Slurp

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+;;; org-link-edit.el --- Slurp and barf with Org links
+
+;; Copyright (C) 2015 Kyle Meyer <kyle@kyleam.com>
+
+;; Author:  Kyle Meyer <kyle@kyleam.com>
+;; URL: https://github.com/kyleam/org-link-edit
+;; Keywords: convenience
+;; Version: 0.1.0
+;; Package-Requires: ((cl-lib "0.5") (org "8.2"))
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; Org Link Edit provides Paredit-inspired slurping and barfing
+;; commands for Org link descriptions.
+;;
+;; There are four commands, all which operate when point is on an Org
+;; link.
+;;
+;; - org-link-edit-forward-slurp-word
+;; - org-link-edit-backward-slurp-word
+;; - org-link-edit-forward-barf-word
+;; - org-link-edit-backward-barf-word
+;;
+;; Org Link Edit doesn't bind these commands to any keys.  Finding
+;; good keys for these commands is difficult because, while it's
+;; convenient to be able to quickly repeat these commands, they won't
+;; be used frequently enough to be worthy of a short, repeat-friendly
+;; binding.  Using Hydra [1] provides a nice solution to this.  After
+;; an initial key sequence, any of the commands will be repeatable
+;; with a single key.  (Plus, you get a nice interface that reminds
+;; you of the keys).  Below is one example of how you could configure
+;; this.
+;;
+;;     (define-key org-mode-map YOUR-KEY
+;;       (defhydra hydra-org-link-edit ()
+;;         "Org Link Edit"
+;;         ("j" org-link-edit-forward-slurp-word "forward slurp")
+;;         ("k" org-link-edit-forward-barf-word "forward barf")
+;;         ("u" org-link-edit-backward-slurp-word "backward slurp")
+;;         ("i" org-link-edit-backward-barf-word "backward barf")
+;;         ("q" nil "cancel")))
+;;
+;; [1] https://github.com/abo-abo/hydra
+
+;;; Code:
+
+(require 'org)
+(require 'org-element)
+(require 'cl-lib)
+
+(defun org-link-edit--get-link-data ()
+  "Return list with information about the link at point.
+The list includes
+- the position at the start of the link
+- the position at the end of the link
+- the link text
+- the link description (nil when on a plain link)"
+  (let ((el (org-element-context)))
+    ;; Don't use `org-element-lineage' because it isn't available
+    ;; until Org version 8.3.
+    (while (and el (not (memq (car el) '(link))))
+      (setq el (org-element-property :parent el)))
+    (unless (eq (car el) 'link)
+      (user-error "Point is not on a link"))
+    (save-excursion
+      (goto-char (org-element-property :begin el))
+      (cond
+       ;; Use match-{beginning,end} because match-end is consistently
+       ;; positioned after ]], while the :end property is positioned
+       ;; at the next word on the line, if one is present.
+       ((looking-at org-bracket-link-regexp)
+        (list (match-beginning 0)
+              (match-end 0)
+              (match-string-no-properties 1)
+              (or (and (match-end 3)
+                       (match-string-no-properties 3))
+                  "")))
+       ((looking-at org-plain-link-re)
+        (list (match-beginning 0)
+              (match-end 0)
+              (match-string-no-properties 0)
+              nil))
+       (t
+        (error "What am I looking at?"))))))
+
+;;;###autoload
+(defun org-link-edit-forward-slurp-word (&optional n)
+  "Slurp N trailing words into link's description.
+
+  The \[\[http://orgmode.org/\]\[Org mode\]\] site
+
+                        |
+                        v
+
+  The \[\[http://orgmode.org/\]\[Org mode site\]\]
+
+After slurping, return the slurped text and move point to the
+beginning of the link.
+
+If N is negative, slurp leading words instead of trailing words."
+  (interactive "p")
+  (setq n (or n 1))
+  (cond
+   ((= n 0))
+   ((< n 0)
+    (org-link-edit-backward-slurp-word (- n)))
+   (t
+    (cl-multiple-value-bind (beg end link desc) (org-link-edit--get-link-data)
+      (goto-char (save-excursion
+                   (goto-char end)
+                   (or (forward-word n)
+                       (user-error "Not enough words after the link"))
+                   (point)))
+      (let ((slurped (buffer-substring-no-properties end (point))))
+        (setq slurped (replace-regexp-in-string "\n" " " slurped))
+        (when (and (= (length desc) 0)
+                   (string-match "^\\W*\\(\\w.*\\)" slurped))
+          (setq slurped (match-string 1 slurped)))
+        (setq desc (concat desc slurped)
+              end (+ end (length slurped)))
+        (delete-region beg (point))
+        (insert (org-make-link-string link desc))
+        (goto-char beg)
+        slurped)))))
+
+;;;###autoload
+(defun org-link-edit-backward-slurp-word (&optional n)
+  "Slurp N leading words into link's description.
+
+  The \[\[http://orgmode.org/\]\[Org mode\]\] site
+
+                        |
+                        v
+
+  \[\[http://orgmode.org/\]\[The Org mode\]\] site
+
+After slurping, return the slurped text and move point to the
+beginning of the link.
