File size: 32,462 Bytes
9c6594c
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
import copy
import sys
from abc import ABC, abstractmethod
from collections import defaultdict
from dataclasses import dataclass, field
from enum import Enum
from typing import Any, Dict, Iterator, List, Optional, Set, Tuple, Type, Union

from antlr4 import ParserRuleContext

from ._utils import (
    _DEFAULT_MARKER_,
    NoneType,
    ValueKind,
    _get_value,
    _is_interpolation,
    _is_missing_value,
    _is_special,
    format_and_raise,
    get_value_kind,
    is_union_annotation,
    is_valid_value_annotation,
    split_key,
    type_str,
)
from .errors import (
    ConfigKeyError,
    ConfigTypeError,
    InterpolationKeyError,
    InterpolationResolutionError,
    InterpolationToMissingValueError,
    InterpolationValidationError,
    MissingMandatoryValue,
    UnsupportedInterpolationType,
    ValidationError,
)
from .grammar.gen.OmegaConfGrammarParser import OmegaConfGrammarParser
from .grammar_parser import parse
from .grammar_visitor import GrammarVisitor

DictKeyType = Union[str, bytes, int, Enum, float, bool]


@dataclass
class Metadata:

    ref_type: Union[Type[Any], Any]

    object_type: Union[Type[Any], Any]

    optional: bool

    key: Any

    # Flags have 3 modes:
    #   unset : inherit from parent (None if no parent specifies)
    #   set to true: flag is true
    #   set to false: flag is false
    flags: Optional[Dict[str, bool]] = None

    # If True, when checking the value of a flag, if the flag is not set None is returned
    # otherwise, the parent node is queried.
    flags_root: bool = False

    resolver_cache: Dict[str, Any] = field(default_factory=lambda: defaultdict(dict))

    def __post_init__(self) -> None:
        if self.flags is None:
            self.flags = {}

    @property
    def type_hint(self) -> Union[Type[Any], Any]:
        """Compute `type_hint` from `self.optional` and `self.ref_type`"""
        # For compatibility with pickled OmegaConf objects created using older
        # versions of OmegaConf, we store `ref_type` and `object_type`
        # separately (rather than storing `type_hint` directly).
        if self.optional:
            return Optional[self.ref_type]
        else:
            return self.ref_type


@dataclass
class ContainerMetadata(Metadata):
    key_type: Any = None
    element_type: Any = None

    def __post_init__(self) -> None:
        if self.ref_type is None:
            self.ref_type = Any
        assert self.key_type is Any or isinstance(self.key_type, type)
        if self.element_type is not None:
            if not is_valid_value_annotation(self.element_type):
                raise ValidationError(
                    f"Unsupported value type: '{type_str(self.element_type, include_module_name=True)}'"
                )

        if self.flags is None:
            self.flags = {}


class Node(ABC):
    _metadata: Metadata

    _parent: Optional["Box"]
    _flags_cache: Optional[Dict[str, Optional[bool]]]

    def __init__(self, parent: Optional["Box"], metadata: Metadata):
        self.__dict__["_metadata"] = metadata
        self.__dict__["_parent"] = parent
        self.__dict__["_flags_cache"] = None

    def __getstate__(self) -> Dict[str, Any]:
        # Overridden to ensure that the flags cache is cleared on serialization.
        state_dict = copy.copy(self.__dict__)
        del state_dict["_flags_cache"]
        return state_dict

    def __setstate__(self, state_dict: Dict[str, Any]) -> None:
        self.__dict__.update(state_dict)
        self.__dict__["_flags_cache"] = None

    def _set_parent(self, parent: Optional["Box"]) -> None:
        assert parent is None or isinstance(parent, Box)
        self.__dict__["_parent"] = parent
        self._invalidate_flags_cache()

    def _invalidate_flags_cache(self) -> None:
        self.__dict__["_flags_cache"] = None

    def _get_parent(self) -> Optional["Box"]:
        parent = self.__dict__["_parent"]
        assert parent is None or isinstance(parent, Box)
        return parent

