466 lines
13 KiB
Go
466 lines
13 KiB
Go
// Copyright 2019 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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"google.golang.org/protobuf/internal/detrand"
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"google.golang.org/protobuf/internal/pragma"
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pref "google.golang.org/protobuf/reflect/protoreflect"
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)
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type reflectMessageInfo struct {
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fields map[pref.FieldNumber]*fieldInfo
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oneofs map[pref.Name]*oneofInfo
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// fieldTypes contains the zero value of an enum or message field.
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// For lists, it contains the element type.
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// For maps, it contains the entry value type.
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fieldTypes map[pref.FieldNumber]interface{}
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// denseFields is a subset of fields where:
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// 0 < fieldDesc.Number() < len(denseFields)
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// It provides faster access to the fieldInfo, but may be incomplete.
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denseFields []*fieldInfo
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// rangeInfos is a list of all fields (not belonging to a oneof) and oneofs.
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rangeInfos []interface{} // either *fieldInfo or *oneofInfo
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getUnknown func(pointer) pref.RawFields
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setUnknown func(pointer, pref.RawFields)
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extensionMap func(pointer) *extensionMap
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nilMessage atomicNilMessage
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}
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// makeReflectFuncs generates the set of functions to support reflection.
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func (mi *MessageInfo) makeReflectFuncs(t reflect.Type, si structInfo) {
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mi.makeKnownFieldsFunc(si)
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mi.makeUnknownFieldsFunc(t, si)
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mi.makeExtensionFieldsFunc(t, si)
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mi.makeFieldTypes(si)
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}
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// makeKnownFieldsFunc generates functions for operations that can be performed
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// on each protobuf message field. It takes in a reflect.Type representing the
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// Go struct and matches message fields with struct fields.
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//
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// This code assumes that the struct is well-formed and panics if there are
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// any discrepancies.
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func (mi *MessageInfo) makeKnownFieldsFunc(si structInfo) {
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mi.fields = map[pref.FieldNumber]*fieldInfo{}
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md := mi.Desc
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fds := md.Fields()
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for i := 0; i < fds.Len(); i++ {
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fd := fds.Get(i)
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fs := si.fieldsByNumber[fd.Number()]
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isOneof := fd.ContainingOneof() != nil && !fd.ContainingOneof().IsSynthetic()
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if isOneof {
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fs = si.oneofsByName[fd.ContainingOneof().Name()]
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}
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var fi fieldInfo
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switch {
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case fs.Type == nil:
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fi = fieldInfoForMissing(fd) // never occurs for officially generated message types
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case isOneof:
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fi = fieldInfoForOneof(fd, fs, mi.Exporter, si.oneofWrappersByNumber[fd.Number()])
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case fd.IsMap():
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fi = fieldInfoForMap(fd, fs, mi.Exporter)
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case fd.IsList():
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fi = fieldInfoForList(fd, fs, mi.Exporter)
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case fd.IsWeak():
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fi = fieldInfoForWeakMessage(fd, si.weakOffset)
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case fd.Message() != nil:
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fi = fieldInfoForMessage(fd, fs, mi.Exporter)
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default:
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fi = fieldInfoForScalar(fd, fs, mi.Exporter)
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}
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mi.fields[fd.Number()] = &fi
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}
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mi.oneofs = map[pref.Name]*oneofInfo{}
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for i := 0; i < md.Oneofs().Len(); i++ {
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od := md.Oneofs().Get(i)
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mi.oneofs[od.Name()] = makeOneofInfo(od, si, mi.Exporter)
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}
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mi.denseFields = make([]*fieldInfo, fds.Len()*2)
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for i := 0; i < fds.Len(); i++ {
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if fd := fds.Get(i); int(fd.Number()) < len(mi.denseFields) {
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mi.denseFields[fd.Number()] = mi.fields[fd.Number()]
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}
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}
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for i := 0; i < fds.Len(); {
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fd := fds.Get(i)
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if od := fd.ContainingOneof(); od != nil && !od.IsSynthetic() {
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mi.rangeInfos = append(mi.rangeInfos, mi.oneofs[od.Name()])
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i += od.Fields().Len()
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} else {
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mi.rangeInfos = append(mi.rangeInfos, mi.fields[fd.Number()])
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i++
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}
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}
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// Introduce instability to iteration order, but keep it deterministic.
