Merge branch 'dev'

6 files changed, 383 insertions, 355 deletions

diff --git a/ext/fg/js/api.js b/ext/fg/js/api.js
deleted file mode 100644
index 643d0360..00000000
--- a/ext/fg/js/api.js
+++ /dev/null
@@ -1,42 +0,0 @@
-/*
- * Copyright (C) 2016  Alex Yatskov <alex@foosoft.net>
- * Author: Alex Yatskov <alex@foosoft.net>
- *
- * 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/>.
- */
-
-
-function bgSendMessage(action, params) {
-    return new Promise((resolve, reject) => chrome.runtime.sendMessage({action, params}, resolve));
-}
-
-function bgFindTerm(text) {
-    return bgSendMessage('findTerm', {text});
-}
-
-function bgFindKanji(text) {
-    return bgSendMessage('findKanji', {text});
-}
-
-function bgRenderText(data, template) {
-    return bgSendMessage('renderText', {data, template});
-}
-
-function bgCanAddDefinitions(definitions, modes) {
-    return bgSendMessage('canAddDefinitions', {definitions, modes});
-}
-
-function bgAddDefinition(definition, mode) {
-    return bgSendMessage('addDefinition', {definition, mode});
-}
diff --git a/ext/fg/js/client.js b/ext/fg/js/client.js
deleted file mode 100644
index 628d5b30..00000000
--- a/ext/fg/js/client.js
+++ /dev/null
@@ -1,289 +0,0 @@
-/*
- * Copyright (C) 2016  Alex Yatskov <alex@foosoft.net>
- * Author: Alex Yatskov <alex@foosoft.net>
- *
- * 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/>.
- */
-
-
-class Client {
-    constructor() {
-        this.popup = new Popup();
-        this.audio = {};
-        this.lastMousePos = null;
-        this.lastTextSource = null;
-        this.activateKey = 16;
-        this.activateBtn = 2;
-        this.enabled = false;
-        this.options = {};
-        this.definitions = null;
-        this.sequence = 0;
-        this.fgRoot = chrome.extension.getURL('fg');
-
-        chrome.runtime.onMessage.addListener(this.onBgMessage.bind(this));
-        window.addEventListener('message', this.onFrameMessage.bind(this));
-        window.addEventListener('mousedown', this.onMouseDown.bind(this));
-        window.addEventListener('mousemove', this.onMouseMove.bind(this));
-        window.addEventListener('keydown', this.onKeyDown.bind(this));
-        window.addEventListener('scroll', (e) => this.hidePopup());
-        window.addEventListener('resize', (e) => this.hidePopup());
-    }
-
-    onKeyDown(e) {
-        if (this.enabled && this.lastMousePos !== null && (e.keyCode === this.activateKey || e.charCode === this.activateKey)) {
-            this.searchAt(this.lastMousePos);
-        }
-    }
-
-    onMouseMove(e) {
-        this.lastMousePos = {x: e.clientX, y: e.clientY};
-        if (this.enabled && (e.shiftKey || e.which === this.activateBtn)) {
-            this.searchAt(this.lastMousePos);
-        }
-    }
-
-    onMouseDown(e) {
-        this.lastMousePos = {x: e.clientX, y: e.clientY};
-        if (this.enabled && (e.shiftKey || e.which === this.activateBtn)) {
-            this.searchAt(this.lastMousePos);
-        } else {
-            this.hidePopup();
-        }
-    }
-
-    onBgMessage({action, params}, sender, callback) {
-        const method = this['api_' + action];
-        if (typeof(method) === 'function') {
-            method.call(this, params);
-        }
-
-        callback();
-    }
-
-    onFrameMessage(e) {
-        const {action, params} = e.data, method = this['api_' + action];
-        if (typeof(method) === 'function') {
-            method.call(this, params);
-        }
-    }
-
-    searchAt(point) {
-        const textSource = Client.textSourceFromPoint(point);
-        if (textSource === null || !textSource.containsPoint(point)) {
-            this.hidePopup();
-            return;
-        }
-
-        if (this.lastTextSource !== null && this.lastTextSource.equals(textSource)) {
-            return;
-        }
-
-        textSource.setEndOffset(this.options.scanLength);
-
-        let defs = [];
-        let seq = -1;
-
-        bgFindTerm(textSource.text())
-            .then(({definitions, length}) => {
-                if (length === 0) {
-                    return Promise.reject();
-                }
-
-                textSource.setEndOffset(length);
