'use strict'
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const INDENT = Symbol.for('indent')
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const NEWLINE = Symbol.for('newline')
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const DEFAULT_NEWLINE = '\n'
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const DEFAULT_INDENT = ' '
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const BOM = /^\uFEFF/
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// only respect indentation if we got a line break, otherwise squash it
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// things other than objects and arrays aren't indented, so ignore those
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// Important: in both of these regexps, the $1 capture group is the newline
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// or undefined, and the $2 capture group is the indent, or undefined.
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const FORMAT = /^\s*[{[]((?:\r?\n)+)([\s\t]*)/
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const EMPTY = /^(?:\{\}|\[\])((?:\r?\n)+)?$/
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// Node 20 puts single quotes around the token and a comma after it
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const UNEXPECTED_TOKEN = /^Unexpected token '?(.)'?(,)? /i
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const hexify = (char) => {
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const h = char.charCodeAt(0).toString(16).toUpperCase()
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return `0x${h.length % 2 ? '0' : ''}${h}`
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}
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// Remove byte order marker. This catches EF BB BF (the UTF-8 BOM)
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// because the buffer-to-string conversion in `fs.readFileSync()`
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// translates it to FEFF, the UTF-16 BOM.
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const stripBOM = (txt) => String(txt).replace(BOM, '')
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const makeParsedError = (msg, parsing, position = 0) => ({
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message: `${msg} while parsing ${parsing}`,
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position,
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})
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const parseError = (e, txt, context = 20) => {
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let msg = e.message
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if (!txt) {
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return makeParsedError(msg, 'empty string')
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}
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const badTokenMatch = msg.match(UNEXPECTED_TOKEN)
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const badIndexMatch = msg.match(/ position\s+(\d+)/i)
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if (badTokenMatch) {
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msg = msg.replace(
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UNEXPECTED_TOKEN,
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`Unexpected token ${JSON.stringify(badTokenMatch[1])} (${hexify(badTokenMatch[1])})$2 `
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)
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}
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let errIdx
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if (badIndexMatch) {
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errIdx = +badIndexMatch[1]
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} else /* istanbul ignore next - doesnt happen in Node 22 */ if (
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msg.match(/^Unexpected end of JSON.*/i)
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) {
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errIdx = txt.length - 1
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}
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if (errIdx == null) {
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return makeParsedError(msg, `'${txt.slice(0, context * 2)}'`)
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}
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const start = errIdx <= context ? 0 : errIdx - context
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const end = errIdx + context >= txt.length ? txt.length : errIdx + context
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const slice = `${start ? '...' : ''}${txt.slice(start, end)}${end === txt.length ? '' : '...'}`
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return makeParsedError(
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msg,
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`${txt === slice ? '' : 'near '}${JSON.stringify(slice)}`,
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errIdx
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)
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}
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class JSONParseError extends SyntaxError {
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constructor (er, txt, context, caller) {
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const metadata = parseError(er, txt, context)
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super(metadata.message)
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Object.assign(this, metadata)
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this.code = 'EJSONPARSE'
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this.systemError = er
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Error.captureStackTrace(this, caller || this.constructor)
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}
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get name () {
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return this.constructor.name
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}
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set name (n) {}
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get [Symbol.toStringTag] () {
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return this.constructor.name
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}
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}
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const parseJson = (txt, reviver) => {
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const result = JSON.parse(txt, reviver)
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if (result && typeof result === 'object') {
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// get the indentation so that we can save it back nicely
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// if the file starts with {" then we have an indent of '', ie, none
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// otherwise, pick the indentation of the next line after the first \n If the
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// pattern doesn't match, then it means no indentation. JSON.stringify ignores
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// symbols, so this is reasonably safe. if the string is '{}' or '[]', then
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// use the default 2-space indent.
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const match = txt.match(EMPTY) || txt.match(FORMAT) || [null, '', '']
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result[NEWLINE] = match[1] ?? DEFAULT_NEWLINE
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result[INDENT] = match[2] ?? DEFAULT_INDENT
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}
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return result
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}
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const parseJsonError = (raw, reviver, context) => {
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const txt = stripBOM(raw)
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try {
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return parseJson(txt, reviver)
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} catch (e) {
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if (typeof raw !== 'string' && !Buffer.isBuffer(raw)) {
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const msg = Array.isArray(raw) && raw.length === 0 ? 'an empty array' : String(raw)
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throw Object.assign(
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new TypeError(`Cannot parse ${msg}`),
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{ code: 'EJSONPARSE', systemError: e }
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)
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}
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throw new JSONParseError(e, txt, context, parseJsonError)
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}
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}
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module.exports = parseJsonError
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parseJsonError.JSONParseError = JSONParseError
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parseJsonError.noExceptions = (raw, reviver) => {
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try {
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return parseJson(stripBOM(raw), reviver)
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} catch {
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// no exceptions
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}
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}
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