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if len(mi.rangeInfos) > 1 && detrand.Bool() {
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i := detrand.Intn(len(mi.rangeInfos) - 1)
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mi.rangeInfos[i], mi.rangeInfos[i+1] = mi.rangeInfos[i+1], mi.rangeInfos[i]
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}
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}
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func (mi *MessageInfo) makeUnknownFieldsFunc(t reflect.Type, si structInfo) {
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switch {
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case si.unknownOffset.IsValid() && si.unknownType == unknownFieldsAType:
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// Handle as []byte.
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mi.getUnknown = func(p pointer) pref.RawFields {
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if p.IsNil() {
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return nil
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}
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return *p.Apply(mi.unknownOffset).Bytes()
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}
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mi.setUnknown = func(p pointer, b pref.RawFields) {
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if p.IsNil() {
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panic("invalid SetUnknown on nil Message")
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}
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*p.Apply(mi.unknownOffset).Bytes() = b
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}
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case si.unknownOffset.IsValid() && si.unknownType == unknownFieldsBType:
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// Handle as *[]byte.
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mi.getUnknown = func(p pointer) pref.RawFields {
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if p.IsNil() {
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return nil
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}
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bp := p.Apply(mi.unknownOffset).BytesPtr()
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if *bp == nil {
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return nil
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}
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return **bp
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}
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mi.setUnknown = func(p pointer, b pref.RawFields) {
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if p.IsNil() {
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panic("invalid SetUnknown on nil Message")
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}
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bp := p.Apply(mi.unknownOffset).BytesPtr()
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if *bp == nil {
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*bp = new([]byte)
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}
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**bp = b
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}
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default:
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mi.getUnknown = func(pointer) pref.RawFields {
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return nil
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}
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mi.setUnknown = func(p pointer, _ pref.RawFields) {
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if p.IsNil() {
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panic("invalid SetUnknown on nil Message")
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}
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}
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}
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}
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func (mi *MessageInfo) makeExtensionFieldsFunc(t reflect.Type, si structInfo) {
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if si.extensionOffset.IsValid() {
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mi.extensionMap = func(p pointer) *extensionMap {
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if p.IsNil() {
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return (*extensionMap)(nil)
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}
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v := p.Apply(si.extensionOffset).AsValueOf(extensionFieldsType)
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return (*extensionMap)(v.Interface().(*map[int32]ExtensionField))
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}
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} else {
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mi.extensionMap = func(pointer) *extensionMap {
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return (*extensionMap)(nil)
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}
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}
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}
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func (mi *MessageInfo) makeFieldTypes(si structInfo) {
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md := mi.Desc
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fds := md.Fields()
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for i := 0; i < fds.Len(); i++ {
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var ft reflect.Type
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fd := fds.Get(i)
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fs := si.fieldsByNumber[fd.Number()]
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isOneof := fd.ContainingOneof() != nil && !fd.ContainingOneof().IsSynthetic()
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if isOneof {
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fs = si.oneofsByName[fd.ContainingOneof().Name()]
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}
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var isMessage bool
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switch {
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case fs.Type == nil:
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continue // never occurs for officially generated message types
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case isOneof:
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if fd.Enum() != nil || fd.Message() != nil {
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ft = si.oneofWrappersByNumber[fd.Number()].Field(0).Type
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}
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case fd.IsMap():
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if fd.MapValue().Enum() != nil || fd.MapValue().Message() != nil {
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ft = fs.Type.Elem()
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}
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isMessage = fd.MapValue().Message() != nil
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case fd.IsList():
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if fd.Enum() != nil || fd.Message() != nil {
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ft = fs.Type.Elem()
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}
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isMessage = fd.Message() != nil
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case fd.Enum() != nil:
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ft = fs.Type
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if fd.HasPresence() && ft.Kind() == reflect.Ptr {
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ft = ft.Elem()
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}
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case fd.Message() != nil:
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ft = fs.Type
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if fd.IsWeak() {
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ft = nil
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}
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isMessage = true
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}
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if isMessage && ft != nil && ft.Kind() != reflect.Ptr {
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ft = reflect.PtrTo(ft) // never occurs for officially generated message types
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}
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if ft != nil {
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if mi.fieldTypes == nil {
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mi.fieldTypes = make(map[pref.FieldNumber]interface{})
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}
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mi.fieldTypes[fd.Number()] = reflect.Zero(ft).Interface()
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}
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}
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}
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type extensionMap map[int32]ExtensionField
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func (m *extensionMap) Range(f func(pref.FieldDescriptor, pref.Value) bool) {
