Golang reflect.NewAt函数代码示例

// 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 == -1 {
		rt = reflect.PtrTo(rt)
	} else if ut.encIndir > 0 {
		for i := int8(0); i < ut.encIndir; i++ {
			rt = rt.Elem()
		}
	}
	var op encOp
	op = func(i *encInstr, state *encoderState, p unsafe.Pointer) {
		var v reflect.Value
		if ut.encIndir == -1 {
			// Need to climb up one level to turn value into pointer.
			v = reflect.NewAt(rt, unsafe.Pointer(&p)).Elem()
		} else {
			v = reflect.NewAt(rt, p).Elem()
		}
		if !state.sendZero && isZero(v) {
			return
		}
		state.update(i)
		state.enc.encodeGobEncoder(state.b, ut, v)
	}
	return &op, int(ut.encIndir) // encIndir: op will get called with p == address of receiver.
}

// gobDecodeOpFor returns the op for a type that is known to implement
// GobDecoder.
func (dec *Decoder) gobDecodeOpFor(ut *userTypeInfo) (*decOp, int) {
	rcvrType := ut.user
	if ut.decIndir == -1 {
		rcvrType = reflect.PtrTo(rcvrType)
	} else if ut.decIndir > 0 {
		for i := int8(0); i < ut.decIndir; i++ {
			rcvrType = rcvrType.Elem()
		}
	}
	var op decOp
	op = func(i *decInstr, state *decoderState, p unsafe.Pointer) {
		// Caller has gotten us to within one indirection of our value.
		if i.indir > 0 {
			if *(*unsafe.Pointer)(p) == nil {
				*(*unsafe.Pointer)(p) = unsafe.Pointer(reflect.New(ut.base).Pointer())
			}
		}
		// Now p is a pointer to the base type.  Do we need to climb out to
		// get to the receiver type?
		var v reflect.Value
		if ut.decIndir == -1 {
			v = reflect.NewAt(rcvrType, unsafe.Pointer(&p)).Elem()
		} else {
			v = reflect.NewAt(rcvrType, p).Elem()
		}
		state.dec.decodeGobDecoder(ut, state, v)
	}
	return &op, int(ut.indir)

}

func (func_data *FuncData) Call(args unsafe.Pointer, ret unsafe.Pointer) {

	numIn := func_data.fn.Type().NumIn()

	var goArgs []*uint32
	get_c_slice(args, numIn, unsafe.Pointer(&goArgs))

	getArg := func(index int) reflect.Value {
		return reflect.NewAt(func_data.fn_type.In(index), unsafe.Pointer(goArgs[index])).Elem()
	}

	funArgs := make([]reflect.Value, numIn)

	for i := 0; i < numIn; i++ {
		funArgs[i] = getArg(i)
	}

	rets := func_data.fn.Call(funArgs)

	numOut := func_data.fn_type.NumOut()

	if numOut == 1 {
		reflect.NewAt(func_data.fn_type.Out(0), ret).Elem().Set(rets[0])
	}
}

func valRepr(s *gosym.Sym, typ reflect.Type, values []string, _html bool) (r string) {
	val, _ := strconv.ParseUint(values[0], 0, 64)
	var val2 uint64
	if len(values) > 1 {
		val2, _ = strconv.ParseUint(values[1], 0, 64)
	}
	// If there's a panic prettyfy'ing the value just
	// assume it's a pointer. It's better than
	// omitting the error page.
	defer func() {
		if recover() != nil {
			r = pointerRepr(nil, val, false)
		}
	}()
	switch types.Kind(typ.Kind()) {
	case types.Bool:
		if val == 0 {
			return "= false"
		}
		return "= true"
	case types.Int:
		return "= " + strconv.FormatInt(int64(val), 10)
	case types.Uint:
		return "= " + strconv.FormatUint(val, 10)
	case types.Float:
		if typ.Kind() == reflect.Float32 {
			return "= " + strconv.FormatFloat(float64(math.Float32frombits(uint32(val))), 'g', -1, 32)
		}
		return "= " + strconv.FormatFloat(math.Float64frombits(uint64(val)), 'g', -1, 64)
	case types.Slice:
		return sliceRepr(val, val2, s)
	case types.String:
		v := stringRepr(val, val2)
		if _html {
			v = html.Escape(v)
		}
		return v
	case types.Interface:
		if typ.NumMethod() == 0 {
			return emptyInterfaceRepr(val, val2)
		}
		idata := [2]uintptr{uintptr(val), uintptr(val2)}
		v := reflect.NewAt(typ, unsafe.Pointer(&idata[0])).Elem()
		return descRepr(val, &v, _html)
	case types.Func:
		fn := reflect.NewAt(typ, unsafe.Pointer(&val)).Elem()
		f := runtime.FuncForPC(fn.Pointer())
		if f != nil {
			return "= " + f.Name()
		}
	}
	return pointerRepr(typ, val, _html)
}

