Golang Type.NumOut方法代码示例

func typeString_FuncOrMethod(
	name string,
	t reflect.Type,
	pkgPath string) (s string) {
	// Deal with input types.
	var in []string
	for i := 0; i < t.NumIn(); i++ {
		in = append(in, typeString(t.In(i), pkgPath))
	}

	// And output types.
	var out []string
	for i := 0; i < t.NumOut(); i++ {
		out = append(out, typeString(t.Out(i), pkgPath))
	}

	// Put it all together.
	s = fmt.Sprintf(
		"%s(%s) (%s)",
		name,
		strings.Join(in, ", "),
		strings.Join(out, ", "))

	return
}

func OutTypes(fnType reflect.Type) []reflect.Type {
	var types []reflect.Type
	for i := 0; i < fnType.NumOut(); i++ {
		types = append(types, fnType.Out(i))
	}
	return types
}

// Note: Methods take the receiver as the first argument, which the want
// signature doesn't include.
func sigMatches(got, want reflect.Type) bool {

	nin := want.NumIn()
	if got.NumIn()-1 != nin {
		return false
	}

	nout := want.NumOut()
	if got.NumOut() != nout {
		return false
	}

	for i := 0; i < nin; i++ {
		if got.In(i+1) != want.In(i) {
			return false
		}
	}

	for i := 0; i < nout; i++ {
		if got.Out(i) != want.Out(i) {
			return false
		}
	}
	return true
}

// Add all necessary imports for the type, recursing as appropriate.
func addImportsForType(imports importMap, t reflect.Type) {
	// Add any import needed for the type itself.
	addImportForType(imports, t)

	// Handle special cases where recursion is needed.
	switch t.Kind() {
	case reflect.Array, reflect.Chan, reflect.Ptr, reflect.Slice:
		addImportsForType(imports, t.Elem())

	case reflect.Func:
		// Input parameters.
		for i := 0; i < t.NumIn(); i++ {
			addImportsForType(imports, t.In(i))
		}

		// Return values.
		for i := 0; i < t.NumOut(); i++ {
			addImportsForType(imports, t.Out(i))
		}

	case reflect.Map:
		addImportsForType(imports, t.Key())
		addImportsForType(imports, t.Elem())
	}
}

// Verifies whether a conversion function has a correct signature.
func verifyConversionFunctionSignature(ft reflect.Type) error {
	if ft.Kind() != reflect.Func {
		return fmt.Errorf("expected func, got: %v", ft)
	}
	if ft.NumIn() != 3 {
		return fmt.Errorf("expected three 'in' params, got: %v", ft)
	}
	if ft.NumOut() != 1 {
		return fmt.Errorf("expected one 'out' param, got: %v", ft)
	}
	if ft.In(0).Kind() != reflect.Ptr {
		return fmt.Errorf("expected pointer arg for 'in' param 0, got: %v", ft)
	}
	if ft.In(1).Kind() != reflect.Ptr {
		return fmt.Errorf("expected pointer arg for 'in' param 1, got: %v", ft)
	}
	scopeType := Scope(nil)
	if e, a := reflect.TypeOf(&scopeType).Elem(), ft.In(2); e != a {
		return fmt.Errorf("expected '%v' arg for 'in' param 2, got '%v' (%v)", e, a, ft)
	}
	var forErrorType error
	// This convolution is necessary, otherwise TypeOf picks up on the fact
	// that forErrorType is nil.
	errorType := reflect.TypeOf(&forErrorType).Elem()
	if ft.Out(0) != errorType {
		return fmt.Errorf("expected error return, got: %v", ft)
	}
	return nil
}

func newTypeFromFactoryFunction(function interface{}, factoryType reflect.Type, parameters []interface{}) TypeFactory {
	if factoryType.NumOut() != 1 {
		return newInvalidType(fmt.Errorf("invalid number of return parameters: %d", factoryType.NumOut()))
	}

	kindOfGeneratedType := factoryType.Out(0).Kind()
	if kindOfGeneratedType != reflect.Interface && kindOfGeneratedType != reflect.Ptr {
		return newInvalidType(fmt.Errorf("return parameter is no interface or pointer but a %v", kindOfGeneratedType))
	}

	if factoryType.IsVariadic() {
		if factoryType.NumIn() > len(parameters) {
			return newInvalidType(fmt.Errorf("invalid number of input parameters for variadic function: got %d but expected at least %d", len(parameters), factoryType.NumIn()))
		}
	} else {
		if factoryType.NumIn() != len(parameters) {
			return newInvalidType(fmt.Errorf("invalid number of input parameters: got %d but expected %d", len(parameters), factoryType.NumIn()))
		}
	}

	t := &typeFactory{
		factory:     reflect.ValueOf(function),
		factoryType: factoryType,
	}

	var err error
	t.factoryArguments, err = buildFactoryCallArguments(factoryType, parameters)
	if err != nil {
		return newInvalidType(err)
	}

	return t
}

// verifyHandler ensures that the given t is a function with the following signature:
// func(json.Context, *ArgType)(*ResType, error)
func verifyHandler(t reflect.Type) error {
	if t.NumIn() != 2 || t.NumOut() != 2 {
		return fmt.Errorf("handler should be of format func(json.Context, *ArgType) (*ResType, error)")
	}

	isStructPtr := func(t reflect.Type) bool {
		return t.Kind() == reflect.Ptr && t.Elem().Kind() == reflect.Struct
	}
	isMap := func(t reflect.Type) bool {
		return t.Kind() == reflect.Map && t.Key().Kind() == reflect.String
	}
	validateArgRes := func(t reflect.Type, name string) error {
		if !isStructPtr(t) && !isMap(t) {
			return fmt.Errorf("%v should be a pointer to a struct, or a map[string]interface{}", name)
		}
		return nil
	}

	if t.In(0) != typeOfContext {
		return fmt.Errorf("arg0 should be of type json.Context")
	}
	if err := validateArgRes(t.In(1), "second argument"); err != nil {
		return err
	}
	if err := validateArgRes(t.Out(0), "first return value"); err != nil {
		return err
	}
	if !t.Out(1).AssignableTo(typeOfError) {
		return fmt.Errorf("second return value should be an error")
	}

	return nil
}

func checkFunc(fnType reflect.Type) (bool, error) {
	var state State
	foundState := 0
	nin := fnType.NumIn()
	for i := 0; i < nin; i++ {
		if fnType.In(i) == reflect.TypeOf(state) {
			foundState++
		} else if fnType.In(i) == reflect.TypeOf(&state) {
			return false, fmt.Errorf("raw function can not use `*State' as arg, instead using `State'")
		}
	}

	wrongRawFunc := false
	if foundState > 1 {
		wrongRawFunc = true
	} else if foundState == 1 {
		nout := fnType.NumOut()
		if nin != 1 || nout != 1 {
			wrongRawFunc = true
		} else {
			if fnType.Out(0).Kind() != reflect.Int {
				wrongRawFunc = true
			}
		}
	}

	if wrongRawFunc {
		return false, fmt.Errorf("raw function must be type: `func(State) int'")
	}

	return true, nil
}

func makeClosure(fv reflect.Value, ft reflect.Type) *function {
	fn := &function{
		call: fv,
	}

	var rt = Void
	var at []Type

	if n := ft.NumOut(); n != 0 {
		rt = makeRetType(reflect.New(ft.Out(0)))
	}

	if n := ft.NumIn(); n != 0 {
		at = make([]Type, n)

		for i := 0; i != n; i++ {
			at[i] = makeArgType(reflect.Zero(ft.In(i)))
		}
	}

	fn.Interface = Prepare(rt, at...)

	if err := constructClosure(fn); err != nil {
		panic(err)
	}

	runtime.SetFinalizer(fn, destroyClosure)
	return fn
}

func methSigMatches(got reflect.Type, _want interface{}) error {
	// Note: Methods take the receiver as the first argument, which the want
	// signature doesn't include.

