mcs/class/corlib/System.Diagnostics.Contracts.Internal/ContractHelper.cs

   1 //
   2 // System.Diagnostics.Contracts.Internal.ContractHelper.cs
   3 //
   4 // Authors:
   5 //    Chris Bacon (chrisbacon76@gmail.com)
   6 //
   7 // Copyright 2010 Novell (http://www.novell.com)
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28
  29 #if NET_4_0 || NET_2_1
  30
  31 using System;
  32 using System.Text;
  33 using System.Reflection;
  34 using System.Runtime.ConstrainedExecution;
  35
  36 namespace System.Diagnostics.Contracts.Internal
  37 {
  38 #if NET_4_5
  39         [Obsolete ("Type has been moved to System.Runtime.CompilerServices")]
  40 #endif
  41         public static class ContractHelper
  42         {
  43 #if MOONLIGHT
  44                 const string SystemWindowsBrowser = ", System.Windows.Browser, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e";
  45                 const string HtmlPage = "System.Windows.Browser.HtmlPage" + SystemWindowsBrowser;
  46                 const string HtmlWindow = "System.Windows.Browser.HtmlWindow" + SystemWindowsBrowser;
  47                 static MethodInfo alert;
  48                 static object window;
  49
  50                 static ContractHelper ()
  51                 {
  52                         Type htmlpage = Type.GetType (HtmlPage);
  53                         MethodInfo get_window = htmlpage.GetMethod ("get_Window", BindingFlags.Static | BindingFlags.Public);
  54                         window = get_window.Invoke (null, null);
  55                         Type htmlwindow = Type.GetType (HtmlWindow);
  56                         alert = htmlwindow.GetMethod ("Alert", BindingFlags.Instance | BindingFlags.Public);
  57                 }
  58 #endif
  59
  60                 [ReliabilityContract (Consistency.WillNotCorruptState, Cer.Success)]
  61                 [DebuggerNonUserCode]
  62                 public static string RaiseContractFailedEvent (ContractFailureKind failureKind, string userMessage, string conditionText, Exception innerException)
  63                 {
  64
  65                         StringBuilder msg = new StringBuilder (60);
  66                         switch (failureKind) {
  67                         case ContractFailureKind.Assert:
  68                                 msg.Append ("Assertion failed");
  69                                 break;
  70                         case ContractFailureKind.Assume:
  71                                 msg.Append ("Assumption failed");
  72                                 break;
  73                         case ContractFailureKind.Invariant:
  74                                 msg.Append ("Invariant failed");
  75                                 break;
  76                         case ContractFailureKind.Postcondition:
  77                                 msg.Append ("Postcondition failed");
  78                                 break;
  79                         case ContractFailureKind.PostconditionOnException:
  80                                 msg.Append ("Postcondition failed after throwing an exception");
  81                                 break;
  82                         case ContractFailureKind.Precondition:
  83                                 msg.Append ("Precondition failed");
  84                                 break;
  85                         default:
  86                                 throw new NotSupportedException ("Not supported: " + failureKind);
  87                         }
  88                         if (conditionText != null) {
  89                                 msg.Append (": ");
  90                                 msg.Append (conditionText);
  91                         } else {
  92                                 msg.Append ('.');
  93                         }
  94                         if (userMessage != null) {
  95                                 msg.Append ("  ");
  96                                 msg.Append (userMessage);
  97                         }
  98                         string msgString = msg.ToString ();
  99
 100                         Exception handlerException = null;
 101                         bool unwind = false, handled = false;
 102
 103                         var contractFailed = Contract.InternalContractFailedEvent;
 104                         if (contractFailed != null) {
 105                                 // Execute all event handlers
 106                                 var handlers = contractFailed.GetInvocationList ();
 107                                 var e = new ContractFailedEventArgs (failureKind, msgString, conditionText, innerException);
 108                                 foreach (var handler in handlers) {
 109                                         try {
 110                                                 handler.DynamicInvoke (null, e);
 111                                         } catch (Exception ex) {
 112                                                 e.SetUnwind ();
 113                                                 // If multiple handlers throw an exception then the specification states that it
 114                                                 // is undetermined which one becomes the InnerException.
 115                                                 handlerException = ex.InnerException;
 116                                         }
 117                                 }
 118                                 unwind = e.Unwind;
 119                                 handled = e.Handled;
 120                         }
 121
 122                         if (unwind) {
 123                                 Exception ex = innerException ?? handlerException;
 124                                 throw new ContractException (msgString, failureKind, conditionText, userMessage, ex);
 125                         }
 126
 127                         return handled ? null : msgString;
 128                 }
 129
 130                 [ReliabilityContract (Consistency.WillNotCorruptState, Cer.Success)]
 131                 [DebuggerNonUserCode]
 132                 public static void TriggerFailure (ContractFailureKind kind, string displayMessage, string userMessage, string conditionText, Exception innerException)
 133                 {
 134                         StringBuilder msg = new StringBuilder (50);
 135
 136                         if (conditionText != null) {
 137                                 msg.Append ("Expression: ");
 138                                 msg.AppendLine (conditionText);
 139                         }
 140                         msg.Append ("Description: ");
 141                         if (displayMessage != null) {
 142                                 msg.Append (displayMessage);
 143                         }
 144 #if MOONLIGHT
 145                         // Silverlight shows a dialog that let you Abort (kill process/browser), Retry or Ignore
 146                         // Moonlight will simply warn and ignore (at least until FailFast is implemented)
 147                         // using reflection into System.Windows.Browser to popup an browser alert
 148                         alert.Invoke (window, new object [] { msg.ToString () });
 149 #else
 150                         if (Environment.UserInteractive) {
 151                                 // FIXME: This should trigger an assertion.
 152                                 // But code will never get here at the moment, as Environment.UserInteractive currently
 153                                 // always returns false.
 154                                 throw new ContractShouldAssertException (msg.ToString ());
 155                         } else {
 156                                 // Note that FailFast() currently throws a NotImplementedException()
 157                                 Environment.FailFast(msg.ToString()/*, new ExecutionEngineException()*/);
 158                         }
 159 #endif
 160                 }
 161
 162         }
 163
 164 }
 165
 166 #endif