Use minimal javascript expression for bound signals

Previously, QQmlBoundSignal used QQmlExpression internally.  This
commit adds a new, more optimal QQmlJavaScriptExpression subclass
specifically designed for QQmlBoundSignal, and converts the code
to use it instead of QQmlExpression where appropriate.

Task-number: QTBUG-24460
Change-Id: I2865a119ce840235e27a7722d8052ca61c265f69
Reviewed-by: Michael Brasser <michael.brasser@nokia.com>

1 files changed, 47 insertions, 10 deletions

diff --git a/src/qml/qml/qqmlboundsignal_p.h b/src/qml/qml/qqmlboundsignal_p.h
index 5fc8c3522f..22cc5a9f83 100644
--- a/src/qml/qml/qqmlboundsignal_p.h
+++ b/src/qml/qml/qqmlboundsignal_p.h
@@ -53,15 +53,52 @@
 // We mean it.
 //
 
-#include "qqmlexpression.h"
-
 #include <QtCore/qmetaobject.h>
 
+#include <private/qqmlabstractexpression_p.h>
+#include <private/qqmljavascriptexpression_p.h>
 #include <private/qqmlnotifier_p.h>
 #include <private/qobject_p.h>
 
 QT_BEGIN_NAMESPACE
 
+class Q_QML_PRIVATE_EXPORT QQmlBoundSignalExpression : public QQmlAbstractExpression, public QQmlJavaScriptExpression
+{
+public:
+    QQmlBoundSignalExpression(QQmlContextData *ctxt, QObject *scope, const QByteArray &expression,
+                              bool isRewritten, const QString &fileName, int line, int column);
+    QQmlBoundSignalExpression(QQmlContextData *ctxt, QObject *scope, const QString &expression,
+                              bool isRewritten, const QString &fileName, int line, int column);
+    ~QQmlBoundSignalExpression();
+
+    // "inherited" from QQmlJavaScriptExpression.
+    static QString expressionIdentifier(QQmlJavaScriptExpression *);
+    static void expressionChanged(QQmlJavaScriptExpression *);
+
+    // evaluation of a bound signal expression doesn't return any value
+    void evaluate(QObject *secondaryScope = 0);
+
+    QString sourceFile() const { return m_fileName; }
+    int lineNumber() const { return m_line; }
+    int columnNumber() const { return m_column; }
+    QString expression() const { return m_expression; }
+
+    QQmlEngine *engine() const { return context() ? context()->engine : 0; }
+
+private:
+    v8::Persistent<v8::Object> m_v8qmlscope;
+    v8::Persistent<v8::Function> m_v8function;
+
+    QString m_expression;
+    QString m_functionName; // hint for debugger
+    QString m_fileName;
+    int m_line;
+    int m_column;
+
+    bool m_expressionFunctionValid:1;
+    bool m_expressionFunctionRewritten:1;
+};
+
 class Q_QML_EXPORT QQmlAbstractBoundSignal
 {
 public:
@@ -69,8 +106,8 @@ public:
     virtual ~QQmlAbstractBoundSignal();
 
     virtual int index() const = 0;
-    virtual QQmlExpression *expression() const = 0;
-    virtual QQmlExpression *setExpression(QQmlExpression *) = 0;
+    virtual QQmlBoundSignalExpression *expression() const = 0;
+    virtual QQmlBoundSignalExpression *setExpression(QQmlBoundSignalExpression *) = 0;
     virtual QObject *object() = 0;
 
     void addToObject();
@@ -93,8 +130,8 @@ public:
 
     int index() const;
 
-    QQmlExpression *expression() const;
-    QQmlExpression *setExpression(QQmlExpression *);
+    QQmlBoundSignalExpression *expression() const;
+    QQmlBoundSignalExpression *setExpression(QQmlBoundSignalExpression *);
     QObject *object() { return m_owner; }
 
     bool isEvaluating() const { return m_isEvaluating; }
@@ -103,7 +140,7 @@ protected:
     virtual int qt_metacall(QMetaObject::Call c, int id, void **a);
 
 private:
-    QQmlExpression *m_expression;
+    QQmlBoundSignalExpression *m_expression;
     QMetaMethod m_signal;
     bool m_paramsValid : 1;
     bool m_isEvaluating : 1;
@@ -120,8 +157,8 @@ public:
 
     int index() const;
 
-    QQmlExpression *expression() const;
-    QQmlExpression *setExpression(QQmlExpression *);
+    QQmlBoundSignalExpression *expression() const;
+    QQmlBoundSignalExpression *setExpression(QQmlBoundSignalExpression *);
     QObject *object() { return m_owner; }
 
     static void subscriptionCallback(QQmlNotifierEndpoint *e);
@@ -129,7 +166,7 @@ public:
     bool isEvaluating() const { return m_isEvaluating; }
 
 private:
-    QQmlExpression *m_expression;
+    QQmlBoundSignalExpression *m_expression;
     QObject *m_owner;
     int m_index;
     bool m_isEvaluating;