	if got.NumIn() == 0 {
		// The receiver is missing!
		return fmt.Errorf("Method without reciever!")
	}

	want := reflect.TypeOf(_want)

	if got.NumIn()-1 != want.NumIn() {
		return fmt.Errorf("Method should have %d arguments, not %d", want.NumIn(), got.NumIn()-1)
	}

	if got.NumOut() != want.NumOut() {
		return fmt.Errorf("Method should have %d return values, not %d", want.NumOut(), got.NumOut())
	}

	for i := 0; i < want.NumIn(); i++ {
		if got.In(i+1) != want.In(i) {
			return fmt.Errorf("Method argument %d should be %v, not %v", i+1, want.In(i), got.In(i+1))
		}
	}

	for i := 0; i < want.NumOut(); i++ {
		if got.Out(i) != want.Out(i) {
			return fmt.Errorf("Method return value %d should be %v, not %v", i+1, want.Out(i), got.Out(i))
		}
	}

	return nil
}

func FormatFuncArguments(t reflect.Type) (decl string) {
	decl = "("
	in := make([]string, t.NumIn())

	for i := range in {
		in[i] = ValType(t.In(i))
	}

	decl += strings.Join(in, ",") + ")"

	out := make([]string, t.NumOut())
	if len(out) > 0 {

		for i := range out {
			out[i] = ValType(t.Out(i))
		}

		s := strings.Join(out, ",")

		if len(out) != 1 {
			s = "(" + s + ")"
		}

		decl += " " + s
	}
	return
}

func hasLastError(t reflect.Type) bool {
	N := t.NumOut()
	if N == 0 {
		return false
	}
	return t.Out(N-1) == errorType
}

// Verifies whether a deep-copy function has a correct signature.
func verifyDeepCopyFunctionSignature(ft reflect.Type) error {
	if ft.Kind() != reflect.Func {
		return fmt.Errorf("expected func, got: %v", ft)
	}
	if ft.NumIn() != 3 {
		return fmt.Errorf("expected three 'in' params, got $v", ft)
	}
	if ft.NumOut() != 1 {
		return fmt.Errorf("expected one 'out' param, got %v", ft)
	}
	if ft.In(1).Kind() != reflect.Ptr {
		return fmt.Errorf("expected pointer arg for 'in' param 1, got: %v", ft)
	}
	if ft.In(1).Elem() != ft.In(0) {
		return fmt.Errorf("expected 'in' param 0 the same as param 1, got: %v", ft)
	}
	var forClonerType Cloner
	if expected := reflect.TypeOf(&forClonerType); ft.In(2) != expected {
		return fmt.Errorf("expected '%v' arg for 'in' param 2, got: '%v'", expected, ft.In(2))
	}
	var forErrorType error
	// This convolution is necessary, otherwise TypeOf picks up on the fact
	// that forErrorType is nil
	errorType := reflect.TypeOf(&forErrorType).Elem()
	if ft.Out(0) != errorType {
		return fmt.Errorf("expected error return, got: %v", ft)
	}
	return nil
}

func (ms *GobMarshaller) Prepare(name string, fn interface{}) (err error) {
	var (
		fT reflect.Type
	)
	// Gob needs to register type before encode/decode
	if fT = reflect.TypeOf(fn); fT.Kind() != reflect.Func {
		err = fmt.Errorf("fn is not a function but %v", fn)
		return
	}

	reg := func(v reflect.Value) (err error) {
		if !v.CanInterface() {
			err = fmt.Errorf("Can't convert to value in input of %v for name:%v", fn, name)
			return
		}

		gob.Register(v.Interface())
		return
	}

	for i := 0; i < fT.NumIn(); i++ {
		// create a zero value of the type of parameters
		if err = reg(reflect.Zero(fT.In(i))); err != nil {
			return
		}
	}

	for i := 0; i < fT.NumOut(); i++ {
		if err = reg(reflect.Zero(fT.Out(i))); err != nil {
			return
		}
	}

	return
}

func returns(f reflect.Type) []reflect.Type {
	out := make([]reflect.Type, f.NumOut())
	for i := 0; i < f.NumOut(); i++ {
		out[i] = f.Out(i)
	}
	return out
}