yomichan/ext/mixed/js/japanese.js

/*
 * Copyright (C) 2020  Yomichan Authors
 *
 * 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 <https://www.gnu.org/licenses/>.
 */

const jp = (() => {
    const ITERATION_MARK_CODE_POINT = 0x3005;
    const HIRAGANA_SMALL_TSU_CODE_POINT = 0x3063;
    const KATAKANA_SMALL_TSU_CODE_POINT = 0x30c3;
    const KANA_PROLONGED_SOUND_MARK_CODE_POINT = 0x30fc;

    const HIRAGANA_RANGE = [0x3040, 0x309f];
    const KATAKANA_RANGE = [0x30a0, 0x30ff];
    const KANA_RANGES = [HIRAGANA_RANGE, KATAKANA_RANGE];

    const CJK_UNIFIED_IDEOGRAPHS_RANGE = [0x4e00, 0x9fff];
    const CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A_RANGE = [0x3400, 0x4dbf];
    const CJK_UNIFIED_IDEOGRAPHS_EXTENSION_B_RANGE = [0x20000, 0x2a6df];
    const CJK_UNIFIED_IDEOGRAPHS_EXTENSION_C_RANGE = [0x2a700, 0x2b73f];
    const CJK_UNIFIED_IDEOGRAPHS_EXTENSION_D_RANGE = [0x2b740, 0x2b81f];
    const CJK_UNIFIED_IDEOGRAPHS_EXTENSION_E_RANGE = [0x2b820, 0x2ceaf];
    const CJK_UNIFIED_IDEOGRAPHS_EXTENSION_F_RANGE = [0x2ceb0, 0x2ebef];
    const CJK_COMPATIBILITY_IDEOGRAPHS_SUPPLEMENT_RANGE = [0x2f800, 0x2fa1f];
    const CJK_UNIFIED_IDEOGRAPHS_RANGES = [
        CJK_UNIFIED_IDEOGRAPHS_RANGE,
        CJK_UNIFIED_IDEOGRAPHS_EXTENSION_A_RANGE,
        CJK_UNIFIED_IDEOGRAPHS_EXTENSION_B_RANGE,
        CJK_UNIFIED_IDEOGRAPHS_EXTENSION_C_RANGE,
        CJK_UNIFIED_IDEOGRAPHS_EXTENSION_D_RANGE,
        CJK_UNIFIED_IDEOGRAPHS_EXTENSION_E_RANGE,
        CJK_UNIFIED_IDEOGRAPHS_EXTENSION_F_RANGE,
        CJK_COMPATIBILITY_IDEOGRAPHS_SUPPLEMENT_RANGE
    ];

    // Japanese character ranges, roughly ordered in order of expected frequency
    const JAPANESE_RANGES = [
        HIRAGANA_RANGE,
        KATAKANA_RANGE,

        ...CJK_UNIFIED_IDEOGRAPHS_RANGES,

        [0xff66, 0xff9f], // Halfwidth katakana

        [0x30fb, 0x30fc], // Katakana punctuation
        [0xff61, 0xff65], // Kana punctuation
        [0x3000, 0x303f], // CJK punctuation

        [0xff10, 0xff19], // Fullwidth numbers
        [0xff21, 0xff3a], // Fullwidth upper case Latin letters
        [0xff41, 0xff5a], // Fullwidth lower case Latin letters

        [0xff01, 0xff0f], // Fullwidth punctuation 1
        [0xff1a, 0xff1f], // Fullwidth punctuation 2
        [0xff3b, 0xff3f], // Fullwidth punctuation 3
        [0xff5b, 0xff60], // Fullwidth punctuation 4
        [0xffe0, 0xffee]  // Currency markers
    ];

    const SMALL_KANA_SET = new Set(Array.from('ぁぃぅぇぉゃゅょゎァィゥェォャュョヮ'));

