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// 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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} |