src/bindings/python/bt2/bt2/field.py

   1 # The MIT License (MIT)
   2 #
   3 # Copyright (c) 2017 Philippe Proulx <pproulx@efficios.com>
   4 #
   5 # Permission is hereby granted, free of charge, to any person obtaining a copy
   6 # of this software and associated documentation files (the "Software"), to deal
   7 # in the Software without restriction, including without limitation the rights
   8 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   9 # copies of the Software, and to permit persons to whom the Software is
  10 # furnished to do so, subject to the following conditions:
  11 #
  12 # The above copyright notice and this permission notice shall be included in
  13 # all copies or substantial portions of the Software.
  14 #
  15 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  18 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  21 # THE SOFTWARE.
  22
  23 from bt2 import native_bt, object, utils
  24 from bt2 import field_class as bt2_field_class
  25 import collections.abc
  26 import functools
  27 import numbers
  28 import math
  29
  30
  31 def _create_field_from_ptr_template(
  32     object_map, ptr, owner_ptr, owner_get_ref, owner_put_ref
  33 ):
  34
  35     field_class_ptr = native_bt.field_borrow_class_const(ptr)
  36     typeid = native_bt.field_class_get_type(field_class_ptr)
  37     field = object_map[typeid]._create_from_ptr_and_get_ref(
  38         ptr, owner_ptr, owner_get_ref, owner_put_ref
  39     )
  40     return field
  41
  42
  43 def _create_field_from_ptr(ptr, owner_ptr, owner_get_ref, owner_put_ref):
  44     return _create_field_from_ptr_template(
  45         _TYPE_ID_TO_OBJ, ptr, owner_ptr, owner_get_ref, owner_put_ref
  46     )
  47
  48
  49 def _create_field_from_const_ptr(ptr, owner_ptr, owner_get_ref, owner_put_ref):
  50     return _create_field_from_ptr_template(
  51         _TYPE_ID_TO_CONST_OBJ, ptr, owner_ptr, owner_get_ref, owner_put_ref
  52     )
  53
  54
  55 # Get the "effective" field of `field`.  If `field` is a variant, return
  56 # the currently selected field.  If `field` is an option, return the
  57 # content field.  If `field` is of any other type, return `field`
  58 # directly.
  59
  60
  61 def _get_leaf_field(field):
  62     if isinstance(field, _VariantFieldConst):
  63         return _get_leaf_field(field.selected_option)
  64
  65     if isinstance(field, _OptionFieldConst):
  66         return _get_leaf_field(field.field)
  67
  68     return field
  69
  70
  71 class _FieldConst(object._UniqueObject):
  72     _create_field_from_ptr = staticmethod(_create_field_from_const_ptr)
  73     _create_field_class_from_ptr_and_get_ref = staticmethod(
  74         bt2_field_class._create_field_class_from_const_ptr_and_get_ref
  75     )
  76     _borrow_class_ptr = staticmethod(native_bt.field_borrow_class_const)
  77
  78     def __eq__(self, other):
  79         other = _get_leaf_field(other)
  80         return self._spec_eq(other)
  81
  82     @property
  83     def cls(self):
  84         field_class_ptr = self._borrow_class_ptr(self._ptr)
  85         assert field_class_ptr is not None
  86         return self._create_field_class_from_ptr_and_get_ref(field_class_ptr)
  87
  88     def _repr(self):
  89         raise NotImplementedError
  90
  91     def __repr__(self):
  92         return self._repr()
  93
  94
  95 class _Field(_FieldConst):
  96     _create_field_from_ptr = staticmethod(_create_field_from_ptr)
  97     _create_field_class_from_ptr_and_get_ref = staticmethod(
  98         bt2_field_class._create_field_class_from_ptr_and_get_ref
  99     )
 100     _borrow_class_ptr = staticmethod(native_bt.field_borrow_class)
 101
 102
 103 class _BitArrayFieldConst(_FieldConst):
 104     _NAME = 'Const bit array'
 105
 106     @property
 107     def value_as_integer(self):
 108         return native_bt.field_bit_array_get_value_as_integer(self._ptr)
 109
 110     def _spec_eq(self, other):
 111         if type(other) is not type(self):
 112             return False
 113
 114         return self.value_as_integer == other.value_as_integer
 115
 116     def _repr(self):
 117         return repr(self.value_as_integer)
 118
 119     def __str__(self):
 120         return str(self.value_as_integer)
 121
 122     def __len__(self):
 123         return self.cls.length
 124
 125
 126 class _BitArrayField(_BitArrayFieldConst, _Field):
 127     _NAME = 'Bit array'
 128
 129     def _value_as_integer(self, value):
 130         utils._check_uint64(value)
 131         native_bt.field_bit_array_set_value_as_integer(self._ptr, value)
 132
 133     value_as_integer = property(
 134         fget=_BitArrayFieldConst.value_as_integer.fget, fset=_value_as_integer
 135     )
 136
 137
 138 @functools.total_ordering
 139 class _NumericFieldConst(_FieldConst):
 140     @staticmethod
 141     def _extract_value(other):
 142         if isinstance(other, _BoolFieldConst) or isinstance(other, bool):
 143             return bool(other)
 144
 145         if isinstance(other, numbers.Integral):
 146             return int(other)
 147
 148         if isinstance(other, numbers.Real):
 149             return float(other)
 150
 151         if isinstance(other, numbers.Complex):
 152             return complex(other)
 153
 154         raise TypeError(
 155             "'{}' object is not a number object".format(other.__class__.__name__)
 156         )
 157
 158     def __int__(self):
 159         return int(self._value)
 160
 161     def __float__(self):
 162         return float(self._value)
 163
 164     def _repr(self):
 165         return repr(self._value)
 166
 167     def __lt__(self, other):
 168         if not isinstance(other, numbers.Number):
 169             raise TypeError(
 170                 'unorderable types: {}() < {}()'.format(
 171                     self.__class__.__name__, other.__class__.__name__
 172                 )
 173             )
 174
 175         return self._value < self._extract_value(other)
 176
 177     def _spec_eq(self, other):
 178         try:
 179             return self._value == self._extract_value(other)
 180         except Exception:
 181             return False
 182
 183     def __hash__(self):
 184         return hash(self._value)
 185
 186     def __rmod__(self, other):
 187         return self._extract_value(other) % self._value
 188
 189     def __mod__(self, other):
 190         return self._value % self._extract_value(other)
 191
 192     def __rfloordiv__(self, other):
 193         return self._extract_value(other) // self._value
 194
 195     def __floordiv__(self, other):
 196         return self._value // self._extract_value(other)
 197
 198     def __round__(self, ndigits=None):
 199         if ndigits is None:
 200             return round(self._value)
 201         else:
 202             return round(self._value, ndigits)
 203
 204     def __ceil__(self):
 205         return math.ceil(self._value)
 206
 207     def __floor__(self):
 208         return math.floor(self._value)
 209
 210     def __trunc__(self):
 211         return int(self._value)
 212
 213     def __abs__(self):
 214         return abs(self._value)
 215
 216     def __add__(self, other):
 217         return self._value + self._extract_value(other)
 218
 219     def __radd__(self, other):
 220         return self.__add__(other)
 221
 222     def __neg__(self):
 223         return -self._value
 224
 225     def __pos__(self):
 226         return +self._value
 227
 228     def __mul__(self, other):
 229         return self._value * self._extract_value(other)
 230
 231     def __rmul__(self, other):
 232         return self.__mul__(other)
 233
 234     def __truediv__(self, other):
 235         return self._value / self._extract_value(other)
 236
 237     def __rtruediv__(self, other):
 238         return self._extract_value(other) / self._value
 239
 240     def __pow__(self, exponent):
 241         return self._value ** self._extract_value(exponent)
 242
 243     def __rpow__(self, base):
 244         return self._extract_value(base) ** self._value
 245
 246
 247 class _NumericField(_NumericFieldConst, _Field):
 248     def __hash__(self):
 249         # Non const field are not hashable as their value may be modified
 250         # without changing the underlying Python object.
