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                 [ReliabilityContract (Consistency.WillNotCorruptState, Cer.MayFail)]
  43                 [DebuggerNonUserCode]
  44                 public static string RaiseContractFailedEvent (ContractFailureKind failureKind, string userMessage, string conditionText, Exception innerException)
  45                 {
  46
  47                         StringBuilder msg = new StringBuilder (60);
  48                         switch (failureKind) {
  49                         case ContractFailureKind.Assert:
  50                                 msg.Append ("Assertion failed");
  51                                 break;
  52                         case ContractFailureKind.Assume:
  53                                 msg.Append ("Assumption failed");
  54                                 break;
  55                         case ContractFailureKind.Invariant:
  56                                 msg.Append ("Invariant failed");
  57                                 break;
  58                         case ContractFailureKind.Postcondition:
  59                                 msg.Append ("Postcondition failed");
  60                                 break;
  61                         case ContractFailureKind.PostconditionOnException:
  62                                 msg.Append ("Postcondition failed after throwing an exception");
  63                                 break;
  64                         case ContractFailureKind.Precondition:
  65                                 msg.Append ("Precondition failed");
  66                                 break;
  67                         default:
  68                                 throw new NotSupportedException ("Not supported: " + failureKind);
  69                         }
  70                         if (conditionText != null) {
  71                                 msg.Append (": ");
  72                                 msg.Append (conditionText);
  73                         } else {
  74                                 msg.Append ('.');
  75                         }
  76                         if (userMessage != null) {
  77                                 msg.Append ("  ");
  78                                 msg.Append (userMessage);
  79                         }
  80                         string msgString = msg.ToString ();
  81
  82                         Exception handlerException = null;
  83                         bool unwind = false, handled = false;
  84
  85                         var contractFailed = Contract.InternalContractFailedEvent;
  86                         if (contractFailed != null) {
  87                                 // Execute all event handlers
  88                                 var handlers = contractFailed.GetInvocationList ();
  89                                 var e = new ContractFailedEventArgs (failureKind, msgString, conditionText, innerException);
  90                                 foreach (var handler in handlers) {
  91                                         try {
  92                                                 handler.DynamicInvoke (null, e);
  93                                         } catch (Exception ex) {
  94                                                 e.SetUnwind ();
  95                                                 // If multiple handlers throw an exception then the specification states that it
  96                                                 // is undetermined which one becomes the InnerException.
  97                                                 handlerException = ex.InnerException;
  98                                         }
  99                                 }
 100                                 unwind = e.Unwind;
 101                                 handled = e.Handled;
 102                         }
 103
 104                         if (unwind) {
 105                                 Exception ex = innerException ?? handlerException;
 106                                 throw new ContractException (msgString, failureKind, conditionText, userMessage, ex);
 107                         }
 108
 109                         return handled ? null : msgString;
 110                 }
 111
 112                 [ReliabilityContract (Consistency.WillNotCorruptState, Cer.Success)]
 113                 [DebuggerNonUserCode]
 114                 public static void TriggerFailure (ContractFailureKind kind, string displayMessage, string userMessage, string conditionText, Exception innerException)
 115                 {
 116                         StringBuilder msg = new StringBuilder (50);
 117
 118                         if (conditionText != null) {
 119                                 msg.Append ("Expression: ");
 120                                 msg.AppendLine (conditionText);
 121                         }
 122                         msg.Append ("Description: ");
 123                         if (displayMessage != null) {
 124                                 msg.Append (displayMessage);
 125                         }
 126                         if (Environment.UserInteractive) {
 127                                 // FIXME: This should trigger an assertion.
 128                                 // But code will never get here at the moment, as Environment.UserInteractive currently
 129                                 // always returns false.
 130                                 throw new ContractShouldAssertException (msg.ToString ());
 131                         } else {
 132                                 // Note that FailFast() currently throws a NotImplementedException()
 133                                 Environment.FailFast(msg.ToString()/*, new ExecutionEngineException()*/);
 134                         }
 135                 }
 136
 137         }
 138
 139 }
 140
 141 #endif