polymer-build
Version:
A library of Gulp build tasks
252 lines • 11.2 kB
JavaScript
;
/**
* @license
* Copyright (c) 2018 The Polymer Project Authors. All rights reserved.
* This code may only be used under the BSD style license found at
* http://polymer.github.io/LICENSE.txt
* The complete set of authors may be found at
* http://polymer.github.io/AUTHORS.txt
* The complete set of contributors may be found at
* http://polymer.github.io/CONTRIBUTORS.txt
* Code distributed by Google as part of the polymer project is also
* subject to an additional IP rights grant found at
* http://polymer.github.io/PATENTS.txt
*/
Object.defineProperty(exports, "__esModule", { value: true });
const babelCore = require("@babel/core");
const babylon = require("babylon");
const uuid = require("uuid/v1");
const babel_plugin_bare_specifiers_1 = require("./babel-plugin-bare-specifiers");
const babel_plugin_dynamic_import_amd_1 = require("./babel-plugin-dynamic-import-amd");
const babel_plugin_import_meta_1 = require("./babel-plugin-import-meta");
const externalJs = require("./external-js");
// TODO(aomarks) Switch to babel-preset-env. But how do we get just syntax
// plugins without turning on transformation, for the case where we are
// minifying but not compiling?
// Syntax and transform plugins for ES2015. This is roughly equivalent to
// @babel/preset-es2015, with modules removed and
// @babel/plugin-transform-classes pinned to v7.0.0-beta.35 to avoid
// https://github.com/babel/babel/issues/7506 . As mentioned in the bug, native
// constructors are wrapped with a ES5 'class' which has a constructor that does
// nothing; however, the custom elements polyfill needs the polyfilled
// constructor to be called so that it can supply the element being upgraded as
// the object to use for `this`.
const babelTransformEs2015 = [
require('@babel/plugin-transform-template-literals'),
require('@babel/plugin-transform-literals'),
require('@babel/plugin-transform-function-name'),
require('@babel/plugin-transform-arrow-functions'),
require('@babel/plugin-transform-block-scoped-functions'),
require('@babel/plugin-transform-classes'),
require('@babel/plugin-transform-object-super'),
require('@babel/plugin-transform-shorthand-properties'),
require('@babel/plugin-transform-duplicate-keys'),
require('@babel/plugin-transform-computed-properties'),
require('@babel/plugin-transform-for-of'),
require('@babel/plugin-transform-sticky-regex'),
require('@babel/plugin-transform-unicode-regex'),
require('@babel/plugin-transform-spread'),
require('@babel/plugin-transform-parameters'),
require('@babel/plugin-transform-destructuring'),
require('@babel/plugin-transform-block-scoping'),
require('@babel/plugin-transform-typeof-symbol'),
require('@babel/plugin-transform-instanceof'),
[
require('@babel/plugin-transform-regenerator'),
{ async: false, asyncGenerators: false }
],
];
const babelTransformEs2016 = [
require('@babel/plugin-transform-exponentiation-operator'),
];
const babelTransformEs2017 = [
require('@babel/plugin-transform-async-to-generator'),
];
const babelTransformEs2018 = [
require('@babel/plugin-proposal-object-rest-spread'),
require('@babel/plugin-proposal-async-generator-functions'),
];
// Loading this plugin removes inlined Babel helpers.
const babelExternalHelpersPlugin = require('@babel/plugin-external-helpers');
const babelTransformModulesAmd = [
babel_plugin_dynamic_import_amd_1.dynamicImportAmd,
babel_plugin_import_meta_1.rewriteImportMeta,
require('@babel/plugin-transform-modules-amd'),
];
// We enumerate syntax plugins that would automatically be loaded by our
// transform plugins because we need to support the configuration where we
// minify but don't compile, and don't want Babel to error when it encounters
// syntax that we support when compiling.
const babelSyntaxPlugins = [
// ES2017 and below syntax plugins are included by default.
// ES2018 (partial)
require('@babel/plugin-syntax-object-rest-spread'),
require('@babel/plugin-syntax-async-generators'),
// Future
// require('@babel/plugin-syntax-export-extensions'),
require('@babel/plugin-syntax-dynamic-import'),
require('@babel/plugin-syntax-import-meta'),
];
const babelPresetMinify = require('babel-preset-minify')({}, {
// Disable this or you get `{ err: 'Couldn\'t find intersection' }` now.
// https://github.com/babel/minify/issues/904
builtIns: false,
// Disable the minify-constant-folding plugin because it has a bug relating
// to invalid substitution of constant values into export specifiers:
// https://github.com/babel/minify/issues/820
evaluate: false,
// TODO(aomarks) Find out why we disabled this plugin.
simplifyComparisons: false,
// Prevent removal of things that babel thinks are unreachable, but sometimes
// gets wrong: https://github.com/Polymer/tools/issues/724
deadcode: false,
// Prevents this `isPure` on null problem from blowing up minification.
