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-rw-r--r--src/encoding/gob/type.go913
1 files changed, 913 insertions, 0 deletions
diff --git a/src/encoding/gob/type.go b/src/encoding/gob/type.go
new file mode 100644
index 0000000..3114cb0
--- /dev/null
+++ b/src/encoding/gob/type.go
@@ -0,0 +1,913 @@
+// Copyright 2009 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 gob
+
+import (
+ "encoding"
+ "errors"
+ "fmt"
+ "os"
+ "reflect"
+ "sync"
+ "sync/atomic"
+ "unicode"
+ "unicode/utf8"
+)
+
+// userTypeInfo stores the information associated with a type the user has handed
+// to the package. It's computed once and stored in a map keyed by reflection
+// type.
+type userTypeInfo struct {
+ user reflect.Type // the type the user handed us
+ base reflect.Type // the base type after all indirections
+ indir int // number of indirections to reach the base type
+ externalEnc int // xGob, xBinary, or xText
+ externalDec int // xGob, xBinary or xText
+ encIndir int8 // number of indirections to reach the receiver type; may be negative
+ decIndir int8 // number of indirections to reach the receiver type; may be negative
+}
+
+// externalEncoding bits
+const (
+ xGob = 1 + iota // GobEncoder or GobDecoder
+ xBinary // encoding.BinaryMarshaler or encoding.BinaryUnmarshaler
+ xText // encoding.TextMarshaler or encoding.TextUnmarshaler
+)
+
+var userTypeCache sync.Map // map[reflect.Type]*userTypeInfo
+
+// validUserType returns, and saves, the information associated with user-provided type rt.
+// If the user type is not valid, err will be non-nil. To be used when the error handler
+// is not set up.
+func validUserType(rt reflect.Type) (*userTypeInfo, error) {
+ if ui, ok := userTypeCache.Load(rt); ok {
+ return ui.(*userTypeInfo), nil
+ }
+
+ // Construct a new userTypeInfo and atomically add it to the userTypeCache.
+ // If we lose the race, we'll waste a little CPU and create a little garbage
+ // but return the existing value anyway.
+
+ ut := new(userTypeInfo)
+ ut.base = rt
+ ut.user = rt
+ // A type that is just a cycle of pointers (such as type T *T) cannot
+ // be represented in gobs, which need some concrete data. We use a
+ // cycle detection algorithm from Knuth, Vol 2, Section 3.1, Ex 6,
+ // pp 539-540. As we step through indirections, run another type at
+ // half speed. If they meet up, there's a cycle.
+ slowpoke := ut.base // walks half as fast as ut.base
+ for {
+ pt := ut.base
+ if pt.Kind() != reflect.Pointer {
+ break
+ }
+ ut.base = pt.Elem()
+ if ut.base == slowpoke { // ut.base lapped slowpoke
+ // recursive pointer type.
+ return nil, errors.New("can't represent recursive pointer type " + ut.base.String())
+ }
+ if ut.indir%2 == 0 {
+ slowpoke = slowpoke.Elem()
+ }
+ ut.indir++
+ }
+
+ if ok, indir := implementsInterface(ut.user, gobEncoderInterfaceType); ok {
+ ut.externalEnc, ut.encIndir = xGob, indir
+ } else if ok, indir := implementsInterface(ut.user, binaryMarshalerInterfaceType); ok {
+ ut.externalEnc, ut.encIndir = xBinary, indir
+ }
+
+ // NOTE(rsc): Would like to allow MarshalText here, but results in incompatibility
+ // with older encodings for net.IP. See golang.org/issue/6760.
+ // } else if ok, indir := implementsInterface(ut.user, textMarshalerInterfaceType); ok {
+ // ut.externalEnc, ut.encIndir = xText, indir
+ // }
+
+ if ok, indir := implementsInterface(ut.user, gobDecoderInterfaceType); ok {
+ ut.externalDec, ut.decIndir = xGob, indir
+ } else if ok, indir := implementsInterface(ut.user, binaryUnmarshalerInterfaceType); ok {
+ ut.externalDec, ut.decIndir = xBinary, indir
+ }
+
+ // See note above.
