var data struct {
a int
}
- instr := &decInstr{decOpMap[reflect.Int], 6, 0, 0, ovfl}
+ instr := &decInstr{decOpTable[reflect.Int], 6, 0, 0, ovfl}
state := newDecodeStateFromData(signedResult)
execDec("int", instr, state, t, unsafe.Pointer(&data))
if data.a != 17 {
var data struct {
a uint
}
- instr := &decInstr{decOpMap[reflect.Uint], 6, 0, 0, ovfl}
+ instr := &decInstr{decOpTable[reflect.Uint], 6, 0, 0, ovfl}
state := newDecodeStateFromData(unsignedResult)
execDec("uint", instr, state, t, unsafe.Pointer(&data))
if data.a != 17 {
var data struct {
a uintptr
}
- instr := &decInstr{decOpMap[reflect.Uintptr], 6, 0, 0, ovfl}
+ instr := &decInstr{decOpTable[reflect.Uintptr], 6, 0, 0, ovfl}
state := newDecodeStateFromData(unsignedResult)
execDec("uintptr", instr, state, t, unsafe.Pointer(&data))
if data.a != 17 {
var data struct {
a complex64
}
- instr := &decInstr{decOpMap[reflect.Complex64], 6, 0, 0, ovfl}
+ instr := &decInstr{decOpTable[reflect.Complex64], 6, 0, 0, ovfl}
state := newDecodeStateFromData(complexResult)
execDec("complex", instr, state, t, unsafe.Pointer(&data))
if data.a != 17+19i {
var data struct {
a complex128
}
- instr := &decInstr{decOpMap[reflect.Complex128], 6, 0, 0, ovfl}
+ instr := &decInstr{decOpTable[reflect.Complex128], 6, 0, 0, ovfl}
state := newDecodeStateFromData(complexResult)
execDec("complex", instr, state, t, unsafe.Pointer(&data))
if data.a != 17+19i {
}
// Index by Go types.
-var decOpMap = []decOp{
+var decOpTable = [...]decOp{
reflect.Bool: decBool,
reflect.Int8: decInt8,
reflect.Int16: decInt16,
// Return the decoding op for the base type under rt and
// the indirection count to reach it.
-func (dec *Decoder) decOpFor(wireId typeId, rt reflect.Type, name string) (decOp, int) {
+func (dec *Decoder) decOpFor(wireId typeId, rt reflect.Type, name string, inProgress map[reflect.Type]*decOp) (*decOp, int) {
ut := userType(rt)
+ // If this type is already in progress, it's a recursive type (e.g. map[string]*T).
+ // Return the pointer to the op we're already building.
+ if opPtr := inProgress[rt]; opPtr != nil {
+ return opPtr, ut.indir
+ }
typ := ut.base
indir := ut.indir
var op decOp
k := typ.Kind()
- if int(k) < len(decOpMap) {
- op = decOpMap[k]
+ if int(k) < len(decOpTable) {
+ op = decOpTable[k]
}
if op == nil {
+ inProgress[rt] = &op
// Special cases
switch t := typ.(type) {
case *reflect.ArrayType:
name = "element of " + name
elemId := dec.wireType[wireId].ArrayT.Elem
- elemOp, elemIndir := dec.decOpFor(elemId, t.Elem(), name)
+ elemOp, elemIndir := dec.decOpFor(elemId, t.Elem(), name, inProgress)
ovfl := overflow(name)
op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
- state.dec.decodeArray(t, state, uintptr(p), elemOp, t.Elem().Size(), t.Len(), i.indir, elemIndir, ovfl)
+ state.dec.decodeArray(t, state, uintptr(p), *elemOp, t.Elem().Size(), t.Len(), i.indir, elemIndir, ovfl)
}
case *reflect.MapType:
name = "element of " + name
keyId := dec.wireType[wireId].MapT.Key
elemId := dec.wireType[wireId].MapT.Elem
- keyOp, keyIndir := dec.decOpFor(keyId, t.Key(), name)
- elemOp, elemIndir := dec.decOpFor(elemId, t.Elem(), name)
+ keyOp, keyIndir := dec.decOpFor(keyId, t.Key(), name, inProgress)
+ elemOp, elemIndir := dec.decOpFor(elemId, t.Elem(), name, inProgress)
ovfl := overflow(name)
op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
up := unsafe.Pointer(p)
- state.dec.decodeMap(t, state, uintptr(up), keyOp, elemOp, i.indir, keyIndir, elemIndir, ovfl)
+ state.dec.decodeMap(t, state, uintptr(up), *keyOp, *elemOp, i.indir, keyIndir, elemIndir, ovfl)
}
case *reflect.SliceType:
} else {
elemId = dec.wireType[wireId].SliceT.Elem
}
- elemOp, elemIndir := dec.decOpFor(elemId, t.Elem(), name)
+ elemOp, elemIndir := dec.decOpFor(elemId, t.Elem(), name, inProgress)
ovfl := overflow(name)
op = func(i *decInstr, state *decodeState, p unsafe.Pointer) {
- state.dec.decodeSlice(t, state, uintptr(p), elemOp, t.Elem().Size(), i.indir, elemIndir, ovfl)
+ state.dec.decodeSlice(t, state, uintptr(p), *elemOp, t.Elem().Size(), i.indir, elemIndir, ovfl)
}
case *reflect.StructType:
if op == nil {
errorf("gob: decode can't handle type %s", rt.String())
}
- return op, indir
+ return &op, indir
}
// Return the decoding op for a field that has no destination.
