Refactor Exports, Add UTF-8 Tests

package.json

@@ -45,7 +45,6 @@
     "@types/acorn": "4.0.5",
     "@types/estree": "0.0.41",
     "@types/node": "12.12.24",
-    "@types/temp-write": "3.3.0",
     "@types/uuid": "3.4.6",
     "ava": "2.4.0",
     "builtins": "3.0.0",
@@ -65,6 +64,10 @@
     "*.ts": [
       "prettier --config .prettierrc --write",
       "git add"
+    ],
+    "*.test.js": [
+      "prettier --config .prettierrc --write",
+      "git add"
     ]
   },
   "husky": {

src/compiler.ts

@@ -21,6 +21,7 @@ const {
 } = require('google-closure-compiler/lib/utils.js');
 import { Transform } from './types';
 import { postCompilation } from './transforms';
+import { RenderedChunk } from 'rollup';
 
 enum Platform {
   NATIVE = 'native',
@@ -71,6 +72,7 @@ function orderPlatforms(platformPreference: Platform | string): Array<Platform>
  */
 export default function(
   compileOptions: CompileOptions,
+  chunk: RenderedChunk,
   transforms: Array<Transform>,
 ): Promise<string> {
   return new Promise((resolve: (stdOut: string) => void, reject: (error: any) => void) => {
@@ -95,7 +97,7 @@ export default function(
       } else if (exitCode !== 0) {
         reject(new Error(`Google Closure Compiler exit ${exitCode}: ${stdErr}`));
       } else {
-        resolve(await postCompilation(code, transforms));
+        resolve(await postCompilation(code, chunk, transforms));
       }
     });
   });

src/debug.ts

@@ -18,24 +18,30 @@ import { writeTempFile } from './temp-file';
 
 const DEBUG_ENABLED = false;
 
-/* c8 ignore next 12 */
-export const logSource = async (preamble: string, source: string, code?: string): Promise<void> => {
+/* c8 ignore next 16 */
+export async function logTransformChain(
+  file: string,
+  stage: string,
+  messages: Array<[string, string]>,
+): Promise<void> {
   if (DEBUG_ENABLED) {
-    const sourceLocation: string = await writeTempFile(source);
-    const codeLocation: string = code ? await writeTempFile(code) : '';
-
-    console.log(preamble);
-    console.log(sourceLocation);
-    if (code) {
-      console.log(codeLocation);
+    let output: string = `\n${file} - ${stage}`;
+    for (const [message, source] of messages) {
+      output += `\n${message.substr(0, 15).padEnd(18, '.')} - file://${await writeTempFile(
+        source,
+        '.js',
+      )}`;
     }
+    console.log(output);
   }
-};
+}
 
-/* c8 ignore next 6 */
-export const log = (preamble: string, message: string | object): void | null => {
+/* c8 ignore next 8 */
+export const log = (preamble: string | undefined, message: string | object): void | null => {
   if (DEBUG_ENABLED) {
-    console.log(preamble);
+    if (preamble) {
+      console.log(preamble);
+    }
     console.log(message);
   }
 };

src/index.ts

@@ -42,8 +42,9 @@ const renderChunk = async (
   requestedCompileOptions: CompileOptions = {},
   sourceCode: string,
   outputOptions: OutputOptions,
+  chunk: RenderedChunk,
 ): Promise<{ code: string; map: SourceMapInput } | void> => {
-  const code = await preCompilation(sourceCode, outputOptions, transforms);
+  const code = await preCompilation(sourceCode, outputOptions, chunk, transforms);
   const [compileOptions, mapFile] = await options(
     requestedCompileOptions,
     outputOptions,
@@ -53,7 +54,7 @@ const renderChunk = async (
 
   try {
     return {
-      code: await compiler(compileOptions, transforms),
+      code: await compiler(compileOptions, chunk, transforms),
       map: JSON.parse(await fsPromises.readFile(mapFile, 'utf8')),
     };
   } catch (error) {
@@ -82,7 +83,13 @@ export default function closureCompiler(requestedCompileOptions: CompileOptions
     },
     renderChunk: async (code: string, chunk: RenderedChunk, outputOptions: OutputOptions) => {
       const transforms = createTransforms(context, inputOptions);
-      const output = await renderChunk(transforms, requestedCompileOptions, code, outputOptions);
+      const output = await renderChunk(
+        transforms,
+        requestedCompileOptions,
+        code,
+        outputOptions,
+        chunk,
+      );
       return output || null;
     },
   };

src/options.ts

@@ -15,7 +15,7 @@
  */
 
 import { Transform } from './types';
-import { ModuleFormat, OutputOptions } from 'rollup';
+import { OutputOptions } from 'rollup';
 import { CompileOptions } from 'google-closure-compiler';
 import { writeTempFile } from './temp-file';
 import { log } from './debug';
@@ -27,10 +27,11 @@ export const ERROR_WARNINGS_ENABLED_LANGUAGE_OUT_INVALID =
 
