap('__new__'))
        if not space.is_w(newfunc, space.getattr(space.w_type, space.wrap('__new__'))):
            return space.call_function(newfunc, w_winner, w_name, w_bases, w_dict)
        w_typetype = w_winner

    name = space.str_w(w_name)
    assert isinstance(name, str)
    dict_w = {}
    dictkeys_w = space.listview(w_dict)
    for w_key in dictkeys_w:
        key = space.str_w(w_key)
        dict_w[key] = space.getitem(w_dict, w_key)
    w_type = space.allocate_instance(W_TypeObject, w_typetype)
    W_TypeObject.__init__(w_type, space, name, bases_w or [space.w_object],
                          dict_w)
    w_type.ready()
    return w_type

def _precheck_for_new(space, w_type):
    from pypy.objspace.std.typeobject import W_TypeObject
    if not isinstance(w_type, W_TypeObject):
        raise operationerrfmt(space.w_TypeError, "X is not a type object (%T)",
                              w_type)
    return w_type

# ____________________________________________________________

def _check(space, w_type, w_msg=None):
    from pypy.objspace.std.typeobject import W_TypeObject
    if not isinstance(w_type, W_TypeObject):
        if w_msg is None:
            w_msg = space.wrap("descriptor is for 'type'")
        raise OperationError(space.w_TypeError, w_msg)
    return w_type


def descr_get__name__(space, w_type):
    w_type = _check(space, w_type)
    return space.wrap(w_type.name)

def descr_set__name__(space, w_type, w_value):
    w_type = _check(space, w_type)
    if not w_type.is_heaptype():
        raise operationerrfmt(space.w_TypeError,
                              "can't set %N.__name__", w_type)
    w_type.name = space.str_w(w_value)

def descr_get__mro__(space, w_type):
    w_type = _check(space, w_type)
    return space.newtuple(w_type.mro_w)

def descr_mro(space, w_type):
    """Return a type's method resolution order."""
    w_type = _check(space, w_type, space.wrap("expected type"))
    return space.newlist(w_type.compute_default_mro())

def descr_get__bases__(space, w_type):
    w_type = _check(space, w_type)
    return space.newtuple(w_type.bases_w)

def mro_subclasses(space, w_type, temp):
    from pypy.objspace.std.typeobject import W_TypeObject, compute_mro
    temp.append((w_type, w_type.mro_w))
    compute_mro(w_type)
    for w_sc in w_type.get_subclasses():
        assert isinstance(w_sc, W_TypeObject)
        mro_subclasses(space, w_sc, temp)

def descr_set__bases__(space, w_type, w_value):
    # this assumes all app-level type objects are W_TypeObject
    from pypy.objspace.std.typeobject import (W_TypeObject, get_parent_layout,
        check_and_find_best_base, is_mro_purely_of_types)

    w_type = _check(space, w_type)
    if not w_type.is_heaptype():
        raise operationerrfmt(space.w_TypeError,
                              "can't set %N.__bases__", w_type)
    if not space.isinstance_w(w_value, space.w_tuple):
        raise operationerrfmt(space.w_TypeError,
                              "can only assign tuple to %N.__bases__, not %T",
                              w_type, w_value)
    newbases_w = space.fixedview(w_value)
    if len(newbases_w) == 0:
        raise operationerrfmt(space.w_TypeError,
                    "can only assign non-empty tuple to %N.__bases__, not ()",
                              w_type)

    for w_newbase in newbases_w:
        if isinstance(w_newbase, W_TypeObject):
            if w_type in w_newbase.compute_default_mro():
                raise OperationError(space.w_TypeError,
                                     space.wrap("a __bases__ item causes"
                                                " an inheritance cycle"))

    w_oldbestbase = check_and_find_best_base(space, w_type.bases_w)
    w_newbestbase = check_and_find_best_base(space, newbases_w)
    oldlayout = w_oldbestbase.get_full_instance_layout()
    newlayout = w_newbestbase.get_full_instance_layout()

    if oldlayout != newlayout:
        msg = "__bases__ assignment: '%N' object layout differs from '%N'"
        raise operationerrfmt(space.w_TypeError, msg,
                              w_newbestbase, w_oldbestbase)