    def _get_parent_container(self) -> Optional["Container"]:
        """
        Like _get_parent, but returns the grandparent
        in the case where `self` is wrapped by a UnionNode.
        """
        parent = self.__dict__["_parent"]
        assert parent is None or isinstance(parent, Box)

        if isinstance(parent, UnionNode):
            grandparent = parent.__dict__["_parent"]
            assert grandparent is None or isinstance(grandparent, Container)
            return grandparent
        else:
            assert parent is None or isinstance(parent, Container)
            return parent

    def _set_flag(
        self,
        flags: Union[List[str], str],
        values: Union[List[Optional[bool]], Optional[bool]],
    ) -> "Node":
        if isinstance(flags, str):
            flags = [flags]

        if values is None or isinstance(values, bool):
            values = [values]

        if len(values) == 1:
            values = len(flags) * values

        if len(flags) != len(values):
            raise ValueError("Inconsistent lengths of input flag names and values")

        for idx, flag in enumerate(flags):
            value = values[idx]
            if value is None:
                assert self._metadata.flags is not None
                if flag in self._metadata.flags:
                    del self._metadata.flags[flag]
            else:
                assert self._metadata.flags is not None
                self._metadata.flags[flag] = value
        self._invalidate_flags_cache()
        return self

    def _get_node_flag(self, flag: str) -> Optional[bool]:
        """
        :param flag: flag to inspect
        :return: the state of the flag on this node.
        """
        assert self._metadata.flags is not None
        return self._metadata.flags.get(flag)

    def _get_flag(self, flag: str) -> Optional[bool]:
        cache = self.__dict__["_flags_cache"]
        if cache is None:
            cache = self.__dict__["_flags_cache"] = {}

        ret = cache.get(flag, _DEFAULT_MARKER_)
        if ret is _DEFAULT_MARKER_:
            ret = self._get_flag_no_cache(flag)
            cache[flag] = ret
        assert ret is None or isinstance(ret, bool)
        return ret

    def _get_flag_no_cache(self, flag: str) -> Optional[bool]:
        """
        Returns True if this config node flag is set
        A flag is set if node.set_flag(True) was called
        or one if it's parents is flag is set
        :return:
        """
        flags = self._metadata.flags
        assert flags is not None
        if flag in flags and flags[flag] is not None:
            return flags[flag]

        if self._is_flags_root():
            return None

        parent = self._get_parent()
        if parent is None:
            return None
        else:
            # noinspection PyProtectedMember
            return parent._get_flag(flag)

    def _format_and_raise(
        self,
        key: Any,
        value: Any,
        cause: Exception,
        msg: Optional[str] = None,
        type_override: Any = None,
    ) -> None:
        format_and_raise(
            node=self,
            key=key,
            value=value,
            msg=str(cause) if msg is None else msg,
            cause=cause,
            type_override=type_override,
        )
        assert False

    @abstractmethod
    def _get_full_key(self, key: Optional[Union[DictKeyType, int]]) -> str:
        ...

    def _dereference_node(self) -> "Node":
        node = self._dereference_node_impl(throw_on_resolution_failure=True)
        assert node is not None
        return node

    def _maybe_dereference_node(
        self,
        throw_on_resolution_failure: bool = False,
        memo: Optional[Set[int]] = None,
    ) -> Optional["Node"]:
        return self._dereference_node_impl(
            throw_on_resolution_failure=throw_on_resolution_failure,
            memo=memo,
        )

    def _dereference_node_impl(
        self,
        throw_on_resolution_failure: bool,
        memo: Optional[Set[int]] = None,
    ) -> Optional["Node"]:
        if not self._is_interpolation():
            return self

        parent = self._get_parent_container()
        if parent is None:
            if throw_on_resolution_failure:
                raise InterpolationResolutionError(
                    "Cannot resolve interpolation for a node without a parent"
                )
            return None
        assert parent is not None
        key = self._key()
        return parent._resolve_interpolation_from_parse_tree(
            parent=parent,
            key=key,
            value=self,
            parse_tree=parse(_get_value(self)),
            throw_on_resolution_failure=throw_on_resolution_failure,
            memo=memo,
        )

