From eca96f1905045b93a6d0ee9ea26c5ec16ee24353 Mon Sep 17 00:00:00 2001
From: alexlamsl <alexlamsl@gmail.com>
Date: Fri, 16 Jun 2017 15:01:00 +0800
Subject: [PATCH] in-place `join_vars`

---
 lib/compress.js | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/lib/compress.js b/lib/compress.js
index 4f92f289..3a361521 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -679,7 +679,7 @@ merge(Compressor.prototype, {
                 statements = sequencesize(statements, compressor);
             }
             if (compressor.option("join_vars")) {
-                statements = join_consecutive_vars(statements, compressor);
+                join_consecutive_vars(statements, compressor);
             }
             if (compressor.option("collapse_vars")) {
                 collapse(statements, compressor);
@@ -1173,8 +1173,9 @@ merge(Compressor.prototype, {
         };
 
         function join_consecutive_vars(statements, compressor) {
-            var prev = null;
-            return statements.reduce(function(a, stat){
+            for (var i = 0, j = -1, len = statements.length; i < len; i++) {
+                var stat = statements[i];
+                var prev = statements[j];
                 if (stat instanceof AST_Definitions && prev && prev.TYPE == stat.TYPE) {
                     prev.definitions = prev.definitions.concat(stat.definitions);
                     CHANGED = true;
@@ -1183,21 +1184,18 @@ merge(Compressor.prototype, {
                          && prev instanceof AST_Var
                          && (!stat.init || stat.init.TYPE == prev.TYPE)) {
                     CHANGED = true;
-                    a.pop();
                     if (stat.init) {
                         stat.init.definitions = prev.definitions.concat(stat.init.definitions);
                     } else {
                         stat.init = prev;
                     }
-                    a.push(stat);
-                    prev = stat;
+                    statements[j] = stat;
                 }
                 else {
-                    prev = stat;
-                    a.push(stat);
+                    statements[++j] = stat;
                 }
-                return a;
-            }, []);
+            }
+            statements.length = j + 1;
         };
 
     };