class/class_backend/node_modules/browserslist/parse.js

var AND_REGEXP = /^\s+and\s+(.*)/i
var OR_REGEXP = /^(?:,\s*|\s+or\s+)(.*)/i

function flatten(array) {
  if (!Array.isArray(array)) return [array]
  return array.reduce(function (a, b) {
    return a.concat(flatten(b))
  }, [])
}

function find(string, predicate) {
  for (var max = string.length, n = 1; n <= max; n++) {
    var parsed = string.substr(-n, n)
    if (predicate(parsed, n, max)) {
      return string.slice(0, -n)
    }
  }
  return ''
}

function matchQuery(all, query) {
  var node = { query: query }
  if (query.indexOf('not ') === 0) {
    node.not = true
    query = query.slice(4)
  }

  for (var name in all) {
    var type = all[name]
    var match = query.match(type.regexp)
    if (match) {
      node.type = name
      for (var i = 0; i < type.matches.length; i++) {
        node[type.matches[i]] = match[i + 1]
      }
      return node
    }
  }

  node.type = 'unknown'
  return node
}

function matchBlock(all, string, qs) {
  var node
  return find(string, function (parsed, n, max) {
    if (AND_REGEXP.test(parsed)) {
      node = matchQuery(all, parsed.match(AND_REGEXP)[1])
      node.compose = 'and'
      qs.unshift(node)
      return true
    } else if (OR_REGEXP.test(parsed)) {
      node = matchQuery(all, parsed.match(OR_REGEXP)[1])
      node.compose = 'or'
      qs.unshift(node)
      return true
    } else if (n === max) {
      node = matchQuery(all, parsed.trim())
      node.compose = 'or'
      qs.unshift(node)
      return true
    }
    return false
  })
}

module.exports = function parse(all, queries) {
  if (!Array.isArray(queries)) queries = [queries]
  return flatten(
    queries.map(function (block) {
      var qs = []
      do {
        block = matchBlock(all, block, qs)
      } while (block)
      return qs
    })
  )
}