    def _get_root(self) -> "Container":
        root: Optional[Box] = self._get_parent()
        if root is None:
            assert isinstance(self, Container)
            return self
        assert root is not None and isinstance(root, Box)
        while root._get_parent() is not None:
            root = root._get_parent()
            assert root is not None and isinstance(root, Box)
        assert root is not None and isinstance(root, Container)
        return root

    def _is_missing(self) -> bool:
        """
        Check if the node's value is `???` (does *not* resolve interpolations).
        """
        return _is_missing_value(self)

    def _is_none(self) -> bool:
        """
        Check if the node's value is `None` (does *not* resolve interpolations).
        """
        return self._value() is None

    @abstractmethod
    def __eq__(self, other: Any) -> bool:
        ...

    @abstractmethod
    def __ne__(self, other: Any) -> bool:
        ...

    @abstractmethod
    def __hash__(self) -> int:
        ...

    @abstractmethod
    def _value(self) -> Any:
        ...

    @abstractmethod
    def _set_value(self, value: Any, flags: Optional[Dict[str, bool]] = None) -> None:
        ...

    @abstractmethod
    def _is_optional(self) -> bool:
        ...

    @abstractmethod
    def _is_interpolation(self) -> bool:
        ...

    def _key(self) -> Any:
        return self._metadata.key

    def _set_key(self, key: Any) -> None:
        self._metadata.key = key

    def _is_flags_root(self) -> bool:
        return self._metadata.flags_root

    def _set_flags_root(self, flags_root: bool) -> None:
        if self._metadata.flags_root != flags_root:
            self._metadata.flags_root = flags_root
            self._invalidate_flags_cache()

    def _has_ref_type(self) -> bool:
        return self._metadata.ref_type is not Any


class Box(Node):
    """
    Base class for nodes that can contain other nodes.
    Concrete subclasses include DictConfig, ListConfig, and UnionNode.
    """

    _content: Any

    def __init__(self, parent: Optional["Box"], metadata: Metadata):
        super().__init__(parent=parent, metadata=metadata)
        self.__dict__["_content"] = None

    def __copy__(self) -> Any:
        # real shallow copy is impossible because of the reference to the parent.
        return copy.deepcopy(self)

    def _re_parent(self) -> None:
        from .dictconfig import DictConfig
        from .listconfig import ListConfig

        # update parents of first level Config nodes to self

        if isinstance(self, DictConfig):
            content = self.__dict__["_content"]
            if isinstance(content, dict):
                for _key, value in self.__dict__["_content"].items():
                    if value is not None:
                        value._set_parent(self)
                    if isinstance(value, Box):
                        value._re_parent()
        elif isinstance(self, ListConfig):
            content = self.__dict__["_content"]
            if isinstance(content, list):
                for item in self.__dict__["_content"]:
                    if item is not None:
                        item._set_parent(self)
                    if isinstance(item, Box):
                        item._re_parent()
        elif isinstance(self, UnionNode):
            content = self.__dict__["_content"]
            if isinstance(content, Node):
                content._set_parent(self)
                if isinstance(content, Box):  # pragma: no cover
                    # No coverage here as support for containers inside
                    # UnionNode is not yet implemented
                    content._re_parent()


class Container(Box):
    """
    Container tagging interface
    """

    _metadata: ContainerMetadata

    @abstractmethod
    def _get_child(
        self,
        key: Any,
        validate_access: bool = True,
        validate_key: bool = True,
        throw_on_missing_value: bool = False,
        throw_on_missing_key: bool = False,
    ) -> Union[Optional[Node], List[Optional[Node]]]:
        ...

    @abstractmethod
    def _get_node(
        self,
        key: Any,
        validate_access: bool = True,
        validate_key: bool = True,
        throw_on_missing_value: bool = False,
        throw_on_missing_key: bool = False,
    ) -> Union[Optional[Node], List[Optional[Node]]]:
        ...

    @abstractmethod
    def __delitem__(self, key: Any) -> None:
        ...

