Last change
on this file since ceaed42 was 6a3a178, checked in by Ema <ema_spirova@…>, 3 years ago |
initial commit
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Property mode
set to
100644
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File size:
713 bytes
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1 | function con(n) {
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2 | return 0x80 | (n & 0x3f);
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3 | }
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4 |
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5 | export function encode(str) {
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6 | const arr = str.split("").map(x => x.charCodeAt(0));
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7 | return _encode(arr);
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8 | }
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9 |
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10 | function _encode(arr) {
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11 | if (arr.length === 0) {
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12 | return [];
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13 | }
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14 |
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15 | const [n, ...ns] = arr;
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16 |
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17 | if (n < 0) {
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18 | throw new Error("utf8");
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19 | }
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20 |
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21 | if (n < 0x80) {
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22 | return [n, ..._encode(ns)];
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23 | }
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24 |
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25 | if (n < 0x800) {
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26 | return [0xc0 | (n >>> 6), con(n), ..._encode(ns)];
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27 | }
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28 |
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29 | if (n < 0x10000) {
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30 | return [0xe0 | (n >>> 12), con(n >>> 6), con(n), ..._encode(ns)];
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31 | }
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32 |
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33 | if (n < 0x110000) {
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34 | return [
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35 | 0xf0 | (n >>> 18),
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36 | con(n >>> 12),
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37 | con(n >>> 6),
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38 | con(n),
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39 | ..._encode(ns)
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40 | ];
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41 | }
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42 |
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43 | throw new Error("utf8");
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44 | }
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