summaryrefslogtreecommitdiff
path: root/ext/mixed/js/japanese.js
blob: ea1c0065f6f5404b77d03297f971f72eba632103 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
/*
 * 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 jpIsKanji(c) {
    const code = c.charCodeAt(0);
    return code >= 0x4e00 && code < 0x9fb0 || code >= 0x3400 && code < 0x4dc0;
}

function jpIsKana(c) {
    return wanakana.isKana(c);
}

function jpIsJapaneseText(text) {
    for (const c of text) {
        if (jpIsKanji(c) || jpIsKana(c)) {
            return true;
        }
    }
    return false;
}

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

    return result;
}

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

    return result;
}

function jpToRomaji(text) {
    return wanakana.toRomaji(text);
}

function jpConvertReading(expressionFragment, readingFragment, readingMode) {
    switch (readingMode) {
        case 'hiragana':
            return jpKatakanaToHiragana(readingFragment || '');
        case 'katakana':
            return jpHiraganaToKatakana(readingFragment || '');
        case 'romaji':
            if (readingFragment) {
                return jpToRomaji(readingFragment);
            } else {
                if (jpIsKana(expressionFragment)) {
                    return jpToRomaji(expressionFragment);
                }
            }
            return readingFragment;
        default:
            return readingFragment;
    }
}

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

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

        const group = groups[0];
        if (group.mode === 'kana') {
            if (jpKatakanaToHiragana(reading).startsWith(jpKatakanaToHiragana(group.text))) {
                const readingLeft = reading.substring(group.text.length);
                const segs = segmentize(readingLeft, groups.splice(1));
                if (segs) {
                    return [{text: group.text}].concat(segs);
                }
            }
        } else {
            let foundSegments = null;
            for (let i = reading.length; i >= group.text.length; --i) {
                const readingUsed = reading.substring(0, i);
                const readingLeft = reading.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 modeCurr = jpIsKanji(c) || c.charCodeAt(0) === 0x3005 /* noma */ ? '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;
}

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

    let stemLength = 0;
    const shortest = Math.min(source.length, expression.length);
    const sourceHiragana = jpKatakanaToHiragana(source);
    const expressionHiragana = jpKatakanaToHiragana(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 jpDistributeFurigana(stemExpression, stemReading)) {
        output.push(segment);
    }

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

    return output;
}