语境
我在内存中有一个有序（按名称）城市对象的列表，我需要在输入字符时获取这些城市的列表，有点像建议框。
例如：
如果列表中有马德里和马赛城市名称等，当我按下“M”字符时，我需要在返回的列表中获得马德里和马赛。好吧，在几年前，我会运行几个线程，以使事情进展得更快，但现在，使用 LINQ 和 TPL，经过几次测试，我得出的结论是，更快的方法是使用这些新库而不是手动操作。因此，我编写了一些脚本并相互测试了它们。每个被剪断的代码都在自己的类中运行：
//Snippet 1
List<ICity> objCities = new List<ICity>();
foreach (ICity objCity in this.m_objCities)
{
if (objCity.Name.Length >= pName.Length)
{
if (objCity.Name.Substring(0, pName.Length).Equals(pName))
{
objCities.Add(objCity);
}
}
else if (objCitys.Count > 0)
{
break;
}
}
return objCities;
//片段2
ICollection<ICity> objCities = base.m_objCities.Where((ICity pCity) =>
{
bool bFound = false;
if (pCity.Name.Length >= pName.Length)
{
bFound = pCity.Name.Substring(0, pName.Length).Equals(pName);
}
return bFound;
}).ToList();
return objCities;
//片段3
ICollection<ICity> objCities = base.m_objCities.AsParallel().Where((ICity pCity) =>
{
bool bFound = false;
if (pCity.Name.Length >= pName.Length)
{
bFound = pCity.Name.Substring(0, pName.Length).Equals(pName);
}
return bFound;
}).ToList();
return objCities;
//片段4
//Used as a class member
private List<ICollection<IStation>> objLastCities = new List<ICollection<IStation>>();
int iNameCount = pName.Length;
ICollection<ICity> objCities = null;
if (this.m_iLastNameCount == 0 || iNameCount == 1)
{
objCities = base.m_objCities.Where((ICity pCity) =>
{
bool bFound = false;
if (pCity.Name.Length >= pName.Length)
{
bFound = pCity.Name.Substring(0, pName.Length).Equals(pName);
}
return bFound;
}).ToList();
this.objLastCities.Clear();
this.objLastCities.Add(objCities);
this.m_iLastNameCount = 1;
}
else
{
if (iNameCount > this.m_iLastNameCount)
{
objCities = this.objLastCities[this.m_iLastNameCount - 1].Where((ICity pCity) =>
{
bool bFound = false;
if (pCity.Name.Length >= pName.Length)
{
bFound = pCity.Name.Substring(0, pName.Length).Equals(pName);
}
return bFound;
}).ToList();
this.objLastCities.Add(objCities);
this.m_iLastNameCount++;
}
else
{
objCities = base.m_objCities.Where((ICity pCity) =>
{
bool bFound = false;
if (pCity.Name.Length >= pName.Length)
{
bFound = pCity.Name.Substring(0, pName.Length).Equals(pName);
}
return bFound;
}).ToList();
this.objLastCities.RemoveAt(iNameCount - 1);
objCities = this.objLastCities[iNameCount - 1];
this.m_iLastNameCount--;
}
this.objLastCities.Add(objCities);
}
return this.objLastCities[this.objLastCities.Count - 1];
//片段5
////Member objects
private List<ICollection<ICity>> objLastCities = new List<ICollection<ICity>>();
private int m_iLastNameCount = 0;
private Dictionary<char, ICollection<ICity>> m_objCitiesByKey = null;
////Code that runs in the class contructor
this.m_objCitiesByKey.Add('A', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'A'; }).ToList());
this.m_objCitiesByKey.Add('B', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'B'; }).ToList());
this.m_objCitiesByKey.Add('C', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'C'; }).ToList());
this.m_objCitiesByKey.Add('D', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'D'; }).ToList());
this.m_objCitiesByKey.Add('E', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'E'; }).ToList());
this.m_objCitiesByKey.Add('F', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'F'; }).ToList());
this.m_objCitiesByKey.Add('G', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'G'; }).ToList());
this.m_objCitiesByKey.Add('H', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'H'; }).ToList());
this.m_objCitiesByKey.Add('I', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'I'; }).ToList());
this.m_objCitiesByKey.Add('J', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'J'; }).ToList());
this.m_objCitiesByKey.Add('K', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'K'; }).ToList());
this.m_objCitiesByKey.Add('L', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'L'; }).ToList());
this.m_objCitiesByKey.Add('M', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'M'; }).ToList());
this.m_objCitiesByKey.Add('N', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'N'; }).ToList());
this.m_objCitiesByKey.Add('O', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'O'; }).ToList());
this.m_objCitiesByKey.Add('P', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'P'; }).ToList());
this.m_objCitiesByKey.Add('Q', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'Q'; }).ToList());
this.m_objCitiesByKey.Add('R', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'R'; }).ToList());
this.m_objCitiesByKey.Add('S', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'S'; }).ToList());
this.m_objCitiesByKey.Add('T', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'T'; }).ToList());
this.m_objCitiesByKey.Add('U', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'U'; }).ToList());
this.m_objCitiesByKey.Add('V', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'V'; }).ToList());
this.m_objCitiesByKey.Add('W', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'W'; }).ToList());
this.m_objCitiesByKey.Add('X', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'X'; }).ToList());
this.m_objCitiesByKey.Add('Y', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'Y'; }).ToList());
this.m_objCitiesByKey.Add('Z', base.m_objCities.Where((ICity pCity) => { return pCity.Name[0] == 'Z'; }).ToList());
////Code Running in a Methods
int iNameCount = pName.Length;
ICollection<ICity> objCities = null;
if (this.m_iLastNameCount == 0 || iNameCount == 1)
{
objCities = this.m_objCitiesByKey[pName[0]];
this.objLastCities.Clear();
this.objLastCities.Add(objCities);
this.m_iLastNameCount = 1;
}
else
{
if (iNameCount > this.m_iLastNameCount)
{
objCities = this.objLastCities[this.m_iLastNameCount - 1].Where((ICity pCity) =>
{
bool bFound = false;
if (pCity.Name.Length >= pName.Length)
{
bFound = pCity.Name.Substring(0, pName.Length).Equals(pName);
}
return bFound;
}).ToList();
this.objLastCities.Add(objCities);
this.m_iLastNameCount++;
}
else
{
objCities = base.m_objCities.Where((ICity pCity) =>
{
bool bFound = false;
if (pCity.Name.Length >= pName.Length)
{
bFound = pCity.Name.Substring(0, pName.Length).Equals(pName);
}
return bFound;
}).ToList();
this.objLastCities.RemoveAt(iNameCount - 1);
objCities = this.objLastCities[iNameCount - 1];
this.m_iLastNameCount--;
}
this.objLastCities.Add(objCities);
}
return this.objLastCities[this.objLastCities.Count - 1];
根据我在 Stopwatch 类的帮助下得到的结果，更快的脚本是数字 4，但我希望它是数字 5，因为所有城市都在字典中拆分，但不幸的是字典类似乎慢慢来。
那么你们有什么方法可以提高这里的性能吗？
谢谢