Provide a way of exposing private QProperties with a fake API

The API reduces the amount of manual plumbing required to offer a
conceptual property through the traditional setter/getter API as well as
through QProperty<T> API. Since the latter would require inlining the
type and thus making it impossible to add new properties without
breaking binary compatibility, this patch introduces a fake API that
behaves similar but does not contain the property by value.

Change-Id: Ib9bccd867f0e4e36a520e5583ba348e728284253
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

7 files changed, 223 insertions, 36 deletions

diff --git a/src/tools/moc/generator.cpp b/src/tools/moc/generator.cpp
index acb7cdffe9..976d49ad20 100644
--- a/src/tools/moc/generator.cpp
+++ b/src/tools/moc/generator.cpp
@@ -616,6 +616,11 @@ void Generator::generateCode()
         generateSignal(&cdef->signalList[signalindex], signalindex);
 
 //
+// Generate QProperty forwarding API
+//
+    generateQPropertyApi();
+
+//
 // Generate plugin meta data
 //
     generatePluginMetaData();
@@ -1621,6 +1626,106 @@ void Generator::generateSignal(FunctionDef *def,int index)
     fprintf(out, "}\n");
 }
 
+void Generator::generateQPropertyApi()
+{
+    for (const PrivateQPropertyDef &property: cdef->privateQProperties) {
+        auto printAccessor = [this, property](bool constAccessor = false) {
+            const char *constOrNot = constAccessor ? "const " : " ";
+            fprintf(out, "    const size_t propertyMemberOffset = reinterpret_cast<size_t>(&(static_cast<%s *>(nullptr)->%s));\n", cdef->qualified.constData(), property.name.constData());
+            fprintf(out, "    %sauto *thisPtr = reinterpret_cast<%s%s *>(reinterpret_cast<%schar *>(this) - propertyMemberOffset);\n", constOrNot, constOrNot, cdef->qualified.constData(), constOrNot);
+        };
+
+        // property accessor
+        fprintf(out, "\n%s %s::_qt_property_api_%s::value() const\n{\n",
+                property.type.name.constData(),
+                cdef->qualified.constData(),
+                property.name.constData());
+        printAccessor(/*const*/true);
+        fprintf(out, "    return thisPtr->%s->%s.value();\n", property.accessor.constData(), property.name.constData());
+        fprintf(out, "}\n");
+
+        // property value setter
+        fprintf(out, "\nvoid %s::_qt_property_api_%s::setValue(const %s &value)\n{\n",
+                cdef->qualified.constData(),
+                property.name.constData(),
+                property.type.name.constData());
+        printAccessor();
+        fprintf(out, "    return thisPtr->%s->%s.setValue(value);\n", property.accessor.constData(), property.name.constData());
+        fprintf(out, "}\n");
+
+        // property value move setter
+        fprintf(out, "\nvoid %s::_qt_property_api_%s::setValue(%s &&value)\n{\n",
+                cdef->qualified.constData(),
+                property.name.constData(),
+                property.type.name.constData());
+        printAccessor();
+        fprintf(out, "    return thisPtr->%s->%s.setValue(std::move(value));\n", property.accessor.constData(), property.name.constData());
+        fprintf(out, "}\n");
+
+        // binding setter
+        fprintf(out, "\nQPropertyBinding<%s> %s::_qt_property_api_%s::setBinding(const QPropertyBinding<%s> &binding)\n{\n",
+                property.type.name.constData(),
+                cdef->qualified.constData(),
+                property.name.constData(),
+                property.type.name.constData());
+        printAccessor();
+        fprintf(out, "    return thisPtr->%s->%s.setBinding(binding);\n", property.accessor.constData(), property.name.constData());
