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//
// SimpleLogicInference.cs
//
// Authors:
// Alexander Chebaturkin (chebaturkin@gmail.com)
//
// Copyright (C) 2011 Alexander Chebaturkin
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using Mono.CodeContracts.Static.AST;
using Mono.CodeContracts.Static.Analysis;
using Mono.CodeContracts.Static.Analysis.Numerical;
using Mono.CodeContracts.Static.ControlFlow;
using Mono.CodeContracts.Static.Lattices;
namespace Mono.CodeContracts.Static.Proving {
class SimpleLogicInference<Expression, Variable> : BasicFacts<Expression, Variable> {
public SimpleLogicInference (IExpressionContextProvider<Expression, Variable> contextProvider, IFactBase<Variable> factBase, Predicate<APC> isUnreachable)
: base (contextProvider, factBase, isUnreachable)
{
}
public override FlatDomain<bool> IsNull(APC pc, BoxedExpression expr)
{
Variable v;
if (TryVariable (expr, out v)) {
FlatDomain<bool> proofOutcome = this.FactBase.IsNull(pc, v);
if (!proofOutcome.IsTop)
return proofOutcome;
}
if (expr.IsConstant) {
object constant = expr.Constant;
if (constant == null)
return ProofOutcome.True;
if (constant is string)
return ProofOutcome.False;
long? longValue = constant.ConvertToLong ();
if (longValue.HasValue)
return longValue == 0 ? ProofOutcome.True : ProofOutcome.False;
return ProofOutcome.Top;
}
BinaryOperator op;
BoxedExpression left;
BoxedExpression right;
if (expr.IsBinaryExpression (out op, out left, out right)) {
if ((op == BinaryOperator.Ceq || op == BinaryOperator.Cobjeq) && IsNull (pc, right).IsTrue ())
return IsNonNull (pc, left);
if (op == BinaryOperator.Cne_Un && IsNull (pc, right).IsTrue ())
return IsNull (pc, left);
}
return ProofOutcome.Top;
}
public override FlatDomain<bool> IsNonNull(APC pc, BoxedExpression expr)
{
Variable v;
if (TryVariable (expr, out v)) {
FlatDomain<bool> proofOutcome = this.FactBase.IsNonNull(pc, v);
if (!proofOutcome.IsTop)
return proofOutcome;
}
if (expr.IsConstant) {
object constant = expr.Constant;
if (constant == null)
return ProofOutcome.False;
if (constant is string)
return ProofOutcome.True;
long? longValue = constant.ConvertToLong();
if (longValue.HasValue)
return longValue != 0 ? ProofOutcome.True : ProofOutcome.False;
return ProofOutcome.Top;
}
BinaryOperator op;
BoxedExpression left;
BoxedExpression right;
if (expr.IsBinaryExpression (out op, out left, out right)) {
if ((op == BinaryOperator.Ceq || op == BinaryOperator.Cobjeq) && IsNull (pc, right).IsTrue ())
return IsNull (pc, left);
if (op == BinaryOperator.Cne_Un && IsNull (pc, right).IsTrue ())
return IsNonNull (pc, left);
}
return ProofOutcome.Top;
}
}
}
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