add QMetaEnum usage for autogenerated code

Author: Oleksandr Kunichik

codegen/facelift/templates/Enum.template.h

@@ -74,37 +74,20 @@ template<> inline const std::initializer_list<{{enum.fullyQualifiedCppType}}>& v
     return values;
 }
 
-template <> inline QString enumToString(const {{enum.fullyQualifiedCppType}}& v)
-{
-    const char* s = "Invalid";
-    switch(v) {
-    {% for member in enum.members %}
-    case {{enum.fullyQualifiedCppType}}::{{member}}:
-        s = "{{member}}";
-        break;
-    {% endfor %}
-    default:
-        break;
-    }
-    return s;
-}
 
-}
+} // end namespace facelift
 
-
-inline void assignFromString(const QString &s, {{enum.fullyQualifiedCppType}}& v)
+inline void fromString(const QString& string, {{enum.fullyQualifiedCppType}}& value)
 {
-    {% for member in enum.members %}
-    if (s == "{{member}}")
-        v = {{enum.fullyQualifiedCppType}}::{{member}};
-    else
-    {% endfor %}
-        ::facelift::onAssignFromStringError(s);
+    auto valuePointer = facelift::Enum::fromString<{{enum.fullyQualifiedCppType}}>(string);
+    if(!valuePointer) {
+        facelift::Enum::fromStringError(string);
+    }
+    value = *valuePointer;
 }
 
-
-inline QTextStream &operator <<(QTextStream &outStream, const {{enum.fullyQualifiedCppType}}& f)
+inline QTextStream &operator <<(QTextStream& outStream, const {{enum.fullyQualifiedCppType}}& value)
 {
-    outStream << facelift::enumToString(f);
+    outStream << facelift::Enum::toString(value);
     return outStream;
 }

src/model/FaceliftCommon.h

@@ -66,15 +66,6 @@ inline const std::initializer_list<Type> &validValues()
     return l;
 }
 
-
-template<typename Type>
-QString enumToString(const Type &v)
-{
-    Q_UNUSED(v);
-    static_assert(!std::is_enum<Type>::value, "Missing specialization of enumToString() template");
-    return "";
-}
-
 #ifdef QT_DEBUG
 #define faceliftSeriousError qFatal
 #else

src/model/FaceliftEnum.cpp

@@ -32,10 +32,15 @@
 #include <QDebug>
 
 namespace facelift {
+    
+namespace Enum {
 
-void onAssignFromStringError(const QString &s)
+void fromStringError(const QString &string)
 {
-    qFatal("No enum value matching string %s", qPrintable(s));
+    qFatal("No enum value matching string %s", qPrintable(string));
 }
 
-}
+
+} // end namespace Enum
+
+} // end namespace facelift

src/model/FaceliftEnum.h

@@ -31,11 +31,41 @@
 #pragma once
 
 #include "FaceliftCommon.h"
-#include <QObject>
-#include <QTextStream>
+#include <type_traits>
+#include <memory>
+#include <QString>
+#include <QMetaEnum>
+#include <QByteArray>
 
 namespace facelift {
 
-void onAssignFromStringError(const QString &s);
+namespace Enum {
 
+void fromStringError(const QString &string);
+
+// Returns the string that is used as the name of the given enumeration value,
+// or an empty string if value is not defined
+template<class T, std::enable_if_t<QtPrivate::IsQEnumHelper<T>::Value, T>* = nullptr>
+QString toString(T value)
+{
+    return QMetaEnum::fromType<T>().valueToKey(static_cast<int>(value));
+}
+
+// Returns the enumaration value of the given enumeration key, or nullptr if key is not defined.
+// TODO change std::unique_ptr to std::optional when it will be possible
+template<typename T>
+std::unique_ptr<T> fromString(const QString &string)
+{
+    QByteArray byteArray = string.toLocal8Bit();
+    bool ok {};
+    int value = QMetaEnum::fromType<T>().keyToValue(byteArray.data(), &ok);
+    
+    T result = static_cast<T>(value);
+
+    return ok ? std::make_unique<T>(result) : nullptr;
 }
+
+
+} // end namespace Enum
+
+} // end namespace facelift

src/model/StringConversionHandler.h

@@ -37,18 +37,17 @@
 #include <QList>
 #include <type_traits>
 #include "FaceliftCommon.h"
+#include "FaceliftEnum.h"
 
 namespace facelift {
 
 class InterfaceBase;
 class StructureBase;
 
