memoise and bind member expression decorators - fixes #1296

src/babel/transformation/helpers/memoise-decorators.js

@@ -0,0 +1,33 @@
+import * as t from "../../types";
+
+export default function (decorators, scope) {
+  for (var i = 0; i < decorators.length; i++) {
+    var decorator = decorators[i];
+    var expression = decorator.expression;
+    if (!t.isMemberExpression(expression)) continue;
+
+    var temp = scope.generateMemoisedReference(expression.object);
+    var ref;
+
+    var nodes = [];
+
+    if (temp) {
+      ref = temp;
+      nodes.push(t.assignmentExpression("=", temp, expression.object));
+    } else {
+      ref = expression.object;
+    }
+
+    nodes.push(t.callExpression(
+      t.memberExpression(
+        t.memberExpression(ref, expression.property, expression.computed),
+        t.identifier("bind")
+      ),
+      [ref]
+    ));
+
+    decorator.expression = t.sequenceExpression(nodes);
+  }
+
+  return decorators;
+}

src/babel/transformation/transformers/es6/classes.js

@@ -1,3 +1,4 @@
+import memoiseDecorators from "../../helpers/memoise-decorators";
 import ReplaceSupers from "../../helpers/replace-supers";
 import * as nameMethod from "../../helpers/name-method";
 import * as defineMap from "../../helpers/define-map";
@@ -292,6 +293,10 @@ class ClassTransformer {
       var node = classBody[i];
       var path = classBodyPaths[i];
 
+      if (node.decorators) {
+        memoiseDecorators(node.decorators, this.scope);
+      }
+
       if (t.isMethodDefinition(node)) {
         var isConstructor = node.kind === "constructor";
         if (isConstructor) this.verifyConstructor(path);

src/babel/transformation/transformers/es7/decorators.js

@@ -1,3 +1,4 @@
+import memoiseDecorators from "../../helpers/memoise-decorators";
 import * as defineMap from "../../helpers/define-map";
 import * as t from "../../../types";
 
@@ -24,7 +25,9 @@ export function ObjectExpression(node, parent, scope, file) {
   var mutatorMap = {};
 
   for (var i = 0; i < node.properties.length; i++) {
-    defineMap.push(mutatorMap, node.properties[i], null, file);
+    var prop = node.properties[i];
+    if (prop.decorators) memoiseDecorators(prop.decorators, scope);
+    defineMap.push(mutatorMap, prop, null, file);
   }
 
   var obj = defineMap.toClassObject(mutatorMap);