Add support for custom data serialization in solutions

16 files changed, 940 insertions, 292 deletions

diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/ClassDataType.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/ClassDataType.cs
index 719e316efe..c1d0954759 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/ClassDataType.cs
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/ClassDataType.cs
@@ -313,15 +313,25 @@ namespace MonoDevelop.Core.Serialization
 			foreach (ItemProperty prop in Properties) {
 				if (prop.ReadOnly || !prop.CanSerialize (serCtx, obj))
 					continue;
+				
+				DataCollection col = itemCol;
+
 				object val = prop.GetValue (obj);
-				if (val == null)
-					continue;
-				if (!serCtx.IsDefaultValueSerializationForced (prop) && val.Equals (prop.DefaultValue))
+				if (val == null) {
+					if (serCtx.IncludeDeletedValues) {
+						if (prop.IsNested)
+							col = GetNestedCollection (col, prop.NameList, 0, true);
+						col.Add (new DataDeletedNode (prop.SingleName));
+					}
 					continue;
+				}
 				
-				DataCollection col = itemCol;
+				var isDefault = val.Equals (prop.DefaultValue);
+				if (isDefault && !serCtx.IsDefaultValueSerializationForced (prop))
+					continue;
+
 				if (prop.IsNested)
-					col = GetNestedCollection (col, prop.NameList, 0);
+					col = GetNestedCollection (col, prop.NameList, 0, isDefault);
 				
 				if (prop.ExpandedCollection) {
 					ICollectionHandler handler = prop.ExpandedCollectionHandler;
@@ -336,8 +346,12 @@ namespace MonoDevelop.Core.Serialization
 				}
 				else {
 					DataNode data = prop.Serialize (serCtx, obj, val);
-					if (data == null)
+					if (data == null) {
+						if (serCtx.IncludeDeletedValues)
+							col.Add (new DataDeletedNode (prop.SingleName));
 						continue;
+					}
+					data.IsDefaultValue = isDefault;
 					col.Add (data);
 				}
 			}
@@ -352,7 +366,7 @@ namespace MonoDevelop.Core.Serialization
 			return itemCol;
 		}
 		
-		DataCollection GetNestedCollection (DataCollection col, string[] nameList, int pos)
+		DataCollection GetNestedCollection (DataCollection col, string[] nameList, int pos, bool isDefault)
 		{
 			if (pos == nameList.Length - 1) return col;
 
@@ -361,8 +375,11 @@ namespace MonoDevelop.Core.Serialization
 				item = new DataItem ();
 				item.Name = nameList[pos];
 				col.Add (item);
+				item.IsDefaultValue = isDefault;
 			}
-			return GetNestedCollection (item.ItemData, nameList, pos + 1);
+			if (item.IsDefaultValue && !isDefault)
+				item.IsDefaultValue = false;
+			return GetNestedCollection (item.ItemData, nameList, pos + 1, isDefault);
 		}
 		
 		internal protected override object OnDeserialize (SerializationContext serCtx, object mapData, DataNode data)
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/DataCollection.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/DataCollection.cs
index f1b2f12b5d..970427f092 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/DataCollection.cs
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/DataCollection.cs
@@ -29,57 +29,28 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 
 namespace MonoDevelop.Core.Serialization
 {
 	[Serializable]
-	public class DataCollection: IEnumerable
+	public sealed class DataCollection: Collection<DataNode>
 	{
-		List<DataNode> list = new List<DataNode> ();
-		
-		public DataCollection ()
-		{
-		}
-		
-		protected List<DataNode> List {
-			get {
-				if (list == null)
-					list = new List<DataNode> ();
-				return list;
-			}
-		}
-		
-		public int Count
-		{
-			get { return list == null ? 0 : list.Count; }
-		}
-		
-		public virtual DataNode this [int n]
-		{
-			get { return List[n]; }
-			set { List[n] = value; }
-		}
-		
-		public virtual DataNode this [string name]
+		public DataNode this [string name]
 		{
 			get {
 				DataCollection col;
 				int i = FindData (name, out col, false);
-				if (i != -1) return col.List [i];
+				if (i != -1) return col [i];
 				else return null;
 			}
 		}
 		
 		int FindData (string name, out DataCollection colec, bool buildTree)
 		{
-			if (list == null) {
-				colec = null;
-				return -1;
-			}
-			
 			if (name.IndexOf ('/') == -1) {
-				for (int n=0; n<list.Count; n++) {
-					DataNode data = list [n];
+				for (int n=0; n<Items.Count; n++) {
+					DataNode data = Items [n];
 					if (data.Name == name) {
 						colec = this;
 						return n;
@@ -111,8 +82,8 @@ namespace MonoDevelop.Core.Serialization
 					}
 					
 					pos = -1;
-					for (int n=0; n<colec.List.Count; n++) {
-						data = colec.List [n];
+					for (int n=0; n<colec.Count; n++) {
+						data = colec [n];
 						if (data.Name == names [p]) {
 							pos = n; break;
 						}
@@ -122,47 +93,14 @@ namespace MonoDevelop.Core.Serialization
 			}
 		}
 		
-		public virtual IEnumerator GetEnumerator ()
-		{
-			return list == null ? Type.EmptyTypes.GetEnumerator() : list.GetEnumerator ();
-		}
-		
-		public void AddRange (DataCollection col)
-		{
-			foreach (DataNode node in col)
-				Add (node);
-		}
-		
-		public virtual void Add (DataNode entry)
-		{
-			if (entry == null)
-				throw new ArgumentNullException ("entry");
-				
-			List.Add (entry);
-		}
-		
-		public virtual void Insert (int index, DataNode entry)
-		{
-			if (entry == null)
-				throw new ArgumentNullException ("entry");
-
-			List.Insert (index, entry);
-		}
-		
-		public virtual void Add (DataNode entry, string itemPath)
+		public void Add (DataNode entry, string itemPath)
 		{
 			if (entry == null)
 				throw new ArgumentNullException ("entry");
 				
 			DataCollection col;
 			FindData (itemPath + "/", out col, true);
-			col.List.Add (entry);
-		}
-		
-		public virtual void Remove (DataNode entry)
-		{
-			if (list != null)
-				list.Remove (entry);
+			Add (entry);
 		}
 		
 		public DataNode Extract (string name)
@@ -170,25 +108,13 @@ namespace MonoDevelop.Core.Serialization
 			DataCollection col;
 			int i = FindData (name, out col, false);
 			if (i != -1) {
-				DataNode data = col.List [i];
-				col.list.RemoveAt (i);
+				DataNode data = col [i];
+				col.RemoveAt (i);
 				return data;
 			}
 			return null;
 		}
 		
-		public int IndexOf (DataNode entry)
-		{
-			if (list == null) return -1;
-			return list.IndexOf (entry);
-		}
-		
-		public virtual void Clear ()
-		{
-			if (list != null)
-				list.Clear ();
-		}
-		
 		public void Merge (DataCollection col)
 		{
 			ArrayList toAdd = new ArrayList ();
@@ -204,18 +130,5 @@ namespace MonoDevelop.Core.Serialization
 			foreach (DataNode node in toAdd)
 				Add (node);
 		}
-		
-		// Sorts the list using the specified key order
-		public void Sort (Dictionary<string,int> nameToPosition)
-		{
-			list.Sort (delegate (DataNode x, DataNode y) {
-				int p1, p2;
-				if (!nameToPosition.TryGetValue (x.Name, out p1))
-					p1 = int.MaxValue;
-				if (!nameToPosition.TryGetValue (y.Name, out p2))
-					p2 = int.MaxValue;
-				return p1.CompareTo (p2);
-			});
-		}
 	}
 }
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/DataDeletedValue.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/DataDeletedValue.cs
new file mode 100644
index 0000000000..55233bc925
--- /dev/null
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/DataDeletedValue.cs
@@ -0,0 +1,42 @@
+//
+// DataDeletedValue.cs
+//
+// Author:
+//       Lluis Sanchez Gual <lluis@xamarin.com>
+//
+// Copyright (c) 2015 Xamarin, Inc (http://www.xamarin.com)
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+
+namespace MonoDevelop.Core.Serialization
+{
+	/// <summary>
+	/// A data node that represents a value that has been deleted.
+	/// </summary>
+	[Serializable]
+	public class DataDeletedNode: DataNode
+	{
+		public DataDeletedNode (string name)
+		{
+			Name = name;
+		}
+	}
+}
+
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/DataItem.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/DataItem.cs
index 19bccb54aa..5fd5d9320d 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/DataItem.cs
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/DataItem.cs
@@ -27,6 +27,7 @@
 //
 
