blob: eb8d5708537f29f8f01dce4132a36eeeadbb997d [file] [log] [blame]
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package value provides functionality for wrapping Go values to implement
// protoreflect values.
package value
import (
"fmt"
"reflect"
pref "google.golang.org/protobuf/reflect/protoreflect"
)
// Unwrapper unwraps the value to the underlying value.
// This is implemented by List and Map.
type Unwrapper interface {
ProtoUnwrap() interface{}
}
var (
boolType = reflect.TypeOf(bool(false))
int32Type = reflect.TypeOf(int32(0))
int64Type = reflect.TypeOf(int64(0))
uint32Type = reflect.TypeOf(uint32(0))
uint64Type = reflect.TypeOf(uint64(0))
float32Type = reflect.TypeOf(float32(0))
float64Type = reflect.TypeOf(float64(0))
stringType = reflect.TypeOf(string(""))
bytesType = reflect.TypeOf([]byte(nil))
enumIfaceV2 = reflect.TypeOf((*pref.Enum)(nil)).Elem()
messageIfaceV2 = reflect.TypeOf((*pref.ProtoMessage)(nil)).Elem()
byteType = reflect.TypeOf(byte(0))
)
// NewConverter matches a Go type with a protobuf kind and returns a Converter
// that converts between the two. Enums must be a named int32 kind that
// implements protoreflect.Enum, and messages must be pointer to a named
// struct type that implements protoreflect.ProtoMessage.
//
// This matcher deliberately supports a wider range of Go types than what
// protoc-gen-go historically generated to be able to automatically wrap some
// v1 messages generated by other forks of protoc-gen-go.
func NewConverter(t reflect.Type, k pref.Kind) Converter {
switch k {
case pref.BoolKind:
if t.Kind() == reflect.Bool {
return newScalarConverter(t, boolType)
}
case pref.Int32Kind, pref.Sint32Kind, pref.Sfixed32Kind:
if t.Kind() == reflect.Int32 {
return newScalarConverter(t, int32Type)
}
case pref.Int64Kind, pref.Sint64Kind, pref.Sfixed64Kind:
if t.Kind() == reflect.Int64 {
return newScalarConverter(t, int64Type)
}
case pref.Uint32Kind, pref.Fixed32Kind:
if t.Kind() == reflect.Uint32 {
return newScalarConverter(t, uint32Type)
}
case pref.Uint64Kind, pref.Fixed64Kind:
if t.Kind() == reflect.Uint64 {
return newScalarConverter(t, uint64Type)
}
case pref.FloatKind:
if t.Kind() == reflect.Float32 {
return newScalarConverter(t, float32Type)
}
case pref.DoubleKind:
if t.Kind() == reflect.Float64 {
return newScalarConverter(t, float64Type)
}
case pref.StringKind:
if t.Kind() == reflect.String || (t.Kind() == reflect.Slice && t.Elem() == byteType) {
return newScalarConverter(t, stringType)
}
case pref.BytesKind:
if t.Kind() == reflect.String || (t.Kind() == reflect.Slice && t.Elem() == byteType) {
return newScalarConverter(t, bytesType)
}
case pref.EnumKind:
// Handle enums, which must be a named int32 type.
if t.Implements(enumIfaceV2) && t.Kind() == reflect.Int32 {
return Converter{
PBValueOf: func(v reflect.Value) pref.Value {
if v.Type() != t {
panic(fmt.Sprintf("invalid type: got %v, want %v", v.Type(), t))
}
return pref.ValueOf(pref.EnumNumber(v.Int()))
},
GoValueOf: func(v pref.Value) reflect.Value {
return reflect.ValueOf(v.Enum()).Convert(t)
},
NewEnum: func(n pref.EnumNumber) pref.Enum {
return reflect.ValueOf(n).Convert(t).Interface().(pref.Enum)
},
}
}
case pref.MessageKind, pref.GroupKind:
// Handle v2 messages, which must satisfy the proto.Message interface.
if t.Implements(messageIfaceV2) && t.Kind() == reflect.Ptr && t.Elem().Kind() == reflect.Struct {
return Converter{
PBValueOf: func(v reflect.Value) pref.Value {
if v.Type() != t {
panic(fmt.Sprintf("invalid type: got %v, want %v", v.Type(), t))
}
return pref.ValueOf(v.Interface().(pref.ProtoMessage).ProtoReflect())
},
GoValueOf: func(v pref.Value) reflect.Value {
rv := reflect.ValueOf(v.Message().Interface())
if rv.Type() != t {
panic(fmt.Sprintf("invalid type: got %v, want %v", rv.Type(), t))
}
return rv
},
NewMessage: func() pref.Message {
return reflect.New(t.Elem()).Interface().(pref.ProtoMessage).ProtoReflect()
},
}
}
}
panic(fmt.Sprintf("invalid Go type %v for protobuf kind %v", t, k))
}
func newScalarConverter(goType, pbType reflect.Type) Converter {
return Converter{
PBValueOf: func(v reflect.Value) pref.Value {
if v.Type() != goType {
panic(fmt.Sprintf("invalid type: got %v, want %v", v.Type(), goType))
}
if goType.Kind() == reflect.String && pbType.Kind() == reflect.Slice && v.Len() == 0 {
return pref.ValueOf([]byte(nil)) // ensure empty string is []byte(nil)
}
return pref.ValueOf(v.Convert(pbType).Interface())
},
GoValueOf: func(v pref.Value) reflect.Value {
rv := reflect.ValueOf(v.Interface())
if rv.Type() != pbType {
panic(fmt.Sprintf("invalid type: got %v, want %v", rv.Type(), pbType))
}
if pbType.Kind() == reflect.String && goType.Kind() == reflect.Slice && rv.Len() == 0 {
return reflect.Zero(goType) // ensure empty string is []byte(nil)
}
return rv.Convert(goType)
},
}
}
// Converter provides functions for converting to/from Go reflect.Value types
// and protobuf protoreflect.Value types.
type Converter struct {
PBValueOf func(reflect.Value) pref.Value
GoValueOf func(pref.Value) reflect.Value
NewEnum func(pref.EnumNumber) pref.Enum
NewMessage func() pref.Message
}