    const HALFWIDTH_KATAKANA_MAPPING = new Map([
        ['ｦ', 'ヲヺ-'],
        ['ｧ', 'ァ--'],
        ['ｨ', 'ィ--'],
        ['ｩ', 'ゥ--'],
        ['ｪ', 'ェ--'],
        ['ｫ', 'ォ--'],
        ['ｬ', 'ャ--'],
        ['ｭ', 'ュ--'],
        ['ｮ', 'ョ--'],
        ['ｯ', 'ッ--'],
        ['ｰ', 'ー--'],
        ['ｱ', 'ア--'],
        ['ｲ', 'イ--'],
        ['ｳ', 'ウヴ-'],
        ['ｴ', 'エ--'],
        ['ｵ', 'オ--'],
        ['ｶ', 'カガ-'],
        ['ｷ', 'キギ-'],
        ['ｸ', 'クグ-'],
        ['ｹ', 'ケゲ-'],
        ['ｺ', 'コゴ-'],
        ['ｻ', 'サザ-'],
        ['ｼ', 'シジ-'],
        ['ｽ', 'スズ-'],
        ['ｾ', 'セゼ-'],
        ['ｿ', 'ソゾ-'],
        ['ﾀ', 'タダ-'],
        ['ﾁ', 'チヂ-'],
        ['ﾂ', 'ツヅ-'],
        ['ﾃ', 'テデ-'],
        ['ﾄ', 'トド-'],
        ['ﾅ', 'ナ--'],
        ['ﾆ', 'ニ--'],
        ['ﾇ', 'ヌ--'],
        ['ﾈ', 'ネ--'],
        ['ﾉ', 'ノ--'],
        ['ﾊ', 'ハバパ'],
        ['ﾋ', 'ヒビピ'],
        ['ﾌ', 'フブプ'],
        ['ﾍ', 'ヘベペ'],
        ['ﾎ', 'ホボポ'],
        ['ﾏ', 'マ--'],
        ['ﾐ', 'ミ--'],
        ['ﾑ', 'ム--'],
        ['ﾒ', 'メ--'],
        ['ﾓ', 'モ--'],
        ['ﾔ', 'ヤ--'],
        ['ﾕ', 'ユ--'],
        ['ﾖ', 'ヨ--'],
        ['ﾗ', 'ラ--'],
        ['ﾘ', 'リ--'],
        ['ﾙ', 'ル--'],
        ['ﾚ', 'レ--'],
        ['ﾛ', 'ロ--'],
        ['ﾜ', 'ワ--'],
        ['ﾝ', 'ン--']
    ]);


    function isCodePointInRanges(codePoint, ranges) {
        for (const [min, max] of ranges) {
            if (codePoint >= min && codePoint <= max) {
                return true;
            }
        }
        return false;
    }

    function getWanakana() {
        try {
            if (typeof wanakana !== 'undefined') {
                // eslint-disable-next-line no-undef
                return wanakana;
            }
        } catch (e) {
            // NOP
        }
        return null;
    }


    class JapaneseUtil {
        constructor(wanakana=null) {
            this._wanakana = wanakana;
        }

        // Character code testing functions

        isCodePointKanji(codePoint) {
            return isCodePointInRanges(codePoint, CJK_UNIFIED_IDEOGRAPHS_RANGES);
        }

        isCodePointKana(codePoint) {
            return isCodePointInRanges(codePoint, KANA_RANGES);
        }

        isCodePointJapanese(codePoint) {
            return isCodePointInRanges(codePoint, JAPANESE_RANGES);
        }

        // String testing functions

        isStringEntirelyKana(str) {
            if (str.length === 0) { return false; }
            for (const c of str) {
                if (!isCodePointInRanges(c.codePointAt(0), KANA_RANGES)) {
                    return false;
                }
            }
            return true;
        }

        isStringPartiallyJapanese(str) {
            if (str.length === 0) { return false; }
            for (const c of str) {
                if (isCodePointInRanges(c.codePointAt(0), JAPANESE_RANGES)) {
                    return true;
                }
            }
            return false;
        }

        // Mora functions

        isMoraPitchHigh(moraIndex, pitchAccentPosition) {
            switch (pitchAccentPosition) {
                case 0: return (moraIndex > 0);
                case 1: return (moraIndex < 1);
                default: return (moraIndex > 0 && moraIndex < pitchAccentPosition);
            }
        }

        getKanaMorae(text) {
            const morae = [];
            let i;
            for (const c of text) {
                if (SMALL_KANA_SET.has(c) && (i = morae.length) > 0) {
                    morae[i - 1] += c;
                } else {
                    morae.push(c);
                }
            }
            return morae;
        }