+        fprintf(out, "}\n");
+
+        // binding move setter
+        fprintf(out, "\nQPropertyBinding<%s> %s::_qt_property_api_%s::setBinding(QPropertyBinding<%s> &&binding)\n{\n",
+                property.type.name.constData(),
+                cdef->qualified.constData(),
+                property.name.constData(),
+                property.type.name.constData());
+        printAccessor();
+        fprintf(out, "    return thisPtr->%s->%s.setBinding(std::move(binding));\n", property.accessor.constData(), property.name.constData());
+        fprintf(out, "}\n");
+
+        // untyped binding setter
+        fprintf(out, "\nbool %s::_qt_property_api_%s::setBinding(const QUntypedPropertyBinding &binding)\n{\n",
+                cdef->qualified.constData(),
+                property.name.constData());
+        printAccessor();
+        fprintf(out, "    return thisPtr->%s->%s.setBinding(binding);\n", property.accessor.constData(), property.name.constData());
+        fprintf(out, "}\n");
+
+        // binding bool getter
+        fprintf(out, "\nbool %s::_qt_property_api_%s::hasBinding() const\n{\n",
+                cdef->qualified.constData(),
+                property.name.constData());
+        printAccessor(/*const*/true);
+        fprintf(out, "    return thisPtr->%s->%s.hasBinding();\n", property.accessor.constData(), property.name.constData());
+        fprintf(out, "}\n");
+
+        // binding getter
+        fprintf(out, "\nQPropertyBinding<%s> %s::_qt_property_api_%s::binding() const\n{\n",
+                property.type.name.constData(),
+                cdef->qualified.constData(),
+                property.name.constData());
+        printAccessor(/*const*/true);
+        fprintf(out, "    return thisPtr->%s->%s.binding();\n", property.accessor.constData(), property.name.constData());
+        fprintf(out, "}\n");
+
+        // binding taker
+        fprintf(out, "\nQPropertyBinding<%s> %s::_qt_property_api_%s::takeBinding()\n{\n",
+                property.type.name.constData(),
+                cdef->qualified.constData(),
+                property.name.constData());
+        printAccessor();
+        fprintf(out, "    return thisPtr->%s->%s.takeBinding();\n", property.accessor.constData(), property.name.constData());
+        fprintf(out, "}\n");
+
+        // property setter function
+        fprintf(out, "\nvoid %s::%s(const %s &value)\n{\n",
+                cdef->qualified.constData(),
+                property.setter.constData(),
+                property.type.name.constData());
+        fprintf(out, "    %s->%s.setValue(value);\n", property.accessor.constData(), property.name.constData());
+        fprintf(out, "}\n\n");
+    }
+}
+
 static CborError jsonValueToCbor(CborEncoder *parent, const QJsonValue &v);
 static CborError jsonObjectToCbor(CborEncoder *parent, const QJsonObject &o)
 {
diff --git a/src/tools/moc/generator.h b/src/tools/moc/generator.h
index eae0353199..e92b9d1208 100644
--- a/src/tools/moc/generator.h
+++ b/src/tools/moc/generator.h
@@ -58,6 +58,7 @@ private:
     void generateMetacall();
     void generateStaticMetacall();
     void generateSignal(FunctionDef *def, int index);
+    void generateQPropertyApi();
     void generatePluginMetaData();
     QMultiMap<QByteArray, int> automaticPropertyMetaTypesHelper();
     QMap<int, QMultiMap<QByteArray, int> > methodsWithAutomaticTypesHelper(const QVector<FunctionDef> &methodList);
diff --git a/src/tools/moc/keywords.cpp b/src/tools/moc/keywords.cpp
index cc7d747f5b..6a56d2cea5 100644
--- a/src/tools/moc/keywords.cpp
+++ b/src/tools/moc/keywords.cpp
@@ -30,12 +30,12 @@
 // DO NOT EDIT.
 
