Introduce SafeIDispatchWrapper class to simplify the management of COM interfaces for where we do not want to define a full SafeComWrapper

Clean up the messy implementation in AccessApp and use SafeIDispatchWrapper
Split HostDocument and its associated objects into its own file

Author: bclothier

Rubberduck.Core/Navigation/CodeExplorer/CodeExplorerComponentViewModel.cs

@@ -70,8 +70,8 @@ public CodeExplorerComponentViewModel(CodeExplorerItemViewModel parent, Declarat
                     case ComponentType.Document:
                         string parenthesizedName;
                         using (var app = _vbe.HostApplication())
-                        using (var document = app.GetDocument(qualifiedModuleName))
                         {
+                            var document = app.GetDocument(qualifiedModuleName);
                             parenthesizedName = document.Name ?? string.Empty;
                         }
 

Rubberduck.VBEEditor/SafeComWrappers/Abstract/HostApplicationBase.cs

@@ -142,9 +142,9 @@ private static IProperty ApplicationPropertyFromDocumentModule(IVBE vbe)
 
         public string ApplicationName { get; }
 
-        public virtual IEnumerable<IHostDocument> GetDocuments() => null;
+        public virtual IEnumerable<HostDocument> GetDocuments() => null;
 
-        public virtual IHostDocument GetDocument(QualifiedModuleName moduleName) => null;
+        public virtual HostDocument GetDocument(QualifiedModuleName moduleName) => null;
 
         public override bool Equals(ISafeComWrapper<TApplication> other)
         {

Rubberduck.VBEEditor/SafeComWrappers/SafeIDispatchWrapper.cs

@@ -4,6 +4,14 @@
 
 namespace Rubberduck.VBEditor.SafeComWrappers
 {
+    public class SafeIDispatchWrapper<TDispatch> : SafeIDispatchWrapper
+    {
+        public SafeIDispatchWrapper(TDispatch target, bool rewrapping = false) : base(target, rewrapping)
+        { }
+
+        public new TDispatch Target => (TDispatch) base.Target;
+    }
+
     public class SafeIDispatchWrapper : SafeComWrapper<dynamic>
     {
         public SafeIDispatchWrapper(object target, bool rewrapping = false) : base(target, rewrapping)

Rubberduck.VBEEditor/SafeComWrappers/VB/Abstract/HostDocument.cs

@@ -0,0 +1,78 @@
+using System;
+
+namespace Rubberduck.VBEditor.SafeComWrappers.Abstract
+{
+    /// <summary>
+    /// Provides a generic manner of reporting document state for use within Rubberduck
+    /// </summary>
+    /// <remarks>
+    /// Different hosts may have different states and they may behave differently. For example,
+    /// Excel's Worksheet document has no true design-time state; only time it is locked is when
+    /// the focus is inside the formula box in the Excel UI. On the other hand, Access has both
+    /// a design time and a run time state for its Form document and Report document. The enum
+    /// is meant to provide a generic representation and must correspond exactly to how the host
+    /// will treat the document. All hosts need not implement the full set of the enum but must
+    /// represent it exactly as per the description of the enum member.
+    /// </remarks>
+    public enum DocumentState
+    {
+        /// <summary>
+        /// The document is not open and its accompanying <see cref="IVBComponent"/> is not available.
+        /// </summary>
+        Closed,
+        /// <summary>
+        /// The document is open in design mode.
+        /// </summary>
+        DesignView,
+        /// <summary>
+        /// The document is open in non-design mode. Not all design-time operations are available.
+        /// </summary>
+        ActiveView
+    }
+
+    public interface IHostDocument
+    {
+        string Name { get; }
+        string ClassName { get; }
+        DocumentState State { get; }
+        bool TryGetTarget(out SafeIDispatchWrapper iDispatch);
+    }
+
+    public class HostDocument : IHostDocument
+    {
+        private readonly Func<SafeIDispatchWrapper> _getTargetFunc;
+
+        public HostDocument(string name, string className, DocumentState state, Func<SafeIDispatchWrapper> getTargetFunc)
+        {
+            Name = name;
+            ClassName = className;
+            State = state;
+
+            _getTargetFunc = getTargetFunc;
+        }
+
+        public string Name { get; }
+        public string ClassName { get; }
+        public DocumentState State { get; }
+
+        public bool TryGetTarget(out SafeIDispatchWrapper iDispatch)
+        {
+            if (_getTargetFunc == null)
+            {
+                iDispatch = null;
+                return false;
+            }
+
+            try
+            {
+                iDispatch = _getTargetFunc.Invoke();
+                return true;
+            }
+            catch
+            {
+                iDispatch = null;
+                return false;
+            }
+        }
+    }
+}