    # invalidate the version_tag of all the current subclasses
    w_type.mutated(None)

    # now we can go ahead and change 'w_type.bases_w'
    saved_bases_w = w_type.bases_w
    temp = []
    try:
        for w_oldbase in saved_bases_w:
            if isinstance(w_oldbase, W_TypeObject):
                w_oldbase.remove_subclass(w_type)
        w_type.bases_w = newbases_w
        for w_newbase in newbases_w:
            if isinstance(w_newbase, W_TypeObject):
                w_newbase.add_subclass(w_type)
        # try to recompute all MROs
        mro_subclasses(space, w_type, temp)
    except:
        for cls, old_mro in temp:
            cls.mro_w = old_mro
        w_type.bases_w = saved_bases_w
        raise
    if (space.config.objspace.std.withtypeversion and
        w_type.version_tag() is not None and
        not is_mro_purely_of_types(w_type.mro_w)):
        # Disable method cache if the hierarchy isn't pure.
        w_type._version_tag = None
        for w_subclass in w_type.get_subclasses():
            if isinstance(w_subclass, W_TypeObject):
                w_subclass._version_tag = None
    assert w_type.w_same_layout_as is get_parent_layout(w_type)  # invariant

def descr__base(space, w_type):
    from pypy.objspace.std.typeobject import find_best_base
    w_type = _check(space, w_type)
    return find_best_base(space, w_type.bases_w)

def descr__doc(space, w_type):
    if space.is_w(w_type, space.w_type):
        return space.wrap("""type(object) -> the object's type
type(name, bases, dict) -> a new type""")
    w_type = _check(space, w_type)
    if not w_type.is_heaptype():
        return w_type.w_doc
    w_result = w_type.getdictvalue(space, '__doc__')
    if w_result is None:
        return space.w_None
    else:
        return space.get(w_result, space.w_None, w_type)

def descr__flags(space, w_type):
    from copy_reg import _HEAPTYPE
    _CPYTYPE = 1 # used for non-heap types defined in C
    _ABSTRACT = 1 << 20
    #
    w_type = _check(space, w_type)
    flags = 0
    if w_type.flag_heaptype:
        flags |= _HEAPTYPE
    if w_type.flag_cpytype:
        flags |= _CPYTYPE
    if w_type.flag_abstract:
        flags |= _ABSTRACT
    return space.wrap(flags)

def descr_get__module(space, w_type):
    w_type = _check(space, w_type)
    return w_type.get_module()

def descr_set__module(space, w_type, w_value):
    w_type = _check(space, w_type)
    w_type.setdictvalue(space, '__module__', w_value)

def descr_get___abstractmethods__(space, w_type):
    w_type = _check(space, w_type)
    # type itself has an __abstractmethods__ descriptor (this). Don't return it
    if not space.is_w(w_type, space.w_type):
        w_result = w_type.getdictvalue(space, "__abstractmethods__")
        if w_result is not None:
            return w_result
    raise OperationError(space.w_AttributeError,
                         space.wrap("__abstractmethods__"))

def descr_set___abstractmethods__(space, w_type, w_new):
    w_type = _check(space, w_type)
    w_type.setdictvalue(space, "__abstractmethods__", w_new)
    w_type.set_abstract(space.is_true(w_new))

def descr_del___abstractmethods__(space, w_type):
    w_type = _check(space, w_type)
    if not w_type.deldictvalue(space, "__abstractmethods__"):
        raise OperationError(space.w_AttributeError,
                             space.wrap("__abstractmethods__"))
    w_type.set_abstract(False)

def descr___subclasses__(space, w_type):
    """Return the list of immediate subclasses."""
    w_type = _check(space, w_type)
    return space.newlist(w_type.get_subclasses())

# ____________________________________________________________

@gateway.unwrap_spec(w_obj=W_TypeObject, w_sub=W_TypeObject)
def type_issubtype(w_obj, space, w_sub):
    return space.newbool(w_sub.issubtype(w_obj))

