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path: root/src/pkg/gob/encode.go
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Diffstat (limited to 'src/pkg/gob/encode.go')
-rw-r--r--src/pkg/gob/encode.go202
1 files changed, 149 insertions, 53 deletions
diff --git a/src/pkg/gob/encode.go b/src/pkg/gob/encode.go
index 2e5ba2487..9190d9203 100644
--- a/src/pkg/gob/encode.go
+++ b/src/pkg/gob/encode.go
@@ -15,7 +15,7 @@ import (
const uint64Size = unsafe.Sizeof(uint64(0))
-// The global execution state of an instance of the encoder.
+// encoderState is the global execution state of an instance of the encoder.
// Field numbers are delta encoded and always increase. The field
// number is initialized to -1 so 0 comes out as delta(1). A delta of
// 0 terminates the structure.
@@ -72,6 +72,7 @@ func (state *encoderState) encodeInt(i int64) {
state.encodeUint(uint64(x))
}
+// encOp is the signature of an encoding operator for a given type.
type encOp func(i *encInstr, state *encoderState, p unsafe.Pointer)
// The 'instructions' of the encoding machine
@@ -82,8 +83,8 @@ type encInstr struct {
offset uintptr // offset in the structure of the field to encode
}
-// Emit a field number and update the state to record its value for delta encoding.
-// If the instruction pointer is nil, do nothing
+// update emits a field number and updates the state to record its value for delta encoding.
+// If the instruction pointer is nil, it does nothing
func (state *encoderState) update(instr *encInstr) {
if instr != nil {
state.encodeUint(uint64(instr.field - state.fieldnum))
@@ -97,6 +98,7 @@ func (state *encoderState) update(instr *encInstr) {
// Otherwise, the output (for a scalar) is the field number, as an encoded integer,
// followed by the field data in its appropriate format.
+// encIndirect dereferences p indir times and returns the result.
func encIndirect(p unsafe.Pointer, indir int) unsafe.Pointer {
for ; indir > 0; indir-- {
p = *(*unsafe.Pointer)(p)
@@ -107,6 +109,7 @@ func encIndirect(p unsafe.Pointer, indir int) unsafe.Pointer {
return p
}
+// encBool encodes the bool with address p as an unsigned 0 or 1.
func encBool(i *encInstr, state *encoderState, p unsafe.Pointer) {
b := *(*bool)(p)
if b || state.sendZero {
@@ -119,6 +122,7 @@ func encBool(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encInt encodes the int with address p.
func encInt(i *encInstr, state *encoderState, p unsafe.Pointer) {
v := int64(*(*int)(p))
if v != 0 || state.sendZero {
@@ -127,6 +131,7 @@ func encInt(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encUint encodes the uint with address p.
func encUint(i *encInstr, state *encoderState, p unsafe.Pointer) {
v := uint64(*(*uint)(p))
if v != 0 || state.sendZero {
@@ -135,6 +140,7 @@ func encUint(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encInt8 encodes the int8 with address p.
func encInt8(i *encInstr, state *encoderState, p unsafe.Pointer) {
v := int64(*(*int8)(p))
if v != 0 || state.sendZero {
@@ -143,6 +149,7 @@ func encInt8(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encUint8 encodes the uint8 with address p.
func encUint8(i *encInstr, state *encoderState, p unsafe.Pointer) {
v := uint64(*(*uint8)(p))
if v != 0 || state.sendZero {
@@ -151,6 +158,7 @@ func encUint8(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encInt16 encodes the int16 with address p.
func encInt16(i *encInstr, state *encoderState, p unsafe.Pointer) {
v := int64(*(*int16)(p))
if v != 0 || state.sendZero {
@@ -159,6 +167,7 @@ func encInt16(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encUint16 encodes the uint16 with address p.
func encUint16(i *encInstr, state *encoderState, p unsafe.Pointer) {
v := uint64(*(*uint16)(p))
if v != 0 || state.sendZero {
@@ -167,6 +176,7 @@ func encUint16(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encInt32 encodes the int32 with address p.
func encInt32(i *encInstr, state *encoderState, p unsafe.Pointer) {
v := int64(*(*int32)(p))
if v != 0 || state.sendZero {
@@ -175,6 +185,7 @@ func encInt32(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encUint encodes the uint32 with address p.
func encUint32(i *encInstr, state *encoderState, p unsafe.Pointer) {
v := uint64(*(*uint32)(p))
if v != 0 || state.sendZero {
@@ -183,6 +194,7 @@ func encUint32(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encInt64 encodes the int64 with address p.
func encInt64(i *encInstr, state *encoderState, p unsafe.Pointer) {
v := *(*int64)(p)
if v != 0 || state.sendZero {
@@ -191,6 +203,7 @@ func encInt64(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encInt64 encodes the uint64 with address p.
func encUint64(i *encInstr, state *encoderState, p unsafe.Pointer) {
v := *(*uint64)(p)
if v != 0 || state.sendZero {
@@ -199,6 +212,7 @@ func encUint64(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encUintptr encodes the uintptr with address p.
func encUintptr(i *encInstr, state *encoderState, p unsafe.Pointer) {
v := uint64(*(*uintptr)(p))
if v != 0 || state.sendZero {
@@ -207,6 +221,7 @@ func encUintptr(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// floatBits returns a uint64 holding the bits of a floating-point number.
