feat(*): learn loader to pick-up precompiled files if any

Author: Stanislav Panferov

src/deps.ts

@@ -1,6 +1,7 @@
 import * as _ from 'lodash';
 import * as util from 'util';
 import * as path from 'path';
+import * as fs from 'fs';
 import * as Promise from 'bluebird';
 
 import { State } from './host';
@@ -230,10 +231,12 @@ export interface IDependencyGraphItem {
 export class DependencyManager {
     dependencies: {[fileName: string]: string[]};
     knownTypeDeclarations: FileSet;
+    compiledModules: {[fileName: string]: string[]};
 
     constructor(dependencies: {[fileName: string]: string[]} = {}, knownTypeDeclarations: FileSet = {}) {
         this.dependencies = dependencies;
         this.knownTypeDeclarations = knownTypeDeclarations;
+        this.compiledModules = {};
     }
 
     clone(): DependencyManager {
@@ -251,10 +254,26 @@ export class DependencyManager {
         this.dependencies[fileName].push(depFileName);
     }
 
+    addCompiledModule(fileName: string, depFileName: string): void {
+        if (!this.compiledModules.hasOwnProperty(fileName)) {
+            this.clearCompiledModules(fileName);
+        }
+
+        let store = this.compiledModules[fileName];
+
+        if (store.indexOf(depFileName) === -1) {
+            store.push(depFileName);
+        }
+    }
+
     clearDependencies(fileName: string): void {
         this.dependencies[fileName] = []
     }
 
+    clearCompiledModules(fileName: string): void {
+        this.compiledModules[fileName] = []
+    }
+
     getDependencies(fileName: string): string[] {
         if (!this.dependencies.hasOwnProperty(fileName)) {
             this.clearDependencies(fileName);
@@ -317,6 +336,16 @@ export class DependencyManager {
         return result.buf += '\n\n';
     }
 
+    applyCompiledFiles(fileName: string, deps: IDependency) {
+        if (!this.compiledModules.hasOwnProperty(fileName)) {
+            this.clearCompiledModules(fileName);
+        }
+
+        this.compiledModules[fileName].forEach((mod) => {
+            deps.add(mod)
+        })
+    }
+
     applyChain(fileName: string, deps: IDependency) {
         if (!this.dependencies.hasOwnProperty(fileName)) {
             this.clearDependencies(fileName);
@@ -354,6 +383,36 @@ export class ValidFilesManager {
     }
 }
 
+export interface CompiledModule {
+    fileName: string,
+    text: string,
+    map?: string,
+    mapName?: string
+}
+
+export function findCompiledModule(fileName: string): CompiledModule {
+    let baseFileName = fileName.replace(/(\.ts|\.tsx)$/, '');
+    let compiledFileName = `${baseFileName}.js`
+
+    if (fs.existsSync(compiledFileName)) {
+        let mapFileName = `${baseFileName}.js.map`;
+        let isMapExists = fs.existsSync(mapFileName);
+        let result = {
+            fileName: compiledFileName,
+            text: fs.readFileSync(compiledFileName).toString(),
+            mapName: isMapExists
+                ? mapFileName
+                : null,
+            map: isMapExists
+                ? fs.readFileSync(mapFileName).toString()
+                : null
+        }
+        return result;
+    } else {
+        return null;
+    }
+}
+
 /**
  * Emit compilation result for a specified fileName.
  */

src/host.ts

@@ -38,6 +38,7 @@ export interface ICompilerOptions extends ts.CompilerOptions {
     externals?: any;
     doTypeCheck?: boolean;
     forkChecker?: boolean;
+    useBabel?: boolean;
 }
 
 export interface IOutputFile extends ts.OutputFile {

src/index.ts

@@ -9,7 +9,7 @@ import * as childProcess from 'child_process';
 import * as colors from 'colors';
 
 import { ICompilerOptions, TypeScriptCompilationError, State, ICompilerInfo } from './host';
-import { IResolver, ResolutionError } from './deps';
+import { IResolver, ResolutionError, findCompiledModule } from './deps';
 import * as helpers from './helpers';
 import { loadLib } from './helpers';
 
@@ -39,6 +39,7 @@ interface IWebPack {
 interface ICompilerInstance {
     tsFlow: Promise<any>;
     tsState: State;
+    babelImpl?: any;
     compiledFiles: {[key:string]: boolean};
     options: ICompilerOptions;
     externalsInvoked: boolean;
@@ -106,6 +107,10 @@ const COMPILER_ERROR = colors.red(`\n\nTypescript compiler cannot be found, plea
     npm install --save-dev typescript
 `);
 
