Preserve Documents debug info

Mono.Cecil.Cil/PortablePdb.cs

@@ -119,6 +119,7 @@ static int ReadInt32 (byte [] bytes, int start)
 		void ReadModule ()
 		{
 			module.custom_infos = debug_reader.GetCustomDebugInformation (module);
+			module.documents = debug_reader.GetDocuments ();
 		}
 
 		public MethodDebugInformation Read (MethodDefinition method)
@@ -295,6 +296,7 @@ internal PortablePdbWriter (MetadataBuilder pdb_metadata, ModuleDefinition modul
 				this.pdb_metadata.metadata_builder = this.module_metadata;
 
 			pdb_metadata.AddCustomDebugInformations (module);
+			pdb_metadata.AddDocuments (module);
 		}
 
 		internal PortablePdbWriter (MetadataBuilder pdb_metadata, ModuleDefinition module, ImageWriter writer, Disposable<Stream> final_stream)

Mono.Cecil/AssemblyReader.cs

@@ -2834,6 +2834,13 @@ void InitializeDocuments ()
 			}
 		}
 
+		internal Collection<Document> GetDocuments ()
+		{
+			InitializeDocuments ();
+
+			return new Collection<Document> (metadata.Documents);
+		}
+
 		public Collection<SequencePoint> ReadSequencePoints (MethodDefinition method)
 		{
 			InitializeDocuments ();

Mono.Cecil/AssemblyWriter.cs

@@ -2019,6 +2019,17 @@ void AddSecurityDeclarations (ISecurityDeclarationProvider owner)
 			}
 		}
 
+		internal void AddDocuments (ModuleDefinition module)
+		{
+			if (module.HasDocuments)
+			{
+				var documents = module.Documents;
+				for (int i = 0; i < documents.Count; i++) {
+					GetDocumentToken (documents[i]);
+				}
+			}
+		}
+
 		MetadataToken GetMemberRefToken (MemberReference member)
 		{
 			var row = CreateMemberRefRow (member);

Mono.Cecil/ModuleDefinition.cs

@@ -290,6 +290,7 @@ public sealed class ModuleDefinition : ModuleReference, ICustomAttributeProvider
 		TypeDefinitionCollection types;
 
 		internal Collection<CustomDebugInformation> custom_infos;
+		internal Collection<Document> documents;
 
 		internal MetadataBuilder metadata_builder;
 
@@ -601,6 +602,21 @@ public Collection<CustomDebugInformation> CustomDebugInformations {
 			}
 		}
 
+		internal bool HasDocuments {
+			get {
+				return documents != null && documents.Count > 0;
+			}
+		}
+
+		internal Collection<Document> Documents {
+			get {
+				if (documents == null)
+					Interlocked.CompareExchange (ref documents, new Collection<Document> (), null);
+
+				return documents;
+			}
+		}
+
 		internal ModuleDefinition ()
 		{
 			this.MetadataSystem = new MetadataSystem ();

Test/Mono.Cecil.Tests/PortablePdbTests.cs

@@ -15,6 +15,19 @@ namespace Mono.Cecil.Tests {
 	[TestFixture]
 	public class PortablePdbTests : BaseTestFixture {
 
+		[Test]
+		public void Documents ()
+		{
+		    TestModule ("DocumentsTestTarget.dll", module => {
+		        var documents = module.Documents;
+		        Assert.AreEqual(1, documents.Count);
+				var document = documents[0];
+				Assert.IsNotNull (document);
+				Assert.AreEqual ("/_/DocumentsTestTarget.cs", document.Url);
+		        Assert.AreEqual (DocumentLanguage.CSharp, document.Language);
+		    }, symbolReaderProvider: typeof(PortablePdbReaderProvider), symbolWriterProvider: typeof(PortablePdbWriterProvider));
+		}
+
 		[Test]
 		public void SequencePoints ()
 		{