+ // } else if ok, indir := implementsInterface(ut.user, textUnmarshalerInterfaceType); ok {
+ // ut.externalDec, ut.decIndir = xText, indir
+ // }
+
+ ui, _ := userTypeCache.LoadOrStore(rt, ut)
+ return ui.(*userTypeInfo), nil
+}
+
+var (
+ gobEncoderInterfaceType = reflect.TypeOf((*GobEncoder)(nil)).Elem()
+ gobDecoderInterfaceType = reflect.TypeOf((*GobDecoder)(nil)).Elem()
+ binaryMarshalerInterfaceType = reflect.TypeOf((*encoding.BinaryMarshaler)(nil)).Elem()
+ binaryUnmarshalerInterfaceType = reflect.TypeOf((*encoding.BinaryUnmarshaler)(nil)).Elem()
+ textMarshalerInterfaceType = reflect.TypeOf((*encoding.TextMarshaler)(nil)).Elem()
+ textUnmarshalerInterfaceType = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
+)
+
+// implementsInterface reports whether the type implements the
+// gobEncoder/gobDecoder interface.
+// It also returns the number of indirections required to get to the
+// implementation.
+func implementsInterface(typ, gobEncDecType reflect.Type) (success bool, indir int8) {
+ if typ == nil {
+ return
+ }
+ rt := typ
+ // The type might be a pointer and we need to keep
+ // dereferencing to the base type until we find an implementation.
+ for {
+ if rt.Implements(gobEncDecType) {
+ return true, indir
+ }
+ if p := rt; p.Kind() == reflect.Pointer {
+ indir++
+ if indir > 100 { // insane number of indirections
+ return false, 0
+ }
+ rt = p.Elem()
+ continue
+ }
+ break
+ }
+ // No luck yet, but if this is a base type (non-pointer), the pointer might satisfy.
+ if typ.Kind() != reflect.Pointer {
+ // Not a pointer, but does the pointer work?
+ if reflect.PointerTo(typ).Implements(gobEncDecType) {
+ return true, -1
+ }
+ }
+ return false, 0
+}
+
+// userType returns, and saves, the information associated with user-provided type rt.
+// If the user type is not valid, it calls error.
+func userType(rt reflect.Type) *userTypeInfo {
+ ut, err := validUserType(rt)
+ if err != nil {
+ error_(err)
+ }
+ return ut
+}
+
+// A typeId represents a gob Type as an integer that can be passed on the wire.
+// Internally, typeIds are used as keys to a map to recover the underlying type info.
+type typeId int32
+
+var nextId typeId // incremented for each new type we build
+var typeLock sync.Mutex // set while building a type
+const firstUserId = 64 // lowest id number granted to user
+
+type gobType interface {
+ id() typeId
+ setId(id typeId)
+ name() string
+ string() string // not public; only for debugging
+ safeString(seen map[typeId]bool) string
+}
+
+var types = make(map[reflect.Type]gobType)
+var idToType = make(map[typeId]gobType)
+var builtinIdToType map[typeId]gobType // set in init() after builtins are established
+
+func setTypeId(typ gobType) {
+ // When building recursive types, someone may get there before us.
+ if typ.id() != 0 {
+ return
+ }
+ nextId++
+ typ.setId(nextId)
+ idToType[nextId] = typ
+}
+
+func (t typeId) gobType() gobType {
+ if t == 0 {
+ return nil
+ }
+ return idToType[t]
+}
+
+// string returns the string representation of the type associated with the typeId.
+func (t typeId) string() string {
+ if t.gobType() == nil {
+ return "<nil>"
+ }
+ return t.gobType().string()
+}
+
+// Name returns the name of the type associated with the typeId.
+func (t typeId) name() string {
+ if t.gobType() == nil {
+ return "<nil>"
+ }
+ return t.gobType().name()
+}
+
+// CommonType holds elements of all types.
