src/Boo.Lang/GenericGeneratorEnumerator.cs

   1 #region license
   2 // Copyright (c) 2004, Rodrigo B. de Oliveira (rbo@acm.org)
   3 // All rights reserved.
   4 //
   5 // Redistribution and use in source and binary forms, with or without modification,
   6 // are permitted provided that the following conditions are met:
   7 //
   8 //     * Redistributions of source code must retain the above copyright notice,
   9 //     this list of conditions and the following disclaimer.
  10 //     * Redistributions in binary form must reproduce the above copyright notice,
  11 //     this list of conditions and the following disclaimer in the documentation
  12 //     and/or other materials provided with the distribution.
  13 //     * Neither the name of Rodrigo B. de Oliveira nor the names of its
  14 //     contributors may be used to endorse or promote products derived from this
  15 //     software without specific prior written permission.
  16 //
  17 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
  18 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  19 // WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  20 // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
  21 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  23 // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  24 // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  25 // OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26 // THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27 #endregion
  28
  29 namespace Boo.Lang
  30 {
  31         using System;
  32         using System.Collections;
  33         using System.Collections.Generic;
  34
  35         public abstract class GenericGeneratorEnumerator<T> : IEnumerator<T>
  36         {
  37                 protected T _current;
  38
  39                 // HACK: _state should be protected, not public.
  40                 // Marked public because of a bug in Mono. See BOO-796 and
  41                 // http://lists.ximian.com/pipermail/mono-devel-list/2007-February/022431.html
  42                 public int _state;
  43
  44                 public GenericGeneratorEnumerator()
  45                 {
  46                         _state = 0;
  47                 }
  48
  49                 public T Current
  50                 {
  51                         get
  52                         {
  53                                 return _current;
  54                         }
  55                 }
  56
  57                 object IEnumerator.Current
  58                 {
  59                         get { return _current; }
  60                 }
  61
  62                 public virtual void Dispose()
  63                 {
  64                 }
  65
  66                 public void Reset()
  67                 {
  68                         // We cannot reset the local variables of the generator method,
  69                         // so let's do it like C# and throw a NotSupportedException
  70                         throw new NotSupportedException();
  71                 }
  72
  73                 public abstract bool MoveNext();
  74
  75                 protected bool Yield(int state, T value)
  76                 {
  77                         _state = state;
  78                         _current = value;
  79                         return true;
  80                 }
  81         }
  82 }