LINQ不等於不起作用？

Question

我正在嘗試解決一個問題，我需要管理一個數字范圍的數組，並且需要確保集合中的數字范圍不會相互沖突。 對於那些已經弄清楚了的人：是的，我在談論網絡，但是我正在嘗試簡化本文。 :-)

我花了一分鍾（或者可能是兩分鍾），但是我想出了以下邏輯測試：

1. 確定現有的結尾（最后一個）是否小於新的開頭（新的第一個）。
2. 確定現有的開頭（第一個）是否大於新的結尾（新的最后一個）。
3. 如果＃1的結果與＃2的結果不同，則范圍不會沖突。

據我所知（並在Excel中復制），這是合理的邏輯。 但是，當我嘗試用C＃在LINQ中編寫此邏輯並隨后在PowerShell中執行時，它不起作用。 對於冗長的PowerShell輸出，我深表歉意。

我應該如何在LINQ中編寫此邏輯？ 我哪里做錯了？

C＃代碼：

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

謝謝@JonSkeet，因為我發現這樣做的第二個問題，因此建議您重寫它。

因此，我的問題的答案有兩個：

1. LINQ邏輯很好（使用！=），但是InsertItem中的邏輯相反。 我要么需要將！=更改為==，要么將if (existingItem.Any())更改為if (!existingItem.Any()) 。 我選擇了前者。
2. $ range4不存在（其他測試的剩余部分）。 嘆

這是完整的工作代碼（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;
    }
}