 using System;
+using System.Collections.Generic;
 
 namespace MonoDevelop.Core.Serialization
 {
@@ -65,6 +66,30 @@ namespace MonoDevelop.Core.Serialization
 			if (data == null) return null;
 			return data.Extract (name);
 		}
+
+		internal void UpdateFromItem (DataItem item, HashSet<DataItem> removedItems)
+		{
+			foreach (var d in item.ItemData) {
+				var current = ItemData[d.Name];
+				if (current != null) {
+					if (d.IsDefaultValue || d is DataDeletedNode) {
+						if (current is DataItem)
+							removedItems.Add ((DataItem)current);
+						ItemData.Remove (current);
+					}
+					else if (current.GetType () != d.GetType () || current is DataValue) {
+						var i = ItemData.IndexOf (current);
+						ItemData [i] = d;
+						if (current is DataItem)
+							removedItems.Add ((DataItem)current);
+					} else if (current is DataItem) {
+						((DataItem)current).UpdateFromItem ((DataItem)d, removedItems);
+					}
+				} else if (!d.IsDefaultValue && !(d is DataDeletedNode)) {
+					ItemData.Add (d);
+				}
+			}
+		}
 		
 		public override string ToString ()
 		{
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/DataNode.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/DataNode.cs
index 1f6a847719..98b1cd9b29 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/DataNode.cs
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/DataNode.cs
@@ -44,5 +44,11 @@ namespace MonoDevelop.Core.Serialization
 		{
 			return "";
 		}
+
+		/// <summary>
+		/// Gets or sets a value indicating whether this instance is default value.
+		/// </summary>
+		/// <remarks>This flag is set when an object is serialized using the IncludeDefaultValues or IncludeDeletedValues</remarks>
+		public bool IsDefaultValue { get; set; }
 	}
 }
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/SerializationContext.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/SerializationContext.cs
index d3179c26b8..ffa277d0d8 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/SerializationContext.cs
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Core.Serialization/SerializationContext.cs
@@ -81,9 +81,18 @@ namespace MonoDevelop.Core.Serialization
 				monitor = value;
 			}
 		}
-		
+
+		/// <summary>
+		/// When set to true, properties with default values are serialized
+		/// </summary>
 		public bool IncludeDefaultValues { get; set; }
 		
+		/// <summary>
+		/// When set to true, properties with default values are serialized, and properties that have
+		/// been removed are serialized as a DataDeletedValue.
+		/// </summary>
+		public bool IncludeDeletedValues { get; set; }
+
 		public void ResetDefaultValueSerialization ()
 		{
 			forcedSerializationProps = null;
@@ -98,7 +107,7 @@ namespace MonoDevelop.Core.Serialization
 		
 		public bool IsDefaultValueSerializationForced (ItemProperty prop)
 		{
-			if (IncludeDefaultValues)
+			if (IncludeDefaultValues || IncludeDeletedValues)
 				return true;
 			else if (forcedSerializationProps != null)
 				return forcedSerializationProps.Contains (prop);
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Core.csproj b/main/src/core/MonoDevelop.Core/MonoDevelop.Core.csproj
index c30bf344ae..d980d4c1ce 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Core.csproj
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Core.csproj
@@ -505,6 +505,8 @@
     <Compile Include="MonoDevelop.Projects.Extensions\ImportRedirectTypeNode.cs" />
     <Compile Include="MonoDevelop.Projects.Formats.MSBuild\FileUtil.cs" />
     <Compile Include="MonoDevelop.Projects.Formats.MSBuild\DefaultMSBuildEngine.cs" />
+    <Compile Include="MonoDevelop.Projects\SolutionDataSectionAttribute.cs" />
+    <Compile Include="MonoDevelop.Core.Serialization\DataDeletedValue.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="Makefile.am" />
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.Formats.MSBuild/IMSBuildPropertySet.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.Formats.MSBuild/IMSBuildPropertySet.cs
index c005edddbb..8bee78d40b 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.Formats.MSBuild/IMSBuildPropertySet.cs
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.Formats.MSBuild/IMSBuildPropertySet.cs
@@ -139,10 +139,10 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 					continue;
 				object readVal = null;
 				if (prop.ReturnType == typeof(FilePath)) {
-					FilePath def = prop.Attribute.DefaultValue != null ? (string)prop.Attribute.DefaultValue : (string)null;
+					FilePath def = (string)prop.Attribute.DefaultValue;
 					readVal = pset.GetPathValue (prop.Name, def);
 				} else if (prop.Attribute is ProjectPathItemProperty && prop.ReturnType == typeof(string)) {
-					FilePath def = prop.Attribute.DefaultValue != null ? (string)prop.Attribute.DefaultValue : (string)null;
+					FilePath def = (string)prop.Attribute.DefaultValue;
 					readVal = pset.GetPathValue (prop.Name, def);
 					readVal = readVal.ToString ();
 				} else if (prop.ReturnType == typeof(string)) {
@@ -154,6 +154,199 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			}
 		}
 
