From owner-freebsd-chat  Fri Jan 17  1:40:15 2003
Delivered-To: freebsd-chat@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP
	id 4AE9F37B401; Fri, 17 Jan 2003 01:40:13 -0800 (PST)
Received: from dreadnought.cnchost.com (dreadnought.cnchost.com [207.155.248.18])
	by mx1.FreeBSD.org (Postfix) with ESMTP
	id E80DC43EB2; Fri, 17 Jan 2003 01:40:12 -0800 (PST)
	(envelope-from bakul@bitblocks.com)
Received: from bitblocks.com (adsl-209-204-185-216.sonic.net [209.204.185.216])
	by dreadnought.cnchost.com
	id EAA14712; Fri, 17 Jan 2003 04:40:12 -0500 (EST)
	[ConcentricHost SMTP Relay 1.15]
Message-ID: <200301170940.EAA14712@dreadnought.cnchost.com>
To: "Crist J. Clark" <cjc@FreeBSD.ORG>
Cc: freebsd-chat@FreeBSD.ORG
Subject: Re: Script Challenge 
In-reply-to: Your message of "Thu, 16 Jan 2003 21:44:59 PST."
             <20030117054458.GA50247@blossom.cjclark.org> 
Date: Fri, 17 Jan 2003 01:40:11 -0800
From: Bakul Shah <bakul@bitblocks.com>
Sender: owner-freebsd-chat@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-chat.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-chat>
List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-chat>
X-Loop: FreeBSD.org

> Items in the database can contain sub-items which in turn contain
> sub-items with no hard limit to the recursion.
	...
> I want to sort each level.
	...
> Like I said, I used a Perl script with a recursive function to do
> it, but it ain't all that pretty. I suspect I'm missing a really cool
> way to do it. Any suggestions? (Any language will do.)

Attached below is a small scheme script (using Aubrey
Jaffer's scm and slib -- see /usr/ports/lang/scm).  When it
is fed your sample input

    :b_item (value)
    :a_item (
	    :z_subitem(value)
	    :x_subitem(value)
	    :y_subitem(
		    :r_subsubitem(value)
		    :t_subsubitem(vaule)
		    :s_subsubitem(value)
	    )
	    :w_subitem(value)
    )
    :c_item(value)

It produces

    ((:a_item
       (:w_subitem value)
       (:x_subitem value)
       (:y_subitem
	 (:r_subsubitem value)
	 (:s_subsubitem value)
	 (:t_subsubitem vaule))
       (:z_subitem value))
     (:b_item value)
     (:c_item value))

As you can see the output is formatted as one big list.  Such
"lispy" formats are trivial to read in and easy to process.
But if you don't like that, you can write a simple converter
back to your format or convert this script to linenoise perl.

Note: the input can have any amount of whitespace and there
is virtually no limit on nesting.  But the script does assume
Scheme input syntax.  If not, you have to replace (read) with
your own.  It also assumes all lists have either 1 item or an
even number of items (i.e. no errors).

-- bakul

cat > sortdb.scm <<EOF
#! /usr/local/bin/scm
(require 'sort)
(require 'pretty-print)

(define (less? a b)
  (string<? (symbol->string (car a)) (symbol->string (car b))))

(define (sort-value l)
  (if (or (null? l) (null? (cdr l)))
      l
      (sort-list l '())))

(define (sort-list l result)
  (if (null? l)
      (sort result less?)
      (sort-list (cddr l) (cons (cons (car l) (sort-value (cadr l))) result))))

(define (read-db p)
  (let loop ((result '()) (item (read p)))
       (if (eof-object? item)
	   (sort-value (reverse result))
	   (loop (cons item result) (read p)))))

(pretty-print (read-db (current-input-port)))
EOF
chmod +x sortdb.scm
sortdb.scm < tst-db > sorted-tst-db

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-chat" in the body of the message