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Re: Efficiency and flexibility of hash-tables
From: |
Joris van der Hoeven |
Subject: |
Re: Efficiency and flexibility of hash-tables |
Date: |
Tue, 11 Feb 2003 12:14:33 +0100 (MET) |
> > So does there exist an adaptive-number-of-slots solution in guile?
>
> No. We'd be happy to include adaptation in the standard Guile
> hash-tables, though. Would it be possible for you to contribute a
> patch?
I don't have much knowledge about how to write low-level guile functions.
In the meantime, you might want to use the following code.
I only use the equal?-based access methods, but it would be easy
to add the eq?- and eqv?-based methods.
The 'adaptive hash tables' are stored as a pair with a usual hashtable and
its number of entries. I have tested the code a bit and it seems to work.
If you find any bugs, then please let me know.
Best wishes, Joris
-----------------------------------------------------------
Joris van der Hoeven <address@hidden>
http://www.texmacs.org: GNU TeXmacs scientific text editor
http://www.math.u-psud.fr/~vdhoeven: personal homepage
-----------------------------------------------------------
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; MODULE : ahash-table.scm (part of GNU TeXmacs)
;; DESCRIPTION : adaptive hash tables
;; COPYRIGHT : (C) 2003 Joris van der Hoeven
;;
;; This software falls under the GNU general public license and comes WITHOUT
;; ANY WARRANTY WHATSOEVER. See the file $TEXMACS_PATH/LICENSE for details.
;; If you don't have this file, write to the Free Software Foundation, Inc.,
;; 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Adaptive hash tables
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(define (make-ahash-table)
(cons (make-hash-table 1) 0))
(define (ahash-ref h key)
(hash-ref (car h) key))
(define (ahash-size h)
(cdr h))
(define (ahash-slots! h new-size)
(let ((new-h (make-hash-table new-size)))
(hash-fold (lambda (key value dummy) (hash-set! new-h key value))
#f (car h))
(set-car! h new-h)))
(define (ahash-set! h key value)
(if (hash-ref (car h) key)
(hash-set! (car h) key value)
(begin
(if (>= (cdr h) (vector-length (car h)))
(ahash-slots! h (+ (* 2 (vector-length (car h))) 1)))
(set-cdr! h (+ (cdr h) 1))
(hash-set! (car h) key value))))
(define (ahash-remove! h key)
(let ((removed (hash-remove! (car h) key)))
(if removed
(begin
(set-cdr! h (- (cdr h) 1))
(if (< (+ (* 4 (cdr h)) 1) (vector-length (car h)))
(ahash-slots! h (quotient (vector-length (car h)) 2)))))
removed))
(define (ahash-fold h)
(hash-fold (car h)))
- Efficiency and flexibility of hash-tables, Joris van der Hoeven, 2003/02/08
- Re: Efficiency and flexibility of hash-tables, Roland Orre, 2003/02/08
- Re: Efficiency and flexibility of hash-tables, Joris van der Hoeven, 2003/02/08
- Re: Efficiency and flexibility of hash-tables, Roland Orre, 2003/02/08
- Re: Efficiency and flexibility of hash-tables, Joris van der Hoeven, 2003/02/08
- Re: Efficiency and flexibility of hash-tables, Mikael Djurfeldt, 2003/02/08
- Re: Efficiency and flexibility of hash-tables,
Joris van der Hoeven <=
- Re: Efficiency and flexibility of hash-tables, Joris van der Hoeven, 2003/02/11
- Re: Efficiency and flexibility of hash-tables, Mikael Djurfeldt, 2003/02/11
- Re: Efficiency and flexibility of hash-tables, Roland Orre, 2003/02/08
- Re: Efficiency and flexibility of hash-tables, Andreas Rottmann, 2003/02/10
- Re: Efficiency and flexibility of hash-tables, Greg Troxel, 2003/02/10
- Re: Efficiency and flexibility of hash-tables, Roland Orre, 2003/02/10
- Re: Efficiency and flexibility of hash-tables, Mikael Djurfeldt, 2003/02/10
- Re: Efficiency and flexibility of hash-tables, Mikael Djurfeldt, 2003/02/10
- Resizing hash tables in Guile, Mikael Djurfeldt, 2003/02/11
- Re: Resizing hash tables in Guile, Roland Orre, 2003/02/11