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