Demangle Anonymous Function Names

Demangle compiler generated function names for anonymous functions and
replace with something more readable.

Change:

    <BeginInvokeAsynchronousActionMethod>b__36
to:

    BeginInvokeAsynchronousActionMethod { <lambda> }

Fixes #147

src/app/SharpRaven/Data/ExceptionFrame.cs

@@ -82,7 +82,8 @@ public ExceptionFrame(StackFrame frame)
             LineNumber = lineNo;
             ColumnNumber = frame.GetFileColumnNumber();
             InApp = !IsSystemModuleName(Module);
-            DemangleFunctionName();
+            DemangleAsyncFunctionName();
+            DemangleAnonymousFunction();
         }
 
 
@@ -244,7 +245,7 @@ private static bool IsSystemModuleName(string moduleName)
         /// names that appears in the Sentry UI will match the function and module
         /// names in the original source-code.
         /// </para>
-        private void DemangleFunctionName()
+        private void DemangleAsyncFunctionName()
         {
             if (Module == null || Function != "MoveNext")
             {
@@ -266,5 +267,30 @@ private void DemangleFunctionName()
                 Function = match.Groups[2].Value;
             }
         }
+
+        /// <summary>
+        /// Clean up function names for anonymous lambda calls.
+        /// </summary>
+        private void DemangleAnonymousFunction()
+        {
+            if (Function == null)
+            {
+                return;
+            }
+
+            // Search for the function name in angle brackets followed by b__<digits/letters>.
+            //
+            // Change:
+            //   <BeginInvokeAsynchronousActionMethod>b__36
+            // to:
+            //   BeginInvokeAsynchronousActionMethod { <lambda> }
+
+            var mangled = @"^<(\w*)>b__\w+$";
+            var match = Regex.Match(Function, mangled);
+            if (match.Success && match.Groups.Count == 2)
+            {
+                Function = match.Groups[1].Value + " { <lambda> }";
+            }
+        }
     }
 }

src/tests/SharpRaven.UnitTests/Data/ExceptionFrameTests.cs

@@ -133,5 +133,16 @@ public void Constructor_Demangles_Function_Names()
             Assert.AreEqual(frame.Function, "EditVrByJson");
             Assert.AreEqual(frame.Module, "Flipdish.Domain.DomainModel.Services.RestaurantService");
         }
+
+        [Test]
+        public void Contructor_Demangles_Lambdas()
+        {
+            var module = "Example.Module";
+
+            Assert.AreEqual("BeginInvokeAsynchronousActionMethod { <lambda> }", MockStackFrame(module, "<BeginInvokeAsynchronousActionMethod>b__36").Function);
+            Assert.AreEqual("InvokeActionMethodFilterAsynchronouslyRecursive { <lambda> }", MockStackFrame(module, "<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d").Function);
+            Assert.AreEqual("BeginInvokeAction { <lambda> }", MockStackFrame(module, "<BeginInvokeAction>b__1e").Function);
+
+        }
     }
 }