Re: help to get this running faster

[David Pirotte <david at altosw dot be>]

Mikael Djurfeldt wrote:
> ...
> 1. The support for optional arguments is currently slow.  Don't use
>    this in inner loops.
> 
> 2. Guile's implementation of continuations is heavy.  Again, avoid
>    this in inner loops.
> 
> 3. `read-line' is currently an interpreted Scheme closure.  We should
>    optimize this, but haven't got to it yet.  If you can use the
>    low-level %read-line as a temporary kludge, this will speed up your
>    code.

Many thanaks to all suggestions, here is what I did:

can someone give me a little example on how I could get precise figures on
execution time, cons ...

thanks,
david


;; -- module (alto tabreader)

(define-module (alto tabreader))

(export char-pos
	get-tokens
	load-records)

;; (use-modules (ice-9 optargs))
;; (use-modules (ice-9 format))


(define (char-pos char str start end)
  ;; (format #t "Char:	~A~%Str:	~A~%Start:	~A~%End:	~A~%"
  ;; char str start end)
  (catch 'exit
	 (lambda ()
	   (do ((i start (+ i 1)))
	       ((>= i end) #f)
	     (if (char=? (string-ref str i) char)
		 (throw 'exit i))))
	 (lambda (key index)
	   index)))

;; (char-pos #\tab "david	pirotte")

(define (get-tokens str sep)
  (let ((tokens '())
	(start 0)
	(str-len (string-length str)))
    (do ((end (char-pos sep str start str-len)))
	((not end)
	 (reverse! (cons (substring str start str-len) tokens)))
      (set! tokens (cons (substring str start end) tokens))
      (set! start (+ 1 end))
      (set! end (char-pos sep str start str-len)))))

;; (get-tokens "david	pirotte	musician")

(define (load-records fname field-sep)
  (call-with-input-file fname
    (lambda (i-stream)
      (do ((records '())
	   (line (%read-line i-stream) (%read-line i-stream)))
	  ((eof-object? (car line)) (reverse! records))
	(set! records (cons (get-tokens (car line) field-sep)
			    records))))))

;; (load-records "/usr/alto/projects/postgres/essai-122.tab" #\tab)
;; (load-records "/usr/alto/projects/psion/revo/backup/palm-adresses.txt" #\tab)
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