// https://github.com/babel/minify/issues/790
removeUndefined: false,
// Disable the simplify plugin because it can eat some statements preceeding
// loops. https://github.com/babel/minify/issues/824
simplify: false,
// This is breaking ES6 output. https://github.com/Polymer/tools/issues/261
mangle: false,
});
/**
* Transform some JavaScript according to the given options.
*/
function jsTransform(js, options) {
// Even with no transform plugins, parsing and serializing with Babel will
// make some minor formatting changes to the code. Skip Babel altogether
// if we have no meaningful changes to make.
let doBabelTransform = false;
// Note that Babel plugins run in this order:
// 1) plugins, first to last
// 2) presets, last to first
const plugins = [...babelSyntaxPlugins];
const presets = [];
if (options.externalHelpers) {
plugins.push(babelExternalHelpersPlugin);
}
if (options.minify) {
doBabelTransform = true;
// Minify last, so push first.
presets.push(babelPresetMinify);
}
if (options.compile === true || options.compile === 'es5') {
doBabelTransform = true;
plugins.push(...babelTransformEs2015);
plugins.push(...babelTransformEs2016);
plugins.push(...babelTransformEs2017);
plugins.push(...babelTransformEs2018);
}
else if (options.compile === 'es2015') {
doBabelTransform = true;
plugins.push(...babelTransformEs2016);
plugins.push(...babelTransformEs2017);
plugins.push(...babelTransformEs2018);
}
else if (options.compile === 'es2016') {
doBabelTransform = true;
plugins.push(...babelTransformEs2017);
plugins.push(...babelTransformEs2018);
}
else if (options.compile === 'es2017') {
doBabelTransform = true;
plugins.push(...babelTransformEs2018);
}
if (options.moduleResolution === 'node') {
if (!options.filePath) {
throw new Error('Cannot perform node module resolution without filePath.');
}
doBabelTransform = true;
plugins.push(babel_plugin_bare_specifiers_1.resolveBareSpecifiers(options.filePath, !!options.isComponentRequest, options.packageName, options.componentDir, options.rootDir));
}
// When the AMD option is "auto", these options will change based on whether
// we have a module or not (unless they are already definitely true).
let transformModulesToAmd = options.transformModulesToAmd;
if (transformModulesToAmd === true) {
doBabelTransform = true;
}
const maybeDoBabelTransform = doBabelTransform || transformModulesToAmd === 'auto';
if (maybeDoBabelTransform) {
let ast;
try {
ast = babylon.parse(js, {
// TODO(aomarks) Remove any when typings are updated for babylon 7.
// tslint:disable-next-line: no-any
sourceType: transformModulesToAmd === 'auto' ? 'unambiguous' :
'module',
plugins: [
'asyncGenerators',
'dynamicImport',
// tslint:disable-next-line: no-any
'importMeta',
'objectRestSpread',
],
});
}
catch (e) {
if (options.softSyntaxError && e.constructor.name === 'SyntaxError') {
console.error('ERROR [polymer-build]: failed to parse JavaScript' +
(options.filePath ? ` (${options.filePath}):` : ':'), e);
return js;
}
else {
throw e;
}
}
if (transformModulesToAmd === 'auto' &&
ast.program.sourceType === 'module') {
transformModulesToAmd = true;
}
if (transformModulesToAmd) {
doBabelTransform = true;
plugins.push(...babelTransformModulesAmd);
}
if (doBabelTransform) {
const result = babelCore.transformFromAst(ast, js, { presets, plugins });
if (result.code === undefined) {
throw new Error('Babel transform failed: resulting code was undefined.');
}
js = result.code;
if (!options.externalHelpers && options.compile === 'es5' &&
js.includes('regeneratorRuntime')) {
js = externalJs.getRegeneratorRuntime() + js;
}
}
}
js = replaceTemplateObjectNames(js);
return js;
}
exports.jsTransform = jsTransform;
/**
* Modifies variables names of tagged template literals (`"_templateObject"`)
* from a given string so that they're all unique.
*
* This is needed to workaround a potential naming collision when individually
* transpiled scripts are bundled. See #950.
*/
function replaceTemplateObjectNames(js) {
// Breakdown of regular expression to match "_templateObject" variables
//
// Pattern | Meaning
// -------------------------------------------------------------------
// ( | Group1
// _templateObject | Match "_templateObject"
// \d* | Match 0 or more digits
// \b | Match word boundary
// ) | End Group1
const searchValueRegex = /(_templateObject\d*\b)/g;
// The replacement pattern appends an underscore and UUID to the matches:
//
// Pattern | Meaning
// -------------------------------------------------------------------
// $1 | Insert matching Group1 (from above)
// _ | Insert "_"
// ${uniqueId} | Insert previously generated UUID
const uniqueId = uuid().replace(/-/g, '');
const replaceValue = `$1_${uniqueId}`;
// Example output:
// _templateObject -> _templateObject_200817b1154811e887be8b38cea68555
// _templateObject2 -> _templateObject2_5e44de8015d111e89b203116b5c54903
return js.replace(searchValueRegex, replaceValue);
}
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