Refactor loader's code

src/CssDependency.js

@@ -0,0 +1,22 @@
+import webpack from 'webpack';
+
+export default class CssDependency extends webpack.Dependency {
+  constructor(
+    { identifier, content, media, sourceMap },
+    context,
+    identifierIndex
+  ) {
+    super();
+
+    this.identifier = identifier;
+    this.identifierIndex = identifierIndex;
+    this.content = content;
+    this.media = media;
+    this.sourceMap = sourceMap;
+    this.context = context;
+  }
+
+  getResourceIdentifier() {
+    return `css-module-${this.identifier}-${this.identifierIndex}`;
+  }
+}

src/index.js

@@ -3,6 +3,8 @@
 import webpack from 'webpack';
 import sources from 'webpack-sources';
 
+import CssDependency from './CssDependency';
+
 const { ConcatSource, SourceMapSource, OriginalSource } = sources;
 const {
   Template,
@@ -19,27 +21,6 @@ const REGEXP_NAME = /\[name\]/i;
 const REGEXP_PLACEHOLDERS = /\[(name|id|chunkhash)\]/g;
 const DEFAULT_FILENAME = '[name].css';
 
-class CssDependency extends webpack.Dependency {
-  constructor(
-    { identifier, content, media, sourceMap },
-    context,
-    identifierIndex
-  ) {
-    super();
-
-    this.identifier = identifier;
-    this.identifierIndex = identifierIndex;
-    this.content = content;
-    this.media = media;
-    this.sourceMap = sourceMap;
-    this.context = context;
-  }
-
-  getResourceIdentifier() {
-    return `css-module-${this.identifier}-${this.identifierIndex}`;
-  }
-}
-
 class CssDependencyTemplate {
   apply() {}
 }
@@ -148,30 +129,6 @@ class MiniCssExtractPlugin {
 
   apply(compiler) {
     compiler.hooks.thisCompilation.tap(pluginName, (compilation) => {
-      compilation.hooks.normalModuleLoader.tap(pluginName, (lc, m) => {
-        const loaderContext = lc;
-        const module = m;
-
-        loaderContext[MODULE_TYPE] = (content) => {
-          if (!Array.isArray(content) && content != null) {
-            throw new Error(
-              `Exported value was not extracted as an array: ${JSON.stringify(
-                content
-              )}`
-            );
-          }
-
-          const identifierCountMap = new Map();
-
-          for (const line of content) {
-            const count = identifierCountMap.get(line.identifier) || 0;
-
-            module.addDependency(new CssDependency(line, m.context, count));
-            identifierCountMap.set(line.identifier, count + 1);
-          }
-        };
-      });
-
       compilation.dependencyFactories.set(
         CssDependency,
         new CssModuleFactory()

src/loader.js

@@ -10,9 +10,10 @@ import SingleEntryPlugin from 'webpack/lib/SingleEntryPlugin';
 import LimitChunkCountPlugin from 'webpack/lib/optimize/LimitChunkCountPlugin';
 import validateOptions from 'schema-utils';
 
+import CssDependency from './CssDependency';
+
 import schema from './options.json';
 
-const MODULE_TYPE = 'css/mini-extract';
 const pluginName = 'mini-css-extract-plugin';
 
 function hotLoader(content, context) {
@@ -36,25 +37,25 @@ function hotLoader(content, context) {
   `;
 }
 
-const exec = (loaderContext, code, filename) => {
+function evalModuleCode(loaderContext, code, filename) {
   const module = new NativeModule(filename, loaderContext);
 
   module.paths = NativeModule._nodeModulePaths(loaderContext.context); // eslint-disable-line no-underscore-dangle
   module.filename = filename;
   module._compile(code, filename); // eslint-disable-line no-underscore-dangle
 
   return module.exports;
-};
+}
 
-const findModuleById = (modules, id) => {
+function findModuleById(modules, id) {
   for (const module of modules) {
     if (module.id === id) {
       return module;
     }
   }
 
   return null;
-};
+}
 
 export function pitch(request) {
   const options = loaderUtils.getOptions(this) || {};
@@ -91,8 +92,6 @@ export function pitch(request) {
   );
   new LimitChunkCountPlugin({ maxChunks: 1 }).apply(childCompiler);
 
-  // We set loaderContext[MODULE_TYPE] = false to indicate we already in
-  // a child compiler so we don't spawn another child compilers from there.
   childCompiler.hooks.thisCompilation.tap(
     `${pluginName} loader`,
     (compilation) => {
@@ -101,7 +100,6 @@ export function pitch(request) {
         (loaderContext, module) => {
           // eslint-disable-next-line no-param-reassign
           loaderContext.emitFile = this.emitFile;
-          loaderContext[MODULE_TYPE] = false; // eslint-disable-line no-param-reassign
 
           if (module.request === request) {
             // eslint-disable-next-line no-param-reassign
@@ -136,6 +134,27 @@ export function pitch(request) {
   const callback = this.async();
 
   childCompiler.runAsChild((err, entries, compilation) => {
+    const addDependencies = (content) => {
+      if (!Array.isArray(content) && content != null) {
+        throw new Error(
+          `Exported value was not extracted as an array: ${JSON.stringify(
+            content
+          )}`
+        );
+      }
+
+      const identifierCountMap = new Map();
+
+      for (const line of content) {
+        const count = identifierCountMap.get(line.identifier) || 0;
+
+        this._module.addDependency(
+          new CssDependency(line, module.context, count)
+        );
+        identifierCountMap.set(line.identifier, count + 1);
+      }
+    };
+
     if (err) {
       return callback(err);
     }
@@ -156,27 +175,27 @@ export function pitch(request) {
       return callback(new Error("Didn't get a result from child compiler"));
     }
 
-    let text;
     let locals;
 
     try {
-      text = exec(this, source, request);
-      locals = text && text.locals;
-      if (!Array.isArray(text)) {
-        text = [[null, text]];
+      let dependencies;
+      const exports = evalModuleCode(this, source, request);
+      locals = exports && exports.locals;
+      if (!Array.isArray(exports)) {
+        dependencies = [[null, exports]];
       } else {
-        text = text.map((line) => {
-          const module = findModuleById(compilation.modules, line[0]);
+        dependencies = exports.map(([id, content, media, sourceMap]) => {
+          const module = findModuleById(compilation.modules, id);
 
           return {
             identifier: module.identifier(),
-            content: line[1],
-            media: line[2],
-            sourceMap: line[3],
+            content,
+            media,
+            sourceMap,
           };
         });
       }
-      this[MODULE_TYPE](text);
+      addDependencies(dependencies);
     } catch (e) {
       return callback(e);
     }