mcs/class/Mono.CodeContracts/Mono.CodeContracts.Static.DataStructures/ImmutableSet.cs

   1 //
   2 // ImmutableSet.cs
   3 //
   4 // Authors:
   5 //      Alexander Chebaturkin (chebaturkin@gmail.com)
   6 //
   7 // Copyright (C) 2011 Alexander Chebaturkin
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28
  29 using System;
  30 using System.Collections.Generic;
  31 using System.IO;
  32
  33 namespace Mono.CodeContracts.Static.DataStructures {
  34         class ImmutableSet<T> : IImmutableSet<T>
  35                 where T : IEquatable<T> {
  36                 private readonly IImmutableMap<T, Dummy> underlying;
  37
  38                 public ImmutableSet (IImmutableMap<T, Dummy> immutableMap)
  39                 {
  40                         this.underlying = immutableMap;
  41                 }
  42
  43                 #region Implementation of IImmutableSet<T>
  44                 public T Any
  45                 {
  46                         get { return this.underlying.AnyKey; }
  47                 }
  48
  49                 public int Count
  50                 {
  51                         get { return this.underlying.Count; }
  52                 }
  53
  54                 public IEnumerable<T> Elements
  55                 {
  56                         get { return this.underlying.Keys; }
  57                 }
  58
  59                 public IImmutableSet<T> Add (T item)
  60                 {
  61                         return new ImmutableSet<T> (this.underlying.Add (item, Dummy.Value));
  62                 }
  63
  64                 public IImmutableSet<T> Remove (T item)
  65                 {
  66                         return new ImmutableSet<T> (this.underlying.Remove (item));
  67                 }
  68
  69                 public bool Contains (T item)
  70                 {
  71                         return this.underlying.ContainsKey (item);
  72                 }
  73
  74                 public bool IsContainedIn (IImmutableSet<T> that)
  75                 {
  76                         if (Count > that.Count)
  77                                 return false;
  78                         bool result = true;
  79                         this.underlying.Visit ((e, dummy) => {
  80                                                 if (that.Contains (e))
  81                                                         return VisitStatus.ContinueVisit;
  82
  83                                                 result = false;
  84                                                 return VisitStatus.StopVisit;
  85                                                });
  86                         return result;
  87                 }
  88
  89                 public IImmutableSet<T> Intersect (IImmutableSet<T> that)
  90                 {
  91                         if (this == that)
  92                                 return this;
  93                         if (Count == 0)
  94                                 return this;
  95                         IImmutableSet<T> set;
  96                         IImmutableSet<T> larger;
  97                         if (Count < that.Count) {
  98                                 set = this;
  99                                 larger = that;
 100                         } else {
 101                                 if (that.Count == 0)
 102                                         return that;
 103                                 set = that;
 104                                 larger = this;
 105                         }
 106                         IImmutableSet<T> result = set;
 107                         set.Visit ((e) => {
 108                                         if (!larger.Contains (e))
 109                                                 result = result.Remove (e);
 110                                    });
 111                         return result;
 112                 }
 113
 114                 public IImmutableSet<T> Union (IImmutableSet<T> that)
 115                 {
 116                         if (this == that)
 117                                 return this;
 118                         if (Count == 0)
 119                                 return that;
 120                         IImmutableSet<T> smaller;
 121                         IImmutableSet<T> larger;
 122                         if (Count < that.Count) {
 123                                 smaller = this;
 124                                 larger = that;
 125                         } else {
 126                                 if (that.Count == 0)
 127                                         return this;
 128                                 smaller = that;
 129                                 larger = this;
 130                         }
 131                         IImmutableSet<T> result = larger;
 132                         smaller.Visit (e => { result = result.Add (e); });
 133                         return result;
 134                 }
 135
 136                 public void Visit (Action<T> visitor)
 137                 {
 138                         this.underlying.Visit ((elem, dummy) => {
 139                                                 visitor (elem);
 140                                                 return VisitStatus.ContinueVisit;
 141                                                });
 142                 }
 143
 144                 public void Dump (TextWriter tw)
 145                 {
 146                         tw.Write ("{");
 147                         bool first = true;
 148                         foreach (T key in this.underlying.Keys) {
 149                                 if (!first)
 150                                         tw.Write (", ");
 151                                 else
 152                                         first = false;
 153                                 tw.Write ("{0}", key);
 154                         }
 155                         tw.WriteLine ("}");
 156                 }
 157
 158                 public static IImmutableSet<T> Empty ()
 159                 {
 160                         return new ImmutableSet<T> (ImmutableMap<T, Dummy>.Empty);
 161                 }
 162
 163                 public static IImmutableSet<T> Empty (Func<T, int> keyConverter)
 164                 {
 165                         return new ImmutableSet<T> (ImmutableIntKeyMap<T, Dummy>.Empty (keyConverter));
 166                 }
 167                 #endregion
 168         }
 169 }