/usr/share/pyshared/sqlalchemy/orm/collections.py is in python-sqlalchemy 0.7.4-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 | # orm/collections.py
# Copyright (C) 2005-2011 the SQLAlchemy authors and contributors <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""Support for collections of mapped entities.
The collections package supplies the machinery used to inform the ORM of
collection membership changes. An instrumentation via decoration approach is
used, allowing arbitrary types (including built-ins) to be used as entity
collections without requiring inheritance from a base class.
Instrumentation decoration relays membership change events to the
``InstrumentedCollectionAttribute`` that is currently managing the collection.
The decorators observe function call arguments and return values, tracking
entities entering or leaving the collection. Two decorator approaches are
provided. One is a bundle of generic decorators that map function arguments
and return values to events::
from sqlalchemy.orm.collections import collection
class MyClass(object):
# ...
@collection.adds(1)
def store(self, item):
self.data.append(item)
@collection.removes_return()
def pop(self):
return self.data.pop()
The second approach is a bundle of targeted decorators that wrap appropriate
append and remove notifiers around the mutation methods present in the
standard Python ``list``, ``set`` and ``dict`` interfaces. These could be
specified in terms of generic decorator recipes, but are instead hand-tooled
for increased efficiency. The targeted decorators occasionally implement
adapter-like behavior, such as mapping bulk-set methods (``extend``,
``update``, ``__setslice__``, etc.) into the series of atomic mutation events
that the ORM requires.
The targeted decorators are used internally for automatic instrumentation of
entity collection classes. Every collection class goes through a
transformation process roughly like so:
1. If the class is a built-in, substitute a trivial sub-class
2. Is this class already instrumented?
3. Add in generic decorators
4. Sniff out the collection interface through duck-typing
5. Add targeted decoration to any undecorated interface method
This process modifies the class at runtime, decorating methods and adding some
bookkeeping properties. This isn't possible (or desirable) for built-in
classes like ``list``, so trivial sub-classes are substituted to hold
decoration::
class InstrumentedList(list):
pass
Collection classes can be specified in ``relationship(collection_class=)`` as
types or a function that returns an instance. Collection classes are
inspected and instrumented during the mapper compilation phase. The
collection_class callable will be executed once to produce a specimen
instance, and the type of that specimen will be instrumented. Functions that
return built-in types like ``lists`` will be adapted to produce instrumented
instances.
When extending a known type like ``list``, additional decorations are not
generally not needed. Odds are, the extension method will delegate to a
method that's already instrumented. For example::
class QueueIsh(list):
def push(self, item):
self.append(item)
def shift(self):
return self.pop(0)
There's no need to decorate these methods. ``append`` and ``pop`` are already
instrumented as part of the ``list`` interface. Decorating them would fire
duplicate events, which should be avoided.
The targeted decoration tries not to rely on other methods in the underlying
collection class, but some are unavoidable. Many depend on 'read' methods
being present to properly instrument a 'write', for example, ``__setitem__``
needs ``__getitem__``. "Bulk" methods like ``update`` and ``extend`` may also
reimplemented in terms of atomic appends and removes, so the ``extend``
decoration will actually perform many ``append`` operations and not call the
underlying method at all.
Tight control over bulk operation and the firing of events is also possible by
implementing the instrumentation internally in your methods. The basic
instrumentation package works under the general assumption that collection
mutation will not raise unusual exceptions. If you want to closely
orchestrate append and remove events with exception management, internal
instrumentation may be the answer. Within your method,
``collection_adapter(self)`` will retrieve an object that you can use for
explicit control over triggering append and remove events.
The owning object and InstrumentedCollectionAttribute are also reachable
through the adapter, allowing for some very sophisticated behavior.
"""
import copy
import inspect
import operator
import sys
import weakref
from sqlalchemy.sql import expression
from sqlalchemy import schema, util, exc as sa_exc
__all__ = ['collection', 'collection_adapter',
'mapped_collection', 'column_mapped_collection',
'attribute_mapped_collection']
__instrumentation_mutex = util.threading.Lock()
def column_mapped_collection(mapping_spec):
"""A dictionary-based collection type with column-based keying.
Returns a :class:`.MappedCollection` factory with a keying function generated
from mapping_spec, which may be a Column or a sequence of Columns.
The key value must be immutable for the lifetime of the object. You
can not, for example, map on foreign key values if those key values will
change during the session, i.e. from None to a database-assigned integer
after a session flush.
"""
from sqlalchemy.orm.util import _state_mapper
from sqlalchemy.orm.attributes import instance_state
cols = [expression._only_column_elements(q, "mapping_spec")
for q in util.to_list(mapping_spec)]
if len(cols) == 1:
def keyfunc(value):
state = instance_state(value)
m = _state_mapper(state)
return m._get_state_attr_by_column(state, state.dict, cols[0])
else:
mapping_spec = tuple(cols)
def keyfunc(value):
state = instance_state(value)
m = _state_mapper(state)
return tuple(m._get_state_attr_by_column(state, state.dict, c)
for c in mapping_spec)
return lambda: MappedCollection(keyfunc)
def attribute_mapped_collection(attr_name):
"""A dictionary-based collection type with attribute-based keying.
