First attempt at document model.

src/AddIns/Analysis/UnitTesting/NUnit/NUnitTestClass.cs

@@ -4,9 +4,12 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+
 using ICSharpCode.NRefactory.TypeSystem;
 using ICSharpCode.NRefactory.TypeSystem.Implementation;
 using ICSharpCode.SharpDevelop;
+using ICSharpCode.SharpDevelop.Dom;
+using ICSharpCode.SharpDevelop.Parser;
 using ICSharpCode.SharpDevelop.Widgets;
 
 namespace ICSharpCode.UnitTesting
@@ -67,7 +70,12 @@ namespace ICSharpCode.UnitTesting
 		
 		public ITypeDefinition Resolve()
 		{
-			ICompilation compilation = SD.ParserService.GetCompilation(parentProject.Project);
+			return Resolve(SD.ParserService.GetCurrentSolutionSnapshot());
+		}
+		
+		public ITypeDefinition Resolve(ISolutionSnapshotWithProjectMapping solutionSnapshot)
+		{
+			ICompilation compilation = solutionSnapshot.GetCompilation(parentProject.Project);
 			IType type = compilation.MainAssembly.GetTypeDefinition(fullTypeName);
 			return type.GetDefinition();
 		}

src/AddIns/Analysis/UnitTesting/NUnit/NUnitTestMethod.cs

@@ -5,6 +5,7 @@ using System;
 using System.Windows.Input;
 using ICSharpCode.NRefactory.TypeSystem;
 using ICSharpCode.SharpDevelop;
+using ICSharpCode.SharpDevelop.Parser;
 using ICSharpCode.SharpDevelop.Widgets;
 
 namespace ICSharpCode.UnitTesting
@@ -80,7 +81,12 @@ namespace ICSharpCode.UnitTesting
 		
 		public IMethod Resolve()
 		{
-			ICompilation compilation = SD.ParserService.GetCompilation(parentProject.Project);
+			return Resolve(SD.ParserService.GetCurrentSolutionSnapshot());
+		}
+		
+		public IMethod Resolve(ISolutionSnapshotWithProjectMapping solutionSnapshot)
+		{
+			ICompilation compilation = solutionSnapshot.GetCompilation(parentProject.Project);
 			IMethod resolvedMethod = method.Resolve(new SimpleTypeResolveContext(compilation.MainAssembly));
 			return resolvedMethod;
 		}

src/Main/Base/Project/Dom/ConcatModelCollection.cs

@@ -0,0 +1,164 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Collections.Specialized;
+using System.Linq;
+
+namespace ICSharpCode.SharpDevelop.Dom
+{
+	/// <summary>
+	/// A <see cref="IModelCollection{T}"/> that works by concatening multiple
+	/// other model collections.
+	/// </summary>
+	public sealed class ConcatModelCollection<T> : IModelCollection<T>
+	{
+		sealed class InputCollection : Collection<IModelCollection<T>>
+		{
+			readonly ConcatModelCollection<T> owner;
+			
+			public InputCollection(ConcatModelCollection<T> owner)
+			{
+				this.owner = owner;
+			}
+			
+			protected override void ClearItems()
+			{
+				if (owner.collectionChanged != null) {
+					foreach (var input in Items) {
+						input.CollectionChanged -= owner.OnInputCollectionChanged;
+					}
+				}
+				base.ClearItems();
+				owner.RaiseCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
+			}
+			
+			protected override void InsertItem(int index, IModelCollection<T> item)
+			{
+				if (owner.collectionChanged != null)
+					item.CollectionChanged += owner.OnInputCollectionChanged;
+				base.InsertItem(index, item);
+				owner.RaiseCollectionChanged(new NotifyCollectionChangedEventArgs(
+					NotifyCollectionChangedAction.Add, item.ToArray(), owner.GetCount(index)));
+			}
+			
+			protected override void RemoveItem(int index)
+			{
+				if (owner.collectionChanged != null)
+					Items[index].CollectionChanged -= owner.OnInputCollectionChanged;
+				var oldItems = Items[index].ToArray();
+				base.RemoveItem(index);
+				owner.RaiseCollectionChanged(new NotifyCollectionChangedEventArgs(
+					NotifyCollectionChangedAction.Remove, oldItems, owner.GetCount(index)));
+			}
+			
+			protected override void SetItem(int index, IModelCollection<T> item)
+			{
+				RemoveItem(index);
+				InsertItem(index, item);
+			}
+		}
+		
+		InputCollection inputs;
+		
+		public ConcatModelCollection()
+		{
+			this.inputs = new InputCollection(this);
+		}
+		
+		public IList<IModelCollection<T>> Inputs {
+			get { return inputs; }
+		}
+		
+		NotifyCollectionChangedEventHandler collectionChanged;
+		
+		public event NotifyCollectionChangedEventHandler CollectionChanged {
+			add {
+				var oldEventHandlers = collectionChanged;
+				collectionChanged += value;
+				if (oldEventHandlers == null && collectionChanged != null) {
+					foreach (var input in inputs)
+						input.CollectionChanged += OnInputCollectionChanged;
+				}
+			}
+			remove {
+				var oldEventHandlers = collectionChanged;
+				collectionChanged -= value;
+				if (oldEventHandlers != null && collectionChanged == null) {
+					foreach (var input in inputs)
+						input.CollectionChanged -= OnInputCollectionChanged;
+				}
+			}
+		}
+		
+		void RaiseCollectionChanged(NotifyCollectionChangedEventArgs e)
+		{
+			if (collectionChanged != null)
+				collectionChanged(this, e);
+		}
+		
+		void OnInputCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
+		{
+			int inputIndex = inputs.IndexOf((IModelCollection<T>)sender);
+			int startIndex = GetCount(inputIndex);
+			NotifyCollectionChangedEventArgs newEventArgs;
+			switch (e.Action) {
+				case NotifyCollectionChangedAction.Add:
+					newEventArgs = new NotifyCollectionChangedEventArgs(e.Action, e.NewItems, startIndex + e.NewStartingIndex);
+					break;
+				case NotifyCollectionChangedAction.Remove:
+					newEventArgs = new NotifyCollectionChangedEventArgs(e.Action, e.OldItems, startIndex + e.OldStartingIndex);
+					break;
+				case NotifyCollectionChangedAction.Replace:
+					newEventArgs = new NotifyCollectionChangedEventArgs(e.Action, e.OldItems, e.NewItems, startIndex + e.OldStartingIndex);
+					break;
+				case NotifyCollectionChangedAction.Move:
+					newEventArgs = new NotifyCollectionChangedEventArgs(e.Action, e.OldItems, startIndex + e.OldStartingIndex, startIndex + e.NewStartingIndex);
+					break;
+				case NotifyCollectionChangedAction.Reset:
+					newEventArgs = new NotifyCollectionChangedEventArgs(e.Action);
+					break;
+				default:
+					throw new NotSupportedException("Invalid value for NotifyCollectionChangedAction");
+			}
+			collectionChanged(this, newEventArgs);
+		}
+		
+		public int Count {
+			get { return GetCount(inputs.Count); }
+		}
+		
+		int GetCount(int inputIndex)
+		{
+			int count = 0;
+			for (int i = 0; i < inputIndex; i++) {
+				count += inputs[i].Count;
+			}
+			return count;
+		}
+		
+		public IEnumerator<T> GetEnumerator()
+		{
+			return inputs.SelectMany(i => i).GetEnumerator();
+		}
+		
+		IEnumerator IEnumerable.GetEnumerator()
+		{
+			return GetEnumerator();
+		}
+		
+		public T this[int index] {
+			get {
+				int inputIndex = 0;
+				while (index >= inputs[inputIndex].Count) {
+					index -= inputs[inputIndex].Count;
+					inputIndex++;
+				}
+				return inputs[inputIndex][index];
+			}
+		}
+	}
+}