+		static DataContext solutionDataContext = new DataContext ();
+
+		public static void WriteObjectProperties (this SlnPropertySet pset, object ob)
+		{
+			DataSerializer ser = new DataSerializer (solutionDataContext);
+			ser.SerializationContext.BaseFile = pset.ParentFile.FileName;
+			ser.SerializationContext.IncludeDeletedValues = true;
+			var data = ser.Serialize (ob, ob.GetType()) as DataItem;
+			if (data != null)
+				WriteDataItem (pset, data);
+		}
+
+		public static void ReadObjectProperties (this SlnPropertySet pset, object ob)
+		{
+			DataSerializer ser = new DataSerializer (solutionDataContext);
+			ser.SerializationContext.BaseFile = pset.ParentFile.FileName;
+			var data = ReadDataItem (pset);	
+			ser.Deserialize (ob, data);
+		}
+
+		static void WriteDataItem (SlnPropertySet pset, DataItem item)
+		{
+			HashSet<DataItem> removedItems = new HashSet<DataItem> ();
+			Dictionary<DataNode,int> ids = new Dictionary<DataNode, int> ();
+
+			// First of all read the existing data item, since we want to keep data that has not been modified
+			// The ids collection is filled with a map of items and their ids
+			var currentItem = ReadDataItem (pset, ids);
+
+			// UpdateFromItem will add new data to the item, it will remove the data that has been removed, and
+			// will ignore unknown data that has not been set or removed
+			currentItem.UpdateFromItem (item, removedItems);
+
+			// List of IDs that are not used anymore and can be reused when writing the item
+			var unusedIds = new Queue<int> (removedItems.Select (it => ids[it]).OrderBy (i => i));
+
+			// Calculate the next free id, to be used when adding new items
+			var usedIds = ids.Where (p => !removedItems.Contains (p.Key)).Select (p => p.Value).ToArray ();
+			int nextId = usedIds.Length > 0 ? usedIds.Max () + 1 : 0;
+
+			// Clear all properties, since we are writing them again
+			pset.Clear ();
+
+			foreach (DataNode val in currentItem.ItemData)
+				WriteDataNode (pset, "", val, ids, unusedIds, ref nextId);
+		}
+
+		static void WriteDataNode (SlnPropertySet pset, string prefix, DataNode node, Dictionary<DataNode,int> ids, Queue<int> unusedIds, ref int id)
+		{
+			string name = node.Name;
+			string newPrefix = prefix.Length > 0 ? prefix + "." + name: name;
+
+			if (node is DataValue) {
+				DataValue val = (DataValue) node;
+				string value = EncodeString (val.Value);
+				pset.SetValue (newPrefix, value);
+			}
+			else {
+				DataItem it = (DataItem) node;
+				int newId;
+				if (!ids.TryGetValue (node, out newId))
+					newId = unusedIds.Count > 0 ? unusedIds.Dequeue () : (id++);
+				pset.SetValue (newPrefix, "$" + newId);
+				newPrefix = "$" + newId;
+				foreach (DataNode cn in it.ItemData)
+					WriteDataNode (pset, newPrefix, cn, ids, unusedIds, ref id);
+			}
+		}
+
+		static string EncodeString (string val)
+		{
+			if (val.Length == 0)
+				return val;
+
+			int i = val.IndexOfAny (new char[] {'\n','\r','\t'});
+			if (i != -1 || val [0] == '@') {
+				StringBuilder sb = new StringBuilder ();
+				if (i != -1) {
+					int fi = val.IndexOf ('\\');
+					if (fi != -1 && fi < i) i = fi;
+					sb.Append (val.Substring (0,i));
+				} else
+					i = 0;
+				for (int n = i; n < val.Length; n++) {
+					char c = val [n];
+					if (c == '\r')
+						sb.Append (@"\r");
+					else if (c == '\n')
+						sb.Append (@"\n");
+					else if (c == '\t')
+						sb.Append (@"\t");
+					else if (c == '\\')
+						sb.Append (@"\\");
+					else
+						sb.Append (c);
+				}
+				val = "@" + sb.ToString ();
+			}
+			char fc = val [0];
+			char lc = val [val.Length - 1];
+			if (fc == ' ' || fc == '"' || fc == '$' || lc == ' ')
+				val = "\"" + val + "\"";
+			return val;
+		}
+
+		static string DecodeString (string val)
+		{
+			val = val.Trim (' ', '\t');
+			if (val.Length == 0)
+				return val;
+			if (val [0] == '\"')
+				val = val.Substring (1, val.Length - 2);
+			if (val [0] == '@') {
+				StringBuilder sb = new StringBuilder (val.Length);
+				for (int n = 1; n < val.Length; n++) {
+					char c = val [n];
+					if (c == '\\') {
+						c = val [++n];
+						if (c == 'r') c = '\r';
+						else if (c == 'n') c = '\n';
+						else if (c == 't') c = '\t';
+					}
+					sb.Append (c);
+				}
+				return sb.ToString ();
+			}
+			else
+				return val;
+		}
+
+		static DataItem ReadDataItem (SlnPropertySet pset)
+		{
+			return ReadDataItem (pset, null);
+		}
+
+		static DataItem ReadDataItem (SlnPropertySet pset, Dictionary<DataNode,int> ids)
+		{
+			DataItem it = new DataItem ();
+
+			var lines = pset.ToArray ();
+
+			int lineNum = 0;
+			int lastLine = lines.Length - 1;
+			while (lineNum <= lastLine) {
+				if (!ReadDataNode (it, lines, lastLine, "", ids, ref lineNum))
+					lineNum++;
+			}
+			return it;
+		}
+
+		static bool ReadDataNode (DataItem item, KeyValuePair<string,string>[] lines, int lastLine, string prefix, Dictionary<DataNode,int> ids, ref int lineNum)
+		{
+			var s = lines [lineNum];
+
+			string name = s.Key;
+			if (name.Length == 0) {
+				lineNum++;
+				return true;
+			}
+
+			// Check if the line belongs to the current item
+			if (prefix.Length > 0) {
+				if (!s.Key.StartsWith (prefix + ".", StringComparison.Ordinal))
+					return false;
+				name = s.Key.Substring (prefix.Length + 1);
+			} else {
+				if (s.Key.StartsWith ("$", StringComparison.Ordinal))
+					return false;
+			}
+
+			string value = s.Value;
+			if (value.StartsWith ("$", StringComparison.Ordinal)) {
+				// New item
+				DataItem child = new DataItem ();
+				child.Name = name;
+				int id;
+				if (ids != null && int.TryParse (value.Substring (1), out id))
+					ids [child] = id;
+				lineNum++;
+				while (lineNum <= lastLine) {
+					if (!ReadDataNode (child, lines, lastLine, value, ids, ref lineNum))
+						break;
+				}
+				item.ItemData.Add (child);
+			} else {
+				value = DecodeString (value);
+				DataValue val = new DataValue (name, value);
+				item.ItemData.Add (val);
+				lineNum++;
+			}
+			return true;
+		}
+
 		internal static void WriteExternalProjectProperties (this MSBuildProject project, object ob, Type typeToScan, bool includeBaseMembers = false)
 		{
 			var props = GetMembers (typeToScan, includeBaseMembers);
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.Formats.MSBuild/SlnFile.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.Formats.MSBuild/SlnFile.cs
index f1af02ae84..a76cb4f75c 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.Formats.MSBuild/SlnFile.cs
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.Formats.MSBuild/SlnFile.cs
@@ -8,6 +8,7 @@ using System.Collections;
 using MonoDevelop.Core;
 using MonoDevelop.Projects.Text;
 using System.Text.RegularExpressions;
+using System.Globalization;
 
 namespace MonoDevelop.Projects.Formats.MSBuild
 {
@@ -34,6 +35,8 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 
 		public SlnFile ()
 		{
+			projects.ParentFile = this;
+			sections.ParentFile = this;
 		}
 
 		/// <summary>
@@ -43,7 +46,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 		/// <param name="file">File.</param>
 		public static string GetFileVersion (string file)
 		{
-			string strVersion = null;
+			string strVersion;
 			using (var reader = new StreamReader (file)) {
 				var strInput = reader.ReadLine();
 				if (strInput == null)
@@ -70,21 +73,32 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 		/// The directory to be used as base for converting absolute paths to relative
 		/// </summary>
 		public FilePath BaseDirectory {
-			get;
-			set;
+			get { return FileName.ParentDirectory; }
 		}
 
+		/// <summary>
+		/// Gets the solution configurations section.
+		/// </summary>
+		/// <value>The solution configurations section.</value>
 		public SlnPropertySet SolutionConfigurationsSection {
-			get { return sections.GetOrCreateSection ("SolutionConfigurationPlatforms", "preSolution").Properties; }
+			get { return sections.GetOrCreateSection ("SolutionConfigurationPlatforms", SlnSectionType.PreProcess).Properties; }
 		}
 
+		/// <summary>
+		/// Gets the project configurations section.
+		/// </summary>
+		/// <value>The project configurations section.</value>
 		public SlnPropertySetCollection ProjectConfigurationsSection {
-			get { return sections.GetOrCreateSection ("ProjectConfigurationPlatforms", "postSolution").NestedPropertySets; }
+			get { return sections.GetOrCreateSection ("ProjectConfigurationPlatforms", SlnSectionType.PostProcess).NestedPropertySets; }
 		}
 
+		/// <summary>
+		/// Gets the custom MonoDevelop properties section
+		/// </summary>
+		/// <value>The custom mono develop properties.</value>
 		public SlnPropertySet CustomMonoDevelopProperties {
 			get {
-				var s = sections.GetOrCreateSection ("MonoDevelopProperties", "preSolution"); 
+				var s = sections.GetOrCreateSection ("MonoDevelopProperties", SlnSectionType.PreProcess); 
 				s.SkipIfEmpty = true;
 				return s.Properties;
 			}
@@ -98,8 +112,11 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			get { return projects; }
 		}
 