-
-                const sentence = Client.extractSentence(textSource, this.options.sentenceExtent);
-                definitions.forEach((definition) => {
-                    definition.url = window.location.href;
-                    definition.sentence = sentence;
-                });
-
-                defs = definitions;
-                seq = ++this.sequence;
-
-                return bgRenderText({definitions, root: this.fgRoot, options: this.options, sequence: seq}, 'term-list.html');
-            })
-            .then((content) => {
-                this.definitions = defs;
-                this.showPopup(textSource, content);
-
-                return bgCanAddDefinitions(defs, ['term_kanji', 'term_kana']);
-            })
-            .then((states) => {
-                if (states !== null) {
-                    states.forEach((state, index) => this.popup.sendMessage('setActionState', {index, state, sequence: seq}));
-                }
-            }, () => this.hidePopup());
-    }
-
-    showPopup(textSource, content) {
-        this.popup.showNextTo(textSource.getRect(), content);
-
-        if (this.options.selectMatchedText) {
-            textSource.select();
-        }
-
-        this.lastTextSource = textSource;
-    }
-
-    hidePopup() {
-        this.popup.hide();
-
-        if (this.options.selectMatchedText && this.lastTextSource !== null) {
-            this.lastTextSource.deselect();
-        }
-
-        this.lastTextSource = null;
-        this.definitions = null;
-    }
-
-    api_setOptions(opts) {
-        this.options = opts;
-    }
-
-    api_setEnabled(enabled) {
-        if (!(this.enabled = enabled)) {
-            this.hidePopup();
-        }
-    }
-
-    api_addNote({index, mode}) {
-        const state = {[mode]: false};
-        bgAddDefinition(this.definitions[index], mode).then((success) => {
-            if (success) {
-                this.popup.sendMessage('setActionState', {index, state, sequence: this.sequence});
-            } else {
-                alert('Note could not be added');
-            }
-        });
-    }
-
-    api_playAudio(index) {
-        const definition = this.definitions[index];
-
-        let url = `https://assets.languagepod101.com/dictionary/japanese/audiomp3.php?kanji=${encodeURIComponent(definition.expression)}`;
-        if (definition.reading) {
-            url += `&kana=${encodeURIComponent(definition.reading)}`;
-        }
-
-        for (const key in this.audio) {
-            this.audio[key].pause();
-        }
-
-        const audio = this.audio[url] || new Audio(url);
-        audio.currentTime = 0;
-        audio.play();
-
-        this.audio[url] = audio;
-    }
-
-    api_displayKanji(kanji) {
-        let defs = [];
-        let seq = -1;
-
-        bgFindKanji(kanji)
-            .then((definitions) => {
-                definitions.forEach((definition) => definition.url = window.location.href);
-
-                defs = definitions;
-                seq = ++this.sequence;
-
-                return bgRenderText({definitions, root: this.fgRoot, options: this.options, sequence: seq}, 'kanji-list.html');
-            })
-            .then((content) => {
-                this.definitions = defs;
-                this.popup.setContent(content, defs);
-
-                return bgCanAddDefinitions(defs, ['kanji']);
-            })
-            .then((states) => {
-                if (states !== null) {
-                    states.forEach((state, index) => this.popup.sendMessage('setActionState', {index, state, sequence: seq}));
-                }
-            });
-    }
-
-    static textSourceFromPoint(point) {
-        const element = document.elementFromPoint(point.x, point.y);
-        if (element !== null) {
-            const names = ['IMG', 'INPUT', 'BUTTON', 'TEXTAREA'];
-            if (names.indexOf(element.nodeName) !== -1) {
-                return new TextSourceElement(element);
-            }
-        }
-
-        const range = document.caretRangeFromPoint(point.x, point.y);
-        if (range !== null) {
-            return new TextSourceRange(range);
-        }
-
-        return null;
-    }
