mcs/class/corlib/System.Collections/Stack.cs

   1 //\r
   2 // System.Collections.Stack\r
   3 //\r
   4 // Author:\r
   5 //    Garrett Rooney (rooneg@electricjellyfish.net)\r
   6 //\r
   7 // (C) 2001 Garrett Rooney\r
   8 //\r
   9 \r
  10 namespace System.Collections {\r
  11 \r
  12         public class Stack : ICollection, IEnumerable, ICloneable {\r
  13 \r
  14                 // properties\r
  15                 private object[] contents;\r
  16                 private int current = -1;\r
  17                 private int count = 0;\r
  18                 private int capacity = 16;\r
  19                 private int modCount = 0;\r
  20 \r
  21                 private void Resize(int ncapacity) {\r
  22                         object[] ncontents = new object[ncapacity];\r
  23 \r
  24                         Array.Copy(contents, ncontents, count);\r
  25 \r
  26                         capacity = ncapacity;\r
  27                         contents = ncontents;\r
  28                 }\r
  29 \r
  30                 public Stack() {\r
  31                         contents = new object[capacity];\r
  32                 }\r
  33 \r
  34                 public Stack(ICollection collection) {\r
  35                         capacity = collection.Count;\r
  36                         contents = new object[capacity];\r
  37                         current = capacity - 1;\r
  38                         count = capacity;\r
  39 \r
  40                         collection.CopyTo(contents, 0);\r
  41                 }\r
  42 \r
  43                 public Stack(int c) {\r
  44                         capacity = c;\r
  45                         contents = new object[capacity];\r
  46                 }\r
  47 \r
  48                 private class SyncStack : Stack {\r
  49 \r
  50                         Stack stack;\r
  51 \r
  52                         public SyncStack(Stack s) {\r
  53                                 stack = s;\r
  54                         }\r
  55                         \r
  56                         public override int Count {\r
  57                                 get { \r
  58                                         lock (stack) {\r
  59                                                 return stack.Count; \r
  60                                         }\r
  61                                 }\r
  62                         }\r
  63                         \r
  64                         public override bool IsReadOnly {\r
  65                                 get { \r
  66                                         lock (stack) {\r
  67                                                 return stack.IsReadOnly; \r
  68                                         }\r
  69                                 }\r
  70                         }\r
  71                         \r
  72                         public override bool IsSynchronized {\r
  73                                 get { return true; }\r
  74                         }\r
  75                         \r
  76                         public override object SyncRoot {\r
  77                                 get { return stack.SyncRoot; }\r
  78                         }\r
  79 \r
  80                         public override void Clear() {\r
  81                                 lock(stack) { stack.Clear(); }\r
  82                         }\r
  83 \r
  84                         public override object Clone() {\r
  85                                 lock (stack) { \r
  86                                         return Stack.Synchronized((Stack)stack.Clone()); \r
  87                                 }\r
  88                         }\r
  89 \r
  90                         public override bool Contains(object obj) {\r
  91                                 lock (stack) { return stack.Contains(obj); }\r
  92                         }\r
  93 \r
  94                         public override void CopyTo(Array array, int index) {\r
  95                                 lock (stack) { stack.CopyTo(array, index); }\r
  96                         }\r
  97 \r
  98                         public override IEnumerator GetEnumerator() {\r
  99                                 lock (stack) { \r
 100                                         return new Enumerator(stack); \r
 101                                 }\r
 102                         }\r
 103 \r
 104                         public override object Peek() {\r
 105                                 lock (stack) { return stack.Peek(); }\r
 106                         }\r
 107 \r
 108                         public override object Pop() {\r
 109                                 lock (stack) { return stack.Pop(); }\r
 110                         }\r
 111 \r
 112                         public override void Push(object obj) {\r
 113                                 lock (stack) { stack.Push(obj); }\r
 114                         }\r
 115 \r
 116                         public override object[] ToArray() {\r
 117                                 lock (stack) { return stack.ToArray(); }\r
 118                         }\r
 119                 }\r
 120 \r
 121                 public static Stack Synchronized(Stack s) {\r
 122                         if (s == null) {\r
 123                                 throw new ArgumentNullException();\r
 124                         }\r
 125 \r
 126                         return new SyncStack(s);\r
 127                 }\r
 128 \r
 129                 public virtual int Count {\r
 130                         get { return count; }\r
 131                 }\r
 132 \r
 133                 public virtual bool IsReadOnly {\r
 134                         get { return false; }\r
 135                 }\r
 136 \r
 137                 public virtual bool IsSynchronized {\r
 138                         get { return false; }\r
 139                 }\r
 140 \r
 141                 public virtual object SyncRoot {\r
 142                         get { return this; }\r
 143                 }\r
 144 \r
 145                 public virtual void Clear() {\r
 146                         modCount++;\r
 147 \r
 148                         for (int i = 0; i < count; i++) {\r
 149                                 contents[i] = null;\r
 150                         }\r
 151 \r
 152                         count = 0;\r
 153                         current = -1;\r
 154                 }\r
 155 \r
 156                 public virtual object Clone() {\r
 157                         Stack stack;\r
 158 \r
 159                         stack = new Stack();\r
 160 \r
 161                         stack.current = current;\r
 162                         stack.contents = contents;\r
 163                         stack.count = count;\r
 164                         stack.capacity = capacity;\r
 165 \r
 166                         return stack;\r
 167                 }\r