    @abstractmethod
    def __setitem__(self, key: Any, value: Any) -> None:
        ...

    @abstractmethod
    def __iter__(self) -> Iterator[Any]:
        ...

    @abstractmethod
    def __getitem__(self, key_or_index: Any) -> Any:
        ...

    def _resolve_key_and_root(self, key: str) -> Tuple["Container", str]:
        orig = key
        if not key.startswith("."):
            return self._get_root(), key
        else:
            root: Optional[Container] = self
            assert key.startswith(".")
            while True:
                assert root is not None
                key = key[1:]
                if not key.startswith("."):
                    break
                root = root._get_parent_container()
                if root is None:
                    raise ConfigKeyError(f"Error resolving key '{orig}'")

            return root, key

    def _select_impl(
        self,
        key: str,
        throw_on_missing: bool,
        throw_on_resolution_failure: bool,
        memo: Optional[Set[int]] = None,
    ) -> Tuple[Optional["Container"], Optional[str], Optional[Node]]:
        """
        Select a value using dot separated key sequence
        """
        from .omegaconf import _select_one

        if key == "":
            return self, "", self

        split = split_key(key)
        root: Optional[Container] = self
        for i in range(len(split) - 1):
            if root is None:
                break

            k = split[i]
            ret, _ = _select_one(
                c=root,
                key=k,
                throw_on_missing=throw_on_missing,
                throw_on_type_error=throw_on_resolution_failure,
            )
            if isinstance(ret, Node):
                ret = ret._maybe_dereference_node(
                    throw_on_resolution_failure=throw_on_resolution_failure,
                    memo=memo,
                )

            if ret is not None and not isinstance(ret, Container):
                parent_key = ".".join(split[0 : i + 1])
                child_key = split[i + 1]
                raise ConfigTypeError(
                    f"Error trying to access {key}: node `{parent_key}` "
                    f"is not a container and thus cannot contain `{child_key}`"
                )
            root = ret

        if root is None:
            return None, None, None

        last_key = split[-1]
        value, _ = _select_one(
            c=root,
            key=last_key,
            throw_on_missing=throw_on_missing,
            throw_on_type_error=throw_on_resolution_failure,
        )
        if value is None:
            return root, last_key, None

        if memo is not None:
            vid = id(value)
            if vid in memo:
                raise InterpolationResolutionError("Recursive interpolation detected")
            # push to memo "stack"
            memo.add(vid)

        try:
            value = root._maybe_resolve_interpolation(
                parent=root,
                key=last_key,
                value=value,
                throw_on_resolution_failure=throw_on_resolution_failure,
                memo=memo,
            )
        finally:
            if memo is not None:
                # pop from memo "stack"
                memo.remove(vid)

        return root, last_key, value

    def _resolve_interpolation_from_parse_tree(
        self,
        parent: Optional["Container"],
        value: "Node",
        key: Any,
        parse_tree: OmegaConfGrammarParser.ConfigValueContext,
        throw_on_resolution_failure: bool,
        memo: Optional[Set[int]],
    ) -> Optional["Node"]:
        """
        Resolve an interpolation.

        This happens in two steps:
            1. The parse tree is visited, which outputs either a `Node` (e.g.,
               for node interpolations "${foo}"), a string (e.g., for string
               interpolations "hello ${name}", or any other arbitrary value
               (e.g., or custom interpolations "${foo:bar}").
            2. This output is potentially validated and converted when the node
               being resolved (`value`) is typed.

        If an error occurs in one of the above steps, an `InterpolationResolutionError`
        (or a subclass of it) is raised, *unless* `throw_on_resolution_failure` is set
        to `False` (in which case the return value is `None`).

        :param parent: Parent of the node being resolved.
        :param value: Node being resolved.
        :param key: The associated key in the parent.
        :param parse_tree: The parse tree as obtained from `grammar_parser.parse()`.
        :param throw_on_resolution_failure: If `False`, then exceptions raised during
            the resolution of the interpolation are silenced, and instead `None` is
            returned.

