针对参数失败的自定义比较器

Question

我正在尝试编写一个自定义比较器来根据相似性对搜索结果列表进行排序。我希望最像输入的搜索词的术语首先出现在列表中，然后是以搜索短语开头的短语，然后是按字母顺序排列的所有其他值。

给出这个测试代码：

  string searchTerm = "fleas";
  List<string> list = new List<string>
                                       {
                                           "cat fleas",
                                           "dog fleas",
                                           "advantage fleas",
                                           "my cat has fleas",
                                           "fleas",
                                           "fleas on my cat"
                                       };

我正在尝试使用这个比较器：

public class MatchComparer : IComparer<string>
{
    private readonly string _searchTerm;

    public MatchComparer(string searchTerm)
    {
        _searchTerm = searchTerm;
    }

    public int Compare(string x, string y)
    {
        if (x.Equals(_searchTerm) ||
             y.Equals(_searchTerm))
            return 0;

        if (x.StartsWith(_searchTerm) ||
            y.StartsWith(_searchTerm))
            return 0;

        if (x.Contains(_searchTerm))
            return 1;

        if (y.Contains(_searchTerm))
            return 1;

        return x.CompareTo(y);
    }

调用 list.Sort(new MatchComparer(searchTerm) 会导致“我的猫有跳蚤”位于列表顶部。

我想我一定在这里做了一些奇怪/奇怪的事情..这里有什么问题吗？或者有更好的方法来实现我想要做的事情吗？

谢谢！

Answer 1

的所有可能返回值

您没有首先使用 CompareTo -1 == x
0 == 相等
1 == y 首先

你想要更多类似这样的东西

public class MatchComparer : IComparer<string> 
{ 
    private readonly string _searchTerm; 

    public MatchComparer(string searchTerm) 
    { 
        _searchTerm = searchTerm; 
    } 

    public int Compare(string x, string y) 
    { 
        if (x.Equals(y)) return 0; // Both entries are equal;
        if (x.Equals(_searchTerm)) return -1; // first string is search term so must come first
        if (y.Equals(_searchTerm)) return 1; // second string is search term so must come first
        if (x.StartsWith(_searchTerm)) {
            // first string starts with search term
            // if second string also starts with search term sort alphabetically else first string first
            return (y.StartsWith(_searchTerm)) ? x.CompareTo(y) : -1;
        }; 
        if (y.StartsWith(_searchTerm)) return 1; // second string starts with search term so comes first
        if (x.Contains(_searchTerm)) {
            // first string contains search term
            // if second string also contains the search term sort alphabetically else first string first
            return (y.Contains(_searchTerm)) ? x.CompareTo(y) : -1; 
        }
        if (y.Contains(_searchTerm)) return 1; // second string contains search term so comes first
        return x.CompareTo(y); // fall back on alphabetic
    } 
}