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