Move webpackImporter to dedicated module

lib/loader.js

@@ -7,10 +7,8 @@ const os = require("os");
 const async = require("async");
 const assign = require("object-assign");
 const formatSassError = require("./formatSassError");
-const importsToResolve = require("./importsToResolve");
 const proxyCustomImporters = require("./proxyCustomImporters");
-
-const matchCss = /\.css$/;
+const webpackImporter = require("./webpackImporter");
 
 // This queue makes sure node-sass leaves one thread available for executing
 // fs tasks when running the custom importer code.
@@ -31,73 +29,6 @@ function sassLoader(content) {
     const self = this;
     const resourcePath = this.resourcePath;
 
-    /**
-     * Returns an importer that uses webpack's resolving algorithm.
-     *
-     * It's important that the returned function has the correct number of arguments
-     * (based on whether the call is sync or async) because otherwise node-sass doesn't exit.
-     *
-     * @returns {Function}
-     */
-    function getWebpackImporter() {
-        return function asyncWebpackImporter(url, fileContext, done) {
-            // node-sass returns UNIX-style paths
-            fileContext = path.normalize(fileContext);
-            const request = utils.urlToRequest(url, sassOptions.root);
-            const dirContext = fileToDirContext(fileContext);
-
-            resolve(dirContext, url, importsToResolve(request), done);
-        };
-    }
-
-    /**
-     * Tries to resolve the first url of importsToResolve. If that resolve fails, the next url is tried.
-     * If all imports fail, the import is passed to libsass which also take includePaths into account.
-     *
-     * @param {string} dirContext
-     * @param {string} originalImport
-     * @param {Array} importsToResolve
-     * @param {Function} done
-     */
-    function resolve(dirContext, originalImport, importsToResolve, done) {
-        const importToResolve = importsToResolve.shift();
-
-        if (!importToResolve) {
-            // No import possibilities left. Let's pass that one back to libsass...
-            done({
-                file: originalImport
-            });
-            return;
-        }
-
-        self.resolve(dirContext, importToResolve, (err, resolvedFilename) => {
-            if (err) {
-                resolve(dirContext, originalImport, importsToResolve, done);
-                return;
-            }
-            // Add the resolvedFilename as dependency. Although we're also using stats.includedFiles, this might come
-            // in handy when an error occurs. In this case, we don't get stats.includedFiles from node-sass.
-            addNormalizedDependency(resolvedFilename);
-            // By removing the CSS file extension, we trigger node-sass to include the CSS file instead of just linking it.
-            resolvedFilename = resolvedFilename.replace(matchCss, "");
-
-            // Use self.loadModule() before calling done() to make imported files available to
-            // other webpack tools like postLoaders etc.?
-
-            done({
-                file: resolvedFilename.replace(matchCss, "")
-            });
-        });
-    }
-
-    function fileToDirContext(fileContext) {
-        // The first file is 'stdin' when we're using the data option
-        if (fileContext === "stdin") {
-            fileContext = resourcePath;
-        }
-        return path.dirname(fileContext);
-    }
-
     // When files have been imported via the includePaths-option, these files need to be
     // introduced to webpack in order to make them watchable.
     function addIncludedFilesToWebpack(includedFiles) {
@@ -159,7 +90,11 @@ function sassLoader(content) {
 
     // Allow passing custom importers to `node-sass`. Accepts `Function` or an array of `Function`s.
     sassOptions.importer = sassOptions.importer ? proxyCustomImporters(sassOptions.importer, resourcePath) : [];
-    sassOptions.importer.push(getWebpackImporter());
+    sassOptions.importer.push(webpackImporter(
+        this.resourcePath,
+        this.resolve.bind(this),
+        addNormalizedDependency
+    ));
 
     // `node-sass` uses `includePaths` to resolve `@import` paths. Append the currently processed file.
     sassOptions.includePaths = sassOptions.includePaths ? [].concat(sassOptions.includePaths) : [];

lib/webpackImporter.js

@@ -0,0 +1,81 @@
+"use strict";
+
+const path = require("path");
+const utils = require("loader-utils");
+const importsToResolve = require("./importsToResolve");
+
+const matchCss = /\.css$/;
+
+/**
+ * Returns an importer that uses webpack's resolving algorithm.
+ *
+ * It's important that the returned function has the correct number of arguments
+ * (based on whether the call is sync or async) because otherwise node-sass doesn't exit.
+ *
+ * @param {string} resourcePath
+ * @param {Function<string, string, Function<Error, string>>} loaderResolve
+ * @param {Function<string>} addNormalizedDependency
+ * @returns {Function<string, string, Function>}
+ */
+function webpackImporter(resourcePath, loaderResolve, addNormalizedDependency) {
+    /**
+     * Tries to resolve the first url of importsToResolve. If that resolve fails, the next url is tried.
+     * If all imports fail, the import is passed to libsass which also take includePaths into account.
+     *
+     * @param {string} dirContext
+     * @param {string} originalImport
+     * @param {Array} importsToResolve
+     * @param {Function} done
+     */
+    function resolve(dirContext, originalImport, importsToResolve, done) {
+        const importToResolve = importsToResolve.shift();
+
+        if (!importToResolve) {
+            // No import possibilities left. Let's pass that one back to libsass...
+            done({
+                file: originalImport
+            });
+            return;
+        }
+
+        loaderResolve(dirContext, importToResolve, (err, resolvedFilename) => {
+            if (err) {
+                resolve(dirContext, originalImport, importsToResolve, done);
+                return;
+            }
+            // Add the resolvedFilename as dependency. Although we're also using stats.includedFiles, this might come
+            // in handy when an error occurs. In this case, we don't get stats.includedFiles from node-sass.
+            addNormalizedDependency(resolvedFilename);
+            // By removing the CSS file extension, we trigger node-sass to include the CSS file instead of just linking it.
+            resolvedFilename = resolvedFilename.replace(matchCss, "");
+
+            // Use self.loadModule() before calling done() to make imported files available to
+            // other webpack tools like postLoaders etc.?
+
+            done({
+                file: resolvedFilename.replace(matchCss, "")
+            });
+        });
+    }
+
+    function dirContextFrom(fileContext) {
+        return path.dirname(
+            // The first file is 'stdin' when we're using the data option
+            fileContext === "stdin" ? resourcePath : fileContext
+        );
+    }
+
+    return (url, prev, done) => {
+        resolve(
+            dirContextFrom(
+                // node-sass returns UNIX-style paths
+                path.normalize(prev)
+            ),
+            url,
+            importsToResolve(utils.urlToRequest(url)),
+            done
+        );
+    };
+}
+
+module.exports = webpackImporter;