mcs/class/Mono.CodeContracts/Mono.CodeContracts.Static.Proving/BasicFacts.cs

   1 //
   2 // BasicFacts.cs
   3 //
   4 // Authors:
   5 //      Alexander Chebaturkin (chebaturkin@gmail.com)
   6 //
   7 // Copyright (C) 2011 Alexander Chebaturkin
   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 using System;
  30 using Mono.CodeContracts.Static.Analysis;
  31 using Mono.CodeContracts.Static.ControlFlow;
  32 using Mono.CodeContracts.Static.DataStructures;
  33
  34 namespace Mono.CodeContracts.Static.Proving {
  35         class BasicFacts<Expression, Variable> : IFactQuery<BoxedExpression, Variable> {
  36                 protected IExpressionContextProvider<Expression, Variable> ContextProvider;
  37                 protected IFactBase<Variable> FactBase;
  38                 protected Predicate<APC> isUnreachable;
  39
  40                 public BasicFacts (IExpressionContextProvider<Expression, Variable> contextProvider, IFactBase<Variable> factBase, Predicate<APC> isUnreachable)
  41                 {
  42                         this.ContextProvider = contextProvider;
  43                         this.FactBase = factBase;
  44                         this.isUnreachable = isUnreachable;
  45                 }
  46
  47                 #region Implementation of IFactBase<Variable>
  48                 public ProofOutcome IsNull (APC pc, Variable variable)
  49                 {
  50                         return this.FactBase.IsNull (pc, variable);
  51                 }
  52
  53                 public ProofOutcome IsNonNull (APC pc, Variable variable)
  54                 {
  55                         return this.FactBase.IsNonNull (pc, variable);
  56                 }
  57
  58                 public bool IsUnreachable (APC pc)
  59                 {
  60                         if (this.isUnreachable != null && this.isUnreachable (pc))
  61                                 return true;
  62
  63                         return this.FactBase.IsUnreachable (pc);
  64                 }
  65
  66                 protected static bool TryVariable (BoxedExpression e, out Variable v)
  67                 {
  68                         object underlyingVariable = e.UnderlyingVariable;
  69                         if (underlyingVariable is Variable) {
  70                                 v = (Variable) underlyingVariable;
  71                                 return true;
  72                         }
  73
  74                         v = default(Variable);
  75                         return false;
  76                 }
  77                 #endregion
  78
  79                 #region Implementation of IFactQuery<BoxedExpression,Variable>
  80                 public virtual ProofOutcome IsNull (APC pc, BoxedExpression expr)
  81                 {
  82                         Variable v;
  83                         if (TryVariable (expr, out v)) {
  84                                 ProofOutcome outcome = this.FactBase.IsNull (pc, v);
  85                                 if (outcome != ProofOutcome.Top)
  86                                         return outcome;
  87                         }
  88                         return ProofOutcome.Top;
  89                 }
  90
  91                 public virtual ProofOutcome IsNonNull (APC pc, BoxedExpression expr)
  92                 {
  93                         Variable v;
  94                         if (TryVariable (expr, out v)) {
  95                                 ProofOutcome outcome = this.FactBase.IsNonNull (pc, v);
  96                                 if (outcome != ProofOutcome.Top)
  97                                         return outcome;
  98                         }
  99                         return ProofOutcome.Top;
 100                 }
 101
 102                 public ProofOutcome IsTrue (APC pc, BoxedExpression expr)
 103                 {
 104                         return IsNonZero (pc, expr);
 105                 }
 106
 107                 public ProofOutcome IsTrueImply (APC pc, LispList<BoxedExpression> positiveAssumptions, LispList<BoxedExpression> negativeAssumptions, BoxedExpression goal)
 108                 {
 109                         ProofOutcome outcome = IsTrue (pc, goal);
 110                         switch (outcome) {
 111                         case ProofOutcome.True:
 112                         case ProofOutcome.Bottom:
 113                                 return outcome;
 114                         default:
 115                                 return ProofOutcome.Top;
 116                         }
 117                 }
 118
 119                 public ProofOutcome IsGreaterEqualToZero (APC pc, BoxedExpression expr)
 120                 {
 121                         return ProofOutcome.Top;
 122                 }
 123
 124                 public ProofOutcome IsLessThan (APC pc, BoxedExpression expr, BoxedExpression right)
 125                 {
 126                         return ProofOutcome.Top;
 127                 }
 128
 129                 public ProofOutcome IsNonZero (APC pc, BoxedExpression expr)
 130                 {
 131                         return IsNonNull (pc, expr);
 132                 }
 133                 #endregion
 134         }
 135 }