        :return: A `Node` that contains the interpolation result. This may be an existing
            node in the config (in the case of a node interpolation "${foo}"), or a new
            node that is created to wrap the interpolated value. It is `None` if and only if
            `throw_on_resolution_failure` is `False` and an error occurs during resolution.
        """

        try:
            resolved = self.resolve_parse_tree(
                parse_tree=parse_tree, node=value, key=key, memo=memo
            )
        except InterpolationResolutionError:
            if throw_on_resolution_failure:
                raise
            return None

        return self._validate_and_convert_interpolation_result(
            parent=parent,
            value=value,
            key=key,
            resolved=resolved,
            throw_on_resolution_failure=throw_on_resolution_failure,
        )

    def _validate_and_convert_interpolation_result(
        self,
        parent: Optional["Container"],
        value: "Node",
        key: Any,
        resolved: Any,
        throw_on_resolution_failure: bool,
    ) -> Optional["Node"]:
        from .nodes import AnyNode, InterpolationResultNode, ValueNode

        # If the output is not a Node already (e.g., because it is the output of a
        # custom resolver), then we will need to wrap it within a Node.
        must_wrap = not isinstance(resolved, Node)

        # If the node is typed, validate (and possibly convert) the result.
        if isinstance(value, ValueNode) and not isinstance(value, AnyNode):
            res_value = _get_value(resolved)
            try:
                conv_value = value.validate_and_convert(res_value)
            except ValidationError as e:
                if throw_on_resolution_failure:
                    self._format_and_raise(
                        key=key,
                        value=res_value,
                        cause=e,
                        msg=f"While dereferencing interpolation '{value}': {e}",
                        type_override=InterpolationValidationError,
                    )
                return None

            # If the converted value is of the same type, it means that no conversion
            # was actually needed. As a result, we can keep the original `resolved`
            # (and otherwise, the converted value must be wrapped into a new node).
            if type(conv_value) != type(res_value):
                must_wrap = True
                resolved = conv_value

        if must_wrap:
            return InterpolationResultNode(value=resolved, key=key, parent=parent)
        else:
            assert isinstance(resolved, Node)
            return resolved

    def _validate_not_dereferencing_to_parent(self, node: Node, target: Node) -> None:
        parent: Optional[Node] = node
        while parent is not None:
            if parent is target:
                raise InterpolationResolutionError(
                    "Interpolation to parent node detected"
                )
            parent = parent._get_parent()

    def _resolve_node_interpolation(
        self, inter_key: str, memo: Optional[Set[int]]
    ) -> "Node":
        """A node interpolation is of the form `${foo.bar}`"""
        try:
            root_node, inter_key = self._resolve_key_and_root(inter_key)
        except ConfigKeyError as exc:
            raise InterpolationKeyError(
                f"ConfigKeyError while resolving interpolation: {exc}"
            ).with_traceback(sys.exc_info()[2])

        try:
            parent, last_key, value = root_node._select_impl(
                inter_key,
                throw_on_missing=True,
                throw_on_resolution_failure=True,
                memo=memo,
            )
        except MissingMandatoryValue as exc:
            raise InterpolationToMissingValueError(
                f"MissingMandatoryValue while resolving interpolation: {exc}"
            ).with_traceback(sys.exc_info()[2])

        if parent is None or value is None:
            raise InterpolationKeyError(f"Interpolation key '{inter_key}' not found")
        else:
            self._validate_not_dereferencing_to_parent(node=self, target=value)
            return value

    def _evaluate_custom_resolver(
        self,
        key: Any,
        node: Node,
        inter_type: str,
        inter_args: Tuple[Any, ...],
        inter_args_str: Tuple[str, ...],
    ) -> Any:
        from omegaconf import OmegaConf

        resolver = OmegaConf._get_resolver(inter_type)
        if resolver is not None:
            root_node = self._get_root()
            return resolver(
                root_node,
                self,
                node,
                inter_args,
                inter_args_str,
            )
        else:
            raise UnsupportedInterpolationType(
                f"Unsupported interpolation type {inter_type}"
            )

