Date: Fri, 17 Jan 2003 01:40:11 -0800 From: Bakul Shah <bakul@bitblocks.com> To: "Crist J. Clark" <cjc@FreeBSD.ORG> Cc: freebsd-chat@FreeBSD.ORG Subject: Re: Script Challenge Message-ID: <200301170940.EAA14712@dreadnought.cnchost.com> In-Reply-To: Your message of "Thu, 16 Jan 2003 21:44:59 PST." <20030117054458.GA50247@blossom.cjclark.org>
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> 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
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