Rubberduck.VBEEditor/SafeComWrappers/VB/Abstract/IHostApplication.cs

@@ -1,7 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.ComponentModel;
-using System.Runtime.InteropServices;
 
 namespace Rubberduck.VBEditor.SafeComWrappers.Abstract
 {
@@ -25,70 +23,14 @@ public interface IHostApplication : IDisposable
         /// with using those properties when the document is not in a design mode. For
         /// that reason, it's better to get the data using host's object model instead.
         /// </remarks>
-        IEnumerable<IHostDocument> GetDocuments();
+        IEnumerable<HostDocument> GetDocuments();
 
         /// <summary>
         /// Gets data for a host-specific document not otherwise exposed via VBIDE API
         /// </summary>
         /// <param name="moduleName"><see cref="QualifiedModuleName"/> representing a VBComponent object</param>
-        /// <returns><see cref="IHostDocument"/> data</returns>
+        /// <returns><see cref="HostDocument"/> data</returns>
         /// <inheritdoc cref="GetDocuments"/>
-        IHostDocument GetDocument(QualifiedModuleName moduleName);
-    }
-
-    public enum DocumentState
-    {
-        /// <summary>
-        /// The document is not open and its accompanying <see cref="IVBComponent"/> may not be available.
-        /// </summary>
-        Closed,
-        /// <summary>
-        /// The document is open in design mode.
-        /// </summary>
-        DesignView,
-        /// <summary>
-        /// The document is open in non-design mode. It may not be safe to parse the document in this state.
-        /// </summary>
-        ActiveView
-    }
-
-    public interface IHostDocument
-    {
-        string Name { get; }
-        string ClassName { get; }
-        DocumentState State { get; }
-        bool TryGetTarget(out SafeIDispatchWrapper iDispatch)
-    }
-
-    public class HostDocument : IHostDocument
-    {
-        private readonly Func<SafeIDispatchWrapper> _getTargetFunc;
-
-        public HostDocument(string name, string className, DocumentState state, Func<SafeIDispatchWrapper> getTargetFunc)
-        {
-            Name = name;
-            ClassName = className;
-            State = state;
-
-            _getTargetFunc = getTargetFunc;
-        }
-
-        public string Name { get; }
-        public string ClassName { get; }
-        public DocumentState State { get; }
-
-        public bool TryGetTarget(out SafeIDispatchWrapper iDispatch)
-        {
-            try
-            {
-                iDispatch = _getTargetFunc.Invoke();
-                return true;
-            }
-            catch
-            {
-                iDispatch = null;
-                return false;
-            }
-        }
+        HostDocument GetDocument(QualifiedModuleName moduleName);
     }
 }

Rubberduck.VBEditor.VBA/SafeComWrappers/Application/AccessApp.cs

@@ -1,6 +1,4 @@
-using System;
 using System.Collections.Generic;
-using System.Runtime.InteropServices;
 using Microsoft.Office.Interop.Access;
 using Rubberduck.VBEditor.SafeComWrappers.Abstract;
 
@@ -11,117 +9,73 @@ public class AccessApp : HostApplicationBase<Microsoft.Office.Interop.Access.App
     {
         public AccessApp() : base("Access") { }
 
-        public override IHostDocument GetDocument(QualifiedModuleName moduleName)
+        public override HostDocument GetDocument(QualifiedModuleName moduleName)
         {
             if (moduleName.ComponentName.StartsWith("Form_"))
             {
                 var name = moduleName.ComponentName.Substring("Form_".Length);
-                _CurrentProject currentProject = null;
-                AllObjects allForms = null;
-                AccessObject accessObject = null;
-                Forms forms = null;
-                try
-                {
-                    currentProject = Application.CurrentProject;
-                    forms = Application.Forms;
-                    allForms = currentProject.AllForms;
-                    accessObject = allForms[name];
-
+                using (var currentProject = new SafeIDispatchWrapper<_CurrentProject>(Application.CurrentProject))
+                using (var allForms = new SafeIDispatchWrapper<AllObjects>(currentProject.Target.AllForms))
+                using (var forms = new SafeIDispatchWrapper<Forms>(Application.Forms))
+                using (var accessObject = new SafeIDispatchWrapper<AccessObject>(allForms.Target[name]))
+                { 
                     return LoadHostDocument("Access.Form", accessObject, forms);
                 }
-                finally
-                {
-                    if (forms != null) Marshal.ReleaseComObject(forms);
-                    if (accessObject != null) Marshal.ReleaseComObject(accessObject);
-                    if (allForms != null) Marshal.ReleaseComObject(allForms);
-                    if (currentProject != null) Marshal.ReleaseComObject(currentProject);
-                }
             }
 