+// It is a historical artifact, kept for binary compatibility and exported
+// only for the benefit of the package's encoding of type descriptors. It is
+// not intended for direct use by clients.
+type CommonType struct {
+ Name string
+ Id typeId
+}
+
+func (t *CommonType) id() typeId { return t.Id }
+
+func (t *CommonType) setId(id typeId) { t.Id = id }
+
+func (t *CommonType) string() string { return t.Name }
+
+func (t *CommonType) safeString(seen map[typeId]bool) string {
+ return t.Name
+}
+
+func (t *CommonType) name() string { return t.Name }
+
+// Create and check predefined types
+// The string for tBytes is "bytes" not "[]byte" to signify its specialness.
+
+var (
+ // Primordial types, needed during initialization.
+ // Always passed as pointers so the interface{} type
+ // goes through without losing its interfaceness.
+ tBool = bootstrapType("bool", (*bool)(nil), 1)
+ tInt = bootstrapType("int", (*int)(nil), 2)
+ tUint = bootstrapType("uint", (*uint)(nil), 3)
+ tFloat = bootstrapType("float", (*float64)(nil), 4)
+ tBytes = bootstrapType("bytes", (*[]byte)(nil), 5)
+ tString = bootstrapType("string", (*string)(nil), 6)
+ tComplex = bootstrapType("complex", (*complex128)(nil), 7)
+ tInterface = bootstrapType("interface", (*any)(nil), 8)
+ // Reserve some Ids for compatible expansion
+ tReserved7 = bootstrapType("_reserved1", (*struct{ r7 int })(nil), 9)
+ tReserved6 = bootstrapType("_reserved1", (*struct{ r6 int })(nil), 10)
+ tReserved5 = bootstrapType("_reserved1", (*struct{ r5 int })(nil), 11)
+ tReserved4 = bootstrapType("_reserved1", (*struct{ r4 int })(nil), 12)
+ tReserved3 = bootstrapType("_reserved1", (*struct{ r3 int })(nil), 13)
+ tReserved2 = bootstrapType("_reserved1", (*struct{ r2 int })(nil), 14)
+ tReserved1 = bootstrapType("_reserved1", (*struct{ r1 int })(nil), 15)
+)
+
+// Predefined because it's needed by the Decoder
+var tWireType = mustGetTypeInfo(reflect.TypeOf(wireType{})).id
+var wireTypeUserInfo *userTypeInfo // userTypeInfo of (*wireType)
+
+func init() {
+ // Some magic numbers to make sure there are no surprises.
+ checkId(16, tWireType)
+ checkId(17, mustGetTypeInfo(reflect.TypeOf(arrayType{})).id)
+ checkId(18, mustGetTypeInfo(reflect.TypeOf(CommonType{})).id)
+ checkId(19, mustGetTypeInfo(reflect.TypeOf(sliceType{})).id)
+ checkId(20, mustGetTypeInfo(reflect.TypeOf(structType{})).id)
+ checkId(21, mustGetTypeInfo(reflect.TypeOf(fieldType{})).id)
+ checkId(23, mustGetTypeInfo(reflect.TypeOf(mapType{})).id)
+
+ builtinIdToType = make(map[typeId]gobType)
+ for k, v := range idToType {
+ builtinIdToType[k] = v
+ }
+
+ // Move the id space upwards to allow for growth in the predefined world
+ // without breaking existing files.
+ if nextId > firstUserId {
+ panic(fmt.Sprintln("nextId too large:", nextId))
+ }
+ nextId = firstUserId
+ registerBasics()
+ wireTypeUserInfo = userType(reflect.TypeOf((*wireType)(nil)))
+}
+
+// Array type
+type arrayType struct {
+ CommonType
+ Elem typeId
+ Len int
+}
+
+func newArrayType(name string) *arrayType {
+ a := &arrayType{CommonType{Name: name}, 0, 0}
+ return a
+}
+
+func (a *arrayType) init(elem gobType, len int) {
+ // Set our type id before evaluating the element's, in case it's our own.
