【发布时间】：2013-01-01 22:34:18
【问题描述】：
我正在开发一个在线预订网站（航空公司），我想根据某些设置验证用户/客户选择的路线是否有效。现有代码使用了很多枚举，我发现自己做了很多 if/if else/else 来将特定枚举映射到我想要发生的特定操作。 What I want to do is to write a enum-specific method that would do the mapping for me. Is there any standard way to do this?
这是一个简化版本的应用代码，使用与真实应用相同的类名/枚举值等：
// real app has 9 members, shortened for simplicity's sake
public enum RegionType
{
Station,
Country,
All
}
public enum Directionality
{
Between,
From,
To
}
// simplified version
public class Flight
{
public RegionType RegionType { get; set; }
public RegionType TravelRegionType { get; set; }
public string RegionCode { get; set; }
public string TravelRegionCode { get; set; }
public string RegionCountryCode { get; set; }
public string TravelRegionCountryCode { get; set; }
public Directionality Directionality { get; set; }
}
以下是一些示例用法：
// valid flight
Flight flight = new Flight()
{
RegionCode = "NY",
CountryCode = "JP",
RegionType = RegionType.Station,
TravelRegionType = RegionType.Country,
Directionality = Directionality.Between
};
// these are the station code/country code that user selected
// needs to be validated against the Flight object above
var userSelectedRoutes = new List<KeyValuePair<string, string>>()
{
new KeyValuePair<string, string>("NY", "JP"),
new KeyValuePair<string, string>("NY", "AU"),
new KeyValuePair<string, string>("JP", "NY")
};
我写了一些代码验证来减少嵌套的 if/else if/else 枚举匹配：
private bool IsRouteValid(Directionality direction, string origin,
string destination, string departure, string arrival)
{
// both departure station and arrival station
if (direction == Directionality.Between)
{
return (origin.Equals(departure, StringComparison.OrdinalIgnoreCase)
&& destination.Equals(arrival, StringComparison.OrdinalIgnoreCase)
|| origin.Equals(arrival, StringComparison.OrdinalIgnoreCase)
&& destination.Equals(departure, StringComparison.OrdinalIgnoreCase));
}
else if (direction == Directionality.From)
{
return (origin.Equals(departure,
StringComparison.OrdinalIgnoreCase));
}
else if (direction == Directionality.To)
{
return (destination.Equals(arrival,
StringComparison.OrdinalIgnoreCase));
}
return false;
}
这是我要更改的杂乱代码：
if (flight.RegionType == RegionType.Station
&& flight.TravelRegionType == RegionType.Country)
{
return userSelectedRoutes.Any(route =>
IsRouteValid(flight.Directionality, route.Key, route.Value,
flight.RegionCode, flight.TravelRegionCode));
}
else if (flight.RegionType == RegionType.Country
&& flight.TravelRegionType == RegionType.Station)
{
return userSelectedRoutes.Any(route =>
IsRouteValid(flight.Directionality, route.Key, route.Value,
flight.CountryCode, flight.RegionCode));
}
else if (flight.RegionType == RegionType.Station
&& flight.TravelRegionType == RegionType.Station)
{
return userSelectedRoutes.Any(route =>
IsRouteValid(flight.Directionality, route.Key, route.Value,
flight.RegionCode, flight.TravelRegionCode));
}
else if (flight.RegionType == RegionType.Station
&& flight.TravelRegionType == RegionType.All)
{
return userSelectedRoutes.Any(route =>
IsRouteValid(flight.Directionality, route.Key, route.Value,
flight.RegionCode, route.Value));
}
else if (flight.RegionType == RegionType.All
&& flight.TravelRegionType == RegionType.Station)
{
return userSelectedRoutes.Any(route =>
IsRouteValid(flight.Directionality, route.Key, route.Value,
route.Key, flight.TravelRegionCode));
}
else if (flight.RegionType == RegionType.All
&& flight.TravelRegionType == RegionType.All)
{
return true;
}
else
{
return false;
}
传奇：
RegionCode = 出发站/始发站 TravelRegionCode = 到达站/目的地 Between = 路线只能从给定的出发站和到达站出发，反之亦然（前 NY-JP或 JP-NY）From = 从特定车站到任何路线（例如 AU-All）To = 到特定车站的任何路线（例如 All -AU)
如果您注意到，上述所有条件的.Any 相同，略有变化。如果可能的话，我想减少代码冗余。我使用了KeyValuePair，所以我在一个数据类型上同时拥有出发站和到达站。
关于如何使这段代码不那么凌乱/美观的任何想法？我知道我也对IsRouteValid() 进行了硬编码，但我100% 确定Directionality 只能有3 种可能的组合。另一方面，RegionType 可以有几种组合，例如 Station-Station、Station-Country、Country-Station、Country-Country 等。
预期输出：
第一条路线的有效/真（NY-JP）
第二条路线无效/错误 (NY-AU)
第三条路线（JP-NY）的有效/真[因为Directionality是Between]
感谢您阅读这个很长的查询，并提前感谢您的反馈和建议。
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