Returns a :class:`.MappedCollection` factory with a keying based on the
'attr_name' attribute of entities in the collection, where ``attr_name``
is the string name of the attribute.
The key value must be immutable for the lifetime of the object. You
can not, for example, map on foreign key values if those key values will
change during the session, i.e. from None to a database-assigned integer
after a session flush.
"""
return lambda: MappedCollection(operator.attrgetter(attr_name))
def mapped_collection(keyfunc):
"""A dictionary-based collection type with arbitrary keying.
Returns a :class:`.MappedCollection` factory with a keying function generated
from keyfunc, a callable that takes an entity and returns a key value.
The key value must be immutable for the lifetime of the object. You
can not, for example, map on foreign key values if those key values will
change during the session, i.e. from None to a database-assigned integer
after a session flush.
"""
return lambda: MappedCollection(keyfunc)
class collection(object):
"""Decorators for entity collection classes.
The decorators fall into two groups: annotations and interception recipes.
The annotating decorators (appender, remover, iterator,
internally_instrumented, link) indicate the method's purpose and take no
arguments. They are not written with parens::
@collection.appender
def append(self, append): ...
The recipe decorators all require parens, even those that take no
arguments::
@collection.adds('entity')
def insert(self, position, entity): ...
@collection.removes_return()
def popitem(self): ...
"""
# Bundled as a class solely for ease of use: packaging, doc strings,
# importability.
@staticmethod
def appender(fn):
"""Tag the method as the collection appender.
The appender method is called with one positional argument: the value
to append. The method will be automatically decorated with 'adds(1)'
if not already decorated::
@collection.appender
def add(self, append): ...
# or, equivalently
@collection.appender
@collection.adds(1)
def add(self, append): ...
# for mapping type, an 'append' may kick out a previous value
# that occupies that slot. consider d['a'] = 'foo'- any previous
# value in d['a'] is discarded.
@collection.appender
@collection.replaces(1)
def add(self, entity):
key = some_key_func(entity)
previous = None
if key in self:
previous = self[key]
self[key] = entity
return previous
If the value to append is not allowed in the collection, you may
raise an exception. Something to remember is that the appender
will be called for each object mapped by a database query. If the
database contains rows that violate your collection semantics, you
will need to get creative to fix the problem, as access via the
collection will not work.
If the appender method is internally instrumented, you must also
receive the keyword argument '_sa_initiator' and ensure its
promulgation to collection events.
"""
setattr(fn, '_sa_instrument_role', 'appender')
return fn
@staticmethod
def remover(fn):
"""Tag the method as the collection remover.
The remover method is called with one positional argument: the value
to remove. The method will be automatically decorated with
:meth:`removes_return` if not already decorated::
@collection.remover
def zap(self, entity): ...
# or, equivalently
@collection.remover
@collection.removes_return()
def zap(self, ): ...
If the value to remove is not present in the collection, you may
raise an exception or return None to ignore the error.
If the remove method is internally instrumented, you must also
receive the keyword argument '_sa_initiator' and ensure its
promulgation to collection events.
"""
setattr(fn, '_sa_instrument_role', 'remover')
return fn
@staticmethod
def iterator(fn):
"""Tag the method as the collection remover.
The iterator method is called with no arguments. It is expected to
return an iterator over all collection members::
@collection.iterator
def __iter__(self): ...
"""
setattr(fn, '_sa_instrument_role', 'iterator')
return fn
@staticmethod
def internally_instrumented(fn):
"""Tag the method as instrumented.
This tag will prevent any decoration from being applied to the method.
Use this if you are orchestrating your own calls to :func:`.collection_adapter`
in one of the basic SQLAlchemy interface methods, or to prevent
an automatic ABC method decoration from wrapping your implementation::
# normally an 'extend' method on a list-like class would be
# automatically intercepted and re-implemented in terms of
# SQLAlchemy events and append(). your implementation will
# never be called, unless:
@collection.internally_instrumented
def extend(self, items): ...
"""
setattr(fn, '_sa_instrumented', True)
return fn
@staticmethod
def link(fn):
"""Tag the method as a the "linked to attribute" event handler.
This optional event handler will be called when the collection class
is linked to or unlinked from the InstrumentedAttribute. It is
invoked immediately after the '_sa_adapter' property is set on
the instance. A single argument is passed: the collection adapter
that has been linked, or None if unlinking.
"""
setattr(fn, '_sa_instrument_role', 'link')
return fn
@staticmethod
def converter(fn):
"""Tag the method as the collection converter.
This optional method will be called when a collection is being
replaced entirely, as in::
myobj.acollection = [newvalue1, newvalue2]
The converter method will receive the object being assigned and should
return an iterable of values suitable for use by the ``appender``
method. A converter must not assign values or mutate the collection,
it's sole job is to adapt the value the user provides into an iterable
of values for the ORM's use.
The default converter implementation will use duck-typing to do the
conversion. A dict-like collection will be convert into an iterable
of dictionary values, and other types will simply be iterated::
@collection.converter
def convert(self, other): ...
