220 lines
6.6 KiB
Go
220 lines
6.6 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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"strings"
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"sync"
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"google.golang.org/protobuf/internal/filedesc"
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"google.golang.org/protobuf/internal/strs"
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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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)
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// legacyEnumName returns the name of enums used in legacy code.
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// It is neither the protobuf full name nor the qualified Go name,
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// but rather an odd hybrid of both.
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func legacyEnumName(ed pref.EnumDescriptor) string {
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var protoPkg string
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enumName := string(ed.FullName())
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if fd := ed.ParentFile(); fd != nil {
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protoPkg = string(fd.Package())
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enumName = strings.TrimPrefix(enumName, protoPkg+".")
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}
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if protoPkg == "" {
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return strs.GoCamelCase(enumName)
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}
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return protoPkg + "." + strs.GoCamelCase(enumName)
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}
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// legacyWrapEnum wraps v as a protoreflect.Enum,
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// where v must be a int32 kind and not implement the v2 API already.
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func legacyWrapEnum(v reflect.Value) pref.Enum {
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et := legacyLoadEnumType(v.Type())
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return et.New(pref.EnumNumber(v.Int()))
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}
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var legacyEnumTypeCache sync.Map // map[reflect.Type]protoreflect.EnumType
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// legacyLoadEnumType dynamically loads a protoreflect.EnumType for t,
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// where t must be an int32 kind and not implement the v2 API already.
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func legacyLoadEnumType(t reflect.Type) pref.EnumType {
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// Fast-path: check if a EnumType is cached for this concrete type.
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if et, ok := legacyEnumTypeCache.Load(t); ok {
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return et.(pref.EnumType)
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}
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// Slow-path: derive enum descriptor and initialize EnumType.
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var et pref.EnumType
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ed := LegacyLoadEnumDesc(t)
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et = &legacyEnumType{
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desc: ed,
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goType: t,
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}
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if et, ok := legacyEnumTypeCache.LoadOrStore(t, et); ok {
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return et.(pref.EnumType)
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}
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return et
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}
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type legacyEnumType struct {
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desc pref.EnumDescriptor
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goType reflect.Type
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m sync.Map // map[protoreflect.EnumNumber]proto.Enum
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}
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func (t *legacyEnumType) New(n pref.EnumNumber) pref.Enum {
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if e, ok := t.m.Load(n); ok {
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return e.(pref.Enum)
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}
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e := &legacyEnumWrapper{num: n, pbTyp: t, goTyp: t.goType}
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t.m.Store(n, e)
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return e
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}
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func (t *legacyEnumType) Descriptor() pref.EnumDescriptor {
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return t.desc
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}
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type legacyEnumWrapper struct {
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num pref.EnumNumber
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pbTyp pref.EnumType
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goTyp reflect.Type
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}
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func (e *legacyEnumWrapper) Descriptor() pref.EnumDescriptor {
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return e.pbTyp.Descriptor()
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}
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func (e *legacyEnumWrapper) Type() pref.EnumType {
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return e.pbTyp
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}
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func (e *legacyEnumWrapper) Number() pref.EnumNumber {
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return e.num
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}
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func (e *legacyEnumWrapper) ProtoReflect() pref.Enum {
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return e
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}
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func (e *legacyEnumWrapper) protoUnwrap() interface{} {
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v := reflect.New(e.goTyp).Elem()
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v.SetInt(int64(e.num))
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return v.Interface()
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}
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var (
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_ pref.Enum = (*legacyEnumWrapper)(nil)
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_ unwrapper = (*legacyEnumWrapper)(nil)
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)
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var legacyEnumDescCache sync.Map // map[reflect.Type]protoreflect.EnumDescriptor
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// LegacyLoadEnumDesc returns an EnumDescriptor derived from the Go type,
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// which must be an int32 kind and not implement the v2 API already.
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//
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// This is exported for testing purposes.
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func LegacyLoadEnumDesc(t reflect.Type) pref.EnumDescriptor {
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// Fast-path: check if an EnumDescriptor is cached for this concrete type.
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if ed, ok := legacyEnumDescCache.Load(t); ok {
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return ed.(pref.EnumDescriptor)
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}
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// Slow-path: initialize EnumDescriptor from the raw descriptor.