+ setTypeId(a)
+ a.Elem = elem.id()
+ a.Len = len
+}
+
+func (a *arrayType) safeString(seen map[typeId]bool) string {
+ if seen[a.Id] {
+ return a.Name
+ }
+ seen[a.Id] = true
+ return fmt.Sprintf("[%d]%s", a.Len, a.Elem.gobType().safeString(seen))
+}
+
+func (a *arrayType) string() string { return a.safeString(make(map[typeId]bool)) }
+
+// GobEncoder type (something that implements the GobEncoder interface)
+type gobEncoderType struct {
+ CommonType
+}
+
+func newGobEncoderType(name string) *gobEncoderType {
+ g := &gobEncoderType{CommonType{Name: name}}
+ setTypeId(g)
+ return g
+}
+
+func (g *gobEncoderType) safeString(seen map[typeId]bool) string {
+ return g.Name
+}
+
+func (g *gobEncoderType) string() string { return g.Name }
+
+// Map type
+type mapType struct {
+ CommonType
+ Key typeId
+ Elem typeId
+}
+
+func newMapType(name string) *mapType {
+ m := &mapType{CommonType{Name: name}, 0, 0}
+ return m
+}
+
+func (m *mapType) init(key, elem gobType) {
+ // Set our type id before evaluating the element's, in case it's our own.
+ setTypeId(m)
+ m.Key = key.id()
+ m.Elem = elem.id()
+}
+
+func (m *mapType) safeString(seen map[typeId]bool) string {
+ if seen[m.Id] {
+ return m.Name
+ }
+ seen[m.Id] = true
+ key := m.Key.gobType().safeString(seen)
+ elem := m.Elem.gobType().safeString(seen)
+ return fmt.Sprintf("map[%s]%s", key, elem)
+}
+
+func (m *mapType) string() string { return m.safeString(make(map[typeId]bool)) }
+
+// Slice type
+type sliceType struct {
+ CommonType
+ Elem typeId
+}
+
+func newSliceType(name string) *sliceType {
+ s := &sliceType{CommonType{Name: name}, 0}
+ return s
+}
+
+func (s *sliceType) init(elem gobType) {
+ // Set our type id before evaluating the element's, in case it's our own.
+ setTypeId(s)
+ // See the comments about ids in newTypeObject. Only slices and
+ // structs have mutual recursion.
+ if elem.id() == 0 {
+ setTypeId(elem)
+ }
+ s.Elem = elem.id()
+}
+
+func (s *sliceType) safeString(seen map[typeId]bool) string {
+ if seen[s.Id] {
+ return s.Name
+ }
+ seen[s.Id] = true
+ return fmt.Sprintf("[]%s", s.Elem.gobType().safeString(seen))
+}
+
+func (s *sliceType) string() string { return s.safeString(make(map[typeId]bool)) }
+
+// Struct type
+type fieldType struct {
+ Name string
+ Id typeId
+}
+
+type structType struct {
+ CommonType
+ Field []*fieldType
+}
+
+func (s *structType) safeString(seen map[typeId]bool) string {
+ if s == nil {
+ return "<nil>"
+ }
+ if _, ok := seen[s.Id]; ok {
+ return s.Name
+ }
+ seen[s.Id] = true
+ str := s.Name + " = struct { "
+ for _, f := range s.Field {
+ str += fmt.Sprintf("%s %s; ", f.Name, f.Id.gobType().safeString(seen))
+ }
+ str += "}"
+ return str
+}
+
+func (s *structType) string() string { return s.safeString(make(map[typeId]bool)) }
+
+func newStructType(name string) *structType {
+ s := &structType{CommonType{Name: name}, nil}
+ // For historical reasons we set the id here rather than init.
+ // See the comment in newTypeObject for details.
+ setTypeId(s)
+ return s
+}
+
+// newTypeObject allocates a gobType for the reflection type rt.
+// Unless ut represents a GobEncoder, rt should be the base type
+// of ut.
+// This is only called from the encoding side. The decoding side
+// works through typeIds and userTypeInfos alone.