If the duck-typing of the object does not match the type of this
collection, a TypeError is raised.
Supply an implementation of this method if you want to expand the
range of possible types that can be assigned in bulk or perform
validation on the values about to be assigned.
"""
setattr(fn, '_sa_instrument_role', 'converter')
return fn
@staticmethod
def adds(arg):
"""Mark the method as adding an entity to the collection.
Adds "add to collection" handling to the method. The decorator
argument indicates which method argument holds the SQLAlchemy-relevant
value. Arguments can be specified positionally (i.e. integer) or by
name::
@collection.adds(1)
def push(self, item): ...
@collection.adds('entity')
def do_stuff(self, thing, entity=None): ...
"""
def decorator(fn):
setattr(fn, '_sa_instrument_before', ('fire_append_event', arg))
return fn
return decorator
@staticmethod
def replaces(arg):
"""Mark the method as replacing an entity in the collection.
Adds "add to collection" and "remove from collection" handling to
the method. The decorator argument indicates which method argument
holds the SQLAlchemy-relevant value to be added, and return value, if
any will be considered the value to remove.
Arguments can be specified positionally (i.e. integer) or by name::
@collection.replaces(2)
def __setitem__(self, index, item): ...
"""
def decorator(fn):
setattr(fn, '_sa_instrument_before', ('fire_append_event', arg))
setattr(fn, '_sa_instrument_after', 'fire_remove_event')
return fn
return decorator
@staticmethod
def removes(arg):
"""Mark the method as removing an entity in the collection.
Adds "remove from collection" handling to the method. The decorator
argument indicates which method argument holds the SQLAlchemy-relevant
value to be removed. Arguments can be specified positionally (i.e.
integer) or by name::
@collection.removes(1)
def zap(self, item): ...
For methods where the value to remove is not known at call-time, use
collection.removes_return.
"""
def decorator(fn):
setattr(fn, '_sa_instrument_before', ('fire_remove_event', arg))
return fn
return decorator
@staticmethod
def removes_return():
"""Mark the method as removing an entity in the collection.
Adds "remove from collection" handling to the method. The return value
of the method, if any, is considered the value to remove. The method
arguments are not inspected::
@collection.removes_return()
def pop(self): ...
For methods where the value to remove is known at call-time, use
collection.remove.
"""
def decorator(fn):
setattr(fn, '_sa_instrument_after', 'fire_remove_event')
return fn
return decorator
# public instrumentation interface for 'internally instrumented'
# implementations
def collection_adapter(collection):
"""Fetch the :class:`.CollectionAdapter` for a collection."""
return getattr(collection, '_sa_adapter', None)
def collection_iter(collection):
"""Iterate over an object supporting the @iterator or __iter__ protocols.
If the collection is an ORM collection, it need not be attached to an
object to be iterable.
"""
try:
return getattr(collection, '_sa_iterator',
getattr(collection, '__iter__'))()
except AttributeError:
raise TypeError("'%s' object is not iterable" %
type(collection).__name__)
class CollectionAdapter(object):
"""Bridges between the ORM and arbitrary Python collections.
Proxies base-level collection operations (append, remove, iterate)
to the underlying Python collection, and emits add/remove events for
entities entering or leaving the collection.
The ORM uses :class:`.CollectionAdapter` exclusively for interaction with
entity collections.
The usage of getattr()/setattr() is currently to allow injection
of custom methods, such as to unwrap Zope security proxies.
"""
def __init__(self, attr, owner_state, data):
self._key = attr.key
self._data = weakref.ref(data)
self.owner_state = owner_state
self.link_to_self(data)
@property
def data(self):
"The entity collection being adapted."
return self._data()
@util.memoized_property
def attr(self):
return self.owner_state.manager[self._key].impl
def link_to_self(self, data):
"""Link a collection to this adapter, and fire a link event."""
setattr(data, '_sa_adapter', self)
if hasattr(data, '_sa_on_link'):
getattr(data, '_sa_on_link')(self)
def unlink(self, data):
"""Unlink a collection from any adapter, and fire a link event."""
setattr(data, '_sa_adapter', None)
if hasattr(data, '_sa_on_link'):
getattr(data, '_sa_on_link')(None)
def adapt_like_to_iterable(self, obj):
"""Converts collection-compatible objects to an iterable of values.
Can be passed any type of object, and if the underlying collection
determines that it can be adapted into a stream of values it can
use, returns an iterable of values suitable for append()ing.
This method may raise TypeError or any other suitable exception
if adaptation fails.
If a converter implementation is not supplied on the collection,
a default duck-typing-based implementation is used.
