mcs/class/Mono.CodeContracts/Mono.CodeContracts.Static.Analysis.Numerical/IntervalAssumerBase.cs

   1 //
   2 // IntervalAssumerBase.cs
   3 //
   4 // Authors:
   5 //      Alexander Chebaturkin (chebaturkin@gmail.com)
   6 //
   7 // Copyright (C) 2012 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 System.Collections.Generic;
  31
  32 using Mono.CodeContracts.Static.DataStructures;
  33
  34 namespace Mono.CodeContracts.Static.Analysis.Numerical {
  35         abstract class IntervalAssumerBase<TVar, TExpr, TInterval, TNumeric>
  36                 where TInterval : IntervalBase<TInterval, TNumeric>
  37                 where TVar : IEquatable<TVar> {
  38                 public virtual IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> AssumeEqual
  39                         (TExpr left,
  40                          TExpr right,
  41                          IntervalEnvironmentBase
  42                                  <TVar,
  43                                  TExpr,
  44                                  TInterval,
  45                                  TNumeric>
  46                                  env)
  47                 {
  48                         var leftVar = env.Decoder.UnderlyingVariable (left);
  49                         var rightVar = env.Decoder.UnderlyingVariable (right);
  50
  51                         if (env.Contains (leftVar)) {
  52                                 var res = env;
  53                                 var interval = env.Eval (left).Meet (env.Eval (right));
  54
  55                                 res = res.With (leftVar, interval);
  56                                 res = res.With (rightVar, interval);
  57
  58                                 return res;
  59                         }
  60
  61                         if (env.Decoder.IsConstant (left) && env.Decoder.IsConstant (right) &&
  62                             env.Eval (left).Meet (env.Eval (right)).IsBottom)
  63                                 return env.Bottom;
  64
  65                         return env;
  66                 }
  67
  68                 public virtual IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> AssumeEqualToZero
  69                         (TVar var,
  70                          IntervalEnvironmentBase
  71                                  <
  72                                  TVar
  73                                  ,
  74                                  TExpr
  75                                  ,
  76                                  TInterval
  77                                  ,
  78                                  TNumeric
  79                                  >
  80                                  env)
  81                 {
  82                         return env.RefineVariable (var, env.Context.Zero);
  83                 }
  84
  85                 public virtual IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> AssumeNotEqual
  86                         (TExpr left,
  87                          TExpr right,
  88                          IntervalEnvironmentBase
  89                                  <TVar,
  90                                  TExpr,
  91                                  TInterval
  92                                  ,
  93                                  TNumeric
  94                                  > env)
  95                 {
  96                         int value;
  97                         if (env.Decoder.OperatorFor (left).IsRelational () && env.Decoder.IsConstantInt (right, out value))
  98                                 return value == 0 ? env.AssumeTrue (left) : env.AssumeFalse (left);
  99
 100                         var assumer = env.Assumer;
 101                         return assumer.AssumeLessThan (left, right, env).Join (assumer.AssumeLessThan (right, left, env));
 102                 }
 103
 104                 public abstract IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> AssumeLessThan
 105                         (TExpr left,
 106                          TExpr right,
 107                          IntervalEnvironmentBase
 108                                  <TVar,
 109                                  TExpr,
 110                                  TInterval
 111                                  ,
 112                                  TNumeric
 113                                  > env);
 114
 115                 public abstract IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> AssumeLessEqualThan
 116                         (
 117                         TExpr left, TExpr right, IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> env);
 118
 119                 public abstract IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> AssumeNotEqualToZero
 120                         (TVar v, IntervalEnvironmentBase<TVar,TExpr,TInterval,TNumeric> env);
 121
 122                 public abstract IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> AssumeNotEqualToZero
 123                         (TExpr e, IntervalEnvironmentBase<TVar,TExpr,TInterval,TNumeric> env);
 124
 125                 public abstract IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> AssumeLessEqualThan
 126                         (TInterval intv, TVar right, IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> env);
 127
 128                 public abstract IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> AssumeLessThan
 129                         (TInterval intv, TVar right, IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> env);
 130
 131                 public abstract IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> AssumeGreaterEqualThanZero
 132                         (TExpr expr, IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> env);
 133
 134                 protected IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> AssumeConstraints
 135                         (IImmutableMap<TVar, Sequence<TInterval>> constraints,
 136                         IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> env)
 137                 {
 138                         var res = env;
 139                         foreach (var v in constraints.Keys) {
 140                                 var seq = constraints[v];
 141                                 foreach (var intv in seq.AsEnumerable ())
 142                                         res = res.RefineVariable (v, intv);
 143                         }
 144
 145                         return res;
 146                 }
 147
 148                 protected IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> AssumeConstraints
 149                         (
 150                         IDictionary<TVar, Sequence<TInterval>> constraints,
 151                         IntervalEnvironmentBase<TVar, TExpr, TInterval, TNumeric> env)
 152                 {
 153                         var res = env;
 154                         foreach (var v in constraints.Keys) {
 155                                 var seq = constraints[v];
 156                                 foreach (var intv in seq.AsEnumerable ())
 157                                         res = res.RefineVariable (v, intv);
 158                         }
 159
 160                         return res;
 161                 }
 162         }
 163 }