index.js

'use strict'

const { hasOwnProperty } = Object.prototype

const stringify = configure()

// @ts-expect-error
stringify.configure = configure
// @ts-expect-error
stringify.stringify = stringify

// @ts-expect-error
stringify.default = stringify

// @ts-expect-error used for named export
exports.stringify = stringify
// @ts-expect-error used for named export
exports.configure = configure

module.exports = stringify

// eslint-disable-next-line no-control-regex
const strEscapeSequencesRegExp = /[\u0000-\u001f\u0022\u005c\ud800-\udfff]/

// Escape C0 control characters, double quotes, the backslash and every code
// unit with a numeric value in the inclusive range 0xD800 to 0xDFFF.
function strEscape (str) {
  // Some magic numbers that worked out fine while benchmarking with v8 8.0
  if (str.length < 5000 && !strEscapeSequencesRegExp.test(str)) {
    return `"${str}"`
  }
  return JSON.stringify(str)
}

function sort (array, comparator) {
  // Insertion sort is very efficient for small input sizes, but it has a bad
  // worst case complexity. Thus, use native array sort for bigger values.
  if (array.length > 2e2 || comparator) {
    return array.sort(comparator)
  }
  for (let i = 1; i < array.length; i++) {
    const currentValue = array[i]
    let position = i
    while (position !== 0 && array[position - 1] > currentValue) {
      array[position] = array[position - 1]
      position--
    }
    array[position] = currentValue
  }
  return array
}

const typedArrayPrototypeGetSymbolToStringTag =
  Object.getOwnPropertyDescriptor(
    Object.getPrototypeOf(
      Object.getPrototypeOf(
        new Int8Array()
      )
    ),
    Symbol.toStringTag
  ).get

function isTypedArrayWithEntries (value) {
  return typedArrayPrototypeGetSymbolToStringTag.call(value) !== undefined && value.length !== 0
}

function stringifyTypedArray (array, separator, maximumBreadth) {
  if (array.length < maximumBreadth) {
    maximumBreadth = array.length
  }
  const whitespace = separator === ',' ? '' : ' '
  let res = `"0":${whitespace}${array[0]}`
  for (let i = 1; i < maximumBreadth; i++) {
    res += `${separator}"${i}":${whitespace}${array[i]}`
  }
  return res
}

function getCircularValueOption (options) {
  if (hasOwnProperty.call(options, 'circularValue')) {
    const circularValue = options.circularValue
    if (typeof circularValue === 'string') {
      return `"${circularValue}"`
    }
    if (circularValue == null) {
      return circularValue
    }
    if (circularValue === Error || circularValue === TypeError) {
      return {
        toString () {
          throw new TypeError('Converting circular structure to JSON')
        }
      }
    }
    throw new TypeError('The "circularValue" argument must be of type string or the value null or undefined')
  }
  return '"[Circular]"'
}

function getDeterministicOption (options) {
  let value
  if (hasOwnProperty.call(options, 'deterministic')) {
    value = options.deterministic
    if (typeof value !== 'boolean' && typeof value !== 'function') {
      throw new TypeError('The "deterministic" argument must be of type boolean or comparator function')
    }
  }
  return value === undefined ? true : value
}

function getBooleanOption (options, key) {
  let value
  if (hasOwnProperty.call(options, key)) {
    value = options[key]
    if (typeof value !== 'boolean') {
      throw new TypeError(`The "${key}" argument must be of type boolean`)
    }
  }
  return value === undefined ? true : value
}

function getPositiveIntegerOption (options, key) {
  let value
  if (hasOwnProperty.call(options, key)) {
    value = options[key]
    if (typeof value !== 'number') {
      throw new TypeError(`The "${key}" argument must be of type number`)
    }
    if (!Number.isInteger(value)) {
      throw new TypeError(`The "${key}" argument must be an integer`)
    }
    if (value < 1) {
      throw new RangeError(`The "${key}" argument must be >= 1`)
    }
  }
  return value === undefined ? Infinity : value
}

function getItemCount (number) {
  if (number === 1) {
    return '1 item'
  }
  return `${number} items`
}

function getUniqueReplacerSet (replacerArray) {
  const replacerSet = new Set()
  for (const value of replacerArray) {
    if (typeof value === 'string' || typeof value === 'number') {
      replacerSet.add(String(value))
    }
  }
  return replacerSet
}

function getStrictOption (options) {
  if (hasOwnProperty.call(options, 'strict')) {
    const value = options.strict
    if (typeof value !== 'boolean') {
      throw new TypeError('The "strict" argument must be of type boolean')
    }
    if (value) {
      return (value) => {
        let message = `Object can not safely be stringified. Received type ${typeof value}`
        if (typeof value !== 'function') message += ` (${value.toString()})`
        throw new Error(message)
      }
    }
  }
}