-
-    static extractSentence(source, extent) {
-        const quotesFwd = {'「': '」', '『': '』', "'": "'", '"': '"'};
-        const quotesBwd = {'」': '「', '』': '『', "'": "'", '"': '"'};
-        const terminators = '…。．.？?！!';
-
-        const sourceLocal = source.clone();
-        const position = sourceLocal.setStartOffset(extent);
-        sourceLocal.setEndOffset(position + extent);
-        const content = sourceLocal.text();
-
-        let quoteStack = [];
-
-        let startPos = 0;
-        for (let i = position; i >= startPos; --i) {
-            const c = content[i];
-
-            if (quoteStack.length === 0 && (terminators.indexOf(c) !== -1 || c in quotesFwd)) {
-                startPos = i + 1;
-                break;
-            }
-
-            if (quoteStack.length > 0 && c === quoteStack[0]) {
-                quoteStack.pop();
-            } else if (c in quotesBwd) {
-                quoteStack = [quotesBwd[c]].concat(quoteStack);
-            }
-        }
-
-        quoteStack = [];
-
-        let endPos = content.length;
-        for (let i = position; i < endPos; ++i) {
-            const c = content[i];
-
-            if (quoteStack.length === 0) {
-                if (terminators.indexOf(c) !== -1) {
-                    endPos = i + 1;
-                    break;
-                }
-                else if (c in quotesBwd) {
-                    endPos = i;
-                    break;
-                }
-            }
-
-            if (quoteStack.length > 0 && c === quoteStack[0]) {
-                quoteStack.pop();
-            } else if (c in quotesFwd) {
-                quoteStack = [quotesFwd[c]].concat(quoteStack);
-            }
-        }
-
-        return content.substring(startPos, endPos).trim();
-    }
-}
-
-window.yomiClient = new Client();
diff --git a/ext/fg/js/driver.js b/ext/fg/js/driver.js
new file mode 100644
index 00000000..68cbcdee
--- /dev/null
+++ b/ext/fg/js/driver.js
@@ -0,0 +1,244 @@
+/*
+ * Copyright (C) 2016  Alex Yatskov <alex@foosoft.net>
+ * Author: Alex Yatskov <alex@foosoft.net>
+ *
+ * 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/>.
+ */
+
+
+class Driver {
+    constructor() {
+        this.popup = new Popup();
+        this.audio = {};
+        this.lastMousePos = null;
+        this.lastTextSource = null;
+        this.pendingLookup = false;
+        this.enabled = false;
+        this.options = {};
+        this.definitions = null;
+        this.sequence = 0;
+        this.fgRoot = chrome.extension.getURL('fg');
+
+        chrome.runtime.onMessage.addListener(this.onBgMessage.bind(this));
+        window.addEventListener('message', this.onFrameMessage.bind(this));
+        window.addEventListener('mousedown', this.onMouseDown.bind(this));
+        window.addEventListener('mousemove', this.onMouseMove.bind(this));
+        window.addEventListener('keydown', this.onKeyDown.bind(this));
+        window.addEventListener('scroll', e => this.hidePopup());
+        window.addEventListener('resize', e => this.hidePopup());
+    }
+
+    onKeyDown(e) {
+        if (this.enabled && this.lastMousePos !== null && (e.keyCode === 16 || e.charCode === 16)) {
+            this.searchAt(this.lastMousePos, e.ctrlKey ? 'kanji' : 'terms');
+        } else {
+            this.hidePopup();
+        }
+    }
+
+    onMouseMove(e) {
+        this.lastMousePos = {x: e.clientX, y: e.clientY};
+        if (this.enabled && (e.shiftKey || e.which === 2)) {
+            this.searchAt(this.lastMousePos, e.ctrlKey ? 'kanji' : 'terms');
+        }
+    }
+
+    onMouseDown(e) {
+        this.lastMousePos = {x: e.clientX, y: e.clientY};
+        if (this.enabled && (e.shiftKey || e.which === 2)) {
+            this.searchAt(this.lastMousePos, e.ctrlKey ? 'kanji' : 'terms');
+        } else {
+            this.hidePopup();
+        }
+    }
+
+    onBgMessage({action, params}, sender, callback) {
+        const method = this['api_' + action];
+        if (typeof(method) === 'function') {
+            method.call(this, params);
+        }
+
+        callback();
+    }
+
+    onFrameMessage(e) {
+        const {action, params} = e.data, method = this['api_' + action];
