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;;; haskell-move-nested.el --- Change the column of text nested below a line -*- lexical-binding: t -*-
;; Copyright (C) 2010 Chris Done
;; Author: Chris Done <chrisdone@gmail.com>
;; This file is not part of GNU Emacs.
;; 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:
;; This module is intended for Haskell mode users, but is
;; independent of Haskell mode.
;; Example usage:
;; (define-key haskell-mode-map (kbd "C-,") 'haskell-move-nested-left)
;; (define-key haskell-mode-map (kbd "C-.") 'haskell-move-nested-right)
;;; Code:
;;;###autoload
(defun haskell-move-nested (cols)
"Shift the nested off-side-rule block adjacent to point by COLS columns to the right.
In Transient Mark mode, if the mark is active, operate on the contents
of the region instead.
"
(save-excursion
(if (and transient-mark-mode mark-active)
(progn
(indent-rigidly (region-beginning) (region-end) cols)
(setq deactivate-mark nil))
(let ((region (haskell-move-nested-region)))
(when region
(indent-rigidly (car region) (cdr region) cols))))))
;;;###autoload
(defun haskell-move-nested-right (cols)
"Increase indentation of the following off-side-rule block adjacent to point.
Use a numeric prefix argument to indicate amount of indentation to apply.
In Transient Mark mode, if the mark is active, operate on the contents
of the region instead."
(interactive "p")
(haskell-move-nested cols)
)
;;;###autoload
(defun haskell-move-nested-left (cols)
"Decrease indentation of the following off-side-rule block adjacent to point.
Use a numeric prefix argument to indicate amount of indentation to apply.
In Transient Mark mode, if the mark is active, operate on the contents
of the region instead."
(interactive "p")
(haskell-move-nested (- cols))
)
(defun haskell-move-nested-region ()
"Infer region off-side-rule block adjacent to point.
Used by `haskell-move-nested'.
"
(save-excursion
(let ((starting-level (current-column)))
(forward-line)
(let ((current-level (haskell-move-nested-indent-level)))
(let ((start-point (line-beginning-position))
(start-end-point (line-end-position))
(end-point nil)
(last-line 0))
(forward-line)
(while (and (not (= (line-beginning-position) last-line))
(or (> (haskell-move-nested-indent-level) starting-level)
(and (> current-level starting-level)
(>= (haskell-move-nested-indent-level) current-level))))
(setq last-line (line-beginning-position))
(setq end-point (line-end-position))
(forward-line))
(cons start-point (or end-point
start-end-point)))))))
(defun haskell-move-nested-indent-level ()
(max
0
(1- (length
(buffer-substring-no-properties
(line-beginning-position)
(or (save-excursion (goto-char (line-beginning-position))
(search-forward-regexp "[^ ]" (line-end-position) t 1))
(line-beginning-position)))))))
(defun haskell-kill-nested ()
"Kill the nested region after point."
(interactive)
(let ((start (point))
(reg (save-excursion
(search-backward-regexp "^[ ]+" (line-beginning-position) t 1)
(search-forward-regexp "[^ ]" (line-end-position) t 1)
(haskell-move-nested-region))))
(kill-region start (cdr reg))))
(defun haskell-delete-nested ()
"Kill the nested region after point."
(interactive)
(let ((start (point))
(reg (save-excursion
(search-backward-regexp "^[ ]+" (line-beginning-position) t 1)
(search-forward-regexp "[^ ]" (line-end-position) t 1)
(haskell-move-nested-region))))
(delete-region start (cdr reg))))
(provide 'haskell-move-nested)
;;; haskell-move-nested.el ends here
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