Enhance emacs-git-gutter with ivy-mode

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CREATED: <2016-07-14 Thu>

UPDATED: <2016-09-23 Fri>

emacs-git-gutter shows an icon in the gutter area. The icon indicating whether a line has been inserted, modified or deleted in Emacs.

I usually use M-x git-gutter:previous-hunk or M-x git-gutter:next-hunk to navigate between the hunks.

But if there are too many hunks in one file, ivy-mode is more efficient:

(require 'ivy)
(require 'git-gutter)

(defun my-reshape-git-gutter (gutter)
  "Re-shape gutter for `ivy-read'."
  (let* ((linenum-start (aref gutter 3))
         (linenum-end (aref gutter 4))
         (target-line "")
         (target-linenum 1)
         (tmp-line "")
         (max-line-length 0))
    (save-excursion
      (while (<= linenum-start linenum-end)
        (goto-line linenum-start)
        (setq tmp-line (replace-regexp-in-string "^[ \t]*" ""
                                                 (buffer-substring (line-beginning-position)
                                                                   (line-end-position))))
        (when (> (length tmp-line) max-line-length)
          (setq target-linenum linenum-start)
          (setq target-line tmp-line)
          (setq max-line-length (length tmp-line)))

        (setq linenum-start (1+ linenum-start))))
    ;; build (key . linenum-start)
    (cons (format "%s %d: %s"
                  (if (eq 'deleted (aref gutter 1)) "-" "+")
                  target-linenum target-line)
          target-linenum)))

(defun my-goto-git-gutter ()
  (interactive)
  (if git-gutter:diffinfos
      (ivy-read "git-gutters:"
                (mapcar 'my-reshape-git-gutter git-gutter:diffinfos)
                :action (lambda (e)
                          ;; ivy9+ keep `(car e)'
                          ;; ivy8- strip the `(car e)'
                          ;; we handle both data structure
                          (unless (numberp e) (setq e (cdr e)))
                          (goto-line e)))
    (message "NO git-gutters!")))

Screenshot:

git-gutter-and-ivy-nq8.png

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