Better Listr usage and speed improvements

lib/migrate.js

@@ -1,39 +1,55 @@
 const fs = require('fs');
-const diff = require('diff');
 const chalk = require('chalk');
-const jscodeshift = require('jscodeshift');
-const transformations = require('./transformations').transformations;
+const diff = require('diff');
 const inquirer = require('inquirer');
+const PLazy = require('p-lazy');
 const Listr = require('listr');
 
-const migrateTasks = function(ast) {
-	return Object.keys(transformations).map(key => {
-		const transform = transformations[key];
-		return {
-			title: key,
-			task: () => transform(ast)
-		};
-	});
-};
-
-module.exports = function tranformFile(currentConfigPath, outputConfigPath, options) {
+module.exports = function transformFile(currentConfigPath, outputConfigPath, options) {
 	const recastOptions = Object.assign({
 		quote: 'single'
 	}, options);
-	let currentConfig = fs.readFileSync(currentConfigPath, 'utf8');
-	const ast = jscodeshift(currentConfig);
 	const tasks = new Listr([
+		{
+			title: 'Reading webpack config',
+			task: (ctx) => new PLazy((resolve, reject) => {
+				fs.readFile(currentConfigPath, 'utf8', (err, content) => {
+					if (err) {
+						reject(err);
+					}
+					try {
+						console.time('Reading webpack config');
+						const jscodeshift = require('jscodeshift');
+						ctx.source = content;
+						ctx.ast = jscodeshift(content);
+						resolve();
+						console.timeEnd('Reading webpack config');
+					} catch (err) {
+						reject('Error generating AST', err);
+					}
+				});
+			})
+		},
 		{
 			title: 'Migrating config from v1 to v2',
-			task: () => new Listr(migrateTasks(ast))
+			task: (ctx) => {
+				const transformations = require('./transformations').transformations;
+				return new Listr(Object.keys(transformations).map(key => {
+					const transform = transformations[key];
+					return {
+						title: key,
+						task: () => transform(ctx.ast, ctx.source)
+					};
+				}));
+			}
 		}
 	]);
 
 	tasks.run()
-		.then(() => {
-			const outputConfig = ast.toSource(recastOptions);
-			const diffOutput = diff.diffLines(currentConfig, outputConfig);
-			diffOutput.map(diffLine => {
+		.then((ctx) => {
+			const result = ctx.ast.toSource(recastOptions);
+			const diffOutput = diff.diffLines(ctx.source, result);
+			diffOutput.forEach(diffLine => {
 				if (diffLine.added) {
 					process.stdout.write(chalk.green(`+ ${diffLine.value}`));
 				} else if (diffLine.removed) {
@@ -52,15 +68,16 @@ module.exports = function tranformFile(currentConfigPath, outputConfigPath, opti
 				.then(answers => {
 					if (answers['confirmMigration']) {
 						// TODO validate the config
-						fs.writeFileSync(outputConfigPath, outputConfig, 'utf8');
-						process.stdout.write(chalk.green(`✔︎ New webpack v2 config file is at ${outputConfigPath}`));
+						fs.writeFileSync(outputConfigPath, result, 'utf8');
+						console.log(chalk.green(`✔︎ New webpack v2 config file is at ${outputConfigPath}`));
 					} else {
-						process.stdout.write(chalk.red('✖ Migration aborted'));
+						console.log(chalk.red('✖ Migration aborted'));
 					}
 				});
 		})
 		.catch(err => {
-			console.error(chalk.red('✖ ︎Migration aborted due to some errors'));
+			console.log(chalk.red('✖ ︎Migration aborted due to some errors'));
 			console.error(err);
+			process.exitCode = 1;
 		});
 };

lib/transformations/index.js

@@ -1,5 +1,6 @@
 const jscodeshift = require('jscodeshift');
 const pEachSeries = require('p-each-series');
+const PLazy = require('p-lazy');
 
 const loadersTransform = require('./loaders/loaders');
 const resolveTransform = require('./resolve/resolve');
@@ -22,15 +23,15 @@ const transformsObject = {
 };
 
 const transformations = Object.keys(transformsObject).reduce((res, key) => {
-	res[key] = (ast) => transformSingleAST(ast, transformsObject[key]);
+	res[key] = (ast, source) => transformSingleAST(ast, source, transformsObject[key]);
 	return res;
 }, {});
 
-function transformSingleAST(ast, transformFunction) {
-	return new Promise((resolve, reject) => {
+function transformSingleAST(ast, source, transformFunction) {
+	return new PLazy((resolve, reject) => {
 		setTimeout(() => {
 			try {
-				resolve(transformFunction(jscodeshift, ast));
+				resolve(transformFunction(jscodeshift, ast, source));
 			} catch (err) {
 				reject(err);
 			}

package.json

@@ -42,6 +42,7 @@
     "loader-utils": "^0.2.16",
     "lodash": "^4.17.4",
     "p-each-series": "^1.0.0",
+    "p-lazy": "^1.0.0",
     "recast": "git://github.com/kalcifer/recast.git#bug/allowbreak",
     "rx": "^4.1.0",
     "supports-color": "^3.1.2",