Use a linked list instead of a QSet<> to track expressions

While the QSet<> wasn't that expensive, the QmlContext only tracks the
expressions to stop programmers doing something "stupid" so any overhead is
unacceptable.  This does give a measurable improvement.

1 files changed, 18 insertions, 7 deletions

diff --git a/src/declarative/qml/qmlexpression.cpp b/src/declarative/qml/qmlexpression.cpp
index 148ff71..3206734 100644
--- a/src/declarative/qml/qmlexpression.cpp
+++ b/src/declarative/qml/qmlexpression.cpp
@@ -51,7 +51,7 @@ Q_DECLARE_METATYPE(QList<QObject *>);
 QT_BEGIN_NAMESPACE
 
 QmlExpressionPrivate::QmlExpressionPrivate()
-: ctxt(0), expressionFunctionValid(false), expressionRewritten(false), sseData(0), me(0), trackChange(true), line(-1), guardList(0), guardListLength(0)
+: nextExpression(0), prevExpression(0), ctxt(0), expressionFunctionValid(false), expressionRewritten(false), sseData(0), me(0), trackChange(true), line(-1), guardList(0), guardListLength(0)
 {
 }
 
@@ -63,8 +63,12 @@ void QmlExpressionPrivate::init(QmlContext *ctxt, const QString &expr,
     expression = expr;
 
     this->ctxt = ctxt;
-    if (ctxt)
-        ctxt->d_func()->childExpressions.insert(q);
+    if (ctxt) {
+        QmlContextPrivate *cp = ctxt->d_func();
+        nextExpression = cp->expressions;
+        prevExpression = &cp->expressions;
+        cp->expressions = this;
+    }
     this->me = me;
 }
 
@@ -84,8 +88,12 @@ void QmlExpressionPrivate::init(QmlContext *ctxt, void *expr, QmlRefCount *rc,
     }
 
     this->ctxt = ctxt;
-    if (ctxt)
-        ctxt->d_func()->childExpressions.insert(q);
+    if (ctxt) {
+        QmlContextPrivate *cp = ctxt->d_func();
+        nextExpression = cp->expressions;
+        prevExpression = &cp->expressions;
+        cp->expressions = this;
+    }
     this->me = me;
 }
 
@@ -152,8 +160,11 @@ QmlExpression::QmlExpression(QmlContext *ctxt, const QString &expression,
 QmlExpression::~QmlExpression()
 {
     Q_D(QmlExpression);
-    if (d->ctxt)
-        d->ctxt->d_func()->childExpressions.remove(this);
+    if (d->prevExpression) {
+        *(d->prevExpression) = d->nextExpression;
+        if (d->nextExpression) 
+            d->nextExpression->prevExpression = d->prevExpression;
+    }
 }
 
 /*!