From c4fb5a5e403e419ab6b440e55cc18a5a0378f463 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Thu, 22 Jan 2015 17:19:22 +1100
Subject: [PATCH] more compact async to generator helper

---
 .../templates/async-to-generator.js           | 37 +++++++------------
 .../expression/expected.js                    | 36 ++++++++----------
 .../statement/expected.js                     | 36 ++++++++----------
 3 files changed, 44 insertions(+), 65 deletions(-)

diff --git a/lib/6to5/transformation/templates/async-to-generator.js b/lib/6to5/transformation/templates/async-to-generator.js
index aeacb62f04..f03547d2fe 100644
--- a/lib/6to5/transformation/templates/async-to-generator.js
+++ b/lib/6to5/transformation/templates/async-to-generator.js
@@ -2,36 +2,27 @@
   return function () {
     var gen = fn.apply(this, arguments);
 
-    return new Promise(function (resolve, reject) {
-      function step(getNext) {
-        var next;
+    return new Promise(function(resolve, reject) {
+      var callNext = step.bind(gen.next);
+      var callThrow = step.bind(gen.throw);
 
+      function step(arg) {
         try {
-          next = getNext();
-        } catch(e) {
-          reject(e);
+          var info = this(arg);
+          var value = info.value;
+        } catch (error) {
+          reject(error);
           return;
         }
 
-        if (next.done) {
-          resolve(next.value);
-          return;
+        if (info.done) {
+          resolve(value);
+        } else {
+          Promise.resolve(value).then(callNext, callThrow);
         }
-
-        Promise.resolve(next.value).then(function (v) {
-          step(function () {
-            return gen.next(v);
-          });
-        }, function (e) {
-          step(function () {
-            return gen["throw"](e);
-          });
-        });
       }
 
-      step(function () {
-        return gen.next();
-      });
+      callNext();
     });
-  }
+  };
 })
diff --git a/test/fixtures/transformation/optional-async-to-generator/expression/expected.js b/test/fixtures/transformation/optional-async-to-generator/expression/expected.js
index faf8868b28..cb5f6a8c4c 100644
--- a/test/fixtures/transformation/optional-async-to-generator/expression/expected.js
+++ b/test/fixtures/transformation/optional-async-to-generator/expression/expected.js
@@ -5,34 +5,28 @@ var _asyncToGenerator = function (fn) {
     var gen = fn.apply(this, arguments);
 
     return new Promise(function (resolve, reject) {
-      function step(getNext) {
-        var next;
+      var callNext = step.bind(gen.next);
+
+      var callThrow = step.bind(gen["throw"]);
+
+      function step(arg) {
         try {
-          next = getNext();
-        } catch (e) {
-          reject(e);
+          var info = this(arg);
+
+          var value = info.value;
+        } catch (error) {
+          reject(error);
 
           return;
         }
-        if (next.done) {
-          resolve(next.value);
-
-          return;
+        if (info.done) {
+          resolve(value);
+        } else {
+          Promise.resolve(value).then(callNext, callThrow);
         }
-        Promise.resolve(next.value).then(function (v) {
-          step(function () {
-            return gen.next(v);
-          });
-        }, function (e) {
-          step(function () {
-            return gen["throw"](e);
-          });
-        });
       }
 
-      step(function () {
-        return gen.next();
-      });
+      callNext();
     });
   };
 };
diff --git a/test/fixtures/transformation/optional-async-to-generator/statement/expected.js b/test/fixtures/transformation/optional-async-to-generator/statement/expected.js
index faf8868b28..cb5f6a8c4c 100644
--- a/test/fixtures/transformation/optional-async-to-generator/statement/expected.js
+++ b/test/fixtures/transformation/optional-async-to-generator/statement/expected.js
@@ -5,34 +5,28 @@ var _asyncToGenerator = function (fn) {
     var gen = fn.apply(this, arguments);
 
     return new Promise(function (resolve, reject) {
-      function step(getNext) {
-        var next;
+      var callNext = step.bind(gen.next);
+
+      var callThrow = step.bind(gen["throw"]);
+
+      function step(arg) {
         try {
-          next = getNext();
-        } catch (e) {
-          reject(e);
+          var info = this(arg);
+
+          var value = info.value;
+        } catch (error) {
+          reject(error);
 
           return;
         }
-        if (next.done) {
-          resolve(next.value);
-
-          return;
+        if (info.done) {
+          resolve(value);
+        } else {
+          Promise.resolve(value).then(callNext, callThrow);
         }
-        Promise.resolve(next.value).then(function (v) {
-          step(function () {
-            return gen.next(v);
-          });
-        }, function (e) {
-          step(function () {
-            return gen["throw"](e);
-          });
-        });
       }
 
-      step(function () {
-        return gen.next();
-      });
+      callNext();
     });
   };
 };