        // Conversion functions

        convertKatakanaToHiragana(text) {
            const wanakana = this._getWanakana();
            let result = '';
            for (const c of text) {
                if (wanakana.isKatakana(c)) {
                    result += wanakana.toHiragana(c);
                } else {
                    result += c;
                }
            }

            return result;
        }

        convertHiraganaToKatakana(text) {
            const wanakana = this._getWanakana();
            let result = '';
            for (const c of text) {
                if (wanakana.isHiragana(c)) {
                    result += wanakana.toKatakana(c);
                } else {
                    result += c;
                }
            }

            return result;
        }

        convertToRomaji(text) {
            const wanakana = this._getWanakana();
            return wanakana.toRomaji(text);
        }

        convertReading(expression, reading, readingMode) {
            switch (readingMode) {
                case 'hiragana':
                    return this.convertKatakanaToHiragana(reading);
                case 'katakana':
                    return this.convertHiraganaToKatakana(reading);
                case 'romaji':
                    if (reading) {
                        return this.convertToRomaji(reading);
                    } else {
                        if (this.isStringEntirelyKana(expression)) {
                            return this.convertToRomaji(expression);
                        }
                    }
                    return reading;
                case 'none':
                    return '';
                default:
                    return reading;
            }
        }

        convertNumericToFullWidth(text) {
            let result = '';
            for (const char of text) {
                let c = char.codePointAt(0);
                if (c >= 0x30 && c <= 0x39) { // ['0', '9']
                    c += 0xff10 - 0x30; // 0xff10 = '0' full width
                    result += String.fromCodePoint(c);
                } else {
                    result += char;
                }
            }
            return result;
        }

        convertHalfWidthKanaToFullWidth(text, sourceMap=null) {
            let result = '';

            // This function is safe to use charCodeAt instead of codePointAt, since all
            // the relevant characters are represented with a single UTF-16 character code.
            for (let i = 0, ii = text.length; i < ii; ++i) {
                const c = text[i];
                const mapping = HALFWIDTH_KATAKANA_MAPPING.get(c);
                if (typeof mapping !== 'string') {
                    result += c;
                    continue;
                }

                let index = 0;
                switch (text.charCodeAt(i + 1)) {
                    case 0xff9e: // dakuten
                        index = 1;
                        break;
                    case 0xff9f: // handakuten
                        index = 2;
                        break;
                }

                let c2 = mapping[index];
                if (index > 0) {
                    if (c2 === '-') { // invalid
                        index = 0;
                        c2 = mapping[0];
                    } else {
                        ++i;
                    }
                }

                if (sourceMap !== null && index > 0) {
                    sourceMap.combine(result.length, 1);
                }
                result += c2;
            }

            return result;
        }

        convertAlphabeticToKana(text, sourceMap=null) {
            let part = '';
            let result = '';

            for (const char of text) {
                // Note: 0x61 is the character code for 'a'
                let c = char.codePointAt(0);
                if (c >= 0x41 && c <= 0x5a) { // ['A', 'Z']
                    c += (0x61 - 0x41);
                } else if (c >= 0x61 && c <= 0x7a) { // ['a', 'z']
                    // NOP; c += (0x61 - 0x61);
                } else if (c >= 0xff21 && c <= 0xff3a) { // ['A', 'Z'] fullwidth
                    c += (0x61 - 0xff21);
                } else if (c >= 0xff41 && c <= 0xff5a) { // ['a', 'z'] fullwidth
                    c += (0x61 - 0xff41);
                } else if (c === 0x2d || c === 0xff0d) { // '-' or fullwidth dash
                    c = 0x2d; // '-'
                } else {
                    if (part.length > 0) {
                        result += this._convertAlphabeticPartToKana(part, sourceMap, result.length);
                        part = '';
                    }
                    result += char;
                    continue;
                }
                part += String.fromCodePoint(c);
            }

            if (part.length > 0) {
                result += this._convertAlphabeticPartToKana(part, sourceMap, result.length);
            }
            return result;
        }

        // Furigana distribution

        distributeFurigana(expression, reading) {
            const fallback = [{furigana: reading, text: expression}];
            if (!reading) {
                return fallback;
            }

            let isAmbiguous = false;
            const segmentize = (reading2, groups) => {
                if (groups.length === 0 || isAmbiguous) {
                    return [];
                }

