From 07c87d469c4fbc7d7a6e9fad753d932dfda72989 Mon Sep 17 00:00:00 2001
From: azu <azuciao@gmail.com>
Date: Sun, 27 Mar 2016 13:35:27 +0900
Subject: [PATCH] Allow `transform` of Transformers to return promise

It allow Transformer#transform to work as async.
---
 src/TransformOutput.js | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/TransformOutput.js b/src/TransformOutput.js
index a0f316d4..61ed854a 100644
--- a/src/TransformOutput.js
+++ b/src/TransformOutput.js
@@ -31,12 +31,14 @@ function transform(transformer, transformCode, code) {
       transformCode,
       code,
     );
-    let map = null;
-    if (typeof result !== 'string') {
-      map = new SourceMapConsumer(result.map);
-      result = result.code;
-    }
-    return { result, map };
+    return Promise.resolve(result).then(result => {
+      let map = null;
+      if (typeof result !== 'string') {
+        map = new SourceMapConsumer(result.map);
+        result = result.code;
+      }
+      return { result, map };
+    });
   });
 }