Merge pull request #3811 from MDoerner/IntroducingDisposalActionContainer

DisposalActionContainer (no user-facing changes)

Author: retailcoder

Rubberduck.VBEEditor/Rubberduck.VBEditor.csproj

@@ -262,6 +262,7 @@
     <Compile Include="SafeComWrappers\MSForms\WindowState.cs" />
     <Compile Include="SafeComWrappers\SafeComWrapper.cs" />
     <Compile Include="SafeComWrappers\VBA\VBE.cs" />
+    <Compile Include="Utility\DisposalActionContainer.cs" />
     <Compile Include="WindowsApi\ChildWindowFinder.cs" />
     <Compile Include="WindowsApi\CodePaneSubclass.cs" />
     <Compile Include="WindowsApi\DesignerWindowSubclass.cs" />

Rubberduck.VBEEditor/Utility/DisposalActionContainer.cs

@@ -0,0 +1,45 @@
+using System;
+
+namespace Rubberduck.VBEditor.Utility
+{
+    public interface IDisposalActionContainer<out T>: IDisposable
+    {
+        T Value { get; }
+    }
+
+    internal sealed class DisposalActionContainer<T> : IDisposalActionContainer<T>
+    {
+        public T Value { get; }
+        private readonly Action _disposalAction;
+
+        public DisposalActionContainer(T value, Action disposalAction)
+        {
+            Value = value;
+            _disposalAction = disposalAction;
+        }
+
+        private bool _isDisposed = false;
+        private readonly object _disposalLockObject = new object();
+        public void Dispose()
+        {
+            lock (_disposalLockObject)
+            {
+                if (_isDisposed)
+                {
+                    return;
+                }
+                _isDisposed = true;
+            }
+
+            _disposalAction.Invoke();
+        }
+    }
+
+    public static class DisposalActionContainer
+    {
+        public static IDisposalActionContainer<T> Create<T>(T value, Action disposalAction)
+        {
+            return new DisposalActionContainer<T>(value, disposalAction);
+        }
+    }
+}

RubberduckTests/RubberduckTests.csproj

@@ -108,6 +108,7 @@
     <Compile Include="Mocks\MockExtentions.cs" />
     <Compile Include="Inspections\DefTypeStatementInspectionTests.cs" />
     <Compile Include="Inspections\InspectionProviderTests.cs" />
+    <Compile Include="VBEditor\Utility\DisposalActionContainerTests.cs" />
     <Compile Include="VBEditor\ComSafeManagerTests.cs" />
     <Compile Include="VBEditor\ProjectsRepositoryTests.cs" />
     <Compile Include="VBEditor\ReferenceEqualityComparerTests.cs" />
@@ -346,7 +347,9 @@
       <Name>Rubberduck.VBEditor</Name>
     </ProjectReference>
   </ItemGroup>
-  <ItemGroup />
+  <ItemGroup>
+    <Folder Include="Utility\" />
+  </ItemGroup>
   <ItemGroup>
     <None Include="IntegrationTests\FakeTests.bas" />
     <None Include="IntegrationTests\StubTests.bas" />

RubberduckTests/VBEditor/Utility/DisposalActionContainerTests.cs

@@ -0,0 +1,46 @@
+using NUnit.Framework;
+using Rubberduck.VBEditor.Utility;
+
+namespace RubberduckTests.VBEditor.Utility
+{
+    [TestFixture()]
+    public class DisposalActionContainerTests
+    {
+        [Test()]
+        public void ValueReturnsValuePassedIn()
+        {
+            var testValue = 42;
+            var dac = DisposalActionContainer.Create(testValue, () => { });
+            var returnedValue = dac.Value;
+
+            Assert.AreEqual(testValue, returnedValue);
+        }
+
+        [Test()]
+        public void FirstDisposeTriggersActionPassedIn()
+        {
+            var useCount = 0;
+            var dac = DisposalActionContainer.Create(42, () => useCount++);
+            dac.Dispose();
+            var expectedUseCount = 1;
+
+            Assert.AreEqual(expectedUseCount, useCount);
+        }
+
+        [Test()]
+        public void MultipleCallsOfDisposeTriggerTheActionPassedInOnce()
+        {
+            var useCount = 0;
+            var dac = DisposalActionContainer.Create(42, () => useCount++);
+            dac.Dispose();
+            dac.Dispose();
+            dac.Dispose();
+            dac.Dispose();
+            dac.Dispose();
+            dac.Dispose();
+            var expectedUseCount = 1;
+
+            Assert.AreEqual(expectedUseCount, useCount);
+        }
+    }
+}