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1'use strict'
2
3module.exports = parseJson
4function parseJson (txt, reviver, context) {
5  context = context || 20
6  try {
7    return JSON.parse(txt, reviver)
8  } catch (e) {
9    if (typeof txt !== 'string') {
10      const isEmptyArray = Array.isArray(txt) && txt.length === 0
11      const errorMessage = 'Cannot parse ' +
12      (isEmptyArray ? 'an empty array' : String(txt))
13      throw new TypeError(errorMessage)
14    }
15    const syntaxErr = e.message.match(/^Unexpected token.*position\s+(\d+)/i)
16    const errIdx = syntaxErr
17    ? +syntaxErr[1]
18    : e.message.match(/^Unexpected end of JSON.*/i)
19    ? txt.length - 1
20    : null
21    if (errIdx != null) {
22      const start = errIdx <= context
23      ? 0
24      : errIdx - context
25      const end = errIdx + context >= txt.length
26      ? txt.length
27      : errIdx + context
28      e.message += ` while parsing near '${
29        start === 0 ? '' : '...'
30      }${txt.slice(start, end)}${
31        end === txt.length ? '' : '...'
32      }'`
33    } else {
34      e.message += ` while parsing '${txt.slice(0, context * 2)}'`
35    }
36    throw e
37  }
38}
39