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refactor(utils/lyrics): support multi-timestamp lyrics (#1268)

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* refactor(utils/lyrics): support multi-timestamp lyrics

Fully rewrited and improved the performance.

* refactor(utils/lyrics): remove useless .map

* fix(utils/lyrics): enhance the extraction logic
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pan93412 2022-01-27 16:25:45 +08:00 committed by GitHub
parent 7b7b8745b6
commit 8a6c13e62f
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1 changed files with 60 additions and 22 deletions
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82
src/utils/lyrics.js
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@ -7,38 +7,76 @@ export function lyricParser(lrc) {
};
}
const extractTimeRegex = /^(?<rawTime>\[(?<min>\d+):(?<sec>\d+)(?:\.|:)(?<ms>\d+)\])\s*(?<content>.+)$/;
// regexr.com/6e52n
const extractLrcRegex = /^(?<lyricTimestamps>(?:\[.+?\])+)(?!\[)(?<content>.+)$/gm;
const extractTimestampRegex = /\[(?<min>\d+):(?<sec>\d+)(?:\.|:)(?<ms>\d+)\]/g;
/**
* @typedef {{time: number, rawTime: string, content: string}} ParsedLyric
*/
/**
* Parse the lyric string.
*
* @param {string} lrc The `lrc` input.
* @returns {ParsedLyric[]} The parsed lyric.
* @example parseLyric("[00:00.00] Hello, World!\n[00:00.10] Test\n");
*/
function parseLyric(lrc) {
const lyrics = lrc.trim().split('\n');
/**
* A sorted list of parsed lyric and its timestamp.
*
* @type {ParsedLyric[]}
* @see binarySearch
*/
const parsedLyrics = [];
const parsedLyrics = lyrics
.map((/** @type {string} */ line) => {
try {
const extractedLyric = extractTimeRegex.exec(line);
/**
* Find the appropriate index to push our parsed lyric.
* @param {ParsedLyric} lyric
*/
const binarySearch = lyric => {
let time = lyric.time;
// If this line is not a lyric.
if (!extractedLyric) throw 'This line is not a valid lyric.';
let low = 0;
let high = parsedLyrics.length - 1;
// Otherwise, we extract the lyric part.
const { rawTime, min, sec, ms, content } = extractedLyric.groups;
const time = Number(min) * 60 + Number(sec) + 0.01 * Number(ms);
return {
time,
rawTime,
content: trimContent(content),
};
} catch (e) {
console.debug(`lyrics.js: Failed to extract "${line}". ${e}`);
while (low <= high) {
const mid = Math.floor((low + high) / 2);
const midTime = parsedLyrics[mid].time;
if (midTime === time) {
return mid;
} else if (midTime < time) {
low = mid + 1;
} else {
high = mid - 1;
}
})
.filter(response => !!response) // remove "undefined" entries
.sort((a, b) => a.time - b.time);
}
return low;
};
for (const line of lrc.trim().matchAll(extractLrcRegex)) {
const { lyricTimestamps, content } = line.groups;
for (const timestamp of lyricTimestamps.matchAll(extractTimestampRegex)) {
const { min, sec, ms } = timestamp.groups;
const rawTime = timestamp[0];
const time = Number(min) * 60 + Number(sec) + 0.001 * Number(ms);
/** @type {ParsedLyric} */
const parsedLyric = { rawTime, time, content: trimContent(content) };
parsedLyrics.splice(binarySearch(parsedLyric), 0, parsedLyric);
}
}
return parsedLyrics;
}
/**
* @param {string} content
* @returns {string}
*/
function trimContent(content) {
let t = content.trim();
return t.length < 1 ? content : t;