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if m != nil {
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for _, x := range *m {
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xd := x.Type().TypeDescriptor()
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v := x.Value()
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if xd.IsList() && v.List().Len() == 0 {
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continue
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}
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if !f(xd, v) {
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return
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}
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}
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}
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}
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func (m *extensionMap) Has(xt pref.ExtensionType) (ok bool) {
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if m == nil {
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return false
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}
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xd := xt.TypeDescriptor()
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x, ok := (*m)[int32(xd.Number())]
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if !ok {
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return false
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}
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switch {
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case xd.IsList():
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return x.Value().List().Len() > 0
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case xd.IsMap():
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return x.Value().Map().Len() > 0
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case xd.Message() != nil:
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return x.Value().Message().IsValid()
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}
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return true
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}
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func (m *extensionMap) Clear(xt pref.ExtensionType) {
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delete(*m, int32(xt.TypeDescriptor().Number()))
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}
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func (m *extensionMap) Get(xt pref.ExtensionType) pref.Value {
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xd := xt.TypeDescriptor()
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if m != nil {
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if x, ok := (*m)[int32(xd.Number())]; ok {
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return x.Value()
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}
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}
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return xt.Zero()
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}
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func (m *extensionMap) Set(xt pref.ExtensionType, v pref.Value) {
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xd := xt.TypeDescriptor()
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isValid := true
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switch {
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case !xt.IsValidValue(v):
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isValid = false
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case xd.IsList():
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isValid = v.List().IsValid()
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case xd.IsMap():
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isValid = v.Map().IsValid()
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case xd.Message() != nil:
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isValid = v.Message().IsValid()
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}
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if !isValid {
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panic(fmt.Sprintf("%v: assigning invalid value", xt.TypeDescriptor().FullName()))
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}
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if *m == nil {
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*m = make(map[int32]ExtensionField)
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}
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var x ExtensionField
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x.Set(xt, v)
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(*m)[int32(xd.Number())] = x
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}
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func (m *extensionMap) Mutable(xt pref.ExtensionType) pref.Value {
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xd := xt.TypeDescriptor()
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if xd.Kind() != pref.MessageKind && xd.Kind() != pref.GroupKind && !xd.IsList() && !xd.IsMap() {
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panic("invalid Mutable on field with non-composite type")
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}
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if x, ok := (*m)[int32(xd.Number())]; ok {
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return x.Value()
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}
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v := xt.New()
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m.Set(xt, v)
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return v
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}
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// MessageState is a data structure that is nested as the first field in a
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// concrete message. It provides a way to implement the ProtoReflect method
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// in an allocation-free way without needing to have a shadow Go type generated
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// for every message type. This technique only works using unsafe.
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//
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//
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// Example generated code:
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//
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// type M struct {
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// state protoimpl.MessageState
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//
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// Field1 int32
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// Field2 string
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// Field3 *BarMessage
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// ...
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// }
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//
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// func (m *M) ProtoReflect() protoreflect.Message {
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// mi := &file_fizz_buzz_proto_msgInfos[5]
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// if protoimpl.UnsafeEnabled && m != nil {
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// ms := protoimpl.X.MessageStateOf(Pointer(m))
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// if ms.LoadMessageInfo() == nil {
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// ms.StoreMessageInfo(mi)
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// }
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// return ms
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// }
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// return mi.MessageOf(m)
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// }
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//
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// The MessageState type holds a *MessageInfo, which must be atomically set to
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// the message info associated with a given message instance.
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// By unsafely converting a *M into a *MessageState, the MessageState object
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// has access to all the information needed to implement protobuf reflection.
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// It has access to the message info as its first field, and a pointer to the
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// MessageState is identical to a pointer to the concrete message value.
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//
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//
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// Requirements:
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// • The type M must implement protoreflect.ProtoMessage.
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// • The address of m must not be nil.
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// • The address of m and the address of m.state must be equal,
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// even though they are different Go types.
