NCalc - Mathematical Expressions Evaluator for .NET

New Post: Call for feedback !

lyme — Sat, 13 Mar 2010 23:23:40 GMT

Sabastienros,

NCALC really does a great job, I've implemented NCALC in a little irc bot I put together, it was extremely quick and easy.

It would be nice if it included a random function eg: random(upperbounds) and random(lower, upper).

Note: NCALC compiles under .net 4.0 without issue.

Thanks.

New Post: How to check the final result type of an expression...

viklele — Wed, 03 Mar 2010 03:43:21 GMT

Thanks Sebastien,

I will try that out.

Regards,

- Vikram

New Post: Own object as Parameter

sebastienros — Tue, 02 Mar 2010 14:03:31 GMT

ANTLR is not compatible with Silverlight. Someone in the forums managed to get it working and I'd like to know how !

New Post: Own object as Parameter

addanki — Tue, 02 Mar 2010 14:01:01 GMT

Hi,

I tried to use the NClc.dll assembly that is present at http://ncalc.codeplex.com . But, it displayed an error message saying that, "It is not possible to add, as it is not built against silverlight runtime....."

Do anyone let me know what might be the reason?

Thank you,

Regards

Ashok

Commented Feature: Own object as Parameter [26352]

Fabske — Sun, 28 Feb 2010 17:15:10 GMT

Hello!

I would like to know if it's possible to give custom object as parametersI means, I've an object type that override the common operators (+,- etc) and I want to know if it's possible to use it as parameters

Sample:

Expression e = new Expression("[x] * [y]");
e.Parameters["x"] = myObjectA;
e.Parameters["y"] = myObjectB;

Console.WriteLine(e.Evaluate());

Thanks for your help !
Comments: ** Comment from web user: Fabske **

You can alos use expression trees. Some usefull links:
http://solutionizing.net/2009/01/20/generic-method-invocation-with-expression-trees/
http://www.codewrecks.com/blog/index.php/2008/10/04/expression-tree-vs-reflection/

Commented Feature: Own object as Parameter [26352]

sebastienros — Sat, 27 Feb 2010 12:50:12 GMT

Cache, and even better, LCG with dynamic method.

Commented Feature: Own object as Parameter [26352]

Fabske — Sat, 27 Feb 2010 11:15:38 GMT

Indeed it's a different way :). And it'll be a lot easier is we don't need to implement an interface.
I just wonder how it'll be about performance. Maybe a cache will be needed to not repeat the same search for types allready analysed.

Commented Feature: Own object as Parameter [26352]

sebastienros — Sat, 27 Feb 2010 10:54:05 GMT

I would maybe go using a different technique: in Number.cs, if the types are unknown, try to get the override for the specific operator through reflexion.

New Post: Own object as Parameter

Fabske — Sat, 27 Feb 2010 10:21:22 GMT

Thanks !

I've added some info to the work item, hope it can help

Commented Feature: Own object as Parameter [26352]

Fabske — Sat, 27 Feb 2010 10:08:54 GMT

The MyCustomObject.cs is a firt implementation of the ICalculable class. As you see, all these cast are very ugly. I wonder if there is a way to use Generics and avoid these, I didn't had the time to try.

Commented Feature: Own object as Parameter [26352]

Fabske — Sat, 27 Feb 2010 10:06:13 GMT

The ICalculable interface

Commented Feature: Own object as Parameter [26352]

Fabske — Sat, 27 Feb 2010 10:05:44 GMT

As I've try a bit here are my 2 cents, maybe it can help you
I didn't find a way to use operators because these cannot be declared in an interface. My goal was to be able to give any object to NCalc if it implement operator overload. But the only way I've found is to use an interface with normal method (see attached ICalculable.cs)
Then I've modified the class number for each operation, for example the Add:

case TypeCode.Object:
ICalculable aCalc = a as ICalculable;
ICalculable bCalc = b as ICalculable;
if (aCalc != null && bCalc != null)
return aCalc.Add(bCalc);
break;

It works but it's not as beautiful as I would like :-)

Closed Issue: NullReference Exception Caught [26301]

sebastienros — Sat, 27 Feb 2010 08:24:53 GMT

I am getting an exception while trying to validate an expression.
Exception is "Object reference not set to an instance of object".

My expression is:
(A>B) + 10 with A=1, B=2

How this error can be removed or is there any better error we can display in this case?

Regards,
Abhishek Shukla
Comments:

An informative message is displayed with the thrown exception

New Post: Ensure result type of expression

sebastienros — Sat, 27 Feb 2010 07:50:08 GMT

I have answered in another post.

New Post: How to check the final result type of an expression...

sebastienros — Sat, 27 Feb 2010 07:49:20 GMT

Well, everything with '&&' or 'and' results in boolean, whereas '&' only results in numeric value. In a more scientific way, you can create a specific Visitor implementation for evaluating each node and returning the intended type. Just like the ExpressionVisitor class.

New Post: Support for Version's

sebastienros — Sat, 27 Feb 2010 07:46:03 GMT

I suppose it's for managing sort of a rule engine, and thus people must have knowledge of what a version number is. So I would suggest you to create a custom function named CompareVersion(v1, v2), which would make this job. This would return -1, 0 or 1 depending on the result.

It's the easiest way to handle it.

Sébastien

New Post: Own object as Parameter

sebastienros — Sat, 27 Feb 2010 07:41:40 GMT

This discussion has been copied to a work item. Click here to go to the work item and continue the discussion.

Created Feature: Own object as Parameter [26352]

sebastienros — Sat, 27 Feb 2010 07:41:38 GMT

New Post: Own object as Parameter

sebastienros — Sat, 27 Feb 2010 07:41:14 GMT

I don't really know if it is possible. I will check. I have a class to handle which operation has to be done between types. I should check there if there is an operator overload for those objects. I had this message as a work item.

Sébastien

New Post: Problem in Expression Evaluation

sebastienros — Sat, 27 Feb 2010 07:39:19 GMT

Hi Abhishek,

Actually this is not the intent of NCalc. Though, we have made another library which can do that. It's http://jint.codeplex.com. It's a Javascript interpreter. It works the same as Ncalc, bbut it is able to execute statements, and thus assign variables among many other things.

Sébastien