Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Web/UI/WebParts/WebPartTracker.cs

@@ -0,0 +1,67 @@
+//------------------------------------------------------------------------------
+// <copyright file="WebPartTracker.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+namespace System.Web.UI.WebControls.WebParts {
+
+    using System;
+    using System.Collections;
+    using System.ComponentModel;
+    using System.Diagnostics;
+    using System.Drawing.Design;
+    using System.Web;
+    using System.Web.UI;
+
+    public sealed class WebPartTracker : IDisposable {
+        private bool _disposed;
+        private WebPart _webPart;
+        private ProviderConnectionPoint _providerConnectionPoint;
+
+        public WebPartTracker(WebPart webPart, ProviderConnectionPoint providerConnectionPoint) {
+            if (webPart == null) {
+                throw new ArgumentNullException("webPart");
+            }
+
+            if (providerConnectionPoint == null) {
+                throw new ArgumentNullException("providerConnectionPoint");
+            }
+
+            if (providerConnectionPoint.ControlType != webPart.GetType()) {
+                throw new ArgumentException(SR.GetString(SR.WebPartManager_InvalidConnectionPoint), "providerConnectionPoint");
+            }
+
+            _webPart = webPart;
+            _providerConnectionPoint = providerConnectionPoint;
+
+            if (++Count > 1) {
+                webPart.SetConnectErrorMessage(SR.GetString(SR.WebPartTracker_CircularConnection, _providerConnectionPoint.DisplayName));
+            }
+        }
+
+        public bool IsCircularConnection {
+            get {
+                return (Count > 1);
+            }
+        }
+
+        private int Count {
+            get {
+                int count;
+                _webPart.TrackerCounter.TryGetValue(_providerConnectionPoint, out count);
+                return count;
+            }
+            set {
+                _webPart.TrackerCounter[_providerConnectionPoint] = value;
+            }
+        }
+
+        void IDisposable.Dispose() {
+            if (!_disposed) {
+                Debug.Assert(Count >= 1);
+                Count--;
+                _disposed = true;
+            }
+        }
+    }
+}