From eb5654788b8c1662a4210e6c76c98abd509cf64f Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@kdab.com>
Date: Sun, 17 May 2015 16:44:07 +0200
Subject: Micro-optimize QSettingsPrivate::processChild() and its users

...by using QStringRef instead of QString, avoiding one
memory allocation in the case of spec != AllKeys and
key containing a '/'.

Also calls one less non-inline function, since
QStringRef::truncated() is inline.

Change-Id: Id5eb203006a3857508c5d3f4b729cde1a5170d58
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/io/qsettings.cpp     | 8 ++++----
 src/corelib/io/qsettings_mac.cpp | 2 +-
 src/corelib/io/qsettings_p.h     | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

(limited to 'src/corelib/io')

diff --git a/src/corelib/io/qsettings.cpp b/src/corelib/io/qsettings.cpp
index 977cc107e7..2ae89af356 100644
--- a/src/corelib/io/qsettings.cpp
+++ b/src/corelib/io/qsettings.cpp
@@ -299,7 +299,7 @@ QSettingsPrivate *QSettingsPrivate::create(const QString &fileName, QSettings::F
 }
 #endif
 
-void QSettingsPrivate::processChild(QString key, ChildSpec spec, QMap<QString, QString> &result)
+void QSettingsPrivate::processChild(QStringRef key, ChildSpec spec, QMap<QString, QString> &result)
 {
     if (spec != AllKeys) {
         int slashPos = key.indexOf(QLatin1Char('/'));
@@ -312,7 +312,7 @@ void QSettingsPrivate::processChild(QString key, ChildSpec spec, QMap<QString, Q
             key.truncate(slashPos);
         }
     }
-    result.insert(key, QString());
+    result.insert(key.toString(), QString());
 }
 
 void QSettingsPrivate::beginGroupOrArray(const QSettingsGroup &group)
@@ -1292,14 +1292,14 @@ QStringList QConfFileSettingsPrivate::children(const QString &prefix, ChildSpec
                     &confFile->originalKeys)->lowerBound( thePrefix);
             while (j != confFile->originalKeys.constEnd() && j.key().startsWith(thePrefix)) {
                 if (!confFile->removedKeys.contains(j.key()))
-                    processChild(j.key().originalCaseKey().mid(startPos), spec, result);
+                    processChild(j.key().originalCaseKey().midRef(startPos), spec, result);
                 ++j;
             }
 
             j = const_cast<const ParsedSettingsMap *>(
                     &confFile->addedKeys)->lowerBound(thePrefix);
             while (j != confFile->addedKeys.constEnd() && j.key().startsWith(thePrefix)) {
-                processChild(j.key().originalCaseKey().mid(startPos), spec, result);
+                processChild(j.key().originalCaseKey().midRef(startPos), spec, result);
                 ++j;
             }
 
diff --git a/src/corelib/io/qsettings_mac.cpp b/src/corelib/io/qsettings_mac.cpp
index 51321c49e7..083722869f 100644
--- a/src/corelib/io/qsettings_mac.cpp
+++ b/src/corelib/io/qsettings_mac.cpp
@@ -505,7 +505,7 @@ QStringList QMacSettingsPrivate::children(const QString &prefix, ChildSpec spec)
                     QString currentKey =
                             qtKey(static_cast<CFStringRef>(CFArrayGetValueAtIndex(cfarray, k)));
                     if (currentKey.startsWith(prefix))
-                        processChild(currentKey.mid(startPos), spec, result);
+                        processChild(currentKey.midRef(startPos), spec, result);
                 }
             }
         }
diff --git a/src/corelib/io/qsettings_p.h b/src/corelib/io/qsettings_p.h
index 93d63fd411..004751182c 100644
--- a/src/corelib/io/qsettings_p.h
+++ b/src/corelib/io/qsettings_p.h
@@ -211,7 +211,7 @@ public:
                                         const QString &organization, const QString &application);
     static QSettingsPrivate *create(const QString &fileName, QSettings::Format format);
 
-    static void processChild(QString key, ChildSpec spec, QMap<QString, QString> &result);
+    static void processChild(QStringRef key, ChildSpec spec, QMap<QString, QString> &result);
 
     // Variant streaming functions
     static QStringList variantListToStringList(const QVariantList &l);
-- 
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