mcs/class/corlib/System.Runtime.CompilerServices/ContractHelper.cs

   1 //
   2 // 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_5
  30
  31 using System;
  32 using System.Text;
  33 using System.Reflection;
  34 using System.Runtime.ConstrainedExecution;
  35 using System.Diagnostics.Contracts;
  36 using System.Diagnostics;
  37
  38 namespace System.Runtime.CompilerServices
  39 {
  40         public static class ContractHelper
  41         {
  42 #if MOONLIGHT
  43                 const string SystemWindowsBrowser = ", System.Windows.Browser, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e";
  44                 const string HtmlPage = "System.Windows.Browser.HtmlPage" + SystemWindowsBrowser;
  45                 const string HtmlWindow = "System.Windows.Browser.HtmlWindow" + SystemWindowsBrowser;
  46                 static MethodInfo alert;
  47                 static object window;
  48
  49                 static ContractHelper ()
  50                 {
  51                         Type htmlpage = Type.GetType (HtmlPage);
  52                         MethodInfo get_window = htmlpage.GetMethod ("get_Window", BindingFlags.Static | BindingFlags.Public);
  53                         window = get_window.Invoke (null, null);
  54                         Type htmlwindow = Type.GetType (HtmlWindow);
  55                         alert = htmlwindow.GetMethod ("Alert", BindingFlags.Instance | BindingFlags.Public);
  56                 }
  57 #endif
  58
  59                 [ReliabilityContract (Consistency.WillNotCorruptState, Cer.MayFail)]
  60                 [DebuggerNonUserCode]
  61                 public static string RaiseContractFailedEvent (ContractFailureKind failureKind, string userMessage, string conditionText, Exception innerException)
  62                 {
  63
  64                         StringBuilder msg = new StringBuilder (60);
  65                         switch (failureKind) {
  66                         case ContractFailureKind.Assert:
  67                                 msg.Append ("Assertion failed");
  68                                 break;
  69                         case ContractFailureKind.Assume:
  70                                 msg.Append ("Assumption failed");
  71                                 break;
  72                         case ContractFailureKind.Invariant:
  73                                 msg.Append ("Invariant failed");
  74                                 break;
  75                         case ContractFailureKind.Postcondition:
  76                                 msg.Append ("Postcondition failed");
  77                                 break;
  78                         case ContractFailureKind.PostconditionOnException:
  79                                 msg.Append ("Postcondition failed after throwing an exception");
  80                                 break;
  81                         case ContractFailureKind.Precondition:
  82                                 msg.Append ("Precondition failed");
  83                                 break;
  84                         default:
  85                                 throw new NotSupportedException ("Not supported: " + failureKind);
  86                         }
  87                         if (conditionText != null) {
  88                                 msg.Append (": ");
  89                                 msg.Append (conditionText);
  90                         } else {
  91                                 msg.Append ('.');
  92                         }
  93                         if (userMessage != null) {
  94                                 msg.Append ("  ");
  95                                 msg.Append (userMessage);
  96                         }
  97                         string msgString = msg.ToString ();
  98
  99                         Exception handlerException = null;
 100                         bool unwind = false, handled = false;
 101
 102                         var contractFailed = Contract.InternalContractFailedEvent;
 103                         if (contractFailed != null) {
 104                                 // Execute all event handlers
 105                                 var handlers = contractFailed.GetInvocationList ();
 106                                 var e = new ContractFailedEventArgs (failureKind, msgString, conditionText, innerException);
 107                                 foreach (var handler in handlers) {
 108                                         try {
 109                                                 handler.DynamicInvoke (null, e);
 110                                         } catch (Exception ex) {
 111                                                 e.SetUnwind ();
 112                                                 // If multiple handlers throw an exception then the specification states that it
 113                                                 // is undetermined which one becomes the InnerException.
 114                                                 handlerException = ex.InnerException;
 115                                         }
 116                                 }
 117                                 unwind = e.Unwind;
 118                                 handled = e.Handled;
 119                         }
 120
 121                         if (unwind) {
 122                                 Exception ex = innerException ?? handlerException;
 123                                 throw new ContractException (msgString, failureKind, conditionText, userMessage, ex);
 124                         }
 125
 126                         return handled ? null : msgString;
 127                 }
 128
 129                 [ReliabilityContract (Consistency.WillNotCorruptState, Cer.Success)]
 130                 [DebuggerNonUserCode]
 131                 public static void TriggerFailure (ContractFailureKind kind, string displayMessage, string userMessage, string conditionText, Exception innerException)
 132                 {
 133                         StringBuilder msg = new StringBuilder (50);
 134
 135                         if (conditionText != null) {
 136                                 msg.Append ("Expression: ");
 137                                 msg.AppendLine (conditionText);
 138                         }
 139                         msg.Append ("Description: ");
 140                         if (displayMessage != null) {
 141                                 msg.Append (displayMessage);
 142                         }
 143 #if MOONLIGHT
 144                         // Silverlight shows a dialog that let you Abort (kill process/browser), Retry or Ignore
 145                         // Moonlight will simply warn and ignore (at least until FailFast is implemented)
 146                         // using reflection into System.Windows.Browser to popup an browser alert
 147                         alert.Invoke (window, new object [] { msg.ToString () });
 148 #else
 149                         if (Environment.UserInteractive) {
 150                                 // FIXME: This should trigger an assertion.
 151                                 // But code will never get here at the moment, as Environment.UserInteractive currently
 152                                 // always returns false.
 153                                 throw new ContractShouldAssertException (msg.ToString ());
 154                         } else {
 155                                 // Note that FailFast() currently throws a NotImplementedException()
 156                                 Environment.FailFast(msg.ToString()/*, new ExecutionEngineException()*/);
 157                         }
 158 #endif
 159                 }
 160
 161         }
 162
 163 }
 164
 165 #endif