unambiguous.js

'use strict'
exports.__esModule = true

const pattern = /(^|;)\s*(export|import)((\s+\w)|(\s*[{*=]))|import\(/m
/**
 * detect possible imports/exports without a full parse.
 *
 * A negative test means that a file is definitely _not_ a module.
 * A positive test means it _could_ be.
 *
 * Not perfect, just a fast way to disqualify large non-ES6 modules and
 * avoid a parse.
 * @type {RegExp}
 */
exports.test = function isMaybeUnambiguousModule(content) {
  return pattern.test(content)
}

// future-/Babel-proof at the expense of being a little loose
const unambiguousNodeType = /^(?:(?:Exp|Imp)ort.*Declaration|TSExportAssignment)$/

/**
 * Given an AST, return true if the AST unambiguously represents a module.
 * @param  {Program node}  ast
 * @return {Boolean}
 */
exports.isModule = function isUnambiguousModule(ast) {
  return ast.body && ast.body.some(node => unambiguousNodeType.test(node.type))
}