Function MapDirect

mapper_func.go:74–119

============ 函数式泛型 Mapper (优化版) ============ MapDirect 同构/异构映射，直接返回结果 使用示例: dto := mapper.MapDirect[User, UserDTO](user)

(from From)

// MapDirect 同构/异构映射，直接返回结果
// 使用示例: dto := mapper.MapDirect[User, UserDTO](user)
func MapDirect[From, To any](from From) To {
	var result To
	
	fromVal := reflect.ValueOf(from)
	if !fromVal.IsValid() {
		return result
	}

	// 处理指针类型
	if fromVal.Kind() == reflect.Ptr {
		if fromVal.IsNil() {
			return result
		}
		fromVal = fromVal.Elem()
	}

	// 获取类型信息
	fromType := fromVal.Type()
	toType := reflect.TypeOf(result)
	
	if toType.Kind() != reflect.Struct {
		return result
	}

	// 尝试从缓存获取映射关系
	mappings, ok := getFieldMappings(fromType, toType)
	if !ok {
		mappings = buildFieldMappings(fromType, toType)
	}

	// 创建目标值
	toVal := reflect.New(toType).Elem()

	// 执行映射
	for _, m := range mappings {
		if len(m.fromIndex) > 0 {
			fromFieldVal := fromVal.FieldByIndex(m.fromIndex)
			toFieldVal := toVal.Field(m.toIndex)
			if toFieldVal.CanSet() {
				toFieldVal.Set(fromFieldVal)
			}
		}
	}
	
	return toVal.Interface().(To)
}

// MapDirectPtr 指针版本
// 使用示例: dto := mapper.MapDirectPtr[User, UserDTO](&user)