babel question: how to detect the REPL has finished replying

babel question: how to detect the REPL has finished replying

[Alan Schmitt]

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Hello,

I’m tweaking ob-coq and I’m trying to make it more robust. I have
a question about the way the code detects that the toplevel has finished
replying. Here is the current code (the function name has changed, but
the code is the same):

#+begin_src emacs-lisp
(defun org-babel-coq-run-one-phrase (phrase session)
  (let ((pt (lambda ()
	      (marker-position
	       (process-mark (get-buffer-process (current-buffer)))))))
    (org-babel-coq-clean-prompt
     (org-babel-comint-in-buffer session
       (let ((start (funcall pt)))
	 (with-temp-buffer
	   (insert phrase)
	   (comint-send-region (coq-proc) (point-min) (point-max))
	   (comint-send-string (coq-proc)
	    (if (string= (buffer-substring (- (point-max) 1) (point-max)) ".")
		"\n"
	      ".\n")))
	 (while (equal start (funcall pt)) (sleep-for 0.1))
	 (buffer-substring start (funcall pt)))))))
#+end_src

If I read this correctly, this code waits until the REPL has sent
something, and then it returns it. Unfortunately, Coq’s replies may be
on several lines, and I have seen some of the output not being captured
sometimes.

I’m wondering if it is possible to make this more robust, for instance
by detecting the prompt.

Here is an example of an interaction with the toplevel (the square
denotes the position of the cursor after the interaction):
#+begin_example
Coq < Check S.
S
     : nat -> nat

Coq < ■
#+end example

Could one try to match "Coq < $" on the buffer-substring, and only
return when it matches?

Thanks,

Alan

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Re: babel question: how to detect the REPL has finished replying

[Aaron Ecay]

Hi Alan,

Other backends send an unlikely string literal to the interpreter as the
last command, which will be echoed back verbatim.  The code detects the
presence of this string in the output stream, and thus knows that the
interaction has finished.  Check out the ‘org-babel-comint-with-output’
macro for the implementation.

(This is the usual function of the org-babel-coq-eoe variable that your
last patch deleted.  It was probably cargo-culted in from another
backend and never properly implemented.)

Hope this is helpful,

-- 
Aaron Ecay

Re: babel question: how to detect the REPL has finished replying

[Alan Schmitt]

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Hello Aaron,

On 2016-02-11 20:57, Aaron Ecay <aaronecay@gmail.com> writes:

> Hi Alan,
>
> Other backends send an unlikely string literal to the interpreter as the
> last command, which will be echoed back verbatim.  The code detects the
> presence of this string in the output stream, and thus knows that the
> interaction has finished.  Check out the ‘org-babel-comint-with-output’
> macro for the implementation.
>
> (This is the usual function of the org-babel-coq-eoe variable that your
> last patch deleted.  It was probably cargo-culted in from another
> backend and never properly implemented.)
>
> Hope this is helpful,

It is, thank you for the suggestion. I’m going to look into how it’s
used in other languages.

Alan

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