#region License
//=============================================================================
// Vici Core - Productivity Library for .NET 3.5
//
// Copyright (c) 2008-2010 Philippe Leybaert
//
// 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.
//=============================================================================
#endregion
using System;
using System.Collections.Generic;
namespace Vici.Core.Parser{
public class IsExpression : Expression
{
private readonly Expression _objectExpression;
private readonly Expression _typeExpression;
public IsExpression(TokenPosition position, Expression objectExpression, Expression typeExpression) : base(position)
{
_objectExpression = objectExpression;
_typeExpression = typeExpression;
}
public override ValueExpression Evaluate(IParserContext context)
{
ClassName className = _typeExpression.Evaluate(context).Value as ClassName;
ValueExpression objectValue = _objectExpression.Evaluate(context);
Type objectType = objectValue.Type;
if (objectValue.Value == null)
return Exp.Value(TokenPosition, false);
objectType = Nullable.GetUnderlyingType(objectType) ?? objectType;
if (className == null)
throw new ExpressionEvaluationException("is operator requires a type. " + _typeExpression + " is not a type", this);
Type checkType = className.Type;
if (!objectType.IsValueType)
return Exp.Value(TokenPosition, checkType.IsAssignableFrom(objectType));
checkType = Nullable.GetUnderlyingType(checkType) ?? checkType;
return Exp.Value(TokenPosition, checkType == objectType);
}
public override string ToString()
{
return "(" + _objectExpression + " is " + _typeExpression + ")";
}
}
}
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