    def _maybe_resolve_interpolation(
        self,
        parent: Optional["Container"],
        key: Any,
        value: Node,
        throw_on_resolution_failure: bool,
        memo: Optional[Set[int]] = None,
    ) -> Optional[Node]:
        value_kind = get_value_kind(value)
        if value_kind != ValueKind.INTERPOLATION:
            return value

        parse_tree = parse(_get_value(value))
        return self._resolve_interpolation_from_parse_tree(
            parent=parent,
            value=value,
            key=key,
            parse_tree=parse_tree,
            throw_on_resolution_failure=throw_on_resolution_failure,
            memo=memo if memo is not None else set(),
        )

    def resolve_parse_tree(
        self,
        parse_tree: ParserRuleContext,
        node: Node,
        memo: Optional[Set[int]] = None,
        key: Optional[Any] = None,
    ) -> Any:
        """
        Resolve a given parse tree into its value.

        We make no assumption here on the type of the tree's root, so that the
        return value may be of any type.
        """

        def node_interpolation_callback(
            inter_key: str, memo: Optional[Set[int]]
        ) -> Optional["Node"]:
            return self._resolve_node_interpolation(inter_key=inter_key, memo=memo)

        def resolver_interpolation_callback(
            name: str, args: Tuple[Any, ...], args_str: Tuple[str, ...]
        ) -> Any:
            return self._evaluate_custom_resolver(
                key=key,
                node=node,
                inter_type=name,
                inter_args=args,
                inter_args_str=args_str,
            )

        visitor = GrammarVisitor(
            node_interpolation_callback=node_interpolation_callback,
            resolver_interpolation_callback=resolver_interpolation_callback,
            memo=memo,
        )
        try:
            return visitor.visit(parse_tree)
        except InterpolationResolutionError:
            raise
        except Exception as exc:
            # Other kinds of exceptions are wrapped in an `InterpolationResolutionError`.
            raise InterpolationResolutionError(
                f"{type(exc).__name__} raised while resolving interpolation: {exc}"
            ).with_traceback(sys.exc_info()[2])

    def _invalidate_flags_cache(self) -> None:
        from .dictconfig import DictConfig
        from .listconfig import ListConfig

        # invalidate subtree cache only if the cache is initialized in this node.

        if self.__dict__["_flags_cache"] is not None:
            self.__dict__["_flags_cache"] = None
            if isinstance(self, DictConfig):
                content = self.__dict__["_content"]
                if isinstance(content, dict):
                    for value in self.__dict__["_content"].values():
                        value._invalidate_flags_cache()
            elif isinstance(self, ListConfig):
                content = self.__dict__["_content"]
                if isinstance(content, list):
                    for item in self.__dict__["_content"]:
                        item._invalidate_flags_cache()


class SCMode(Enum):
    DICT = 1  # Convert to plain dict
    DICT_CONFIG = 2  # Keep as OmegaConf DictConfig
    INSTANTIATE = 3  # Create a dataclass or attrs class instance


class UnionNode(Box):
    """
    This class handles Union type hints. The `_content` attribute is either a
    child node that is compatible with the given Union ref_type, or it is a
    special value (None or MISSING or interpolation).

    Much of the logic for e.g. value assignment and type validation is
    delegated to the child node. As such, UnionNode functions as a
    "pass-through" node. User apps and downstream libraries should not need to
    know about UnionNode (assuming they only use OmegaConf's public API).
    """

    _parent: Optional[Container]
    _content: Union[Node, None, str]

    def __init__(
        self,
        content: Any,
        ref_type: Any,
        is_optional: bool = True,
        key: Any = None,
        parent: Optional[Box] = None,
    ) -> None:
        try:
            if not is_union_annotation(ref_type):  # pragma: no cover
                msg = (
                    f"UnionNode got unexpected ref_type {ref_type}. Please file a bug"
                    + " report at https://github.com/omry/omegaconf/issues"
                )
                raise AssertionError(msg)
            if not isinstance(parent, (Container, NoneType)):
                raise ConfigTypeError("Parent type is not omegaconf.Container")
            super().__init__(
                parent=parent,
                metadata=Metadata(
                    ref_type=ref_type,
                    object_type=None,
                    optional=is_optional,
                    key=key,
                    flags={"convert": False},
                ),
            )
            self._set_value(content)
        except Exception as ex:
            format_and_raise(node=None, key=key, value=content, msg=str(ex), cause=ex)