src/Main/Base/Project/Dom/IEntityModel.cs

@@ -0,0 +1,40 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using System.ComponentModel;
+using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.SharpDevelop.Parser;
+using ICSharpCode.SharpDevelop.Project;
+
+namespace ICSharpCode.SharpDevelop.Dom
+{
+	/// <summary>
+	/// An NRefactory entity as a model.
+	/// </summary>
+	public interface IEntityModel : INotifyPropertyChanged
+	{
+		/// <summary>
+		/// Gets the parent project that contains this entity.
+		/// May return null if the entity is not part of a project.
+		/// </summary>
+		IProject ParentProject { get; }
+		
+		/// <summary>
+		/// Gets the region where this entity is defined.
+		/// </summary>
+		DomRegion Region { get; }
+		
+		/// <summary>
+		/// Resolves the entity in the current solution snapshot.
+		/// Returns null if the entity could not be resolved.
+		/// </summary>
+		IEntity Resolve();
+		
+		/// <summary>
+		/// Resolves the entity in the specified solution snapshot.
+		/// Returns null if the entity could not be resolved.
+		/// </summary>
+		IEntity Resolve(ISolutionSnapshotWithProjectMapping solutionSnapshot);
+	}
+}

src/Main/Base/Project/Dom/IEntityModelContext.cs

@@ -0,0 +1,79 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.SharpDevelop.Parser;
+using ICSharpCode.SharpDevelop.Project;
+
+namespace ICSharpCode.SharpDevelop.Dom
+{
+	/// <summary>
+	/// The context for an entity model.
+	/// This may be a reference to a project, or a compilation provider for a single stand-alone code file.
+	/// </summary>
+	public interface IEntityModelContext
+	{
+		/// <summary>
+		/// Used for <see cref="IEntityModel.ParentProject"/>.
+		/// </summary>
+		IProject Project { get; }
+		
+		/// <summary>
+		/// Used for <see cref="IEntityModel.Resolve()"/>.
+		/// </summary>
+		/// <param name="solutionSnapshot">
+		/// The solution snapshot provided to <see cref="IEntityModel.Resolve(ISolutionSnapshotWithProjectMapping)"/>,
+		/// or null if the <see cref="IEntityModel.Resolve()"/> overload was used.
+		/// </param>
+		ICompilation GetCompilation(ISolutionSnapshotWithProjectMapping solutionSnapshot);
+		
+		/// <summary>
+		/// Returns true if part1 is considered a better candidate for the primary part than part2.
+		/// </summary>
+		bool IsBetterPart(IUnresolvedTypeDefinition part1, IUnresolvedTypeDefinition part2);
+	}
+	
+	public class ProjectEntityModelContext : IEntityModelContext
+	{
+		readonly IProject project;
+		readonly string primaryCodeFileExtension;
+		
+		public ProjectEntityModelContext(IProject project, string primaryCodeFileExtension)
+		{
+			if (project == null)
+				throw new ArgumentNullException("project");
+			this.project = project;
+			this.primaryCodeFileExtension = primaryCodeFileExtension;
+		}
+		
+		public IProject Project {
+			get { return project; }
+		}
+		
+		public ICompilation GetCompilation(ISolutionSnapshotWithProjectMapping solutionSnapshot)
+		{
+			if (solutionSnapshot != null)
+				return solutionSnapshot.GetCompilation(project);
+			else
+				return SD.ParserService.GetCompilation(project);
+		}
+		
+		public bool IsBetterPart(IUnresolvedTypeDefinition part1, IUnresolvedTypeDefinition part2)
+		{
+			IUnresolvedFile file1 = part1.UnresolvedFile;
+			IUnresolvedFile file2 = part2.UnresolvedFile;
+			if (file1 != null && file2 == null)
+				return true;
+			if (file1 == null)
+				return false;
+			bool file1HasExtension = file1.FileName.EndsWith(primaryCodeFileExtension, StringComparison.OrdinalIgnoreCase);
+			bool file2HasExtension = file2.FileName.EndsWith(primaryCodeFileExtension, StringComparison.OrdinalIgnoreCase);
+			if (file1HasExtension && !file2HasExtension)
+				return true;
+			if (!file1HasExtension && file2HasExtension)
+				return false;
+			return file1.FileName.Length < file2.FileName.Length;
+		}
+	}
+}

