Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Activities/System/Activities/Debugger/VirtualStackFrame.cs

@@ -0,0 +1,51 @@
+//-----------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//-----------------------------------------------------------------------------
+
+namespace System.Activities.Debugger
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Diagnostics;
+    using System.Runtime;
+
+    // A virtual callstack frame for the interpretter.
+    // This is created by calls to EnterState and LeaveState.
+    // This is explictly not named "StackFrame" so that it's not confused with 
+    // System.Diagnostics.StackFrame.
+    [DebuggerNonUserCode]
+    [Fx.Tag.XamlVisible(false)]
+    public class VirtualStackFrame
+    {
+        State state;
+        IDictionary<string, object> locals;
+
+        public VirtualStackFrame(State state, IDictionary<string, object> locals)
+        {
+            this.state = state;
+            this.locals = locals;
+        }
+
+        public VirtualStackFrame(State state)
+            : this(state, null)
+        {
+            Fx.Assert(state.NumberOfEarlyLocals == 0, "should start with empty locals");
+        }
+
+        public State State
+        {
+            get { return this.state; }
+        }
+
+        // All locals (both early-bound and late-bound) for this frame.
+        public IDictionary<string, object> Locals
+        {
+            get { return this.locals; }
+        }
+
+        public override string ToString()
+        {
+            return this.state.ToString();
+        }
+    }
+}