+		public FilePath FileName { get; set; }
+
 		public void Read (string file)
 		{
+			FileName = file;
 			format = FileUtil.GetTextFormatInfo (file);
 
 			using (var sr = new StreamReader (file))
@@ -116,19 +133,19 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			while ((line = reader.ReadLine ()) != null) {
 				curLineNum++;
 				line = line.Trim ();
-				if (line.StartsWith ("Microsoft Visual Studio Solution File")) {
+				if (line.StartsWith ("Microsoft Visual Studio Solution File", StringComparison.Ordinal)) {
 					int i = line.LastIndexOf (' ');
 					if (i == -1)
 						throw new InvalidSolutionFormatException (curLineNum);
 					FormatVersion = line.Substring (i + 1);
 					prefixBlankLines = curLineNum - 1;
 				}
-				if (line.StartsWith ("# ")) {
+				if (line.StartsWith ("# ", StringComparison.Ordinal)) {
 					if (!productRead) {
 						productRead = true;
 						ProductDescription = line.Substring (2);
 					}
-				} else if (line.StartsWith ("Project")) {
+				} else if (line.StartsWith ("Project", StringComparison.Ordinal)) {
 					SlnProject p = new SlnProject ();
 					p.Read (reader, line, ref curLineNum);
 					projects.Add (p);
@@ -141,7 +158,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 						line = line.Trim ();
 						if (line == "EndGlobal") {
 							break;
-						} else if (line.StartsWith ("GlobalSection")) {
+						} else if (line.StartsWith ("GlobalSection", StringComparison.Ordinal)) {
 							var sec = new SlnSection ();
 							sec.Read (reader, line, ref curLineNum);
 							sections.Add (sec);
@@ -160,6 +177,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 
 		public void Write (string file)
 		{
+			FileName = file;
 			var sw = new StringWriter ();
 			Write (sw);
 			TextFile.WriteFile (file, sw.ToString(), format.ByteOrderMark, true);
@@ -189,6 +207,18 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 	{
 		SlnSectionCollection sections = new SlnSectionCollection ();
 
+		SlnFile parentFile;
+
+		public SlnFile ParentFile {
+			get {
+				return parentFile;
+			}
+			internal set {
+				parentFile = value;
+				sections.ParentFile = parentFile;
+			}
+		}
+
 		public string Id { get; set; }
 		public string TypeGuid { get; set; }
 		public string Name { get; set; }
@@ -241,7 +271,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 				if (line == "EndProject") {
 					return;
 				}
-				if (line.StartsWith ("ProjectSection")) {
+				if (line.StartsWith ("ProjectSection", StringComparison.Ordinal)) {
 					if (sections == null)
 						sections = new SlnSectionCollection ();
 					var sec = new SlnSection ();
@@ -288,8 +318,11 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 
 		public string Id { get; set; }
 		public int Line { get; private set; }
+
 		internal bool Processed { get; set; }
 
+		public SlnFile ParentFile { get; internal set; }
+
 		public bool IsEmpty {
 			get {
 				return (properties == null || properties.Count == 0) && (nestedPropertySets == null || nestedPropertySets.All (t => t.IsEmpty));
@@ -313,6 +346,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			get {
 				if (properties == null) {
 					properties = new SlnPropertySet ();
+					properties.ParentSection = this;
 					if (sectionLines != null) {
 						foreach (var line in sectionLines)
 							properties.ReadLine (line, Line);
@@ -326,7 +360,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 		public SlnPropertySetCollection NestedPropertySets {
 			get {
 				if (nestedPropertySets == null) {
-					nestedPropertySets = new SlnPropertySetCollection ();
+					nestedPropertySets = new SlnPropertySetCollection (this);
 					if (sectionLines != null)
 						LoadPropertySets ();
 				}
@@ -334,7 +368,24 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			}
 		}
 
-		public string SectionType { get; set; }
+		public SlnSectionType SectionType { get; set; }
+
+		SlnSectionType ToSectionType (int curLineNum, string s)
+		{
+			if (s == "preSolution" || s == "preProject")
+				return SlnSectionType.PreProcess;
+			if (s == "postSolution" || s == "postProject")
+				return SlnSectionType.PostProcess;
+			throw new InvalidSolutionFormatException (curLineNum, "Invalid section type: " + s);
+		}
+
+		string FromSectionType (bool isProjectSection, SlnSectionType type)
+		{
+			if (type == SlnSectionType.PreProcess)
+				return isProjectSection ? "preProject" : "preSolution";
+			else
+				return isProjectSection ? "postProject" : "postSolution";
+		}
 
 		internal void Read (TextReader reader, string line, ref int curLineNum)
 		{
@@ -349,7 +400,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			Id = line.Substring (k + 1, k2 - k - 1);
 
 			k = line.IndexOf ('=', k2);
-			SectionType = line.Substring (k + 1).Trim ();
+			SectionType = ToSectionType (curLineNum, line.Substring (k + 1).Trim ());
 
 			var endTag = "End" + tag;
 
@@ -396,7 +447,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			writer.Write ('(');
 			writer.Write (Id);
 			writer.Write (") = ");
-			writer.WriteLine (SectionType);
+			writer.WriteLine (FromSectionType (sectionTag == "ProjectSection", SectionType));
 			if (sectionLines != null) {
 				foreach (var l in sectionLines)
 					writer.WriteLine ("\t\t" + l);
@@ -410,18 +461,36 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 		}
 	}
 
+	/// <summary>
+	/// A collection of properties
+	/// </summary>
 	public class SlnPropertySet: IDictionary<string,string>
 	{
 		OrderedDictionary values = new OrderedDictionary ();
 		bool isMetadata;
 
 		internal bool Processed { get; set; }
+
+		public SlnFile ParentFile {
+			get { return ParentSection != null ? ParentSection.ParentFile : null; }
+		}
+
+		public SlnSection ParentSection { get; set; }
+
+		/// <summary>
+		/// Text file line of this section in the original file
+		/// </summary>
+		/// <value>The line.</value>
 		public int Line { get; private set; }
 
-		public SlnPropertySet ()
+		internal SlnPropertySet ()
 		{
 		}
 
+		/// <summary>
+		/// Creates a new property set with the specified ID
+		/// </summary>
+		/// <param name="id">Identifier.</param>
 		public SlnPropertySet (string id)
 		{
 			Id = id;
@@ -432,6 +501,10 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			this.isMetadata = isMetadata;
 		}
 
+		/// <summary>
+		/// Gets a value indicating whether this property set is empty.
+		/// </summary>
+		/// <value><c>true</c> if this instance is empty; otherwise, <c>false</c>.</value>
 		public bool IsEmpty {
 			get {
 				return values.Count == 0;
@@ -464,28 +537,163 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			}
 		}
 
+		/// <summary>
+		/// Gets the identifier of the property set
+		/// </summary>
+		/// <value>The identifier.</value>
 		public string Id { get; private set; }
 
-		public string GetValue (string key)
+		public string GetValue (string name, string defaultValue = null)
 		{
-			return (string) values [key];
+			string res;
+			if (TryGetValue (name, out res))
+				return res;
+			else
+				return defaultValue;
 		}
 