"""
converter = getattr(self._data(), '_sa_converter', None)
if converter is not None:
return converter(obj)
setting_type = util.duck_type_collection(obj)
receiving_type = util.duck_type_collection(self._data())
if obj is None or setting_type != receiving_type:
given = obj is None and 'None' or obj.__class__.__name__
if receiving_type is None:
wanted = self._data().__class__.__name__
else:
wanted = receiving_type.__name__
raise TypeError(
"Incompatible collection type: %s is not %s-like" % (
given, wanted))
# If the object is an adapted collection, return the (iterable)
# adapter.
if getattr(obj, '_sa_adapter', None) is not None:
return getattr(obj, '_sa_adapter')
elif setting_type == dict:
# Py3K
#return obj.values()
# Py2K
return getattr(obj, 'itervalues', getattr(obj, 'values'))()
# end Py2K
else:
return iter(obj)
def append_with_event(self, item, initiator=None):
"""Add an entity to the collection, firing mutation events."""
getattr(self._data(), '_sa_appender')(item, _sa_initiator=initiator)
def append_without_event(self, item):
"""Add or restore an entity to the collection, firing no events."""
getattr(self._data(), '_sa_appender')(item, _sa_initiator=False)
def append_multiple_without_event(self, items):
"""Add or restore an entity to the collection, firing no events."""
appender = getattr(self._data(), '_sa_appender')
for item in items:
appender(item, _sa_initiator=False)
def remove_with_event(self, item, initiator=None):
"""Remove an entity from the collection, firing mutation events."""
getattr(self._data(), '_sa_remover')(item, _sa_initiator=initiator)
def remove_without_event(self, item):
"""Remove an entity from the collection, firing no events."""
getattr(self._data(), '_sa_remover')(item, _sa_initiator=False)
def clear_with_event(self, initiator=None):
"""Empty the collection, firing a mutation event for each entity."""
remover = getattr(self._data(), '_sa_remover')
for item in list(self):
remover(item, _sa_initiator=initiator)
def clear_without_event(self):
"""Empty the collection, firing no events."""
remover = getattr(self._data(), '_sa_remover')
for item in list(self):
remover(item, _sa_initiator=False)
def __iter__(self):
"""Iterate over entities in the collection."""
# Py3K requires iter() here
return iter(getattr(self._data(), '_sa_iterator')())
def __len__(self):
"""Count entities in the collection."""
return len(list(getattr(self._data(), '_sa_iterator')()))
def __nonzero__(self):
return True
def fire_append_event(self, item, initiator=None):
"""Notify that a entity has entered the collection.
Initiator is a token owned by the InstrumentedAttribute that initiated the membership
mutation, and should be left as None unless you are passing along
an initiator value from a chained operation.
"""
if initiator is not False and item is not None:
return self.attr.fire_append_event(
self.owner_state,
self.owner_state.dict,
item, initiator)
else:
return item
def fire_remove_event(self, item, initiator=None):
"""Notify that a entity has been removed from the collection.
Initiator is the InstrumentedAttribute that initiated the membership
mutation, and should be left as None unless you are passing along
an initiator value from a chained operation.
"""
if initiator is not False and item is not None:
self.attr.fire_remove_event(
self.owner_state,
self.owner_state.dict,
item, initiator)
def fire_pre_remove_event(self, initiator=None):
"""Notify that an entity is about to be removed from the collection.
Only called if the entity cannot be removed after calling
fire_remove_event().
"""
self.attr.fire_pre_remove_event(
self.owner_state,
self.owner_state.dict,
initiator=initiator)
def __getstate__(self):
return {'key': self._key,
'owner_state': self.owner_state,
'data': self.data}
def __setstate__(self, d):
self._key = d['key']
self.owner_state = d['owner_state']
self._data = weakref.ref(d['data'])
def bulk_replace(values, existing_adapter, new_adapter):
"""Load a new collection, firing events based on prior like membership.
Appends instances in ``values`` onto the ``new_adapter``. Events will be
fired for any instance not present in the ``existing_adapter``. Any
instances in ``existing_adapter`` not present in ``values`` will have
remove events fired upon them.
:param values: An iterable of collection member instances
:param existing_adapter: A :class:`.CollectionAdapter` of instances to be replaced
:param new_adapter: An empty :class:`.CollectionAdapter` to load with ``values``
"""
if not isinstance(values, list):
values = list(values)
idset = util.IdentitySet
constants = idset(existing_adapter or ()).intersection(values or ())
additions = idset(values or ()).difference(constants)
removals = idset(existing_adapter or ()).difference(constants)
for member in values or ():
if member in additions:
new_adapter.append_with_event(member)
elif member in constants:
new_adapter.append_without_event(member)
if existing_adapter:
for member in removals:
existing_adapter.remove_with_event(member)
def prepare_instrumentation(factory):
"""Prepare a callable for future use as a collection class factory.
Given a collection class factory (either a type or no-arg callable),
return another factory that will produce compatible instances when
called.
This function is responsible for converting collection_class=list
into the run-time behavior of collection_class=InstrumentedList.
"""
# Convert a builtin to 'Instrumented*'
if factory in __canned_instrumentation:
factory = __canned_instrumentation[factory]
# Create a specimen
cls = type(factory())
# Did factory callable return a builtin?
if cls in __canned_instrumentation:
# Wrap it so that it returns our 'Instrumented*'
factory = __converting_factory(factory)
cls = factory()
# Instrument the class if needed.
if __instrumentation_mutex.acquire():
try:
if getattr(cls, '_sa_instrumented', None) != id(cls):
_instrument_class(cls)
finally:
__instrumentation_mutex.release()
return factory
def __converting_factory(original_factory):
"""Convert the type returned by collection factories on the fly.
