C#：shlwapi.dll 中 StrCmpLogicalW 的实现或替代

Question

为了在我的应用程序中进行自然排序，我当前在 shlwapi.dll 中 P/Invoke 一个名为 StrCmpLogicalW 的函数。我正在考虑尝试在 Mono 下运行我的应用程序，但当然我不能拥有这个 P/Invoke 东西（据我所知）。

是否可以在某处看到该方法的实现，或者是否有一个良好、干净且高效的 C# 代码片段可以执行相同的操作？

我的代码目前如下所示：

[SuppressUnmanagedCodeSecurity]
internal static class SafeNativeMethods
{
    [DllImport("shlwapi.dll", CharSet = CharSet.Unicode)]
    public static extern int StrCmpLogicalW(string psz1, string psz2);
}

public class NaturalStringComparer : IComparer<string>
{
    private readonly int modifier = 1;

    public NaturalStringComparer() : this(false) {}
    public NaturalStringComparer(bool descending)
    {
        if (descending) modifier = -1;
    }

    public int Compare(string a, string b)
    {
        return SafeNativeMethods.StrCmpLogicalW(a ?? "", b ?? "") * modifier;
    }
}

因此，我正在寻找的是上述类的替代方案，它不使用 extern 函数。

Answer 1

我刚刚在 C# 中实现了自然字符串比较，也许有人会发现它很有用：

public class NaturalComparer : IComparer<string>
{
   public int Compare(string x, string y)
   {
      if (x == null && y == null) return 0;
      if (x == null) return -1;
      if (y == null) return 1;

      int lx = x.Length, ly = y.Length;

      for (int mx = 0, my = 0; mx < lx && my < ly; mx++, my++)
      {
         if (char.IsDigit(x[mx]) && char.IsDigit(y[my]))
         {
            long vx = 0, vy = 0;

            for (; mx < lx && char.IsDigit(x[mx]); mx++)
               vx = vx * 10 + x[mx] - '0';

            for (; my < ly && char.IsDigit(y[my]); my++)
               vy = vy * 10 + y[my] - '0';

            if (vx != vy)
               return vx > vy ? 1 : -1;
         }

         if (mx < lx && my < ly && x[mx] != y[my])
            return x[mx] > y[my] ? 1 : -1;
      }

      return lx - ly;
   }
}

Answer 2

http://www.interact-sw.co.uk/iangblog/2007/ 12/13/natural-sorting 似乎就是您要寻找的。

（不，.NET 中没有内置与 StrCmpLogicalW 等效的托管组件）

Answer 3

我使用正则表达式来删除特殊字符。然后转换为 int。然后我比较了整数。

输入 ：

List input = new List{ "6.04","6.01","6.03","6#04" };

Expected Output:

6.01
6.03
6.04
6#04

 var output = input.OrderBy(s => s, new NaturalStringComparer());
            foreach (var sort in output)
            {
                Console.WriteLine(sort);
            }


public struct NaturalStringComparer : IComparer
    {
        public int Compare(string x, string y)
        {
            if (x == null && y == null) return 0;
            if (x == null) return -1;
            if (y == null) return 1;

            int lx = x.Length, ly = y.Length;

            int a = int.Parse(System.Text.RegularExpressions.Regex.Replace(x, @"\D+", ""));
            int b = int.Parse(System.Text.RegularExpressions.Regex.Replace(y, @"\D+", ""));

            return a.CompareTo(b);
        }
    }

Answer 4

如果您运行在 Windows XP 或更高版本上，您可以 PInvoke 到 shell 函数 StrCmpLogicalW：

public static int StrCmpLogical(String s1, String s2)
{
    if (String.IsNullOrEmpty(s1) && !String.IsNullOrEmpty(s2))
        return 1; //empty s1 comes after s2
    else if (String.IsNullOrEmpty(s2) && !String.IsNullOrEmpty(s1))
        return -1; //non-empty string comes before empty

    return SafeNativeMethods.StrCmpLogicalW(s1, s2);
}

然后是内部不安全类：

/// <summary>
/// This class suppresses stack walks for unmanaged code permission. 
/// (System.Security.SuppressUnmanagedCodeSecurityAttribute is applied to this class.) 
/// This class is for methods that are safe for anyone to call. 
/// Callers of these methods are not required to perform a full security review to make sure that the 
/// usage is secure because the methods are harmless for any caller.
/// </summary>
[SuppressUnmanagedCodeSecurity]
internal static class SafeNativeMethods
{
    [DllImport("shlwapi.dll", CharSet = CharSet.Unicode)]
    internal static extern Int32 StrCmpLogicalW(string psz1, string psz2);
}