    def _get_full_key(self, key: Optional[Union[DictKeyType, int]]) -> str:
        parent = self._get_parent()
        if parent is None:
            if self._metadata.key is None:
                return ""
            else:
                return str(self._metadata.key)
        else:
            return parent._get_full_key(self._metadata.key)

    def __eq__(self, other: Any) -> bool:
        content = self.__dict__["_content"]
        if isinstance(content, Node):
            ret = content.__eq__(other)
        elif isinstance(other, Node):
            ret = other.__eq__(content)
        else:
            ret = content.__eq__(other)
        assert isinstance(ret, (bool, type(NotImplemented)))
        return ret

    def __ne__(self, other: Any) -> bool:
        x = self.__eq__(other)
        if x is NotImplemented:
            return NotImplemented
        return not x

    def __hash__(self) -> int:
        return hash(self.__dict__["_content"])

    def _value(self) -> Union[Node, None, str]:
        content = self.__dict__["_content"]
        assert isinstance(content, (Node, NoneType, str))
        return content

    def _set_value(self, value: Any, flags: Optional[Dict[str, bool]] = None) -> None:
        previous_content = self.__dict__["_content"]
        previous_metadata = self.__dict__["_metadata"]
        try:
            self._set_value_impl(value, flags)
        except Exception as e:
            self.__dict__["_content"] = previous_content
            self.__dict__["_metadata"] = previous_metadata
            raise e

    def _set_value_impl(
        self, value: Any, flags: Optional[Dict[str, bool]] = None
    ) -> None:
        from omegaconf.omegaconf import _node_wrap

        ref_type = self._metadata.ref_type
        type_hint = self._metadata.type_hint

        value = _get_value(value)
        if _is_special(value):
            assert isinstance(value, (str, NoneType))
            if value is None:
                if not self._is_optional():
                    raise ValidationError(
                        f"Value '$VALUE' is incompatible with type hint '{type_str(type_hint)}'"
                    )
            self.__dict__["_content"] = value
        elif isinstance(value, Container):
            raise ValidationError(
                f"Cannot assign container '$VALUE' of type '$VALUE_TYPE' to {type_str(type_hint)}"
            )
        else:
            for candidate_ref_type in ref_type.__args__:
                try:
                    self.__dict__["_content"] = _node_wrap(
                        value=value,
                        ref_type=candidate_ref_type,
                        is_optional=False,
                        key=None,
                        parent=self,
                    )
                    break
                except ValidationError:
                    continue
            else:
                raise ValidationError(
                    f"Value '$VALUE' of type '$VALUE_TYPE' is incompatible with type hint '{type_str(type_hint)}'"
                )

    def _is_optional(self) -> bool:
        return self.__dict__["_metadata"].optional is True

    def _is_interpolation(self) -> bool:
        return _is_interpolation(self.__dict__["_content"])

    def __str__(self) -> str:
        return str(self.__dict__["_content"])

    def __repr__(self) -> str:
        return repr(self.__dict__["_content"])

    def __deepcopy__(self, memo: Dict[int, Any]) -> "UnionNode":
        res = object.__new__(type(self))
        for key, value in self.__dict__.items():
            if key not in ("_content", "_parent"):
                res.__dict__[key] = copy.deepcopy(value, memo=memo)

        src_content = self.__dict__["_content"]
        if isinstance(src_content, Node):
            old_parent = src_content.__dict__["_parent"]
            try:
                src_content.__dict__["_parent"] = None
                content_copy = copy.deepcopy(src_content, memo=memo)
                content_copy.__dict__["_parent"] = res
            finally:
                src_content.__dict__["_parent"] = old_parent
        else:
            # None and strings can be assigned as is
            content_copy = src_content

        res.__dict__["_content"] = content_copy
        res.__dict__["_parent"] = self.__dict__["_parent"]
        return res