 251         raise TypeError('unhashable type: \'{}\''.format(self._NAME))
 252
 253
 254 class _IntegralFieldConst(_NumericFieldConst, numbers.Integral):
 255     def __lshift__(self, other):
 256         return self._value << self._extract_value(other)
 257
 258     def __rlshift__(self, other):
 259         return self._extract_value(other) << self._value
 260
 261     def __rshift__(self, other):
 262         return self._value >> self._extract_value(other)
 263
 264     def __rrshift__(self, other):
 265         return self._extract_value(other) >> self._value
 266
 267     def __and__(self, other):
 268         return self._value & self._extract_value(other)
 269
 270     def __rand__(self, other):
 271         return self._extract_value(other) & self._value
 272
 273     def __xor__(self, other):
 274         return self._value ^ self._extract_value(other)
 275
 276     def __rxor__(self, other):
 277         return self._extract_value(other) ^ self._value
 278
 279     def __or__(self, other):
 280         return self._value | self._extract_value(other)
 281
 282     def __ror__(self, other):
 283         return self._extract_value(other) | self._value
 284
 285     def __invert__(self):
 286         return ~self._value
 287
 288
 289 class _IntegralField(_IntegralFieldConst, _NumericField):
 290     pass
 291
 292
 293 class _BoolFieldConst(_IntegralFieldConst, _FieldConst):
 294     _NAME = 'Const boolean'
 295
 296     def __bool__(self):
 297         return self._value
 298
 299     @classmethod
 300     def _value_to_bool(cls, value):
 301         if isinstance(value, _BoolFieldConst):
 302             value = value._value
 303
 304         if not isinstance(value, bool):
 305             raise TypeError(
 306                 "'{}' object is not a 'bool', '_BoolFieldConst', or '_BoolField' object".format(
 307                     value.__class__
 308                 )
 309             )
 310
 311         return value
 312
 313     @property
 314     def _value(self):
 315         return bool(native_bt.field_bool_get_value(self._ptr))
 316
 317
 318 class _BoolField(_BoolFieldConst, _IntegralField, _Field):
 319     _NAME = 'Boolean'
 320
 321     def _set_value(self, value):
 322         value = self._value_to_bool(value)
 323         native_bt.field_bool_set_value(self._ptr, value)
 324
 325     value = property(fset=_set_value)
 326
 327
 328 class _IntegerFieldConst(_IntegralFieldConst, _FieldConst):
 329     pass
 330
 331
 332 class _IntegerField(_IntegerFieldConst, _IntegralField, _Field):
 333     def _check_range(self, value):
 334         if not (value >= self._lower_bound and value <= self._upper_bound):
 335             raise ValueError(
 336                 "Value {} is outside valid range [{}, {}]".format(
 337                     value, self._lower_bound, self._upper_bound
 338                 )
 339             )
 340
 341
 342 class _UnsignedIntegerFieldConst(_IntegerFieldConst, _FieldConst):
 343     _NAME = 'Const unsigned integer'
 344
 345     @classmethod
 346     def _value_to_int(cls, value):
 347         if not isinstance(value, numbers.Integral):
 348             raise TypeError('expecting an integral number object')
 349
 350         return int(value)
 351
 352     @property
 353     def _value(self):
 354         return native_bt.field_integer_unsigned_get_value(self._ptr)
 355
 356
 357 class _UnsignedIntegerField(_UnsignedIntegerFieldConst, _IntegerField, _Field):
 358     _NAME = 'Unsigned integer'
 359
 360     def _set_value(self, value):
 361         value = self._value_to_int(value)
 362
 363         self._check_range(value)
 364
 365         native_bt.field_integer_unsigned_set_value(self._ptr, value)
 366
 367     value = property(fset=_set_value)
 368
 369     @property
 370     def _lower_bound(self):
 371         return 0
