parse configuration and require css-modules-require-hook only once through lifetime of a plugin (perf optimization + bug fix when multiple imports/requires are in one file with advanced options), closes michalkvasnicak#7

Author: michalkvasnicak

src/index.js

@@ -24,9 +24,27 @@ export default function transformCssModules({ types: t }) {
         return resolve(dir);
     }
 
+    /**
+     *
+     * @param {String} filepath     javascript file path
+     * @param {String} cssFile      requireed css file path
+     * @returns {Array} array of class names
+     */
+    function requireCssFile(filepath, cssFile) {
+        const from = resolveModulePath(filepath);
+        return require(resolve(from, cssFile));
+    }
+
+    // is css modules require hook initialized?
+    let initialized = false;
+
     return {
         visitor: {
-            CallExpression(path, { file, opts }) {
+            Program(path, { opts }) {
+                if (initialized) {
+                    return;
+                }
+
                 const currentConfig = { ...defaultOptions, ...opts };
 
                 // check if there are simple requires and if they are functions
@@ -105,6 +123,10 @@ export default function transformCssModules({ types: t }) {
 
                 require('css-modules-require-hook')(currentConfig);
 
+                initialized = true;
+            },
+
+            CallExpression(path, { file }) {
                 const { callee: { name: calleeName }, arguments: args } = path.node;
 
                 if (calleeName !== 'require' || !args.length || !t.isStringLiteral(args[0])) {
@@ -121,8 +143,7 @@ export default function transformCssModules({ types: t }) {
                         );
                     }
 
-                    const from = resolveModulePath(file.opts.filename);
-                    const tokens = require(resolve(from, cssPath));
+                    const tokens = requireCssFile(file.opts.filename, args[0].value);
 
                     /* eslint-disable new-cap */
                     path.replaceWith(t.ObjectExpression(

test/index.spec.js

@@ -1,4 +1,3 @@
-const babel = require('babel-core');
 import { expect } from 'chai';
 import { resolve, join } from 'path';
 import { readFileSync } from 'fs';
@@ -7,6 +6,10 @@ import gulpBabel from 'gulp-babel';
 
 describe('babel-plugin-css-modules-transform', () => {
     function transform(path, configuration = {}) {
+        // remove css modules transform plugin (simulates clean processes)
+        delete require.cache['/Users/Michal/Work/babel-plugin-css-modules-transform/src/index.js'];
+        const babel = require('babel-core');
+
         return babel.transformFileSync(resolve(__dirname, path), {
             plugins: [
                 'transform-strict-mode',
@@ -16,7 +19,7 @@ describe('babel-plugin-css-modules-transform', () => {
                 'transform-object-rest-spread',
                 'transform-es2015-spread',
                 'transform-export-extensions',
-                ['../src/index.js', configuration]
+                ['../../src/index.js', configuration]
             ]
         });
     }
@@ -114,7 +117,7 @@ describe('babel-plugin-css-modules-transform', () => {
                 'transform-object-rest-spread',
                 'transform-es2015-spread',
                 'transform-export-extensions',
-                ['../src/index.js', {}]
+                ['../../src/index.js', {}]
             ]
         });