[Emacs-ada-mode] Ada 2005 feature: extended return statement

[Stephen Leake]

deadlyhead <deadlyhead at deadlyhead.com> writes:

> What is the status of Ada 2005 support in ada-mode?  

Somewhat ad-hoc. AdaCore added some stuff, I've added more. But there
has been no attempt to be exhaustive.

> Attempting to type in the return statement triggers an error from ada-mode:
>
>   Missing 'accept' in front of 'do'

Thanks for the example. I've now fixed it in my local code. I'll post
a new version of Ada mode soon.

I have used an extended return statement; apparently I didn't try to
add anything after it. 

> This prevents me from actually entering in a new line after end return;, 
> which can be gotten around, but is annoying.  :-/

Right.

> I'm currently running the version of ada-mode off of the web site, 
> version 3.9.  I understand that you have version 4.0 available via Emacs 
> CVS, and that you're planning to update the site with this version, 
> too.  Does 4.0 have support for extended returns?

It does now :).

> I've gone digging through the source of ada-mode.el a bit, but haven't 
> quite wrapped my head around where all of the decisions for word 
> ordering, indentation, etc, are made, so I'm hesitant to just start 
> hacking, especially without the latest version of the code.  

Yes, it's quite convoluted.

> If you have any suggestions on understanding how this code works,
> though, I'm willing to try adding extended returns to it, though.

I found the problem by using edebug to trace thru the indentation
code, using your example. But I've done this several times before;
it's much more confusing the first time :)


If you are up to applying patches, here's the fix (should work with
3.9):

--- a/emacs_stephe_site_lisp/ada-mode.el
+++ b/emacs_stephe_site_lisp/ada-mode.el
@@ -2872,12 +2872,15 @@
 	  (forward-word 1)
 	  (ada-goto-next-non-ws)
 	  (cond
-	   ((looking-at "\\<\\(loop\\|select\\|if\\|case\\)\\>")
+	   ;;
+	   ;; loop/select/if/case/return
+	   ;;
+	   ((looking-at "\\<\\(loop\\|select\\|if\\|case\\|return\\)\\>")
 	    (save-excursion (ada-check-matching-start (match-string 0)))
 	    (list (save-excursion (back-to-indentation) (point)) 0))
 
 	   ;;
-	   ;; loop/select/if/case/record/select
+	   ;; record
 	   ;;
 	   ((looking-at "\\<record\\>")
 	    (save-excursion
@@ -3930,13 +3933,12 @@
 	      (goto-char (match-beginning 0)))
 
 	     ;;
-	     ;; found 'do' => skip back to 'accept'
+	     ;; found 'do' => skip back to 'accept' or 'return'
 	     ;;
 	     ((looking-at "do")
 	      (unless (ada-search-ignore-string-comment
-		       "accept" t nil nil
-		       'word-search-backward)
-		(error "Missing 'accept' in front of 'do'"))))
+		       "\\<accept\\|return\\>" t)
+		(error "Missing 'accept' or 'return' in front of 'do'"))))
 	    (point))
 
 	(if noerror

-- 
-- Stephe