src/Main/Base/Project/Dom/IMemberModel.cs

@@ -0,0 +1,27 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.SharpDevelop.Parser;
+
+namespace ICSharpCode.SharpDevelop.Dom
+{
+	/// <summary>
+	/// Observable model for a member.
+	/// </summary>
+	public interface IMemberModel : IEntityModel
+	{
+		/// <summary>
+		/// Resolves the member in the current solution snapshot.
+		/// Returns null if the member could not be resolved.
+		/// </summary>
+		IMember Resolve();
+		
+		/// <summary>
+		/// Resolves the member in the specified solution snapshot.
+		/// Returns null if the member could not be resolved.
+		/// </summary>
+		IMember Resolve(ISolutionSnapshotWithProjectMapping solutionSnapshot);
+	}
+}

src/Main/Base/Project/Dom/IModelCollection.cs

@@ -10,7 +10,7 @@ namespace ICSharpCode.SharpDevelop.Dom
 	/// <summary>
 	/// A read-only collection that provides change notifications.
 	/// </summary>
-	public interface IModelCollection<out T> : IReadOnlyCollection<T>, INotifyCollectionChanged
+	public interface IModelCollection<out T> : IReadOnlyList<T>, INotifyCollectionChanged
 	{
 	}
 }

src/Main/Base/Project/Dom/IModelService.cs

@@ -0,0 +1,15 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using ICSharpCode.NRefactory.TypeSystem;
+
+namespace ICSharpCode.SharpDevelop.Dom
+{
+	/// <summary>
+	/// Service that enables lookup of model objects from NRefactory objects.
+	/// </summary>
+	public interface IModelService
+	{
+	}
+}

src/Main/Base/Project/Dom/ITypeDefinitionModel.cs

@@ -0,0 +1,31 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.SharpDevelop.Parser;
+
+namespace ICSharpCode.SharpDevelop.Dom
+{
+	/// <summary>
+	/// Observable model for a type definition.
+	/// </summary>
+	public interface ITypeDefinitionModel : IEntityModel
+	{
+		FullTypeName FullTypeName { get; }
+		IModelCollection<ITypeDefinitionModel> NestedTypes { get; }
+		IModelCollection<IMemberModel> Members { get; }
+		
+		/// <summary>
+		/// Resolves the type definition in the current solution snapshot.
+		/// Returns null if the type definition could not be resolved.
+		/// </summary>
+		new ITypeDefinition Resolve();
+		
+		/// <summary>
+		/// Resolves the type definition in the specified solution snapshot.
+		/// Returns null if the type definition could not be resolved.
+		/// </summary>
+		new ITypeDefinition Resolve(ISolutionSnapshotWithProjectMapping solutionSnapshot);
+	}
+}

src/Main/Base/Project/Dom/ITypeDefinitionModelCollection.cs

@@ -0,0 +1,69 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using System.Collections;
+using System.Collections.ObjectModel;
+using System.Collections.Generic;
+using System.Collections.Specialized;
+using System.Linq;
+using ICSharpCode.NRefactory.TypeSystem;
+
+namespace ICSharpCode.SharpDevelop.Dom
+{
+	/// <summary>
+	/// A collection of type definition models with the ability to look them up by name.
+	/// </summary>
+	public interface ITypeDefinitionModelCollection : IModelCollection<ITypeDefinitionModel>
+	{
+		/// <summary>
+		/// Gets the type definition model with the specified type name.
+		/// Returns null if no such model object exists.
+		/// </summary>
+		ITypeDefinitionModel this[FullTypeName fullTypeName] { get; }
+		
+		/// <summary>
+		/// Gets the type definition model with the specified type name.
+		/// Returns null if no such model object exists.
+		/// </summary>
+		ITypeDefinitionModel this[TopLevelTypeName topLevelTypeName] { get; }
+	}
+	
+	public sealed class EmptyTypeDefinitionModelCollection : ITypeDefinitionModelCollection
+	{
+		public static readonly EmptyTypeDefinitionModelCollection Instance = new EmptyTypeDefinitionModelCollection();
+		
+		event NotifyCollectionChangedEventHandler INotifyCollectionChanged.CollectionChanged {
+			add { }
+			remove { }
+		}
+		
+		ITypeDefinitionModel ITypeDefinitionModelCollection.this[FullTypeName name] {
+			get { return null; }
+		}
+		
+		ITypeDefinitionModel ITypeDefinitionModelCollection.this[TopLevelTypeName name] {
+			get { return null; }
+		}
+		
+		ITypeDefinitionModel IReadOnlyList<ITypeDefinitionModel>.this[int index] {
+			get {
+				throw new ArgumentOutOfRangeException();
+			}
+		}
+		
+		int IReadOnlyCollection<ITypeDefinitionModel>.Count {
+			get { return 0; }
+		}
+		
+		IEnumerator<ITypeDefinitionModel> IEnumerable<ITypeDefinitionModel>.GetEnumerator()
+		{
+			return Enumerable.Empty<ITypeDefinitionModel>().GetEnumerator();
+		}
+		
+		IEnumerator IEnumerable.GetEnumerator()
+		{
+			return Enumerable.Empty<ITypeDefinitionModel>().GetEnumerator();
+		}
+	}
+}

