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.

4 files changed, 35 insertions, 14 deletions

diff --git a/src/declarative/qml/qmlcontext.cpp b/src/declarative/qml/qmlcontext.cpp
index 365ad6d..8a2732d 100644
--- a/src/declarative/qml/qmlcontext.cpp
+++ b/src/declarative/qml/qmlcontext.cpp
@@ -55,7 +55,7 @@ QT_BEGIN_NAMESPACE
 
 QmlContextPrivate::QmlContextPrivate()
 : parent(0), engine(0), isInternal(false), notifyIndex(-1), 
-  highPriorityCount(0), idValues(0), idValueCount(0)
+  highPriorityCount(0), expressions(0), idValues(0), idValueCount(0)
 {
 }
 
@@ -278,11 +278,15 @@ QmlContext::~QmlContext()
         (*iter)->d_func()->parent = 0;
     }
 
-    for (QSet<QmlExpression *>::ConstIterator iter = 
-            d->childExpressions.begin();
-            iter != d->childExpressions.end();
-            ++iter) {
-        (*iter)->d_func()->ctxt = 0;
+    QmlExpressionPrivate *expression = d->expressions;
+    while (expression) {
+        QmlExpressionPrivate *nextExpression = expression->nextExpression;
+
+        expression->ctxt = 0;
+        expression->prevExpression = 0;
+        expression->nextExpression = 0;
+
+        expression = nextExpression;
     }
 
     for (int ii = 0; ii < d->contextObjects.count(); ++ii) {
diff --git a/src/declarative/qml/qmlcontext_p.h b/src/declarative/qml/qmlcontext_p.h
index 4240c8a..60655ae 100644
--- a/src/declarative/qml/qmlcontext_p.h
+++ b/src/declarative/qml/qmlcontext_p.h
@@ -67,6 +67,7 @@ class QmlContext;
 class QmlExpression;
 class QmlEngine;
 class QmlExpression;
+class QmlExpressionPrivate;
 
 class QmlContextPrivate : public QObjectPrivate
 {
@@ -102,7 +103,8 @@ public:
 
     void invalidateEngines();
     QSet<QmlContext *> childContexts;
-    QSet<QmlExpression *> childExpressions;
+
+    QmlExpressionPrivate *expressions;
 
     QmlSimpleDeclarativeData contextData;
     QObjectList contextObjects;
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;
+    }
 }
 
 /*!
diff --git a/src/declarative/qml/qmlexpression_p.h b/src/declarative/qml/qmlexpression_p.h
index 5ecc24d..f607898 100644
--- a/src/declarative/qml/qmlexpression_p.h
+++ b/src/declarative/qml/qmlexpression_p.h
@@ -70,6 +70,10 @@ public:
     QmlExpressionPrivate();
     ~QmlExpressionPrivate();
 
+    // Forms the QmlContext "expressions" linked list
+    QmlExpressionPrivate *nextExpression;
+    QmlExpressionPrivate **prevExpression;
+
     enum CompiledDataType {
         BasicScriptEngineData = 1,
         PreTransformedQtScriptData = 2