func (c *RedisCacher) deserialize(byt []byte) (ptr interface{}, err error) {
	b := bytes.NewBuffer(byt)
	decoder := gob.NewDecoder(b)

	var p interface{}
	err = decoder.Decode(&p)
	if err != nil {
		c.logErrf("decode failed: %v", err)
		return
	}

	v := reflect.ValueOf(p)
	c.logDebugf("deserialize type:%v", v.Type())
	if v.Kind() == reflect.Struct {

		var pp interface{} = &p
		datas := reflect.ValueOf(pp).Elem().InterfaceData()

		sp := reflect.NewAt(v.Type(),
			unsafe.Pointer(datas[1])).Interface()
		ptr = sp
		vv := reflect.ValueOf(ptr)
		c.logDebugf("deserialize convert ptr type:%v | CanAddr:%t", vv.Type(), vv.CanAddr())
	} else {
		ptr = p
	}
	return
}

//export goMInit
func goMInit(db, pClientData unsafe.Pointer, argc int, argv **C.char, pzErr **C.char, isCreate int) unsafe.Pointer {
	m := (*sqliteModule)(pClientData)
	if m.c.db != (*C.sqlite3)(db) {
		*pzErr = mPrintf("%s", "Inconsistent db handles")
		return nil
	}
	args := make([]string, argc)
	var A []*C.char
	slice := reflect.SliceHeader{Data: uintptr(unsafe.Pointer(argv)), Len: argc, Cap: argc}
	a := reflect.NewAt(reflect.TypeOf(A), unsafe.Pointer(&slice)).Elem().Interface()
	for i, s := range a.([]*C.char) {
		args[i] = C.GoString(s)
	}
	var vTab VTab
	var err error
	if isCreate == 1 {
		vTab, err = m.module.Create(m.c, args)
	} else {
		vTab, err = m.module.Connect(m.c, args)
	}

	if err != nil {
		*pzErr = mPrintf("%s", err.Error())
		return nil
	}
	vt := &sqliteVTab{m, vTab, nil}
	// prevents 'vt' from being gced
	if m.vts == nil {
		m.vts = make(map[*sqliteVTab]bool)
	}
	m.vts[vt] = true
	*pzErr = nil
	return unsafe.Pointer(vt)
}

func (m *GslMultiset) Slice_() interface{} {
	baseType := gogsl.GOGSL_SIZE_T_TYPE
	sliceType := reflect.SliceOf(baseType)
	size := K(m)
	hdr := &reflect.SliceHeader{Len: size, Cap: size, Data: uintptr(C.get_multiset_data((*C.gsl_multiset)(unsafe.Pointer(m.Ptr()))))}
	return reflect.NewAt(sliceType, unsafe.Pointer(hdr)).Elem().Interface()
}

//export closureMarshal
func closureMarshal(closure *C.GClosure, ret *C.GValue, nParams C.guint, params *C.GValue, hint, data C.gpointer) {
	// callback value
	f := *((*interface{})(unsafe.Pointer(data)))
	fValue := reflect.ValueOf(f)
	fType := fValue.Type()
	if int(nParams) != fType.NumIn() {
		log.Fatal("number of parameters and arguments mismatch")
	}