@gateway.unwrap_spec(w_obj=W_TypeObject)
def type_isinstance(w_obj, space, w_inst):
    return space.newbool(space.type(w_inst).issubtype(w_obj))

type_typedef = StdTypeDef("type",
    __new__ = gateway.interp2app(descr__new__),
    __name__ = GetSetProperty(descr_get__name__, descr_set__name__),
    __bases__ = GetSetProperty(descr_get__bases__, descr_set__bases__),
    __base__ = GetSetProperty(descr__base),
    __mro__ = GetSetProperty(descr_get__mro__),
    __dict__ = GetSetProperty(descr_get_dict),
    __doc__ = GetSetProperty(descr__doc),
    mro = gateway.interp2app(descr_mro),
    __flags__ = GetSetProperty(descr__flags),
    __module__ = GetSetProperty(descr_get__module, descr_set__module),
    __abstractmethods__ = GetSetProperty(descr_get___abstractmethods__,
                                         descr_set___abstractmethods__,
                                         descr_del___abstractmethods__),
    __subclasses__ = gateway.interp2app(descr___subclasses__),
    __weakref__ = weakref_descr,
    __instancecheck__ = gateway.interp2app(type_isinstance),
    __subclasscheck__ = gateway.interp2app(type_issubtype),
    )
W_TypeObject.typedef = type_typedef

# ____________________________________________________________
# Initialization of type objects

def get_parent_layout(w_type):
    """Compute the most parent class of 'w_type' whose layout
       is the same as 'w_type', or None if all parents of 'w_type'
       have a different layout than 'w_type'.
    """
    w_starttype = w_type
    while len(w_type.bases_w) > 0:
        w_bestbase = find_best_base(w_type.space, w_type.bases_w)
        if w_type.instancetypedef is not w_bestbase.instancetypedef:
            break
        if w_type.nslots != w_bestbase.nslots:
            break
        w_type = w_bestbase
    if w_type is not w_starttype:
        return w_type
    else:
        return None

def issublayout(w_layout1, w_layout2):
    space = w_layout2.space
    while w_layout1 is not w_layout2:
        w_layout1 = find_best_base(space, w_layout1.bases_w)
        if w_layout1 is None:
            return False
        w_layout1 = w_layout1.w_same_layout_as or w_layout1
    return True

def find_best_base(space, bases_w):
    """The best base is one of the bases in the given list: the one
       whose layout a new type should use as a starting point.
    """
    w_bestbase = None
    for w_candidate in bases_w:
        if not isinstance(w_candidate, W_TypeObject):
            continue
        if w_bestbase is None:
            w_bestbase = w_candidate   # for now
            continue
        candtypedef = w_candidate.instancetypedef
        besttypedef = w_bestbase.instancetypedef
        if candtypedef is besttypedef:
            # two candidates with the same typedef are equivalent unless
            # one has extra slots over the other
            if w_candidate.nslots > w_bestbase.nslots:
                w_bestbase = w_candidate
        elif issubtypedef(candtypedef, besttypedef):
            w_bestbase = w_candidate
    return w_bestbase

def check_and_find_best_base(space, bases_w):
    """The best base is one of the bases in the given list: the one
       whose layout a new type should use as a starting point.
       This version checks that bases_w is an acceptable tuple of bases.
    """
    w_bestbase = find_best_base(space, bases_w)
    if w_bestbase is None:
        raise OperationError(space.w_TypeError,
                             space.wrap("a new-style class can't have "
                                        "only classic bases"))
    if not w_bestbase.instancetypedef.acceptable_as_base_class:
        raise operationerrfmt(space.w_TypeError,
                              "type '%N' is not an "
                              "acceptable base class",
                              w_bestbase)

    # check that all other bases' layouts are superclasses of the bestbase
    w_bestlayout = w_bestbase.w_same_layout_as or w_bestbase
    for w_base in bases_w:
        if isinstance(w_base, W_TypeObject):
            w_layout = w_base.w_same_layout_as or w_base
            if not issublayout(w_bestlayout, w_layout):
                raise OperationError(space.w_TypeError,
                                     space.wrap("instance layout conflicts in "
                                                "multiple inheritance"))
    return w_bestbase

def copy_flags_from_bases(w_self, w_bestbase):
    hasoldstylebase = False
    for w_base in w_self.bases_w:
        if not isinstance(w_base, W_TypeObject):
            hasoldstylebase = True
            continue
        w_self.hasdict = w_self.hasdict or w_base.hasdict
        w_self.needsdel = w_self.needsdel or w_base.needsdel
        w_self.weakrefable = w_self.weakrefable or w_base.weakrefable
    w_self.nslots = w_bestbase.nslots
    return hasoldstylebase

def create_all_slots(w_self, hasoldstylebase):
    space = w_self.space
    dict_w = w_self.dict_w
    if '__slots__' not in dict_w:
        wantdict = True
        wantweakref = True
    else:
        wantdict = False
        wantweakref = False
        w_slots = dict_w['__slots__']
        if (space.isinstance_w(w_slots, space.w_str) or
            space.isinstance_w(w_slots, space.w_unicode)):
            slot_names_w = [w_slots]
        else:
            slot_names_w = space.unpackiterable(w_slots)
        for w_slot_name in slot_names_w:
            slot_name = space.str_w(w_slot_name)
            if slot_name == '__dict__':
                if wantdict or w_self.hasdict:
                    raise OperationError(space.w_TypeError,
                            space.wrap("__dict__ slot disallowed: "
                                       "we already got one"))
                wantdict = True
            elif slot_name == '__weakref__':
                if wantweakref or w_self.weakrefable:
                    raise OperationError(space.w_TypeError,
                            space.wrap("__weakref__ slot disallowed: "
                                       "we already got one"))
                wantweakref = True
            else:
                create_slot(w_self, slot_name)
    wantdict = wantdict or hasoldstylebase
    if wantdict:
        create_dict_slot(w_self)
    if wantweakref:
        create_weakref_slot(w_self)
    if '__del__' in dict_w:
        w_self.needsdel = True

def create_slot(w_self, slot_name):
    space = w_self.space
    if not valid_slot_name(slot_name):
        raise OperationError(space.w_TypeError,
                             space.wrap('__slots__ must be identifiers'))
    # create member
    slot_name = mangle(slot_name, w_self.name)
    if slot_name not in w_self.dict_w:
        # Force interning of slot names.
        slot_name = space.str_w(space.new_interned_str(slot_name))
        # in cpython it is ignored less, but we probably don't care
        member = Member(w_self.nslots, slot_name, w_self)
        w_self.dict_w[slot_name] = space.wrap(member)
        w_self.nslots += 1

def create_dict_slot(w_self):
    if not w_self.hasdict:
        w_self.dict_w.setdefault('__dict__',
                                 w_self.space.wrap(std_dict_descr))
        w_self.hasdict = True

def create_weakref_slot(w_self):
    if not w_self.weakrefable:
        w_self.dict_w.setdefault('__weakref__',
                                 w_self.space.wrap(weakref_descr))
        w_self.weakrefable = True

def valid_slot_name(slot_name):
    if len(slot_name) == 0 or slot_name[0].isdigit():
        return False
    for c in slot_name:
        if not c.isalnum() and c != '_':
            return False
    return True

def setup_user_defined_type(w_self):
    if len(w_self.bases_w) == 0:
        w_self.bases_w = [w_self.space.w_object]
    w_bestbase = check_and_find_best_base(w_self.space, w_self.bases_w)
    w_self.instancetypedef = w_bestbase.instancetypedef
    w_self.flag_heaptype = True
    for w_base in w_self.bases_w:
        if not isinstance(w_base, W_TypeObject):
            continue
        w_self.flag_cpytype |= w_base.flag_cpytype
        w_self.flag_abstract |= w_base.flag_abstract

    hasoldstylebase = copy_flags_from_bases(w_self, w_bestbase)
    create_all_slots(w_self, hasoldstylebase)

    ensure_common_attributes(w_self)

def setup_builtin_type(w_self):
    w_self.hasdict = w_self.instancetypedef.hasdict
    w_self.weakrefable = w_self.instancetypedef.weakrefable
    w_self.w_doc = w_self.space.wrap(w_self.instancetypedef.doc)
    ensure_common_attributes(w_self)

