问题描述
有没有办法做到在C#中的并行可枚举的foreach
风格迭代?对于标化的名单,我知道人们可以使用普通的在
循环遍历索引范围int,但我真的喜欢的foreach
到为
的多种原因。
Is there a way to do foreach
style iteration over parallel enumerables in C#? For subscriptable lists, I know one could use a regular for
loop iterating an int over the index range, but I really prefer foreach
to for
for a number of reasons.
奖励积分,如果它工作在C#2.0
Bonus points if it works in C# 2.0
推荐答案
简短的回答,没有。 的foreach
同时适用于只有一个枚举。
Short answer, no. foreach
works on only one enumerable at a time.
不过,如果你把你的并行可枚举成一个单一,可以的foreach
过合并。我不知道有任何容易的,建在这样的方法,但下面应该工作(虽然我没有测试过):
However, if you combine your parallel enumerables into a single one, you can foreach
over the combined. I am not aware of any easy, built in method of doing this, but the following should work (though I have not tested it):
public IEnumerable<TSource[]> Combine<TSource>(params object[] sources)
{
foreach(var o in sources)
{
// Choose your own exception
if(!(o is IEnumerable<TSource>)) throw new Exception();
}
var enums =
sources.Select(s => ((IEnumerable<TSource>)s).GetEnumerator())
.ToArray();
while(enums.All(e => e.MoveNext()))
{
yield return enums.Select(e => e.Current).ToArray();
}
}
然后你可以的foreach
在返回枚举:
foreach(var v in Combine(en1, en2, en3))
{
// Remembering that v is an array of the type contained in en1,
// en2 and en3.
}
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