	// convert GValue to reflect.Value
	var paramSlice []C.GValue
	h := (*reflect.SliceHeader)(unsafe.Pointer(&paramSlice))
	h.Len = int(nParams)
	h.Cap = h.Len
	h.Data = uintptr(unsafe.Pointer(params))
	var arguments []reflect.Value
	for i, gv := range paramSlice {
		goValue := fromGValue(&gv)
		var arg reflect.Value
		switch fType.In(i).Kind() {
		case reflect.Ptr:
			p := goValue.(unsafe.Pointer)
			arg = reflect.NewAt(fType.In(i), unsafe.Pointer(&p)).Elem()
		default:
			panic("FIXME") //TODO
		}
		arguments = append(arguments, arg)
	}

	// call
	fValue.Call(arguments[:fType.NumIn()])

	//TODO set return value
}

func sliceEncoder(typ reflect.Type) (typeEncoder, error) {
	switch typ.Elem().Kind() {
	case reflect.Int8, reflect.Uint8, reflect.Int16, reflect.Uint16, reflect.Int32, reflect.Uint32, reflect.Int64, reflect.Uint64:
		// Take advantage of the fast path in Write
		return func(enc *encoder, p unsafe.Pointer) error {
			v := reflect.NewAt(typ, p).Elem()
			return Write(enc, enc.order, v.Interface())
		}, nil
	}
	etyp := typ.Elem()
	eenc, err := makeEncoder(etyp)
	if err != nil {
		return nil, err
	}
	s := etyp.Size()
	return func(enc *encoder, p unsafe.Pointer) error {
		h := (*reflect.SliceHeader)(p)
		ep := unsafe.Pointer(h.Data)
		for ii := 0; ii < h.Len; ii++ {
			if err := eenc(enc, ep); err != nil {
				return err
			}
		}
		ep = unsafe.Pointer(uintptr(ep) + s)
		return nil
	}, nil
}

func (g *Group) scanSubGroupHandler(realval reflect.Value, sfield *reflect.StructField) (bool, error) {
	mtag := newMultiTag(string(sfield.Tag))

	if err := mtag.Parse(); err != nil {
		return true, err
	}

	subgroup := mtag.Get("group")

	if len(subgroup) != 0 {
		ptrval := reflect.NewAt(realval.Type(), unsafe.Pointer(realval.UnsafeAddr()))
		description := mtag.Get("description")

		group, err := g.AddGroup(subgroup, description, ptrval.Interface())
		if err != nil {
			return true, err
		}

		group.Namespace = mtag.Get("namespace")
		group.Hidden = mtag.Get("hidden") != ""

		return true, nil
	}

	return false, nil
}

func (c *Command) scanSubCommandHandler(parentg *Group) scanHandler {
	f := func(realval reflect.Value, sfield *reflect.StructField) (bool, error) {
		mtag := newMultiTag(string(sfield.Tag))

		if err := mtag.Parse(); err != nil {
			return true, err
		}

		subcommand := mtag.Get("command")

		if len(subcommand) != 0 {
			ptrval := reflect.NewAt(realval.Type(), unsafe.Pointer(realval.UnsafeAddr()))

			shortDescription := mtag.Get("description")
			longDescription := mtag.Get("long-description")
			subcommandsOptional := mtag.Get("subcommands-optional")

			subc, err := c.AddCommand(subcommand, shortDescription, longDescription, ptrval.Interface())

			if err != nil {
				return true, err
			}

			if len(subcommandsOptional) > 0 {
				subc.SubcommandsOptional = true
			}

			return true, nil
		}

		return parentg.scanSubGroupHandler(realval, sfield)
	}

	return f
}

// Decode an embedded message.
func (o *Buffer) dec_struct_message(p *Properties, base uintptr) (err error) {
	raw, e := o.DecodeRawBytes(false)
	if e != nil {
		return e
	}

	ptr := (**struct{})(unsafe.Pointer(base + p.offset))
	typ := p.stype.Elem()
	bas := reflect.New(typ).Pointer()
	structp := unsafe.Pointer(bas)
	*ptr = (*struct{})(structp)

