How to Compute logic for Arithmetic Expression in a string variable?

Hello all,

I am performing Arithmetic Operations on my Odata service and When I want to perform these operations dynamically in my Data Provider Class Ext(DPC_EXT), I am unable to do as the Query Operation is returning the Expression into a string variable, so I have to compute this expression dynamically and return  the expected result based on this operation.

For Eg: My string variable consists of  lv_str = ((Price + (( 6 + 6)/5)) > 800))

                              Where price is Field  of my Internal Table.

I have to compute this expression dynamically  and return the records which have price greater than 800...

The lv_str variable changes based on the Query Operation every time...

Can anyone please help me on this...

Thanks in Advance

Harsha