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;;; haskell-collapse.el --- Collapse expressions -*- lexical-binding: t -*-
;; Copyright (c) 2014 Chris Done. All rights reserved.
;; Copyright (c) 2017 Vasantha Ganesh Kanniappan <vasanthaganesh.k@tuta.io>.
;; This file 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, or (at your option)
;; any later version.
;; This file 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/>.
;;; Code:
(require 'hideshow)
;;; TODO:
;;; -> Make it work for braces
(defun haskell-hide-toggle ()
"Toggle visibility of existing forms at point. "
(interactive)
(hs-minor-mode 1)
(save-excursion
(let* ((modified (buffer-modified-p))
(inhibit-read-only t)
(position (haskell-indented-block))
(beg (car position))
(end (cdr position)))
(if (and beg end)
(if (overlays-in beg end)
(hs-discard-overlays beg end)
(hs-make-overlay beg end 'code)))
(set-buffer-modified-p modified))))
(defun haskell-blank-line-p ()
"Returns `t' if line is empty or composed only of whitespace."
(save-excursion
(beginning-of-line)
(= (point-at-eol)
(progn (skip-chars-forward "[:blank:]") (point)))))
(defun haskell-indented-block ()
"return (start-of-indentation . end-of-indentation)"
(let ((cur-indent (current-indentation))
(nxt-line-indent (haskell-next-line-indentation 1))
(prev-line-indent (haskell-next-line-indentation -1))
(beg-of-line (save-excursion (end-of-line)
(point))))
(cond ((and (= cur-indent 0)
(= nxt-line-indent 0)) nil)
((haskell-blank-line-p) nil)
((> nxt-line-indent cur-indent)
(cons beg-of-line
(haskell-find-line-with-indentation '> 1)))
((or (= nxt-line-indent cur-indent)
(<= prev-line-indent cur-indent))
(cons (haskell-find-line-with-indentation '>= -1)
(haskell-find-line-with-indentation '>= 1)))
(t nil))))
(defun haskell-next-line-indentation (dir)
"returns (integer) indentation of the next if dir=1, previous line
indentation if dir=-1"
(save-excursion
(progn
(while (and (zerop (forward-line dir))
(haskell-blank-line-p)))
(current-indentation))))
(defun haskell-find-line-with-indentation (comparison direction)
"comparison is >= or >, direction if 1 finds forward, if -1 finds backward"
(save-excursion
(let ((start-indent (current-indentation)))
(progn
(while (and (zerop (forward-line direction))
(or (haskell-blank-line-p)
(funcall comparison (current-indentation) start-indent))))
(when (= direction 1) (forward-line -1))
(end-of-line)
(point)))))
(defun haskell-hide-toggle-all ()
"hides all top level functions"
(interactive)
(save-excursion
(goto-char (point-max))
(while (zerop (forward-line -1))
(goto-char (point-at-bol))
(when (= (current-indentation) 0) (haskell-hide-toggle)))))
(defvar haskell-collapse-mode-map
(let ((map (make-sparse-keymap)))
(define-key map (kbd "C-c @ C-c") 'haskell-hide-toggle)
(define-key map (kbd "C-c @ C-M-c") 'haskell-hide-toggle-all)
(define-key map (kbd "C-c @ C-M-s") 'haskell-hide-toggle-all)
(define-key map (kbd "C-c @ C-M-h") 'haskell-hide-toggle-all)
map)
"Keymap for using `haskell-collapse-mode'.")
;;;###autoload
(define-minor-mode haskell-collapse-mode
"Minor mode to collapse and expand haskell expressions"
:init-value nil
:lighter " Haskell-Collapse"
:keymap haskell-collapse-mode-map)
(provide 'haskell-collapse)
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