From 9ce797dd34ac16bd5b29efbedae2751a177e0859 Mon Sep 17 00:00:00 2001
From: Justin Ridgewell <justin@ridgewell.name>
Date: Sat, 3 Jun 2017 23:52:04 -0400
Subject: [PATCH] Reduce context memoization when possible

---
 .../src/index.js                                 | 16 ++++++++--------
 .../fixtures/general/function-call/expected.js   |  4 ++--
 .../test/fixtures/general/memoize/expected.js    | 10 +++++-----
 3 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/packages/babel-plugin-transform-optional-chaining/src/index.js b/packages/babel-plugin-transform-optional-chaining/src/index.js
index 9c4b7805a5..826a5b8a4c 100644
--- a/packages/babel-plugin-transform-optional-chaining/src/index.js
+++ b/packages/babel-plugin-transform-optional-chaining/src/index.js
@@ -29,16 +29,14 @@ export default function ({ types: t }) {
       if (loose && atCall) {
         // If we are using a loose transform (avoiding a Function#call) and we are at the call,
         // we can avoid a needless memoize.
-        ref = chain;
-        check = ref;
+        check = ref = chain;
       } else {
         ref = scope.maybeGenerateMemoised(chain);
         if (ref) {
           check = t.assignmentExpression("=", ref, chain);
           node[replaceKey] = ref;
         } else {
-          ref = chain;
-          check = chain;
+          check = ref = chain;
         }
       }
 
@@ -53,10 +51,12 @@ export default function ({ types: t }) {
           // Otherwise, we need to memoize the context object, and change the call into a Function#call.
           // `a.?b.?()` translates roughly to `(_b = _a.b) != null && _b.call(_a)`
           const { object } = chain;
-          const context = scope.generateUidIdentifierBasedOnNode(object);
-
-          scope.push({ id: context });
-          chain.object = t.assignmentExpression("=", context, object);
+          let context = scope.maybeGenerateMemoised(object);
+          if (context) {
+            chain.object = t.assignmentExpression("=", context, object);
+          } else {
+            context = object;
+          }
 
           node.arguments.unshift(context);
           node.callee = t.memberExpression(node.callee, t.identifier("call"));
diff --git a/packages/babel-plugin-transform-optional-chaining/test/fixtures/general/function-call/expected.js b/packages/babel-plugin-transform-optional-chaining/test/fixtures/general/function-call/expected.js
index 1df03edc8c..ca85c85dac 100644
--- a/packages/babel-plugin-transform-optional-chaining/test/fixtures/general/function-call/expected.js
+++ b/packages/babel-plugin-transform-optional-chaining/test/fixtures/general/function-call/expected.js
@@ -1,4 +1,4 @@
-var _foo, _foo2, _foo$bar, _foo3, _foo4, _foo4$bar, _foo5;
+var _foo, _foo2, _foo$bar, _foo3, _foo4, _foo4$bar;
 
 (_foo = foo) == null ? void 0 : _foo(foo);
 
@@ -6,4 +6,4 @@ var _foo, _foo2, _foo$bar, _foo3, _foo4, _foo4$bar, _foo5;
 
 (_foo$bar = (_foo3 = foo).bar) == null ? void 0 : _foo$bar.call(_foo3, foo.bar, false);
 
-(_foo4 = foo) == null ? void 0 : (_foo4$bar = (_foo5 = _foo4).bar) == null ? void 0 : _foo4$bar.call(_foo5, foo.bar, true);
\ No newline at end of file
+(_foo4 = foo) == null ? void 0 : (_foo4$bar = _foo4.bar) == null ? void 0 : _foo4$bar.call(_foo4, foo.bar, true);
\ No newline at end of file
diff --git a/packages/babel-plugin-transform-optional-chaining/test/fixtures/general/memoize/expected.js b/packages/babel-plugin-transform-optional-chaining/test/fixtures/general/memoize/expected.js
index d02f52f934..2e24fb6f41 100644
--- a/packages/babel-plugin-transform-optional-chaining/test/fixtures/general/memoize/expected.js
+++ b/packages/babel-plugin-transform-optional-chaining/test/fixtures/general/memoize/expected.js
@@ -1,5 +1,5 @@
 function test(foo) {
-  var _foo$bar, _foo$bar2, _foo, _foo$bar3, _foo2, _foo$bar4, _foo$bar5, _foo$bar6, _foo$bar6$baz, _foo$bar7, _foo$bar8, _foo$bar8$baz, _foo$bar9;
+  var _foo$bar, _foo$bar2, _foo$bar3, _foo$bar4, _foo$bar5, _foo$bar6, _foo$bar6$baz, _foo$bar7, _foo$bar7$baz;
 
   foo == null ? void 0 : foo.bar;
 
@@ -9,15 +9,15 @@ function test(foo) {
 
   foo == null ? void 0 : foo.bar();
 
-  (_foo$bar2 = (_foo = foo).bar) == null ? void 0 : _foo$bar2.call(_foo, foo.bar, false);
+  (_foo$bar2 = foo.bar) == null ? void 0 : _foo$bar2.call(foo, foo.bar, false);
 
-  foo == null ? void 0 : (_foo$bar3 = (_foo2 = foo).bar) == null ? void 0 : _foo$bar3.call(_foo2, foo.bar, true);
+  foo == null ? void 0 : (_foo$bar3 = foo.bar) == null ? void 0 : _foo$bar3.call(foo, foo.bar, true);
 
   (_foo$bar4 = foo.bar) == null ? void 0 : _foo$bar4.baz(foo.bar, false);
 
   foo == null ? void 0 : (_foo$bar5 = foo.bar) == null ? void 0 : _foo$bar5.baz(foo.bar, true);
 
-  (_foo$bar6 = foo.bar) == null ? void 0 : (_foo$bar6$baz = (_foo$bar7 = _foo$bar6).baz) == null ? void 0 : _foo$bar6$baz.call(_foo$bar7, foo.bar, false);
+  (_foo$bar6 = foo.bar) == null ? void 0 : (_foo$bar6$baz = _foo$bar6.baz) == null ? void 0 : _foo$bar6$baz.call(_foo$bar6, foo.bar, false);
 
-  foo == null ? void 0 : (_foo$bar8 = foo.bar) == null ? void 0 : (_foo$bar8$baz = (_foo$bar9 = _foo$bar8).baz) == null ? void 0 : _foo$bar8$baz.call(_foo$bar9, foo.bar, true);
+  foo == null ? void 0 : (_foo$bar7 = foo.bar) == null ? void 0 : (_foo$bar7$baz = _foo$bar7.baz) == null ? void 0 : _foo$bar7$baz.call(_foo$bar7, foo.bar, true);
 }
\ No newline at end of file