From 5f42326f34a1e2ee2f43fb69a07cd2746de08df6 Mon Sep 17 00:00:00 2001
From: Charlie Somerville <charlie@charliesomerville.com>
Date: Sun, 18 Jan 2015 00:44:14 +1100
Subject: [PATCH 1/2] set the rightAssociative flag on _exponent

---
 acorn.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/acorn.js b/acorn.js
index 692e6c6796..a3be8bdb90 100644
--- a/acorn.js
+++ b/acorn.js
@@ -469,7 +469,7 @@
 
   // '*' may be multiply or have special meaning in ES6
   var _star = {binop: 10, beforeExpr: true};
-  var _exponent = {binop: 11, beforeExpr: true};
+  var _exponent = {binop: 11, beforeExpr: true, rightAssociative: true};
 
   // '<', '>' may be relational or have special meaning in JSX
   var _lt = {binop: 7, beforeExpr: true}, _gt = {binop: 7, beforeExpr: true};

From b51118c3fcd05cbd0cce58826f4c561a3a57e3d3 Mon Sep 17 00:00:00 2001
From: Charlie Somerville <charlie@charliesomerville.com>
Date: Sun, 18 Jan 2015 00:42:43 +1100
Subject: [PATCH 2/2] use right recursion for right associative operators

---
 acorn.js | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/acorn.js b/acorn.js
index a3be8bdb90..3cf3f06e87 100644
--- a/acorn.js
+++ b/acorn.js
@@ -2515,9 +2515,17 @@
         var op = tokType;
         next();
         var start = storeCurrentPos();
-        node.right = parseExprOp(parseMaybeUnary(), start, prec, noIn);
+        if(op.rightAssociative) {
+          node.right = parseExprOp(parseMaybeUnary(), start, prec - 1, noIn);
+        } else {
+          node.right = parseExprOp(parseMaybeUnary(), start, prec, noIn);
+        }
         finishNode(node, (op === _logicalOR || op === _logicalAND) ? "LogicalExpression" : "BinaryExpression");
-        return parseExprOp(node, leftStart, minPrec, noIn);
+        if(op.rightAssociative) {
+          return node;
+        } else {
+          return parseExprOp(node, leftStart, minPrec, noIn);
+        }
       }
     }
     return left;