developer/VSSDK/Samples/Code_Sweep/C#/VsPackage/TaskEnumerator.cs

   1 /***************************************************************************
   2
   3 Copyright (c) Microsoft Corporation. All rights reserved.
   4 THIS CODE IS PROVIDED *AS IS* WITHOUT WARRANTY OF
   5 ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING ANY
   6 IMPLIED WARRANTIES OF FITNESS FOR A PARTICULAR
   7 PURPOSE, MERCHANTABILITY, OR NON-INFRINGEMENT.
   8
   9 ***************************************************************************/
  10
  11 using Microsoft.VisualStudio;
  12 using Microsoft.VisualStudio.Shell.Interop;
  13 using System.Collections.Generic;
  14
  15 namespace Microsoft.Samples.VisualStudio.CodeSweep.VSPackage
  16 {
  17     class TaskEnumerator : IVsEnumTaskItems
  18     {
  19         /// <summary>
  20         /// Creates a new task enumerator.
  21         /// </summary>
  22         /// <param name="items">The items this enumerator will enumerate.</param>
  23         /// <param name="showIgnored">Determines whether tasks for which Ignored==true will be skipped.</param>
  24         /// <exception cref="System.ArgumentNullException">Thrown if <c>items</c> is null.</exception>
  25         /// <remarks>
  26         /// This enumerator operates on a copy of the contents of <c>items</c>, so if <c>items</c>
  27         /// is changed after this call, it will not affect the results.
  28         /// </remarks>
  29         public TaskEnumerator(IEnumerable<Task> items, bool showIgnored)
  30         {
  31             _showIgnored = showIgnored;
  32             _items = new List<Task>(items);
  33         }
  34
  35         #region IVsEnumTaskItems Members
  36
  37         /// <summary>
  38         /// Creates a new enumerator with identical content to this one.
  39         /// </summary>
  40         /// <param name="ppenum">The newly created enumerator.</param>
  41         /// <returns>An HRESULT indicating the success of the operation.</returns>
  42         public int Clone(out IVsEnumTaskItems ppenum)
  43         {
  44             ppenum = new TaskEnumerator(_items, _showIgnored);
  45             return VSConstants.S_OK;
  46         }
  47
  48         /// <summary>
  49         /// Enumerates a requested number of items.
  50         /// </summary>
  51         /// <param name="celt">The number of items to return.</param>
  52         /// <param name="rgelt">The array of items that will be returned.</param>
  53         /// <param name="pceltFetched">The array whose first element will be set to the actual number of items returned.</param>
  54         /// <returns>S_OK if all requested items were returned; S_FALSE if fewer were available; E_INVALIDARG if <c>celt</c> is less than zero, <c>rgelt</c> is null, or <c>pceltFetched</c> is null.</returns>
  55         /// <remarks>
  56         /// This method returns failure codes instead of throwing exceptions because it is intended to be called from native code.
  57         /// If the task provider's IsShowingIgnoredInstances property is false, ignored instances will be skipped.
  58         /// </remarks>
  59         public int Next(uint celt, IVsTaskItem[] rgelt, uint[] pceltFetched)
  60         {
  61             pceltFetched[0] = 0;
  62
  63             while (pceltFetched[0] < celt && _next < _items.Count)
  64             {
  65                 if (_showIgnored || !_items[_next].Ignored)
  66                 {
  67                     rgelt[pceltFetched[0]] = _items[_next];
  68                     pceltFetched[0]++;
  69                 }
  70                 ++_next;
  71             }
  72
  73             if (pceltFetched[0] == celt)
  74             {
  75                 return VSConstants.S_OK;
  76             }
  77             else
  78             {
  79                 return VSConstants.S_FALSE;
  80             }
  81         }
  82
  83         /// <summary>
  84         /// Resets the enumerator so that the next call to <c>Next</c> will begin at the first element.
  85         /// </summary>
  86         /// <returns>S_OK</returns>
  87         public int Reset()
  88         {
  89             _next = 0;
  90             return VSConstants.S_OK;
  91         }
  92
  93         /// <summary>
  94         /// Skips a specified number of items
  95         /// </summary>
  96         /// <param name="celt">The number of items to skip.</param>
  97         /// <returns>S_OK if the requested number of items was skipped; S_FALSE if <c>celt</c> is larger than the number of available items; E_INVALIDARG if <c>celt</c> is less than zero.</returns>
  98         /// <remarks>
  99         /// This method returns failure codes instead of throwing exceptions because it is intended to be called from native code.
 100         /// If the task provider's IsShowingIgnoredInstances property is false, ignored instances will not be counted.
 101         /// </remarks>
 102         public int Skip(uint celt)
 103         {
 104             IVsTaskItem[] items = new IVsTaskItem[celt];
 105             uint[] fetched = new uint[] { 0 };
 106
 107             return Next(celt, items, fetched);
 108         }
 109
 110         #endregion IVsEnumTaskItems Members
 111
 112         #region Private Members
 113
 114         readonly List<Task> _items;
 115         int _next = 0;
 116         readonly bool _showIgnored;
 117
 118         #endregion Private Members
 119     }
 120 }