Question

我遇到过问题，其中某些代码在.NET 4.0中按预期运行，但在Mono 2.6（Unity3D）中没有运行。请看一下：

    void Test()
    {
        Func<string, MemberInfo> get = name => typeof(HSTest).GetField(name, BindingFlags.Public | BindingFlags.Instance);
        var m1 = new TestMember { MemberInfo = get("x") };
        var m2 = new TestMember { MemberInfo = get("y") };
        var m3 = new TestMember { MemberInfo = get("x") };
        var m4 = new TestMember { MemberInfo = get("x") };
        var m5 = new TestMember { MemberInfo = get("a") };
        var m6 = new TestMember { MemberInfo = get("b") };
        var l1 = new List<TestMember> { m1, m2, m3 };
        var l2 = new List<TestMember> { m4, m5, m6 };
        var ll = new List<List<TestMember>> { l1, l2 };
        var comparer = new TestMemberComparer();
        var res = IntersectAll(ll, comparer);
        res.Foreach(Debug.Log); // In .NET this prints "x" in Mono it doesn't print anything
    }

    // Credits to Jon Skeet
    public static List<T> IntersectAll<T>(List<List<T>> lists, IEqualityComparer<T> comparer)
    {
        HashSet<T> hashSet = null;
        foreach (var list in lists)
        {
            if (hashSet == null)
            {
                hashSet = new HashSet<T>(list, comparer);
            }
            else
            {
                hashSet.IntersectWith(list);
            }
        }
        return hashSet == null ? new List<T>() : hashSet.ToList();
    }
}

public class TestMember
{
    public MemberInfo MemberInfo { get; set; }
}

public class TestMemberComparer : IEqualityComparer<TestMember>
{
    public bool Equals(TestMember x, TestMember y)
    {
        return x.MemberInfo.Equals(y.MemberInfo);
    }

    public int GetHashCode(TestMember obj)
    {
        return obj.MemberInfo.GetHashCode();
    }
}

public class HSTest
{
    public int x;
    public int y;
    public int z;
    public int a;
    public int b;
    public int c;
}

在.NET中，我得到了＆＃39; x＆＃39;作为交集的结果，在Mono I中没有得到任何回报。

有什么想法吗？

编辑：

使用名称而不是实际的MemberInfo对象不会有任何帮助

public class TestMemberComparer : IEqualityComparer<TestMember>
{
    public bool Equals(TestMember x, TestMember y)
    {
        return x.MemberInfo.Name.Equals(y.MemberInfo.Name);
    }

    public int GetHashCode(TestMember obj)
    {
        return obj.MemberInfo.Name.GetHashCode();
    }
}

我还应该提一下，使用不同的交叉方式不会导致任何问题（在MemberInfo和MemberInfo.Name中使用GetHashCode和Equals时都会出现问题）：

var res = ll.Aggregate((p, n) => p.Intersect(n, comparer).ToList());

编辑：这是一个测试，在比较器中有一些日志

    void Test()
    {
        // ... define everything like in previous code
        var comparer = new TestMemberComparer();
        var hs = new HashSet<TestMember>(l1, comparer);
        hs.IntersectWith(l2);
        hs.ToList().Foreach(Debug.Log);
    }

public class TestMemberComparer : IEqualityComparer<TestMember>
{
    public bool Equals(TestMember left, TestMember right)
    {
        bool result = left.MemberInfo.Name.Equals(right.MemberInfo.Name);
        Debug.Log("Comparing `" + left.MemberInfo.Name + "` with `" + right.MemberInfo.Name + "` Result: " + result);
        return result;
    }

    public int GetHashCode(TestMember obj)
    {
        int hc = obj.MemberInfo.Name.GetHashCode();
        Debug.Log("Hash code: " + hc);
        return hc;
    }
}

执行时我得到的是：

Hash code: 120
Hash code: 120
Hash code: 121
Comparing `x` with `x` Result: True
Hash code: 120
Hash code: 120
Hash code: 120
Comparing `x` with `x` Result: True
Hash code: 121
Comparing `y` with `y` Result: True
Hash code: 97
Hash code: 97
Hash code: 98
Hash code: 98

Answer 1

我怀疑这只是MemberInfo.Equals无法正常工作的问题。这很容易测试：

var m1 = get("x");
var m2 = get("x");
Console.WriteLine(m1.Equals(m2));

如果打印出False，那就是问题，你应该添加自己的缓存。

使用自定义IEqualityComparer的HashSet.IntersectWIth在Mono中产生错误的结果

1 个答案: