bug#61436: Emacs Freezing With Java Files

[Robert Weiner]

Great, will do, thanks, Alan.

-- Bob

> On Apr 17, 2024, at 2:50 PM, Alan Mackenzie <acm@muc.de> wrote:
> 
> Hello again, Bob.
> 
>> On Wed, Apr 17, 2024 at 13:06:50 +0000, Alan Mackenzie wrote:
>>> On Tue, Apr 16, 2024 at 21:35:59 -0400, Robert Weiner wrote:
>>>   Hi Alan:
>>>   I just re-read this whole thread and realized you resolved the problem
>>>   for the Java defun-prompt-regexp but not the C++
>>>   defun-prompt-regexp in Hyperbole's hui-select.el:L404 (probably were
>>>   just tired after all of that).
>>>   Today, someone else reported that the C++ regexp was hanging their
>>>   Emacs.  Do you think you could pick this back up and rework the C++
>>>   regexp as you did the Java one?  It would be a big help; otherwise, I
>>>   think we'll just have to disable that functionality in Hyperbole.
>>>   Best regards,
>>>   Bob
>>>   On Sun, Oct 22, 2023 at 1:18â¯PM Mats Lidell
>>>   <[1]mats.lidell@lidells.se> wrote:
> 
>> Yes, I'll happily finish off that C++ regexp.  I made considerable
>> progress with it back in October, getting smething basically working but
>> with some rough edges.  One problem is that the regexp was ~1600
>> characters long.  I don't know if this might make the program slow -
>> possibly not.
> 
>> I've found the .el file I was working in, and located my notes from
>> October.  It's going to take longer than a day or two, but hopefully
>> less than a week or two.
> 
> It was rather easier than I'd anticipated.  There is my first attempt
> below.  It should find most C++ defun starts, but not all.  In particlar
> it won't recognise one with nested parens or nested template delimiters;
> regexps cannot handle arbitrary nesting,and it didn't seem worth the
> trouble to code in a small bounded degree of nesting, though this surely
> could be done if I'm wrong, here.
> 
> The regexp is not small.  At the latest count it was 2,223 characters
> long.  I hope this won't affect performance too much.
> 
> Please try out this regexp, and let me know how well it's working.
> Thanks!
> 
>> [ .... ]
> 
> 
> 
> (defconst c++-defun-prompt-regexp
>  (let*
>      ((space* "[ \t\n\r\f]*")
>       (space+ "[ \t\n\r\f]+")
>       (ad-hoc-requires-clause
>    (concat "\\(?:requires" space* "[][()<> 
> \t\n\r\f_$a-zA-Z0-9&|\"'+=.,*:~-]+" space* "\\)?"))
>       (id (concat "[_$~a-zA-Z][_$a-zA-Z0-9]*")
>       ;; (concat "\\(\\(~" space* "\\)?" "\\([_$a-zA-Z][_$a-zA-Z0-9]*\\)\\)")
>       )
>       (template-brackets "\\(?:<[^;{}]*>\\)")
>       (id-<> (concat id "\\(?:" space* template-brackets "\\)?"))
>       (id-:: (concat id-<> "\\(?:" space* "::" space* id-<> "\\)*"))
>       (paren-exp "([^{};]*)")
>       (template-exp\? (concat "\\(?:template" space* template-brackets space* 
> "\\)?"))
>       (type-prefix-modifier* (concat "\\(?:\\(?:"
>                      "\\(?:\\<extern" space+ "\"[^\"]+\"\\)"
>                      "\\|"
>                      (regexp-opt '("auto" "const" "explicit" "extern"
>                            "friend" "inline" "mutable"
>                            "noexcept" "overload"
>                            "register" "static" "typedef"
>                            "virtual" "volatile")
>                          'words)
>                      "\\)"
>                      space+
>                      "\\)*"))
>       (type-exp (concat
>          "\\(?:\\(?:" template-brackets space* "\\)?"
>          type-prefix-modifier*
>          "\\(?:\\(?:decltype" space* paren-exp space* "\\)"
>          "\\|"
>          "\\(?:"
>          "\\(?:class\\|enum\\|struct\\|typename\\|union\\)"
>          "\\(?:" space* "\\.\\.\\.\\)?\\)"
>          space+ id space*
>          "\\(?::" id-:: space* "\\)?"
>          "\\|"
>          id-:: space*
>          "\\)"
>          "\\)\\{1,2\\}"))
>       (type-mid-modifier* (concat "\\(?:"
>                   (regexp-opt
>                    '("auto" "consteval" "constexpr"
>                      "constinit" "explicit"
>                      "extern" "friend" "inline"
>                      "mutable" "noexcept" "register"
>                      "static" "template"
>                      "thread_local" "throw"
>                      "virtual" "volatile")
>                    'words)
>                   space+ "\\)*"))
>       (operator-exp (concat "\\(?:operator\\>" space*
>                 "\\(?:[][a-z_+*/%^?&|!~<>,:=-]+"
>                 "\\|()\\|\"\""
>                 "\\)" space*
>                 "\\)"))
> 
>       (name-exp            ; matches foo or (* foo), etc.
>    (concat "\\(?:(" space* "[*&]+" space* id-:: space* "[][()]*" ")"
>        "\\|\\(?:[*&]+" space* "\\)?" id-::
>        "\\)" space*))
>       (type-suffix-modifier* (concat "\\(?:"
>                      (regexp-opt
>                       '("auto" "const" "noexcept"
>                     "requires" "throw" "volatile")
>                       'words)
>                      space+ "\\)*"))
>       (post-paren-modifier* (concat "\\(?:"
>                     (regexp-opt
>                      '("const" "final" "override"
>                    "mutable")
>                      'words)
>                     space* "\\)*")))
> 
>    (concat template-exp\?
>        "\\(?:" ad-hoc-requires-clause "\\)?"
>        type-exp
>        type-mid-modifier*
>        "\\(?:" operator-exp "\\|" name-exp "\\)"
>        type-suffix-modifier*
>        paren-exp space*
>        "\\(?:->" space* type-exp "\\)?"
>        post-paren-modifier*
>        "{"))
> 
> 
> --
> Alan Mackenzie (Nuremberg, Germany).