 /**
  * Checks if output format is ESM
- * @param format
+ * @param outputOptions
  * @return boolean
  */
-export const isESMFormat = (format?: ModuleFormat): boolean => format === 'esm' || format === 'es';
+export const isESMFormat = ({ format }: OutputOptions): boolean =>
+  format === 'esm' || format === 'es';
 
 /**
  * Throw Errors if compile options will result in unexpected behaviour.
@@ -69,13 +70,14 @@ export const defaults = async (
   for (const transform of transformers || []) {
     const extern = transform.extern(options);
     if (extern !== null) {
-      transformerExterns.push(await writeTempFile(extern));
+      const writtenExtern = await writeTempFile(extern);
+      transformerExterns.push(writtenExtern);
     }
   }
 
   return {
     language_out: 'NO_TRANSPILE',
-    assume_function_wrapper: isESMFormat(options.format),
+    assume_function_wrapper: isESMFormat(options),
     warning_level: 'QUIET',
     module_resolution: 'NODE',
     externs: transformerExterns.concat(providedExterns),

src/parsing/export-details.ts

@@ -14,7 +14,14 @@
  * limitations under the License.
  */
 
-import { ExportNamedDeclaration, ExportDefaultDeclaration } from 'estree';
+import {
+  ExportNamedDeclaration,
+  ExportDefaultDeclaration,
+  Node,
+  ExpressionStatement,
+  MemberExpression,
+  Expression,
+} from 'estree';
 import { ExportDetails, Range, ExportClosureMapping } from '../types';
 
 export function NamedDeclaration(declaration: ExportNamedDeclaration): Array<ExportDetails> {
@@ -26,7 +33,6 @@ export function NamedDeclaration(declaration: ExportNamedDeclaration): Array<Exp
     exportDetails.push({
       local: specifier.local.name,
       exported: specifier.exported.name,
-      closureName: specifier.exported.name,
       type: ExportClosureMapping.NAMED_CONSTANT,
       range: declaration.range as Range,
       source,
@@ -46,7 +52,6 @@ export function DefaultDeclaration(
       {
         local: declaration.name,
         exported: declaration.name,
-        closureName: declaration.name,
         type: ExportClosureMapping.NAMED_DEFAULT_FUNCTION,
         range: defaultDeclaration.range as Range,
         source: null,
@@ -56,3 +61,26 @@ export function DefaultDeclaration(
 
   return [];
 }
+
+export function NodeIsPreservedExport(node: Node): node is ExpressionStatement {
+  return (
+    node.type === 'ExpressionStatement' &&
+    node.expression.type === 'AssignmentExpression' &&
+    node.expression.left.type === 'MemberExpression' &&
+    node.expression.left.object.type === 'Identifier' &&
+    node.expression.left.object.name === 'window'
+  );
+}
+
+export function PreservedExportName(node: MemberExpression): string | null {
+  const { property }: { property: Expression } = node;
+
+  if (property.type === 'Identifier') {
+    return property.name;
+  }
+  if (property.type === 'Literal' && typeof property.value === 'string') {
+    return property.value;
+  }
+
+  return null;
+}

src/parsing/import-specifiers.ts

@@ -17,7 +17,7 @@
 import { IMPORT_SPECIFIER, IMPORT_NAMESPACE_SPECIFIER, IMPORT_DEFAULT_SPECIFIER } from '../types';
 import { ImportSpecifier, ImportDefaultSpecifier, ImportNamespaceSpecifier } from 'estree';
 
