mcs/class/Mono.CodeContracts/Mono.CodeContracts.Static.Lattices/EnvironmentDomain.cs

   1 //
   2 // EnvironmentDomain.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 using System.Linq;
  33
  34 using Mono.CodeContracts.Static.DataStructures;
  35
  36 namespace Mono.CodeContracts.Static.Lattices {
  37         class EnvironmentDomain<K, V> : IAbstractDomain<EnvironmentDomain<K, V>>
  38                 where V : IAbstractDomain<V>
  39                 where K : IEquatable<K> {
  40                 readonly IImmutableMapFactory<K, V> factory;
  41                 readonly IImmutableMap<K, V> map;
  42
  43                 EnvironmentDomain (IImmutableMapFactory<K, V> factory)
  44                         : this (factory, factory.Empty)
  45                 {
  46                 }
  47
  48                 EnvironmentDomain (IImmutableMap<K, V> map)
  49                         : this (map.Factory (), map)
  50                 {
  51                 }
  52
  53                 EnvironmentDomain (IImmutableMapFactory<K, V> factory, IImmutableMap<K, V> map)
  54                 {
  55                         this.factory = factory;
  56                         this.map = map;
  57                 }
  58
  59                 public V this [K key] { get { return map == null ? default(V) : map[key]; } }
  60
  61                 public IEnumerable<K> Keys { get { return map.Keys; } }
  62
  63                 #region IAbstractDomain<EnvironmentDomain<K,V>> Members
  64
  65                 public EnvironmentDomain<K, V> Top { get { return new EnvironmentDomain<K, V> (factory.Empty); } }
  66
  67                 public EnvironmentDomain<K, V> Bottom { get { return new EnvironmentDomain<K, V> (factory, null); } }
  68
  69                 public bool IsTop { get { return map != null && map.Count == 0; } }
  70
  71                 public bool IsBottom { get { return map == null; } }
  72
  73                 public EnvironmentDomain<K, V> Join (EnvironmentDomain<K, V> that)
  74                 {
  75                         return JoinOrWiden (that, (a, b) => a.Join (b));
  76                 }
  77
  78                 public EnvironmentDomain<K, V> Widen (EnvironmentDomain<K, V> that)
  79                 {
  80                         return JoinOrWiden (that, (a, b) => a.Widen (b));
  81                 }
  82
  83                 EnvironmentDomain<K, V> JoinOrWiden (EnvironmentDomain<K, V> that, Func<V, V, V> op)
  84                 {
  85                         if (ReferenceEquals (map, that.map) || IsBottom)
  86                                 return that;
  87                         if (that.IsBottom)
  88                                 return this;
  89
  90                         IImmutableMap<K, V> min;
  91                         IImmutableMap<K, V> max;
  92                         GetMinAndMaxByCount (map, that.map, out min, out max);
  93
  94                         var result = min; // intersection of keys
  95                         foreach (var key in min.Keys) {
  96                                 V thatValue;
  97                                 if (max.TryGetValue (key, out thatValue)) {
  98                                         var join = op (min[key], thatValue);
  99                                         if (join.IsBottom)
 100                                                 return Bottom;
 101
 102                                         result = join.IsTop ? result.Remove (key) : result.Add (key, join);
 103                                 }
 104                                 else
 105                                         result = result.Remove (key);
 106                         }
 107
 108                         return new EnvironmentDomain<K, V> (result);
 109                 }
 110
 111                 public EnvironmentDomain<K, V> Join (EnvironmentDomain<K, V> that, bool widening, out bool weaker)
 112                 {
 113                         //todo: remove it
 114
 115                         weaker = false;
 116                         if (map == that.map || IsTop)
 117                                 return this;
 118                         if (that.IsTop) {
 119                                 weaker = !IsTop;
 120                                 return that;
 121                         }
 122                         if (IsBottom) {
 123                                 weaker = !that.IsBottom;
 124                                 return that;
 125                         }
 126                         if (that.IsBottom)
 127                                 return this;
 128
 129                         IImmutableMap<K, V> min;
 130                         IImmutableMap<K, V> max;
 131                         GetMinAndMaxByCount (map, that.map, out min, out max);
 132
 133                         var intersect = min;
 134                         foreach (var key in min.Keys) {
 135                                 if (!max.ContainsKey (key))
 136                                         intersect = intersect.Remove (key);
 137                                 else {
 138                                         bool keyWeaker;
 139                                         var join = min[key].Join (max[key], widening, out keyWeaker);
 140                                         if (keyWeaker) {
 141                                                 weaker = true;
 142                                                 intersect = join.IsTop ? intersect.Remove (key) : intersect.Add (key, join);
 143                                         }
 144                                 }
 145                         }
 146
 147                         weaker |= intersect.Count < map.Count;
 148                         return new EnvironmentDomain<K, V> (intersect);
 149                 }
 150
 151                 public EnvironmentDomain<K, V> Meet (EnvironmentDomain<K, V> that)
 152                 {
 153                         if (ReferenceEquals (map, that.map))
 154                                 return this;
 155                         if (IsTop)