 372
 373     @property
 374     def _upper_bound(self):
 375         return (2 ** self.cls.field_value_range) - 1
 376
 377
 378 class _SignedIntegerFieldConst(_IntegerFieldConst, _FieldConst):
 379     _NAME = 'Const signed integer'
 380
 381     @classmethod
 382     def _value_to_int(cls, value):
 383         if not isinstance(value, numbers.Integral):
 384             raise TypeError('expecting an integral number object')
 385
 386         return int(value)
 387
 388     @property
 389     def _value(self):
 390         return native_bt.field_integer_signed_get_value(self._ptr)
 391
 392
 393 class _SignedIntegerField(_SignedIntegerFieldConst, _IntegerField, _Field):
 394     _NAME = 'Signed integer'
 395
 396     def _set_value(self, value):
 397         value = self._value_to_int(value)
 398
 399         self._check_range(value)
 400
 401         native_bt.field_integer_signed_set_value(self._ptr, value)
 402
 403     value = property(fset=_set_value)
 404
 405     @property
 406     def _lower_bound(self):
 407         return -1 * (2 ** (self.cls.field_value_range - 1))
 408
 409     @property
 410     def _upper_bound(self):
 411         return (2 ** (self.cls.field_value_range - 1)) - 1
 412
 413
 414 class _RealFieldConst(_NumericFieldConst, numbers.Real):
 415     _NAME = 'Const real'
 416
 417     @classmethod
 418     def _value_to_float(cls, value):
 419         if not isinstance(value, numbers.Real):
 420             raise TypeError("expecting a real number object")
 421
 422         return float(value)
 423
 424     @property
 425     def _value(self):
 426         return native_bt.field_real_get_value(self._ptr)
 427
 428
 429 class _RealField(_RealFieldConst, _NumericField):
 430     _NAME = 'Real'
 431
 432     def _set_value(self, value):
 433         value = self._value_to_float(value)
 434         native_bt.field_real_set_value(self._ptr, value)
 435
 436     value = property(fset=_set_value)
 437
 438
 439 class _EnumerationFieldConst(_IntegerFieldConst):
 440     def _repr(self):
 441         return '{} ({})'.format(self._value, ', '.join(self.labels))
 442
 443     @property
 444     def labels(self):
 445         status, labels = self._get_mapping_labels(self._ptr)
 446         utils._handle_func_status(status, "cannot get label for enumeration field")
 447
 448         assert labels is not None
 449         return labels
 450
 451
 452 class _EnumerationField(_EnumerationFieldConst, _IntegerField):
 453     pass
 454
 455
 456 class _UnsignedEnumerationFieldConst(
 457     _EnumerationFieldConst, _UnsignedIntegerFieldConst
 458 ):
 459     _NAME = 'Const unsigned Enumeration'
 460     _get_mapping_labels = staticmethod(
 461         native_bt.field_enumeration_unsigned_get_mapping_labels
 462     )
 463
 464
 465 class _UnsignedEnumerationField(
 466     _UnsignedEnumerationFieldConst, _EnumerationField, _UnsignedIntegerField
 467 ):
 468     _NAME = 'Unsigned enumeration'
 469
 470
 471 class _SignedEnumerationFieldConst(_EnumerationFieldConst, _SignedIntegerFieldConst):
 472     _NAME = 'Const signed Enumeration'
 473     _get_mapping_labels = staticmethod(
 474         native_bt.field_enumeration_signed_get_mapping_labels
 475     )
 476
 477
 478 class _SignedEnumerationField(
 479     _SignedEnumerationFieldConst, _EnumerationField, _SignedIntegerField
 480 ):
 481     _NAME = 'Signed enumeration'
 482
 483
 484 @functools.total_ordering
 485 class _StringFieldConst(_FieldConst):
 486     _NAME = 'Const string'
 487
 488     @classmethod
 489     def _value_to_str(cls, value):
 490         if isinstance(value, _StringFieldConst):
 491             value = value._value
 492
 493         if not isinstance(value, str):
 494             raise TypeError("expecting a 'str' object")
 495
 496         return value
 497
 498     @property
 499     def _value(self):
