mirror of
https://github.com/go-gitea/gitea.git
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385 lines
11 KiB
Go
385 lines
11 KiB
Go
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// Copyright (C) MongoDB, Inc. 2017-present.
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//
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// Licensed under the Apache License, Version 2.0 (the "License"); you may
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// not use this file except in compliance with the License. You may obtain
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// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
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package bsoncodec
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import (
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"errors"
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"reflect"
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"sync"
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"go.mongodb.org/mongo-driver/bson/bsontype"
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)
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// ErrNilType is returned when nil is passed to either LookupEncoder or LookupDecoder.
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var ErrNilType = errors.New("cannot perform a decoder lookup on <nil>")
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// ErrNotPointer is returned when a non-pointer type is provided to LookupDecoder.
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var ErrNotPointer = errors.New("non-pointer provided to LookupDecoder")
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// ErrNoEncoder is returned when there wasn't an encoder available for a type.
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type ErrNoEncoder struct {
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Type reflect.Type
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}
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func (ene ErrNoEncoder) Error() string {
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if ene.Type == nil {
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return "no encoder found for <nil>"
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}
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return "no encoder found for " + ene.Type.String()
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}
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// ErrNoDecoder is returned when there wasn't a decoder available for a type.
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type ErrNoDecoder struct {
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Type reflect.Type
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}
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func (end ErrNoDecoder) Error() string {
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return "no decoder found for " + end.Type.String()
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}
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// ErrNoTypeMapEntry is returned when there wasn't a type available for the provided BSON type.
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type ErrNoTypeMapEntry struct {
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Type bsontype.Type
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}
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func (entme ErrNoTypeMapEntry) Error() string {
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return "no type map entry found for " + entme.Type.String()
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}
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// ErrNotInterface is returned when the provided type is not an interface.
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var ErrNotInterface = errors.New("The provided type is not an interface")
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var defaultRegistry *Registry
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func init() {
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defaultRegistry = buildDefaultRegistry()
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}
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// A RegistryBuilder is used to build a Registry. This type is not goroutine
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// safe.
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type RegistryBuilder struct {
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typeEncoders map[reflect.Type]ValueEncoder
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interfaceEncoders []interfaceValueEncoder
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kindEncoders map[reflect.Kind]ValueEncoder
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typeDecoders map[reflect.Type]ValueDecoder
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interfaceDecoders []interfaceValueDecoder
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kindDecoders map[reflect.Kind]ValueDecoder
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typeMap map[bsontype.Type]reflect.Type
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}
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// A Registry is used to store and retrieve codecs for types and interfaces. This type is the main
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// typed passed around and Encoders and Decoders are constructed from it.
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type Registry struct {
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typeEncoders map[reflect.Type]ValueEncoder
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typeDecoders map[reflect.Type]ValueDecoder
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interfaceEncoders []interfaceValueEncoder
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interfaceDecoders []interfaceValueDecoder
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kindEncoders map[reflect.Kind]ValueEncoder
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kindDecoders map[reflect.Kind]ValueDecoder
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typeMap map[bsontype.Type]reflect.Type
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mu sync.RWMutex
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}
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// NewRegistryBuilder creates a new empty RegistryBuilder.
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func NewRegistryBuilder() *RegistryBuilder {
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return &RegistryBuilder{
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typeEncoders: make(map[reflect.Type]ValueEncoder),
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typeDecoders: make(map[reflect.Type]ValueDecoder),
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interfaceEncoders: make([]interfaceValueEncoder, 0),
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interfaceDecoders: make([]interfaceValueDecoder, 0),
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kindEncoders: make(map[reflect.Kind]ValueEncoder),
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kindDecoders: make(map[reflect.Kind]ValueDecoder),
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typeMap: make(map[bsontype.Type]reflect.Type),
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}
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}
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func buildDefaultRegistry() *Registry {
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rb := NewRegistryBuilder()
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defaultValueEncoders.RegisterDefaultEncoders(rb)
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defaultValueDecoders.RegisterDefaultDecoders(rb)
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return rb.Build()
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}
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// RegisterCodec will register the provided ValueCodec for the provided type.
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func (rb *RegistryBuilder) RegisterCodec(t reflect.Type, codec ValueCodec) *RegistryBuilder {
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rb.RegisterEncoder(t, codec)
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rb.RegisterDecoder(t, codec)
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return rb
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}
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// RegisterEncoder will register the provided ValueEncoder to the provided type.
