@dbl0null/slow-json-stringify/src/_utils.mjs

The slow.. well actually fastest JSON stringifier in the galaxy.

/**
 * `_find` is a super fast deep property finder.
 * It dynamically build the function needed to reach the desired
 * property.
 *
 * e.g.
 * obj = {a: {b: {c: 1}}}
 * _find(['a','b','c']) => (obj) => (((obj || {}).a || {}).b || {}).c
 *
 * @param {array} path - path to reach object property.
 */
const _find = path => {
  let str = 'obj'

  for (let i = 0; i < path.length; ++i) {
    str = `(${str}||{}).${path[i]}`
  }

  return eval(`(obj => ${str})`)
}

const __find = path => {
  let str = 'obj'

  for (let i = 0; i < path.length; ++i) {
    str += `?.['${path[i]}']`
  }

  return eval(`(obj => ${str})`)
}

function _arraySerializer (serializer, array) {
  // Stringifying more complex array using the provided sjs schema
  let acc = ''
  const len = array.length - 1
  for (let i = 0; i < len; ++i) {
    acc += `${serializer(array[i])},`
  }

  // Prevent slice for removing unnecessary comma.
  acc += serializer(array[len])
  return `[${acc}]`
}

/**
 * `_makeArraySerializer` is simply a wrapper of another `sjs` schema
 * used for the serialization of arrais.
 */
const _makeArraySerializer = serializer => {
  if (typeof serializer === 'function') return _arraySerializer.bind(this, serializer)
  return JSON.stringify
}

const TYPES = ['number', 'string', 'boolean', 'array', 'null']

/* #__PURE__ */
function checkType (type) {
  if (typeof process !== 'undefined' && process.env.NODE_ENV !== 'production' && !TYPES.includes(type)) {
    throw new Error(
      `Expected one of: "number", "string", "boolean", "array", "null". received "${type}" instead`
    )
  }
}

const fnUser = value => value

/**
 * @param type number|string|boolean|array|null
 * @param serializer
 * @returns
 */
const attr = (type, serializer) => {
  /* #__PURE__ */
  checkType(type)

  const usedSerializer = serializer || fnUser

  return {
    isSJS: true,
    type,
    serializer:
      type === 'array' ? _makeArraySerializer(serializer) : usedSerializer
  }
}

// Little utility for escaping convenience.
// => if no regex is provided, a default one will be used.
const _defaultRegex = /[\t\n\r"\\]/g
const _escapeCallback = char => '\\' + char
const escape = (regex = _defaultRegex) => str => str.replace(regex, _escapeCallback)

export { __find, _find, escape, attr }