[emacs-wiki-discuss] Totally small-time dependency tracking

[Sacha Chua]

The only thing this code does is gray out stuff that can't be done
yet. For really cool stuff, we should be doing fancy sorting and
whatnot, but I don't feel up to doing a topological sort in Emacs Lisp
at 2 in the morning. =)

It's easy to change the syntax. For example, we can use 2->1,5 to mean
that this is task 2 and it's dependent on tasks 1 and 5. That might be
fun.

Hope this sparks an aha! moment somewhere. =)

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;;; Task dependency tracking for Planner

;; #A X Do something {{Tasks:1}}
;; #B _ Do another thing {{Depends:1,5}} {{Tasks:2}}
;; #B _ Do yet another thing {{Depends:1}} {{Tasks:3}}

;; Task 3 depends on a completed task, so it will be okay. Task 2
;; still has an incomplete dependency, so it'll be grayed out after
;; (planner-depend-highlight-tasks).

(defface planner-depend-invalid-face
  '((t (:foreground "gray")))
  "Face for tasks with incomplete dependencies."
  :group 'planner-depend)

(defun planner-depend-highlight-tasks ()
  "Gray out all tasks with dependencies not satisfied on the current page."
  (goto-char (point-min))
  (let (found-ids)
    ;; Find all the completed IDs
    (while (re-search-forward "{{Tasks:\\(0-9+\\)}}" nil t)
      (let* ((task-id (number-to-string (match-string 1)))
             (info (planner-current-task-info)))
        (when (string= "X" (planner-task-status info))
          (setq found-ids (cons task-id found-ids)))))
    ;; Highlight everything else
    (goto-char (point-min))
    (while (re-search-forward planner-task-regexp nil t)
      (let ((info (planner-current-task-info))
            dependencies
            failed)
        (when (string-match "{{Depends:\\([0-9,]+\\)}}" 
(planner-task-description info))
          (setq dependencies (split-string (match-string 1 
(planner-task-description info)) ","))
          (while dependencies
            (if (memq (string-to-number (car dependencies)) found-ids)
                (setq dependencies (cdr dependencies))
              (setq dependencies nil
                    failed t)))
          (when failed
            (planner-highlight-region (planner-line-beginning-position)
                                      (planner-line-end-position)
                                      'dependency
                                      100
                                      '(face planner-depend-invalid-face))))))))


-- 
Sacha Chua <address@hidden> - open source geekette
http://sacha.free.net.ph/ - PGP Key ID: 0xE7FDF77C
interests: emacs, gnu/linux, personal information management, juggling
sachac on irc.freenode.net#emacs . YM: sachachua83