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kanji-glasses-mode.el

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+;;; kanji-glasses-mode.el --- Minor mode for studying kanji
+
+;; Copyright (C) 2017 Correl Roush
+
+;; Author: Correl Roush <correl@gmail.com>
+;; Version: 0.1
+;; Created: 2017-06-16
+;; Package-Requires: ((kanji-mode "1.0") (memoize "1.0.1"))
+
+;; This file is NOT part of GNU Emacs.
+
+;;; License:
+
+;; 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, 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 GNU Emacs; see the file COPYING.  If not, write to the
+;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+;; Boston, MA 02110-1301, USA.
+
+;;; Commentary:
+
+;; Provides a minor mode for displaying the hiragana reading alongside
+;; kanji present in a buffer. This is accomplished using overlays, so
+;; the contents of the buffer are not modified at all.
+
+;; Enabling this mode will take some time on a buffer with a lot of
+;; kanji present. To combat this, I've memoized the transliteration
+;; method, so it at least won't look up the same thing more than once.
+
+;; Currently relies on kanji-mode for its `km:kanji->hiragana' method
+;; (which in turn relies on having kakasi (http://kakasi.namazu.org/)
+;; installed) to transliterate kanji to hiragana.
+
+;;; Code:
+
+(require 'kanji-mode)
+(require 'memoize)
+
+(defmemoize kanji-glasses-kanji->hiragana (text)
+  "Memoized function to transliterate kanji in TEXT into
+hiragana."
+  (km:kanji->hiragana text))
+
+(defun kanji-glasses-set-overlay-properties ()
+  "Set properties of kanji overlays."
+  (put 'kanji-glasses 'evaporate t)
+  (put 'kanji-glasses 'face '(bold highlight)))
+
+(kanji-glasses-set-overlay-properties)
+
+(defun kanji-glasses-overlay-p (overlay)
+  "Return whether OVERLAY is an overlay of kanji-glasses mode."
+  (eq (overlay-get overlay 'category)
+      'kanji-glasses))
+
+(defun kanji-glasses-wipe (start end)
+  "Clear kanji-glasses overlays between START and END."
+  (dolist (overlay (overlays-in start end))
+    (when (kanji-glasses-overlay-p overlay)
+      (delete-overlay overlay))))
+
+(defun kanji-glasses-adjust (start end)
+  "Apply kanji-glasses to the region defined by START and END."
+
+  (let ((kanji-pattern "\\([\x3400-\x4DB5\x4E00-\x9FCB\xF900-\xFA6A]+\\)")
+        (case-fold-search nil))
+    (save-excursion
+      (save-match-data
+        (goto-char start)
+        (while (re-search-forward kanji-pattern)
+          (let ((overlay (make-overlay (match-beginning 1) (match-end 1))))
+            (overlay-put overlay 'category 'kanji-glasses)
+            (overlay-put overlay 'after-string
+                         (propertize (concat "（" (kanji-glasses-kanji->hiragana (match-string 1)) "）")
+                                     'face '(bold highlight)))))
+        ))))
+
+(defun kanji-glasses-change (start end)
+  "Fontification function to be registered to `jit-lock'.
+Clears and re-applies kanji-glasses overlays to the region
+defined by START and END."
+  (let ((start-line (save-excursion (goto-char start) (line-beginning-position)))
+        (end-line (save-excursion (goto-char end) (line-end-position))))
+    (kanji-glasses-wipe start-line end-line)
+    (kanji-glasses-adjust start-line end-line)))
+
+(define-minor-mode kanji-glasses-mode
+  "Minor mode for studying kanji"
+  :lighter " 勉強"
+  (kanji-glasses-wipe (point-min) (point-max))
+  (if kanji-glasses-mode
+      (progn
+        (jit-lock-register 'kanji-glasses-change))
+    (jit-lock-unregister 'kanji-glasses-change)))
+
+;;; kanji-glasses-mode.el ends here