+func newTypeObject(name string, ut *userTypeInfo, rt reflect.Type) (gobType, error) {
+ // Does this type implement GobEncoder?
+ if ut.externalEnc != 0 {
+ return newGobEncoderType(name), nil
+ }
+ var err error
+ var type0, type1 gobType
+ defer func() {
+ if err != nil {
+ delete(types, rt)
+ }
+ }()
+ // Install the top-level type before the subtypes (e.g. struct before
+ // fields) so recursive types can be constructed safely.
+ switch t := rt; t.Kind() {
+ // All basic types are easy: they are predefined.
+ case reflect.Bool:
+ return tBool.gobType(), nil
+
+ case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+ return tInt.gobType(), nil
+
+ case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+ return tUint.gobType(), nil
+
+ case reflect.Float32, reflect.Float64:
+ return tFloat.gobType(), nil
+
+ case reflect.Complex64, reflect.Complex128:
+ return tComplex.gobType(), nil
+
+ case reflect.String:
+ return tString.gobType(), nil
+
+ case reflect.Interface:
+ return tInterface.gobType(), nil
+
+ case reflect.Array:
+ at := newArrayType(name)
+ types[rt] = at
+ type0, err = getBaseType("", t.Elem())
+ if err != nil {
+ return nil, err
+ }
+ // Historical aside:
+ // For arrays, maps, and slices, we set the type id after the elements
+ // are constructed. This is to retain the order of type id allocation after
+ // a fix made to handle recursive types, which changed the order in
+ // which types are built. Delaying the setting in this way preserves
+ // type ids while allowing recursive types to be described. Structs,
+ // done below, were already handling recursion correctly so they
+ // assign the top-level id before those of the field.
+ at.init(type0, t.Len())
+ return at, nil
+
+ case reflect.Map:
+ mt := newMapType(name)
+ types[rt] = mt
+ type0, err = getBaseType("", t.Key())
+ if err != nil {
+ return nil, err
+ }
+ type1, err = getBaseType("", t.Elem())
+ if err != nil {
+ return nil, err
+ }
+ mt.init(type0, type1)
+ return mt, nil
+
+ case reflect.Slice:
+ // []byte == []uint8 is a special case
+ if t.Elem().Kind() == reflect.Uint8 {
+ return tBytes.gobType(), nil
+ }
+ st := newSliceType(name)
+ types[rt] = st
+ type0, err = getBaseType(t.Elem().Name(), t.Elem())
+ if err != nil {
+ return nil, err
+ }
+ st.init(type0)
+ return st, nil
+
+ case reflect.Struct:
+ st := newStructType(name)
+ types[rt] = st
+ idToType[st.id()] = st
+ for i := 0; i < t.NumField(); i++ {
+ f := t.Field(i)
+ if !isSent(&f) {
+ continue
+ }
+ typ := userType(f.Type).base
+ tname := typ.Name()
+ if tname == "" {
+ t := userType(f.Type).base
+ tname = t.String()
+ }
+ gt, err := getBaseType(tname, f.Type)
+ if err != nil {
+ return nil, err
+ }
+ // Some mutually recursive types can cause us to be here while
+ // still defining the element. Fix the element type id here.
+ // We could do this more neatly by setting the id at the start of
+ // building every type, but that would break binary compatibility.
+ if gt.id() == 0 {
+ setTypeId(gt)
+ }
+ st.Field = append(st.Field, &fieldType{f.Name, gt.id()})
+ }
+ return st, nil
+
+ default:
+ return nil, errors.New("gob NewTypeObject can't handle type: " + rt.String())
+ }
+}
+
+// isExported reports whether this is an exported - upper case - name.
+func isExported(name string) bool {
+ rune, _ := utf8.DecodeRuneInString(name)
+ return unicode.IsUpper(rune)
+}
+
+// isSent reports whether this struct field is to be transmitted.
+// It will be transmitted only if it is exported and not a chan or func field
+// or pointer to chan or func.
+func isSent(field *reflect.StructField) bool {
+ if !isExported(field.Name) {
+ return false
+ }
+ // If the field is a chan or func or pointer thereto, don't send it.