// Floating-point numbers are transmitted as uint64s holding the bits
// of the underlying representation. They are sent byte-reversed, with
// the exponent end coming out first, so integer floating point numbers
@@ -223,6 +238,7 @@ func floatBits(f float64) uint64 {
return v
}
+// encFloat32 encodes the float32 with address p.
func encFloat32(i *encInstr, state *encoderState, p unsafe.Pointer) {
f := *(*float32)(p)
if f != 0 || state.sendZero {
@@ -232,6 +248,7 @@ func encFloat32(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encFloat64 encodes the float64 with address p.
func encFloat64(i *encInstr, state *encoderState, p unsafe.Pointer) {
f := *(*float64)(p)
if f != 0 || state.sendZero {
@@ -241,6 +258,7 @@ func encFloat64(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encComplex64 encodes the complex64 with address p.
// Complex numbers are just a pair of floating-point numbers, real part first.
func encComplex64(i *encInstr, state *encoderState, p unsafe.Pointer) {
c := *(*complex64)(p)
@@ -253,6 +271,7 @@ func encComplex64(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encComplex128 encodes the complex128 with address p.
func encComplex128(i *encInstr, state *encoderState, p unsafe.Pointer) {
c := *(*complex128)(p)
if c != 0+0i || state.sendZero {
@@ -264,6 +283,7 @@ func encComplex128(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encUint8Array encodes the byte slice whose header has address p.
// Byte arrays are encoded as an unsigned count followed by the raw bytes.
func encUint8Array(i *encInstr, state *encoderState, p unsafe.Pointer) {
b := *(*[]byte)(p)
@@ -274,6 +294,7 @@ func encUint8Array(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
+// encString encodes the string whose header has address p.
// Strings are encoded as an unsigned count followed by the raw bytes.
func encString(i *encInstr, state *encoderState, p unsafe.Pointer) {
s := *(*string)(p)
@@ -284,14 +305,15 @@ func encString(i *encInstr, state *encoderState, p unsafe.Pointer) {
}
}
-// The end of a struct is marked by a delta field number of 0.
+// encStructTerminator encodes the end of an encoded struct
+// as delta field number of 0.
func encStructTerminator(i *encInstr, state *encoderState, p unsafe.Pointer) {
state.encodeUint(0)
}
// Execution engine
-// The encoder engine is an array of instructions indexed by field number of the encoding
+// encEngine an array of instructions indexed by field number of the encoding
// data, typically a struct. It is executed top to bottom, walking the struct.
type encEngine struct {
instr []encInstr
@@ -299,6 +321,7 @@ type encEngine struct {
const singletonField = 0
+// encodeSingle encodes a single top-level non-struct value.
func (enc *Encoder) encodeSingle(b *bytes.Buffer, engine *encEngine, basep uintptr) {
state := newEncoderState(enc, b)
state.fieldnum = singletonField
@@ -315,6 +338,7 @@ func (enc *Encoder) encodeSingle(b *bytes.Buffer, engine *encEngine, basep uintp
instr.op(instr, state, p)
}
+// encodeStruct encodes a single struct value.
func (enc *Encoder) encodeStruct(b *bytes.Buffer, engine *encEngine, basep uintptr) {
state := newEncoderState(enc, b)
state.fieldnum = -1
@@ -330,6 +354,7 @@ func (enc *Encoder) encodeStruct(b *bytes.Buffer, engine *encEngine, basep uintp
}
}
+// encodeArray encodes the array whose 0th element is at p.
func (enc *Encoder) encodeArray(b *bytes.Buffer, p uintptr, op encOp, elemWid uintptr, elemIndir int, length int) {
state := newEncoderState(enc, b)
state.fieldnum = -1
@@ -349,6 +374,7 @@ func (enc *Encoder) encodeArray(b *bytes.Buffer, p uintptr, op encOp, elemWid ui
}
}
+// encodeReflectValue is a helper for maps. It encodes the value v.
func encodeReflectValue(state *encoderState, v reflect.Value, op encOp, indir int) {
for i := 0; i < indir && v != nil; i++ {
v = reflect.Indirect(v)
@@ -356,9 +382,12 @@ func encodeReflectValue(state *encoderState, v reflect.Value, op encOp, indir in
if v == nil {
errorf("gob: encodeReflectValue: nil element")
}
- op(nil, state, unsafe.Pointer(v.Addr()))
+ op(nil, state, unsafe.Pointer(v.UnsafeAddr()))
}
+// encodeMap encodes a map as unsigned count followed by key:value pairs.
