277 lines
8.2 KiB
Go
277 lines
8.2 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package impl
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import (
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"fmt"
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"reflect"
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"strconv"
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"strings"
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"sync"
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"sync/atomic"
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"google.golang.org/protobuf/internal/genid"
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"google.golang.org/protobuf/reflect/protoreflect"
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pref "google.golang.org/protobuf/reflect/protoreflect"
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preg "google.golang.org/protobuf/reflect/protoregistry"
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)
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// MessageInfo provides protobuf related functionality for a given Go type
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// that represents a message. A given instance of MessageInfo is tied to
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// exactly one Go type, which must be a pointer to a struct type.
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//
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// The exported fields must be populated before any methods are called
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// and cannot be mutated after set.
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type MessageInfo struct {
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// GoReflectType is the underlying message Go type and must be populated.
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GoReflectType reflect.Type // pointer to struct
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// Desc is the underlying message descriptor type and must be populated.
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Desc pref.MessageDescriptor
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// Exporter must be provided in a purego environment in order to provide
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// access to unexported fields.
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Exporter exporter
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// OneofWrappers is list of pointers to oneof wrapper struct types.
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OneofWrappers []interface{}
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initMu sync.Mutex // protects all unexported fields
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initDone uint32
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reflectMessageInfo // for reflection implementation
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coderMessageInfo // for fast-path method implementations
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}
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// exporter is a function that returns a reference to the ith field of v,
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// where v is a pointer to a struct. It returns nil if it does not support
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// exporting the requested field (e.g., already exported).
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type exporter func(v interface{}, i int) interface{}
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// getMessageInfo returns the MessageInfo for any message type that
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// is generated by our implementation of protoc-gen-go (for v2 and on).
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// If it is unable to obtain a MessageInfo, it returns nil.
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func getMessageInfo(mt reflect.Type) *MessageInfo {
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m, ok := reflect.Zero(mt).Interface().(pref.ProtoMessage)
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if !ok {
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return nil
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}
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mr, ok := m.ProtoReflect().(interface{ ProtoMessageInfo() *MessageInfo })
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if !ok {
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return nil
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}
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return mr.ProtoMessageInfo()
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}
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func (mi *MessageInfo) init() {
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// This function is called in the hot path. Inline the sync.Once logic,
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// since allocating a closure for Once.Do is expensive.
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// Keep init small to ensure that it can be inlined.
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if atomic.LoadUint32(&mi.initDone) == 0 {
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mi.initOnce()
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}
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}
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func (mi *MessageInfo) initOnce() {
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mi.initMu.Lock()
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defer mi.initMu.Unlock()
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if mi.initDone == 1 {
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return
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}
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t := mi.GoReflectType
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if t.Kind() != reflect.Ptr && t.Elem().Kind() != reflect.Struct {
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panic(fmt.Sprintf("got %v, want *struct kind", t))
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}
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t = t.Elem()
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si := mi.makeStructInfo(t)
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mi.makeReflectFuncs(t, si)
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mi.makeCoderMethods(t, si)
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atomic.StoreUint32(&mi.initDone, 1)
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}
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// getPointer returns the pointer for a message, which should be of
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// the type of the MessageInfo. If the message is of a different type,
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// it returns ok==false.
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func (mi *MessageInfo) getPointer(m pref.Message) (p pointer, ok bool) {
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switch m := m.(type) {
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case *messageState:
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return m.pointer(), m.messageInfo() == mi
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case *messageReflectWrapper:
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return m.pointer(), m.messageInfo() == mi
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}
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return pointer{}, false
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}
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type (
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SizeCache = int32
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WeakFields = map[int32]protoreflect.ProtoMessage
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UnknownFields = unknownFieldsA // TODO: switch to unknownFieldsB
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unknownFieldsA = []byte
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unknownFieldsB = *[]byte
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ExtensionFields = map[int32]ExtensionField
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)
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var (
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sizecacheType = reflect.TypeOf(SizeCache(0))
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weakFieldsType = reflect.TypeOf(WeakFields(nil))
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unknownFieldsAType = reflect.TypeOf(unknownFieldsA(nil))
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unknownFieldsBType = reflect.TypeOf(unknownFieldsB(nil))
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extensionFieldsType = reflect.TypeOf(ExtensionFields(nil))
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)
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type structInfo struct {
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sizecacheOffset offset
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sizecacheType reflect.Type
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weakOffset offset
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weakType reflect.Type
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unknownOffset offset
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unknownType reflect.Type
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extensionOffset offset
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extensionType reflect.Type
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fieldsByNumber map[pref.FieldNumber]reflect.StructField
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oneofsByName map[pref.Name]reflect.StructField
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oneofWrappersByType map[reflect.Type]pref.FieldNumber
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oneofWrappersByNumber map[pref.FieldNumber]reflect.Type
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}
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func (mi *MessageInfo) makeStructInfo(t reflect.Type) structInfo {
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si := structInfo{
