source: node_modules/autoprefixer/lib/utils.js@ 2058e5c

let { list } = require('postcss')

/**
 * Throw special error, to tell beniary,
 * that this error is from Autoprefixer.
 */
module.exports.error = function (text) {
  let err = new Error(text)
  err.autoprefixer = true
  throw err
}

/**
 * Return array, that doesn’t contain duplicates.
 */
module.exports.uniq = function (array) {
  return [...new Set(array)]
}

/**
 * Return "-webkit-" on "-webkit- old"
 */
module.exports.removeNote = function (string) {
  if (!string.includes(' ')) {
    return string
  }

  return string.split(' ')[0]
}

/**
 * Escape RegExp symbols
 */
module.exports.escapeRegexp = function (string) {
  return string.replace(/[$()*+-.?[\\\]^{|}]/g, '\\$&')
}

/**
 * Return regexp to check, that CSS string contain word
 */
module.exports.regexp = function (word, escape = true) {
  if (escape) {
    word = this.escapeRegexp(word)
  }
  return new RegExp(`(^|[\\s,(])(${word}($|[\\s(,]))`, 'gi')
}

/**
 * Change comma list
 */
module.exports.editList = function (value, callback) {
  let origin = list.comma(value)
  let changed = callback(origin, [])

  if (origin === changed) {
    return value
  }

  let join = value.match(/,\s*/)
  join = join ? join[0] : ', '
  return changed.join(join)
}

/**
 * Split the selector into parts.
 * It returns 3 level deep array because selectors can be comma
 * separated (1), space separated (2), and combined (3)
 * @param {String} selector selector string
 * @return {Array<Array<Array>>} 3 level deep array of split selector
 * @see utils.test.js for examples
 */
module.exports.splitSelector = function (selector) {
  return list.comma(selector).map(i => {
    return list.space(i).map(k => {
      return k.split(/(?=\.|#)/g)
    })
  })
}

/**
 * Return true if a given value only contains numbers.
 * @param {*} value
 * @returns {boolean}
 */
module.exports.isPureNumber = function (value) {
  if (typeof value === 'number') {
    return true
  }
  if (typeof value === 'string') {
    return /^[0-9]+$/.test(value)
  }
  return false
}