/*
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MIT License http://www.opensource.org/licenses/mit-license.php
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*/
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"use strict";
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/** @typedef {import("../util/fs").JsonValue} JsonValue */
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// Inspired by https://github.com/npm/json-parse-even-better-errors
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// Remove byte order marker. This catches EF BB BF (the UTF-8 BOM)
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// because the buffer-to-string conversion in `fs.readFileSync()`
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// translates it to FEFF, the UTF-16 BOM.
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/**
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* @param {string | Buffer} txt text
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* @returns {string} text without BOM
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*/
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const stripBOM = (txt) => String(txt).replace(/^\uFEFF/, "");
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class JSONParseError extends SyntaxError {
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/**
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* @param {Error} err err
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* @param {EXPECTED_ANY} raw raw
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* @param {string} txt text
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* @param {number=} context context
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* @param {EXPECTED_FUNCTION=} caller caller
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*/
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constructor(err, raw, txt, context = 20, caller = parseJson) {
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let originalMessage = err.message;
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/** @type {string} */
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let message;
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/** @type {number} */
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let position;
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if (typeof raw !== "string") {
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message = `Cannot parse ${Array.isArray(raw) && raw.length === 0 ? "an empty array" : String(raw)}`;
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position = 0;
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} else if (!txt) {
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message = `${originalMessage} while parsing empty string`;
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position = 0;
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} else {
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// Node 20 puts single quotes around the token and a comma after it
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const UNEXPECTED_TOKEN = /^Unexpected token '?(.)'?(,)? /i;
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const badTokenMatch = originalMessage.match(UNEXPECTED_TOKEN);
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const badIndexMatch = originalMessage.match(/ position\s+(\d+)/i);
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if (badTokenMatch) {
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const h = badTokenMatch[1].charCodeAt(0).toString(16).toUpperCase();
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const hex = `0x${h.length % 2 ? "0" : ""}${h}`;
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originalMessage = originalMessage.replace(
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UNEXPECTED_TOKEN,
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`Unexpected token ${JSON.stringify(badTokenMatch[1])} (${hex})$2 `
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);
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}
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/** @type {number | undefined} */
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let errIdx;
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if (badIndexMatch) {
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errIdx = Number(badIndexMatch[1]);
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} else if (
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// doesn't happen in Node 22+
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/^Unexpected end of JSON.*/i.test(originalMessage)
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) {
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errIdx = txt.length - 1;
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}
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if (errIdx === undefined) {
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message = `${originalMessage} while parsing '${txt.slice(0, context * 2)}'`;
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position = 0;
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} else {
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const start = errIdx <= context ? 0 : errIdx - context;
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const end =
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errIdx + context >= txt.length ? txt.length : errIdx + context;
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const slice = `${start ? "..." : ""}${txt.slice(start, end)}${end === txt.length ? "" : "..."}`;
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message = `${originalMessage} while parsing ${txt === slice ? "" : "near "}${JSON.stringify(slice)}`;
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position = errIdx;
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}
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}
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super(message);
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this.name = "JSONParseError";
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this.systemError = err;
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this.position = position;
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Error.captureStackTrace(this, caller || this.constructor);
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}
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}
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/**
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* @template [R=JsonValue]
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* @callback ParseJsonFn
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* @param {string} raw text
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* @param {(this: EXPECTED_ANY, key: string, value: EXPECTED_ANY) => EXPECTED_ANY=} reviver reviver
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* @returns {R} parsed JSON
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*/
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/** @type {ParseJsonFn} */
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const parseJson = (raw, reviver) => {
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const txt = stripBOM(raw);
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try {
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return JSON.parse(txt, reviver);
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} catch (err) {
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throw new JSONParseError(/** @type {Error} */ (err), raw, txt);
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}
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};
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module.exports = parseJson;
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