动态 Linq 中的按位排序

Question

I need to be able to perform a string based, bitwise, .OrderBy in dynamic linq.

items = items.OrderBy(x => (x.Permissions & 65536) != 0);

vs.

items = items.Where("1==1" + where).OrderBy("Permissions & 65536 != 0")

Is this even possible? I don't see any examples for bitwise operators in the download (CSharpSamples.zip\\LinqSamples\\DynamicQuery). I can't get anything to work and I can't find any examples. Help!

Answer 1

You can reorder the columns of the data base on string inputs. The code below is tested and works.

using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Text;

namespace ConsoleApplication75
{
    class Program
    {
         static void Main(string[] args)
        {
            //u = user
            //g = group
            //s = system
            //r = read
            //w = write
            //e = execute

            //array below represents the normal position of the permissions
            List<string> permissions = new List<string>() { "ue", "uw", "ur", "ge", "gw", "gr", "se", "sw", "sr" };

            //below is the order we actually want
            List<string> sortOrder = new List<string>() { "ue", "ge", "se", "uw", "gw", "sw", "ur", "gr", "sr" };

            List<cFile> files = new List<cFile>() {
                new cFile() { name = "A", permission = 0x001},
                new cFile() { name = "B", permission = 0x002},
                new cFile() { name = "C", permission = 0x004},
                new cFile() { name = "D", permission = 0x008},
                new cFile() { name = "E", permission = 0x010},
                new cFile() { name = "F", permission = 0x020},
                new cFile() { name = "G", permission = 0x040},
                new cFile() { name = "H", permission = 0x080},
                new cFile() { name = "I", permission = 0x100}
            };


            //now reorder the columns
             var tempData = files.Select(x => new { files = x, shiftedPermissions =  Enumerable.Range(0, 9).Select(y => (permissions.IndexOf(sortOrder[y]) - y >= 0) ?
                (1 << y) & (x.permission >> (permissions.IndexOf(sortOrder[y]) - y)) :
                (1 << y) & (x.permission << (y - permissions.IndexOf(sortOrder[y])))).Sum()
             }).ToList();

             List<cFile> sortedPermissions = tempData.OrderBy(x => x.shiftedPermissions).Select(x => x.files).ToList();

        }

    }
    public class cFile
    {
        public string name { get; set; }
        public UInt32 permission { get; set; }
    }


}