 500         return native_bt.field_string_get_value(self._ptr)
 501
 502     def _spec_eq(self, other):
 503         try:
 504             return self._value == self._value_to_str(other)
 505         except Exception:
 506             return False
 507
 508     def __lt__(self, other):
 509         return self._value < self._value_to_str(other)
 510
 511     def __bool__(self):
 512         return bool(self._value)
 513
 514     def __hash__(self):
 515         return hash(self._value)
 516
 517     def _repr(self):
 518         return repr(self._value)
 519
 520     def __str__(self):
 521         return str(self._value)
 522
 523     def __getitem__(self, index):
 524         return self._value[index]
 525
 526     def __len__(self):
 527         return native_bt.field_string_get_length(self._ptr)
 528
 529
 530 class _StringField(_StringFieldConst, _Field):
 531     _NAME = 'String'
 532
 533     def _set_value(self, value):
 534         value = self._value_to_str(value)
 535         native_bt.field_string_set_value(self._ptr, value)
 536
 537     value = property(fset=_set_value)
 538
 539     def __iadd__(self, value):
 540         value = self._value_to_str(value)
 541         status = native_bt.field_string_append(self._ptr, value)
 542         utils._handle_func_status(
 543             status, "cannot append to string field object's value"
 544         )
 545         return self
 546
 547     def __hash__(self):
 548         # Non const field are not hashable as their value may be modified
 549         # without changing the underlying Python object.
 550         raise TypeError('unhashable type: \'{}\''.format(self._NAME))
 551
 552
 553 class _ContainerFieldConst(_FieldConst):
 554     def __bool__(self):
 555         return len(self) != 0
 556
 557     def _count(self):
 558         return len(self.cls)
 559
 560     def __len__(self):
 561         count = self._count()
 562         assert count >= 0
 563         return count
 564
 565     def __delitem__(self, index):
 566         raise NotImplementedError
 567
 568     def __setitem__(self, index, value):
 569         raise TypeError(
 570             '\'{}\' object does not support item assignment'.format(self.__class__)
 571         )
 572
 573
 574 class _ContainerField(_ContainerFieldConst, _Field):
 575     pass
 576
 577
 578 class _StructureFieldConst(_ContainerFieldConst, collections.abc.Mapping):
 579     _NAME = 'Const structure'
 580     _borrow_member_field_ptr_by_index = staticmethod(
 581         native_bt.field_structure_borrow_member_field_by_index_const
 582     )
 583     _borrow_member_field_ptr_by_name = staticmethod(
 584         native_bt.field_structure_borrow_member_field_by_name_const
 585     )
 586
 587     def _count(self):
 588         return len(self.cls)
 589
 590     def __iter__(self):
 591         # same name iterator
 592         return iter(self.cls)
 593
 594     def _spec_eq(self, other):
 595         if not isinstance(other, collections.abc.Mapping):
 596             return False
 597
 598         if len(self) != len(other):
 599             # early mismatch
 600             return False
 601
 602         for self_key in self:
 603             if self_key not in other:
 604                 return False
 605
 606             if self[self_key] != other[self_key]:
 607                 return False
 608
 609         return True
 610
 611     def _repr(self):
 612         items = ['{}: {}'.format(repr(k), repr(v)) for k, v in self.items()]
 613         return '{{{}}}'.format(', '.join(items))
 614
 615     def __getitem__(self, key):
 616         utils._check_str(key)
 617         field_ptr = self._borrow_member_field_ptr_by_name(self._ptr, key)
 618
 619         if field_ptr is None:
 620             raise KeyError(key)
 621
 622         return self._create_field_from_ptr(