                const group = groups[0];
                if (group.mode === 'kana') {
                    if (this.convertKatakanaToHiragana(reading2).startsWith(this.convertKatakanaToHiragana(group.text))) {
                        const readingLeft = reading2.substring(group.text.length);
                        const segs = segmentize(readingLeft, groups.splice(1));
                        if (segs) {
                            return [{text: group.text, furigana: ''}].concat(segs);
                        }
                    }
                } else {
                    let foundSegments = null;
                    for (let i = reading2.length; i >= group.text.length; --i) {
                        const readingUsed = reading2.substring(0, i);
                        const readingLeft = reading2.substring(i);
                        const segs = segmentize(readingLeft, groups.slice(1));
                        if (segs) {
                            if (foundSegments !== null) {
                                // more than one way to segmentize the tail, mark as ambiguous
                                isAmbiguous = true;
                                return null;
                            }
                            foundSegments = [{text: group.text, furigana: readingUsed}].concat(segs);
                        }
                        // there is only one way to segmentize the last non-kana group
                        if (groups.length === 1) {
                            break;
                        }
                    }
                    return foundSegments;
                }
            };

            const groups = [];
            let modePrev = null;
            for (const c of expression) {
                const codePoint = c.codePointAt(0);
                const modeCurr = this.isCodePointKanji(codePoint) || codePoint === ITERATION_MARK_CODE_POINT ? 'kanji' : 'kana';
                if (modeCurr === modePrev) {
                    groups[groups.length - 1].text += c;
                } else {
                    groups.push({mode: modeCurr, text: c});
                    modePrev = modeCurr;
                }
            }

            const segments = segmentize(reading, groups);
            if (segments && !isAmbiguous) {
                return segments;
            }
            return fallback;
        }

        distributeFuriganaInflected(expression, reading, source) {
            const output = [];

            let stemLength = 0;
            const shortest = Math.min(source.length, expression.length);
            const sourceHiragana = this.convertKatakanaToHiragana(source);
            const expressionHiragana = this.convertKatakanaToHiragana(expression);
            while (stemLength < shortest && sourceHiragana[stemLength] === expressionHiragana[stemLength]) {
                ++stemLength;
            }
            const offset = source.length - stemLength;

            const stemExpression = source.substring(0, source.length - offset);
            const stemReading = reading.substring(
                0,
                offset === 0 ? reading.length : reading.length - expression.length + stemLength
            );
            for (const segment of this.distributeFurigana(stemExpression, stemReading)) {
                output.push(segment);
            }

            if (stemLength !== source.length) {
                output.push({text: source.substring(stemLength), furigana: ''});
            }

            return output;
        }

        // Miscellaneous

        collapseEmphaticSequences(text, fullCollapse, sourceMap=null) {
            let result = '';
            let collapseCodePoint = -1;
            const hasSourceMap = (sourceMap !== null);
            for (const char of text) {
                const c = char.codePointAt(0);
                if (
                    c === HIRAGANA_SMALL_TSU_CODE_POINT ||
                    c === KATAKANA_SMALL_TSU_CODE_POINT ||
                    c === KANA_PROLONGED_SOUND_MARK_CODE_POINT
                ) {
                    if (collapseCodePoint !== c) {
                        collapseCodePoint = c;
                        if (!fullCollapse) {
                            result += char;
                            continue;
                        }
                    }
                } else {
                    collapseCodePoint = -1;
                    result += char;
                    continue;
                }

                if (hasSourceMap) {
                    sourceMap.combine(Math.max(0, result.length - 1), 1);
                }
            }
            return result;
        }

        // Private

        _getWanakana() {
            const wanakana = this._wanakana;
            if (wanakana === null) { throw new Error('Functions which use WanaKana are not supported in this context'); }
            return wanakana;
        }

        _convertAlphabeticPartToKana(text, sourceMap, sourceMapStart) {
            const wanakana = this._getWanakana();
            const result = wanakana.toHiragana(text);

            // Generate source mapping
            if (sourceMap !== null) {
                let i = 0;
                let resultPos = 0;
                const ii = text.length;
                while (i < ii) {
                    // Find smallest matching substring
                    let iNext = i + 1;
                    let resultPosNext = result.length;
                    while (iNext < ii) {
                        const t = wanakana.toHiragana(text.substring(0, iNext));
                        if (t === result.substring(0, t.length)) {
                            resultPosNext = t.length;
                            break;
                        }
                        ++iNext;
                    }

                    // Merge characters
                    const removals = iNext - i - 1;
                    if (removals > 0) {
                        sourceMap.combine(sourceMapStart, removals);
                    }
                    ++sourceMapStart;

                    // Empty elements
                    const additions = resultPosNext - resultPos - 1;
                    for (let j = 0; j < additions; ++j) {
                        sourceMap.insert(sourceMapStart, 0);
                        ++sourceMapStart;
                    }

                    i = iNext;
                    resultPos = resultPosNext;
                }
            }

            return result;
        }
    }


    return new JapaneseUtil(getWanakana());
})();