Re: More Regexp help

[Aaron Hill]

Sorry.  I included the wrong version of the code, before I had 
reduced/simplified some of the regular expressions.  See changes below:

On 2020-06-27 10:04 pm, Aaron Hill wrote:
> -----------------------------------------------------
> Broken into individual steps, as you have requested:
>
> ;;;;
> (use-modules (ice-9 regex))
>
> (define string "a bx3 cd -jk -DRx2 rtyu -HJK 31 17x4 -7 -41x3")
> (format #t "\n[1] ~s" string)
>
> (set! string
>   (regexp-substitute/global #f
>     "(^|\\s)(-?)([0-9]+)"
>     string
>     'pre 1 2 "n" 3 'post))
> (format #t "\n[2] ~s" string)

(set! string
  (regexp-substitute/global #f
    "((^|\\s)-?)([0-9]+)"
    string
    'pre 1 "n" 3 'post))


> (set! string
>   (regexp-substitute/global #f
>     "(^|\\s)(\\S+)(x([0-9]+))"
>     string
>     'pre 1 "(* " 2 " " 4 ")" 'post))
> (set! string (string-append "(" string ")"))
> (format #t "\n[3] ~s" string)

(set! string
  (regexp-substitute/global #f
    "(\\S+)x([0-9]+)"
    string
    'pre "(* " 1 " " 2 ")" 'post))


> (define expr (with-input-from-string string read))
> (format #t "\n[4] ~s" expr)
> ;;;;
> ====
> [1] "a bx3 cd -jk -DRx2 rtyu -HJK 31 17x4 -7 -41x3"
> [2] "a bx3 cd -jk -DRx2 rtyu -HJK n31 n17x4 -n7 -n41x3"
> [3] "(a (* b 3) cd -jk (* -DR 2) rtyu -HJK n31 (* n17 4) -n7 (* -n41 
> 3))"
> [4] (a (* b 3) cd -jk (* -DR 2) rtyu -HJK n31 (* n17 4) -n7 (* -n41 3))
> ====


-- Aaron Hill