+ // That is, treat it like an unexported field.
+ typ := field.Type
+ for typ.Kind() == reflect.Pointer {
+ typ = typ.Elem()
+ }
+ if typ.Kind() == reflect.Chan || typ.Kind() == reflect.Func {
+ return false
+ }
+ return true
+}
+
+// getBaseType returns the Gob type describing the given reflect.Type's base type.
+// typeLock must be held.
+func getBaseType(name string, rt reflect.Type) (gobType, error) {
+ ut := userType(rt)
+ return getType(name, ut, ut.base)
+}
+
+// getType returns the Gob type describing the given reflect.Type.
+// Should be called only when handling GobEncoders/Decoders,
+// which may be pointers. All other types are handled through the
+// base type, never a pointer.
+// typeLock must be held.
+func getType(name string, ut *userTypeInfo, rt reflect.Type) (gobType, error) {
+ typ, present := types[rt]
+ if present {
+ return typ, nil
+ }
+ typ, err := newTypeObject(name, ut, rt)
+ if err == nil {
+ types[rt] = typ
+ }
+ return typ, err
+}
+
+func checkId(want, got typeId) {
+ if want != got {
+ fmt.Fprintf(os.Stderr, "checkId: %d should be %d\n", int(got), int(want))
+ panic("bootstrap type wrong id: " + got.name() + " " + got.string() + " not " + want.string())
+ }
+}
+
+// used for building the basic types; called only from init(). the incoming
+// interface always refers to a pointer.
+func bootstrapType(name string, e any, expect typeId) typeId {
+ rt := reflect.TypeOf(e).Elem()
+ _, present := types[rt]
+ if present {
+ panic("bootstrap type already present: " + name + ", " + rt.String())
+ }
+ typ := &CommonType{Name: name}
+ types[rt] = typ
+ setTypeId(typ)
+ checkId(expect, nextId)
+ userType(rt) // might as well cache it now
+ return nextId
+}
+
+// Representation of the information we send and receive about this type.
+// Each value we send is preceded by its type definition: an encoded int.
+// However, the very first time we send the value, we first send the pair
+// (-id, wireType).
+// For bootstrapping purposes, we assume that the recipient knows how
+// to decode a wireType; it is exactly the wireType struct here, interpreted
+// using the gob rules for sending a structure, except that we assume the
+// ids for wireType and structType etc. are known. The relevant pieces
+// are built in encode.go's init() function.
+// To maintain binary compatibility, if you extend this type, always put
+// the new fields last.
+type wireType struct {
+ ArrayT *arrayType
+ SliceT *sliceType
+ StructT *structType
+ MapT *mapType
+ GobEncoderT *gobEncoderType
+ BinaryMarshalerT *gobEncoderType
+ TextMarshalerT *gobEncoderType
+}
+
+func (w *wireType) string() string {
+ const unknown = "unknown type"
+ if w == nil {
+ return unknown
+ }
+ switch {
+ case w.ArrayT != nil:
+ return w.ArrayT.Name
+ case w.SliceT != nil:
+ return w.SliceT.Name
+ case w.StructT != nil:
+ return w.StructT.Name
+ case w.MapT != nil:
+ return w.MapT.Name
+ case w.GobEncoderT != nil:
+ return w.GobEncoderT.Name
+ case w.BinaryMarshalerT != nil:
+ return w.BinaryMarshalerT.Name
+ case w.TextMarshalerT != nil:
+ return w.TextMarshalerT.Name
+ }
+ return unknown
+}
+
+type typeInfo struct {
+ id typeId
+ encInit sync.Mutex // protects creation of encoder
+ encoder atomic.Pointer[encEngine]
+ wire *wireType
+}
+
+// typeInfoMap is an atomic pointer to map[reflect.Type]*typeInfo.
+// It's updated copy-on-write. Readers just do an atomic load
+// to get the current version of the map. Writers make a full copy of
+// the map and atomically update the pointer to point to the new map.
+// Under heavy read contention, this is significantly faster than a map
+// protected by a mutex.