src/Main/Base/Project/Dom/KeyedModelCollection.cs

@@ -0,0 +1,47 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using System.Collections.ObjectModel;
+using System.Collections.Specialized;
+
+namespace ICSharpCode.SharpDevelop.Dom
+{
+	/// <summary>
+	/// Observable KeyedCollection.
+	/// </summary>
+	public abstract class KeyedModelCollection<TKey, TItem> : KeyedCollection<TKey, TItem>, IModelCollection<TItem>
+	{
+		protected override void ClearItems()
+		{
+			base.ClearItems();
+			if (CollectionChanged != null)
+				CollectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
+		}
+		
+		protected override void InsertItem(int index, TItem item)
+		{
+			base.InsertItem(index, item);
+			if (CollectionChanged != null)
+				CollectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, item, index));
+		}
+		
+		protected override void RemoveItem(int index)
+		{
+			var oldItem = Items[index];
+			base.RemoveItem(index);
+			if (CollectionChanged != null)
+				CollectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, oldItem, index));
+		}
+		
+		protected override void SetItem(int index, TItem item)
+		{
+			var oldItem = Items[index];
+			base.SetItem(index, item);
+			if (CollectionChanged != null)
+				CollectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, oldItem, index));
+		}
+		
+		public event NotifyCollectionChangedEventHandler CollectionChanged;
+	}
+}

src/Main/Base/Project/ICSharpCode.SharpDevelop.csproj

@@ -95,6 +95,14 @@
     <Compile Include="..\..\ICSharpCode.SharpDevelop.BuildWorker\ExtendedBinaryReader.cs">
       <Link>Src\Project\MSBuildEngine\ExtendedBinaryReader.cs</Link>
     </Compile>
+    <Compile Include="Dom\ConcatModelCollection.cs" />
+    <Compile Include="Dom\IEntityModelContext.cs" />
+    <Compile Include="Dom\IMemberModel.cs" />
+    <Compile Include="Dom\IModelService.cs" />
+    <Compile Include="Dom\ITypeDefinitionModel.cs" />
+    <Compile Include="Dom\ITypeDefinitionModelCollection.cs" />
+    <Compile Include="Dom\KeyedModelCollection.cs" />
+    <Compile Include="Dom\IEntityModel.cs" />
     <Compile Include="Dom\IModelCollection.cs" />
     <Compile Include="Dom\ITreeNodeFactory.cs" />
     <Compile Include="Editor\DocumentServiceAttribute.cs" />

src/Main/Base/Project/Src/Project/AbstractProject.cs

@@ -11,10 +11,10 @@ using System.Linq;
 using System.Text;
 using System.Threading;
 using System.Xml.Linq;
-
 using ICSharpCode.Core;
 using ICSharpCode.NRefactory.TypeSystem;
 using ICSharpCode.SharpDevelop.Debugging;
+using ICSharpCode.SharpDevelop.Dom;
 using ICSharpCode.SharpDevelop.Gui;
 using ICSharpCode.SharpDevelop.Gui.OptionPanels;
 using ICSharpCode.SharpDevelop.Parser;
@@ -671,5 +671,11 @@ namespace ICSharpCode.SharpDevelop.Project
 				return false;
 			}
 		}
+		
+		public virtual ICSharpCode.SharpDevelop.Dom.ITypeDefinitionModelCollection TypeDefinitionModels {
+			get {
+				return EmptyTypeDefinitionModelCollection.Instance;
+			}
+		}
 	}
 }

src/Main/Base/Project/Src/Project/IProject.cs

@@ -9,8 +9,10 @@ using System.ComponentModel;
 using System.IO;
 using System.Xml;
 using System.Xml.Linq;
+
 using ICSharpCode.Core;
 using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.SharpDevelop.Dom;
 using ICSharpCode.SharpDevelop.Gui;
 using ICSharpCode.SharpDevelop.Parser;
 
@@ -319,6 +321,12 @@ namespace ICSharpCode.SharpDevelop.Project
 		/// This method is called by the parser service <b>within a per-file lock</b>.
 		/// </summary>
 		void OnParseInformationUpdated(ParseInformationEventArgs args);
+		
+		/// <summary>
+		/// Gets the models for the top-level type definitions in this project.
+		/// Never returns null, but may return a permanently empty collection if this project does not support such models.
+		/// </summary>
+		ITypeDefinitionModelCollection TypeDefinitionModels { get; }
 	}
 	