Given a collection factory that returns a builtin type (e.g. a list),
return a wrapped function that converts that type to one of our
instrumented types.
"""
def wrapper():
collection = original_factory()
type_ = type(collection)
if type_ in __canned_instrumentation:
# return an instrumented type initialized from the factory's
# collection
return __canned_instrumentation[type_](collection)
else:
raise sa_exc.InvalidRequestError(
"Collection class factories must produce instances of a "
"single class.")
try:
# often flawed but better than nothing
wrapper.__name__ = "%sWrapper" % original_factory.__name__
wrapper.__doc__ = original_factory.__doc__
except:
pass
return wrapper
def _instrument_class(cls):
"""Modify methods in a class and install instrumentation."""
# TODO: more formally document this as a decoratorless/Python 2.3
# option for specifying instrumentation. (likely doc'd here in code only,
# not in online docs.) Useful for C types too.
#
# __instrumentation__ = {
# 'rolename': 'methodname', # ...
# 'methods': {
# 'methodname': ('fire_{append,remove}_event', argspec,
# 'fire_{append,remove}_event'),
# 'append': ('fire_append_event', 1, None),
# '__setitem__': ('fire_append_event', 1, 'fire_remove_event'),
# 'pop': (None, None, 'fire_remove_event'),
# }
# }
# In the normal call flow, a request for any of the 3 basic collection
# types is transformed into one of our trivial subclasses
# (e.g. InstrumentedList). Catch anything else that sneaks in here...
if cls.__module__ == '__builtin__':
raise sa_exc.ArgumentError(
"Can not instrument a built-in type. Use a "
"subclass, even a trivial one.")
collection_type = util.duck_type_collection(cls)
if collection_type in __interfaces:
roles = __interfaces[collection_type].copy()
decorators = roles.pop('_decorators', {})
else:
roles, decorators = {}, {}
if hasattr(cls, '__instrumentation__'):
roles.update(copy.deepcopy(getattr(cls, '__instrumentation__')))
methods = roles.pop('methods', {})
for name in dir(cls):
method = getattr(cls, name, None)
if not util.callable(method):
continue
# note role declarations
if hasattr(method, '_sa_instrument_role'):
role = method._sa_instrument_role
assert role in ('appender', 'remover', 'iterator',
'link', 'converter')
roles[role] = name
# transfer instrumentation requests from decorated function
# to the combined queue
before, after = None, None
if hasattr(method, '_sa_instrument_before'):
op, argument = method._sa_instrument_before
assert op in ('fire_append_event', 'fire_remove_event')
before = op, argument
if hasattr(method, '_sa_instrument_after'):
op = method._sa_instrument_after
assert op in ('fire_append_event', 'fire_remove_event')
after = op
if before:
methods[name] = before[0], before[1], after
elif after:
methods[name] = None, None, after
# apply ABC auto-decoration to methods that need it
for method, decorator in decorators.items():
fn = getattr(cls, method, None)
if (fn and method not in methods and
not hasattr(fn, '_sa_instrumented')):
setattr(cls, method, decorator(fn))
# ensure all roles are present, and apply implicit instrumentation if
# needed
if 'appender' not in roles or not hasattr(cls, roles['appender']):
raise sa_exc.ArgumentError(
"Type %s must elect an appender method to be "
"a collection class" % cls.__name__)
elif (roles['appender'] not in methods and
not hasattr(getattr(cls, roles['appender']), '_sa_instrumented')):
methods[roles['appender']] = ('fire_append_event', 1, None)
if 'remover' not in roles or not hasattr(cls, roles['remover']):
raise sa_exc.ArgumentError(
"Type %s must elect a remover method to be "
"a collection class" % cls.__name__)
elif (roles['remover'] not in methods and
not hasattr(getattr(cls, roles['remover']), '_sa_instrumented')):
methods[roles['remover']] = ('fire_remove_event', 1, None)
if 'iterator' not in roles or not hasattr(cls, roles['iterator']):
raise sa_exc.ArgumentError(
"Type %s must elect an iterator method to be "
"a collection class" % cls.__name__)
# apply ad-hoc instrumentation from decorators, class-level defaults
# and implicit role declarations
for method, (before, argument, after) in methods.items():
setattr(cls, method,
_instrument_membership_mutator(getattr(cls, method),
before, argument, after))
# intern the role map
for role, method in roles.items():
setattr(cls, '_sa_%s' % role, getattr(cls, method))
setattr(cls, '_sa_instrumented', id(cls))
def _instrument_membership_mutator(method, before, argument, after):
"""Route method args and/or return value through the collection adapter."""