def ensure_common_attributes(w_self):
    ensure_static_new(w_self)
    w_self.dict_w.setdefault('__doc__', w_self.w_doc)
    if w_self.is_heaptype():
        ensure_module_attr(w_self)
    w_self.mro_w = []      # temporarily
    compute_mro(w_self)

def ensure_static_new(w_self):
    # special-case __new__, as in CPython:
    # if it is a Function, turn it into a static method
    if '__new__' in w_self.dict_w:
        w_new = w_self.dict_w['__new__']
        if isinstance(w_new, Function):
            w_self.dict_w['__new__'] = StaticMethod(w_new)

def ensure_module_attr(w_self):
    # initialize __module__ in the dict (user-defined types only)
    if '__module__' not in w_self.dict_w:
        space = w_self.space
        caller = space.getexecutioncontext().gettopframe_nohidden()
        if caller is not None:
            w_globals = caller.w_globals
            w_name = space.finditem(w_globals, space.wrap('__name__'))
            if w_name is not None:
                w_self.dict_w['__module__'] = w_name

def compute_mro(w_self):
    if w_self.is_heaptype():
        space = w_self.space
        w_metaclass = space.type(w_self)
        w_where, w_mro_func = space.lookup_in_type_where(w_metaclass, 'mro')
        if w_mro_func is not None and not space.is_w(w_where, space.w_type):
            w_mro_meth = space.get(w_mro_func, w_self)
            w_mro = space.call_function(w_mro_meth)
            mro_w = space.fixedview(w_mro)
            w_self.mro_w = validate_custom_mro(space, mro_w)
            return    # done
    w_self.mro_w = w_self.compute_default_mro()[:]

def validate_custom_mro(space, mro_w):
    # do some checking here.  Note that unlike CPython, strange MROs
    # cannot really segfault PyPy.  At a minimum, we check that all
    # the elements in the mro seem to be (old- or new-style) classes.
    for w_class in mro_w:
        if not space.abstract_isclass_w(w_class):
            raise OperationError(space.w_TypeError,
                                 space.wrap("mro() returned a non-class"))
    return mro_w

def is_mro_purely_of_types(mro_w):
    for w_class in mro_w:
        if not isinstance(w_class, W_TypeObject):
            return False
    return True

# ____________________________________________________________

def call__Type(space, w_type, __args__):
    promote(w_type)
    # invoke the __new__ of the type
    if not we_are_jitted():
        # note that the annotator will figure out that w_type.w_new_function
        # can only be None if the newshortcut config option is not set
        w_newfunc = w_type.w_new_function
    else:
        # for the JIT it is better to take the slow path because normal lookup
        # is nicely optimized, but the w_type.w_new_function attribute is not
        # known to the JIT
        w_newfunc = None
    if w_newfunc is None:
        w_newtype, w_newdescr = w_type.lookup_where('__new__')
        w_newfunc = space.get(w_newdescr, w_type)
        if (space.config.objspace.std.newshortcut and
            not we_are_jitted() and
            isinstance(w_newtype, W_TypeObject)):
            w_type.w_new_function = w_newfunc
    w_newobject = space.call_obj_args(w_newfunc, w_type, __args__)
    call_init = space.isinstance_w(w_newobject, w_type)

    # maybe invoke the __init__ of the type
    if (call_init and not (space.is_w(w_type, space.w_type) and
        not __args__.keywords and len(__args__.arguments_w) == 1)):
        w_descr = space.lookup(w_newobject, '__init__')
        w_result = space.get_and_call_args(w_descr, w_newobject, __args__)
        if not space.is_w(w_result, space.w_None):
            raise OperationError(space.w_TypeError,
                                 space.wrap("__init__() should return None"))
    return w_newobject

def _issubtype(w_sub, w_type):
    return w_type in w_sub.mro_w

@elidable_promote()
def _pure_issubtype(w_sub, w_type, version_tag1, version_tag2):
    return _issubtype(w_sub, w_type)

