feat(#13): add custom lookup path option

README.md

@@ -211,6 +211,24 @@ Style of exported classnames, the keys in your json.
 
 In lieu of a string, a custom function can generate the exported class names.
 
+### Resolve path alias
+
+You can rewrite paths for `composes/from` by using `resolve` options. 
+It's useful when you need to resolve custom path alias.
+
+```js
+postcss([
+  require("postcss-modules")({
+    resolve: function (file) {
+     return file.replace(/^@/, process.cwd());
+    },
+  }),
+]);
+```
+
+`resolve` may also return a `Promise<string>`.
+
+
 ## Integration with templates
 
 The plugin only transforms CSS classes to CSS modules.

index.d.ts

@@ -48,6 +48,8 @@ declare interface Options {
   root?: string;
 
   Loader?: typeof Loader;
+
+  resolve?: (file: string) => string | Promise<string>;
 }
 
 declare interface PostcssModulesPlugin {

src/index.js

@@ -85,7 +85,15 @@ module.exports = (opts = {}) => {
       const earlierPlugins = result.processor.plugins.slice(0, resultPluginIndex);
       const loaderPlugins = [...earlierPlugins, ...pluginList];
       const loader = getLoader(opts, loaderPlugins);
-      const parser = new Parser(loader.fetch.bind(loader));
+      const fetcher = ((file, relativeTo, depTrace) => {
+        const resolvedResult = (typeof opts.resolve === 'function' && opts.resolve(file));
+        const resolvedFile = resolvedResult instanceof Promise ? resolvedResult : Promise.resolve(resolvedResult);
+
+        return resolvedFile.then((f = file) => {
+          return loader.fetch.call(loader, f || file, relativeTo, depTrace);
+        });
+      });
+      const parser = new Parser(fetcher);
 
       await postcss([...pluginList, parser.plugin()]).process(css, {
         from: inputFile,

test/__snapshots__/test.js.snap

@@ -303,6 +303,19 @@ exports[`processes globalModulePaths option: processes globalModulePaths option
 
 exports[`processes hashPrefix option: processes hashPrefix option 1`] = `"._8xPWf {}"`;
 
+exports[`processes resolve option: processes resolve option 1`] = `
+"._composes_a_another-mixin {
+    display: flex;
+    height: 100px;
+    width: 200px;
+}._composes_a_hello {
+    foo: bar;
+}._compose_resolve_figure {
+    display: flex;
+}
+"
+`;
+
 exports[`processes values: processes values - CSS 1`] = `
 "
 

test/fixtures/in/compose.resolve.css

@@ -0,0 +1,4 @@
+.figure {
+    composes: hello from "test-fixture-in/composes.a.css";
+    display: flex;
+}

test/test.js

@@ -10,10 +10,10 @@ const fixturesPath = path.resolve(__dirname, "./fixtures");
 function createPlugin(name, processor) {
   const plugin = () => ({
     postcssPlugin: name,
-    Once: processor
-  })
-  plugin.postcss = true
-  return plugin
+    Once: processor,
+  });
+  plugin.postcss = true;
+  return plugin;
 }
 
 const cases = {
@@ -74,33 +74,35 @@ Object.keys(cases).forEach((name) => {
 
     const plugins = [
       autoprefixer,
-      createPlugin(
-        'validator-1',
-        (root) => {
-          if (rootsSeenBeforePlugin.has(root)) {
-            throw new Error('Plugin before ours was called multiple times.')
-          }
-          rootsSeenBeforePlugin.add(root);
-          root.prepend(`/* validator-1-start (${path.basename(root.source.input.file)}) */`);
-          root.append(`/* validator-1-end (${path.basename(root.source.input.file)}) */`);
+      createPlugin("validator-1", (root) => {
+        if (rootsSeenBeforePlugin.has(root)) {
+          throw new Error("Plugin before ours was called multiple times.");
         }
-      ),
+        rootsSeenBeforePlugin.add(root);
+        root.prepend(
+          `/* validator-1-start (${path.basename(root.source.input.file)}) */`
+        );
+        root.append(
+          `/* validator-1-end (${path.basename(root.source.input.file)}) */`
+        );
+      }),
       plugin({
         scopeBehaviour,
         generateScopedName: scopedNameGenerator,
         getJSON: () => {},
       }),
-      createPlugin(
-        'validator-2',
-        (root) => {
-          if (rootsSeenAfterPlugin.has(root)) {
-            throw new Error('Plugin after ours was called multiple times.')
-          }
-          rootsSeenAfterPlugin.add(root);
-          root.prepend(`/* validator-2-start (${path.basename(root.source.input.file)}) */`);
-          root.append(`/* validator-2-end (${path.basename(root.source.input.file)}) */`);
+      createPlugin("validator-2", (root) => {
+        if (rootsSeenAfterPlugin.has(root)) {
+          throw new Error("Plugin after ours was called multiple times.");
         }
-      ),
+        rootsSeenAfterPlugin.add(root);
+        root.prepend(
+          `/* validator-2-start (${path.basename(root.source.input.file)}) */`
+        );
+        root.append(
+          `/* validator-2-end (${path.basename(root.source.input.file)}) */`
+        );
+      }),
     ];
 
     const result = await postcss(plugins).process(source, { from: sourceFile });
@@ -252,7 +254,6 @@ it("processes localsConvention with dashes option", async () => {
   });
 });
 
-
 it("processes localsConvention with function option", async () => {
   const sourceFile = path.join(fixturesPath, "in", "camelCase.css");
   const source = fs.readFileSync(sourceFile).toString();
@@ -261,17 +262,20 @@ it("processes localsConvention with function option", async () => {
   if (fs.existsSync(jsonFile)) fs.unlinkSync(jsonFile);
 
   await postcss([
-    plugin({ generateScopedName, localsConvention: (className) => {
-      return className.replace('camel-case', 'cc');
-    } }),
+    plugin({
+      generateScopedName,
+      localsConvention: (className) => {
+        return className.replace("camel-case", "cc");
+      },
+    }),
   ]).process(source, { from: sourceFile });
 
   const json = fs.readFileSync(jsonFile).toString();
   fs.unlinkSync(jsonFile);
 
   expect(JSON.parse(json)).toMatchObject({
     cc: "_camelCase_camel-case",
-    'cc-extra': "_camelCase_camel-case-extra",
+    "cc-extra": "_camelCase_camel-case-extra",
     FooBar: "_camelCase_FooBar",
   });
 });
@@ -383,3 +387,23 @@ it("processes exportGlobals option", async () => {
     article: "_classes_article",
   });
 });
+
+it("processes resolve option", async () => {
+  const sourceFile = path.join(fixturesPath, "in", "compose.resolve.css");
+  const source = fs.readFileSync(sourceFile).toString();
+  let json;
+  const result = await postcss([
+    plugin({
+      generateScopedName,
+      resolve: async (file) => {
+        return file.replace(/test-fixture-in/, path.dirname(sourceFile));
+      },
+      getJSON: (_, result) => {
+        json = result;
+      },
+    }),
+  ]).process(source, { from: sourceFile });
+
+  expect(result.css).toMatchSnapshot("processes resolve option");
+  expect(json).toMatchObject({"figure": "_compose_resolve_figure _composes_a_hello"});
+});