Re: Hierarchical query

On Jun 14, 2:47 am, Jan Hidders <hidd..._at_gmail.com> wrote:
> Are you saying that anything for
> which one would typically use XPath can be done just as well with
> regular expressions assuming that the tree is somehow encoded in a
> string?

A set of strings

> This is clearly not the case for the encoding you gave. Or are
> you going to extend that? Perhaps also extend the regular expressions
> a little?

I was going to define tree query in pure language settings, be it regular languges, context free grammars, or else.

> Or did you just have a particular query in mind?

Let's start from scratch again with simpler example. Given a grammar

expr :
  expr '+' expr
| '(' expr ')'
| '1'

and derivation tree find all the '1's that are nested within a pair of brackets. In the example

1 expr

1.1 expr
1.1.1 (
1.1.2 expr
1.1.2.1 expr
1.1.2.1.1 1
1.1.2.2 +
1.1.2.3 expr
1.1.2.3.1 1
1.1.3 )
1.2 +
1.2 expr
1.2.1 1

the query should return nodes 1.1.2.1.1 and 1.1.2.3.1 Received on Thu Jun 14 2007 - 18:41:42 CEST