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, 15 insertions, 0 deletions

diff --git a/src/qml/qml/qqmlrewrite.cpp b/src/qml/qml/qqmlrewrite.cpp
index 72bd23955b..0bd8597ec4 100644
--- a/src/qml/qml/qqmlrewrite.cpp
+++ b/src/qml/qml/qqmlrewrite.cpp
@@ -419,6 +419,21 @@ QString RewriteSignalHandler::operator()(QQmlJS::AST::Node *node, const QString
     return rewritten;
 }
 
+QString RewriteSignalHandler::operator()(const QString &code, const QString &name, bool *ok)
+{
+    Engine engine;
+    Lexer lexer(&engine);
+    Parser parser(&engine);
+    lexer.setCode(code, 0);
+    parser.parseStatement();
+    if (!parser.statement()) {
+        if (ok) *ok = false;
+        return QString();
+    }
+    if (ok) *ok = true;
+    return operator()(parser.statement(), code, name);
+}
+
 } // namespace QQmlRewrite
 
 QT_END_NAMESPACE