 static const short keyword_trans[][128] = {
-    {0,0,0,0,0,0,0,0,0,579,576,0,0,0,0,0,
+    {0,0,0,0,0,0,0,0,0,588,585,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
-     579,252,577,580,8,38,239,578,25,26,236,234,30,235,27,237,
+     588,252,586,589,8,38,239,587,25,26,236,234,30,235,27,237,
      22,22,22,22,22,22,22,22,22,22,34,41,23,39,24,43,
      0,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
-     8,21,8,8,8,8,8,8,8,8,8,31,582,32,238,8,
+     8,21,8,8,8,8,8,8,8,8,8,31,591,32,238,8,
      0,1,2,3,4,5,6,7,8,9,8,8,10,11,12,13,
      14,8,15,16,17,18,19,20,8,8,8,36,245,37,248,0},
     {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
@@ -177,7 +177,7 @@ static const short keyword_trans[][128] = {
     {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,42,0,0,0,28,0,
-     585,585,585,585,585,585,585,585,585,585,0,0,0,0,0,0,
+     594,594,594,594,594,594,594,594,594,594,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
@@ -336,7 +336,7 @@ static const short keyword_trans[][128] = {
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
     {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
-     0,0,0,0,0,0,0,0,0,0,584,0,0,0,0,583,
+     0,0,0,0,0,0,0,0,0,0,593,0,0,0,0,592,
      0,0,0,0,0,0,0,0,0,0,0,0,0,258,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
@@ -378,8 +378,8 @@ static const short keyword_trans[][128] = {
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
-     0,0,0,475,424,408,416,380,0,484,0,0,0,565,364,358,
-     386,0,557,472,0,0,0,0,0,0,0,0,0,0,0,0,
+     0,0,0,475,424,408,416,380,0,484,0,0,0,574,364,358,
+     386,0,566,472,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
     {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
@@ -443,7 +443,7 @@ static const short keyword_trans[][128] = {
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
-     549,0,0,517,0,0,0,0,0,0,0,0,0,0,0,0,
+     549,557,0,517,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
      0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
 };
@@ -1013,30 +1013,39 @@ static const struct
     {CHARACTER, 0, 84, 555, CHARACTER},
     {CHARACTER, 0, 89, 556, CHARACTER},
     {Q_PRIVATE_PROPERTY_TOKEN, 0, 0, 0, CHARACTER},
-    {CHARACTER, 0, 69, 558, CHARACTER},
-    {CHARACTER, 0, 86, 559, CHARACTER},
-    {CHARACTER, 0, 73, 560, CHARACTER},
-    {CHARACTER, 0, 83, 561, CHARACTER},
-    {CHARACTER, 0, 73, 562, CHARACTER},
-    {CHARACTER, 0, 79, 563, CHARACTER},
-    {CHARACTER, 0, 78, 564, CHARACTER},
-    {Q_REVISION_TOKEN, 0, 0, 0, CHARACTER},
-    {CHARACTER, 0, 79, 566, CHARACTER},
-    {CHARACTER, 0, 67, 567, CHARACTER},
-    {CHARACTER, 0, 95, 568, CHARACTER},
+    {CHARACTER, 0, 80, 558, CHARACTER},
+    {CHARACTER, 0, 82, 559, CHARACTER},
+    {CHARACTER, 0, 79, 560, CHARACTER},
+    {CHARACTER, 0, 80, 561, CHARACTER},
+    {CHARACTER, 0, 69, 562, CHARACTER},
+    {CHARACTER, 0, 82, 563, CHARACTER},
+    {CHARACTER, 0, 84, 564, CHARACTER},
+    {CHARACTER, 0, 89, 565, CHARACTER},
+    {Q_PRIVATE_QPROPERTY_TOKEN, 0, 0, 0, CHARACTER},
+    {CHARACTER, 0, 69, 567, CHARACTER},
+    {CHARACTER, 0, 86, 568, CHARACTER},
     {CHARACTER, 0, 73, 569, CHARACTER},
-    {CHARACTER, 0, 78, 570, CHARACTER},
-    {CHARACTER, 0, 67, 571, CHARACTER},
-    {CHARACTER, 0, 76, 572, CHARACTER},
-    {CHARACTER, 0, 85, 573, CHARACTER},
-    {CHARACTER, 0, 68, 574, CHARACTER},
-    {CHARACTER, 0, 69, 575, CHARACTER},
+    {CHARACTER, 0, 83, 570, CHARACTER},
+    {CHARACTER, 0, 73, 571, CHARACTER},
+    {CHARACTER, 0, 79, 572, CHARACTER},
+    {CHARACTER, 0, 78, 573, CHARACTER},
+    {Q_REVISION_TOKEN, 0, 0, 0, CHARACTER},
+    {CHARACTER, 0, 79, 575, CHARACTER},
+    {CHARACTER, 0, 67, 576, CHARACTER},
+    {CHARACTER, 0, 95, 577, CHARACTER},
+    {CHARACTER, 0, 73, 578, CHARACTER},
+    {CHARACTER, 0, 78, 579, CHARACTER},
+    {CHARACTER, 0, 67, 580, CHARACTER},
+    {CHARACTER, 0, 76, 581, CHARACTER},
+    {CHARACTER, 0, 85, 582, CHARACTER},
+    {CHARACTER, 0, 68, 583, CHARACTER},
+    {CHARACTER, 0, 69, 584, CHARACTER},
     {Q_MOC_INCLUDE_TOKEN, 0, 0, 0, CHARACTER},
     {NEWLINE, 0, 0, 0, NOTOKEN},
     {QUOTE, 0, 0, 0, NOTOKEN},
     {SINGLEQUOTE, 0, 0, 0, NOTOKEN},
     {WHITESPACE, 0, 0, 0, NOTOKEN},
-    {HASH, 0, 35, 581, HASH},
+    {HASH, 0, 35, 590, HASH},
     {PP_HASHHASH, 0, 0, 0, NOTOKEN},
     {BACKSLASH, 0, 0, 0, NOTOKEN},
     {CPP_COMMENT, 0, 0, 0, NOTOKEN},
diff --git a/src/tools/moc/moc.cpp b/src/tools/moc/moc.cpp
index 2444d0db90..949a2e075a 100644
--- a/src/tools/moc/moc.cpp
+++ b/src/tools/moc/moc.cpp
@@ -878,6 +878,9 @@ void Moc::parse()
                 case Q_PRIVATE_PROPERTY_TOKEN:
                     parsePrivateProperty(&def);
                     break;
+                case Q_PRIVATE_QPROPERTY_TOKEN:
+                    parsePrivateQProperty(&def);
+                    break;
                 case ENUM: {
                     EnumDef enumDef;
                     if (parseEnum(&enumDef))
@@ -1031,10 +1034,14 @@ static QByteArrayList requiredQtContainers(const QVector<ClassDef> &classes)
     QByteArrayList required;
     required.reserve(candidates.size());
 
