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//
// AssumeTrueVisitor.cs
//
// Authors:
// Alexander Chebaturkin (chebaturkin@gmail.com)
//
// Copyright (C) 2012 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 Mono.CodeContracts.Static.DataStructures;
using Mono.CodeContracts.Static.Lattices;
namespace Mono.CodeContracts.Static.Analysis.Numerical {
abstract class AssumeTrueVisitor<TDomain, TVar, TExpr> : GenericExpressionVisitor<TDomain, TDomain, TVar, TExpr>
where TDomain : IEnvironmentDomain<TDomain, TVar, TExpr> {
protected AssumeTrueVisitor (IExpressionDecoder<TVar, TExpr> decoder)
: base (decoder)
{
}
public AssumeFalseVisitor<TDomain, TVar, TExpr> FalseVisitor { get; set; }
protected override TDomain Default (TDomain data)
{
return data;
}
public override TDomain VisitConstant (TExpr left, TDomain data)
{
bool boolValue;
if (Decoder.TryValueOf (left, ExpressionType.Bool, out boolValue))
return boolValue ? data : data.Bottom;
int intValue;
if (Decoder.TryValueOf (left, ExpressionType.Int32, out intValue))
return intValue != 0 ? data : data.Bottom;
return data;
}
public override TDomain VisitLogicalAnd (TExpr left, TExpr right, TExpr original, TDomain data)
{
var leftIsVariable = Decoder.IsVariable (left);
var rightIsVariable = Decoder.IsVariable (right);
var leftIsConstant = Decoder.IsConstant (left);
var rightIsConstant = Decoder.IsConstant (right);
if (leftIsVariable && rightIsConstant || leftIsConstant && rightIsVariable)
return data;
return data.AssumeTrue (left).AssumeTrue (right);
}
public override TDomain VisitLogicalOr (TExpr left, TExpr right, TExpr original, TDomain data)
{
var leftIsVariable = Decoder.IsVariable (left);
var rightIsVariable = Decoder.IsVariable (right);
var leftIsConstant = Decoder.IsConstant (left);
var rightIsConstant = Decoder.IsConstant (right);
if (leftIsVariable && rightIsConstant || leftIsConstant && rightIsVariable)
return data;
var leftBranch = data.AssumeTrue (left);
var rightBranch = data.AssumeTrue (right);
return leftBranch.Join (rightBranch);
}
public override TDomain VisitNot (TExpr expr, TDomain data)
{
return FalseVisitor.Visit (expr, data);
}
protected override bool TryPolarity (TExpr expr, TDomain data, out bool shouldNegate)
{
if (base.TryPolarity (expr, data, out shouldNegate))
return true;
var holds = data.CheckIfHolds (expr);
if (!holds.IsNormal ())
return false.Without (out shouldNegate);
return true.With (!holds.Value, out shouldNegate);
}
}
}
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