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indirection on array elements.

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R=rsc
DELTA=57  (34 added, 10 deleted, 13 changed)
OCL=31098
CL=31101
This commit is contained in:
Rob Pike 2009-07-02 17:21:48 -07:00
parent b5666a123a
commit c1fc4c8f37
3 changed files with 47 additions and 23 deletions
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44
src/pkg/gob/encode.go
View file

@ -14,6 +14,21 @@ import (
"unsafe";
)
// Step through the indirections on a type to discover the base type.
// Return the number of indirections.
func indirect(t reflect.Type) (rt reflect.Type, count int) {
rt = t;
for {
pt, ok := rt.(reflect.PtrType);
if !ok {
break
}
rt = pt.Sub();
count++;
}
return;
}
// 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
@ -280,13 +295,21 @@ func encodeStruct(engine *encEngine, w io.Writer, basep uintptr) os.Error {
return state.err
}
func encodeArray(w io.Writer, p uintptr, op encOp, elemWid int, length int) os.Error {
func encodeArray(w io.Writer, p uintptr, op encOp, elemWid int, length int, elemIndir int) os.Error {
state := new(EncState);
state.w = w;
state.fieldnum = -1;
EncodeUint(state, uint64(length));
for i := 0; i < length && state.err == nil; i++ {
op(nil, state, unsafe.Pointer(p)); // TODO(r): indir on elements
up := unsafe.Pointer(p);
if elemIndir > 0 {
if up = encIndirect(up, elemIndir); up == nil {
state.err = os.ErrorString("encodeArray: nil element");
break
}
p = uintptr(up);
}
op(nil, state, unsafe.Pointer(p));
p += uintptr(elemWid);
}
return state.err
@ -325,20 +348,22 @@ func encOpFor(typ reflect.Type) encOp {
case atyp.IsSlice():
// Slices have a header; we decode it to find the underlying array.
elemOp := encOpFor(atyp.Elem());
_, indir := indirect(atyp.Elem());
op = func(i *encInstr, state *EncState, p unsafe.Pointer) {
slice := *(*reflect.SliceHeader)(p);
if slice.Len == 0 {
return
}
state.update(i);
state.err = encodeArray(state.w, slice.Data, elemOp, atyp.Elem().Size(), int(slice.Len));
state.err = encodeArray(state.w, slice.Data, elemOp, atyp.Elem().Size(), int(slice.Len), indir);
};
case !atyp.IsSlice():
// True arrays have size in the type.
elemOp := encOpFor(atyp.Elem());
_, indir := indirect(atyp.Elem());
op = func(i *encInstr, state *EncState, p unsafe.Pointer) {
state.update(i);
state.err = encodeArray(state.w, uintptr(p), elemOp, atyp.Elem().Size(), atyp.Len());
state.err = encodeArray(state.w, uintptr(p), elemOp, atyp.Elem().Size(), atyp.Len(), indir);
};
}
}
@ -398,18 +423,13 @@ func getEncEngine(rt reflect.Type) *encEngine {
func Encode(w io.Writer, e interface{}) os.Error {
// Dereference down to the underlying object.
rt := reflect.Typeof(e);
rt, indir := indirect(reflect.Typeof(e));
v := reflect.NewValue(e);
for {
pt, ok := rt.(reflect.PtrType);
if !ok {
break
}
rt = pt.Sub();
for i := 0; i < indir; i++ {
v = reflect.Indirect(v);
}
if v.Kind() != reflect.StructKind {
return os.ErrorString("decode can't handle " + v.Type().String())
return os.ErrorString("encode can't handle " + v.Type().String())
}
typeLock.Lock();
engine := getEncEngine(rt);