 623             field_ptr, self._owner_ptr, self._owner_get_ref, self._owner_put_ref
 624         )
 625
 626     def member_at_index(self, index):
 627         utils._check_uint64(index)
 628
 629         if index >= len(self):
 630             raise IndexError
 631         field_ptr = self._borrow_member_field_ptr_by_index(self._ptr, index)
 632         assert field_ptr is not None
 633         return self._create_field_from_ptr(
 634             field_ptr, self._owner_ptr, self._owner_get_ref, self._owner_put_ref
 635         )
 636
 637
 638 class _StructureField(
 639     _StructureFieldConst, _ContainerField, collections.abc.MutableMapping
 640 ):
 641     _NAME = 'Structure'
 642     _borrow_member_field_ptr_by_index = staticmethod(
 643         native_bt.field_structure_borrow_member_field_by_index
 644     )
 645     _borrow_member_field_ptr_by_name = staticmethod(
 646         native_bt.field_structure_borrow_member_field_by_name
 647     )
 648
 649     def __setitem__(self, key, value):
 650         # raises if key is somehow invalid
 651         field = self[key]
 652
 653         # the field's property does the appropriate conversion or raises
 654         # the appropriate exception
 655         field.value = value
 656
 657     def _set_value(self, values):
 658         try:
 659             for key, value in values.items():
 660                 self[key].value = value
 661         except Exception:
 662             raise
 663
 664     value = property(fset=_set_value)
 665
 666
 667 class _OptionFieldConst(_FieldConst):
 668     _NAME = 'Const option'
 669     _borrow_field_ptr = staticmethod(native_bt.field_option_borrow_field_const)
 670
 671     @property
 672     def field(self):
 673         field_ptr = self._borrow_field_ptr(self._ptr)
 674
 675         if field_ptr is None:
 676             return
 677
 678         return self._create_field_from_ptr(
 679             field_ptr, self._owner_ptr, self._owner_get_ref, self._owner_put_ref
 680         )
 681
 682     @property
 683     def has_field(self):
 684         return self.field is not None
 685
 686     def _spec_eq(self, other):
 687         return _get_leaf_field(self) == other
 688
 689     def __bool__(self):
 690         return self.has_field
 691
 692     def __str__(self):
 693         return str(self.field)
 694
 695     def _repr(self):
 696         return repr(self.field)
 697
 698
 699 class _OptionField(_OptionFieldConst, _Field):
 700     _NAME = 'Option'
 701     _borrow_field_ptr = staticmethod(native_bt.field_option_borrow_field)
 702
 703     def _has_field(self, value):
 704         utils._check_bool(value)
 705         native_bt.field_option_set_has_field(self._ptr, value)
 706
 707     has_field = property(fget=_OptionFieldConst.has_field.fget, fset=_has_field)
 708
 709     def _set_value(self, value):
 710         self.has_field = True
 711         field = self.field
 712         assert field is not None
 713         field.value = value
 714
 715     value = property(fset=_set_value)
 716
 717
 718 class _VariantFieldConst(_ContainerFieldConst, _FieldConst):
 719     _NAME = 'Const variant'
 720     _borrow_selected_option_field_ptr = staticmethod(
 721         native_bt.field_variant_borrow_selected_option_field_const
 722     )
 723
 724     def _count(self):
 725         return len(self.cls)
 726
 727     @property
 728     def selected_option_index(self):
 729         return native_bt.field_variant_get_selected_option_field_index(self._ptr)
 730
 731     @property
 732     def selected_option(self):
 733         # TODO: Is there a way to check if the variant field has a selected_option,
 734         # so we can raise an exception instead of hitting a pre-condition check?
 735         # If there is something, that check should be added to selected_option_index too.
