Re: Fwd: Re: Patch file for colorize module

[Ricardo Wurmus <rekado@elephly.net>]

Hi Sahithi,

do you have any questions about the next steps outlined in the email
below?

Cheers,
Ricardo


Ricardo Wurmus <rekado@elephly.net> writes:

> Hi Sahithi,
>
>>> Have you started on working on this yet?  If so,could you please give us
>>> an update on your progress via email?
>>>
>> I have started out using different functions like
>>
>> |1) regexp-match 2) ||string-contains which resulted same output for
>> strings
>
> The procedures tell you if something matched.
>
>> then i tried 1)
>> string-match 2) string-substitute ended up using string substitute so
>> that the result can be colored one.
>
> “string-match” either returns #f if the expression didn’t match or it
> returns a match structure that tells you *how* the expression was
> matched.  It is especially useful with match groups that are marked with
> parentheses in the regular expression.  See below for an example.
>
>> But I failed executing it. File is
>> attached, Can u suggest where I went wrong.
>
> One obvious failing is in the arguments to “make-soft-port”.  It takes a
> vector of five procedures, but you gave it a vector of one procedure
> followed by an expression beginning with “regexp-substitute/global” and
> then three more procedures.
>
> You need to give it five procedures wrapped in a vector.
>
> How about doing it this way:
>
> --8<---------------cut here---------------start------------->8---
> ;; The port to which we write our potentially colorized strings
> (define target-port (current-output-port))
>
> (define (handle-string str)
>   "Match on the input string STR and return a new string with added
>   color sequences."
>   ;; TODO: match on str and pass the modified string to the output port
>   (display str target-port))
>
> (define my-colorful-port
>   (make-soft-port
>    (vector
>     (lambda (c) (write c target-port))
>     handle-string
>     (lambda () (display "." target-port))
>     (lambda () (char-upcase (read-char)))
>     (lambda () (display "@" target-port)))
>    "rw"))
>
> ;;;; Some tests!
>
> (display "Hello there!" my-colorful-port)  ; no colours
> (display "starting phase “Big gorilla” — watch out!" my-colorful-port)
> (display "phase “Big gorilla” failed" my-colorful-port)
> (display "I heard phase “Big gorilla” failed" my-colorful-port) ; no colours here
> ;;; …and so on…
> --8<---------------cut here---------------end--------------->8---
>
> Now all you need to do is work on the “handle-string” procedure.
>
> I suggest using simpler matching procedures at first.  To get started
> try “string-prefix?” and use it with the string “starting phase”.  This
> won’t work with regular expressions, though.
>
> While you *can* use “regexp-substitute/global”, I don’t think it’s a
> good fit here, because we may want to extend the string matching
> features, which is difficult to do with “regexp-substitute/global”.
> Instead, try to match regular expressions one by one with “string-match”
> and then operate on the match structure it returns.  If it returns #f
> you can move on to the next expression.  If none match you just return
> the original string.  If one matches you *rebuild* the string, but with
> colours applied.
>
> Here’s an example:
>
>   (define str  "My name is Al Jarreau and I’m 76 years old.")
>   (define expr "(My name is )(.*)( and I’m )(.*)( years old.)")
>
> These are five match groups and we want to modify the second and fourth,
> so we can do this:
>
> (or (and=> (string-match expr str)
>            (lambda (m)
>              (string-append
>               (match:substring m 1)
>               (string-upcase (match:substring m 2))
>               (match:substring m 3)
>               (string-reverse (match:substring m 4))
>               (match:substring m 5))))
>     ;; Didn’t match, so return unmodified string.
>     str)
>
> If you don’t understand this example please look up the procedures in
> the Guile manual.
>
>> As per IRC discussion with Ricardo, I tried installing emacs and
>> running a shell.
>
> That is correct.  We were trying to take a look at the features
> guix-build-log-minor-mode provides, but we didn’t get that far.


--
Ricardo