Re: Smooth incremental GNU Global gtags behaviour from Emacs

[Kevin Rodgers]

per.nordlow@gmail.com wrote:
> I am using the Emacs interface to the GNU GLOBAL source code tagging
> system and it works mostly great for me. I am however a bit unsatisfied
> with its ruff behaviour when doing incremental updates when a buffer is
> saved into a file from Emacs. In order for it to work properly during
> the development process I want the database to be updated every time I
> save the buffer to a file. I have solved this in the following way:
...
> I have, however, a feeling that this is a bit complicated solution.
> Does anyone have a better idea? If not, I still hope the code can be of
> use to other uses of global from emacs.

I can't critique the overall approach, but I think it could be improved
in minor ways (like using after-save-hook instead of rebinding C-x C-s):

(when (locate-library "gtags")

  (autoload 'gtags-mode "gtags" nil t)

  (when (executable-find "global")

    (defadvice gtags-visit-rootdir (after make-complete-list activate)
      "Rebuilds completion list when changing GLOBAL database rootdir."
      (gtags-make-complete-list))

    (defun gtags-global-dir-p (dir)
      "Return non-nil if directory DIR contains a GLOBAL database."
      (and (file-exists-p (expand-file-name "GPATH" dir))
           (file-exists-p (expand-file-name "GRTAGS" dir))
           (file-exists-p (expand-file-name "GSYMS" dir))
           (file-exists-p (expand-file-name "GTAGS" dir))))

    (defun gtags-global-dir (&optional dir)
      "Return the nearest super directory that contains a GLOBAL database."
      (interactive)
      (when (null dir)
        (setq dir default-directory))
      (cond ((gtags-global-dir-p dir) dir)
            ((equal (file-truename dir) (file-truename "/")) nil)
            (t (gtags-global-dir (file-name-as-directory
                                  (expand-file-name ".." dir))))))

    (defvar gtags-global-complete-list-obsolete-flag nil
      "When non-nil, the GLOBAL complete list should be rebuilt.")

    (defun gtags-global-update ()
      "If current directory is part of a GLOBAL database update it."
      (interactive)
      (when (gtags-global-dir)
        (if (equal (call-process "global" nil nil nil "-vu") 0)
            (setq gtags-global-complete-list-obsolete-flag t)
          (error "global database update failed"))))

    (defun gtags-global-complete-list-maybe ()
      "Rebuild the GLOBAL complete list when indicated.
See `gtags-global-complete-list-obsolete-flag'."
      (interactive)
      (when gtags-global-complete-list-obsolete-flag
        (gtags-make-complete-list)
        (setq gtags-global-complete-list-obsolete-flag nil)))

    (add-hook 'gtags-mode-hook
              (lambda ()
                (add-hook 'after-save-hook 'gtags-global-update nil t)
                (defadvice gtags-find-tag
                  (before gtags-global-complete-list-maybe activate)
                  (gtags-global-complete-list-maybe))
                (defadvice gtags-find-rtag
                  (before gtags-global-complete-list-maybe activate)
                  (gtags-global-complete-list-maybe))
                (defadvice gtags-find-symbol
                  (before gtags-global-complete-list-maybe activate)
                  (gtags-global-complete-list-maybe))
                (defadvice gtags-find-pattern
                  (before gtags-global-complete-list-maybe activate)
                  (gtags-global-complete-list-maybe))
                (defadvice gtags-find-with-grep
                  (before gtags-global-complete-list-maybe activate)
                  (gtags-global-complete-list-maybe))
                (defadvice gtags-find-with-idutils
                  (before gtags-global-complete-list-maybe activate)
                  (gtags-global-complete-list-maybe))
                (defadvice gtags-find-file
                  (before gtags-global-complete-list-maybe activate)
                  (gtags-global-complete-list-maybe))
                (defadvice gtags-parse-file
                  (before gtags-global-complete-list-maybe activate)
                  (gtags-global-complete-list-maybe))
                (defadvice gtags-find-tag-from-here
                  (before gtags-global-complete-list-maybe activate)
                  (gtags-global-complete-list-maybe))
                )                       ; (lambda () ...)
              )                        ; (add-hook 'gtags-mode-hook ...)
    )                            ; (when (executable-find "global") ...)

  ;; Use gtags in all modes for now.
  (gtags-mode 1)
  )                                ; (when (locate-library "gtags") ...)

--
Kevin Rodgers