From 7461ed5227e3002c4a6f74d458aa0255b7c1217d Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@nokia.com>
Date: Tue, 26 Jan 2010 17:32:25 +0100
Subject: Optimise QStringList::join by pre-allocating the final size.

This avoids a number of reallocations due to appending.

This patch was contributed to us.

Task-number: QTBUG-3242
Reviewed-by: Thiago Macieira
---
 src/corelib/tools/qstringlist.cpp | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/corelib/tools/qstringlist.cpp b/src/corelib/tools/qstringlist.cpp
index 4b0f488..e9bdf57 100644
--- a/src/corelib/tools/qstringlist.cpp
+++ b/src/corelib/tools/qstringlist.cpp
@@ -404,7 +404,17 @@ void QtPrivate::QStringList_replaceInStrings(QStringList *that, const QRegExp &r
 */
 QString QtPrivate::QStringList_join(const QStringList *that, const QString &sep)
 {
+    int totalLength = 0;
+    const int size = that->size();
+
+    for (int i = 0; i < size; ++i)
+        totalLength += that->at(i).size();
+
+    if(size > 0)
+        totalLength += sep.size() * (size - 1);
+
     QString res;
+    res.reserve(totalLength);
     for (int i = 0; i < that->size(); ++i) {
         if (i)
             res += sep;
-- 
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