 736         field_ptr = self._borrow_selected_option_field_ptr(self._ptr)
 737
 738         return self._create_field_from_ptr(
 739             field_ptr, self._owner_ptr, self._owner_get_ref, self._owner_put_ref
 740         )
 741
 742     def _spec_eq(self, other):
 743         return _get_leaf_field(self) == other
 744
 745     def __bool__(self):
 746         raise NotImplementedError
 747
 748     def __str__(self):
 749         return str(self.selected_option)
 750
 751     def _repr(self):
 752         return repr(self.selected_option)
 753
 754
 755 class _VariantField(_VariantFieldConst, _ContainerField, _Field):
 756     _NAME = 'Variant'
 757     _borrow_selected_option_field_ptr = staticmethod(
 758         native_bt.field_variant_borrow_selected_option_field
 759     )
 760
 761     def _selected_option_index(self, index):
 762         if index < 0 or index >= len(self):
 763             raise IndexError('{} field object index is out of range'.format(self._NAME))
 764
 765         native_bt.field_variant_select_option_field_by_index(self._ptr, index)
 766
 767     selected_option_index = property(
 768         fget=_VariantFieldConst.selected_option_index.fget, fset=_selected_option_index
 769     )
 770
 771     def _set_value(self, value):
 772         self.selected_option.value = value
 773
 774     value = property(fset=_set_value)
 775
 776
 777 class _ArrayFieldConst(_ContainerFieldConst, _FieldConst, collections.abc.Sequence):
 778     _borrow_element_field_ptr_by_index = staticmethod(
 779         native_bt.field_array_borrow_element_field_by_index_const
 780     )
 781
 782     def _get_length(self):
 783         return native_bt.field_array_get_length(self._ptr)
 784
 785     length = property(fget=_get_length)
 786
 787     def __getitem__(self, index):
 788         if not isinstance(index, numbers.Integral):
 789             raise TypeError(
 790                 "'{}' is not an integral number object: invalid index".format(
 791                     index.__class__.__name__
 792                 )
 793             )
 794
 795         index = int(index)
 796
 797         if index < 0 or index >= len(self):
 798             raise IndexError('{} field object index is out of range'.format(self._NAME))
 799
 800         field_ptr = self._borrow_element_field_ptr_by_index(self._ptr, index)
 801         assert field_ptr
 802         return self._create_field_from_ptr(
 803             field_ptr, self._owner_ptr, self._owner_get_ref, self._owner_put_ref
 804         )
 805
 806     def insert(self, index, value):
 807         raise NotImplementedError
 808
 809     def _spec_eq(self, other):
 810         if not isinstance(other, collections.abc.Sequence):
 811             return False
 812
 813         if len(self) != len(other):
 814             # early mismatch
 815             return False
 816
 817         for self_elem, other_elem in zip(self, other):
 818             if self_elem != other_elem:
 819                 return False
 820
 821         return True
 822
 823     def _repr(self):
 824         return '[{}]'.format(', '.join([repr(v) for v in self]))
 825
 826
 827 class _ArrayField(
 828     _ArrayFieldConst, _ContainerField, _Field, collections.abc.MutableSequence
 829 ):
 830     _borrow_element_field_ptr_by_index = staticmethod(
 831         native_bt.field_array_borrow_element_field_by_index
 832     )
 833
 834     def __setitem__(self, index, value):
 835         # raises if index is somehow invalid
 836         field = self[index]
 837
 838         if not isinstance(field, (_NumericField, _StringField)):
 839             raise TypeError('can only set the value of a number or string field')
 840
 841         # the field's property does the appropriate conversion or raises
 842         # the appropriate exception
 843         field.value = value
 844
 845
 846 class _StaticArrayFieldConst(_ArrayFieldConst, _FieldConst):
 847     _NAME = 'Const static array'
 848
 849     def _count(self):
 850         return native_bt.field_array_get_length(self._ptr)
 851
 852
 853 class _StaticArrayField(_StaticArrayFieldConst, _ArrayField, _Field):
 854     _NAME = 'Static array'
 855
 856     def _set_value(self, values):
 857         if len(self) != len(values):
 858             raise ValueError('expected length of value and array field to match')
 859
 860         for index, value in enumerate(values):
 861             if value is not None:
 862                 self[index].value = value
 863
 864     value = property(fset=_set_value)
 865
 866
 867 class _DynamicArrayFieldConst(_ArrayFieldConst, _FieldConst):
 868     _NAME = 'Const dynamic array'
 869
 870     def _count(self):
 871         return self.length
 872
 873
 874 class _DynamicArrayField(_DynamicArrayFieldConst, _ArrayField, _Field):
 875     _NAME = 'Dynamic array'
 876
 877     def _set_length(self, length):
 878         utils._check_uint64(length)
 879         status = native_bt.field_array_dynamic_set_length(self._ptr, length)
 880         utils._handle_func_status(status, "cannot set dynamic array length")
 881
 882     length = property(fget=_ArrayField._get_length, fset=_set_length)
 883
 884     def _set_value(self, values):
 885         if len(values) != self.length:
 886             self.length = len(values)
 887
 888         for index, value in enumerate(values):
 889             if value is not None:
 890                 self[index].value = value
 891
 892     value = property(fset=_set_value)
 893
 894
 895 _TYPE_ID_TO_CONST_OBJ = {
 896     native_bt.FIELD_CLASS_TYPE_BOOL: _BoolFieldConst,
 897     native_bt.FIELD_CLASS_TYPE_BIT_ARRAY: _BitArrayFieldConst,
 898     native_bt.FIELD_CLASS_TYPE_UNSIGNED_INTEGER: _UnsignedIntegerFieldConst,
 899     native_bt.FIELD_CLASS_TYPE_SIGNED_INTEGER: _SignedIntegerFieldConst,
 900     native_bt.FIELD_CLASS_TYPE_REAL: _RealFieldConst,
 901     native_bt.FIELD_CLASS_TYPE_UNSIGNED_ENUMERATION: _UnsignedEnumerationFieldConst,
 902     native_bt.FIELD_CLASS_TYPE_SIGNED_ENUMERATION: _SignedEnumerationFieldConst,
 903     native_bt.FIELD_CLASS_TYPE_STRING: _StringFieldConst,
 904     native_bt.FIELD_CLASS_TYPE_STRUCTURE: _StructureFieldConst,
 905     native_bt.FIELD_CLASS_TYPE_STATIC_ARRAY: _StaticArrayFieldConst,
 906     native_bt.FIELD_CLASS_TYPE_DYNAMIC_ARRAY: _DynamicArrayFieldConst,
 907     native_bt.FIELD_CLASS_TYPE_OPTION: _OptionFieldConst,
 908     native_bt.FIELD_CLASS_TYPE_VARIANT_WITHOUT_SELECTOR: _VariantFieldConst,
 909     native_bt.FIELD_CLASS_TYPE_VARIANT_WITH_UNSIGNED_SELECTOR: _VariantFieldConst,
 910     native_bt.FIELD_CLASS_TYPE_VARIANT_WITH_SIGNED_SELECTOR: _VariantFieldConst,
 911 }
 912
 913 _TYPE_ID_TO_OBJ = {
 914     native_bt.FIELD_CLASS_TYPE_BOOL: _BoolField,
 915     native_bt.FIELD_CLASS_TYPE_BIT_ARRAY: _BitArrayField,
 916     native_bt.FIELD_CLASS_TYPE_UNSIGNED_INTEGER: _UnsignedIntegerField,
 917     native_bt.FIELD_CLASS_TYPE_SIGNED_INTEGER: _SignedIntegerField,
 918     native_bt.FIELD_CLASS_TYPE_REAL: _RealField,
 919     native_bt.FIELD_CLASS_TYPE_UNSIGNED_ENUMERATION: _UnsignedEnumerationField,
 920     native_bt.FIELD_CLASS_TYPE_SIGNED_ENUMERATION: _SignedEnumerationField,
 921     native_bt.FIELD_CLASS_TYPE_STRING: _StringField,
 922     native_bt.FIELD_CLASS_TYPE_STRUCTURE: _StructureField,
 923     native_bt.FIELD_CLASS_TYPE_STATIC_ARRAY: _StaticArrayField,
 924     native_bt.FIELD_CLASS_TYPE_DYNAMIC_ARRAY: _DynamicArrayField,
 925     native_bt.FIELD_CLASS_TYPE_OPTION: _OptionField,
 926     native_bt.FIELD_CLASS_TYPE_VARIANT_WITHOUT_SELECTOR: _VariantField,
 927     native_bt.FIELD_CLASS_TYPE_VARIANT_WITH_UNSIGNED_SELECTOR: _VariantField,
 928     native_bt.FIELD_CLASS_TYPE_VARIANT_WITH_SIGNED_SELECTOR: _VariantField,
 929 }