+var typeInfoMap atomic.Value
+
+func lookupTypeInfo(rt reflect.Type) *typeInfo {
+ m, _ := typeInfoMap.Load().(map[reflect.Type]*typeInfo)
+ return m[rt]
+}
+
+func getTypeInfo(ut *userTypeInfo) (*typeInfo, error) {
+ rt := ut.base
+ if ut.externalEnc != 0 {
+ // We want the user type, not the base type.
+ rt = ut.user
+ }
+ if info := lookupTypeInfo(rt); info != nil {
+ return info, nil
+ }
+ return buildTypeInfo(ut, rt)
+}
+
+// buildTypeInfo constructs the type information for the type
+// and stores it in the type info map.
+func buildTypeInfo(ut *userTypeInfo, rt reflect.Type) (*typeInfo, error) {
+ typeLock.Lock()
+ defer typeLock.Unlock()
+
+ if info := lookupTypeInfo(rt); info != nil {
+ return info, nil
+ }
+
+ gt, err := getBaseType(rt.Name(), rt)
+ if err != nil {
+ return nil, err
+ }
+ info := &typeInfo{id: gt.id()}
+
+ if ut.externalEnc != 0 {
+ userType, err := getType(rt.Name(), ut, rt)
+ if err != nil {
+ return nil, err
+ }
+ gt := userType.id().gobType().(*gobEncoderType)
+ switch ut.externalEnc {
+ case xGob:
+ info.wire = &wireType{GobEncoderT: gt}
+ case xBinary:
+ info.wire = &wireType{BinaryMarshalerT: gt}
+ case xText:
+ info.wire = &wireType{TextMarshalerT: gt}
+ }
+ rt = ut.user
+ } else {
+ t := info.id.gobType()
+ switch typ := rt; typ.Kind() {
+ case reflect.Array:
+ info.wire = &wireType{ArrayT: t.(*arrayType)}
+ case reflect.Map:
+ info.wire = &wireType{MapT: t.(*mapType)}
+ case reflect.Slice:
+ // []byte == []uint8 is a special case handled separately
+ if typ.Elem().Kind() != reflect.Uint8 {
+ info.wire = &wireType{SliceT: t.(*sliceType)}
+ }
+ case reflect.Struct:
+ info.wire = &wireType{StructT: t.(*structType)}
+ }
+ }
+
+ // Create new map with old contents plus new entry.
+ newm := make(map[reflect.Type]*typeInfo)
+ m, _ := typeInfoMap.Load().(map[reflect.Type]*typeInfo)
+ for k, v := range m {
+ newm[k] = v
+ }
+ newm[rt] = info
+ typeInfoMap.Store(newm)
+ return info, nil
+}
+
+// Called only when a panic is acceptable and unexpected.
+func mustGetTypeInfo(rt reflect.Type) *typeInfo {
+ t, err := getTypeInfo(userType(rt))
+ if err != nil {
+ panic("getTypeInfo: " + err.Error())
+ }
+ return t
+}
+
+// GobEncoder is the interface describing data that provides its own
+// representation for encoding values for transmission to a GobDecoder.
+// A type that implements GobEncoder and GobDecoder has complete
+// control over the representation of its data and may therefore
+// contain things such as private fields, channels, and functions,
+// which are not usually transmissible in gob streams.
+//
+// Note: Since gobs can be stored permanently, it is good design
+// to guarantee the encoding used by a GobEncoder is stable as the
+// software evolves. For instance, it might make sense for GobEncode
+// to include a version number in the encoding.
+type GobEncoder interface {
+ // GobEncode returns a byte slice representing the encoding of the
+ // receiver for transmission to a GobDecoder, usually of the same
+ // concrete type.
+ GobEncode() ([]byte, error)
+}
+
+// GobDecoder is the interface describing data that provides its own
+// routine for decoding transmitted values sent by a GobEncoder.
+type GobDecoder interface {
+ // GobDecode overwrites the receiver, which must be a pointer,
+ // with the value represented by the byte slice, which was written
+ // by GobEncode, usually for the same concrete type.
