func typeFromType()

in mockgen/model/model.go [372:465]
83 lines of code
21 McCabe index (conditional complexity)

func typeFromType(t reflect.Type) (Type, error) {
	// Hack workaround for https://golang.org/issue/3853.
	// This explicit check should not be necessary.
	if t == byteType {
		return PredeclaredType("byte"), nil
	}

	if imp := t.PkgPath(); imp != "" {
		return &NamedType{
			Package: impPath(imp),
			Type:    t.Name(),
		}, nil
	}

	// only unnamed or predeclared types after here

	// Lots of types have element types. Let's do the parsing and error checking for all of them.
	var elemType Type
	switch t.Kind() {
	case reflect.Array, reflect.Chan, reflect.Map, reflect.Ptr, reflect.Slice:
		var err error
		elemType, err = typeFromType(t.Elem())
		if err != nil {
			return nil, err
		}
	}

	switch t.Kind() {
	case reflect.Array:
		return &ArrayType{
			Len:  t.Len(),
			Type: elemType,
		}, nil
	case reflect.Bool, reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
		reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr,
		reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128, reflect.String:
		return PredeclaredType(t.Kind().String()), nil
	case reflect.Chan:
		var dir ChanDir
		switch t.ChanDir() {
		case reflect.RecvDir:
			dir = RecvDir
		case reflect.SendDir:
			dir = SendDir
		}
		return &ChanType{
			Dir:  dir,
			Type: elemType,
		}, nil
	case reflect.Func:
		in, variadic, out, err := funcArgsFromType(t)
		if err != nil {
			return nil, err
		}
		return &FuncType{
			In:       in,
			Out:      out,
			Variadic: variadic,
		}, nil
	case reflect.Interface:
		// Two special interfaces.
		if t.NumMethod() == 0 {
			return PredeclaredType("interface{}"), nil
		}
		if t == errorType {
			return PredeclaredType("error"), nil
		}
	case reflect.Map:
		kt, err := typeFromType(t.Key())
		if err != nil {
			return nil, err
		}
		return &MapType{
			Key:   kt,
			Value: elemType,
		}, nil
	case reflect.Ptr:
		return &PointerType{
			Type: elemType,
		}, nil
	case reflect.Slice:
		return &ArrayType{
			Len:  -1,
			Type: elemType,
		}, nil
	case reflect.Struct:
		if t.NumField() == 0 {
			return PredeclaredType("struct{}"), nil
		}
	}

	// TODO: Struct, UnsafePointer
	return nil, fmt.Errorf("can't yet turn %v (%v) into a model.Type", t, t.Kind())
}