# This isn't smart enough to handle @adds(1) for 'def fn(self, (a, b))'
if before:
fn_args = list(util.flatten_iterator(inspect.getargspec(method)[0]))
if type(argument) is int:
pos_arg = argument
named_arg = len(fn_args) > argument and fn_args[argument] or None
else:
if argument in fn_args:
pos_arg = fn_args.index(argument)
else:
pos_arg = None
named_arg = argument
del fn_args
def wrapper(*args, **kw):
if before:
if pos_arg is None:
if named_arg not in kw:
raise sa_exc.ArgumentError(
"Missing argument %s" % argument)
value = kw[named_arg]
else:
if len(args) > pos_arg:
value = args[pos_arg]
elif named_arg in kw:
value = kw[named_arg]
else:
raise sa_exc.ArgumentError(
"Missing argument %s" % argument)
initiator = kw.pop('_sa_initiator', None)
if initiator is False:
executor = None
else:
executor = getattr(args[0], '_sa_adapter', None)
if before and executor:
getattr(executor, before)(value, initiator)
if not after or not executor:
return method(*args, **kw)
else:
res = method(*args, **kw)
if res is not None:
getattr(executor, after)(res, initiator)
return res
try:
wrapper._sa_instrumented = True
wrapper.__name__ = method.__name__
wrapper.__doc__ = method.__doc__
except:
pass
return wrapper
def __set(collection, item, _sa_initiator=None):
"""Run set events, may eventually be inlined into decorators."""
if _sa_initiator is not False and item is not None:
executor = getattr(collection, '_sa_adapter', None)
if executor:
item = getattr(executor, 'fire_append_event')(item, _sa_initiator)
return item
def __del(collection, item, _sa_initiator=None):
"""Run del events, may eventually be inlined into decorators."""
if _sa_initiator is not False and item is not None:
executor = getattr(collection, '_sa_adapter', None)
if executor:
getattr(executor, 'fire_remove_event')(item, _sa_initiator)
def __before_delete(collection, _sa_initiator=None):
"""Special method to run 'commit existing value' methods"""
executor = getattr(collection, '_sa_adapter', None)
if executor:
getattr(executor, 'fire_pre_remove_event')(_sa_initiator)
def _list_decorators():
"""Tailored instrumentation wrappers for any list-like class."""
def _tidy(fn):
setattr(fn, '_sa_instrumented', True)
fn.__doc__ = getattr(getattr(list, fn.__name__), '__doc__')
def append(fn):
def append(self, item, _sa_initiator=None):
item = __set(self, item, _sa_initiator)
fn(self, item)
_tidy(append)
return append
def remove(fn):
def remove(self, value, _sa_initiator=None):
__before_delete(self, _sa_initiator)
# testlib.pragma exempt:__eq__
fn(self, value)
__del(self, value, _sa_initiator)
_tidy(remove)
return remove
def insert(fn):
def insert(self, index, value):
value = __set(self, value)
fn(self, index, value)
_tidy(insert)
return insert
def __setitem__(fn):
def __setitem__(self, index, value):
if not isinstance(index, slice):
existing = self[index]
if existing is not None:
__del(self, existing)
value = __set(self, value)
fn(self, index, value)
else:
# slice assignment requires __delitem__, insert, __len__
step = index.step or 1
start = index.start or 0
if start < 0:
start += len(self)
stop = index.stop or len(self)
if stop < 0:
stop += len(self)
if step == 1:
for i in xrange(start, stop, step):
if len(self) > start:
del self[start]
for i, item in enumerate(value):
self.insert(i + start, item)
else:
rng = range(start, stop, step)
if len(value) != len(rng):
raise ValueError(
"attempt to assign sequence of size %s to "
"extended slice of size %s" % (len(value),
len(rng)))
for i, item in zip(rng, value):
self.__setitem__(i, item)
_tidy(__setitem__)
return __setitem__
def __delitem__(fn):
def __delitem__(self, index):
if not isinstance(index, slice):
item = self[index]
__del(self, item)
fn(self, index)
else:
# slice deletion requires __getslice__ and a slice-groking
# __getitem__ for stepped deletion
# note: not breaking this into atomic dels
for item in self[index]:
__del(self, item)
fn(self, index)
_tidy(__delitem__)
return __delitem__
# Py2K
def __setslice__(fn):
def __setslice__(self, start, end, values):
for value in self[start:end]:
__del(self, value)
values = [__set(self, value) for value in values]
fn(self, start, end, values)
_tidy(__setslice__)
return __setslice__
def __delslice__(fn):
def __delslice__(self, start, end):
for value in self[start:end]:
__del(self, value)
fn(self, start, end)
_tidy(__delslice__)
return __delslice__
# end Py2K
def extend(fn):
def extend(self, iterable):
for value in iterable:
self.append(value)
_tidy(extend)
return extend
def __iadd__(fn):
def __iadd__(self, iterable):
# list.__iadd__ takes any iterable and seems to let TypeError raise
# as-is instead of returning NotImplemented
for value in iterable:
self.append(value)
return self
_tidy(__iadd__)
return __iadd__
def pop(fn):
def pop(self, index=-1):
__before_delete(self)
item = fn(self, index)
__del(self, item)
return item
_tidy(pop)
return pop
# __imul__ : not wrapping this. all members of the collection are already
# present, so no need to fire appends... wrapping it with an explicit
# decorator is still possible, so events on *= can be had if they're
# desired. hard to imagine a use case for __imul__, though.
l = locals().copy()
l.pop('_tidy')
return l
def _dict_decorators():
"""Tailored instrumentation wrappers for any dict-like mapping class."""