 	/// <summary>

src/Main/Base/Test/Dom/CSharpModelTests.cs

@@ -0,0 +1,82 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using ICSharpCode.NRefactory.CSharp;
+using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.SharpDevelop.Parser;
+using ICSharpCode.SharpDevelop.Project;
+using NUnit.Framework;
+using Rhino.Mocks;
+
+namespace ICSharpCode.SharpDevelop.Dom
+{
+	[TestFixture]
+	public class CSharpModelTests
+	{
+		IProject project;
+		IProjectContent projectContent;
+		IEntityModelContext context;
+		TopLevelTypeDefinitionModelCollection topLevelTypeModels;
+		
+		#region SetUp and other helper methods
+		[SetUp]
+		public virtual void SetUp()
+		{
+			SD.InitializeForUnitTests();
+			SD.Services.AddStrictMockService<IParserService>();
+			project = MockRepository.GenerateStrictMock<IProject>();
+			projectContent = new CSharpProjectContent().AddAssemblyReferences(AssemblyLoader.Corlib);
+			context = new ProjectEntityModelContext(project, ".cs");
+			topLevelTypeModels = new TopLevelTypeDefinitionModelCollection(context);
+			
+			SD.ParserService.Stub(p => p.GetCompilation(project)).WhenCalled(c => c.ReturnValue = projectContent.CreateCompilation());
+		}
+		
+		[TearDown]
+		public virtual void TearDown()
+		{
+			SD.TearDownForUnitTests();
+		}
+		
+		protected void AddCodeFile(string fileName, string code)
+		{
+			var oldFile = projectContent.GetFile(fileName);
+			Assert.IsNull(oldFile);
+			var newFile = Parse(fileName, code);
+			projectContent = projectContent.AddOrUpdateFiles(newFile);
+			topLevelTypeModels.NotifyParseInformationChanged(oldFile, newFile);
+		}
+		
+		IUnresolvedFile Parse(string fileName, string code)
+		{
+			var parser = new CSharpParser();
+			var syntaxTree = parser.Parse(code, fileName);
+			Assert.IsFalse(parser.HasErrors);
+			return syntaxTree.ToTypeSystem();
+		}
+		
+		protected void UpdateCodeFile(string fileName, string code)
+		{
+			var oldFile = projectContent.GetFile(fileName);
+			Assert.IsNotNull(oldFile);
+			var newFile = Parse(fileName, code);
+			projectContent = projectContent.AddOrUpdateFiles(newFile);
+			topLevelTypeModels.NotifyParseInformationChanged(oldFile, newFile);
+		}
+		
+		protected void RemoveCodeFile(string fileName)
+		{
+			var oldFile = projectContent.GetFile(fileName);
+			projectContent = projectContent.RemoveFiles(fileName);
+			topLevelTypeModels.NotifyParseInformationChanged(oldFile, null);
+		}
+		#endregion
+		
+		[Test]
+		public void EmptyProject()
+		{
+			Assert.AreEqual(0, topLevelTypeModels.Count);
+		}
+	}
+}

src/Main/Base/Test/Dom/ProjectEntityModelContextTests.cs

@@ -0,0 +1,42 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.SharpDevelop.Project;
+using NUnit.Framework;
+using Rhino.Mocks;
+
+namespace ICSharpCode.SharpDevelop.Dom
+{
+	[TestFixture]
+	public class ProjectEntityModelContextTests
+	{
+		IUnresolvedTypeDefinition CreateMockTypeDefinition(string fileName)
+		{
+			var typeDefinition = MockRepository.GenerateStrictMock<IUnresolvedTypeDefinition>();
+			var file = MockRepository.GenerateStrictMock<IUnresolvedFile>();
+			file.Stub(f => f.FileName).Return(fileName);
+			typeDefinition.Stub(td => td.UnresolvedFile).Return(file);
+			return typeDefinition;
+		}
+		
+		[Test]
+		public void XamlCodeBehindIsBetterThanXaml()
+		{
+			var context = new ProjectEntityModelContext(MockRepository.GenerateStrictMock<IProject>(), ".cs");
+			Assert.IsTrue(context.IsBetterPart(CreateMockTypeDefinition("Window.xaml.cs"), CreateMockTypeDefinition("Window.xaml")));
+			Assert.IsTrue(context.IsBetterPart(CreateMockTypeDefinition("Window.cs"), CreateMockTypeDefinition("Window.xaml")));
+			Assert.IsFalse(context.IsBetterPart(CreateMockTypeDefinition("Window.xaml"), CreateMockTypeDefinition("Window.xaml.cs")));
+			Assert.IsFalse(context.IsBetterPart(CreateMockTypeDefinition("Window.xaml"), CreateMockTypeDefinition("Window.cs")));
+		}
+		
+		[Test]
+		public void MainPartIsBetterThanDesigner()
+		{
+			var context = new ProjectEntityModelContext(MockRepository.GenerateStrictMock<IProject>(), ".cs");
+			Assert.IsTrue(context.IsBetterPart(CreateMockTypeDefinition("Form.cs"), CreateMockTypeDefinition("Form.Designer.cs")));
+			Assert.IsFalse(context.IsBetterPart(CreateMockTypeDefinition("Form.Designer.cs"), CreateMockTypeDefinition("Form.cs")));
+		}
+	}
+}