+// Because map internals are not exposed, we must use reflection rather than
+// addresses.
func (enc *Encoder) encodeMap(b *bytes.Buffer, mv *reflect.MapValue, keyOp, elemOp encOp, keyIndir, elemIndir int) {
state := newEncoderState(enc, b)
state.fieldnum = -1
@@ -371,6 +400,7 @@ func (enc *Encoder) encodeMap(b *bytes.Buffer, mv *reflect.MapValue, keyOp, elem
}
}
+// encodeInterface encodes the interface value iv.
// To send an interface, we send a string identifying the concrete type, followed
// by the type identifier (which might require defining that type right now), followed
// by the concrete value. A nil value gets sent as the empty string for the name,
@@ -384,10 +414,10 @@ func (enc *Encoder) encodeInterface(b *bytes.Buffer, iv *reflect.InterfaceValue)
return
}
- typ, _ := indirect(iv.Elem().Type())
- name, ok := concreteTypeToName[typ]
+ ut := userType(iv.Elem().Type())
+ name, ok := concreteTypeToName[ut.base]
if !ok {
- errorf("gob: type not registered for interface: %s", typ)
+ errorf("gob: type not registered for interface: %s", ut.base)
}
// Send the name.
state.encodeUint(uint64(len(name)))
@@ -396,14 +426,14 @@ func (enc *Encoder) encodeInterface(b *bytes.Buffer, iv *reflect.InterfaceValue)
error(err)
}
// Define the type id if necessary.
- enc.sendTypeDescriptor(enc.writer(), state, typ)
+ enc.sendTypeDescriptor(enc.writer(), state, ut)
// Send the type id.
- enc.sendTypeId(state, typ)
+ enc.sendTypeId(state, ut)
// Encode the value into a new buffer. Any nested type definitions
// should be written to b, before the encoded value.
enc.pushWriter(b)
data := new(bytes.Buffer)
- err = enc.encode(data, iv.Elem())
+ err = enc.encode(data, iv.Elem(), ut)
if err != nil {
error(err)
}
@@ -414,7 +444,22 @@ func (enc *Encoder) encodeInterface(b *bytes.Buffer, iv *reflect.InterfaceValue)
}
}
-var encOpMap = []encOp{
+// encGobEncoder encodes a value that implements the GobEncoder interface.
+// The data is sent as a byte array.
+func (enc *Encoder) encodeGobEncoder(b *bytes.Buffer, v reflect.Value, index int) {
+ // TODO: should we catch panics from the called method?
+ // We know it's a GobEncoder, so just call the method directly.
+ data, err := v.Interface().(GobEncoder).GobEncode()
+ if err != nil {
+ error(err)
+ }
+ state := newEncoderState(enc, b)
+ state.fieldnum = -1
+ state.encodeUint(uint64(len(data)))
+ state.b.Write(data)
+}
+
+var encOpTable = [...]encOp{
reflect.Bool: encBool,
reflect.Int: encInt,
reflect.Int8: encInt8,
@@ -434,16 +479,28 @@ var encOpMap = []encOp{
reflect.String: encString,
}
-// Return the encoding op for the base type under rt and
+// encOpFor returns (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) {
- typ, indir := indirect(rt)
- var op encOp
+func (enc *Encoder) encOpFor(rt reflect.Type, inProgress map[reflect.Type]*encOp) (*encOp, int) {
+ ut := userType(rt)
+ // If the type implements GobEncoder, we handle it without further processing.
+ if ut.isGobEncoder {
+ return enc.gobEncodeOpFor(ut)
+ }
+ // 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
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:
@@ -452,40 +509,40 @@ func (enc *Encoder) encOpFor(rt reflect.Type) (encOp, int) {
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
// the iteration.
- v := reflect.NewValue(unsafe.Unreflect(t, unsafe.Pointer((p))))
+ v := reflect.NewValue(unsafe.Unreflect(t, unsafe.Pointer(p)))
mv := reflect.Indirect(v).(*reflect.MapValue)
if !state.sendZero && mv.Len() == 0 {
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.
- enc.getEncEngine(typ)
+ enc.getEncEngine(userType(typ))
info := mustGetTypeInfo(typ)
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
state.update(i)
@@ -496,7 +553,7 @@ func (enc *Encoder) encOpFor(rt reflect.Type) (encOp, int) {
op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
// Interfaces transmit the name and contents of the concrete
// value they contain.