-		public void SetValue (string key, string value)
+		public FilePath GetPathValue (string name, FilePath defaultValue = default(FilePath), bool relativeToSolution = true, FilePath relativeToPath = default(FilePath))
 		{
-			values [key] = value;
+			string val;
+			if (TryGetValue (name, out val)) {
+				string baseDir = null;
+				if (relativeToPath != null) {
+					baseDir = relativeToPath;
+				} else if (relativeToSolution && ParentFile != null && ParentFile.FileName != null) {
+					baseDir = ParentFile.FileName.ParentDirectory;
+				}
+				return MSBuildProjectService.FromMSBuildPath (baseDir, val);
+			}
+			else
+				return defaultValue;
+		}
+
+		public bool TryGetPathValue (string name, out FilePath value, FilePath defaultValue = default(FilePath), bool relativeToSolution = true, FilePath relativeToPath = default(FilePath))
+		{
+			string val;
+			if (TryGetValue (name, out val)) {
+				string baseDir = null;
+
+				if (relativeToPath != null) {
+					baseDir = relativeToPath;
+				} else if (relativeToSolution && ParentFile != null && ParentFile.FileName != null) {
+					baseDir = ParentFile.FileName.ParentDirectory;
+				}
+				string path;
+				var res = MSBuildProjectService.FromMSBuildPath (baseDir, val, out path);
+				value = path;
+				return res;
+			}
+			else {
+				value = defaultValue;
+				return value != default(FilePath);
+			}
+		}
+
+		public T GetValue<T> (string name)
+		{
+			return (T) GetValue (name, typeof(T), default(T));
+		}
+
+		public T GetValue<T> (string name, T defaultValue)
+		{
+			return (T) GetValue (name, typeof(T), defaultValue);
+		}
+
+		public object GetValue (string name, Type t, object defaultValue)
+		{
+			string val;
+			if (TryGetValue (name, out val)) {
+				if (t == typeof(bool))
+					return (object) val.Equals ("true", StringComparison.InvariantCultureIgnoreCase);
+				if (t.IsEnum)
+					return Enum.Parse (t, val, true);
+				if (t.IsGenericType && t.GetGenericTypeDefinition () == typeof(Nullable<>)) {
+					var at = t.GetGenericArguments () [0];
+					if (string.IsNullOrEmpty (val))
+						return null;
+					return Convert.ChangeType (val, at, CultureInfo.InvariantCulture);
+
+				}
+				return Convert.ChangeType (val, t, CultureInfo.InvariantCulture);
+			}
+			else
+				return defaultValue;
+		}
+
+		public void SetValue (string name, string value, string defaultValue = null, bool preserveExistingCase = false)
+		{
+			if (value == null && defaultValue == "")
+				value = "";
+			if (value == defaultValue) {
+				// if the value is default, only remove the property if it was not already the default
+				// to avoid unnecessary project file churn
+				string res;
+				if (TryGetValue (name, out res) && !string.Equals (defaultValue ?? "", res, preserveExistingCase ? StringComparison.OrdinalIgnoreCase : StringComparison.Ordinal))
+					Remove (name);
+				return;
+			}
+			string currentValue;
+			if (preserveExistingCase && TryGetValue (name, out currentValue) && string.Equals (value, currentValue, StringComparison.OrdinalIgnoreCase))
+				return;
+			values [name] = value;
+		}
+
+		public void SetValue (string name, FilePath value, FilePath defaultValue = default(FilePath), bool relativeToSolution = true, FilePath relativeToPath = default(FilePath))
+		{
+			var isDefault = value.CanonicalPath == defaultValue.CanonicalPath;
+			if (isDefault) {
+				// if the value is default, only remove the property if it was not already the default
+				// to avoid unnecessary project file churn
+				if (ContainsKey (name) && (defaultValue == null || defaultValue != GetPathValue (name, relativeToSolution:relativeToSolution, relativeToPath:relativeToPath)))
+					Remove (name);
+				return;
+			}
+			string baseDir = null;
+			if (relativeToPath != null) {
+				baseDir = relativeToPath;
+			} else if (relativeToSolution && ParentFile != null && ParentFile.FileName != null) {
+				baseDir = ParentFile.FileName.ParentDirectory;
+			}
+			values [name] = MSBuildProjectService.ToMSBuildPath (baseDir, value, false);
+		}
+
+		public void SetValue (string name, object value, object defaultValue = null)
+		{
+			var isDefault = object.Equals (value, defaultValue);
+			if (isDefault) {
+				// if the value is default, only remove the property if it was not already the default
+				// to avoid unnecessary project file churn
+				if (ContainsKey (name) && (defaultValue == null || !object.Equals (defaultValue, GetValue (name, defaultValue.GetType (), null))))
+					Remove (name);
+				return;
+			}
+
+			if (value is bool)
+				values [name] = (bool)value ? "TRUE" : "FALSE";
+			else
+				values [name] = Convert.ToString (value, CultureInfo.InvariantCulture);
 		}
 
-		public void Add (string key, string value)
+		void IDictionary<string,string>.Add (string key, string value)
 		{
 			SetValue (key, value);
 		}
 
+		/// <summary>
+		/// Determines whether the current instance contains an entry with the specified key
+		/// </summary>
+		/// <returns><c>true</c>, if key was containsed, <c>false</c> otherwise.</returns>
+		/// <param name="key">Key.</param>
 		public bool ContainsKey (string key)
 		{
 			return values.Contains (key);
 		}
 
+		/// <summary>
+		/// Removes a property
+		/// </summary>
+		/// <param name="key">Property name</param>
 		public bool Remove (string key)
 		{
 			var wasThere = values.Contains (key);
@@ -493,12 +701,22 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			return wasThere;
 		}
 
+		/// <summary>
+		/// Tries to get the value of a property
+		/// </summary>
+		/// <returns><c>true</c>, if the property exists, <c>false</c> otherwise.</returns>
+		/// <param name="key">Property name</param>
+		/// <param name="value">Value.</param>
 		public bool TryGetValue (string key, out string value)
 		{
 			value = (string) values [key];
 			return value != null;
 		}
 
+		/// <summary>
+		/// Gets or sets the value of a property
+		/// </summary>
+		/// <param name="index">Index.</param>
 		public string this [string index] {
 			get {
 				return (string) values [index];
@@ -518,7 +736,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			get { return values.Keys.Cast<string> ().ToList (); }
 		}
 
-		public void Add (KeyValuePair<string, string> item)
+		void ICollection<KeyValuePair<string, string>>.Add (KeyValuePair<string, string> item)
 		{
 			SetValue (item.Key, item.Value);
 		}
@@ -534,7 +752,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 				values.Remove (k);
 		}
 
-		public bool Contains (KeyValuePair<string, string> item)
+		bool ICollection<KeyValuePair<string, string>>.Contains (KeyValuePair<string, string> item)
 		{
 			var val = GetValue (item.Key);
 			return val == item.Value;
@@ -546,9 +764,9 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 				array [arrayIndex++] = new KeyValuePair<string, string> ((string)de.Key, (string)de.Value);
 		}
 
-		public bool Remove (KeyValuePair<string, string> item)
+		bool ICollection<KeyValuePair<string, string>>.Remove (KeyValuePair<string, string> item)
 		{
-			if (Contains (item)) {
+			if (((ICollection<KeyValuePair<string, string>>)this).Contains (item)) {
 				Remove (item.Key);
 				return true;
 			} else
@@ -561,7 +779,14 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			}
 		}
 
-		public bool IsReadOnly {
+		internal void SetLines (IEnumerable<KeyValuePair<string,string>> lines)
+		{
+			values.Clear ();
+			foreach (var line in lines)
+				values [line.Key] = line.Value;
+		}
+
+		bool ICollection<KeyValuePair<string, string>>.IsReadOnly {
 			get {
 				return false;
 			}
@@ -582,6 +807,19 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 
 	public class SlnProjectCollection: Collection<SlnProject>
 	{
+		SlnFile parentFile;
+
+		internal SlnFile ParentFile {
+			get {
+				return parentFile;
+			}
+			set {
+				parentFile = value;
+				foreach (var it in this)
+					it.ParentFile = parentFile;
+			}
+		}
+
 		public SlnProject GetProject (string id)
 		{
 			return this.FirstOrDefault (s => s.Id == id);
@@ -596,16 +834,60 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			}
 			return p;
 		}
+
+		protected override void InsertItem (int index, SlnProject item)
+		{
+			base.InsertItem (index, item);
+			item.ParentFile = ParentFile;
+		}
+
+		protected override void SetItem (int index, SlnProject item)
+		{
+			base.SetItem (index, item);
+			item.ParentFile = ParentFile;
+		}
+
+		protected override void RemoveItem (int index)
+		{
+			var it = this [index];
+			it.ParentFile = null;
+			base.RemoveItem (index);
+		}
+
+		protected override void ClearItems ()
+		{
+			foreach (var it in this)
+				it.ParentFile = null;
+			base.ClearItems ();
+		}
 	}
 
 	public class SlnSectionCollection: Collection<SlnSection>
 	{
+		SlnFile parentFile;
+
+		internal SlnFile ParentFile {
+			get {
+				return parentFile;
+			}
+			set {
+				parentFile = value;
+				foreach (var it in this)
+					it.ParentFile = parentFile;
+			}
+		}
+
 		public SlnSection GetSection (string id)
 		{
 			return this.FirstOrDefault (s => s.Id == id);
 		}
 