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sizecacheOffset: invalidOffset,
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weakOffset: invalidOffset,
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unknownOffset: invalidOffset,
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extensionOffset: invalidOffset,
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fieldsByNumber: map[pref.FieldNumber]reflect.StructField{},
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oneofsByName: map[pref.Name]reflect.StructField{},
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oneofWrappersByType: map[reflect.Type]pref.FieldNumber{},
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oneofWrappersByNumber: map[pref.FieldNumber]reflect.Type{},
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}
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fieldLoop:
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for i := 0; i < t.NumField(); i++ {
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switch f := t.Field(i); f.Name {
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case genid.SizeCache_goname, genid.SizeCacheA_goname:
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if f.Type == sizecacheType {
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si.sizecacheOffset = offsetOf(f, mi.Exporter)
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si.sizecacheType = f.Type
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}
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case genid.WeakFields_goname, genid.WeakFieldsA_goname:
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if f.Type == weakFieldsType {
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si.weakOffset = offsetOf(f, mi.Exporter)
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si.weakType = f.Type
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}
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case genid.UnknownFields_goname, genid.UnknownFieldsA_goname:
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if f.Type == unknownFieldsAType || f.Type == unknownFieldsBType {
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si.unknownOffset = offsetOf(f, mi.Exporter)
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si.unknownType = f.Type
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}
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case genid.ExtensionFields_goname, genid.ExtensionFieldsA_goname, genid.ExtensionFieldsB_goname:
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if f.Type == extensionFieldsType {
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si.extensionOffset = offsetOf(f, mi.Exporter)
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si.extensionType = f.Type
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}
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default:
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for _, s := range strings.Split(f.Tag.Get("protobuf"), ",") {
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if len(s) > 0 && strings.Trim(s, "0123456789") == "" {
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n, _ := strconv.ParseUint(s, 10, 64)
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si.fieldsByNumber[pref.FieldNumber(n)] = f
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continue fieldLoop
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}
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}
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if s := f.Tag.Get("protobuf_oneof"); len(s) > 0 {
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si.oneofsByName[pref.Name(s)] = f
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continue fieldLoop
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}
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}
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}
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// Derive a mapping of oneof wrappers to fields.
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oneofWrappers := mi.OneofWrappers
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for _, method := range []string{"XXX_OneofFuncs", "XXX_OneofWrappers"} {
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if fn, ok := reflect.PtrTo(t).MethodByName(method); ok {
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for _, v := range fn.Func.Call([]reflect.Value{reflect.Zero(fn.Type.In(0))}) {
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if vs, ok := v.Interface().([]interface{}); ok {
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oneofWrappers = vs
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}
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}
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}
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}
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for _, v := range oneofWrappers {
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tf := reflect.TypeOf(v).Elem()
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f := tf.Field(0)
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for _, s := range strings.Split(f.Tag.Get("protobuf"), ",") {
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if len(s) > 0 && strings.Trim(s, "0123456789") == "" {
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n, _ := strconv.ParseUint(s, 10, 64)
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si.oneofWrappersByType[tf] = pref.FieldNumber(n)
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si.oneofWrappersByNumber[pref.FieldNumber(n)] = tf
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break
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}
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}
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}
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return si
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}
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func (mi *MessageInfo) New() protoreflect.Message {
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return mi.MessageOf(reflect.New(mi.GoReflectType.Elem()).Interface())
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}
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func (mi *MessageInfo) Zero() protoreflect.Message {
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return mi.MessageOf(reflect.Zero(mi.GoReflectType).Interface())
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}
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func (mi *MessageInfo) Descriptor() protoreflect.MessageDescriptor {
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return mi.Desc
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}
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func (mi *MessageInfo) Enum(i int) protoreflect.EnumType {
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mi.init()
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fd := mi.Desc.Fields().Get(i)
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return Export{}.EnumTypeOf(mi.fieldTypes[fd.Number()])
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}
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func (mi *MessageInfo) Message(i int) protoreflect.MessageType {
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mi.init()
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fd := mi.Desc.Fields().Get(i)
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switch {
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case fd.IsWeak():
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mt, _ := preg.GlobalTypes.FindMessageByName(fd.Message().FullName())
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return mt
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case fd.IsMap():
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return mapEntryType{fd.Message(), mi.fieldTypes[fd.Number()]}
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default:
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return Export{}.MessageTypeOf(mi.fieldTypes[fd.Number()])
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}
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}
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type mapEntryType struct {
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desc protoreflect.MessageDescriptor
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valType interface{} // zero value of enum or message type
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}
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func (mt mapEntryType) New() protoreflect.Message {
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return nil
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}
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func (mt mapEntryType) Zero() protoreflect.Message {
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return nil
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}
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func (mt mapEntryType) Descriptor() protoreflect.MessageDescriptor {
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return mt.desc
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}
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func (mt mapEntryType) Enum(i int) protoreflect.EnumType {
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fd := mt.desc.Fields().Get(i)
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if fd.Enum() == nil {
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return nil
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}
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return Export{}.EnumTypeOf(mt.valType)
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}
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func (mt mapEntryType) Message(i int) protoreflect.MessageType {
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fd := mt.desc.Fields().Get(i)
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if fd.Message() == nil {
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return nil
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}
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return Export{}.MessageTypeOf(mt.valType)
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}
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