function configure (options) {
  options = { ...options }
  const fail = getStrictOption(options)
  if (fail) {
    if (options.bigint === undefined) {
      options.bigint = false
    }
    if (!('circularValue' in options)) {
      options.circularValue = Error
    }
  }
  const circularValue = getCircularValueOption(options)
  const bigint = getBooleanOption(options, 'bigint')
  const deterministic = getDeterministicOption(options)
  const comparator = typeof deterministic === 'function' ? deterministic : undefined
  const maximumDepth = getPositiveIntegerOption(options, 'maximumDepth')
  const maximumBreadth = getPositiveIntegerOption(options, 'maximumBreadth')

  function stringifyFnReplacer (key, parent, stack, replacer, spacer, indentation) {
    let value = parent[key]

    if (typeof value === 'object' && value !== null && typeof value.toJSON === 'function') {
      value = value.toJSON(key)
    }
    value = replacer.call(parent, key, value)

    switch (typeof value) {
      case 'string':
        return strEscape(value)
      case 'object': {
        if (value === null) {
          return 'null'
        }
        if (stack.indexOf(value) !== -1) {
          return circularValue
        }

        let res = ''
        let join = ','
        const originalIndentation = indentation

        if (Array.isArray(value)) {
          if (value.length === 0) {
            return '[]'
          }
          if (maximumDepth < stack.length + 1) {
            return '"[Array]"'
          }
          stack.push(value)
          if (spacer !== '') {
            indentation += spacer
            res += `\n${indentation}`
            join = `,\n${indentation}`
          }
          const maximumValuesToStringify = Math.min(value.length, maximumBreadth)
          let i = 0
          for (; i < maximumValuesToStringify - 1; i++) {
            const tmp = stringifyFnReplacer(String(i), value, stack, replacer, spacer, indentation)
            res += tmp !== undefined ? tmp : 'null'
            res += join
          }
          const tmp = stringifyFnReplacer(String(i), value, stack, replacer, spacer, indentation)
          res += tmp !== undefined ? tmp : 'null'
          if (value.length - 1 > maximumBreadth) {
            const removedKeys = value.length - maximumBreadth - 1
            res += `${join}"... ${getItemCount(removedKeys)} not stringified"`
          }
          if (spacer !== '') {
            res += `\n${originalIndentation}`
          }
          stack.pop()
          return `[${res}]`
        }

        let keys = Object.keys(value)
        const keyLength = keys.length
        if (keyLength === 0) {
          return '{}'
        }
        if (maximumDepth < stack.length + 1) {
          return '"[Object]"'
        }
        let whitespace = ''
        let separator = ''
        if (spacer !== '') {
          indentation += spacer
          join = `,\n${indentation}`
          whitespace = ' '
        }
        const maximumPropertiesToStringify = Math.min(keyLength, maximumBreadth)
        if (deterministic && !isTypedArrayWithEntries(value)) {
          keys = sort(keys, comparator)
        }
        stack.push(value)
        for (let i = 0; i < maximumPropertiesToStringify; i++) {
          const key = keys[i]
          const tmp = stringifyFnReplacer(key, value, stack, replacer, spacer, indentation)
          if (tmp !== undefined) {
            res += `${separator}${strEscape(key)}:${whitespace}${tmp}`
            separator = join
          }
        }
        if (keyLength > maximumBreadth) {
          const removedKeys = keyLength - maximumBreadth
          res += `${separator}"...":${whitespace}"${getItemCount(removedKeys)} not stringified"`
          separator = join
        }
        if (spacer !== '' && separator.length > 1) {
          res = `\n${indentation}${res}\n${originalIndentation}`
        }
        stack.pop()
        return `{${res}}`
      }
      case 'number':
        return isFinite(value) ? String(value) : fail ? fail(value) : 'null'
      case 'boolean':
        return value === true ? 'true' : 'false'
      case 'undefined':
        return undefined
      case 'bigint':
        if (bigint) {
          return String(value)
        }
        // fallthrough
      default:
        return fail ? fail(value) : undefined
    }
  }

  function stringifyArrayReplacer (key, value, stack, replacer, spacer, indentation) {
    if (typeof value === 'object' && value !== null && typeof value.toJSON === 'function') {
      value = value.toJSON(key)
    }

    switch (typeof value) {
      case 'string':
        return strEscape(value)
      case 'object': {
        if (value === null) {
          return 'null'
        }
        if (stack.indexOf(value) !== -1) {
          return circularValue
        }

        const originalIndentation = indentation
        let res = ''
        let join = ','