	// If the object can unmarshal itself, let it.
	if p.isMarshaler {
		iv := reflect.NewAt(p.stype.Elem(), structp).Interface()
		return iv.(Unmarshaler).Unmarshal(raw)
	}

	obuf := o.buf
	oi := o.index
	o.buf = raw
	o.index = 0

	err = o.unmarshalType(p.stype, p.sprop, false, bas)
	o.buf = obuf
	o.index = oi

	return err
}

//export gslNtupleValueFunctionCaller
func gslNtupleValueFunctionCaller(x uintptr, cFunParamPtr uintptr) float64 {
	ntsf := (*GslNtupleValueFunction)(unsafe.Pointer(cFunParamPtr))
	hdr := &reflect.SliceHeader{Data: x, Len: ntsf.ntuple.refLen, Cap: ntsf.ntuple.refLen}
	sliceType := reflect.SliceOf(ntsf.ntuple.baseType)
	slice := reflect.NewAt(sliceType, unsafe.Pointer(hdr)).Elem().Interface()
	return ntsf.Function(slice, ntsf.Params)
}

//export gslSimanCopyConstructorCaller
func gslSimanCopyConstructorCaller(xptr uintptr) uintptr {
	//fmt.Println("CC")
	xarg := (*GslSimanArgument)(unsafe.Pointer(xptr))
	if xarg.impl.ctorFn != nil {
		nptr := xarg.impl.ctorFn(xarg.x)
		rv := &GslSimanArgument{impl: xarg.impl, x: nptr}
		rvptr := uintptr(unsafe.Pointer(rv))
		xarg.impl.holdRefs[rvptr] = rv
		//fmt.Printf("CC. RV x is %s inval=%f, outval=%f\n", reflect.TypeOf(rv.x).String(), *xarg.x.(*float64), *rv.x.(*float64))
		return rvptr
	} else {
		var rv *GslSimanArgument
		x := reflect.ValueOf(xarg.x)
		xType := x.Type()
		baseType := xType.Elem()
		if xType.Kind() == reflect.Ptr {
			nxptr := reflect.New(baseType)
			//C.memcpy(unsafe.Pointer(nxptr), unsafe.Pointer(x.Pointer()), C.size_t(baseType.Size()))
			nxptr.Elem().Set(x.Elem())
			rv = &GslSimanArgument{impl: xarg.impl, x: reflect.NewAt(baseType, unsafe.Pointer(nxptr.Pointer())).Interface()}
		} else {
			panic("fail")
			rv = &GslSimanArgument{impl: xarg.impl, x: xarg.x}
		}
		//fmt.Printf("CC RV x is %s inval=%f, outval=%f\n", reflect.TypeOf(rv.x).String(), *xarg.x.(*float64), *rv.x.(*float64))
		rvptr := uintptr(unsafe.Pointer(rv))
		xarg.impl.holdRefs[rvptr] = rv
		return rvptr
	}
}

// UnsafeReflectValue converts the passed reflect.Value into a one that bypasses
// the typical safety restrictions preventing access to unaddressable and
// unexported data.  It works by digging the raw pointer to the underlying
// value out of the protected value and generating a new unprotected (unsafe)
// reflect.Value to it.
//
// This allows us to check for implementations of the Stringer and error
// interfaces to be used for pretty printing ordinarily unaddressable and
// inaccessible values such as unexported struct fields.
func UnsafeReflectValue(v reflect.Value) (rv reflect.Value) {
	indirects := 1
	vt := v.Type()
	upv := unsafe.Pointer(uintptr(unsafe.Pointer(&v)) + offsetPtr)
	rvf := *(*uintptr)(unsafe.Pointer(uintptr(unsafe.Pointer(&v)) + offsetFlag))
	if rvf&flagIndir != 0 {
		vt = reflect.PtrTo(v.Type())
		indirects++
	} else if offsetScalar != 0 {
		// The value is in the scalar field when it's not one of the
		// reference types.
		switch vt.Kind() {
		case reflect.Uintptr:
		case reflect.Chan:
		case reflect.Func:
		case reflect.Map:
		case reflect.Ptr:
		case reflect.UnsafePointer:
		default:
			upv = unsafe.Pointer(uintptr(unsafe.Pointer(&v)) +
				offsetScalar)
		}
	}

	pv := reflect.NewAt(vt, upv)
	rv = pv
	for i := 0; i < indirects; i++ {
		rv = rv.Elem()
	}
	return rv
}