refactor: switch to Once() API.

Author: ludofischer

src/index.js

@@ -8,20 +8,25 @@ function pluginCreator(opts) {
     mediaQueries: false,
     selectors: false
   }, opts);
+
   return {
     postcssPlugin: 'postcss-calc',
-    Declaration(node, {result}) {
-      transform(node, "value", options, result);
-    },
-    AtRule(node, {result}) {
-      if (options.mediaQueries) {
-        transform(node, "params", options, result);
-      }
-    },
-    Rule(node, {result}) {
-      if (options.selectors) {
-        transform(node, "selector", options, result);
-      }
+    Once(css, { result }) {
+      css.walk(node => {
+        const { type } = node;
+
+        if (type === 'decl') {
+          transform(node, "value", options, result);
+        }
+        
+        if (type === 'atrule' && options.mediaQueries) {
+          transform(node, "params", options, result);
+        }
+
+        if (type === 'rule' && options.selectors) {
+          transform(node, "selector", options, result);
+        }
+      });
     }
   }
 }

src/lib/transform.js

@@ -8,7 +8,6 @@ import reducer from './reducer';
 import stringifier from './stringifier';
 
 const MATCH_CALC = /((?:-(moz|webkit)-)?calc)/i;
-const processed = Symbol('postcss-calc-processed');
 
 function transformValue(value, options, result, item) {
   return valueParser(value).walk(node => {
@@ -60,9 +59,6 @@ function transformSelector(value, options, result, item) {
 }
 
 export default (node, property, options, result) => {
-  if (node[processed]) {
-    return;
-  }
   const value = property === "selector"
     ? transformSelector(node[property], options, result, node)
     : transformValue(node[property], options, result, node);
@@ -78,5 +74,4 @@ export default (node, property, options, result) => {
   } else {
     node[property] = value;
   }
-  node[processed] = true;
 };