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Diffstat (limited to 'vendor/go.mongodb.org/mongo-driver/bson/bsoncodec/doc.go')
| -rw-r--r-- | vendor/go.mongodb.org/mongo-driver/bson/bsoncodec/doc.go | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/vendor/go.mongodb.org/mongo-driver/bson/bsoncodec/doc.go b/vendor/go.mongodb.org/mongo-driver/bson/bsoncodec/doc.go new file mode 100644 index 000000000..5f903ebea --- /dev/null +++ b/vendor/go.mongodb.org/mongo-driver/bson/bsoncodec/doc.go @@ -0,0 +1,90 @@ +// Copyright (C) MongoDB, Inc. 2022-present. +// +// Licensed under the Apache License, Version 2.0 (the "License"); you may +// not use this file except in compliance with the License. You may obtain +// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 + +// Package bsoncodec provides a system for encoding values to BSON representations and decoding +// values from BSON representations. This package considers both binary BSON and ExtendedJSON as +// BSON representations. The types in this package enable a flexible system for handling this +// encoding and decoding. +// +// The codec system is composed of two parts: +// +// 1) ValueEncoders and ValueDecoders that handle encoding and decoding Go values to and from BSON +// representations. +// +// 2) A Registry that holds these ValueEncoders and ValueDecoders and provides methods for +// retrieving them. +// +// # ValueEncoders and ValueDecoders +// +// The ValueEncoder interface is implemented by types that can encode a provided Go type to BSON. +// The value to encode is provided as a reflect.Value and a bsonrw.ValueWriter is used within the +// EncodeValue method to actually create the BSON representation. For convenience, ValueEncoderFunc +// is provided to allow use of a function with the correct signature as a ValueEncoder. An +// EncodeContext instance is provided to allow implementations to lookup further ValueEncoders and +// to provide configuration information. +// +// The ValueDecoder interface is the inverse of the ValueEncoder. Implementations should ensure that +// the value they receive is settable. Similar to ValueEncoderFunc, ValueDecoderFunc is provided to +// allow the use of a function with the correct signature as a ValueDecoder. A DecodeContext +// instance is provided and serves similar functionality to the EncodeContext. +// +// # Registry and RegistryBuilder +// +// A Registry is an immutable store for ValueEncoders, ValueDecoders, and a type map. See the Registry type +// documentation for examples of registering various custom encoders and decoders. A Registry can be constructed using a +// RegistryBuilder, which handles three main types of codecs: +// +// 1. Type encoders/decoders - These can be registered using the RegisterTypeEncoder and RegisterTypeDecoder methods. +// The registered codec will be invoked when encoding/decoding a value whose type matches the registered type exactly. +// If the registered type is an interface, the codec will be invoked when encoding or decoding values whose type is the +// interface, but not for values with concrete types that implement the interface. +// +// 2. Hook encoders/decoders - These can be registered using the RegisterHookEncoder and RegisterHookDecoder methods. +// These methods only accept interface types and the registered codecs will be invoked when encoding or decoding values +// whose types implement the interface. An example of a hook defined by the driver is bson.Marshaler. The driver will +// call the MarshalBSON method for any value whose type implements bson.Marshaler, regardless of the value's concrete +// type. +// +// 3. Type map entries - This can be used to associate a BSON type with a Go type. These type associations are used when +// decoding into a bson.D/bson.M or a struct field of type interface{}. For example, by default, BSON int32 and int64 +// values decode as Go int32 and int64 instances, respectively, when decoding into a bson.D. The following code would +// change the behavior so these values decode as Go int instances instead: +// +// intType := reflect.TypeOf(int(0)) +// registryBuilder.RegisterTypeMapEntry(bsontype.Int32, intType).RegisterTypeMapEntry(bsontype.Int64, intType) +// +// 4. Kind encoder/decoders - These can be registered using the RegisterDefaultEncoder and RegisterDefaultDecoder +// methods. The registered codec will be invoked when encoding or decoding values whose reflect.Kind matches the +// registered reflect.Kind as long as the value's type doesn't match a registered type or hook encoder/decoder first. +// These methods should be used to change the behavior for all values for a specific kind. +// +// # Registry Lookup Procedure +// +// When looking up an encoder in a Registry, the precedence rules are as follows: +// +// 1. A type encoder registered for the exact type of the value. +// +// 2. A hook encoder registered for an interface that is implemented by the value or by a pointer to the value. If the +// value matches multiple hooks (e.g. the type implements bsoncodec.Marshaler and bsoncodec.ValueMarshaler), the first +// one registered will be selected. Note that registries constructed using bson.NewRegistryBuilder have driver-defined +// hooks registered for the bsoncodec.Marshaler, bsoncodec.ValueMarshaler, and bsoncodec.Proxy interfaces, so those +// will take precedence over any new hooks. +// +// 3. A kind encoder registered for the value's kind. +// +// If all of these lookups fail to find an encoder, an error of type ErrNoEncoder is returned. The same precedence +// rules apply for decoders, with the exception that an error of type ErrNoDecoder will be returned if no decoder is +// found. +// +// # DefaultValueEncoders and DefaultValueDecoders +// +// The DefaultValueEncoders and DefaultValueDecoders types provide a full set of ValueEncoders and +// ValueDecoders for handling a wide range of Go types, including all of the types within the +// primitive package. To make registering these codecs easier, a helper method on each type is +// provided. For the DefaultValueEncoders type the method is called RegisterDefaultEncoders and for +// the DefaultValueDecoders type the method is called RegisterDefaultDecoders, this method also +// handles registering type map entries for each BSON type. +package bsoncodec |