+const BABEL_ERROR = colors.red(`\n\nBabel compiler cannot be found, please add it to your package.json file:
+    npm install --save-dev babel
+`);
+
 /**
  * Creates compiler instance
  */
@@ -223,6 +228,16 @@ function ensureInstance(webpack: IWebPack, options: ICompilerOptions, instanceNa
         options.target = helpers.parseOptionTarget(<any>options.target, tsImpl);
     }
 
+    let babelImpl: any;
+    if (options.useBabel) {
+        try {
+            babelImpl = require(path.join(process.cwd(), 'node_modules', 'babel'));
+        } catch (e) {
+            console.error(BABEL_ERROR);
+            process.exit(1);
+        }
+    }
+
     let tsState = new State(options, webpack._compiler.inputFileSystem, compilerInfo);
     let compiler = (<any>webpack._compiler);
 
@@ -301,6 +316,7 @@ function ensureInstance(webpack: IWebPack, options: ICompilerOptions, instanceNa
     return getInstanceStore(webpack._compiler)[instanceName] = {
         tsFlow,
         tsState,
+        babelImpl,
         compiledFiles: {},
         options,
         externalsInvoked: false,
@@ -330,6 +346,7 @@ function compiler(webpack: IWebPack, text: string): void {
     let fileName = webpack.resourcePath;
 
     let resolver = createResolver(webpack._compiler, webpack.resolve);
+    let isDepsApplied = false;
 
     let depsInjector = {
         add: (depFileName) => {webpack.addDependency(depFileName)},
@@ -339,6 +356,7 @@ function compiler(webpack: IWebPack, text: string): void {
     let applyDeps = _.once(() => {
         depsInjector.clear();
         depsInjector.add(fileName);
+        state.fileAnalyzer.dependencies.applyCompiledFiles(fileName, depsInjector);
         if (state.options.reEmitDependentFiles) {
             state.fileAnalyzer.dependencies.applyChain(fileName, depsInjector);
         }
@@ -370,31 +388,59 @@ function compiler(webpack: IWebPack, text: string): void {
             });
         })
         .then(() => {
-            return state.emit(fileName)
-        })
-        .then(output => {
-            let result = helpers.findResultFor(output, fileName);
+            let resultText;
+            let resultSourceMap;
+
+            let compiledModule = findCompiledModule(fileName);
+            if (compiledModule) {
+                state.fileAnalyzer.dependencies.addCompiledModule(fileName, compiledModule.fileName);
+                resultText = compiledModule.text;
+                resultSourceMap = JSON.parse(compiledModule.map);
+            } else {
+                let output = state.emit(fileName);
+                let result = helpers.findResultFor(output, fileName);
 
-            if (result.text === undefined) {
-                throw new Error('no output found for ' + fileName);
+                if (result.text === undefined) {
+                    throw new Error('No output found for ' + fileName);
+                }
+
+                resultText = result.text;
+                resultSourceMap = JSON.parse(result.sourceMap);
+                resultSourceMap.sources = [ fileName ];
+                resultSourceMap.file = fileName;
+                resultSourceMap.sourcesContent = [ text ];
+
+                if (instance.options.useBabel) {
+                    let defaultOptions = {
+                        inputSourceMap: resultSourceMap,
+                        filename: fileName,
+                        sourceMap: true
+                    }
+
+                    let babelResult = instance.babelImpl.transform(resultText, defaultOptions);
+                    resultText = babelResult.code;
+                    resultSourceMap = babelResult.map;
+                }
             }
 
-            let sourceMap = JSON.parse(result.sourceMap);
-            sourceMap.sources = [ fileName ];
-            sourceMap.file = fileName;
-            sourceMap.sourcesContent = [ text ];
+            resultSourceMap.sources = [ fileName ];
+            resultSourceMap.file = fileName;
+            resultSourceMap.sourcesContent = [ text ];
 
             applyDeps();
+            isDepsApplied = true;
 
             try {
-                callback(null, result.text, sourceMap);
+                callback(null, resultText, resultSourceMap)
             } catch (e) {
                 console.error('Error in bail mode:', e);
                 process.exit(1);
             }
         })
         .finally(() => {
-            applyDeps();
+            if (!isDepsApplied) {
+                applyDeps();
+            }
         })
         .catch(ResolutionError, err => {
             callback(err, helpers.codegenErrorReport([err]));

webpack.backend.config.js

@@ -45,11 +45,6 @@ module.exports = {
                 test: /\.ts$/,
                 loader: "awesome-typescript?rewriteImports=alfa-react-ui&externals=" + typeLib
             },
-            {
-                test: /\.js$/,
-                exclude: /(node_modules|bower_components)/,
-                loader: 'babel-loader'
-            },
             {
                 test: /\.json$/,
                 loader: "json-loader"