/* * 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; }); } }