src/Main/Base/Test/ICSharpCode.SharpDevelop.Tests.csproj

@@ -78,6 +78,8 @@
     <Compile Include="AssemblyInfo.cs" />
     <Compile Include="CheckAssemblyFlags.cs" />
     <Compile Include="CodeConverterTests.cs" />
+    <Compile Include="Dom\CSharpModelTests.cs" />
+    <Compile Include="Dom\ProjectEntityModelContextTests.cs" />
     <Compile Include="Dom\TreeNodeFactoryServiceTests.cs" />
     <Compile Include="ExceptionClassOverridesTestFixture.cs" />
     <Compile Include="GenerateOverrideMethodTests.cs" />
@@ -114,6 +116,7 @@
     <Compile Include="StringTagProvider\MockProjectForTagProvider.cs" />
     <Compile Include="StringTagProvider\NullProjectStringTagProviderTestFixture.cs" />
     <Compile Include="StringTagProvider\ProjectTagsTestFixture.cs" />
+    <Compile Include="Utils\AssemblyLoader.cs" />
     <Compile Include="Utils\FakeMessageLoop.cs" />
     <Compile Include="Utils\MockAssembly.cs" />
     <Compile Include="Utils\MockComponent.cs" />
@@ -160,6 +163,10 @@
       <Project>{6C55B776-26D4-4DB3-A6AB-87E783B2F3D1}</Project>
       <Name>ICSharpCode.AvalonEdit</Name>
     </ProjectReference>
+    <ProjectReference Include="..\..\..\Libraries\NRefactory\ICSharpCode.NRefactory.CSharp\ICSharpCode.NRefactory.CSharp.csproj">
+      <Project>{53DCA265-3C3C-42F9-B647-F72BA678122B}</Project>
+      <Name>ICSharpCode.NRefactory.CSharp</Name>
+    </ProjectReference>
     <ProjectReference Include="..\..\..\Libraries\NRefactory\ICSharpCode.NRefactory\ICSharpCode.NRefactory.csproj">
       <Project>{3B2A5653-EC97-4001-BB9B-D90F1AF2C371}</Project>
       <Name>ICSharpCode.NRefactory</Name>

src/Main/Base/Test/Utils/AssemblyLoader.cs

@@ -0,0 +1,13 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using ICSharpCode.NRefactory.TypeSystem;
+
+namespace ICSharpCode.SharpDevelop
+{
+	public static class AssemblyLoader
+	{
+		public static readonly IUnresolvedAssembly Corlib = new CecilLoader { LazyLoad = true }.LoadAssemblyFile(typeof(object).Assembly.Location);
+	}
+}

src/Main/ICSharpCode.SharpDevelop.Widgets/Project/MyersDiff/MyersDiffAlgorithm.cs

@@ -59,11 +59,11 @@ namespace ICSharpCode.SharpDevelop.Widgets.MyersDiff
 	///
 	/// Example:
 	///
-	/// H E L L O W O R L D
-	/// ____
-	/// L \___
-	/// O \___
-	/// W \________
+    /// H E L L O W O R L D
+    ///   ____
+    /// L     \___
+    /// O         \___
+    /// W             \________
 	///
 	/// Since every D-path has exactly D horizontal or vertical elements, it can
 	/// only end on the diagonals -D, -D+2, ..., D-2, D.

src/Main/SharpDevelop/Dom/MemberModel.cs

@@ -0,0 +1,105 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using System.ComponentModel;
+using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.SharpDevelop.Parser;
+using ICSharpCode.SharpDevelop.Project;
+
+namespace ICSharpCode.SharpDevelop.Dom
+{
+	/// <summary>
+	/// A mutable class that can track a member as the solution is being changed.
+	/// </summary>
+	sealed class MemberModel : IMemberModel
+	{
+		/// <summary>
+		/// A strong reference to the parent TypeDefinitionModel.Members collection.
+		/// This is necessary to prevent the garbage collector from
+		/// freeing the weak reference to the collection while one of the member models
+		/// is still in use.
+		/// If we don't prevent this, the type definition model might create multiple
+		/// MemberModels for the same member.
+		/// </summary>
+		internal IModelCollection<MemberModel> strongParentCollectionReference;
+		
+		readonly IEntityModelContext context;
+		IUnresolvedMember member;
+		
+		public MemberModel(IEntityModelContext context, IUnresolvedMember member)
+		{
+			if (context == null)
+				throw new ArgumentNullException("context");
+			if (member == null)
+				throw new ArgumentNullException("member");
+			this.context = context;
+			this.member = member;
+		}
+		
+		public event PropertyChangedEventHandler PropertyChanged { add {} remove {} }
+		
+		public void Update(IUnresolvedMember newMember)
+		{
+			if (newMember == null)
+				throw new ArgumentNullException("newMember");
+			this.member = newMember;
+		}
+		
+		public IProject ParentProject {
+			get { return context.Project; }
+		}
+		
+		public IUnresolvedMember UnresolvedMember {
+			get { return member; }
+		}
+		
+		public EntityType EntityType {
+			get { return member.EntityType; }
+		}
+		
+		public DomRegion Region {
+			get { return member.Region; }
+		}
+		
+		public string Name {
+			get { return member.Name; }
+		}
+		
+		/// <summary>
+		/// Gets the full type name of the type that declares this member.
+		/// </summary>
+		public FullTypeName DeclaringTypeName {
+			get {
+				if (member.DeclaringTypeDefinition != null)
+					return member.DeclaringTypeDefinition.FullTypeName;
+				else
+					return new TopLevelTypeName(string.Empty, string.Empty);
+			}
+		}
+		
+		#region Resolve
+		public IMember Resolve()
+		{
+			var compilation = context.GetCompilation(null);
+			return member.Resolve(new SimpleTypeResolveContext(compilation.MainAssembly));
+		}
+		
+		public IMember Resolve(ISolutionSnapshotWithProjectMapping solutionSnapshot)
+		{
+			var compilation = context.GetCompilation(solutionSnapshot);
+			return member.Resolve(new SimpleTypeResolveContext(compilation.MainAssembly));
+		}
+		
+		IEntity IEntityModel.Resolve()
+		{
+			return Resolve();
+		}
+		
+		IEntity IEntityModel.Resolve(ISolutionSnapshotWithProjectMapping solutionSnapshot)
+		{
+			return Resolve(solutionSnapshot);
+		}
+		#endregion
+	}
+}

