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/*
* Copyright (C) 2023-2024 Yomitan Authors
* Copyright (C) 2021-2022 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/>.
*/
/**
* This class provides some general utility functions for regular expressions.
*/
export class RegexUtil {
/** @type {RegExp} @readonly */
static _matchReplacementPattern = /\$(?:\$|&|`|'|(\d\d?)|<([^>]*)>)/g;
/**
* Applies string.replace using a regular expression and replacement string as arguments.
* A source map of the changes is also maintained.
* @param {string} text A string of the text to replace.
* @param {import('./text-source-map.js').TextSourceMap} sourceMap An instance of `TextSourceMap` which corresponds to `text`.
* @param {RegExp} pattern A regular expression to use as the replacement.
* @param {string} replacement A replacement string that follows the format of the standard
* JavaScript regular expression replacement string.
* @returns {string} A new string with the pattern replacements applied and the source map updated.
*/
static applyTextReplacement(text, sourceMap, pattern, replacement) {
const isGlobal = pattern.global;
if (isGlobal) { pattern.lastIndex = 0; }
for (let loop = true; loop; loop = isGlobal) {
const match = pattern.exec(text);
if (match === null) { break; }
const matchText = match[0];
const index = match.index;
const actualReplacement = this.applyMatchReplacement(replacement, match);
const actualReplacementLength = actualReplacement.length;
const delta = actualReplacementLength - (matchText.length > 0 ? matchText.length : -1);
text = `${text.substring(0, index)}${actualReplacement}${text.substring(index + matchText.length)}`;
pattern.lastIndex += delta;
if (actualReplacementLength > 0) {
sourceMap.insert(index, ...(new Array(actualReplacementLength).fill(0)));
sourceMap.combine(index - 1 + actualReplacementLength, matchText.length);
} else {
sourceMap.combine(index, matchText.length);
}
}
return text;
}
/**
* Applies the replacement string for a given regular expression match.
* @param {string} replacement The replacement string that follows the format of the standard
* JavaScript regular expression replacement string.
* @param {RegExpMatchArray} match A match object returned from RegExp.match.
* @returns {string} A new string with the pattern replacement applied.
*/
static applyMatchReplacement(replacement, match) {
const pattern = this._matchReplacementPattern;
pattern.lastIndex = 0;
return replacement.replace(pattern, (g0, g1, g2) => {
if (typeof g1 !== 'undefined') {
const matchIndex = Number.parseInt(g1, 10);
if (matchIndex >= 1 && matchIndex <= match.length) {
return match[matchIndex];
}
} else if (typeof g2 !== 'undefined') {
const {groups} = match;
if (typeof groups === 'object' && groups !== null && Object.prototype.hasOwnProperty.call(groups, g2)) {
return groups[g2];
}
} else {
let {index} = match;
if (typeof index !== 'number') { index = 0; }
switch (g0) {
case '$': return '$';
case '&': return match[0];
case '`': return replacement.substring(0, index);
case '\'': return replacement.substring(index + g0.length);
}
}
return g0;
});
}
}
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