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                 public Queue ()
  53                 {
  54                         _array = new T [0];
  55                 }
  56
  57                 public Queue (int count)
  58                 {
  59                         if (count < 0)
  60                                 throw new ArgumentOutOfRangeException ("count");
  61
  62                         _array = new T [count];
  63                 }
  64
  65                 public Queue (IEnumerable <T> collection)
  66                 {
  67                         if (collection == null)
  68                                 throw new ArgumentNullException ("collection");
  69
  70                         var icoll = collection as ICollection<T>;
  71                         var size = icoll != null ? icoll.Count : 0;
  72
  73                         _array = new T [size];
  74
  75                         foreach (T t in collection)
  76                                 Enqueue (t);
  77                 }
  78
  79                 public void Clear ()
  80                 {
  81                         Array.Clear (_array, 0, _array.Length);
  82
  83                         _head = _tail = _size = 0;
  84                         _version++;
  85                 }
  86
  87                 public bool Contains (T item)
  88                 {
  89                         if (item == null) {
  90                                 foreach (T t in this)
  91                                         if (t == null)
  92                                                 return true;
  93                         } else {
  94                                 foreach (T t in this)
  95                                         if (item.Equals (t))
  96                                                 return true;
  97                         }
  98
  99                         return false;
 100                 }
 101
 102                 public void CopyTo (T [] array, int idx)
 103                 {
 104                         if (array == null)
 105                                 throw new ArgumentNullException ();
 106
 107                         ((ICollection) this).CopyTo (array, idx);
 108                 }
 109
 110                 void ICollection.CopyTo (Array array, int idx)
 111                 {
 112                         if (array == null)
 113                                 throw new ArgumentNullException ();
 114
 115                         if ((uint) idx > (uint) array.Length)
 116                                 throw new ArgumentOutOfRangeException ();
 117
 118                         if (array.Length - idx < _size)
 119                                 throw new ArgumentOutOfRangeException ();
 120
 121                         if (_size == 0)
 122                                 return;
 123
 124                         try {
 125                                 int contents_length = _array.Length;
 126                                 int length_from_head = contents_length - _head;
 127
 128                                 Array.Copy (_array, _head, array, idx, Math.Min (_size, length_from_head));
 129                                 if (_size > length_from_head)
 130                                         Array.Copy (_array, 0, array,
 131                                                     idx  + length_from_head,
 132                                                     _size - length_from_head);
 133                         } catch (ArrayTypeMismatchException) {
 134                                 throw new ArgumentException ();
 135                         }
 136                 }
 137
 138                 public T Dequeue ()
 139                 {
 140                         T ret = Peek ();
 141
 142                         // clear stuff out to make the GC happy
 143                         _array [_head] = default (T);
 144
 145                         if (++_head == _array.Length)
 146                                 _head = 0;
 147                         _size --;
 148                         _version ++;
 149
 150                         return ret;
 151                 }
 152
 153                 public T Peek ()
 154                 {
 155                         if (_size == 0)
 156                                 throw new InvalidOperationException ();
 157
 158                         return _array [_head];
 159                 }
 160
 161                 public void Enqueue (T item)
 162                 {
 163                         if (_size == _array.Length || _tail == _array.Length)
 164                                 SetCapacity (Math.Max (Math.Max (_size, _tail) * 2, 4));
 165
 166                         _array [_tail] = item;
 167
 168                         if (++_tail == _array.Length)
 169                                 _tail = 0;
 170
 171                         _size ++;
 172                         _version ++;
 173                 }
 174
 175                 public T [] ToArray ()
 176                 {
 177                         T [] t = new T [_size];
 178                         CopyTo (t, 0);
 179                         return t;
 180                 }
 181
 182                 public void TrimExcess ()
 183                 {
 184                         if (_size < _array.Length * 0.9)
 185                                 SetCapacity (_size);
 186                 }
 187
 188                 void SetCapacity (int new_size)
 189                 {
 190                         if (new_size == _array.Length)
 191                                 return;
 192
 193                         if (new_size < _size)
 194                                 throw new InvalidOperationException ("shouldnt happen");
 195
 196                         T [] new_data = new T [new_size];
 197                         if (_size > 0)
 198                                 CopyTo (new_data, 0);
 199
 200                         _array = new_data;
 201                         _tail = _size;
 202                         _head = 0;
 203                         _version ++;
 204                 }
 205
 206                 public int Count {
 207                         get { return _size; }
 208                 }
 209
 210                 bool ICollection.IsSynchronized {
 211                         get { return false; }
 212                 }
 213
 214                 object ICollection.SyncRoot {
 215                         get { return this; }
 216                 }
 217
 218                 public Enumerator GetEnumerator ()
 219                 {
 220                         return new Enumerator (this);
 221                 }
 222
 223                 IEnumerator <T> IEnumerable<T>.GetEnumerator ()
 224                 {
 225                         return GetEnumerator ();
 226                 }
 227
 228                 IEnumerator IEnumerable.GetEnumerator ()
 229                 {
 230                         return GetEnumerator ();
 231                 }
 232
 233                 [Serializable]
 234                 public struct Enumerator : IEnumerator <T>, IEnumerator, IDisposable {
 235                         const int NOT_STARTED = -2;
 236
 237                         // this MUST be -1, because we depend on it in move next.
 238                         // we just decr the _size, so, 0 - 1 == FINISHED
 239                         const int FINISHED = -1;
 240
 241                         Queue <T> q;
 242                         int idx;
 243                         int ver;
 244
 245                         internal Enumerator (Queue <T> q)
 246                         {
 247                                 this.q = q;
 248                                 idx = NOT_STARTED;
 249                                 ver = q._version;
 250                         }
 251
 252                         // for some fucked up reason, MSFT added a useless dispose to this class
 253                         // It means that in foreach, we must still do a try/finally. Broken, very
 254                         // broken.
 255                         public void Dispose ()
 256                         {
 257                                 idx = NOT_STARTED;
 258                         }
 259
 260                         public bool MoveNext ()
 261                         {
 262                                 if (ver != q._version)
 263                                         throw new InvalidOperationException ();
 264
 265                                 if (idx == NOT_STARTED)
 266                                         idx = q._size;
 267
 268                                 return idx != FINISHED && -- idx != FINISHED;
 269                         }
 270
 271                         public T Current {
 272                                 get {
 273                                         if (idx < 0)
 274                                                 throw new InvalidOperationException ();
 275
 276                                         return q._array [(q._size - 1 - idx + q._head) % q._array.Length];
 277                                 }
 278                         }
 279
 280                         void IEnumerator.Reset ()
 281                         {
 282                                 if (ver != q._version)
 283                                         throw new InvalidOperationException ();
 284
 285                                 idx = NOT_STARTED;
 286                         }
 287
 288                         object IEnumerator.Current {
 289                                 get { return Current; }
 290                         }
 291
 292                 }
 293         }
 294 }