 168 \r
 169                 public virtual bool Contains(object obj) {\r
 170                         if (count == 0)\r
 171                                 return false;\r
 172 \r
 173                         for (int i = 0; i < count; i++) {\r
 174                                 if (contents[i].Equals(obj))\r
 175                                         return true; \r
 176                         }\r
 177 \r
 178                         return false;\r
 179                 }\r
 180 \r
 181                 public virtual void CopyTo (Array array, int index) {\r
 182                         if (array == null) {\r
 183                                 throw new ArgumentNullException();\r
 184                         }\r
 185 \r
 186                         if (index < 0) {\r
 187                                 throw new ArgumentOutOfRangeException();\r
 188                         }\r
 189 \r
 190                         if (array.Rank > 1 || \r
 191                             index >= array.Length || \r
 192                             count > array.Length - index) {\r
 193                                 throw new ArgumentException();\r
 194                         }\r
 195 \r
 196                         for (int i = current; i != -1; i--) {\r
 197                                 array.SetValue(contents[i], \r
 198                                                count - (i + 1) + index);\r
 199                         }\r
 200                 }\r
 201 \r
 202                 private class Enumerator : IEnumerator {\r
 203 \r
 204                         Stack stack;\r
 205                         private int modCount;\r
 206                         private int current;\r
 207 \r
 208                         internal Enumerator(Stack s) {\r
 209                                 // this is odd.  it seems that you need to \r
 210                                 // start one further ahead than current, since \r
 211                                 // MoveNext() gets called first when using an \r
 212                                 // Enumeration...\r
 213                                 stack = s;\r
 214                                 modCount = s.modCount;\r
 215                                 current = s.current + 1;\r
 216                         }\r
 217 \r
 218                         public virtual object Current {\r
 219                                 get {\r
 220                                         if (modCount != stack.modCount \r
 221                                             || current == -1 \r
 222                                             || current > stack.count)\r
 223                                                 throw new InvalidOperationException();\r
 224                                         return stack.contents[current];\r
 225                                 }\r
 226                         }\r
 227 \r
 228                         public virtual bool MoveNext() {\r
 229                                 if (modCount != stack.modCount \r
 230                                     || current == -1) {\r
 231                                         throw new InvalidOperationException();\r
 232                                 }\r
 233 \r
 234                                 current--;\r
 235 \r
 236                                 if (current == -1) {\r
 237                                         return false;\r
 238                                 } else {\r
 239                                         return true;\r
 240                                 }\r
 241                         }\r
 242 \r
 243                         public virtual void Reset() {\r
 244                                 if (modCount != stack.modCount) {\r
 245                                         throw new InvalidOperationException();\r
 246                                 }\r
 247 \r
 248                                 // start one ahead of stack.current, so the \r
 249                                 // first MoveNext() will put us at the top\r
 250                                 current = stack.current + 1;\r
 251                         }\r
 252                 }\r
 253 \r
 254                 public virtual IEnumerator GetEnumerator() {\r
 255                         return new Enumerator(this);\r
 256                 }\r
 257 \r
 258                 public virtual object Peek() {\r
 259                         if (current == -1) {\r
 260                                 throw new InvalidOperationException();\r
 261                         } else {\r
 262                                 return contents[current];\r
 263                         }\r
 264                 }\r
 265 \r
 266                 public virtual object Pop() {\r
 267                         if (current == -1) {\r
 268                                 throw new InvalidOperationException();\r
 269                         } else {\r
 270                                 modCount++;\r
 271 \r
 272                                 object ret = contents[current];\r
 273                 \r
 274                                 count--;\r
 275                                 current--;\r
 276 \r
 277                                 // if we're down to capacity/4, go back to a \r
 278                                 // lower array size.  this should keep us from \r
 279                                 // sucking down huge amounts of memory when \r
 280                                 // putting large numbers of items in the Stack.\r
 281                                 // if we're lower than 16, don't bother, since \r
 282                                 // it will be more trouble than it's worth.\r
 283                                 if (count <= (capacity/4) && count > 16) {\r
 284                                         Resize(capacity/2);\r
 285                                 }\r
 286 \r
 287                                 return ret;\r
 288                         }\r
 289                 }\r
 290 \r
 291                 public virtual void Push(Object o) {\r
 292                         modCount++;\r
 293 \r
 294                         if (capacity == count) {\r
 295                                 Resize(capacity * 2);\r
 296                         }\r
 297 \r
 298                         count++;\r
 299                         current++;\r
 300 \r
 301                         contents[current] = o;\r
 302                 }\r
 303 \r
 304                 public virtual object[] ToArray() {\r
 305                         object[] ret = new object[count];\r
 306 \r
 307                         Array.Copy(contents, ret, count);\r
 308 \r
 309                         // ret needs to be in LIFO order\r
 310                         Array.Reverse(ret);\r
 311 \r
 312                         return ret;\r
 313                 }\r
 314         }\r
 315 }\r