// Are these two gob Types compatible?
// Answers the question for basic types, arrays, and slices.
// Structs are considered ok; fields will be checked later.
-func (dec *Decoder) compatibleType(fr reflect.Type, fw typeId) bool {
+func (dec *Decoder) compatibleType(fr reflect.Type, fw typeId, inProgress map[reflect.Type]typeId) bool {
+ if rhs, ok := inProgress[fr]; ok {
+ return rhs == fw
+ }
+ inProgress[fr] = fw
fr = userType(fr).base
switch t := fr.(type) {
default:
- // map, chan, etc: cannot handle.
+ // chan, etc: cannot handle.
return false
case *reflect.BoolType:
return fw == tBool
return false
}
array := wire.ArrayT
- return t.Len() == array.Len && dec.compatibleType(t.Elem(), array.Elem)
+ return t.Len() == array.Len && dec.compatibleType(t.Elem(), array.Elem, inProgress)
case *reflect.MapType:
wire, ok := dec.wireType[fw]
if !ok || wire.MapT == nil {
return false
}
MapType := wire.MapT
- return dec.compatibleType(t.Key(), MapType.Key) && dec.compatibleType(t.Elem(), MapType.Elem)
+ return dec.compatibleType(t.Key(), MapType.Key, inProgress) && dec.compatibleType(t.Elem(), MapType.Elem, inProgress)
case *reflect.SliceType:
// Is it an array of bytes?
if t.Elem().Kind() == reflect.Uint8 {
sw = dec.wireType[fw].SliceT
}
elem := userType(t.Elem()).base
- return sw != nil && dec.compatibleType(elem, sw.Elem)
+ return sw != nil && dec.compatibleType(elem, sw.Elem, inProgress)
case *reflect.StructType:
return true
}
engine = new(decEngine)
engine.instr = make([]decInstr, 1) // one item
name := rt.String() // best we can do
- if !dec.compatibleType(rt, remoteId) {
+ if !dec.compatibleType(rt, remoteId, make(map[reflect.Type]typeId)) {
return nil, os.ErrorString("gob: wrong type received for local value " + name + ": " + dec.typeString(remoteId))
}
- op, indir := dec.decOpFor(remoteId, rt, name)
+ op, indir := dec.decOpFor(remoteId, rt, name, make(map[reflect.Type]*decOp))
ovfl := os.ErrorString(`value for "` + name + `" out of range`)
- engine.instr[singletonField] = decInstr{op, singletonField, indir, 0, ovfl}
+ engine.instr[singletonField] = decInstr{*op, singletonField, indir, 0, ovfl}
engine.numInstr = 1
return
}
}
engine = new(decEngine)
engine.instr = make([]decInstr, len(wireStruct.Field))
+ seen := make(map[reflect.Type]*decOp)
// Loop over the fields of the wire type.
for fieldnum := 0; fieldnum < len(wireStruct.Field); fieldnum++ {
wireField := wireStruct.Field[fieldnum]
engine.instr[fieldnum] = decInstr{op, fieldnum, 0, 0, ovfl}
continue
}
- if !dec.compatibleType(localField.Type, wireField.Id) {
+ if !dec.compatibleType(localField.Type, wireField.Id, make(map[reflect.Type]typeId)) {
errorf("gob: wrong type (%s) for received field %s.%s", localField.Type, wireStruct.Name, wireField.Name)
}
- op, indir := dec.decOpFor(wireField.Id, localField.Type, localField.Name)
- engine.instr[fieldnum] = decInstr{op, fieldnum, indir, uintptr(localField.Offset), ovfl}
+ op, indir := dec.decOpFor(wireField.Id, localField.Type, localField.Name, seen)
+ engine.instr[fieldnum] = decInstr{*op, fieldnum, indir, uintptr(localField.Offset), ovfl}
engine.numInstr++
}
return
default:
panic("gob: unknown size of int/uint")
}
- decOpMap[reflect.Int] = iop
- decOpMap[reflect.Uint] = uop
+ decOpTable[reflect.Int] = iop
+ decOpTable[reflect.Uint] = uop
// Finally uintptr
switch reflect.Typeof(uintptr(0)).Bits() {
default:
panic("gob: unknown size of uintptr")
}
- decOpMap[reflect.Uintptr] = uop
+ decOpTable[reflect.Uintptr] = uop
}
}
}
-var encOpMap = []encOp{
+var encOpTable = [...]encOp{
reflect.Bool: encBool,
reflect.Int: encInt,
reflect.Int8: encInt8,
reflect.String: encString,
}
-// Return the encoding op for the base type under rt and
+// Return (a pointer to) the encoding op for the base type under rt and
// the indirection count to reach it.
