babel-plugin-transform-imports-api/src/transformImport.ts

Convert import default package API to modular reference to reduce package size and transforms member style imports.

/** forked by https://bitbucket.org/amctheatres/babel-transform-imports/src/master/index.js */
import * as isInvalidPath from 'is-invalid-path'
import * as pathLib from 'path'

// 更改插件 state.opts 为 babel-transform-imports 插件的 state.opts
const proxyOptKey = 'packagesImport'

function findOptionFromSource(source, state) {
  var opts = state.opts[proxyOptKey]
  if (opts[source]) return source

  var opt = Object.keys(opts).find(function (key) {
    return isInvalidPath(key) && new RegExp(key).test(source)
  })
  if (opt) return opt

  var isRelativePath = source.match(/^\.{0,2}\//)
  // This block handles relative paths, such as ./components, ../../components, etc.
  if (isRelativePath) {
    var dirname = source[0] === '/' ? '' : state.file.opts.filename ? pathLib.dirname(state.file.opts.filename) : '.'
    var _source = pathLib.resolve(pathLib.join(dirname, source))

    if (opts[_source]) {
      return _source
    }
  }
}

function getMatchesFromSource(opt, source) {
  var regex = new RegExp(opt, 'g')
  var matches = []
  var m
  while ((m = regex.exec(source)) !== null) {
    if (m.index === regex.lastIndex) regex.lastIndex++
    m.forEach(function (match) {
      // @ts-ignore
      matches.push(match)
    })
  }
  return matches
}

function barf(msg) {
  throw new Error('babel-plugin-transform-imports: ' + msg)
}

function transform(transformOption, importName, matches) {
  if (typeof transformOption === 'function') {
    return transformOption(importName, matches)
  }

  return transformOption.replace(/\$\{\s?([\w\d]*)\s?\}/ig, function (str, g1) {
    if (g1 === 'member') return importName
    return matches[g1]
  })
}

export default function transformImport (path, state, types) {
  // https://github.com/babel/babel/tree/master/packages/babel-types#timportdeclarationspecifiers-source

  // path.node has properties 'source' and 'specifiers' attached.
  // path.node.source is the library/module name, aka 'react-bootstrap'.
  // path.node.specifiers is an array of ImportSpecifier | ImportDefaultSpecifier | ImportNamespaceSpecifier

  var source = path.node.source.value

  var opt = findOptionFromSource(source, state)
  var isRegexp = opt && isInvalidPath(opt)
  var opts = state.opts[proxyOptKey][opt]
  var hasOpts = !!opts

  if (hasOpts) {
    if (!opts.transform) {
      barf('transform option is required for module ' + source)
    }

    var transforms = []

    var fullImports = path.node.specifiers.filter(function (specifier) { return specifier.type !== 'ImportSpecifier' })
    var memberImports = path.node.specifiers.filter(function (specifier) { return specifier.type === 'ImportSpecifier' })

    if (fullImports.length > 0) {
      // Examples of "full" imports:
      //      import * as name from 'module'; (ImportNamespaceSpecifier)
      //      import name from 'module'; (ImportDefaultSpecifier)

      if (opts.preventFullImport) {
        barf('import of entire module ' + source + ' not allowed due to preventFullImport setting')
      }

      if (memberImports.length > 0) {
        // Swap out the import with one that doesn't include member imports.  Member imports should each get their own import line
        // transform this:
        //      import Bootstrap, { Grid } from 'react-bootstrap';
        // into this:
        //      import Bootstrap from 'react-bootstrap';
        // @ts-ignore
        transforms.push(types.importDeclaration(fullImports, types.stringLiteral(source)))
      }
    }

    var matches = isRegexp ? getMatchesFromSource(opt, source) : []

    memberImports.forEach(function (memberImport) {
      // Examples of member imports:
      //      import { member } from 'module'; (ImportSpecifier)
      //      import { member as alias } from 'module' (ImportSpecifier)

      // transform this:
      //      import { Grid as gird } from 'react-bootstrap';
      // into this:
      //      import gird from 'react-bootstrap/lib/Grid';
      // or this, if skipDefaultConversion = true:
      //      import { Grid as gird } from 'react-bootstrap/lib/Grid';

      var importName = memberImport.imported.name

      var replace = transform(opts.transform, importName, matches)

      var newImportSpecifier = (opts.skipDefaultConversion)
        ? memberImport
        : types.importDefaultSpecifier(types.identifier(memberImport.local.name))
      // @ts-ignore
      transforms.push(types.importDeclaration(
        [newImportSpecifier],
        types.stringLiteral(replace)
      ))
    })

    if (transforms.length > 0) {
      path.replaceWithMultiple(transforms)
    }
  }
}