-		public SlnSection GetOrCreateSection (string id, string sectionType)
+		public SlnSection GetSection (string id, SlnSectionType sectionType)
+		{
+			return this.FirstOrDefault (s => s.Id == id && s.SectionType == sectionType);
+		}
+
+		public SlnSection GetOrCreateSection (string id, SlnSectionType sectionType)
 		{
 			if (id == null)
 				throw new ArgumentNullException ("id");
@@ -626,10 +908,43 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			if (s != null)
 				Remove (s);
 		}
+
+		protected override void InsertItem (int index, SlnSection item)
+		{
+			base.InsertItem (index, item);
+			item.ParentFile = ParentFile;
+		}
+
+		protected override void SetItem (int index, SlnSection item)
+		{
+			base.SetItem (index, item);
+			item.ParentFile = ParentFile;
+		}
+
+		protected override void RemoveItem (int index)
+		{
+			var it = this [index];
+			it.ParentFile = null;
+			base.RemoveItem (index);
+		}
+
+		protected override void ClearItems ()
+		{
+			foreach (var it in this)
+				it.ParentFile = null;
+			base.ClearItems ();
+		}
 	}
 
 	public class SlnPropertySetCollection: Collection<SlnPropertySet>
 	{
+		SlnSection parentSection;
+
+		internal SlnPropertySetCollection (SlnSection parentSection)
+		{
+			this.parentSection = parentSection;
+		}
+
 		public SlnPropertySet GetPropertySet (string id, bool ignoreCase = false)
 		{
 			var sc = ignoreCase ? StringComparison.OrdinalIgnoreCase : StringComparison.Ordinal;
@@ -645,6 +960,32 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			}
 			return ps;
 		}
+
+		protected override void InsertItem (int index, SlnPropertySet item)
+		{
+			base.InsertItem (index, item);
+			item.ParentSection = parentSection;
+		}
+
+		protected override void SetItem (int index, SlnPropertySet item)
+		{
+			base.SetItem (index, item);
+			item.ParentSection = parentSection;
+		}
+
+		protected override void RemoveItem (int index)
+		{
+			var it = this [index];
+			it.ParentSection = null;
+			base.RemoveItem (index);
+		}
+
+		protected override void ClearItems ()
+		{
+			foreach (var it in this)
+				it.ParentSection = null;
+			base.ClearItems ();
+		}
 	}
 
 	class InvalidSolutionFormatException: Exception
@@ -655,7 +996,14 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 
 		public InvalidSolutionFormatException (int line, string msg): base ("Invalid format in line " + line + ": " + msg)
 		{
+			
 		}
 	}
+
+	public enum SlnSectionType
+	{
+		PreProcess,
+		PostProcess
+	}
 }
 
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.Formats.MSBuild/SlnFileFormat.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.Formats.MSBuild/SlnFileFormat.cs
index 6249e8c2c6..8188607c13 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.Formats.MSBuild/SlnFileFormat.cs
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects.Formats.MSBuild/SlnFileFormat.cs
@@ -106,8 +106,6 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 
 		void WriteFileInternal (string file, string sourceFile, Solution solution, bool saveProjects, ProgressMonitor monitor)
 		{
-			string baseDir = Path.GetDirectoryName (sourceFile);
-
 			if (saveProjects) {
 				var items = solution.GetAllSolutionItems ().ToArray ();
 				monitor.BeginTask (items.Length + 1);
@@ -126,7 +124,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			}
 
 			SlnFile sln = new SlnFile ();
-			sln.BaseDirectory = baseDir;
+			sln.FileName = file;
 			if (File.Exists (sourceFile)) {
 				try {
 					sln.Read (sourceFile);
@@ -196,7 +194,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			ICollection<SolutionFolder> folders = solution.RootFolder.GetAllItems<SolutionFolder> ().ToList ();
 			if (folders.Count > 1) {
 				// If folders ==1, that's the root folder
-				var sec = sln.Sections.GetOrCreateSection ("NestedProjects", "preSolution");
+				var sec = sln.Sections.GetOrCreateSection ("NestedProjects", SlnSectionType.PreProcess);
 				foreach (SolutionFolder folder in folders) {
 					if (folder.IsRoot)
 						continue;
@@ -211,7 +209,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 			// Write custom properties for configurations
 			foreach (SolutionConfiguration conf in solution.Configurations) {
 				string secId = "MonoDevelopProperties." + conf.Id;
-				var sec = sln.Sections.GetOrCreateSection (secId, "preSolution");
+				var sec = sln.Sections.GetOrCreateSection (secId, SlnSectionType.PreProcess);
 				solution.WriteConfigurationData (monitor, sec.Properties, conf);
 				if (sec.IsEmpty)
 					sln.Sections.Remove (sec);
@@ -233,12 +231,12 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 					proj.Name = item.Name;
 					proj.FilePath = FileService.NormalizeRelativePath (FileService.AbsoluteToRelativePath (sln.BaseDirectory, item.FileName)).Replace ('/', '\\');
 
-					var sec = proj.Sections.GetOrCreateSection ("MonoDevelopProperties", "preProject");
+					var sec = proj.Sections.GetOrCreateSection ("MonoDevelopProperties", SlnSectionType.PreProcess);
 					sec.SkipIfEmpty = true;
 					folder.ParentSolution.WriteSolutionFolderItemData (monitor, sec.Properties, ce);
 
 					if (item.ItemDependencies.Count > 0) {
-						sec = proj.Sections.GetOrCreateSection ("ProjectDependencies", "postProject");
+						sec = proj.Sections.GetOrCreateSection ("ProjectDependencies", SlnSectionType.PostProcess);
 						sec.Properties.ClearExcept (unknownProjects);
 						foreach (var dep in item.ItemDependencies)
 							sec.Properties.SetValue (dep.ItemId, dep.ItemId);
@@ -254,7 +252,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 					WriteFolderFiles (proj, (SolutionFolder) ce);
 					
 					//Write custom properties
-					var sec = proj.Sections.GetOrCreateSection ("MonoDevelopProperties", "preProject");
+					var sec = proj.Sections.GetOrCreateSection ("MonoDevelopProperties", SlnSectionType.PreProcess);
 					sec.SkipIfEmpty = true;
 					folder.ParentSolution.WriteSolutionFolderItemData (monitor, sec.Properties, ce);
 				}
@@ -267,7 +265,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 		void WriteFolderFiles (SlnProject proj, SolutionFolder folder)
 		{
 			if (folder.Files.Count > 0) {
-				var sec = proj.Sections.GetOrCreateSection ("SolutionItems", "preProject");
+				var sec = proj.Sections.GetOrCreateSection ("SolutionItems", SlnSectionType.PreProcess);
 				sec.Properties.Clear ();
 				foreach (FilePath f in folder.Files) {
 					string relFile = MSBuildProjectService.ToMSBuildPathRelative (folder.ParentSolution.ItemDirectory, f);
@@ -349,151 +347,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 
 			sln.ReadSolutionFolderItemData (monitor, sec.Properties, item);
 		}
-		
-		void WriteDataItem (SlnPropertySet pset, DataItem item)
-		{
-			pset.Clear ();
-			int id = 0;
-			foreach (DataNode val in item.ItemData)
-				WriteDataNode (pset, "", val, ref id);
-		}
-		
-		void WriteDataNode (SlnPropertySet pset, string prefix, DataNode node, ref int id)
-		{
-			string name = node.Name;
-			string newPrefix = prefix.Length > 0 ? prefix + "." + name: name;
-			
-			if (node is DataValue) {
-				DataValue val = (DataValue) node;
-				string value = EncodeString (val.Value);
-				pset.SetValue (newPrefix, value);
-			}
-			else {
-				DataItem it = (DataItem) node;
-				pset.SetValue (newPrefix, "$" + id);
-				newPrefix = "$" + id;
-				id ++;
-				foreach (DataNode cn in it.ItemData)
-					WriteDataNode (pset, newPrefix, cn, ref id);
-			}
-		}
-		
-		string EncodeString (string val)
-		{
-			if (val.Length == 0)
-				return val;
-			
-			int i = val.IndexOfAny (new char[] {'\n','\r','\t'});
-			if (i != -1 || val [0] == '@') {
-				StringBuilder sb = new StringBuilder ();
-				if (i != -1) {
-					int fi = val.IndexOf ('\\');
-					if (fi != -1 && fi < i) i = fi;
-					sb.Append (val.Substring (0,i));
-				} else
-					i = 0;
-				for (int n = i; n < val.Length; n++) {
-					char c = val [n];
-					if (c == '\r')
-						sb.Append (@"\r");
-					else if (c == '\n')
-						sb.Append (@"\n");
-					else if (c == '\t')
-						sb.Append (@"\t");
-					else if (c == '\\')
-						sb.Append (@"\\");
-					else
-						sb.Append (c);
-				}
-				val = "@" + sb.ToString ();
-			}
-			char fc = val [0];
-			char lc = val [val.Length - 1];
-		    if (fc == ' ' || fc == '"' || fc == '$' || lc == ' ')
-				val = "\"" + val + "\"";
-			return val;
-		}
-		
-		string DecodeString (string val)
-		{
-			val = val.Trim (' ', '\t');
-			if (val.Length == 0)
-				return val;
-			if (val [0] == '\"')
-				val = val.Substring (1, val.Length - 2);
-			if (val [0] == '@') {
-				StringBuilder sb = new StringBuilder (val.Length);
-				for (int n = 1; n < val.Length; n++) {
-					char c = val [n];
-					if (c == '\\') {
-						c = val [++n];
-						if (c == 'r') c = '\r';
-						else if (c == 'n') c = '\n';
-						else if (c == 't') c = '\t';
-					}
-					sb.Append (c);
-				}
-				return sb.ToString ();
-			}
-			else
-				return val;
-		}
-		
-		DataItem ReadDataItem (SlnSection sec)
-		{
-			DataItem it = new DataItem ();
-
-			var lines = sec.Properties.ToArray ();
 