+    bool needsQProperty = false;
+
     for (const auto &candidate : candidates) {
         const QByteArray pattern = candidate + '<';
 
         for (const auto &c : classes) {
+            if (!c.privateQProperties.isEmpty())
+                needsQProperty = true;
             if (any_type_contains(c.propertyList, pattern) ||
                     any_arg_contains(c.slotList, pattern) ||
                     any_arg_contains(c.signalList, pattern) ||
@@ -1045,6 +1052,9 @@ static QByteArrayList requiredQtContainers(const QVector<ClassDef> &classes)
         }
     }
 
+    if (needsQProperty)
+        required.push_back("QProperty");
+
     return required;
 }
 
@@ -1268,6 +1278,14 @@ void Moc::createPropertyDef(PropertyDef &propDef)
 
     propDef.type = type;
 
+    next();
+    propDef.name = lexem();
+
+    parsePropertyAttributes(propDef);
+}
+
+void Moc::parsePropertyAttributes(PropertyDef &propDef)
+{
     auto checkIsFunction = [&](const QByteArray &def, const char *name) {
         if (def.endsWith(')')) {
             QByteArray msg = "Providing a function for ";
@@ -1277,9 +1295,6 @@ void Moc::createPropertyDef(PropertyDef &propDef)
         }
     };
 
-    next();
-    propDef.name = lexem();
-
     while (test(IDENTIFIER)) {
         const QByteArray l = lexem();
         if (l[0] == 'C' && l == "CONSTANT") {
@@ -1459,23 +1474,30 @@ void Moc::parsePluginData(ClassDef *def)
     next(RPAREN);
 }
 
-void Moc::parsePrivateProperty(ClassDef *def)
+QByteArray Moc::parsePropertyAccessor()
 {
-    next(LPAREN);
-    PropertyDef propDef;
     next(IDENTIFIER);
-    propDef.inPrivateClass = lexem();
+    QByteArray accessor = lexem();
     while (test(SCOPE)) {
-        propDef.inPrivateClass += lexem();
+        accessor += lexem();
         next(IDENTIFIER);
-        propDef.inPrivateClass += lexem();
+        accessor += lexem();
     }
     // also allow void functions
     if (test(LPAREN)) {
         next(RPAREN);
-        propDef.inPrivateClass += "()";
+        accessor += "()";
     }
 
+    return accessor;
+}
+
+void Moc::parsePrivateProperty(ClassDef *def)
+{
+    next(LPAREN);
+    PropertyDef propDef;
+    propDef.inPrivateClass = parsePropertyAccessor();
+
     next(COMMA);
 
     createPropertyDef(propDef);
@@ -1488,6 +1510,42 @@ void Moc::parsePrivateProperty(ClassDef *def)
     def->propertyList += propDef;
 }
 
