feat: add supportn for pseudo classes

Author: andreypopp

examples/webpack/styles.react.css

@@ -7,6 +7,10 @@ Header {
   font-size: 200%;
   font-weight: bold;
   color: black;
+
+  :hover {
+    color: red;
+  }
 }
 
 Content {

src/index.js

@@ -7,6 +7,7 @@ import * as types from 'babel-types';
 import * as postcss from 'postcss';
 import * as LoaderUtils from 'loader-utils';
 import generate from 'babel-generator';
+import transformVariants, {isVariant} from './transformVariants';
 
 const LOADER = require.resolve('../webpack');
 
@@ -35,6 +36,7 @@ export function render(source: string, config: RenderConfig = {}): {js: string;
 
 function renderToCSS(source: string, config: RenderConfig): string {
   let root = postcss.parse(source);
+  root = transformVariants(root);
   root.walkRules(node => {
     let cssNode = node.clone();
     cssNode.selector = `:local(.${node.selector})`;
@@ -47,6 +49,9 @@ function renderToJS(source: string, config: RenderConfig): string {
   let root = postcss.parse(source);
   let statements = [];
   root.walkRules(node => {
+    if (isVariant(node)) {
+      return;
+    }
     statements.push(exportComponent(node.selector, 'div', node.selector));
   });
   statements.unshift(

src/transformVariants.js

@@ -0,0 +1,39 @@
+/**
+ * @copyright 2016-present, React CSS Components team
+ * @flow
+ */
+
+export default function transformVariants(root) {
+  let rules = [];
+  root.walkRules(rule => {
+    if (!isVariant(rule)) {
+      return;
+    }
+    let component = findComponent(rule);
+    rule = rule.remove().clone();
+    rule.selector = component.selector + rule.selector;
+    rules.push(rule);
+  });
+  root.append(...rules);
+  return root;
+}
+
+export function isVariant(node) {
+  return (
+    node.type === 'rule' &&
+    node.selector.charAt(0) === ':'
+  );
+}
+
+function findComponent(node) {
+  while (true) {
+    if (node.type === 'rule' && !isVariant(node)) {
+      return node;
+    }
+    if (!node.parent) {
+      break;
+    }
+    node = node.parent;
+  }
+  return null;
+}