-			int lineNum = 0;
-			int lastLine = lines.Length - 1;
-			while (lineNum <= lastLine) {
-				if (!ReadDataNode (it, lines, lastLine, "", ref lineNum))
-					lineNum++;
-			}
-			return it;
-		}
-		
-		bool ReadDataNode (DataItem item, KeyValuePair<string,string>[] lines, int lastLine, string prefix, ref int lineNum)
-		{
-			var s = lines [lineNum];
-			
-			// Check if the line belongs to the current item
-			if (prefix.Length > 0) {
-				if (!s.Key.StartsWith (prefix + "."))
-					return false;
-			} else {
-				if (s.Key.StartsWith ("$"))
-					return false;
-			}
-			
-			string name = s.Key;
-			if (name.Length == 0) {
-				lineNum++;
-				return true;
-			}
-			
-			string value = s.Value;
-			if (value.StartsWith ("$")) {
-				// New item
-				DataItem child = new DataItem ();
-				child.Name = name;
-				lineNum++;
-				while (lineNum <= lastLine) {
-					if (!ReadDataNode (child, lines, lastLine, value, ref lineNum))
-						break;
-				}
-				item.ItemData.Add (child);
-			}
-			else {
-				value = DecodeString (value);
-				DataValue val = new DataValue (name, value);
-				item.ItemData.Add (val);
-				lineNum++;
-			}
-			return true;
-		}
-		
 		string ToSlnConfigurationId (ItemConfiguration configuration)
 		{
 			if (configuration.Platform.Length == 0)
@@ -897,7 +751,7 @@ namespace MonoDevelop.Projects.Formats.MSBuild
 		
 		void LoadNestedProjects (SlnSection sec, IDictionary<string, SolutionFolderItem> entries, ProgressMonitor monitor)
 		{
-			if (sec == null || String.Compare (sec.SectionType, "preSolution", StringComparison.OrdinalIgnoreCase) != 0)
+			if (sec == null || sec.SectionType != SlnSectionType.PreProcess)
 				return;
 
 			foreach (var kvp in sec.Properties) {
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/Solution.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/Solution.cs
index 6f5d3f6484..32cbc108c0 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/Solution.cs
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/Solution.cs
@@ -923,6 +923,7 @@ namespace MonoDevelop.Projects
 		internal void ReadSolution (ProgressMonitor monitor, SlnFile file)
 		{
 			SolutionExtension.OnReadSolution (monitor, file);
+			file.CustomMonoDevelopProperties.ReadObjectProperties (this);
 		}
 
 		/*protected virtual*/ void OnReadSolution (ProgressMonitor monitor, SlnFile file)
@@ -960,6 +961,7 @@ namespace MonoDevelop.Projects
 		/*protected virtual*/ void OnWriteSolution (ProgressMonitor monitor, SlnFile file)
 		{
 			FileFormat.SlnFileFormat.WriteFileInternal (file, this, monitor);
+			file.CustomMonoDevelopProperties.WriteObjectProperties (this);
 		}
 
 		internal void WriteConfigurationData (ProgressMonitor monitor, SlnPropertySet properties, SolutionConfiguration configuration)
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/SolutionDataSectionAttribute.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/SolutionDataSectionAttribute.cs
new file mode 100644
index 0000000000..a772ae4f2c
--- /dev/null
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/SolutionDataSectionAttribute.cs
@@ -0,0 +1,44 @@
+//
+// SolutionDataSectionAttribute.cs
+//
+// Author:
+//       Lluis Sanchez Gual <lluis@xamarin.com>
+//
+// Copyright (c) 2015 Xamarin, Inc (http://www.xamarin.com)
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+using MonoDevelop.Projects.Formats.MSBuild;
+
+namespace MonoDevelop.Projects
+{
+	public class SolutionDataSectionAttribute: Attribute
+	{
+		public SolutionDataSectionAttribute (string sectionName, SlnSectionType processOrder = SlnSectionType.PostProcess)
+		{
+			SectionName = sectionName;
+			ProcessOrder = processOrder;
+		}
+
+		public string SectionName { get; set; }
+
+		public SlnSectionType ProcessOrder { get; set; }
+	}
+}
+
diff --git a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/SolutionExtension.cs b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/SolutionExtension.cs
index 5126eb308d..545f2f8651 100644
--- a/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/SolutionExtension.cs
+++ b/main/src/core/MonoDevelop.Core/MonoDevelop.Projects/SolutionExtension.cs
@@ -88,7 +88,20 @@ namespace MonoDevelop.Projects
 
 		internal protected virtual void OnReadSolution (ProgressMonitor monitor, SlnFile file)
 		{
+			var secAttribute = (SolutionDataSectionAttribute) Attribute.GetCustomAttribute (GetType(), typeof(SolutionDataSectionAttribute));
+			if (secAttribute != null && secAttribute.ProcessOrder == SlnSectionType.PreProcess) {
+				var sec = file.Sections.GetSection (secAttribute.SectionName, SlnSectionType.PreProcess);
+				if (sec != null)
+					sec.Properties.ReadObjectProperties (this);
+			}
+
 			next.OnReadSolution (monitor, file);
+
+			if (secAttribute != null && secAttribute.ProcessOrder == SlnSectionType.PostProcess) {
+				var sec = file.Sections.GetSection (secAttribute.SectionName, SlnSectionType.PostProcess);
+				if (sec != null)
+					sec.Properties.ReadObjectProperties (this);
+			}
 		}
 
 		internal protected virtual void OnReadSolutionFolderItemData (ProgressMonitor monitor, SlnPropertySet properties, SolutionFolderItem item)
@@ -103,7 +116,20 @@ namespace MonoDevelop.Projects
 
 		internal protected virtual void OnWriteSolution (ProgressMonitor monitor, SlnFile file)
 		{
+			var secAttribute = (SolutionDataSectionAttribute) Attribute.GetCustomAttribute (GetType(), typeof(SolutionDataSectionAttribute));
+			if (secAttribute != null && secAttribute.ProcessOrder == SlnSectionType.PreProcess) {
+				var sec = file.Sections.GetOrCreateSection (secAttribute.SectionName, SlnSectionType.PreProcess);
+				sec.SkipIfEmpty = true;
+				sec.Properties.WriteObjectProperties (this);
+			}
+
 			next.OnWriteSolution (monitor, file);
+
+			if (secAttribute != null && secAttribute.ProcessOrder == SlnSectionType.PostProcess) {
+				var sec = file.Sections.GetOrCreateSection (secAttribute.SectionName, SlnSectionType.PostProcess);
+				sec.SkipIfEmpty = true;
+				sec.Properties.WriteObjectProperties (this);
+			}
 		}
 