        if (Array.isArray(value)) {
          if (value.length === 0) {
            return '[]'
          }
          if (maximumDepth < stack.length + 1) {
            return '"[Array]"'
          }
          stack.push(value)
          if (spacer !== '') {
            indentation += spacer
            res += `\n${indentation}`
            join = `,\n${indentation}`
          }
          const maximumValuesToStringify = Math.min(value.length, maximumBreadth)
          let i = 0
          for (; i < maximumValuesToStringify - 1; i++) {
            const tmp = stringifyArrayReplacer(String(i), value[i], stack, replacer, spacer, indentation)
            res += tmp !== undefined ? tmp : 'null'
            res += join
          }
          const tmp = stringifyArrayReplacer(String(i), value[i], stack, replacer, spacer, indentation)
          res += tmp !== undefined ? tmp : 'null'
          if (value.length - 1 > maximumBreadth) {
            const removedKeys = value.length - maximumBreadth - 1
            res += `${join}"... ${getItemCount(removedKeys)} not stringified"`
          }
          if (spacer !== '') {
            res += `\n${originalIndentation}`
          }
          stack.pop()
          return `[${res}]`
        }
        stack.push(value)
        let whitespace = ''
        if (spacer !== '') {
          indentation += spacer
          join = `,\n${indentation}`
          whitespace = ' '
        }
        let separator = ''
        for (const key of replacer) {
          const tmp = stringifyArrayReplacer(key, value[key], stack, replacer, spacer, indentation)
          if (tmp !== undefined) {
            res += `${separator}${strEscape(key)}:${whitespace}${tmp}`
            separator = join
          }
        }
        if (spacer !== '' && separator.length > 1) {
          res = `\n${indentation}${res}\n${originalIndentation}`
        }
        stack.pop()
        return `{${res}}`
      }
      case 'number':
        return isFinite(value) ? String(value) : fail ? fail(value) : 'null'
      case 'boolean':
        return value === true ? 'true' : 'false'
      case 'undefined':
        return undefined
      case 'bigint':
        if (bigint) {
          return String(value)
        }
        // fallthrough
      default:
        return fail ? fail(value) : undefined
    }
  }

  function stringifyIndent (key, value, stack, spacer, indentation) {
    switch (typeof value) {
      case 'string':
        return strEscape(value)
      case 'object': {
        if (value === null) {
          return 'null'
        }
        if (typeof value.toJSON === 'function') {
          value = value.toJSON(key)
          // Prevent calling `toJSON` again.
          if (typeof value !== 'object') {
            return stringifyIndent(key, value, stack, spacer, indentation)
          }
          if (value === null) {
            return 'null'
          }
        }
        if (stack.indexOf(value) !== -1) {
          return circularValue
        }
        const originalIndentation = indentation

        if (Array.isArray(value)) {
          if (value.length === 0) {
            return '[]'
          }
          if (maximumDepth < stack.length + 1) {
            return '"[Array]"'
          }
          stack.push(value)
          indentation += spacer
          let res = `\n${indentation}`
          const join = `,\n${indentation}`
          const maximumValuesToStringify = Math.min(value.length, maximumBreadth)
          let i = 0
          for (; i < maximumValuesToStringify - 1; i++) {
            const tmp = stringifyIndent(String(i), value[i], stack, spacer, indentation)
            res += tmp !== undefined ? tmp : 'null'
            res += join
          }
          const tmp = stringifyIndent(String(i), value[i], stack, spacer, indentation)
          res += tmp !== undefined ? tmp : 'null'
          if (value.length - 1 > maximumBreadth) {
            const removedKeys = value.length - maximumBreadth - 1
            res += `${join}"... ${getItemCount(removedKeys)} not stringified"`
          }
          res += `\n${originalIndentation}`
          stack.pop()
          return `[${res}]`
        }

