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encode and decode for nested structures.

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fix a bug in delta encoding: only update the delta-base if something is marshaled.

R=rsc
DELTA=154  (94 added, 56 deleted, 4 changed)
OCL=31069
CL=31071
This commit is contained in:
Rob Pike 2009-07-02 13:43:47 -07:00
parent 1ca1e1befa
commit 77baac11e1
3 changed files with 96 additions and 58 deletions
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68
src/pkg/gob/decode.go
View file

@ -279,6 +279,31 @@ type decEngine struct {
instr []decInstr
}
func (engine *decEngine) decodeStruct(r io.Reader, p uintptr) os.Error {
state := new(DecState);
state.r = r;
state.base = p;
state.fieldnum = -1;
for state.err == nil {
delta := int(DecodeUint(state));
if state.err != nil || delta == 0 { // struct terminator is zero delta fieldnum
break
}
fieldnum := state.fieldnum + delta;
if fieldnum >= len(engine.instr) {
panicln("TODO(r): need to handle unknown data");
}
instr := &engine.instr[fieldnum];
p := unsafe.Pointer(state.base+instr.offset);
if instr.indir > 1 {
p = decIndirect(p, instr.indir);
}
instr.op(instr, state, p);
state.fieldnum = fieldnum;
}
return state.err
}
var decEngineMap = make(map[reflect.Type] *decEngine)
var decOpMap = map[int] decOp {
reflect.BoolKind: decBool,
@ -298,6 +323,8 @@ var decOpMap = map[int] decOp {
reflect.StringKind: decString,
}
func getDecEngine(rt reflect.Type) *decEngine
func decOpFor(typ reflect.Type) decOp {
op, ok := decOpMap[typ.Kind()];
if !ok {
@ -309,6 +336,13 @@ func decOpFor(typ reflect.Type) decOp {
op = decUint8Array
}
}
if typ.Kind() == reflect.StructKind {
// Generate a closure that calls out to the engine for the nested type.
engine := getDecEngine(typ);
op = func(i *decInstr, state *DecState, p unsafe.Pointer) {
state.err = engine.decodeStruct(state.r, uintptr(p))
};
}
}
if op == nil {
panicln("decode can't handle type", typ.String());
@ -355,35 +389,6 @@ func getDecEngine(rt reflect.Type) *decEngine {
return engine;
}
func (engine *decEngine) decode(r io.Reader, v reflect.Value) os.Error {
sv, ok := v.(reflect.StructValue);
if !ok {
panicln("decoder can't handle non-struct values yet");
}
state := new(DecState);
state.r = r;
state.base = uintptr(sv.Addr());
state.fieldnum = -1;
for state.err == nil {
delta := int(DecodeUint(state));
if state.err != nil || delta == 0 { // struct terminator is zero delta fieldnum
break
}
fieldnum := state.fieldnum + delta;
if fieldnum >= len(engine.instr) {
panicln("TODO(r): need to handle unknown data");
}
instr := &engine.instr[fieldnum];
p := unsafe.Pointer(state.base+instr.offset);
if instr.indir > 1 {
p = decIndirect(p, instr.indir);
}
instr.op(instr, state, p);
state.fieldnum = fieldnum;
}
return state.err
}
func Decode(r io.Reader, e interface{}) os.Error {
// Dereference down to the underlying object.
rt := reflect.Typeof(e);
@ -396,8 +401,11 @@ func Decode(r io.Reader, e interface{}) os.Error {
rt = pt.Sub();
v = reflect.Indirect(v);
}
if v.Kind() != reflect.StructKind {
return os.ErrorString("decode can't handle " + v.Type().String())
}
typeLock.Lock();
engine := getDecEngine(rt);
typeLock.Unlock();
return engine.decode(r, v);
return engine.decodeStruct(r, uintptr(v.Addr()));
}