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type MessageState struct {
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pragma.NoUnkeyedLiterals
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pragma.DoNotCompare
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pragma.DoNotCopy
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atomicMessageInfo *MessageInfo
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}
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type messageState MessageState
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var (
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_ pref.Message = (*messageState)(nil)
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_ unwrapper = (*messageState)(nil)
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)
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// messageDataType is a tuple of a pointer to the message data and
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// a pointer to the message type. It is a generalized way of providing a
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// reflective view over a message instance. The disadvantage of this approach
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// is the need to allocate this tuple of 16B.
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type messageDataType struct {
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p pointer
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mi *MessageInfo
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}
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type (
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messageReflectWrapper messageDataType
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messageIfaceWrapper messageDataType
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)
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var (
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_ pref.Message = (*messageReflectWrapper)(nil)
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_ unwrapper = (*messageReflectWrapper)(nil)
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_ pref.ProtoMessage = (*messageIfaceWrapper)(nil)
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_ unwrapper = (*messageIfaceWrapper)(nil)
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)
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// MessageOf returns a reflective view over a message. The input must be a
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// pointer to a named Go struct. If the provided type has a ProtoReflect method,
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// it must be implemented by calling this method.
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func (mi *MessageInfo) MessageOf(m interface{}) pref.Message {
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if reflect.TypeOf(m) != mi.GoReflectType {
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panic(fmt.Sprintf("type mismatch: got %T, want %v", m, mi.GoReflectType))
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}
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p := pointerOfIface(m)
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if p.IsNil() {
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return mi.nilMessage.Init(mi)
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}
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return &messageReflectWrapper{p, mi}
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}
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func (m *messageReflectWrapper) pointer() pointer { return m.p }
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func (m *messageReflectWrapper) messageInfo() *MessageInfo { return m.mi }
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// Reset implements the v1 proto.Message.Reset method.
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func (m *messageIfaceWrapper) Reset() {
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if mr, ok := m.protoUnwrap().(interface{ Reset() }); ok {
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mr.Reset()
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return
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}
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rv := reflect.ValueOf(m.protoUnwrap())
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if rv.Kind() == reflect.Ptr && !rv.IsNil() {
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rv.Elem().Set(reflect.Zero(rv.Type().Elem()))
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}
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}
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func (m *messageIfaceWrapper) ProtoReflect() pref.Message {
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return (*messageReflectWrapper)(m)
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}
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func (m *messageIfaceWrapper) protoUnwrap() interface{} {
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return m.p.AsIfaceOf(m.mi.GoReflectType.Elem())
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}
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// checkField verifies that the provided field descriptor is valid.
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// Exactly one of the returned values is populated.
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func (mi *MessageInfo) checkField(fd pref.FieldDescriptor) (*fieldInfo, pref.ExtensionType) {
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var fi *fieldInfo
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if n := fd.Number(); 0 < n && int(n) < len(mi.denseFields) {
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fi = mi.denseFields[n]
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} else {
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fi = mi.fields[n]
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}
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if fi != nil {
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if fi.fieldDesc != fd {
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if got, want := fd.FullName(), fi.fieldDesc.FullName(); got != want {
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panic(fmt.Sprintf("mismatching field: got %v, want %v", got, want))
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}
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panic(fmt.Sprintf("mismatching field: %v", fd.FullName()))
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}
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return fi, nil
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}
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if fd.IsExtension() {
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if got, want := fd.ContainingMessage().FullName(), mi.Desc.FullName(); got != want {
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// TODO: Should this be exact containing message descriptor match?
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panic(fmt.Sprintf("extension %v has mismatching containing message: got %v, want %v", fd.FullName(), got, want))
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}
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if !mi.Desc.ExtensionRanges().Has(fd.Number()) {
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panic(fmt.Sprintf("extension %v extends %v outside the extension range", fd.FullName(), mi.Desc.FullName()))
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}
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xtd, ok := fd.(pref.ExtensionTypeDescriptor)
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if !ok {
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panic(fmt.Sprintf("extension %v does not implement protoreflect.ExtensionTypeDescriptor", fd.FullName()))
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}
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return nil, xtd.Type()
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}
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panic(fmt.Sprintf("field %v is invalid", fd.FullName()))
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}
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