+void Moc::parsePrivateQProperty(ClassDef *def)
+{
+    next(LPAREN);
+    const QByteArray accessor = parsePropertyAccessor();
+    next(COMMA);
+    const Type type = parseType();
+    next(COMMA);
+    next(IDENTIFIER);
+    const QByteArray name = lexem();
+    next(COMMA);
+    next(IDENTIFIER);
+    const QByteArray setter = lexem();
+
+    def->privateQProperties += PrivateQPropertyDef{type, name, setter, accessor};
+
+    PropertyDef propDef;
+    propDef.name = name;
+    propDef.type = type.name;
+    propDef.read = name + ".value";
+    propDef.write = name + ".setValue";
+    propDef.isQProperty = true;
+    propDef.inPrivateClass = accessor;
+    propDef.designable = propDef.scriptable = propDef.stored = "true";
+    propDef.user = "false";
+
+    if (test(COMMA))
+        parsePropertyAttributes(propDef);
+
+    next(RPAREN);
+
+    if (!propDef.notify.isEmpty())
+        def->notifyableProperties++;
+
+    def->propertyList += propDef;
+}
+
 void Moc::parseEnumOrFlag(BaseDef *def, bool isFlag)
 {
     next(LPAREN);
diff --git a/src/tools/moc/moc.h b/src/tools/moc/moc.h
index 210b6c7c2a..486d033049 100644
--- a/src/tools/moc/moc.h
+++ b/src/tools/moc/moc.h
@@ -148,6 +148,14 @@ struct PropertyDef
 };
 Q_DECLARE_TYPEINFO(PropertyDef, Q_MOVABLE_TYPE);
 
+struct PrivateQPropertyDef
+{
+    Type type;
+    QByteArray name;
+    QByteArray setter;
+    QByteArray accessor;
+};
+Q_DECLARE_TYPEINFO(PrivateQPropertyDef, Q_MOVABLE_TYPE);
 
 struct ClassInfoDef
 {
@@ -191,6 +199,7 @@ struct ClassDef : BaseDef {
     QVector<FunctionDef> signalList, slotList, methodList, publicList;
     QVector<QByteArray> nonClassSignalList;
     QVector<PropertyDef> propertyList;
+    QVector<PrivateQPropertyDef> privateQProperties;
     QSet<QByteArray> qPropertyMembers;
     int notifyableProperties = 0;
     int revisionedMethods = 0;
@@ -258,6 +267,7 @@ public:
     void parseProperty(ClassDef *def);
     void parsePluginData(ClassDef *def);
     void createPropertyDef(PropertyDef &def);
+    void parsePropertyAttributes(PropertyDef &propDef);
     void parseEnumOrFlag(BaseDef *def, bool isFlag);
     void parseFlag(BaseDef *def);
     void parseClassInfo(BaseDef *def);
@@ -266,7 +276,9 @@ public:
     void parseDeclareMetatype();
     void parseMocInclude();
     void parseSlotInPrivate(ClassDef *def, FunctionDef::Access access);
+    QByteArray parsePropertyAccessor();
     void parsePrivateProperty(ClassDef *def);
+    void parsePrivateQProperty(ClassDef *def);
 
     void parseFunctionArguments(FunctionDef *def);
 
diff --git a/src/tools/moc/token.h b/src/tools/moc/token.h
index c11ec6a38c..0b6e9c4f7c 100644
--- a/src/tools/moc/token.h
+++ b/src/tools/moc/token.h
@@ -178,6 +178,7 @@ QT_BEGIN_NAMESPACE
     F(Q_INVOKABLE_TOKEN) \
     F(Q_SCRIPTABLE_TOKEN) \
     F(Q_PRIVATE_PROPERTY_TOKEN) \
+    F(Q_PRIVATE_QPROPERTY_TOKEN) \
     F(Q_REVISION_TOKEN) \
     F(Q_MOC_INCLUDE_TOKEN) \
     F(SPECIAL_TREATMENT_MARK) \
diff --git a/src/tools/moc/util/generate_keywords.cpp b/src/tools/moc/util/generate_keywords.cpp
index c2cfe37fab..02a36c5000 100644
--- a/src/tools/moc/util/generate_keywords.cpp
+++ b/src/tools/moc/util/generate_keywords.cpp
@@ -242,6 +242,7 @@ static const Keyword keywords[] = {
     { "Q_SLOT", "Q_SLOT_TOKEN" },
     { "Q_SCRIPTABLE", "Q_SCRIPTABLE_TOKEN" },
     { "Q_PRIVATE_PROPERTY", "Q_PRIVATE_PROPERTY_TOKEN" },
+    { "Q_PRIVATE_QPROPERTY", "Q_PRIVATE_QPROPERTY_TOKEN" },
     { "Q_REVISION", "Q_REVISION_TOKEN" },
     { "Q_MOC_INCLUDE", "Q_MOC_INCLUDE_TOKEN" },
     { "\n", "NEWLINE" },