LINQ不等于不起作用？

Question

我正在尝试解决一个问题，我需要管理一个数字范围的数组，并且需要确保集合中的数字范围不会相互冲突。 对于那些已经弄清楚了的人：是的，我在谈论网络，但是我正在尝试简化本文。 :-)

我花了一分钟（或者可能是两分钟），但是我想出了以下逻辑测试：

1. 确定现有的结尾（最后一个）是否小于新的开头（新的第一个）。
2. 确定现有的开头（第一个）是否大于新的结尾（新的最后一个）。
3. 如果＃1的结果与＃2的结果不同，则范围不会冲突。

据我所知（并在Excel中复制），这是合理的逻辑。 但是，当我尝试用C＃在LINQ中编写此逻辑并随后在PowerShell中执行时，它不起作用。 对于冗长的PowerShell输出，我深表歉意。

我应该如何在LINQ中编写此逻辑？ 我哪里做错了？

C＃代码：

public class NumberRange
{
    public int First;
    public int Last;

    public NumberRange()
    {
    }

    public NumberRange(int first, int last)
    {
        First = first;
        Last = last;
    }
}

public class NumberRangeCollection : Collection<NumberRange>
{
    protected override void InsertItem(int index, NumberRange item)
    {
        NumberRange[] existingItem = this.Where(x => ((x.Last < item.First) != (x.First > item.Last))).ToArray();
        if (existingItem.Any()) throw new ArgumentException("New range collides with an existing range.", "item");

        base.InsertItem(index, item);
    }
}

PowerShell命令：

PS> $range1 = New-Object TestLibrary.NumberRange -ArgumentList @(3, 4)
PS> $range2 = New-Object TestLibrary.NumberRange -ArgumentList @(4, 5)
PS> $range3 = New-Object TestLibrary.NumberRange -ArgumentList @(5, 6)
PS> $bigrange = New-Object TestLibrary.NumberRange -ArgumentList @(3, 6)
PS> $b = New-Object TestLibrary.NumberRangeCollection
PS> $b.Add($range1)
PS> $b.Add($bigrange) # This should fail, but doesn't
PS> $b | Format-Table -AutoSize

First Last
----- ----
    3    4
    3    6


PS> $b = New-Object TestLibrary.NumberRangeCollection
PS> $b.Add($range2)
PS> $b.Add($bigrange) # This should fail, but doesn't
PS> $b | Format-Table -AutoSize

First Last
----- ----
    4    5
    3    6


PS> $b = New-Object TestLibrary.NumberRangeCollection
PS> $b.Add($range3)
PS> $b.Add($bigrange) # This should fail, but doesn't
PS> $b | Format-Table -AutoSize

First Last
----- ----
    5    6
    3    6


PS> $b = New-Object TestLibrary.NumberRangeCollection
PS> $b.Add($range4)
PS> $b.Add($bigrange) # This should fail, does, but doesn't throw the right exception.
Exception calling "Add" with "1" argument(s): "Object reference not set to an instance of an object."
At line:1 char:1
+ $b.Add($bigrange)
+ ~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : NullReferenceException

PS> $b | Format-Table -AutoSize
PS> $b = New-Object TestLibrary.NumberRangeCollection
PS> $b.Add($bigrange)
PS> $b.Add($range1) # This should fail, but doesn't
PS> $b.Add($range2) # This should fail, but doesn't
PS> $b.Add($range3) # WOOT!  The only one that works!
Exception calling "Add" with "1" argument(s): "New range collides with an existing range.
Parameter name: item"
At line:1 char:1
+ $b.Add($range3)
+ ~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : ArgumentException

PS> $b.Add($range4) # This should fail, does, but doesn't throw the right exception.
Exception calling "Add" with "1" argument(s): "Object reference not set to an instance of an object."
At line:1 char:1
+ $b.Add($range4)
+ ~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodInvocationException
    + FullyQualifiedErrorId : NullReferenceException

PS> $b | Format-Table -AutoSize

First Last
----- ----
    3    6
    3    4
    4    5

Answer 1

谢谢@JonSkeet，因为我发现这样做的第二个问题，因此建议您重写它。

因此，我的问题的答案有两个：

1. LINQ逻辑很好（使用！=），但是InsertItem中的逻辑相反。 我要么需要将！=更改为==，要么将if (existingItem.Any())更改为if (!existingItem.Any()) 。 我选择了前者。
2. $ range4不存在（其他测试的剩余部分）。 叹

这是完整的工作代码（全部在C＃中）：

public class NumberRange
{
    public int First;
    public int Last;

    public NumberRange()
    {
    }

    public NumberRange(int first, int last)
    {
        First = first;
        Last = last;
    }
}

public class NumberRangeCollection : Collection<NumberRange>
{
    public NumberRange BigRange = new NumberRange(3, 6);
    public NumberRange Range1 = new NumberRange(3, 4);
    public NumberRange Range2 = new NumberRange(4, 5);
    public NumberRange Range3 = new NumberRange(5, 6);

    protected override void InsertItem(int index, NumberRange item)
    {
        NumberRange[] existingItem = this.Where(x => ((x.Last < item.First) == (x.First > item.Last))).ToArray();
        if (existingItem.Any()) throw new ArgumentException("New range collides with an existing range.", "item");

        base.InsertItem(index, item);
    }

    public NumberRangeCollection RunTest1()
    {
        Clear();
        Add(Range1);
        Add(BigRange);
        return this;
    }

    public NumberRangeCollection RunTest2()
    {
        Clear();
        Add(Range2);
        Add(BigRange);
        return this;
    }

    public NumberRangeCollection RunTest3()
    {
        Clear();
        Add(Range3);
        Add(BigRange);
        return this;
    }

    public NumberRangeCollection RunTest4()
    {
        Clear();
        Add(BigRange);
        try
        {
            Add(Range1);
        }
        catch
        {
        }
        try
        {
            Add(Range2);
        }
        catch
        {
        }
        try
        {
            Add(Range3);
        }
        catch
        {
        }
        return this;
    }
}