wvdotnet/wvmoniker.cs

   1 /*
   2  * Versaplex:
   3  *   Copyright (C)2007-2008 Versabanq Innovations Inc. and contributors.
   4  *       See the included file named LICENSE for license information.
   5  */
   6 using System;
   7 using System.Collections.Generic;
   8 using System.Reflection;
   9 using Wv;
  10 using Wv.Extensions;
  11
  12 namespace Wv
  13 {
  14     public class WvMonikerAttribute : Attribute
  15         { }
  16
  17     public class WvMonikerBase
  18     {
  19         static object lockobj = new Object();
  20         static bool registered = false;
  21
  22         protected static void register_all()
  23         {
  24             if (!registered)
  25             {
  26                 // feebly attempt to be threadsafe: prevent registrations from
  27                 // running except in one thread.
  28                 lock(lockobj)
  29                 {
  30                     if (registered) return;
  31
  32                     foreach (var t in
  33                              WvReflection.find_types(typeof(WvMonikerAttribute)))
  34                     {
  35                         t.InvokeMember("wvmoniker_register",
  36                                        BindingFlags.Static
  37                                          | BindingFlags.Public
  38                                          | BindingFlags.InvokeMethod,
  39                                        null, null, null);
  40                     }
  41                     registered = true;
  42                 }
  43             }
  44         }
  45     }
  46
  47     public class WvMoniker<T>: WvMonikerBase
  48     {
  49         static List<WvMoniker<T>> registry = new List<WvMoniker<T>>();
  50         string prefix;
  51         Func<string,object,T> func;
  52
  53         public static WvMoniker<T>
  54             register(string prefix, Func<string,object,T> func)
  55         {
  56             return new WvMoniker<T>(prefix, func);
  57         }
  58
  59         public WvMoniker(string prefix, Func<string,object,T> func)
  60         {
  61             this.prefix = prefix;
  62             this.func = func;
  63             registry.Add(this);
  64         }
  65
  66         // probably nobody will ever call this
  67         public void unregister()
  68         {
  69             registry.Remove(this);
  70         }
  71
  72         public static WvMoniker<T> find(string prefix)
  73         {
  74             foreach (WvMoniker<T> m in registry)
  75                 if (m.prefix == prefix)
  76                     return m;
  77             return null;
  78         }
  79
  80         public static T create(string moniker, object o)
  81         {
  82             register_all();
  83
  84             int pos = moniker.IndexOf(':');
  85             string prefix, suffix;
  86             if (pos >= 0)
  87             {
  88                 prefix = moniker.Substring(0, pos);
  89                 suffix = moniker.Substring(pos+1);
  90             }
  91             else
  92             {
  93                 prefix = moniker;
  94                 suffix = "";
  95             }
  96
  97             WvMoniker<T> m = find(prefix);
  98             if (m == null)
  99                 return default(T);
 100             else
 101                 return m.func(suffix, o);
 102         }
 103
 104         public static T create(string moniker)
 105         {
 106             return create(moniker, null);
 107         }
 108     }
 109 }