def _tidy(fn):
setattr(fn, '_sa_instrumented', True)
fn.__doc__ = getattr(getattr(dict, fn.__name__), '__doc__')
Unspecified = util.symbol('Unspecified')
def __setitem__(fn):
def __setitem__(self, key, value, _sa_initiator=None):
if key in self:
__del(self, self[key], _sa_initiator)
value = __set(self, value, _sa_initiator)
fn(self, key, value)
_tidy(__setitem__)
return __setitem__
def __delitem__(fn):
def __delitem__(self, key, _sa_initiator=None):
if key in self:
__del(self, self[key], _sa_initiator)
fn(self, key)
_tidy(__delitem__)
return __delitem__
def clear(fn):
def clear(self):
for key in self:
__del(self, self[key])
fn(self)
_tidy(clear)
return clear
def pop(fn):
def pop(self, key, default=Unspecified):
if key in self:
__del(self, self[key])
if default is Unspecified:
return fn(self, key)
else:
return fn(self, key, default)
_tidy(pop)
return pop
def popitem(fn):
def popitem(self):
__before_delete(self)
item = fn(self)
__del(self, item[1])
return item
_tidy(popitem)
return popitem
def setdefault(fn):
def setdefault(self, key, default=None):
if key not in self:
self.__setitem__(key, default)
return default
else:
return self.__getitem__(key)
_tidy(setdefault)
return setdefault
if sys.version_info < (2, 4):
def update(fn):
def update(self, other):
for key in other.keys():
if key not in self or self[key] is not other[key]:
self[key] = other[key]
_tidy(update)
return update
else:
def update(fn):
def update(self, __other=Unspecified, **kw):
if __other is not Unspecified:
if hasattr(__other, 'keys'):
for key in __other.keys():
if (key not in self or
self[key] is not __other[key]):
self[key] = __other[key]
else:
for key, value in __other:
if key not in self or self[key] is not value:
self[key] = value
for key in kw:
if key not in self or self[key] is not kw[key]:
self[key] = kw[key]
_tidy(update)
return update
l = locals().copy()
l.pop('_tidy')
l.pop('Unspecified')
return l
if util.py3k:
_set_binop_bases = (set, frozenset)
else:
import sets
_set_binop_bases = (set, frozenset, sets.BaseSet)
def _set_binops_check_strict(self, obj):
"""Allow only set, frozenset and self.__class__-derived objects in binops."""
return isinstance(obj, _set_binop_bases + (self.__class__,))
def _set_binops_check_loose(self, obj):
"""Allow anything set-like to participate in set binops."""
return (isinstance(obj, _set_binop_bases + (self.__class__,)) or
util.duck_type_collection(obj) == set)
def _set_decorators():
"""Tailored instrumentation wrappers for any set-like class."""
def _tidy(fn):
setattr(fn, '_sa_instrumented', True)
fn.__doc__ = getattr(getattr(set, fn.__name__), '__doc__')
Unspecified = util.symbol('Unspecified')
def add(fn):
def add(self, value, _sa_initiator=None):
if value not in self:
value = __set(self, value, _sa_initiator)
# testlib.pragma exempt:__hash__
fn(self, value)
_tidy(add)
return add
if sys.version_info < (2, 4):
def discard(fn):
def discard(self, value, _sa_initiator=None):
if value in self:
self.remove(value, _sa_initiator)
_tidy(discard)
return discard
else:
def discard(fn):
def discard(self, value, _sa_initiator=None):
# testlib.pragma exempt:__hash__
if value in self:
__del(self, value, _sa_initiator)
# testlib.pragma exempt:__hash__
fn(self, value)
_tidy(discard)
return discard
def remove(fn):
def remove(self, value, _sa_initiator=None):
# testlib.pragma exempt:__hash__
if value in self:
__del(self, value, _sa_initiator)
# testlib.pragma exempt:__hash__
fn(self, value)
_tidy(remove)
return remove
def pop(fn):
def pop(self):
__before_delete(self)
item = fn(self)
__del(self, item)
return item
_tidy(pop)
return pop
def clear(fn):
def clear(self):
for item in list(self):
self.remove(item)
_tidy(clear)
return clear
def update(fn):
def update(self, value):
for item in value:
self.add(item)
_tidy(update)
return update
def __ior__(fn):
def __ior__(self, value):
if not _set_binops_check_strict(self, value):
return NotImplemented
for item in value:
self.add(item)
return self
_tidy(__ior__)
return __ior__
def difference_update(fn):
def difference_update(self, value):
for item in value:
self.discard(item)
_tidy(difference_update)
return difference_update
def __isub__(fn):
def __isub__(self, value):
if not _set_binops_check_strict(self, value):
return NotImplemented
for item in value:
self.discard(item)
return self
_tidy(__isub__)
return __isub__
def intersection_update(fn):
def intersection_update(self, other):
want, have = self.intersection(other), set(self)
remove, add = have - want, want - have
for item in remove:
self.remove(item)
for item in add:
self.add(item)
_tidy(intersection_update)
return intersection_update
def __iand__(fn):
def __iand__(self, other):
if not _set_binops_check_strict(self, other):
return NotImplemented
want, have = self.intersection(other), set(self)
remove, add = have - want, want - have
for item in remove:
self.remove(item)
for item in add:
self.add(item)
return self
_tidy(__iand__)
return __iand__
def symmetric_difference_update(fn):
def symmetric_difference_update(self, other):
want, have = self.symmetric_difference(other), set(self)
remove, add = have - want, want - have
for item in remove:
self.remove(item)
for item in add:
self.add(item)
_tidy(symmetric_difference_update)
return symmetric_difference_update
def __ixor__(fn):
def __ixor__(self, other):
if not _set_binops_check_strict(self, other):
return NotImplemented
want, have = self.symmetric_difference(other), set(self)
remove, add = have - want, want - have
for item in remove:
self.remove(item)
for item in add:
self.add(item)
return self
_tidy(__ixor__)
return __ixor__
l = locals().copy()
l.pop('_tidy')
l.pop('Unspecified')
return l
class InstrumentedList(list):
"""An instrumented version of the built-in list."""