             if (moduleName.ComponentName.StartsWith("Report_"))
             {
                 var name = moduleName.ComponentName.Substring("Report_".Length);
-                _CurrentProject currentProject = null;
-                AllObjects allForms = null;
-                AccessObject accessObject = null;
-                Reports reports = null;
-                try
+                using (var currentProject = new SafeIDispatchWrapper<_CurrentProject>(Application.CurrentProject))
+                using (var allReports = new SafeIDispatchWrapper<AllObjects>(currentProject.Target.AllReports))
+                using (var reports = new SafeIDispatchWrapper<Reports>(Application.Reports))
+                using (var accessObject = new SafeIDispatchWrapper<AccessObject>(allReports.Target[name]))
                 {
-                    currentProject = Application.CurrentProject;
-                    reports = Application.Reports;
-                    allForms = currentProject.AllForms;
-                    accessObject = allForms[name];
-
                     return LoadHostDocument("Access.Report", accessObject, reports);
                 }
-                finally
-                {
-                    if (reports != null) Marshal.ReleaseComObject(reports);
-                    if (accessObject != null) Marshal.ReleaseComObject(accessObject);
-                    if (allForms != null) Marshal.ReleaseComObject(allForms);
-                    if (currentProject != null) Marshal.ReleaseComObject(currentProject);
-                }
             }
 
             return null;
         }
 
-        public override IEnumerable<IHostDocument> GetDocuments()
+        public override IEnumerable<HostDocument> GetDocuments()
         {
             var result = new List<HostDocument>();
-            _CurrentProject currentProject = null;
-            AllObjects allObjects = null;
-            Forms forms = null;
-            Reports reports = null;
-
-            try
+            using (var currentProject = new SafeIDispatchWrapper<_CurrentProject>(Application.CurrentProject))
+            using (var allForms = new SafeIDispatchWrapper<AllObjects>(currentProject.Target.AllForms))
+            using (var allReports = new SafeIDispatchWrapper<AllObjects>(currentProject.Target.AllReports))
+            using (var forms = new SafeIDispatchWrapper<Forms>(Application.Forms))
+            using (var reports = new SafeIDispatchWrapper<Reports>(Application.Reports))
             {
-                currentProject = Application.CurrentProject;
-                allObjects = currentProject.AllForms;
-                forms = Application.Forms;
-
-                PopulateList(ref result, "Access.Form", allObjects, forms);
-
-                Marshal.ReleaseComObject(allObjects);
-
-                allObjects = currentProject.AllReports;
-                reports = Application.Reports;
-
-                PopulateList(ref result, "Access.Report", allObjects, reports);
+                PopulateList(ref result, "Access.Form", allForms, forms);
+                PopulateList(ref result, "Access.Report", allReports, reports);
             }
-            finally
-            {
-                if (allObjects != null) Marshal.ReleaseComObject(allObjects);
-                if (forms != null) Marshal.ReleaseComObject(forms);
-                if (reports != null) Marshal.ReleaseComObject(reports);
-                if (currentProject != null) Marshal.ReleaseComObject(currentProject);
-            }
-            
+
             return result;
         }
 
-        private void PopulateList(ref List<HostDocument> result, string className, AllObjects allObjects, dynamic objects)
+        private void PopulateList(ref List<HostDocument> result, string className, SafeIDispatchWrapper<AllObjects> allObjects, dynamic objects)
         {
-            foreach (AccessObject accessObject in allObjects)
+            foreach (AccessObject rawAccessObject in allObjects.Target)
+            using (var accessObject = new SafeIDispatchWrapper<AccessObject>(rawAccessObject))
             {
                 var item = LoadHostDocument(className, accessObject, objects);
                 result.Add(item);
             }
         }
 
-        private HostDocument LoadHostDocument(string className, AccessObject accessObject, dynamic objects)
+        private HostDocument LoadHostDocument(string className, SafeIDispatchWrapper<AccessObject> accessObject, dynamic objects)
         {
             var state = DocumentState.Closed;
-            if (!accessObject.IsLoaded)
+            if (!accessObject.Target.IsLoaded)
             {
-                return new HostDocument(accessObject.Name, className, null, state);
+                return new HostDocument(accessObject.Target.Name, className, state, null);
             }
 
-            object target = objects[accessObject.Name];
-            state = accessObject.CurrentView == AcCurrentView.acCurViewDesign
+            state = accessObject.Target.CurrentView == AcCurrentView.acCurViewDesign
                 ? DocumentState.DesignView
                 : DocumentState.ActiveView;
-            return new HostDocument(accessObject.Name, className, target, state);
+            return new HostDocument(accessObject.Target.Name, className, state, null);
         }
     }
 }

Rubberduck.VBEditor.VBA/SafeComWrappers/Application/FallbackApp.cs

@@ -10,8 +10,8 @@ public FallbackApp(IVBE vbe)
         { }
 
         public string ApplicationName => "(unknown)";
-        public IEnumerable<IHostDocument> GetDocuments() => null;
-        public IHostDocument GetDocument(QualifiedModuleName moduleName) => null;
+        public IEnumerable<HostDocument> GetDocuments() => null;
+        public HostDocument GetDocument(QualifiedModuleName moduleName) => null;
         public void Dispose() { }
     }
 }