Re: linq - how to test expression reducers

public static bool ExpressionEquals(this Expression source,Expression
toBeCompared)
{
 if(object.Equals(source,toBeCompared))
  return true;
 else if ((source != null && toBeCompared == null) || (source == null &&
toBeCompared != null))
 {
  return false;
 }
 else if (source.GetType()==toBeCompared.GetType())
 {
   System.Type sourceType = source.GetType();
   var properties = sourceType.GetProperties();
   bool value = true;
   for (int i = 0; i < properties.Length;i++ )
   {
    var info = properties[i];
    var leftValue = info.GetValue(source, null);
    var rightValue = info.GetValue(toBeCompared, null);
    if (leftValue is Expression)
    {
     value &= ExpressionEquals((Expression)leftValue,
(Expression)rightValue);
    }
    else
     value &= object.Equals(leftValue,rightValue);
   }
   return value;
 }
 else
  return false;
}

This seems to work fine for me. Anything that I may missed with that?

On Fri, Aug 15, 2008 at 5:26 PM, Ayende Rahien <[email protected]> wrote:

> That is because the Equal doesn't know how to deal with them, you have to
> write the equality yourself.
>
>
> On Fri, Aug 15, 2008 at 5:20 PM, Chad Lee <[email protected]> wrote:
>
>> I just ran this simple test:
>>
>> var expr1 = Expression.And(
>>   Expression.Constant(true),
>>   Expression.Constant(false));
>>
>> var expr2 = Expression.And(
>>   Expression.Constant(true),
>>   Expression.Constant(false));
>>
>> Assert.Equal(expr1, expr2);
>>
>> which fails....
>>
>> That just seems stupid to me.
>>
>>
>> On Fri, Aug 15, 2008 at 9:08 AM, Ayende Rahien <[email protected]> wrote:
>>
>>> What about something like:
>>> var reducedExpression = Reduce( () => true && x>1 && x<2));
>>> AssertExpressionEq( reducedExpression,
>>>    new BinaryExpression{ And, new (x>1), new (x<2));
>>>
>>>   On Fri, Aug 15, 2008 at 4:54 PM, Tuna Toksöz <[email protected]>wrote:
>>>
>>>>   Hello team,
>>>> I am working on Expression reducers to simplify complex expressions.
>>>> I made LogicalExpressionReducer which simply converts
>>>> not(not(not(true))) to ConstantExpression(false) and (true &
>>>> x.Name=="johndoe") to (x.Name=="john doe"), meaning that it just uses the
>>>> truth table to reduce expressions.
>>>>
>>>> The problem with expressions is that they are trees! For simple ones, it
>>>> is easy to check if I get the same result but complex ones are hard to deal
>>>> with.
>>>> I first thought that I can use .ToString() of expression which produces
>>>> string representation of an expression, that is some thing like
>>>> Assert.AreEqual("false",reducedExpression.ToString())
>>>>
>>>> But this simply sounds incorrect to me. I then thought about using
>>>> visitors to check for equality, but not sure about that.
>>>>
>>>> 2nd one sounds the way to go, but are there any simpler way to test it?
>>>>
>>>> Producing
>>>>
>>>> --
>>>> Tuna Toksöz
>>>>
>>>> Typos included to enhance the readers attention!
>>>>
>>>>
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-- 
Tuna Toksöz

Typos included to enhance the readers attention!

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