-func (enc *Encoder) encOpFor(rt reflect.Type) (encOp, int) {
+func (enc *Encoder) encOpFor(rt reflect.Type, inProgress map[reflect.Type]*encOp) (*encOp, int) {
ut := userType(rt)
+ // If this type is already in progress, it's a recursive type (e.g. map[string]*T).
+ // Return the pointer to the op we're already building.
+ if opPtr := inProgress[rt]; opPtr != nil {
+ return opPtr, ut.indir
+ }
typ := ut.base
indir := ut.indir
- var op encOp
k := typ.Kind()
- if int(k) < len(encOpMap) {
- op = encOpMap[k]
+ var op encOp
+ if int(k) < len(encOpTable) {
+ op = encOpTable[k]
}
if op == nil {
+ inProgress[rt] = &op
// Special cases
switch t := typ.(type) {
case *reflect.SliceType:
break
}
// Slices have a header; we decode it to find the underlying array.
- elemOp, indir := enc.encOpFor(t.Elem())
+ elemOp, indir := enc.encOpFor(t.Elem(), inProgress)
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
slice := (*reflect.SliceHeader)(p)
if !state.sendZero && slice.Len == 0 {
return
}
state.update(i)
- state.enc.encodeArray(state.b, slice.Data, elemOp, t.Elem().Size(), indir, int(slice.Len))
+ state.enc.encodeArray(state.b, slice.Data, *elemOp, t.Elem().Size(), indir, int(slice.Len))
}
case *reflect.ArrayType:
// True arrays have size in the type.
- elemOp, indir := enc.encOpFor(t.Elem())
+ elemOp, indir := enc.encOpFor(t.Elem(), inProgress)
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
state.update(i)
- state.enc.encodeArray(state.b, uintptr(p), elemOp, t.Elem().Size(), indir, t.Len())
+ state.enc.encodeArray(state.b, uintptr(p), *elemOp, t.Elem().Size(), indir, t.Len())
}
case *reflect.MapType:
- keyOp, keyIndir := enc.encOpFor(t.Key())
- elemOp, elemIndir := enc.encOpFor(t.Elem())
+ keyOp, keyIndir := enc.encOpFor(t.Key(), inProgress)
+ elemOp, elemIndir := enc.encOpFor(t.Elem(), inProgress)
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
// Maps cannot be accessed by moving addresses around the way
// that slices etc. can. We must recover a full reflection value for
return
}
state.update(i)
- state.enc.encodeMap(state.b, mv, keyOp, elemOp, keyIndir, elemIndir)
+ state.enc.encodeMap(state.b, mv, *keyOp, *elemOp, keyIndir, elemIndir)
}
case *reflect.StructType:
// Generate a closure that calls out to the engine for the nested type.
if op == nil {
errorf("gob enc: can't happen: encode type %s", rt.String())
}
- return op, indir
+ return &op, indir
}
// The local Type was compiled from the actual value, so we know it's compatible.
func (enc *Encoder) compileEnc(rt reflect.Type) *encEngine {
srt, isStruct := rt.(*reflect.StructType)
engine := new(encEngine)
+ seen := make(map[reflect.Type]*encOp)
if isStruct {
for fieldNum := 0; fieldNum < srt.NumField(); fieldNum++ {
f := srt.Field(fieldNum)
if !isExported(f.Name) {
continue
}
- op, indir := enc.encOpFor(f.Type)
- engine.instr = append(engine.instr, encInstr{op, fieldNum, indir, uintptr(f.Offset)})
+ op, indir := enc.encOpFor(f.Type, seen)
+ engine.instr = append(engine.instr, encInstr{*op, fieldNum, indir, uintptr(f.Offset)})
}
if srt.NumField() > 0 && len(engine.instr) == 0 {
errorf("type %s has no exported fields", rt)
engine.instr = append(engine.instr, encInstr{encStructTerminator, 0, 0, 0})
} else {
engine.instr = make([]encInstr, 1)
- op, indir := enc.encOpFor(rt)
- engine.instr[0] = encInstr{op, singletonField, indir, 0} // offset is zero
+ op, indir := enc.encOpFor(rt, seen)
+ engine.instr[0] = encInstr{*op, singletonField, indir, 0} // offset is zero
}
return engine
}
}
}
+func TestRecursiveMapType(t *testing.T) {
+ type recursiveMap map[string]recursiveMap
+ r1 := recursiveMap{"A": recursiveMap{"B": nil, "C": nil}, "D": nil}
+ r2 := make(recursiveMap)
+ if err := encAndDec(r1, &r2); err != nil {
+ t.Error(err)
+ }
+}
+
+func TestRecursiveSliceType(t *testing.T) {
+ type recursiveSlice []recursiveSlice
+ r1 := recursiveSlice{0: recursiveSlice{0: nil}, 1: nil}
+ r2 := make(recursiveSlice, 0)
+ if err := encAndDec(r1, &r2); err != nil {
+ t.Error(err)
+ }
+}
+
// Regression test for bug: must send zero values inside arrays
func TestDefaultsInArray(t *testing.T) {
type Type7 struct {
// 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.
