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