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;;; haskell-collapse.el --- Collapse expressions -*- lexical-binding: t -*-
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;; Copyright (c) 2014 Chris Done. All rights reserved.
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;; Copyright (c) 2017 Vasantha Ganesh Kanniappan <vasanthaganesh.k@tuta.io>.
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;; This file is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 3, or (at your option)
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;; any later version.
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;; This file is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with this program. If not, see <http://www.gnu.org/licenses/>.
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;;; Code:
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(require 'hideshow)
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;;; TODO:
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;;; -> Make it work for braces
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(defun haskell-hide-toggle ()
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"Toggle visibility of existing forms at point. "
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(interactive)
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(hs-minor-mode 1)
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(save-excursion
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(let* ((modified (buffer-modified-p))
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(inhibit-read-only t)
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(position (haskell-indented-block))
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(beg (car position))
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(end (cdr position)))
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(if (and beg end)
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(if (overlays-in beg end)
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(hs-discard-overlays beg end)
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(hs-make-overlay beg end 'code)))
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(set-buffer-modified-p modified))))
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(defun haskell-blank-line-p ()
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"Returns `t' if line is empty or composed only of whitespace."
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(save-excursion
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(beginning-of-line)
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(= (point-at-eol)
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(progn (skip-chars-forward "[:blank:]") (point)))))
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(defun haskell-indented-block ()
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"return (start-of-indentation . end-of-indentation)"
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(let ((cur-indent (current-indentation))
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(nxt-line-indent (haskell-next-line-indentation 1))
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(prev-line-indent (haskell-next-line-indentation -1))
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(beg-of-line (save-excursion (end-of-line)
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(point))))
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(cond ((and (= cur-indent 0)
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(= nxt-line-indent 0)) nil)
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((haskell-blank-line-p) nil)
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((> nxt-line-indent cur-indent)
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(cons beg-of-line
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(haskell-find-line-with-indentation '> 1)))
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((or (= nxt-line-indent cur-indent)
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(<= prev-line-indent cur-indent))
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(cons (haskell-find-line-with-indentation '>= -1)
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(haskell-find-line-with-indentation '>= 1)))
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(t nil))))
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(defun haskell-next-line-indentation (dir)
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"returns (integer) indentation of the next if dir=1, previous line
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indentation if dir=-1"
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(save-excursion
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(progn
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(while (and (zerop (forward-line dir))
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(haskell-blank-line-p)))
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(current-indentation))))
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(defun haskell-find-line-with-indentation (comparison direction)
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"comparison is >= or >, direction if 1 finds forward, if -1 finds backward"
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(save-excursion
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(let ((start-indent (current-indentation)))
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(progn
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(while (and (zerop (forward-line direction))
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(or (haskell-blank-line-p)
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(funcall comparison (current-indentation) start-indent))))
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(when (= direction 1) (forward-line -1))
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(end-of-line)
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(point)))))
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(defun haskell-hide-toggle-all ()
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"hides all top level functions"
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(interactive)
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(save-excursion
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(goto-char (point-max))
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(while (zerop (forward-line -1))
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(goto-char (point-at-bol))
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(when (= (current-indentation) 0) (haskell-hide-toggle)))))
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(defvar haskell-collapse-mode-map
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(let ((map (make-sparse-keymap)))
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(define-key map (kbd "C-c @ C-c") 'haskell-hide-toggle)
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(define-key map (kbd "C-c @ C-M-c") 'haskell-hide-toggle-all)
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(define-key map (kbd "C-c @ C-M-s") 'haskell-hide-toggle-all)
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(define-key map (kbd "C-c @ C-M-h") 'haskell-hide-toggle-all)
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map)
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"Keymap for using `haskell-collapse-mode'.")
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;;;###autoload
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(define-minor-mode haskell-collapse-mode
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"Minor mode to collapse and expand haskell expressions"
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:init-value nil
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:lighter " Haskell-Collapse"
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:keymap haskell-collapse-mode-map)
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(provide 'haskell-collapse)
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