mcs/class/System/System.Collections.Generic/Queue.cs

   1 //
   2 // System.Collections.Generic.Queue
   3 //
   4 // Author:
   5 //    Martin Baulig (martin@ximian.com)
   6 //    Ben Maurer (bmaurer@ximian.com)
   7 //
   8 // (C) 2003, 2004 Novell, Inc.
   9 //
  10
  11 //
  12 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  13 //
  14 // Permission is hereby granted, free of charge, to any person obtaining
  15 // a copy of this software and associated documentation files (the
  16 // "Software"), to deal in the Software without restriction, including
  17 // without limitation the rights to use, copy, modify, merge, publish,
  18 // distribute, sublicense, and/or sell copies of the Software, and to
  19 // permit persons to whom the Software is furnished to do so, subject to
  20 // the following conditions:
  21 //
  22 // The above copyright notice and this permission notice shall be
  23 // included in all copies or substantial portions of the Software.
  24 //
  25 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  26 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  27 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  28 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  29 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  30 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  31 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  32 //
  33
  34 using System;
  35 using System.Runtime.InteropServices;
  36 using System.Diagnostics;
  37
  38 namespace System.Collections.Generic
  39 {
  40         [ComVisible(false)]
  41         [Serializable]
  42         [DebuggerDisplay ("Count={Count}")]
  43         [DebuggerTypeProxy (typeof (CollectionDebuggerView))]
  44         public class Queue<T> : IEnumerable <T>, ICollection, IEnumerable
  45         {
  46                 T [] _array;
  47                 int _head;
  48                 int _tail;
  49                 int _size;
  50                 int _version;
  51
  52                 private const int INITIAL_SIZE = 16;
  53
  54                 public Queue ()
  55                 {
  56                 }
  57
  58                 public Queue (int count)
  59                 {
  60                         if (count < 0)
  61                                 throw new ArgumentOutOfRangeException ("count");
  62
  63                         _array = new T [count];
  64                 }
  65
  66                 public Queue (IEnumerable <T> collection)
  67                 {
  68                         if (collection == null)
  69                                 throw new ArgumentNullException ("collection");
  70
  71                         foreach (T t in collection)
  72                                 Enqueue (t);
  73                 }
  74
  75                 public void Clear ()
  76                 {
  77                         if (_array != null)
  78                                 Array.Clear (_array, 0, _array.Length);
  79
  80                         _head = _tail = _size = 0;
  81                         _version++;
  82                 }
  83
  84                 public bool Contains (T item)
  85                 {
  86                         if (item == null) {
  87                                 foreach (T t in this)
  88                                         if (t == null)
  89                                                 return true;
  90                         } else {
  91                                 foreach (T t in this)
  92                                         if (item.Equals (t))
  93                                                 return true;
  94                         }
  95
  96                         return false;
  97                 }
  98
  99                 public void CopyTo (T [] array, int idx)
 100                 {
 101                         if (array == null)
 102                                 throw new ArgumentNullException ();
 103
 104                         ((ICollection) this).CopyTo (array, idx);
 105                 }
 106
 107                 void ICollection.CopyTo (Array array, int idx)
 108                 {
 109                         if (array == null)
 110                                 throw new ArgumentNullException ();
 111
 112                         if ((uint) idx > (uint) array.Length)
 113                                 throw new ArgumentOutOfRangeException ();
 114
 115                         if (array.Length - idx < _size)
 116                                 throw new ArgumentOutOfRangeException ();
 117
 118                         if (_size == 0)
 119                                 return;
 120
 121                         try {
 122                                 int contents_length = _array.Length;
 123                                 int length_from_head = contents_length - _head;
 124
 125                                 Array.Copy (_array, _head, array, idx, Math.Min (_size, length_from_head));
 126                                 if (_size > length_from_head)
 127                                         Array.Copy (_array, 0, array,
 128                                                     idx  + length_from_head,
 129                                                     _size - length_from_head);
 130                         } catch (ArrayTypeMismatchException) {
 131                                 throw new ArgumentException ();
 132                         }
 133                 }
 134
 135                 public T Dequeue ()
 136                 {
 137                         T ret = Peek ();
 138
 139                         // clear stuff out to make the GC happy
 140                         _array [_head] = default (T);
 141
 142                         if (++_head == _array.Length)