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//
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// The type registered will be used directly, so an encoder can be registered for a type and a
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// different encoder can be registered for a pointer to that type.
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func (rb *RegistryBuilder) RegisterEncoder(t reflect.Type, enc ValueEncoder) *RegistryBuilder {
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if t == tEmpty {
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rb.typeEncoders[t] = enc
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return rb
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}
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switch t.Kind() {
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case reflect.Interface:
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for idx, ir := range rb.interfaceEncoders {
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if ir.i == t {
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rb.interfaceEncoders[idx].ve = enc
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return rb
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}
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}
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rb.interfaceEncoders = append(rb.interfaceEncoders, interfaceValueEncoder{i: t, ve: enc})
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default:
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rb.typeEncoders[t] = enc
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}
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return rb
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}
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// RegisterDecoder will register the provided ValueDecoder to the provided type.
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//
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// The type registered will be used directly, so a decoder can be registered for a type and a
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// different decoder can be registered for a pointer to that type.
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func (rb *RegistryBuilder) RegisterDecoder(t reflect.Type, dec ValueDecoder) *RegistryBuilder {
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if t == nil {
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rb.typeDecoders[nil] = dec
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return rb
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}
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if t == tEmpty {
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rb.typeDecoders[t] = dec
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return rb
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}
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switch t.Kind() {
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case reflect.Interface:
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for idx, ir := range rb.interfaceDecoders {
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if ir.i == t {
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rb.interfaceDecoders[idx].vd = dec
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return rb
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}
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}
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rb.interfaceDecoders = append(rb.interfaceDecoders, interfaceValueDecoder{i: t, vd: dec})
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default:
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rb.typeDecoders[t] = dec
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}
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return rb
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}
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// RegisterDefaultEncoder will registr the provided ValueEncoder to the provided
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// kind.
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func (rb *RegistryBuilder) RegisterDefaultEncoder(kind reflect.Kind, enc ValueEncoder) *RegistryBuilder {
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rb.kindEncoders[kind] = enc
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return rb
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}
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// RegisterDefaultDecoder will register the provided ValueDecoder to the
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// provided kind.
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func (rb *RegistryBuilder) RegisterDefaultDecoder(kind reflect.Kind, dec ValueDecoder) *RegistryBuilder {
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rb.kindDecoders[kind] = dec
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return rb
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}
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// RegisterTypeMapEntry will register the provided type to the BSON type. The primary usage for this
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// mapping is decoding situations where an empty interface is used and a default type needs to be
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// created and decoded into.
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//
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// NOTE: It is unlikely that registering a type for BSON Embedded Document is actually desired. By
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// registering a type map entry for BSON Embedded Document the type registered will be used in any
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// case where a BSON Embedded Document will be decoded into an empty interface. For example, if you
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// register primitive.M, the EmptyInterface decoder will always use primitive.M, even if an ancestor
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// was a primitive.D.
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func (rb *RegistryBuilder) RegisterTypeMapEntry(bt bsontype.Type, rt reflect.Type) *RegistryBuilder {
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rb.typeMap[bt] = rt
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return rb
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}
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// Build creates a Registry from the current state of this RegistryBuilder.
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func (rb *RegistryBuilder) Build() *Registry {
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registry := new(Registry)
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registry.typeEncoders = make(map[reflect.Type]ValueEncoder)
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for t, enc := range rb.typeEncoders {
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registry.typeEncoders[t] = enc
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}
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registry.typeDecoders = make(map[reflect.Type]ValueDecoder)
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for t, dec := range rb.typeDecoders {
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registry.typeDecoders[t] = dec
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}
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registry.interfaceEncoders = make([]interfaceValueEncoder, len(rb.interfaceEncoders))
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copy(registry.interfaceEncoders, rb.interfaceEncoders)
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registry.interfaceDecoders = make([]interfaceValueDecoder, len(rb.interfaceDecoders))
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copy(registry.interfaceDecoders, rb.interfaceDecoders)
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registry.kindEncoders = make(map[reflect.Kind]ValueEncoder)
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for kind, enc := range rb.kindEncoders {
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registry.kindEncoders[kind] = enc
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}
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registry.kindDecoders = make(map[reflect.Kind]ValueDecoder)
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for kind, dec := range rb.kindDecoders {
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registry.kindDecoders[kind] = dec
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}
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registry.typeMap = make(map[bsontype.Type]reflect.Type)
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for bt, rt := range rb.typeMap {
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registry.typeMap[bt] = rt
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}
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return registry
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}
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// LookupEncoder will inspect the registry for an encoder that satisfies the
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// type provided. An encoder registered for a specific type will take
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// precedence over an encoder registered for an interface the type satisfies,
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// which takes precedence over an encoder for the reflect.Kind of the value. If
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// no encoder can be found, an error is returned.