 		internal protected virtual void OnWriteSolutionFolderItemData (ProgressMonitor monitor, SlnPropertySet properties, SolutionFolderItem item)
diff --git a/main/tests/UnitTests/MonoDevelop.Projects/PolicyTests.cs b/main/tests/UnitTests/MonoDevelop.Projects/PolicyTests.cs
new file mode 100644
index 0000000000..3a5e23abf4
--- /dev/null
+++ b/main/tests/UnitTests/MonoDevelop.Projects/PolicyTests.cs
@@ -0,0 +1,37 @@
+//
+// PolicyTests.cs
+//
+// Author:
+//       Lluis Sanchez Gual <lluis@xamarin.com>
+//
+// Copyright (c) 2015 Xamarin, Inc (http://www.xamarin.com)
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+using NUnit.Framework;
+using UnitTests;
+
+namespace MonoDevelop.Projects
+{
+	[TestFixture]
+	public class PolicyTests: TestBase
+	{
+	}
+}
+
diff --git a/main/tests/UnitTests/MonoDevelop.Projects/SolutionTests.cs b/main/tests/UnitTests/MonoDevelop.Projects/SolutionTests.cs
index 3f50885211..4b288fe6f4 100644
--- a/main/tests/UnitTests/MonoDevelop.Projects/SolutionTests.cs
+++ b/main/tests/UnitTests/MonoDevelop.Projects/SolutionTests.cs
@@ -35,6 +35,8 @@ using MonoDevelop.Core;
 using MonoDevelop.Projects.Formats.MSBuild;
 using MonoDevelop.Core.ProgressMonitoring;
 using System.Threading.Tasks;
+using MonoDevelop.Core.Serialization;
+using MonoDevelop.Projects.Extensions;
 
 namespace MonoDevelop.Projects
 {
@@ -894,6 +896,103 @@ namespace MonoDevelop.Projects
 			Assert.IsTrue (p.ItemDependencies.Contains (lib2Reloaded));
 			Assert.AreEqual (1, p.ItemDependencies.Count);
 		}
+
+		[Test]
+		public async Task WriteCustomData ()
+		{
+			var en = new CustomSolutionItemNode<TestSolutionExtension> ();
+			WorkspaceObject.RegisterCustomExtension (en);
+			try {
+				string solFile = Util.GetSampleProject ("solution-custom-data", "custom-data.sln");
+
+				var sol = new Solution ();
+				var ext = sol.GetService<TestSolutionExtension> ();
+				Assert.NotNull (ext);
+				ext.Prop1 = "one";
+				ext.Prop2 = "two";
+				ext.Extra = new ComplexSolutionData {
+					Prop3 = "three",
+					Prop4 = "four"
+				};
+				var savedFile = solFile + ".saved.sln";
+				await sol.SaveAsync (savedFile, Util.GetMonitor ());
+				Assert.AreEqual (File.ReadAllText (solFile), File.ReadAllText (savedFile));
+			} finally {
+				WorkspaceObject.UnregisterCustomExtension (en);
+			}
+		}
+
+		[Test]
+		public async Task ReadCustomData ()
+		{
+			var en = new CustomSolutionItemNode<TestSolutionExtension> ();
+			WorkspaceObject.RegisterCustomExtension (en);
+			try {
+				string solFile = Util.GetSampleProject ("solution-custom-data", "custom-data.sln");
+				var sol = (Solution) await Services.ProjectService.ReadWorkspaceItem (Util.GetMonitor (), solFile);
+
+				var ext = sol.GetService<TestSolutionExtension> ();
+				Assert.NotNull (ext);
+				Assert.AreEqual ("one", ext.Prop1);
+				Assert.AreEqual ("two", ext.Prop2);
+				Assert.NotNull (ext.Extra);
+				Assert.AreEqual ("three", ext.Extra.Prop3);
+				Assert.AreEqual ("four", ext.Extra.Prop4);
+			} finally {
+				WorkspaceObject.UnregisterCustomExtension (en);
+			}
+		}
+
+		[Test]
+		public async Task KeepUnknownCustomData ()
+		{
+			var en = new CustomSolutionItemNode<TestSolutionExtension> ();
+			WorkspaceObject.RegisterCustomExtension (en);
+			try {
+				FilePath solFile = Util.GetSampleProject ("solution-custom-data", "custom-data-keep-unknown.sln");
+				var sol = (Solution) await Services.ProjectService.ReadWorkspaceItem (Util.GetMonitor (), solFile);
+
+				var ext = sol.GetService<TestSolutionExtension> ();
+				ext.Prop1 = "one-mod";
+				ext.Prop2 = "";
+				ext.Extra.Prop3 = "three-mod";
+				ext.Extra.Prop4 = "";
+
+				var refFile = solFile.ParentDirectory.Combine ("custom-data-keep-unknown.sln.saved");
+
+				await sol.SaveAsync (Util.GetMonitor ());
+
+				Assert.AreEqual (File.ReadAllText (refFile), File.ReadAllText (sol.FileName));
+
+			} finally {
+				WorkspaceObject.UnregisterCustomExtension (en);
+			}
+		}
+
+		[Test]
+		public async Task RemoveCustomData ()
+		{
+			var en = new CustomSolutionItemNode<TestSolutionExtension> ();
+			WorkspaceObject.RegisterCustomExtension (en);
+			try {
+				FilePath solFile = Util.GetSampleProject ("solution-custom-data", "custom-data.sln");
+				var sol = (Solution) await Services.ProjectService.ReadWorkspaceItem (Util.GetMonitor (), solFile);
+
+				var ext = sol.GetService<TestSolutionExtension> ();
+				ext.Prop1 = "xx";
+				ext.Prop2 = "";
+				ext.Extra = null;
+
+				var refFile = solFile.ParentDirectory.Combine ("no-custom-data.sln");
+
+				await sol.SaveAsync (Util.GetMonitor ());
+
+				Assert.AreEqual (File.ReadAllText (refFile), File.ReadAllText (sol.FileName));
+
+			} finally {
+				WorkspaceObject.UnregisterCustomExtension (en);
+			}
+		}
 	}
 
 	class SomeItem: SolutionItem
@@ -931,4 +1030,34 @@ namespace MonoDevelop.Projects
 			UnboundEvents++;
 		}
 	}
+
+	class CustomSolutionItemNode<T>: ProjectModelExtensionNode where T:new()
+	{
+		public override object CreateInstance ()
+		{
+			return new T ();
+		}
+	}
+
+	[SolutionDataSection ("TestData")]
+	class TestSolutionExtension: SolutionExtension
+	{
+		[ItemProperty ("prop1", DefaultValue = "xx")]
+		public string Prop1 { get; set; }
+
+		[ItemProperty ("prop2", DefaultValue = "")]
+		public string Prop2 { get; set; }
+
+		[ItemProperty ("extra")]
+		public ComplexSolutionData Extra { get; set; }
+	}
+
+	class ComplexSolutionData
+	{
+		[ItemProperty ("prop3")]
+		public string Prop3 { get; set; }
+
+		[ItemProperty ("prop4", DefaultValue = "")]
+		public string Prop4 { get; set; }
+	}
 }
diff --git a/main/tests/UnitTests/UnitTests.csproj b/main/tests/UnitTests/UnitTests.csproj
index 194233df60..b9b03e3275 100644
--- a/main/tests/UnitTests/UnitTests.csproj
+++ b/main/tests/UnitTests/UnitTests.csproj
@@ -270,6 +270,7 @@
     <Compile Include="MonoDevelop.Projects\StringTagTests.cs" />
     <Compile Include="MonoDevelop.Ide.Templates\FileTemplateParserTests.cs" />
     <Compile Include="MonoDevelop.Ide.Templates\ProjectCreateInformationTests.cs" />
+    <Compile Include="MonoDevelop.Projects\PolicyTests.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <Import Project="..\..\md.targets" />