 156                                 return that;
 157                         if (that.IsTop || IsBottom)
 158                                 return this;
 159                         if (that.IsBottom)
 160                                 return that;
 161
 162                         IImmutableMap<K, V> min;
 163                         IImmutableMap<K, V> max;
 164                         GetMinAndMaxByCount (map, that.map, out min, out max);
 165
 166                         var union = max;
 167                         foreach (var key in min.Keys) {
 168                                 if (!max.ContainsKey (key))
 169                                         union = union.Add (key, min[key]);
 170                                 else {
 171                                         var meet = min[key].Meet (max[key]);
 172                                         union = union.Add (key, meet);
 173                                 }
 174                         }
 175
 176                         return new EnvironmentDomain<K, V> (union);
 177                 }
 178
 179                 public bool LessEqual (EnvironmentDomain<K, V> that)
 180                 {
 181                         bool result;
 182                         if (this.TryTrivialLessEqual (that, out result))
 183                                 return result;
 184
 185                         if (map.Count < that.map.Count)
 186                                 return false;
 187
 188                         return that.map.Keys.All (key => map.ContainsKey (key) && map[key].LessEqual (that.map[key]));
 189                 }
 190
 191                 public EnvironmentDomain<K, V> ImmutableVersion ()
 192                 {
 193                         return this;
 194                 }
 195
 196                 public EnvironmentDomain<K, V> Clone ()
 197                 {
 198                         return this;
 199                 }
 200
 201                 public void Dump (TextWriter tw)
 202                 {
 203                         if (IsTop)
 204                                 tw.WriteLine ("Top");
 205                         else if (IsBottom)
 206                                 tw.WriteLine (this.BottomSymbolIfAny ());
 207                         else {
 208                                 map.Visit ((k, v) => {
 209                                         tw.WriteLine ("{0} -> {1}", k, v);
 210                                         return VisitStatus.ContinueVisit;
 211                                 });
 212                         }
 213                 }
 214
 215                 #endregion
 216
 217                 public static EnvironmentDomain<K, V> TopValue (Func<K, int> keyConverter)
 218                 {
 219                         if (keyConverter == null)
 220                                 throw new ArgumentNullException ("keyConverter");
 221
 222                         return new EnvironmentDomain<K, V> (ImmutableIntKeyMap<K, V>.Empty (keyConverter));
 223                 }
 224
 225                 public static EnvironmentDomain<K, V> TopValue ()
 226                 {
 227                         return new EnvironmentDomain<K, V> (ImmutableMap<K, V>.Empty);
 228                 }
 229
 230                 public static EnvironmentDomain<K, V> BottomValue (Func<K, int> keyConverter)
 231                 {
 232                         if (keyConverter == null)
 233                                 throw new ArgumentNullException ("keyConverter");
 234
 235                         return new EnvironmentDomain<K, V> (ImmutableIntKeyMap<K, V>.Empty (keyConverter).Factory (), null);
 236                 }
 237
 238                 public static EnvironmentDomain<K, V> BottomValue ()
 239                 {
 240                         return new EnvironmentDomain<K, V> (ImmutableMap<K, V>.Empty.Factory (), null);
 241                 }
 242
 243                 public EnvironmentDomain<K, V> With (K key, V value)
 244                 {
 245                         if (value.IsTop)
 246                                 return Without (key);
 247
 248                         return new EnvironmentDomain<K, V> (map.Add (key, value));
 249                 }
 250
 251                 public EnvironmentDomain<K, V> RefineWith (K key, V value)
 252                 {
 253                         V old;
 254                         if (map.TryGetValue (key, out old))
 255                                 value = value.Meet (old);
 256
 257                         return With (key, value);
 258                 }
 259
 260                 public EnvironmentDomain<K, V> Without (K key)
 261                 {
 262                         return new EnvironmentDomain<K, V> (map.Remove (key));
 263                 }
 264
 265                 public bool Contains (K key)
 266                 {
 267                         return map != null && map.ContainsKey (key);
 268                 }
 269
 270                 public bool TryGetValue (K key, out V value)
 271                 {
 272                         if (map == null)
 273                                 return false.Without (out value);
 274
 275                         return map.TryGetValue (key, out value);
 276                 }
 277
 278                 public EnvironmentDomain<K, V> Empty ()
 279                 {
 280                         return new EnvironmentDomain<K, V> (factory.Empty);
 281                 }
 282
 283                 static bool GetMinAndMaxByCount
 284                         (IImmutableMap<K, V> a, IImmutableMap<K, V> b,
 285                          out IImmutableMap<K, V> min, out IImmutableMap<K, V> max)
 286                 {
 287                         if (a.Count < b.Count) {
 288                                 min = a;
 289                                 max = b;
 290                                 return true;
 291                         }
 292                         max = a;
 293                         min = b;
 294                         return false;
 295                 }
 296                 }
 297 }