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ev := reflect.Zero(t).Interface()
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if _, ok := ev.(pref.Enum); ok {
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panic(fmt.Sprintf("%v already implements proto.Enum", t))
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}
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edV1, ok := ev.(enumV1)
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if !ok {
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return aberrantLoadEnumDesc(t)
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}
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b, idxs := edV1.EnumDescriptor()
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var ed pref.EnumDescriptor
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if len(idxs) == 1 {
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ed = legacyLoadFileDesc(b).Enums().Get(idxs[0])
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} else {
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md := legacyLoadFileDesc(b).Messages().Get(idxs[0])
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for _, i := range idxs[1 : len(idxs)-1] {
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md = md.Messages().Get(i)
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}
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ed = md.Enums().Get(idxs[len(idxs)-1])
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}
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if ed, ok := legacyEnumDescCache.LoadOrStore(t, ed); ok {
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return ed.(protoreflect.EnumDescriptor)
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}
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return ed
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}
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var aberrantEnumDescCache sync.Map // map[reflect.Type]protoreflect.EnumDescriptor
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// aberrantLoadEnumDesc returns an EnumDescriptor derived from the Go type,
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// which must not implement protoreflect.Enum or enumV1.
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//
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// If the type does not implement enumV1, then there is no reliable
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// way to derive the original protobuf type information.
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// We are unable to use the global enum registry since it is
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// unfortunately keyed by the protobuf full name, which we also do not know.
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// Thus, this produces some bogus enum descriptor based on the Go type name.
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func aberrantLoadEnumDesc(t reflect.Type) pref.EnumDescriptor {
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// Fast-path: check if an EnumDescriptor is cached for this concrete type.
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if ed, ok := aberrantEnumDescCache.Load(t); ok {
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return ed.(pref.EnumDescriptor)
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}
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// Slow-path: construct a bogus, but unique EnumDescriptor.
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ed := &filedesc.Enum{L2: new(filedesc.EnumL2)}
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ed.L0.FullName = AberrantDeriveFullName(t) // e.g., github_com.user.repo.MyEnum
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ed.L0.ParentFile = filedesc.SurrogateProto3
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ed.L2.Values.List = append(ed.L2.Values.List, filedesc.EnumValue{})
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// TODO: Use the presence of a UnmarshalJSON method to determine proto2?
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vd := &ed.L2.Values.List[0]
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vd.L0.FullName = ed.L0.FullName + "_UNKNOWN" // e.g., github_com.user.repo.MyEnum_UNKNOWN
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vd.L0.ParentFile = ed.L0.ParentFile
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vd.L0.Parent = ed
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// TODO: We could use the String method to obtain some enum value names by
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// starting at 0 and print the enum until it produces invalid identifiers.
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// An exhaustive query is clearly impractical, but can be best-effort.
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if ed, ok := aberrantEnumDescCache.LoadOrStore(t, ed); ok {
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return ed.(pref.EnumDescriptor)
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}
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return ed
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}
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// AberrantDeriveFullName derives a fully qualified protobuf name for the given Go type
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// The provided name is not guaranteed to be stable nor universally unique.
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// It should be sufficiently unique within a program.
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//
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// This is exported for testing purposes.
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func AberrantDeriveFullName(t reflect.Type) pref.FullName {
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sanitize := func(r rune) rune {
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switch {
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case r == '/':
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return '.'
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case 'a' <= r && r <= 'z', 'A' <= r && r <= 'Z', '0' <= r && r <= '9':
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return r
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default:
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return '_'
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}
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}
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prefix := strings.Map(sanitize, t.PkgPath())
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suffix := strings.Map(sanitize, t.Name())
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if suffix == "" {
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suffix = fmt.Sprintf("UnknownX%X", reflect.ValueOf(t).Pointer())
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}
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ss := append(strings.Split(prefix, "."), suffix)
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for i, s := range ss {
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if s == "" || ('0' <= s[0] && s[0] <= '9') {
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ss[i] = "x" + s
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}
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}
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return pref.FullName(strings.Join(ss, "."))
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}
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