QStateMachine: replace a QPair with a small struct

The use of QPair made the return type of initializeAnimation()
so complicated, that the original author opted to declare the
pair on one line, then assign to it in the next, to keep below
the line length limit.

She also copied a member of the pair just so as to give it a
descriptive name.

Fix both by introducing a small result struct. It has a nicer
name, compared to the pair, but still port callers to use 'auto'.
The member names are descriptive enough now.

Saves more than 0.5KiB in text size on optimized GCC 4.9 Linux
AMD64 builds, too.

Change-Id: I7ed007ffa0fb16e182e38cd405cfd54da4e363fb
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Reviewed-by: Erik Verbruggen <erik.verbruggen@theqtcompany.com>

src/corelib/statemachine/qstatemachine.cpp

@@ -1512,20 +1512,18 @@ void QStateMachinePrivate::setError(QStateMachine::Error errorCode, QAbstractSta
 
 #ifndef QT_NO_ANIMATION
 
-QPair<QList<QAbstractAnimation*>, QList<QAbstractAnimation*> >
+QStateMachinePrivate::InitializeAnimationResult
 QStateMachinePrivate::initializeAnimation(QAbstractAnimation *abstractAnimation,
                                           const QPropertyAssignment &prop)
 {
-    QList<QAbstractAnimation*> handledAnimations;
-    QList<QAbstractAnimation*> localResetEndValues;
+    InitializeAnimationResult result;
     QAnimationGroup *group = qobject_cast<QAnimationGroup*>(abstractAnimation);
     if (group) {
         for (int i = 0; i < group->animationCount(); ++i) {
             QAbstractAnimation *animationChild = group->animationAt(i);
-            QPair<QList<QAbstractAnimation*>, QList<QAbstractAnimation*> > ret;
-            ret = initializeAnimation(animationChild, prop);
-            handledAnimations << ret.first;
-            localResetEndValues << ret.second;
+            const auto ret = initializeAnimation(animationChild, prop);
+            result.handledAnimations << ret.handledAnimations;
+            result.localResetEndValues << ret.localResetEndValues;
         }
     } else {
         QPropertyAnimation *animation = qobject_cast<QPropertyAnimation *>(abstractAnimation);
@@ -1536,12 +1534,12 @@ QStateMachinePrivate::initializeAnimation(QAbstractAnimation *abstractAnimation,
             // Only change end value if it is undefined
             if (!animation->endValue().isValid()) {
                 animation->setEndValue(prop.value);
-                localResetEndValues.append(animation);
+                result.localResetEndValues.append(animation);
             }
-            handledAnimations.append(animation);
+            result.handledAnimations.append(animation);
         }
     }
-    return qMakePair(handledAnimations, localResetEndValues);
+    return result;
 }
 
 void QStateMachinePrivate::_q_animationFinished()
@@ -1652,13 +1650,11 @@ void QStateMachinePrivate::initializeAnimations(QAbstractState *state, const QLi
         QAbstractAnimation *anim = selectedAnimations.at(i);
         QVector<QPropertyAssignment>::iterator it;
         for (it = assignments.begin(); it != assignments.end(); ) {
-            QPair<QList<QAbstractAnimation*>, QList<QAbstractAnimation*> > ret;
             const QPropertyAssignment &assn = *it;
-            ret = initializeAnimation(anim, assn);
-            QList<QAbstractAnimation*> handlers = ret.first;
-            if (!handlers.isEmpty()) {
-                for (int j = 0; j < handlers.size(); ++j) {
-                    QAbstractAnimation *a = handlers.at(j);
+            const auto ret = initializeAnimation(anim, assn);
+            if (!ret.handledAnimations.isEmpty()) {
+                for (int j = 0; j < ret.handledAnimations.size(); ++j) {
+                    QAbstractAnimation *a = ret.handledAnimations.at(j);
                     propertyForAnimation.insert(a, assn);
                     stateForAnimation.insert(a, state);
                     animationsForState[state].append(a);
@@ -1675,8 +1671,8 @@ void QStateMachinePrivate::initializeAnimations(QAbstractState *state, const QLi
             } else {
                 ++it;
             }
-            for (int j = 0; j < ret.second.size(); ++j)
-                resetAnimationEndValues.insert(ret.second.at(j));
+            for (int j = 0; j < ret.localResetEndValues.size(); ++j)
+                resetAnimationEndValues.insert(ret.localResetEndValues.at(j));
         }
         // We require that at least one animation is valid.
         // ### generalize

src/corelib/statemachine/qstatemachine_p.h

@@ -259,7 +259,18 @@ public:
 #ifndef QT_NO_ANIMATION
     bool animated;
 
-    QPair<QList<QAbstractAnimation*>, QList<QAbstractAnimation*> >
+    struct InitializeAnimationResult {
+        QList<QAbstractAnimation*> handledAnimations;
+        QList<QAbstractAnimation*> localResetEndValues;
+
+        void swap(InitializeAnimationResult &other) Q_DECL_NOTHROW
+        {
+            qSwap(handledAnimations,   other.handledAnimations);
+            qSwap(localResetEndValues, other.localResetEndValues);
+        }
+    };
+
+    InitializeAnimationResult
         initializeAnimation(QAbstractAnimation *abstractAnimation,
                             const QPropertyAssignment &prop);
 
@@ -307,6 +318,7 @@ public:
 
     static const Handler *handler;
 };
+Q_DECLARE_SHARED(QStateMachinePrivate::InitializeAnimationResult)
 
 Q_CORE_EXPORT const QStateMachinePrivate::Handler *qcoreStateMachineHandler();