__instrumentation__ = {
'appender': 'append',
'remover': 'remove',
'iterator': '__iter__', }
class InstrumentedSet(set):
"""An instrumented version of the built-in set."""
__instrumentation__ = {
'appender': 'add',
'remover': 'remove',
'iterator': '__iter__', }
class InstrumentedDict(dict):
"""An instrumented version of the built-in dict."""
# Py3K
#__instrumentation__ = {
# 'iterator': 'values', }
# Py2K
__instrumentation__ = {
'iterator': 'itervalues', }
# end Py2K
__canned_instrumentation = {
list: InstrumentedList,
set: InstrumentedSet,
dict: InstrumentedDict,
}
__interfaces = {
list: {'appender': 'append',
'remover': 'remove',
'iterator': '__iter__',
'_decorators': _list_decorators(), },
set: {'appender': 'add',
'remover': 'remove',
'iterator': '__iter__',
'_decorators': _set_decorators(), },
# decorators are required for dicts and object collections.
# Py3K
#dict: {'iterator': 'values',
# '_decorators': _dict_decorators(), },
# Py2K
dict: {'iterator': 'itervalues',
'_decorators': _dict_decorators(), },
# end Py2K
# < 0.4 compatible naming, deprecated- use decorators instead.
None: {}
}
class MappedCollection(dict):
"""A basic dictionary-based collection class.
Extends dict with the minimal bag semantics that collection classes require.
``set`` and ``remove`` are implemented in terms of a keying function: any
callable that takes an object and returns an object for use as a dictionary
key.
"""
def __init__(self, keyfunc):
"""Create a new collection with keying provided by keyfunc.
keyfunc may be any callable any callable that takes an object and
returns an object for use as a dictionary key.
The keyfunc will be called every time the ORM needs to add a member by
value-only (such as when loading instances from the database) or
remove a member. The usual cautions about dictionary keying apply-
``keyfunc(object)`` should return the same output for the life of the
collection. Keying based on mutable properties can result in
unreachable instances "lost" in the collection.
"""
self.keyfunc = keyfunc
def set(self, value, _sa_initiator=None):
"""Add an item by value, consulting the keyfunc for the key."""
key = self.keyfunc(value)
self.__setitem__(key, value, _sa_initiator)
set = collection.internally_instrumented(set)
set = collection.appender(set)
def remove(self, value, _sa_initiator=None):
"""Remove an item by value, consulting the keyfunc for the key."""
key = self.keyfunc(value)
# Let self[key] raise if key is not in this collection
# testlib.pragma exempt:__ne__
if self[key] != value:
raise sa_exc.InvalidRequestError(
"Can not remove '%s': collection holds '%s' for key '%s'. "
"Possible cause: is the MappedCollection key function "
"based on mutable properties or properties that only obtain "
"values after flush?" %
(value, self[key], key))
self.__delitem__(key, _sa_initiator)
remove = collection.internally_instrumented(remove)
remove = collection.remover(remove)
def _convert(self, dictlike):
"""Validate and convert a dict-like object into values for set()ing.
This is called behind the scenes when a MappedCollection is replaced
entirely by another collection, as in::
myobj.mappedcollection = {'a':obj1, 'b': obj2} # ...
Raises a TypeError if the key in any (key, value) pair in the dictlike
object does not match the key that this collection's keyfunc would
have assigned for that value.
"""
for incoming_key, value in util.dictlike_iteritems(dictlike):
new_key = self.keyfunc(value)
if incoming_key != new_key:
raise TypeError(
"Found incompatible key %r for value %r; this collection's "
"keying function requires a key of %r for this value." % (
incoming_key, value, new_key))
yield value
_convert = collection.converter(_convert)
|