beagled/Lucene.Net/Util/Parameter.cs

   1 /*
   2  * Copyright 2005 The Apache Software Foundation
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 using System;
  17 namespace Lucene.Net.Util
  18 {
  19
  20     /// <summary> A serializable Enum class.</summary>
  21     [Serializable]
  22     public abstract class Parameter
  23     {
  24         internal static System.Collections.IDictionary allParameters = new System.Collections.Hashtable();
  25
  26         private System.String name;
  27
  28         private Parameter()
  29         {
  30             // typesafe enum pattern, no public constructor
  31         }
  32
  33         protected internal Parameter(System.String name)
  34         {
  35             // typesafe enum pattern, no public constructor
  36             this.name = name;
  37             System.String key = MakeKey(name);
  38
  39             if (allParameters.Contains(key))
  40                 throw new System.ArgumentException("Parameter name " + key + " already used!");
  41
  42             allParameters[key] = this;
  43         }
  44
  45         private System.String MakeKey(System.String name)
  46         {
  47             return GetType() + " " + name;
  48         }
  49
  50         public override System.String ToString()
  51         {
  52             return name;
  53         }
  54
  55         /// <summary> Resolves the deserialized instance to the local reference for accurate
  56         /// equals() and == comparisons.
  57         ///
  58         /// </summary>
  59         /// <returns> a reference to Parameter as resolved in the local VM
  60         /// </returns>
  61         /// <throws>  ObjectStreamException </throws>
  62         protected internal virtual System.Object ReadResolve()
  63         {
  64             System.Object par = allParameters[MakeKey(name)];
  65
  66             if (par == null)
  67                 throw new System.IO.IOException("Unknown parameter value: " + name);
  68
  69             return par;
  70         }
  71     }
  72 }