podman

1
// Copyright (C) MongoDB, Inc. 2022-present.
2
//
3
// Licensed under the Apache License, Version 2.0 (the "License"); you may
4
// not use this file except in compliance with the License. You may obtain
5
// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
6

7
// Package bsoncodec provides a system for encoding values to BSON representations and decoding
8
// values from BSON representations. This package considers both binary BSON and ExtendedJSON as
9
// BSON representations. The types in this package enable a flexible system for handling this
10
// encoding and decoding.
11
//
12
// The codec system is composed of two parts:
13
//
14
// 1) ValueEncoders and ValueDecoders that handle encoding and decoding Go values to and from BSON
15
// representations.
16
//
17
// 2) A Registry that holds these ValueEncoders and ValueDecoders and provides methods for
18
// retrieving them.
19
//
20
// # ValueEncoders and ValueDecoders
21
//
22
// The ValueEncoder interface is implemented by types that can encode a provided Go type to BSON.
23
// The value to encode is provided as a reflect.Value and a bsonrw.ValueWriter is used within the
24
// EncodeValue method to actually create the BSON representation. For convenience, ValueEncoderFunc
25
// is provided to allow use of a function with the correct signature as a ValueEncoder. An
26
// EncodeContext instance is provided to allow implementations to lookup further ValueEncoders and
27
// to provide configuration information.
28
//
29
// The ValueDecoder interface is the inverse of the ValueEncoder. Implementations should ensure that
30
// the value they receive is settable. Similar to ValueEncoderFunc, ValueDecoderFunc is provided to
31
// allow the use of a function with the correct signature as a ValueDecoder. A DecodeContext
32
// instance is provided and serves similar functionality to the EncodeContext.
33
//
34
// # Registry and RegistryBuilder
35
//
36
// A Registry is an immutable store for ValueEncoders, ValueDecoders, and a type map. See the Registry type
37
// documentation for examples of registering various custom encoders and decoders. A Registry can be constructed using a
38
// RegistryBuilder, which handles three main types of codecs:
39
//
40
// 1. Type encoders/decoders - These can be registered using the RegisterTypeEncoder and RegisterTypeDecoder methods.
41
// The registered codec will be invoked when encoding/decoding a value whose type matches the registered type exactly.
42
// If the registered type is an interface, the codec will be invoked when encoding or decoding values whose type is the
43
// interface, but not for values with concrete types that implement the interface.
44
//
45
// 2. Hook encoders/decoders - These can be registered using the RegisterHookEncoder and RegisterHookDecoder methods.
46
// These methods only accept interface types and the registered codecs will be invoked when encoding or decoding values
47
// whose types implement the interface. An example of a hook defined by the driver is bson.Marshaler. The driver will
48
// call the MarshalBSON method for any value whose type implements bson.Marshaler, regardless of the value's concrete
49
// type.
50
//
51
// 3. Type map entries - This can be used to associate a BSON type with a Go type. These type associations are used when
52
// decoding into a bson.D/bson.M or a struct field of type interface{}. For example, by default, BSON int32 and int64
53
// values decode as Go int32 and int64 instances, respectively, when decoding into a bson.D. The following code would
54
// change the behavior so these values decode as Go int instances instead:
55
//
56
//	intType := reflect.TypeOf(int(0))
57
//	registryBuilder.RegisterTypeMapEntry(bsontype.Int32, intType).RegisterTypeMapEntry(bsontype.Int64, intType)
58
//
59
// 4. Kind encoder/decoders - These can be registered using the RegisterDefaultEncoder and RegisterDefaultDecoder
60
// methods. The registered codec will be invoked when encoding or decoding values whose reflect.Kind matches the
61
// registered reflect.Kind as long as the value's type doesn't match a registered type or hook encoder/decoder first.
62
// These methods should be used to change the behavior for all values for a specific kind.
63
//
64
// # Registry Lookup Procedure
65
//
66
// When looking up an encoder in a Registry, the precedence rules are as follows:
67
//
68
// 1. A type encoder registered for the exact type of the value.
69
//
70
// 2. A hook encoder registered for an interface that is implemented by the value or by a pointer to the value. If the
71
// value matches multiple hooks (e.g. the type implements bsoncodec.Marshaler and bsoncodec.ValueMarshaler), the first
72
// one registered will be selected. Note that registries constructed using bson.NewRegistryBuilder have driver-defined
73
// hooks registered for the bsoncodec.Marshaler, bsoncodec.ValueMarshaler, and bsoncodec.Proxy interfaces, so those
74
// will take precedence over any new hooks.
75
//
76
// 3. A kind encoder registered for the value's kind.
77
//
78
// If all of these lookups fail to find an encoder, an error of type ErrNoEncoder is returned. The same precedence
79
// rules apply for decoders, with the exception that an error of type ErrNoDecoder will be returned if no decoder is
80
// found.
81
//
82
// # DefaultValueEncoders and DefaultValueDecoders
83
//
84
// The DefaultValueEncoders and DefaultValueDecoders types provide a full set of ValueEncoders and
85
// ValueDecoders for handling a wide range of Go types, including all of the types within the
86
// primitive package. To make registering these codecs easier, a helper method on each type is
87
// provided. For the DefaultValueEncoders type the method is called RegisterDefaultEncoders and for
88
// the DefaultValueDecoders type the method is called RegisterDefaultDecoders, this method also
89
// handles registering type map entries for each BSON type.
90
package bsoncodec
91