        let keys = Object.keys(value)
        const keyLength = keys.length
        if (keyLength === 0) {
          return '{}'
        }
        if (maximumDepth < stack.length + 1) {
          return '"[Object]"'
        }
        indentation += spacer
        const join = `,\n${indentation}`
        let res = ''
        let separator = ''
        let maximumPropertiesToStringify = Math.min(keyLength, maximumBreadth)
        if (isTypedArrayWithEntries(value)) {
          res += stringifyTypedArray(value, join, maximumBreadth)
          keys = keys.slice(value.length)
          maximumPropertiesToStringify -= value.length
          separator = join
        }
        if (deterministic) {
          keys = sort(keys, comparator)
        }
        stack.push(value)
        for (let i = 0; i < maximumPropertiesToStringify; i++) {
          const key = keys[i]
          const tmp = stringifyIndent(key, value[key], stack, spacer, indentation)
          if (tmp !== undefined) {
            res += `${separator}${strEscape(key)}: ${tmp}`
            separator = join
          }
        }
        if (keyLength > maximumBreadth) {
          const removedKeys = keyLength - maximumBreadth
          res += `${separator}"...": "${getItemCount(removedKeys)} not stringified"`
          separator = join
        }
        if (separator !== '') {
          res = `\n${indentation}${res}\n${originalIndentation}`
        }
        stack.pop()
        return `{${res}}`
      }
      case 'number':
        return isFinite(value) ? String(value) : fail ? fail(value) : 'null'
      case 'boolean':
        return value === true ? 'true' : 'false'
      case 'undefined':
        return undefined
      case 'bigint':
        if (bigint) {
          return String(value)
        }
        // fallthrough
      default:
        return fail ? fail(value) : undefined
    }
  }

  function stringifySimple (key, value, stack) {
    switch (typeof value) {
      case 'string':
        return strEscape(value)
      case 'object': {
        if (value === null) {
          return 'null'
        }
        if (typeof value.toJSON === 'function') {
          value = value.toJSON(key)
          // Prevent calling `toJSON` again
          if (typeof value !== 'object') {
            return stringifySimple(key, value, stack)
          }
          if (value === null) {
            return 'null'
          }
        }
        if (stack.indexOf(value) !== -1) {
          return circularValue
        }

        let res = ''

        const hasLength = value.length !== undefined
        if (hasLength && Array.isArray(value)) {
          if (value.length === 0) {
            return '[]'
          }
          if (maximumDepth < stack.length + 1) {
            return '"[Array]"'
          }
          stack.push(value)
          const maximumValuesToStringify = Math.min(value.length, maximumBreadth)
          let i = 0
          for (; i < maximumValuesToStringify - 1; i++) {
            const tmp = stringifySimple(String(i), value[i], stack)
            res += tmp !== undefined ? tmp : 'null'
            res += ','
          }
          const tmp = stringifySimple(String(i), value[i], stack)
          res += tmp !== undefined ? tmp : 'null'
          if (value.length - 1 > maximumBreadth) {
            const removedKeys = value.length - maximumBreadth - 1
            res += `,"... ${getItemCount(removedKeys)} not stringified"`
          }
          stack.pop()
          return `[${res}]`
        }

        let keys = Object.keys(value)
        const keyLength = keys.length
        if (keyLength === 0) {
          return '{}'
        }
        if (maximumDepth < stack.length + 1) {
          return '"[Object]"'
        }
        let separator = ''
        let maximumPropertiesToStringify = Math.min(keyLength, maximumBreadth)
        if (hasLength && isTypedArrayWithEntries(value)) {
          res += stringifyTypedArray(value, ',', maximumBreadth)
          keys = keys.slice(value.length)
          maximumPropertiesToStringify -= value.length
          separator = ','
        }
        if (deterministic) {
          keys = sort(keys, comparator)
        }
        stack.push(value)
        for (let i = 0; i < maximumPropertiesToStringify; i++) {
          const key = keys[i]
          const tmp = stringifySimple(key, value[key], stack)
          if (tmp !== undefined) {
            res += `${separator}${strEscape(key)}:${tmp}`
            separator = ','
          }
        }
        if (keyLength > maximumBreadth) {
          const removedKeys = keyLength - maximumBreadth
          res += `${separator}"...":"${getItemCount(removedKeys)} not stringified"`
        }
        stack.pop()
        return `{${res}}`
      }
      case 'number':
        return isFinite(value) ? String(value) : fail ? fail(value) : 'null'
      case 'boolean':
        return value === true ? 'true' : 'false'
      case 'undefined':
        return undefined
      case 'bigint':
        if (bigint) {
          return String(value)
        }
        // fallthrough
      default:
        return fail ? fail(value) : undefined
    }
  }

  function stringify (value, replacer, space) {
    if (arguments.length > 1) {
      let spacer = ''
      if (typeof space === 'number') {
        spacer = ' '.repeat(Math.min(space, 10))
      } else if (typeof space === 'string') {
        spacer = space.slice(0, 10)
      }
      if (replacer != null) {
        if (typeof replacer === 'function') {
          return stringifyFnReplacer('', { '': value }, [], replacer, spacer, '')
        }
        if (Array.isArray(replacer)) {
          return stringifyArrayReplacer('', value, [], getUniqueReplacerSet(replacer), spacer, '')
        }
      }
      if (spacer.length !== 0) {
        return stringifyIndent('', value, [], spacer, '')
      }
    }
    return stringifySimple('', value, [])
  }

  return stringify
}