Add support for await with the pipeline operator

packages/babel-plugin-proposal-pipeline-operator/src/index.js

@@ -15,6 +15,7 @@ export default function() {
 
         let optimizeArrow =
           t.isArrowFunctionExpression(right) && t.isExpression(right.body);
+        const isAwait = t.isAwaitExpression(right);
         let param;
 
         if (optimizeArrow) {
@@ -24,6 +25,11 @@ export default function() {
           } else if (params.length > 0) {
             optimizeArrow = false;
           }
+        } else if (isAwait) {
+          right.argument = t.sequenceExpression([
+            t.numericLiteral(0),
+            right.argument,
+          ]);
         } else if (t.isIdentifier(right, { name: "eval" })) {
           right = t.sequenceExpression([t.numericLiteral(0), right]);
         }
@@ -44,7 +50,9 @@ export default function() {
 
         const call = optimizeArrow
           ? right.body
-          : t.callExpression(right, [placeholder]);
+          : isAwait
+            ? t.awaitExpression(t.callExpression(right.argument, [placeholder]))
+            : t.callExpression(right, [placeholder]);
         path.replaceWith(
           t.sequenceExpression([
             t.assignmentExpression("=", placeholder, left),

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/pipeline-operator/async/actual.js

@@ -0,0 +1,5 @@
+var incPromise = (x) => Promise.resolve(x + 1);
+var double = (x) => x * 2;
+
+var result = async () => 10 |> await incPromise;
+var result2 = async () => 10 |> await incPromise |> double;

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/pipeline-operator/async/exec.js

@@ -0,0 +1,10 @@
+var incPromise = x => Promise.resolve(x + 1);
+var double = x => x * 2;
+
+var result = async () => 10 |> await incPromise;
+var result2 = async () => 10 |> await incPromise |> double;
+
+return Promise.all([result(), result2()]).then(([r, r2]) => {
+  assert.equal(r, 11);
+  assert.equal(r2, 22);
+});

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/pipeline-operator/async/expected.js

@@ -0,0 +1,15 @@
+var incPromise = x => Promise.resolve(x + 1);
+
+var double = x => x * 2;
+
+var result = async () => {
+  var _;
+
+  return _ = 10, await (0, incPromise)(_);
+};
+
+var result2 = async () => {
+  var _ref, _2;
+
+  return _ref = (_2 = 10, await (0, incPromise)(_2)), double(_ref);
+};

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/pipeline-operator/async/options.json

@@ -0,0 +1,5 @@
+{
+  "parserOpts": {
+    "allowReturnOutsideFunction": true
+  }
+}