- // TODO: still need to deal with self-referential non-structs such
- // as type T map[string]T but that is a larger undertaking - and can
- // be useful, not always erroneous.
slowpoke := ut.base // walks half as fast as ut.base
for {
pt, ok := ut.base.(*reflect.PtrType)
Len int
}
-func newArrayType(name string, elem gobType, length int) *arrayType {
- a := &arrayType{CommonType{Name: name}, elem.id(), length}
- setTypeId(a)
+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
Elem typeId
}
-func newMapType(name string, key, elem gobType) *mapType {
- m := &mapType{CommonType{Name: name}, key.id(), elem.id()}
- setTypeId(m)
+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
Elem typeId
}
-func newSliceType(name string, elem gobType) *sliceType {
- s := &sliceType{CommonType{Name: name}, elem.id()}
- setTypeId(s)
+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)
+ s.Elem = elem.id()
+}
+
func (s *sliceType) safeString(seen map[typeId]bool) string {
if seen[s.Id] {
return s.Name
func newStructType(name string) *structType {
s := &structType{CommonType{Name: name}, nil}
+ // For historical reasons we set the id here rather than init.
+ // Se the comment in newTypeObject for details.
setTypeId(s)
return s
}
+func (s *structType) init(field []*fieldType) {
+ s.Field = field
+}
+
func newTypeObject(name string, rt reflect.Type) (gobType, os.Error) {
+ var err os.Error
+ var type0, type1 gobType
+ defer func() {
+ if err != nil {
+ types[rt] = nil, false
+ }
+ }()
+ // Install the top-level type before the subtypes (e.g. struct before
+ // fields) so recursive types can be constructed safely.
switch t := rt.(type) {
// All basic types are easy: they are predefined.
case *reflect.BoolType:
return tInterface.gobType(), nil
case *reflect.ArrayType:
- gt, err := getType("", t.Elem())
+ at := newArrayType(name)
+ types[rt] = at
+ type0, err = getType("", t.Elem())
if err != nil {
return nil, err
}
- return newArrayType(name, gt, t.Len()), nil
+ // 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.MapType:
- kt, err := getType("", t.Key())
+ mt := newMapType(name)
+ types[rt] = mt
+ type0, err = getType("", t.Key())
if err != nil {
return nil, err
}
- vt, err := getType("", t.Elem())
+ type1, err = getType("", t.Elem())
if err != nil {
return nil, err
}
- return newMapType(name, kt, vt), nil
+ mt.init(type0, type1)
+ return mt, nil
case *reflect.SliceType:
// []byte == []uint8 is a special case
if t.Elem().Kind() == reflect.Uint8 {
return tBytes.gobType(), nil
}
- gt, err := getType(t.Elem().Name(), t.Elem())
+ st := newSliceType(name)
+ types[rt] = st
+ type0, err = getType(t.Elem().Name(), t.Elem())
if err != nil {
return nil, err
}
- return newSliceType(name, gt), nil
+ st.init(type0)
+ return st, nil
case *reflect.StructType:
- // Install the struct type itself before the fields so recursive
- // structures can be constructed safely.
- strType := newStructType(name)
- types[rt] = strType
- idToType[strType.id()] = strType
+ st := newStructType(name)
+ types[rt] = st
+ idToType[st.id()] = st
field := make([]*fieldType, t.NumField())
for i := 0; i < t.NumField(); i++ {
f := t.Field(i)
}
field[i] = &fieldType{f.Name, gt.id()}
}
- strType.Field = field
- return strType, nil
+ st.init(field)
+ return st, nil
default:
return nil, os.ErrorString("gob NewTypeObject can't handle type: " + rt.String())
// 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 are known. The relevant pieces
+// 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.