support exponentiation operator (#4593)

3 files changed, 18 insertions, 4 deletions

diff --git a/lib/compress.js b/lib/compress.js
index d79c1cce..ac380cf3 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -4168,6 +4168,9 @@ merge(Compressor.prototype, {
               case "<=" : result = left <=  right; break;
               case ">"  : result = left >   right; break;
               case ">=" : result = left >=  right; break;
+              case "**":
+                result = Math.pow(left, right);
+                break;
               case "in":
                 if (right && typeof right == "object" && HOP(right, left)) {
                     result = true;
diff --git a/lib/output.js b/lib/output.js
index f2748e9e..8521d7ef 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -684,6 +684,10 @@ function OutputStream(options) {
 
     PARENS(AST_Unary, function(output) {
         var p = output.parent();
+        // (-x) ** y
+        if (p instanceof AST_Binary) return p.operator == "**" && p.left === this;
+        // (x++).toString(3)
+        // (typeof x).length
         return (p instanceof AST_Call || p instanceof AST_PropAccess) && p.expression === this;
     });
 
@@ -722,11 +726,14 @@ function OutputStream(options) {
         var p = output.parent();
         // await (foo && bar)
         if (p instanceof AST_Await) return true;
-        // this deals with precedence: 3 * (2 + 1)
+        // this deals with precedence:
+        //   3 * (2 + 1)
+        //   3 - (2 - 1)
+        //   (1 ** 2) ** 3
         if (p instanceof AST_Binary) {
             var po = p.operator, pp = PRECEDENCE[po];
             var so = this.operator, sp = PRECEDENCE[so];
-            return pp > sp || (pp == sp && this === p.right);
+            return pp > sp || (pp == sp && this === p[po == "**" ? "left" : "right"]);
         }
         // (foo && bar)()
         if (p instanceof AST_Call) return p.expression === this;
@@ -818,6 +825,8 @@ function OutputStream(options) {
 
     PARENS(AST_Await, function(output) {
         var p = output.parent();
+        // (await x) ** y
+        if (p instanceof AST_Binary) return p.operator == "**" && p.left === this;
         // new (await foo)
         // (await foo)(bar)
         if (p instanceof AST_Call) return p.expression === this;
diff --git a/lib/parse.js b/lib/parse.js
index 64307a95..38c56d8f 100644
--- a/lib/parse.js
+++ b/lib/parse.js
@@ -81,6 +81,7 @@ var OPERATORS = makePredicate([
     "*",
     "/",
     "%",
+    "**",
     ">>",
     "<<",
     ">>>",
@@ -630,7 +631,8 @@ var PRECEDENCE = function(a, ret) {
     ["<", ">", "<=", ">=", "in", "instanceof"],
     [">>", "<<", ">>>"],
     ["+", "-"],
-    ["*", "/", "%"]
+    ["*", "/", "%"],
+    ["**"],
 ], {});
 
 var ATOMIC_START_TOKEN = makePredicate("atom bigint num regexp string");
@@ -1860,7 +1862,7 @@ function parse($TEXT, options) {
         var prec = op != null ? PRECEDENCE[op] : null;
         if (prec != null && prec > min_prec) {
             next();
-            var right = expr_op(maybe_await(), prec, no_in);
+            var right = expr_op(maybe_await(), op == "**" ? prec - 1 : prec, no_in);
             return expr_op(new AST_Binary({
                 start    : left.start,
                 left     : left,