Remove __pdfjsdev_webpack__, use webpack options

`__pdfjsdev_webpack__` was used to skip evaluating part of an AST,
in order to not mangle some `require` symbols.
This commit removes `__pdfjsdev_webpack__`, and:

- Uses `__non_webpack_require__` when one wants the output to
  contain `require` instead of `__webpack_require__`.
- Adds options to the webpack config to prevent "polyfills" for
  some Node.js-specific APIs to be added.
- Use `// eslint-disable-next-line no-undef` instead of `/* globals ... */`
  for variables that are not meant to be used globally.

external/webpack/block-require.js

@@ -1,50 +0,0 @@
-/* Copyright 2017 Mozilla Foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-/* eslint-env node */
-
-'use strict';
-
-function isPDFJSDevCheck(test) {
-  // Is it something like `typeof __pdfjsdev_webpack__ === 'undefined'`?
-  return test.type === 'BinaryExpression' &&
-         (test.operator === '===' || test.operator === '!==' ||
-          test.operator === '==' || test.operator === '!=') &&
-         test.left.type === 'UnaryExpression' &&
-         test.left.operator === 'typeof' &&
-         test.left.argument.type === 'Identifier' &&
-         test.left.argument.name === '__pdfjsdev_webpack__' &&
-         test.right.type === 'Literal' && test.right.value === 'undefined';
-}
-
-function isPDFJSDevEnabled(test) {
-  return test.operator[0] === '!';
-}
-
-function BlockRequirePlugin() {}
-
-BlockRequirePlugin.prototype.apply = function(compiler) {
-  compiler.plugin('compilation', function(compilation, data) {
-    data.normalModuleFactory.plugin('parser', function (parser, options) {
-      parser.plugin('statement if', function (ifNode) {
-        if (isPDFJSDevCheck(ifNode.test)) {
-          return isPDFJSDevEnabled(ifNode.test);
-        }
-        return undefined;
-      });
-    });
-  });
-};
-
-module.exports = BlockRequirePlugin;

gulpfile.js

@@ -121,7 +121,6 @@ function createStringSource(filename, content) {
 
 function createWebpackConfig(defines, output) {
   var path = require('path');
-  var BlockRequirePlugin = require('./external/webpack/block-require.js');
 
   var versionInfo = getVersionJSON();
   var bundleDefines = builder.merge(defines, {
@@ -138,7 +137,6 @@ function createWebpackConfig(defines, output) {
     output: output,
     plugins: [
       new webpack2.BannerPlugin({ banner: licenseHeader, raw: true, }),
-      new BlockRequirePlugin()
     ],
     resolve: {
       alias: {
@@ -168,6 +166,19 @@ function createWebpackConfig(defines, output) {
         },
       ],
     },
+    // Avoid shadowing actual Node.js variables with polyfills, by disabling
+    // polyfills/mocks - https://webpack.js.org/configuration/node/
+    node: {
+      console: false,
+      global: false,
+      process: false,
+      __filename: false,
+      __dirname: false,
+      Buffer: false,
+      setImmediate: false,
+    },
+    // If we upgrade to Webpack 3.0+, the above can be replaced with:
+    // node: false,
   };
 }
 
@@ -975,13 +986,32 @@ gulp.task('jsdoc', function (done) {
 });
 
 gulp.task('lib', ['buildnumber'], function () {
+  // When we create a bundle, webpack is run on the source and it will replace
+  // require with __webpack_require__. When we want to use the real require,
+  // __non_webpack_require__ has to be used.
+  // In this target, we don't create a bundle, so we have to replace the
+  // occurences of __non_webpack_require__ ourselves.
+  function babelPluginReplaceNonWebPackRequire(babel) {
+    return {
+      visitor: {
+        Identifier(path, state) {
+          if (path.node.name === '__non_webpack_require__') {
+            path.replaceWith(babel.types.identifier('require'));
+          }
+        },
+      },
+    };
+  }
   function preprocess(content) {
     var noPreset = /\/\*\s*no-babel-preset\s*\*\//.test(content);
     content = preprocessor2.preprocessPDFJSCode(ctx, content);
     content = babel.transform(content, {
       sourceType: 'module',
       presets: noPreset ? undefined : ['es2015'],
-      plugins: ['transform-es2015-modules-commonjs'],
+      plugins: [
+        'transform-es2015-modules-commonjs',
+        babelPluginReplaceNonWebPackRequire,
+      ],
     }).code;
     var removeCjsSrc =
       /^(var\s+\w+\s*=\s*require\('.*?)(?:\/src)(\/[^']*'\);)$/gm;