src/Main/SharpDevelop/Dom/TopLevelTypeDefinitionModelCollection.cs

@@ -0,0 +1,52 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using System.Collections;
+using System.Collections.ObjectModel;
+using System.Collections.Generic;
+using System.Collections.Specialized;
+using ICSharpCode.NRefactory.TypeSystem;
+
+namespace ICSharpCode.SharpDevelop.Dom
+{
+	/// <summary>
+	/// A TypeDefinitionModel-collection that holds models for all top-level types in a project content.
+	/// </summary>
+	sealed class TopLevelTypeDefinitionModelCollection : KeyedModelCollection<TopLevelTypeName, TypeDefinitionModel>
+	{
+		readonly IEntityModelContext context;
+		
+		public TopLevelTypeDefinitionModelCollection(IEntityModelContext context)
+		{
+			if (context == null)
+				throw new ArgumentNullException("context");
+			this.context = context;
+		}
+		
+		public TypeDefinitionModel this[FullTypeName fullTypeName] {
+			get {
+				TypeDefinitionModel model = base[fullTypeName.TopLevelTypeName];
+				for (int i = 0; i < fullTypeName.NestingLevel; i++) {
+					throw new NotImplementedException();
+				}
+				return model;
+			}
+		}
+		
+		/// <summary>
+		/// Updates the parse information.
+		/// </summary>
+		public void NotifyParseInformationChanged(IUnresolvedFile oldFile, IUnresolvedFile newFile)
+		{
+			if (oldFile != null) {
+				
+			}
+		}
+		
+		protected override TopLevelTypeName GetKeyForItem(TypeDefinitionModel item)
+		{
+			return item.FullTypeName.TopLevelTypeName;
+		}
+	}
+}