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func (r *Registry) LookupEncoder(t reflect.Type) (ValueEncoder, error) {
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encodererr := ErrNoEncoder{Type: t}
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r.mu.RLock()
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enc, found := r.lookupTypeEncoder(t)
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r.mu.RUnlock()
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if found {
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if enc == nil {
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return nil, ErrNoEncoder{Type: t}
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}
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return enc, nil
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}
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enc, found = r.lookupInterfaceEncoder(t)
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if found {
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r.mu.Lock()
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r.typeEncoders[t] = enc
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r.mu.Unlock()
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return enc, nil
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}
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if t == nil {
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r.mu.Lock()
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r.typeEncoders[t] = nil
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r.mu.Unlock()
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return nil, encodererr
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}
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enc, found = r.kindEncoders[t.Kind()]
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if !found {
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r.mu.Lock()
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r.typeEncoders[t] = nil
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r.mu.Unlock()
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return nil, encodererr
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}
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r.mu.Lock()
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r.typeEncoders[t] = enc
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r.mu.Unlock()
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return enc, nil
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}
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func (r *Registry) lookupTypeEncoder(t reflect.Type) (ValueEncoder, bool) {
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enc, found := r.typeEncoders[t]
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return enc, found
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}
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func (r *Registry) lookupInterfaceEncoder(t reflect.Type) (ValueEncoder, bool) {
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if t == nil {
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return nil, false
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}
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for _, ienc := range r.interfaceEncoders {
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if !t.Implements(ienc.i) {
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continue
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}
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return ienc.ve, true
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}
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return nil, false
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}
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// LookupDecoder will inspect the registry for a decoder that satisfies the
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// type provided. A decoder registered for a specific type will take
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// precedence over a decoder registered for an interface the type satisfies,
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// which takes precedence over a decoder for the reflect.Kind of the value. If
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// no decoder can be found, an error is returned.
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func (r *Registry) LookupDecoder(t reflect.Type) (ValueDecoder, error) {
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if t == nil {
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return nil, ErrNilType
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}
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decodererr := ErrNoDecoder{Type: t}
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r.mu.RLock()
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dec, found := r.lookupTypeDecoder(t)
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r.mu.RUnlock()
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if found {
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if dec == nil {
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return nil, ErrNoDecoder{Type: t}
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}
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return dec, nil
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}
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dec, found = r.lookupInterfaceDecoder(t)
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if found {
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r.mu.Lock()
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r.typeDecoders[t] = dec
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r.mu.Unlock()
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return dec, nil
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}
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dec, found = r.kindDecoders[t.Kind()]
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if !found {
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r.mu.Lock()
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r.typeDecoders[t] = nil
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r.mu.Unlock()
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return nil, decodererr
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}
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r.mu.Lock()
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r.typeDecoders[t] = dec
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r.mu.Unlock()
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return dec, nil
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}
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func (r *Registry) lookupTypeDecoder(t reflect.Type) (ValueDecoder, bool) {
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dec, found := r.typeDecoders[t]
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return dec, found
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}
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func (r *Registry) lookupInterfaceDecoder(t reflect.Type) (ValueDecoder, bool) {
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for _, idec := range r.interfaceDecoders {
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if !t.Implements(idec.i) && !reflect.PtrTo(t).Implements(idec.i) {
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continue
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}
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return idec.vd, true
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}
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return nil, false
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}
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// LookupTypeMapEntry inspects the registry's type map for a Go type for the corresponding BSON
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// type. If no type is found, ErrNoTypeMapEntry is returned.
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func (r *Registry) LookupTypeMapEntry(bt bsontype.Type) (reflect.Type, error) {
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t, ok := r.typeMap[bt]
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if !ok || t == nil {
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return nil, ErrNoTypeMapEntry{Type: bt}
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}
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return t, nil
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}
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type interfaceValueEncoder struct {
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i reflect.Type
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ve ValueEncoder
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}
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type interfaceValueDecoder struct {
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i reflect.Type
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vd ValueDecoder
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}
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