 143                                 _head = 0;
 144                         _size --;
 145                         _version ++;
 146
 147                         return ret;
 148                 }
 149
 150                 public T Peek ()
 151                 {
 152                         if (_size == 0)
 153                                 throw new InvalidOperationException ();
 154
 155                         return _array [_head];
 156                 }
 157
 158                 public void Enqueue (T item)
 159                 {
 160                         if (_array == null || _size == _array.Length)
 161                                 SetCapacity (Math.Max (_size * 2, 4));
 162
 163                         _array [_tail] = item;
 164
 165                         if (++_tail == _array.Length)
 166                                 _tail = 0;
 167
 168                         _size ++;
 169                         _version ++;
 170                 }
 171
 172                 public T [] ToArray ()
 173                 {
 174                         T [] t = new T [_size];
 175                         CopyTo (t, 0);
 176                         return t;
 177                 }
 178
 179                 public void TrimExcess ()
 180                 {
 181                         if (_array != null && (_size < _array.Length * 0.9))
 182                                 SetCapacity (_size);
 183                 }
 184
 185                 void SetCapacity (int new_size)
 186                 {
 187                         if (_array != null && new_size == _array.Length)
 188                                 return;
 189
 190                         if (new_size < _size)
 191                                 throw new InvalidOperationException ("shouldnt happen");
 192
 193                         T [] new_data = new T [new_size];
 194                         if (_size > 0)
 195                                 CopyTo (new_data, 0);
 196
 197                         _array = new_data;
 198                         _tail = _size;
 199                         _head = 0;
 200                         _version ++;
 201                 }
 202
 203                 public int Count {
 204                         get { return _size; }
 205                 }
 206
 207                 bool ICollection.IsSynchronized {
 208                         get { return false; }
 209                 }
 210
 211                 object ICollection.SyncRoot {
 212                         get { return this; }
 213                 }
 214
 215                 public Enumerator GetEnumerator ()
 216                 {
 217                         return new Enumerator (this);
 218                 }
 219
 220                 IEnumerator <T> IEnumerable<T>.GetEnumerator ()
 221                 {
 222                         return GetEnumerator ();
 223                 }
 224
 225                 IEnumerator IEnumerable.GetEnumerator ()
 226                 {
 227                         return GetEnumerator ();
 228                 }
 229
 230                 [Serializable]
 231                 public struct Enumerator : IEnumerator <T>, IEnumerator, IDisposable {
 232                         const int NOT_STARTED = -2;
 233
 234                         // this MUST be -1, because we depend on it in move next.
 235                         // we just decr the _size, so, 0 - 1 == FINISHED
 236                         const int FINISHED = -1;
 237
 238                         Queue <T> q;
 239                         int idx;
 240                         int ver;
 241
 242                         internal Enumerator (Queue <T> q)
 243                         {
 244                                 this.q = q;
 245                                 idx = NOT_STARTED;
 246                                 ver = q._version;
 247                         }
 248
 249                         // for some fucked up reason, MSFT added a useless dispose to this class
 250                         // It means that in foreach, we must still do a try/finally. Broken, very
 251                         // broken.
 252                         public void Dispose ()
 253                         {
 254                                 idx = NOT_STARTED;
 255                         }
 256
 257                         public bool MoveNext ()
 258                         {
 259                                 if (ver != q._version)
 260                                         throw new InvalidOperationException ();
 261
 262                                 if (idx == NOT_STARTED)
 263                                         idx = q._size;
 264
 265                                 return idx != FINISHED && -- idx != FINISHED;
 266                         }
 267
 268                         public T Current {
 269                                 get {
 270                                         if (idx < 0)
 271                                                 throw new InvalidOperationException ();
 272
 273                                         return q._array [(q._size - 1 - idx + q._head) % q._array.Length];
 274                                 }
 275                         }
 276
 277                         void IEnumerator.Reset ()
 278                         {
 279                                 if (ver != q._version)
 280                                         throw new InvalidOperationException ();
 281
 282                                 idx = NOT_STARTED;
 283                         }
 284
 285                         object IEnumerator.Current {
 286                                 get { return Current; }
 287                         }
 288
 289                 }
 290         }
 291 }