+ GobDecode([]byte) error
+}
+
+var (
+ nameToConcreteType sync.Map // map[string]reflect.Type
+ concreteTypeToName sync.Map // map[reflect.Type]string
+)
+
+// RegisterName is like Register but uses the provided name rather than the
+// type's default.
+func RegisterName(name string, value any) {
+ if name == "" {
+ // reserved for nil
+ panic("attempt to register empty name")
+ }
+
+ ut := userType(reflect.TypeOf(value))
+
+ // Check for incompatible duplicates. The name must refer to the
+ // same user type, and vice versa.
+
+ // Store the name and type provided by the user....
+ if t, dup := nameToConcreteType.LoadOrStore(name, reflect.TypeOf(value)); dup && t != ut.user {
+ panic(fmt.Sprintf("gob: registering duplicate types for %q: %s != %s", name, t, ut.user))
+ }
+
+ // but the flattened type in the type table, since that's what decode needs.
+ if n, dup := concreteTypeToName.LoadOrStore(ut.base, name); dup && n != name {
+ nameToConcreteType.Delete(name)
+ panic(fmt.Sprintf("gob: registering duplicate names for %s: %q != %q", ut.user, n, name))
+ }
+}
+
+// Register records a type, identified by a value for that type, under its
+// internal type name. That name will identify the concrete type of a value
+// sent or received as an interface variable. Only types that will be
+// transferred as implementations of interface values need to be registered.
+// Expecting to be used only during initialization, it panics if the mapping
+// between types and names is not a bijection.
+func Register(value any) {
+ // Default to printed representation for unnamed types
+ rt := reflect.TypeOf(value)
+ name := rt.String()
+
+ // But for named types (or pointers to them), qualify with import path (but see inner comment).
+ // Dereference one pointer looking for a named type.
+ star := ""
+ if rt.Name() == "" {
+ if pt := rt; pt.Kind() == reflect.Pointer {
+ star = "*"
+ // NOTE: The following line should be rt = pt.Elem() to implement
+ // what the comment above claims, but fixing it would break compatibility
+ // with existing gobs.
+ //
+ // Given package p imported as "full/p" with these definitions:
+ // package p
+ // type T1 struct { ... }
+ // this table shows the intended and actual strings used by gob to
+ // name the types:
+ //
+ // Type Correct string Actual string
+ //
+ // T1 full/p.T1 full/p.T1
+ // *T1 *full/p.T1 *p.T1
+ //
+ // The missing full path cannot be fixed without breaking existing gob decoders.
+ rt = pt
+ }
+ }
+ if rt.Name() != "" {
+ if rt.PkgPath() == "" {
+ name = star + rt.Name()
+ } else {
+ name = star + rt.PkgPath() + "." + rt.Name()
+ }
+ }
+
+ RegisterName(name, value)
+}
+
+func registerBasics() {
+ Register(int(0))
+ Register(int8(0))
+ Register(int16(0))
+ Register(int32(0))
+ Register(int64(0))
+ Register(uint(0))
+ Register(uint8(0))
+ Register(uint16(0))
+ Register(uint32(0))
+ Register(uint64(0))
+ Register(float32(0))
+ Register(float64(0))
+ Register(complex64(0i))
+ Register(complex128(0i))
+ Register(uintptr(0))
+ Register(false)
+ Register("")
+ Register([]byte(nil))
+ Register([]int(nil))
+ Register([]int8(nil))
+ Register([]int16(nil))
+ Register([]int32(nil))
+ Register([]int64(nil))
+ Register([]uint(nil))
+ Register([]uint8(nil))
+ Register([]uint16(nil))
+ Register([]uint32(nil))
+ Register([]uint64(nil))
+ Register([]float32(nil))
+ Register([]float64(nil))
+ Register([]complex64(nil))
+ Register([]complex128(nil))
+ Register([]uintptr(nil))
+ Register([]bool(nil))
+ Register([]string(nil))
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-09-18 04:30:34 +0000