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66 lines
2.2 KiB
66 lines
2.2 KiB
9 years ago
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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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;; 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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(define-button-type 'haskell-collapse-toggle-button
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'action 'haskell-collapse-toggle-button-callback
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'follow-link t
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'help-echo "Click to expand…")
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(defun haskell-collapse (beg end)
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"Collapse."
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(interactive "r")
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(goto-char end)
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(let ((break nil))
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(while (and (not break)
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(search-backward-regexp "[[({]" beg t 1))
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(unless (elt (syntax-ppss) 3)
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(let ((orig (point)))
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(haskell-collapse-sexp)
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(goto-char orig)
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(forward-char -1)
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(when (= (point) orig)
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(setq break t)))))))
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(defun haskell-collapse-sexp ()
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"Collapse the sexp starting at point."
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(let ((beg (point)))
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(forward-sexp)
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(let ((end (point)))
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(let ((o (make-overlay beg end)))
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(overlay-put o 'invisible t)
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(let ((start (point)))
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(insert "…")
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(let ((button (make-text-button start (point)
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:type 'haskell-collapse-toggle-button)))
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(button-put button 'overlay o)
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(button-put button 'hide-on-click t)))))))
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(defun haskell-collapse-toggle-button-callback (btn)
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"The callback to toggle the overlay visibility."
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(let ((overlay (button-get btn 'overlay)))
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(when overlay
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(overlay-put overlay
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'invisible
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(not (overlay-get overlay
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'invisible)))))
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(button-put btn 'invisible t)
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(delete-region (button-start btn) (button-end btn)))
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(provide 'haskell-collapse)
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