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121 lines
3.8 KiB
121 lines
3.8 KiB
'use strict' |
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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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const parseError = (e, txt, context) => { |
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if (!txt) { |
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return { |
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message: e.message + ' while parsing empty string', |
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position: 0, |
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} |
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} |
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const badToken = e.message.match(/^Unexpected token (.) .*position\s+(\d+)/i) |
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const errIdx = badToken ? +badToken[2] |
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: e.message.match(/^Unexpected end of JSON.*/i) ? txt.length - 1 |
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: null |
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const msg = badToken ? e.message.replace(/^Unexpected token ./, `Unexpected token ${ |
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JSON.stringify(badToken[1]) |
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} (${hexify(badToken[1])})`) |
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: e.message |
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if (errIdx !== null && errIdx !== undefined) { |
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const start = errIdx <= context ? 0 |
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: errIdx - context |
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const end = errIdx + context >= txt.length ? txt.length |
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: errIdx + context |
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const slice = (start === 0 ? '' : '...') + |
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txt.slice(start, end) + |
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(end === txt.length ? '' : '...') |
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const near = txt === slice ? '' : 'near ' |
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return { |
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message: msg + ` while parsing ${near}${JSON.stringify(slice)}`, |
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position: errIdx, |
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} |
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} else { |
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return { |
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message: msg + ` while parsing '${txt.slice(0, context * 2)}'`, |
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position: 0, |
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} |
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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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context = context || 20 |
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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 () { return this.constructor.name } |
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set name (n) {} |
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get [Symbol.toStringTag] () { return this.constructor.name } |
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} |
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const kIndent = Symbol.for('indent') |
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const kNewline = Symbol.for('newline') |
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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 formatRE = /^\s*[{\[]((?:\r?\n)+)([\s\t]*)/ |
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const emptyRE = /^(?:\{\}|\[\])((?:\r?\n)+)?$/ |
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const parseJson = (txt, reviver, context) => { |
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const parseText = stripBOM(txt) |
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context = context || 20 |
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try { |
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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 |
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// If the pattern doesn't match, then it means no indentation. |
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// JSON.stringify ignores symbols, so this is reasonably safe. |
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// if the string is '{}' or '[]', then use the default 2-space indent. |
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const [, newline = '\n', indent = ' '] = parseText.match(emptyRE) || |
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parseText.match(formatRE) || |
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[, '', ''] |
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const result = JSON.parse(parseText, reviver) |
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if (result && typeof result === 'object') { |
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result[kNewline] = newline |
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result[kIndent] = indent |
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} |
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return result |
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} catch (e) { |
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if (typeof txt !== 'string' && !Buffer.isBuffer(txt)) { |
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const isEmptyArray = Array.isArray(txt) && txt.length === 0 |
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throw Object.assign(new TypeError( |
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`Cannot parse ${isEmptyArray ? 'an empty array' : String(txt)}` |
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), { |
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code: 'EJSONPARSE', |
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systemError: e, |
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}) |
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} |
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throw new JSONParseError(e, parseText, context, parseJson) |
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} |
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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(/^\uFEFF/, '') |
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module.exports = parseJson |
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parseJson.JSONParseError = JSONParseError |
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parseJson.noExceptions = (txt, reviver) => { |
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try { |
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return JSON.parse(stripBOM(txt), reviver) |
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} catch (e) {} |
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}
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