def repr__Type(space, w_obj):
    w_mod = w_obj.get_module()
    if not space.isinstance_w(w_mod, space.w_str):
        mod = None
    else:
        mod = space.str_w(w_mod)
    if not w_obj.is_heaptype():
        kind = 'type'
    else:
        kind = 'class'
    if mod is not None and mod != '__builtin__':
        return space.wrap("<%s '%s.%s'>" % (kind, mod, w_obj.name))
    else:
        return space.wrap("<%s '%s'>" % (kind, w_obj.name))

def getattr__Type_ANY(space, w_type, w_name):
    name = space.str_w(w_name)
    w_descr = space.lookup(w_type, name)
    if w_descr is not None:
        if space.is_data_descr(w_descr):
            w_get = space.lookup(w_descr, "__get__")
            if w_get is not None:
                return space.get_and_call_function(w_get, w_descr, w_type,
                                                   space.type(w_type))
    w_value = w_type.lookup(name)
    if w_value is not None:
        # __get__(None, type): turns e.g. functions into unbound methods
        return space.get(w_value, space.w_None, w_type)
    if w_descr is not None:
        return space.get(w_descr, w_type)
    raise operationerrfmt(space.w_AttributeError,
                          "type object '%N' has no attribute %R",
                          w_type, w_name)

def eq__Type_Type(space, w_self, w_other):
    return space.is_(w_self, w_other)


# ____________________________________________________________


abstract_mro = gateway.applevel("""
    def abstract_mro(klass):
        # abstract/classic mro
        mro = []
        stack = [klass]
        while stack:
            klass = stack.pop()
            if klass not in mro:
                mro.append(klass)
                if not isinstance(klass.__bases__, tuple):
                    raise TypeError, '__bases__ must be a tuple'
                stack += klass.__bases__[::-1]
        return mro
""", filename=__file__).interphook("abstract_mro")

def get_mro(space, klass):
    if isinstance(klass, W_TypeObject):
        return list(klass.mro_w)
    else:
        return space.unpackiterable(abstract_mro(space, klass))


def compute_C3_mro(space, cls):
    order = []
    orderlists = [get_mro(space, base) for base in cls.bases_w]
    orderlists.append([cls] + cls.bases_w)
    while orderlists:
        for candidatelist in orderlists:
            candidate = candidatelist[0]
            if mro_blockinglist(candidate, orderlists) is None:
                break    # good candidate
        else:
            return mro_error(space, orderlists)  # no candidate found
        assert candidate not in order
        order.append(candidate)
        for i in range(len(orderlists) - 1, -1, -1):
            if orderlists[i][0] is candidate:
                del orderlists[i][0]
                if len(orderlists[i]) == 0:
                    del orderlists[i]
    return order


def mro_blockinglist(candidate, orderlists):
    for lst in orderlists:
        if candidate in lst[1:]:
            return lst
    return None # good candidate

def mro_error(space, orderlists):
    cycle = []
    candidate = orderlists[-1][0]
    if candidate in orderlists[-1][1:]:
        # explicit error message for this specific case
        raise operationerrfmt(space.w_TypeError, "duplicate base class '%N'",
                              candidate)
    while candidate not in cycle:
        cycle.append(candidate)
        nextblockinglist = mro_blockinglist(candidate, orderlists)
        candidate = nextblockinglist[0]
    del cycle[:cycle.index(candidate)]
    cycle.append(candidate)
    cycle.reverse()
    names = [cls.getname(space) for cls in cycle]
    raise OperationError(space.w_TypeError,
        space.wrap("cycle among base classes: " + ' < '.join(names)))

# ____________________________________________________________

register_all(vars())
Tip: Filter by directory path e.g. /media app.js to search for public/media/app.js.
Tip: Use camelCasing e.g. ProjME to search for ProjectModifiedEvent.java.
Tip: Filter by extension type e.g. /repo .js to search for all .js files in the /repo directory.
Tip: Separate your search with spaces e.g. /ssh pom.xml to search for src/ssh/pom.xml.
Tip: Use ↑ and ↓ arrow keys to navigate and return to view the file.
Tip: You can also navigate files with Ctrl+j (next) and Ctrl+k (previous) and view the file with Ctrl+o.
Tip: You can also navigate files with Alt+j (next) and Alt+k (previous) and view the file with Alt+o.