+
+If N is negative, slurp trailing words instead of leading
+words."
+  (interactive "p")
+  (setq n (or n 1))
+  (cond
+   ((= n 0))
+   ((< n 0)
+    (org-link-edit-forward-slurp-word (- n)))
+   (t
+    (cl-multiple-value-bind (beg end link desc) (org-link-edit--get-link-data)
+      (goto-char (save-excursion
+                   (goto-char beg)
+                   (or (forward-word (- n))
+                       (user-error "Not enough words before the link"))
+                   (point)))
+      (let ((slurped (buffer-substring-no-properties (point) beg)))
+        (when (= (length desc) 0)
+          (setq slurped (progn (string-match "\\(.*\\w\\)\\W*$" slurped)
+                               (match-string 1 slurped))))
+        (setq slurped (replace-regexp-in-string "\n" " " slurped))
+        (setq desc (concat slurped desc)
+              beg (- beg (length slurped)))
+        (delete-region (point) end)
+        (insert (org-make-link-string link desc))
+        (goto-char beg)
+        slurped)))))
+
+(defun org-link-edit--split-first-words (string n)
+  "Split STRING into (N first words . other) cons cell.
+The N first word contains all text up to the next word.  If there
+number of words in STRING is fewer than N, 'other' is nil."
+  (when (< n 0) (user-error "N cannot be negative"))
+  (with-temp-buffer
+    (insert string)
+    (goto-char (point-min))
+    (let ((within-bound (forward-word n)))
+      (skip-syntax-forward "^\w")
+      (cons (buffer-substring 1 (point))
+            (and within-bound
+                 (buffer-substring (point) (point-max)))))))
+
+(defun org-link-edit--split-last-words (string n)
+  "Split STRING into (other . N last words) cons cell.
+The N last words contains all leading text up to the previous
+word.  If there number of words in STRING is fewer than N,
+'other' is nil."
+  (when (< n 0) (user-error "N cannot be negative"))
+  (with-temp-buffer
+    (insert string)
+    (goto-char (point-max))
+    (let ((within-bound (forward-word (- n))))
+      (skip-syntax-backward "^\w")
+      (cons (and within-bound
+                 (buffer-substring 1 (point)))
+            (buffer-substring (point) (point-max))))))
+
+;;;###autoload
+(defun org-link-edit-forward-barf-word (&optional n)
+  "Barf N trailing words from link's description.
+
+  The \[\[http://orgmode.org/\]\[Org mode\]\] site
+
+                        |
+                        v
+
+  The \[\[http://orgmode.org/\]\[Org\]\] mode site
+
+After barfing, return the barfed text and move point to the
+beginning of the link.
+
+If N is negative, barf leading words instead of trailing words."
+  (interactive "p")
+  (setq n (or n 1))
+  (cond
+   ((= n 0))
+   ((< n 0)
+    (org-link-edit-backward-barf-word (- n)))
+   (t
+    (cl-multiple-value-bind (beg end link desc) (org-link-edit--get-link-data)
+      (when (= (length desc) 0)
+        (user-error "Link has no description"))
+      (pcase-let ((`(,new-desc . ,barfed) (org-link-edit--split-last-words
+                                           desc n)))
+        (unless new-desc (user-error "Not enough words in description"))
+        (delete-region beg end)
+        (insert (org-make-link-string link new-desc))
+        (if (string= new-desc "")
+            ;; Two brackets are dropped when pass nil description is
+            ;; passed to `org-make-link-string'.
+            (progn (goto-char (- end (+ 2 (length desc))))
+                   (setq barfed (concat " " barfed)))
+          (goto-char (- end (- (length desc) (length new-desc)))))
+        (insert barfed)
+        (goto-char beg)
+        barfed)))))
+
+;;;###autoload
+(defun org-link-edit-backward-barf-word (&optional n)
+  "Barf N leading words from link's description.
+
+  The \[\[http://orgmode.org/\]\[Org mode\]\] site
+
+                        |
+                        v
+
+  The Org \[\[http://orgmode.org/\]\[mode\]\] site
+
+After barfing, return the barfed text and move point to the
+beginning of the link.
+
+If N is negative, barf trailing words instead of leading words."
+  (interactive "p")
+  (setq n (or n 1))
+  (cond
+   ((= n 0))
+   ((< n 0)
+    (org-link-edit-forward-barf-word (- n)))
+   (t
+    (cl-multiple-value-bind (beg end link desc) (org-link-edit--get-link-data)
+      (when (= (length desc) 0)
+        (user-error "Link has no description"))
+      (pcase-let ((`(,barfed . ,new-desc) (org-link-edit--split-first-words
+                                           desc n)))
+        (unless new-desc (user-error "Not enough words in description"))
+        (delete-region beg end)
+        (insert (org-make-link-string link new-desc))
+        (when (string= new-desc "")
+          (setq barfed (concat barfed " ")))
+        (goto-char beg)
+        (insert barfed)
+        (goto-char (+ beg (length barfed)))
+        barfed)))))
+
+(provide 'org-link-edit)
+;;; org-link-edit.el ends here