- v := reflect.NewValue(unsafe.Unreflect(t, unsafe.Pointer((p))))
+ v := reflect.NewValue(unsafe.Unreflect(t, unsafe.Pointer(p)))
iv := reflect.Indirect(v).(*reflect.InterfaceValue)
if !state.sendZero && (iv == nil || iv.IsNil()) {
return
@@ -509,21 +566,54 @@ func (enc *Encoder) encOpFor(rt reflect.Type) (encOp, int) {
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)
+// gobEncodeOpFor returns the op for a type that is known to implement
+// GobEncoder.
+func (enc *Encoder) gobEncodeOpFor(ut *userTypeInfo) (*encOp, int) {
+ rt := ut.user
+ if ut.encIndir != 0 {
+ errorf("gob: TODO: can't handle indirection to reach GobEncoder")
+ }
+ index := -1
+ for i := 0; i < rt.NumMethod(); i++ {
+ if rt.Method(i).Name == gobEncodeMethodName {
+ index = i
+ break
+ }
+ }
+ if index < 0 {
+ panic("can't find GobEncode method")
+ }
+ var op encOp
+ op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
+ // TODO: this will need fixing when ut.encIndr != 0.
+ v := reflect.NewValue(unsafe.Unreflect(rt, p))
+ state.update(i)
+ state.enc.encodeGobEncoder(state.b, v, index)
+ }
+ return &op, int(ut.encIndir)
+}
+
+// compileEnc returns the engine to compile the type.
+func (enc *Encoder) compileEnc(ut *userTypeInfo) *encEngine {
+ srt, isStruct := ut.base.(*reflect.StructType)
engine := new(encEngine)
- if isStruct {
- for fieldNum := 0; fieldNum < srt.NumField(); fieldNum++ {
+ seen := make(map[reflect.Type]*encOp)
+ rt := ut.base
+ if ut.isGobEncoder {
+ rt = ut.user
+ }
+ if !ut.isGobEncoder && isStruct {
+ for fieldNum, wireFieldNum := 0, 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, wireFieldNum, indir, uintptr(f.Offset)})
+ wireFieldNum++
}
if srt.NumField() > 0 && len(engine.instr) == 0 {
errorf("type %s has no exported fields", rt)
@@ -531,46 +621,52 @@ func (enc *Encoder) compileEnc(rt reflect.Type) *encEngine {
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
}
+// getEncEngine returns the engine to compile the type.
// typeLock must be held (or we're in initialization and guaranteed single-threaded).
-// The reflection type must have all its indirections processed out.
-func (enc *Encoder) getEncEngine(rt reflect.Type) *encEngine {
- info, err1 := getTypeInfo(rt)
+func (enc *Encoder) getEncEngine(ut *userTypeInfo) *encEngine {
+ info, err1 := getTypeInfo(ut)
if err1 != nil {
error(err1)
}
if info.encoder == nil {
// mark this engine as underway before compiling to handle recursive types.
info.encoder = new(encEngine)
- info.encoder = enc.compileEnc(rt)
+ info.encoder = enc.compileEnc(ut)
}
return info.encoder
}
-// Put this in a function so we can hold the lock only while compiling, not when encoding.
-func (enc *Encoder) lockAndGetEncEngine(rt reflect.Type) *encEngine {
+// lockAndGetEncEngine is a function that locks and compiles.
+// This lets us hold the lock only while compiling, not when encoding.
+func (enc *Encoder) lockAndGetEncEngine(ut *userTypeInfo) *encEngine {
typeLock.Lock()
defer typeLock.Unlock()
- return enc.getEncEngine(rt)
+ return enc.getEncEngine(ut)
}
-func (enc *Encoder) encode(b *bytes.Buffer, value reflect.Value) (err os.Error) {
+func (enc *Encoder) encode(b *bytes.Buffer, value reflect.Value, ut *userTypeInfo) (err os.Error) {
defer catchError(&err)
- // Dereference down to the underlying object.
- rt, indir := indirect(value.Type())
+ engine := enc.lockAndGetEncEngine(ut)
+ indir := ut.indir
+ if ut.isGobEncoder {
+ indir = int(ut.encIndir)
+ if indir != 0 {
+ errorf("TODO: can't handle indirection in GobEncoder value")
+ }
+ }
for i := 0; i < indir; i++ {
value = reflect.Indirect(value)
}
- engine := enc.lockAndGetEncEngine(rt)
- if value.Type().Kind() == reflect.Struct {
- enc.encodeStruct(b, engine, value.Addr())
+ if !ut.isGobEncoder && value.Type().Kind() == reflect.Struct {
+ enc.encodeStruct(b, engine, value.UnsafeAddr())
} else {
- enc.encodeSingle(b, engine, value.Addr())
+ enc.encodeSingle(b, engine, value.UnsafeAddr())
}
return nil
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-07 17:44:16 +0000