-template<typename Type, typename Enable = void>
+template<typename T, typename Enable = void>
 struct StringConversionHandler
 {
-    typedef Type QMLType;
-
-    static QString toString(const Type &v)
+    static QString toString(const T &v)
     {
         QString s;
         QTextStream(&s) << v;
@@ -65,77 +64,77 @@ struct StringConversionHandler<QVariant>
     }
 };
 
-QString qObjectToString(const QObject *o);
+QString qObjectToString(const QObject *object);
 
-template<typename Type>
-struct StringConversionHandler<Type *, typename std::enable_if<std::is_base_of<InterfaceBase, Type>::value>::type>
+template<typename T>
+struct StringConversionHandler<T*, std::enable_if_t<std::is_base_of<InterfaceBase, T>::value>>
 {
-    static QString toString(const Type *o)
+    static QString toString(const T *object)
     {
-        return qObjectToString(o);
+        return qObjectToString(object);
     }
 };
 
 
-template<typename Type>
-struct StringConversionHandler<Type, typename std::enable_if<std::is_base_of<StructureBase, Type>::value>::type>
+template<typename T>
+struct StringConversionHandler<T, std::enable_if_t<std::is_base_of<StructureBase, T>::value>>
 {
-    static QString toString(const Type &v)
+    static QString toString(const T &value)
     {
-        return v.toString();
+        return value.toString();
     }
 };
 
-
-template<typename Type>
-struct StringConversionHandler<Type, typename std::enable_if<std::is_enum<Type>::value>::type>
+template<typename T>
+struct StringConversionHandler<T, std::enable_if_t<QtPrivate::IsQEnumHelper<T>::Value, T>>
 {
-    static QString toString(const Type &v)
+    static QString toString(T value)
     {
-        return facelift::enumToString(v);
+        return Enum::toString(value);        
     }
 };
 
-template<typename ElementType>
-struct StringConversionHandler<QList<ElementType> >
+template<typename T>
+struct StringConversionHandler<QList<T> >
 {
-    static QString toString(const QList<ElementType> &v)
+    static QString toString(const QList<T> &v)
     {
         QString s;
         QTextStream str(&s);
         str << "[ ";
         for (const auto &element : v) {
-            str << StringConversionHandler<ElementType>::toString(element);
+            str << StringConversionHandler<T>::toString(element);
             str << ", ";
         }
         str << "]";
         return s;
     }
 };
 
-template<typename ElementType>
-struct StringConversionHandler<QMap<QString, ElementType> >
+template<typename T>
+struct StringConversionHandler<QMap<QString, T> >
 {
-    static QString toString(const QMap<QString, ElementType> &map)
+    static QString toString(const QMap<QString, T> &map)
     {
         QString s;
         QTextStream str(&s);
         str << "[ ";
         for (auto i = map.constBegin(); i != map.constEnd(); ++i) {
             str << StringConversionHandler<QString>::toString(i.key());
             str << ":";
-            str << StringConversionHandler<ElementType>::toString(i.value());
+            str << StringConversionHandler<T>::toString(i.value());
             str << ", ";
         }
         str << "]";
         return s;
     }
 };
 
-template<typename Type>
-inline QString toString(const Type &v)
+template<typename T>
+inline QString toString(const T &v)
 {
-    return StringConversionHandler<Type>::toString(v);
+    return StringConversionHandler<T>::toString(v);
 }
 
+
 }