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//
// BoxedExpressionExtensions.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.DataStructures;
namespace Mono.CodeContracts.Static.Proving
{
static class BoxedExpressionExtensions
{
public static bool IsConstantIntOrNull(this BoxedExpression e, out int res)
{
res = 0;
if (e.IsConstant) {
IConvertible convertible = e.Constant as IConvertible;
if (convertible != null) {
if (e.Constant is string || e.Constant is float || e.Constant is double)
return false;
try {
res = convertible.ToInt32 (null);
return true;
} catch {
}
}
if (e.Constant == null)
return true;
}
return false;
}
public static bool IsConstantBool(this BoxedExpression e, out bool result)
{
if (e.IsConstant && e.Constant is bool)
return true.With ((bool) e.Constant, out result);
return false.Without (out result);
}
public static bool IsTrivialCondition(this BoxedExpression e, out bool result)
{
int value;
if (e.IsConstantIntOrNull (out value))
return true.With (value != 0, out result);
if (e.IsConstantBool (out result))
return true;
BinaryOperator bop;
BoxedExpression left;
BoxedExpression right;
if (e.IsBinaryExpression (out bop, out left, out right)) {
int l, r;
var isLeftInt = left.IsConstantIntOrNull (out l);
var isRightInt = right.IsConstantIntOrNull (out r);
if (bop == BinaryOperator.Ceq) {
if (isLeftInt && isRightInt)
return true.With (l == r, out result);
bool leftResult;
if (isRightInt && r == 0 && left.IsTrivialCondition (out leftResult))
return true.With (!leftResult, out result);
bool rightResult;
if (isLeftInt && l == 0 && right.IsTrivialCondition (out rightResult))
return true.With (!rightResult, out result);
return false.Without (out result);
}
switch (bop) {
case BinaryOperator.Add:
case BinaryOperator.Add_Ovf:
case BinaryOperator.Add_Ovf_Un:
return true.With (l + r != 0, out result);
case BinaryOperator.And:
return true.With ((l & r) != 0, out result);
case BinaryOperator.Cne_Un:
return true.With (l != r, out result);
case BinaryOperator.Cge:
return true.With (l >= r, out result);
case BinaryOperator.Cge_Un:
return true.With ((uint) l >= (uint) r, out result);
case BinaryOperator.Cgt:
return true.With (l > r, out result);
case BinaryOperator.Cgt_Un:
return true.With ((uint) l > (uint) r, out result);
case BinaryOperator.Cle:
return true.With (l <= r, out result);
case BinaryOperator.Cle_Un:
return true.With ((uint) l <= (uint) r, out result);
case BinaryOperator.Clt:
return true.With (l < r, out result);
case BinaryOperator.Clt_Un:
return true.With ((uint) l < (uint) r, out result);
case BinaryOperator.Div:
if (r == 0)
return false.Without (out result);
return true.With (l / r != 0, out result);
case BinaryOperator.Div_Un:
if (r == 0)
return false.Without (out result);
return true.With ((uint) l / (uint) r != 0, out result);
case BinaryOperator.LogicalAnd:
return true.With (l != 0 && r != 0, out result);
case BinaryOperator.LogicalOr:
return true.With (l != 0 || r != 0, out result);
case BinaryOperator.Mul:
case BinaryOperator.Mul_Ovf:
case BinaryOperator.Mul_Ovf_Un:
return true.With (l * r != 0, out result);
case BinaryOperator.Or:
return true.With ((l | r) != 0, out result);
case BinaryOperator.Rem:
if (r == 0)
return false.Without (out result);
return true.With (l % r != 0, out result);
case BinaryOperator.Rem_Un:
if (r == 0)
return false.Without (out result);
return true.With (((uint) l) % ((uint) r) != 0, out result);
case BinaryOperator.Shl:
return true.With (l << r != 0, out result);
case BinaryOperator.Shr:
return true.With (l >> r != 0, out result);
case BinaryOperator.Shr_Un:
return true.With (((uint) l) >> r != 0, out result);
case BinaryOperator.Sub:
case BinaryOperator.Sub_Ovf:
case BinaryOperator.Sub_Ovf_Un:
return true.With (l - r != 0, out result);
case BinaryOperator.Xor:
return true.With ((l ^ r) != 0, out result);
default:
return false.Without (out result);
}
}
return false.Without (out result);
}
}
}
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