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