src/display/api.js

@@ -12,7 +12,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-/* globals requirejs, __pdfjsdev_webpack__ */
+/* globals requirejs, __non_webpack_require__ */
 
 import {
   createPromiseCapability, deprecated, getVerbosityLevel, globalScope,
@@ -43,21 +43,19 @@ var pdfjsFilePath =
 
 var fakeWorkerFilesLoader = null;
 var useRequireEnsure = false;
-// The if below protected by __pdfjsdev_webpack__ check from webpack parsing.
 if (typeof PDFJSDev !== 'undefined' &&
-    PDFJSDev.test('GENERIC && !SINGLE_FILE') &&
-    typeof __pdfjsdev_webpack__ === 'undefined') {
+    PDFJSDev.test('GENERIC && !SINGLE_FILE')) {
   // For GENERIC build we need add support of different fake file loaders
   // for different  frameworks.
   if (typeof window === 'undefined') {
     // node.js - disable worker and set require.ensure.
     isWorkerDisabled = true;
-    if (typeof require.ensure === 'undefined') {
-      require.ensure = require('node-ensure');
+    if (typeof __non_webpack_require__.ensure === 'undefined') {
+      __non_webpack_require__.ensure = __non_webpack_require__('node-ensure');
     }
     useRequireEnsure = true;
-  } else if (typeof require !== 'undefined' &&
-             typeof require.ensure === 'function') {
+  } else if (typeof __non_webpack_require__ !== 'undefined' &&
+             typeof __non_webpack_require__.ensure === 'function') {
     useRequireEnsure = true;
   }
   if (typeof requirejs !== 'undefined' && requirejs.toUrl) {
@@ -66,12 +64,12 @@ if (typeof PDFJSDev !== 'undefined' &&
   var dynamicLoaderSupported =
     typeof requirejs !== 'undefined' && requirejs.load;
   fakeWorkerFilesLoader = useRequireEnsure ? (function (callback) {
-    require.ensure([], function () {
+    __non_webpack_require__.ensure([], function () {
       var worker;
       if (typeof PDFJSDev !== 'undefined' && PDFJSDev.test('LIB')) {
-        worker = require('../pdf.worker.js');
+        worker = __non_webpack_require__('../pdf.worker.js');
       } else {
-        worker = require('./pdf.worker.js');
+        worker = __non_webpack_require__('./pdf.worker.js');
       }
       callback(worker.WorkerMessageHandler);
     });

src/shared/util.js

@@ -12,13 +12,13 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-/* globals global, process, __pdfjsdev_webpack__ */
 
 import './compatibility';
 import { ReadableStream } from '../../external/streams/streams-lib';
 
 var globalScope =
   (typeof window !== 'undefined' && window.Math === Math) ? window :
+  // eslint-disable-next-line no-undef
   (typeof global !== 'undefined' && global.Math === Math) ? global :
   (typeof self !== 'undefined' && self.Math === Math) ? self : this;
 
@@ -1092,11 +1092,8 @@ function isSpace(ch) {
 }
 
 function isNodeJS() {
-  // The if below protected by __pdfjsdev_webpack__ check from webpack parsing.
-  if (typeof __pdfjsdev_webpack__ === 'undefined') {
-    return typeof process === 'object' && process + '' === '[object process]';
-  }
-  return false;
+  // eslint-disable-next-line no-undef
+  return typeof process === 'object' && process + '' === '[object process]';
 }
 
 /**

web/pdfjs.js

@@ -12,19 +12,16 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-/* globals module, __pdfjsdev_webpack__ */
+/* globals module, __non_webpack_require__ */
 
 'use strict';
 
 var pdfjsLib;
-// The if below protected by __pdfjsdev_webpack__ check from webpack parsing.
-if (typeof __pdfjsdev_webpack__ === 'undefined') {
-  if (typeof window !== 'undefined' && window['pdfjs-dist/build/pdf']) {
-    pdfjsLib = window['pdfjs-dist/build/pdf'];
-  } else if (typeof require === 'function') {
-    pdfjsLib = require('../build/pdf.js');
-  } else {
-    throw new Error('Neither `require` nor `window` found');
-  }
+if (typeof window !== 'undefined' && window['pdfjs-dist/build/pdf']) {
+  pdfjsLib = window['pdfjs-dist/build/pdf'];
+} else if (typeof __non_webpack_require__ === 'function') {
+  pdfjsLib = __non_webpack_require__('../build/pdf.js');
+} else {
+  throw new Error('Neither `require` nor `window` found');
 }
 module.exports = pdfjsLib;