src/Main/SharpDevelop/Dom/TypeDefinitionModel.cs

@@ -0,0 +1,264 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Collections.Specialized;
+using System.ComponentModel;
+using System.Linq;
+
+using ICSharpCode.NRefactory.TypeSystem;
+using ICSharpCode.SharpDevelop.Parser;
+using ICSharpCode.SharpDevelop.Project;
+
+namespace ICSharpCode.SharpDevelop.Dom
+{
+	/// <summary>
+	/// A mutable class that can track a type definition as the solution is being changed.
+	/// </summary>
+	sealed class TypeDefinitionModel : ITypeDefinitionModel
+	{
+		readonly IEntityModelContext context;
+		readonly FullTypeName fullTypeName;
+		List<IUnresolvedTypeDefinition> parts;
+		
+		public TypeDefinitionModel(IEntityModelContext context, params IUnresolvedTypeDefinition[] parts)
+		{
+			if (context == null)
+				throw new ArgumentNullException("context");
+			if (parts.Length == 0)
+				throw new ArgumentException("Number of parts must not be zero");
+			this.context = context;
+			this.parts = new List<IUnresolvedTypeDefinition>(parts);
+			MovePrimaryPartToFront();
+			this.fullTypeName = parts[0].FullTypeName;
+		}
+		
+		void MovePrimaryPartToFront()
+		{
+			int bestPartIndex = 0;
+			for (int i = 1; i < parts.Count; i++) {
+				if (context.IsBetterPart(parts[i], parts[bestPartIndex]))
+					bestPartIndex = i;
+			}
+			IUnresolvedTypeDefinition primaryPart = parts[bestPartIndex];
+			for (int i = bestPartIndex; i > 0; i--) {
+				parts[i] = parts[i - 1];
+			}
+			parts[0] = primaryPart;
+		}
+		
+		/*
+		/// <summary>
+		/// Updates the type definition model by removing the old parts and adding the new ones.
+		/// </summary>
+		public void Update(IReadOnlyList<IUnresolvedTypeDefinition> removedParts, IReadOnlyList<IUnresolvedTypeDefinition> newParts)
+		{
+			SD.MainThread.VerifyAccess();
+			if (removedParts != null)
+				foreach (var p in removedParts)
+					parts.Remove(p);
+			if (newParts != null)
+				parts.AddRange(newParts);
+			
+			MemberModelCollection members;
+			if (membersWeakReference.TryGetTarget(out members)) {
+				members.Update(parts);
+			}
+		}*/
+		
+		public IProject ParentProject {
+			get { return context.Project; }
+		}
+		
+		public FullTypeName FullTypeName {
+			get { return fullTypeName; }
+		}
+		
+		public DomRegion Region {
+			get { return parts[0].Region; }
+		}
+		
+		public string Name {
+			get { return fullTypeName.Name; }
+		}
+		
+		#region Resolve
+		public ITypeDefinition Resolve()
+		{
+			var compilation = context.GetCompilation(null);
+			return compilation.MainAssembly.GetTypeDefinition(fullTypeName);
+		}
+		
+		public ITypeDefinition Resolve(ISolutionSnapshotWithProjectMapping solutionSnapshot)
+		{
+			var compilation = context.GetCompilation(solutionSnapshot);
+			return compilation.MainAssembly.GetTypeDefinition(fullTypeName);
+		}
+		
+		IEntity IEntityModel.Resolve()
+		{
+			return Resolve();
+		}
+		
+		IEntity IEntityModel.Resolve(ISolutionSnapshotWithProjectMapping solutionSnapshot)
+		{
+			return Resolve(solutionSnapshot);
+		}
+		#endregion
+		
+		public event PropertyChangedEventHandler PropertyChanged { add {} remove {} }
+		
+		#region Members collection
+		sealed class MemberCollection : IModelCollection<MemberModel>
+		{
+			readonly TypeDefinitionModel parent;
+			List<List<MemberModel>> lists = new List<List<MemberModel>>();
+			
+			public MemberCollection(TypeDefinitionModel parent)
+			{
+				this.parent = parent;
+			}
+			
+			public void Insert(int partIndex, IUnresolvedTypeDefinition newPart)
+			{
+				List<MemberModel> newItems = new List<MemberModel>(newPart.Members.Count);
+				foreach (var newMember in newPart.Members) {
+					newItems.Add(new MemberModel(parent.context, newMember) { strongParentCollectionReference = this });
+				}
+				lists.Insert(partIndex, newItems);
+				if (collectionChanged != null)
+					collectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, newItems, GetCount(partIndex)));
+			}
+			
+			public void Remove(int partIndex)
+			{
+				var oldItems = lists[partIndex];
+				lists.RemoveAt(partIndex);
+				if (collectionChanged != null)
+					collectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, oldItems, GetCount(partIndex)));
+			}
+			
+			public void Update(int partIndex, IUnresolvedTypeDefinition newPart)
+			{
+				List<MemberModel> list = lists[partIndex];
+				var newMembers = newPart.Members;
+				int startPos = 0;
+				// Look at the initial members and update them if they're matching
+				while (startPos < list.Count && startPos < newMembers.Count && IsMatch(list[startPos], newMembers[startPos])) {
+					list[startPos].Update(newMembers[startPos]);
+					startPos++;
+				}
+				// Look at the final members
+				int endPosOld = list.Count - 1;
+				int endPosNew = newMembers.Count - 1;
+				while (endPosOld >= startPos && endPosNew >= startPos && IsMatch(list[endPosOld], newMembers[endPosNew])) {
+					list[endPosOld--].Update(newMembers[endPosNew--]);
+				}
+				// [startPos, endPos] is the middle portion that contains all the changes
+				// Add one to endPos so that it's the exclusive end of the middle portion:
+				endPosOld++;
+				endPosNew++;
+				// [startPos, endPos)
+				
+				// Now we still need to update the members in between.
+				// We might try to be clever here and find a LCS so that we only update the members that were actually changed,
+				// or we might consider moving members around (INotifyCollectionChanged supports moves)
+				// However, the easiest solution by far is to just remove + readd the whole middle portion.
+				var oldItems = collectionChanged != null ? list.GetRange(startPos, endPosOld - startPos) : null;
+				list.RemoveRange(startPos, endPosOld - startPos);
+				var newItems = new MemberModel[endPosNew - startPos];
+				for (int i = 0; i < newItems.Length; i++) {
+					newItems[i] = new MemberModel(parent.context, newMembers[startPos + i]);
+					newItems[i].strongParentCollectionReference = this;
+				}
+				list.InsertRange(startPos, newItems);
+				if (collectionChanged != null)
+					collectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Replace, newItems, oldItems, GetCount(partIndex) + startPos));
+			}
+			
+			static bool IsMatch(MemberModel memberModel, IUnresolvedMember newMember)
+			{
+				return memberModel.EntityType == newMember.EntityType && memberModel.Name == newMember.Name;
+			}
+			
+			NotifyCollectionChangedEventHandler collectionChanged;
+			
+			public event NotifyCollectionChangedEventHandler CollectionChanged {
+				add {
+					collectionChanged += value;
+					// Set strong reference to collection while there are event listeners
+					if (collectionChanged != null)
+						parent.membersStrongReference = this;
+				}
+				remove {
+					collectionChanged -= value;
+					if (collectionChanged == null)
+						parent.membersStrongReference = null;
+				}
+			}
+			
+			int GetCount(int partIndex)
+			{
+				int count = 0;
+				for (int i = 0; i < partIndex; i++) {
+					count += lists[i].Count;
+				}
+				return count;
+			}
+			
+			public int Count {
+				get { return GetCount(lists.Count); }
+			}
+			
+			public IEnumerator<MemberModel> GetEnumerator()
+			{
+				return lists.SelectMany(i => i).GetEnumerator();
+			}
+			
+			IEnumerator IEnumerable.GetEnumerator()
+			{
+				return GetEnumerator();
+			}
+			
+			public MemberModel this[int index] {
+				get {
+					int inputIndex = 0;
+					while (index >= lists[inputIndex].Count) {
+						index -= lists[inputIndex].Count;
+						inputIndex++;
+					}
+					return lists[inputIndex][index];
+				}
+			}
+		}
+		
+		WeakReference<MemberCollection> membersWeakReference = new WeakReference<MemberCollection>(null);
+		
+		/// <summary>
+		/// Used to keep the member model collection alive while there are event listeners.
+		/// This is necessary to prevent us from creating multiple member models for the same member.
+		/// </summary>
+		MemberCollection membersStrongReference;
+		
+		public IModelCollection<IMemberModel> Members {
+			get {
+				SD.MainThread.VerifyAccess();
+				MemberCollection members;
+				if (!membersWeakReference.TryGetTarget(out members)) {
+					members = new MemberCollection(this);
+					membersWeakReference.SetTarget(members);
+				}
+				return members;
+			}
+		}
+		#endregion
+		
+		public IModelCollection<ITypeDefinitionModel> NestedTypes {
+			get {
+				throw new NotImplementedException();
+			}
+		}
+	}
+}

src/Main/SharpDevelop/SharpDevelop.csproj

@@ -81,7 +81,10 @@
     </Reference>
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Dom\MemberModel.cs" />
+    <Compile Include="Dom\TopLevelTypeDefinitionModelCollection.cs" />
     <Compile Include="Dom\TreeNodeFactoryService.cs" />
+    <Compile Include="Dom\TypeDefinitionModel.cs" />
     <Compile Include="OptionPanels\LoadSaveOptions.xaml.cs">
       <DependentUpon>LoadSaveOptions.xaml</DependentUpon>
       <SubType>Code</SubType>