build a syntax tree

[Arnaud Delobelle]

On Dec 18, 10:43 pm, Federico <federico.bertola.... at gmail.com> wrote:
> Hi I've some trivial question:
>
> for exercise I want to parse a string that like this:
>
> "x -34 + 65 * 96 = 102"
>
> now if I had this ("(25+24)/2") is extremely easy to have a result but
> I want to resolve the above string (for the 'x' variable) what can I
> do?
>
> Especially for symbolic function  I think that I've to build an
> 'operations tree' with a variable table.
> I want to  know how Derive parse this kind of string.
>
> If I've to build a tree, please give me resources and/or examples of
> what physically is a tree and how to build on python.
>
> Thanks :)

You can use a parser generator to build the syntax tree that you want.
See http://wiki.python.org/moin/LanguageParsing for a list.

Perhaps pyparsing is a good one to start with?
http://pyparsing.wikispaces.com/

HTH

--
Arnaud