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// 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 impl
import (
"reflect"
"google.golang.org/protobuf/internal/descopts"
"google.golang.org/protobuf/internal/encoding/messageset"
ptag "google.golang.org/protobuf/internal/encoding/tag"
"google.golang.org/protobuf/internal/filedesc"
"google.golang.org/protobuf/internal/pragma"
pref "google.golang.org/protobuf/reflect/protoreflect"
preg "google.golang.org/protobuf/reflect/protoregistry"
piface "google.golang.org/protobuf/runtime/protoiface"
)
func (xi *ExtensionInfo) initToLegacy() {
xd := xi.desc
var parent piface.MessageV1
messageName := xd.ContainingMessage().FullName()
if mt, _ := preg.GlobalTypes.FindMessageByName(messageName); mt != nil {
// Create a new parent message and unwrap it if possible.
mv := mt.New().Interface()
t := reflect.TypeOf(mv)
if mv, ok := mv.(unwrapper); ok {
t = reflect.TypeOf(mv.protoUnwrap())
}
// Check whether the message implements the legacy v1 Message interface.
mz := reflect.Zero(t).Interface()
if mz, ok := mz.(piface.MessageV1); ok {
parent = mz
}
}
// Determine the v1 extension type, which is unfortunately not the same as
// the v2 ExtensionType.GoType.
extType := xi.goType
switch extType.Kind() {
case reflect.Bool, reflect.Int32, reflect.Int64, reflect.Uint32, reflect.Uint64, reflect.Float32, reflect.Float64, reflect.String:
extType = reflect.PtrTo(extType) // T -> *T for singular scalar fields
}
// Reconstruct the legacy enum full name.
var enumName string
if xd.Kind() == pref.EnumKind {
enumName = legacyEnumName(xd.Enum())
}
// Derive the proto file that the extension was declared within.
var filename string
if fd := xd.ParentFile(); fd != nil {
filename = fd.Path()
}
// For MessageSet extensions, the name used is the parent message.
name := xd.FullName()
if messageset.IsMessageSetExtension(xd) {
name = name.Parent()
}
xi.ExtendedType = parent
xi.ExtensionType = reflect.Zero(extType).Interface()
xi.Field = int32(xd.Number())
xi.Name = string(name)
xi.Tag = ptag.Marshal(xd, enumName)
xi.Filename = filename
}
// initFromLegacy initializes an ExtensionInfo from
// the contents of the deprecated exported fields of the type.
func (xi *ExtensionInfo) initFromLegacy() {
// The v1 API returns "type incomplete" descriptors where only the
// field number is specified. In such a case, use a placeholder.
if xi.ExtendedType == nil || xi.ExtensionType == nil {
xd := placeholderExtension{
name: pref.FullName(xi.Name),
number: pref.FieldNumber(xi.Field),
}
xi.desc = extensionTypeDescriptor{xd, xi}
return
}
// Resolve enum or message dependencies.
var ed pref.EnumDescriptor
var md pref.MessageDescriptor
t := reflect.TypeOf(xi.ExtensionType)
isOptional := t.Kind() == reflect.Ptr && t.Elem().Kind() != reflect.Struct
isRepeated := t.Kind() == reflect.Slice && t.Elem().Kind() != reflect.Uint8
if isOptional || isRepeated {
t = t.Elem()
}
switch v := reflect.Zero(t).Interface().(type) {
case pref.Enum:
ed = v.Descriptor()
case enumV1:
ed = LegacyLoadEnumDesc(t)
case pref.ProtoMessage:
md = v.ProtoReflect().Descriptor()
case messageV1:
md = LegacyLoadMessageDesc(t)
}
// Derive basic field information from the struct tag.
var evs pref.EnumValueDescriptors
if ed != nil {
evs = ed.Values()
}
fd := ptag.Unmarshal(xi.Tag, t, evs).(*filedesc.Field)
// Construct a v2 ExtensionType.
xd := &filedesc.Extension{L2: new(filedesc.ExtensionL2)}
xd.L0.ParentFile = filedesc.SurrogateProto2
xd.L0.FullName = pref.FullName(xi.Name)
xd.L1.Number = pref.FieldNumber(xi.Field)
xd.L1.Cardinality = fd.L1.Cardinality
xd.L1.Kind = fd.L1.Kind
xd.L2.IsPacked = fd.L1.IsPacked
xd.L2.Default = fd.L1.Default
xd.L1.Extendee = Export{}.MessageDescriptorOf(xi.ExtendedType)
xd.L2.Enum = ed
xd.L2.Message = md
// Derive real extension field name for MessageSets.
if messageset.IsMessageSet(xd.L1.Extendee) && md.FullName() == xd.L0.FullName {
xd.L0.FullName = xd.L0.FullName.Append(messageset.ExtensionName)
}
tt := reflect.TypeOf(xi.ExtensionType)
if isOptional {
tt = tt.Elem()
}
xi.goType = tt
xi.desc = extensionTypeDescriptor{xd, xi}
}
type placeholderExtension struct {
name pref.FullName
number pref.FieldNumber
}
func (x placeholderExtension) ParentFile() pref.FileDescriptor { return nil }
func (x placeholderExtension) Parent() pref.Descriptor { return nil }
func (x placeholderExtension) Index() int { return 0 }
func (x placeholderExtension) Syntax() pref.Syntax { return 0 }
func (x placeholderExtension) Name() pref.Name { return x.name.Name() }
func (x placeholderExtension) FullName() pref.FullName { return x.name }
func (x placeholderExtension) IsPlaceholder() bool { return true }
func (x placeholderExtension) Options() pref.ProtoMessage { return descopts.Field }
func (x placeholderExtension) Number() pref.FieldNumber { return x.number }
func (x placeholderExtension) Cardinality() pref.Cardinality { return 0 }
func (x placeholderExtension) Kind() pref.Kind { return 0 }
func (x placeholderExtension) HasJSONName() bool { return false }
func (x placeholderExtension) JSONName() string { return "" }
func (x placeholderExtension) HasPresence() bool { return false }
func (x placeholderExtension) HasOptionalKeyword() bool { return false }
func (x placeholderExtension) IsExtension() bool { return true }
func (x placeholderExtension) IsWeak() bool { return false }
func (x placeholderExtension) IsPacked() bool { return false }
func (x placeholderExtension) IsList() bool { return false }
func (x placeholderExtension) IsMap() bool { return false }
func (x placeholderExtension) MapKey() pref.FieldDescriptor { return nil }
func (x placeholderExtension) MapValue() pref.FieldDescriptor { return nil }
func (x placeholderExtension) HasDefault() bool { return false }
func (x placeholderExtension) Default() pref.Value { return pref.Value{} }
func (x placeholderExtension) DefaultEnumValue() pref.EnumValueDescriptor { return nil }
func (x placeholderExtension) ContainingOneof() pref.OneofDescriptor { return nil }
func (x placeholderExtension) ContainingMessage() pref.MessageDescriptor { return nil }
func (x placeholderExtension) Enum() pref.EnumDescriptor { return nil }
func (x placeholderExtension) Message() pref.MessageDescriptor { return nil }
func (x placeholderExtension) ProtoType(pref.FieldDescriptor) { return }
func (x placeholderExtension) ProtoInternal(pragma.DoNotImplement) { return }
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