+        if (typeof(method) === 'function') {
+            method.call(this, params);
+        }
+    }
+
+    searchTerms(textSource) {
+        textSource.setEndOffset(this.options.scanLength);
+
+        this.pendingLookup = true;
+        findTerm(textSource.text()).then(({definitions, length}) => {
+            if (definitions.length === 0) {
+                this.pendingLookup = false;
+                this.hidePopup();
+            } else {
+                textSource.setEndOffset(length);
+
+                const sentence = extractSentence(textSource, this.options.sentenceExtent);
+                definitions.forEach(definition => {
+                    definition.url = window.location.href;
+                    definition.sentence = sentence;
+                });
+
+                const sequence = ++this.sequence;
+                return renderText({definitions, sequence, root: this.fgRoot, options: this.options}, 'term-list.html').then(content => {
+                    this.definitions = definitions;
+                    this.pendingLookup = false;
+                    this.showPopup(textSource, content);
+                    return canAddDefinitions(definitions, ['term_kanji', 'term_kana']);
+                }).then(states => {
+                    if (states !== null) {
+                        states.forEach((state, index) => this.popup.invokeApi('setActionState', {index, state, sequence}));
+                    }
+                });
+            }
+        });
+    }
+
+    searchKanji(textSource) {
+        textSource.setEndOffset(1);
+
+        this.pendingLookup = true;
+        findKanji(textSource.text()).then(definitions => {
+            if (definitions.length === 0) {
+                this.pendingLookup = false;
+                this.hidePopup();
+            } else {
+                definitions.forEach(definition => definition.url = window.location.href);
+
+                const sequence = ++this.sequence;
+                return renderText({definitions, sequence, root: this.fgRoot, options: this.options}, 'kanji-list.html').then(content => {
+                    this.definitions = definitions;
+                    this.pendingLookup = false;
+                    this.showPopup(textSource, content);
+                    return canAddDefinitions(definitions, ['kanji']);
+                }).then(states => {
+                    if (states !== null) {
+                        states.forEach((state, index) => this.popup.invokeApi('setActionState', {index, state, sequence}));
+                    }
+                });
+            }
+        });
+    }
+
+    searchAt(point, mode) {
+        if (this.pendingLookup) {
+            return;
+        }
+
+        const textSource = textSourceFromPoint(point);
+        if (textSource === null || !textSource.containsPoint(point)) {
+            this.hidePopup();
+            return;
+        }
+
+        if (this.lastTextSource !== null && this.lastTextSource.equals(textSource)) {
+            return;
+        }
+
+        switch (mode) {
+            case 'terms':
+                this.searchTerms(textSource);
+                break;
+            case 'kanji':
+                this.searchKanji(textSource);
+                break;
+        }
+    }
+
+    showPopup(textSource, content) {
+        this.popup.showNextTo(textSource.getRect(), content);
+
+        if (this.options.selectMatchedText) {
+            textSource.select();
+        }
+
+        this.lastTextSource = textSource;
+    }
+
+    hidePopup() {
+        this.popup.hide();
+
+        if (this.options.selectMatchedText && this.lastTextSource !== null) {
+            this.lastTextSource.deselect();
+        }
+
+        this.lastTextSource = null;
+        this.definitions = null;
+    }
+
+    api_setOptions(opts) {
+        this.options = opts;
+    }
+
+    api_setEnabled(enabled) {
+        if (!(this.enabled = enabled)) {
+            this.hidePopup();
+        }
+    }
+
+    api_addNote({index, mode}) {
+        const state = {[mode]: false};
+        addDefinition(this.definitions[index], mode).then(success => {
+            if (success) {
