0

I would like to define my own rules for what a section of a document is, then use this so I can popup a list of sections I can auto-complete or use arrow keys to jump between them.

Take a simple example where sections match against ^SECTION\s(.*), how would this be possible?

eg:

Some Text

SECTION Section One

Some More text

SECTION Section Two

Other text.

How could I make a menu that pops up all sections, and activating the item navigates the cursor to the selected section?


Note that I'm not sure if this question is spesific to ivy.

3

This is exactly what Imenu is for.

You can define positions to jump to using a menu. The menu can be in the menu-bar or popup, or you can use completion against it as a popup (e.g. in buffer *Completions*).

See the Emacs Wiki page linked above - it introduces multiple ways of using Imenu.

Imenu+, for instance, offers a few improvements for Imenu, such as better sorting of submenus and menu items, and toggling sorting and case-sensitivity.

For Elisp information about it see also the Elisp manual, node Imenu and its subnodes.

The general idea is that you set buffer-local variable imenu-generic-expression in a given buffer, to organize sections there to access by menu. The variable value is a list of elements (MENU-TITLE REGEXP INDEX), where REGEXP recognizes (defines) a section.


If you use Icicles then you can use completion (so different keys) to navigate among or search Imenu items - see Icicles Imenu.

  • Does Imenu allow me to do this in a way that can be assigned to a key? - so one function can initialize one list, another function a different kind of imenu? - I ask this because the docs read to me as if defining the imenu regex will prevent regular imenu from being used. – ideasman42 Feb 10 '18 at 23:56
  • Sorry, I don't understand your followup question in the comment. What list(s)? What "regular imenu"? Perhaps your original question is not clear/complete? – Drew Feb 10 '18 at 23:59
  • Say I want one key to jump between functions, another key to jump between sections of documentation (doxygen groups for eg). Can Imenu be setup so both are possible? – ideasman42 Feb 11 '18 at 0:00
  • That's a different question. Vanilla Imenu is an Emacs menu - usable with the mouse. There are other, related Imenu features linked to from that wiki page, however, some of which provide key access. – Drew Feb 11 '18 at 0:03
  • The question is not how to jump between functions/documentation, thats just an example use case. The question is - is it possible to define an imenu - that doesn't become the only kind of imenu for that buffer, so I can assign different key-bindings for different imenus. – ideasman42 Feb 11 '18 at 0:04
0

Here is a working example of a menu that jumps between sections using completing-read (which can be enhanced by enabling ivy):

;; complete init.el (for convenience)

(require 'package)
(package-initialize)
;; optional, you can disable this but `completing-read` is less useful.
(require 'ivy)

;; See: https://emacs.stackexchange.com/a/35033/2418

(defun custom-popup (menu-prompt menu-index menu-content) "
Pop up menu
Takes args: menu-prompt, default-index, menu-content).
Where the content is any number of (string, function) pairs, each representing a menu item.
User can hit just the first char of a menu item to choose it.
Or click it with `mouse-1' or `mouse-2' to select it.
Or hit RET immediately to select the default item.
"
  (interactive)
  (let*
    (
      ;; don't sort when 'completing-read' from 'ivy' is in use.
      (ivy-sort-functions-alist nil)
      (choice
        (completing-read
          ;; menu prompt & content
          menu-prompt menu-content nil t nil nil
          ;; default index
          (nth menu-index menu-content)
          )
        )
      (action  (cdr (assoc choice menu-content)))
      )
    (funcall action)
    )
  )

;; helper functions

;; https://emacs.stackexchange.com/a/7156/2418 (with minor edits)
(defun matches-in-buffer-forward (regexp regexp-group &optional buffer)
  "return a list of matches and position pairs of REGEXP in BUFFER or the current buffer if not given."
  (let ((matches))
    (save-match-data
      (save-excursion
        (with-current-buffer (or buffer (current-buffer))
          (save-restriction
            (widen)
            (end-of-buffer)
            ;; search backwards since resulting list will be reversed
            (while (search-backward-regexp regexp nil t 1)
              (push (list (match-string-no-properties regexp-group) (match-beginning 0)) matches)
              )
            )
          )
        )
      matches)
    )
  )


(defun doc-jump-section-from-matches (menu-prompt matches &optional buffer) "
Take a list of '(text, positions)' and use them to activate a menu
(with the active item closest above or matching the current line).
"
  (interactive)
  (setq
    menu-content '()
    menu-default-index -1
    index 0)
  (let
    ((point-eol (save-excursion (end-of-line) (point))))
    (dolist
      (section-pair matches)
      (let
        (
          (section-title (nth 0 section-pair))
          (section-pos (nth 1 section-pair))
          )
        (when (>= point-eol section-pos)
          (setq menu-default-index index))
        (add-to-list
          'menu-content
          `
          (
            ,section-title
            .
            (lambda
              ()
              (goto-char ,section-pos)
              ;; move the cursor after the section block
              ;; (forward-paragraph)
              ;; show the section at the top
              (recenter scroll-margin)
              )
            )
          )
        )
      (setq index (+ 1 index))
      )
    (setq menu-content (reverse menu-content))
    (custom-popup menu-prompt menu-default-index menu-content)
    )
  )

;; Jump to 'SECTION' - an example.
(defun my-jump-to-section ()
  (interactive)
  (doc-jump-section-from-matches "Jump: " (matches-in-buffer-forward ".*SECTION\s*\\(.*\\)" 1)))

(global-set-key (kbd "<f8>") 'my-jump-to-section)
  • FWIW: The Lisp code here is not syntactically correct. E.g., missing paren in my-jump-to-matches, missing parameter list and interactive spec in my-jump-to-section. (And doc strings that start and finish in unconventional places - not an error, but odd.) – Drew Jun 1 '18 at 15:01
  • @Drew, thanks - updated the answer to a complete self contained working example. – ideasman42 Jun 2 '18 at 8:12

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