-export interface Specifiers {
+interface Specifiers {
   default: string | null;
   specific: Array<string>;
   local: Array<string>;

src/parsing/literal-name.ts

@@ -17,6 +17,5 @@
 import { Literal, SimpleLiteral } from 'estree';
 
 export function literalName(literal: Literal): string {
-  const literalValue = (literal as SimpleLiteral).value;
-  return typeof literalValue === 'string' ? literalValue : '';
+  return (literal as SimpleLiteral).value as string;
 }

src/parsing/preserve-default-export.ts

@@ -0,0 +1,39 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * 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.
+ */
+
+import { ExpressionStatement, AssignmentExpression, MemberExpression } from 'estree';
+import { ExportDetails, Range } from '../types';
+import MagicString from 'magic-string';
+
+export function PreserveDefault(
+  code: string,
+  source: MagicString,
+  ancestor: ExpressionStatement,
+  exportDetails: ExportDetails,
+  exportInline: boolean,
+): boolean {
+  const assignmentExpression = ancestor.expression as AssignmentExpression;
+  const memberExpression = assignmentExpression.left as MemberExpression;
+  const [memberExpressionStart, memberExpressionEnd]: Range = memberExpression.range as Range;
+
+  source.overwrite(
+    memberExpressionStart,
+    memberExpressionEnd + assignmentExpression.operator.length,
+    'export default ',
+  );
+
+  return false;
+}

src/parsing/preserve-named-constant-export.ts

@@ -0,0 +1,111 @@
+/**
+ * Copyright 2020 The AMP HTML Authors. All Rights Reserved.
+ *
+ * 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.
+ */
+
+import {
+  ExpressionStatement,
+  AssignmentExpression,
+  FunctionExpression,
+  MemberExpression,
+} from 'estree';
+import { ExportDetails, Range } from '../types';
+import MagicString from 'magic-string';
+
+function PreserveFunction(
+  code: string,
+  source: MagicString,
+  ancestor: ExpressionStatement,
+  exportDetails: ExportDetails,
+  exportInline: boolean,
+): boolean {
+  // Function Expressions can be inlined instead of preserved as variable references.
+  // window['foo'] = function(){}; => export function foo(){} / function foo(){}
+  const assignmentExpression = ancestor.expression as AssignmentExpression;
+  const memberExpression = assignmentExpression.left as MemberExpression;
+  const functionExpression = assignmentExpression.right as FunctionExpression;
+  const [memberExpressionObjectStart] = memberExpression.object.range as Range;
+  const functionName = exportInline ? exportDetails.exported : exportDetails.local;
+
+  if (functionExpression.params.length > 0) {
+    const [paramsStart] = functionExpression.params[0].range as Range;
+    // FunctionExpression has parameters.
+    source.overwrite(
+      memberExpressionObjectStart,
+      paramsStart,
+      `${exportInline ? 'export ' : ''}function ${functionName}(`,
+    );
+  } else {
+    const [bodyStart] = functionExpression.body.range as Range;
+    source.overwrite(
+      memberExpressionObjectStart,
+      bodyStart,
+      `${exportInline ? 'export ' : ''}function ${functionName}()`,
+    );
+  }
+
+  return !exportInline;
+}
+
+function PreserveIdentifier(
+  code: string,
+  source: MagicString,
+  ancestor: ExpressionStatement,
+  exportDetails: ExportDetails,
+  exportInline: boolean,
+): boolean {
+  const assignmentExpression = ancestor.expression as AssignmentExpression;
+  const left = assignmentExpression.left;
+  const right = assignmentExpression.right;
+  const [ancestorStart, ancestorEnd]: Range = ancestor.range as Range;
+  const [rightStart, rightEnd]: Range = right.range as Range;
+
+  if (exportInline) {
+    source.overwrite(
+      ancestorStart,
+      ancestorEnd,
+      `export var ${exportDetails.exported}=${code.substring(rightStart, rightEnd)};`,
+    );
+  } else if (exportDetails.source === null && 'name' in right) {
+    // This is a locally defined identifier with a name we can use.
+    exportDetails.local = right.name;
+    source.remove((left.range as Range)[0], rightEnd + 1);
+    return true;
+  } else {
+    // exportDetails.local =
+    source.overwrite(
+      ancestorStart,
+      ancestorEnd,
+      `var ${exportDetails.local}=${code.substring(rightStart, rightEnd)};`,
+    );
+  }
+
+  return !exportInline;
+}
+
+export function PreserveNamedConstant(
+  code: string,
+  source: MagicString,
+  ancestor: ExpressionStatement,
+  exportDetails: ExportDetails,
+  exportInline: boolean,
+): boolean {
+  const assignmentExpression = ancestor.expression as AssignmentExpression;
+  switch (assignmentExpression.right.type) {
+    case 'FunctionExpression':
+      return PreserveFunction(code, source, ancestor, exportDetails, exportInline);
+    default:
+      return PreserveIdentifier(code, source, ancestor, exportDetails, exportInline);
+  }
+}