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//
// AssumeFalseVisitor.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.
//
namespace Mono.CodeContracts.Static.Analysis.Numerical {
abstract class AssumeFalseVisitor<TDomain, TVar, TExpr> :
GenericExpressionVisitor<TDomain, TDomain, TVar, TExpr>
where TDomain : IEnvironmentDomain<TDomain, TVar, TExpr> {
protected AssumeFalseVisitor (IExpressionDecoder<TVar, TExpr> decoder)
: base (decoder)
{
}
public AssumeTrueVisitor<TDomain, TVar, TExpr> TrueVisitor { 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 VisitNot (TExpr expr, TDomain data)
{
return TrueVisitor.Visit (expr, data);
}
public override TDomain VisitEqual (TExpr left, TExpr right, TExpr original, TDomain data)
{
int value;
if (Decoder.TryValueOf (right, ExpressionType.Int32, out value) && value == 0)
// test (left :neq: 0) ==> test (left)
return TrueVisitor.Visit (left, data);
return TrueVisitor.VisitNotEqual (left, right, original, data);
}
public override TDomain VisitLessThan (TExpr left, TExpr right, TExpr original, TDomain data)
{
// !(left < right) ==> right <= left
return TrueVisitor.VisitLessEqualThan (right, left, original, data);
}
public override TDomain VisitLessEqualThan (TExpr left, TExpr right, TExpr original, TDomain data)
{
// !(left <= right) ==> right < left
return TrueVisitor.VisitLessThan (right, left, original, data);
}
}
}
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