+                this.popup.invokeApi('setActionState', {index, state, sequence: this.sequence});
+            } else {
+                alert('Note could not be added');
+            }
+        });
+    }
+
+    api_playAudio(index) {
+        const definition = this.definitions[index];
+
+        let url = `https://assets.languagepod101.com/dictionary/japanese/audiomp3.php?kanji=${encodeURIComponent(definition.expression)}`;
+        if (definition.reading) {
+            url += `&kana=${encodeURIComponent(definition.reading)}`;
+        }
+
+        for (const key in this.audio) {
+            this.audio[key].pause();
+        }
+
+        const audio = this.audio[url] || new Audio(url);
+        audio.currentTime = 0;
+        audio.play();
+
+        this.audio[url] = audio;
+    }
+
+    api_displayKanji(kanji) {
+        findKanji(kanji).then(definitions => {
+            definitions.forEach(definition => definition.url = window.location.href);
+
+            const sequence = ++this.sequence;
+            return renderText({definitions, sequence, root: this.fgRoot, options: this.options}, 'kanji-list.html').then(content => {
+                this.definitions = definitions;
+                this.popup.setContent(content, definitions);
+                return canAddDefinitions(definitions, ['kanji']);
+            }).then(states => {
+                if (states !== null) {
+                    states.forEach((state, index) => this.popup.invokeApi('setActionState', {index, state, sequence}));
+                }
+            });
+        });
+    }
+}
+
+window.driver = new Driver();
diff --git a/ext/fg/js/frame.js b/ext/fg/js/frame.js
index 8f3d3877..8a99a405 100644
--- a/ext/fg/js/frame.js
+++ b/ext/fg/js/frame.js
@@ -17,48 +17,39 @@
  */
 
 
+function invokeApi(action, params, target) {
+    target.postMessage({action, params}, '*');
+}
+
 function registerKanjiLinks() {
     for (const link of Array.from(document.getElementsByClassName('kanji-link'))) {
-        link.addEventListener('click', (e) => {
+        link.addEventListener('click', e => {
             e.preventDefault();
-            window.parent.postMessage({action: 'displayKanji', params: e.target.innerHTML}, '*');
+            invokeApi('displayKanji', e.target.innerHTML, window.parent);
         });
     }
 }
 
 function registerAddNoteLinks() {
     for (const link of Array.from(document.getElementsByClassName('action-add-note'))) {
-        link.addEventListener('click', (e) => {
+        link.addEventListener('click', e => {
             e.preventDefault();
             const ds = e.currentTarget.dataset;
-            window.parent.postMessage({action: 'addNote', params: {index: ds.index, mode: ds.mode}}, '*');
+            invokeApi('addNote', {index: ds.index, mode: ds.mode}, window.parent);
         });
     }
 }
 
 function registerAudioLinks() {
     for (const link of Array.from(document.getElementsByClassName('action-play-audio'))) {
-        link.addEventListener('click', (e) => {
+        link.addEventListener('click', e => {
             e.preventDefault();
             const ds = e.currentTarget.dataset;
-            window.parent.postMessage({action: 'playAudio', params: ds.index}, '*');
+            invokeApi('playAudio', ds.index, window.parent);
         });
     }
 }
 
-function onDomContentLoaded() {
-    registerKanjiLinks();
-    registerAddNoteLinks();
-    registerAudioLinks();
-}
-
-function onMessage(e) {
-    const {action, params} = e.data, method = window['api_' + action];
-    if (typeof(method) === 'function') {
-        method(params);
-    }
-}
-
 function api_setActionState({index, state, sequence}) {
     for (const mode in state) {
         const matches = document.querySelectorAll(`.action-bar[data-sequence="${sequence}"] .action-add-note[data-index="${index}"][data-mode="${mode}"]`);
@@ -75,5 +66,15 @@ function api_setActionState({index, state, sequence}) {
     }
 }
 
-document.addEventListener('DOMContentLoaded', onDomContentLoaded, false);
-window.addEventListener('message', onMessage);
+document.addEventListener('DOMContentLoaded', () => {
+    registerKanjiLinks();
+    registerAddNoteLinks();
+    registerAudioLinks();
+});
+
+window.addEventListener('message', e => {
+    const {action, params} = e.data, method = window['api_' + action];
+    if (typeof(method) === 'function') {
+        method(params);
+    }
+});
diff --git a/ext/fg/js/popup.js b/ext/fg/js/popup.js
index a0eb725c..88b8e4e3 100644
--- a/ext/fg/js/popup.js
+++ b/ext/fg/js/popup.js
@@ -68,7 +68,7 @@ class Popup {
         doc.close();
     }
 
-    sendMessage(action, params, callback) {
+    invokeApi(action, params) {
         if (this.popup !== null) {
             this.popup.contentWindow.postMessage({action, params}, '*');
         }
@@ -81,8 +81,8 @@ class Popup {
 
         this.popup = document.createElement('iframe');
         this.popup.id = 'yomichan-popup';
-        this.popup.addEventListener('mousedown', (e) => e.stopPropagation());
-        this.popup.addEventListener('scroll', (e) => e.stopPropagation());
+        this.popup.addEventListener('mousedown', e => e.stopPropagation());
+        this.popup.addEventListener('scroll', e => e.stopPropagation());
 
         document.body.appendChild(this.popup);
     }
diff --git a/ext/fg/js/util.js b/ext/fg/js/util.js
new file mode 100644
index 00000000..c24ad885
--- /dev/null
+++ b/ext/fg/js/util.js
@@ -0,0 +1,114 @@
+/*
+ * Copyright (C) 2016  Alex Yatskov <alex@foosoft.net>
+ * Author: Alex Yatskov <alex@foosoft.net>
+ *
+ * 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/>.
+ */
+
+
+function invokeApiBg(action, params) {
+    return new Promise((resolve, reject) => chrome.runtime.sendMessage({action, params}, resolve));
+}
+
+function findTerm(text) {
+    return invokeApiBg('findTerm', {text});
+}
+
+function findKanji(text) {
+    return invokeApiBg('findKanji', {text});
+}
+
+function renderText(data, template) {
+    return invokeApiBg('renderText', {data, template});
+}
+
+function canAddDefinitions(definitions, modes) {
+    return invokeApiBg('canAddDefinitions', {definitions, modes});
+}
+
+function addDefinition(definition, mode) {
+    return invokeApiBg('addDefinition', {definition, mode});
+}
+
+function textSourceFromPoint(point) {
+    const element = document.elementFromPoint(point.x, point.y);
+    if (element !== null) {
+        const names = ['IMG', 'INPUT', 'BUTTON', 'TEXTAREA'];
+        if (names.includes(element.nodeName)) {
+            return new TextSourceElement(element);
+        }
+    }
+
+    const range = document.caretRangeFromPoint(point.x, point.y);
+    if (range !== null) {
+        return new TextSourceRange(range);
+    }
+
+    return null;
+}
+
+function extractSentence(source, extent) {
+    const quotesFwd = {'「': '」', '『': '』', "'": "'", '"': '"'};
+    const quotesBwd = {'」': '「', '』': '『', "'": "'", '"': '"'};
+    const terminators = '…。．.？?！!';
+
+    const sourceLocal = source.clone();
+    const position = sourceLocal.setStartOffset(extent);
+    sourceLocal.setEndOffset(position + extent);
+    const content = sourceLocal.text();
+
+    let quoteStack = [];
+
+    let startPos = 0;
+    for (let i = position; i >= startPos; --i) {
+        const c = content[i];
+
+        if (quoteStack.length === 0 && (terminators.includes(c) || c in quotesFwd)) {
+            startPos = i + 1;
+            break;
+        }
+
+        if (quoteStack.length > 0 && c === quoteStack[0]) {
+            quoteStack.pop();
+        } else if (c in quotesBwd) {
+            quoteStack = [quotesBwd[c]].concat(quoteStack);
+        }
+    }
+
+    quoteStack = [];
+
+    let endPos = content.length;
+    for (let i = position; i < endPos; ++i) {
+        const c = content[i];
+
+        if (quoteStack.length === 0) {
+            if (terminators.includes(c)) {
+                endPos = i + 1;
+                break;
+            }
+            else if (c in quotesBwd) {
+                endPos = i;
+                break;
+            }
+        }
+
+        if (quoteStack.length > 0 && c === quoteStack[0]) {
+            quoteStack.pop();
+        } else if (c in quotesFwd) {
+            quoteStack = [quotesFwd[c]].concat(quoteStack);
+        }
+    }
+
+    return content.substring(startPos, endPos).trim();
+}