Replace the special treatment of java::lang::String with a conversion trait

This extends the specialization of the property wrappers to anything we
have a matching native type for, including application custom types.

autotests/jnisignaturetest.cpp

@@ -6,6 +6,7 @@
 
 #include <kandroidextras/androidtypes.h>
 #include <kandroidextras/jnisignature.h>
+#include <kandroidextras/javatypes.h>
 
 #include <QtTest/qtest.h>
 

src/kandroidextras/android/intent.h

@@ -11,6 +11,7 @@
 
 #include <KAndroidExtras/AndroidTypes>
 #include <KAndroidExtras/JniProperty>
+#include <KAndroidExtras/JavaTypes>
 
 #include <QAndroidJniObject>
 

src/kandroidextras/android/manifestpermission.h

@@ -9,6 +9,7 @@
 
 #include <KAndroidExtras/AndroidTypes>
 #include <KAndroidExtras/JniProperty>
+#include <KAndroidExtras/JavaTypes>
 
 namespace KAndroidExtras {
 

src/kandroidextras/android/openablecolumns.h

@@ -9,6 +9,7 @@
 
 #include <KAndroidExtras/AndroidTypes>
 #include <KAndroidExtras/JniProperty>
+#include <KAndroidExtras/JavaTypes>
 
 namespace KAndroidExtras {
 

src/kandroidextras/android/uri.cpp

@@ -8,6 +8,7 @@
 
 #include <KAndroidExtras/AndroidTypes>
 #include <KAndroidExtras/JniSignature>
+#include <KAndroidExtras/JavaTypes>
 
 #include <QAndroidJniObject>
 #include <QUrl>

src/kandroidextras/java/javatypes.h

@@ -8,12 +8,25 @@
 #define KANDROIDEXTRAS_JAVATYPES_H
 
 #include <KAndroidExtras/JniTypes>
+#include <KAndroidExtras/JniTypeTraits>
 
 namespace KAndroidExtras {
 
 JNI_TYPE(java, io, File)
+JNI_TYPE(java, lang, String)
 JNI_TYPE(java, util, Locale)
 
+namespace Jni {
+template <> struct converter<QString> {
+    typedef java::lang::String type;
+    static inline QAndroidJniObject convert(const QString &value) { return QAndroidJniObject::fromString(value); }
+};
+template <> struct converter<java::lang::String> {
+    typedef QString type;
+    static inline QString convert(const QAndroidJniObject &value) { return value.toString(); }
+};
+}
+
 }
 
 #endif // KANDROIDEXTRAS_JAVATYPES_H

src/kandroidextras/jni/jniproperty.h

@@ -40,21 +40,17 @@ private: \
 template <typename PropType, typename ClassType, typename NameHolder, bool BasicType> struct StaticProperty {};
 template <typename PropType, typename ClassType, typename NameHolder>
 struct StaticProperty<PropType, ClassType, NameHolder, false> {
-    inline operator QAndroidJniObject() const
+    inline QAndroidJniObject get() const
     {
         return QAndroidJniObject::getStaticObjectField(Jni::typeName<ClassType>(), Jni::typeName<NameHolder>(), Jni::signature<PropType>());
     }
-};
-
-template <typename ClassType, typename NameHolder>
-struct StaticProperty<java::lang::String, ClassType, NameHolder, false> {
     inline operator QAndroidJniObject() const
     {
-        return QAndroidJniObject::getStaticObjectField(Jni::typeName<ClassType>(), Jni::typeName<NameHolder>(), Jni::signature<java::lang::String>());
+        return get();
     }
-    inline operator QString() const
+    inline operator typename Jni::converter<PropType>::type() const
     {
-        return QAndroidJniObject::getStaticObjectField(Jni::typeName<ClassType>(), Jni::typeName<NameHolder>(), Jni::signature<java::lang::String>()).toString();
+        return Jni::converter<PropType>::convert(get());
     }
 };
 
@@ -80,37 +76,30 @@ protected:
 template <typename PropType, typename ClassType, typename NameHolder, typename OffsetHolder, bool BasicType> struct Property {};
 template <typename PropType, typename ClassType, typename NameHolder, typename OffsetHolder>
 class Property<PropType, ClassType, NameHolder, OffsetHolder, false> : public PropertyBase<ClassType, OffsetHolder> {
+private:
+    struct _jni_NoType {};
 public:
-    inline operator QAndroidJniObject() const
+    inline QAndroidJniObject get() const
     {
         return this->handle().getObjectField(Jni::typeName<NameHolder>(), Jni::signature<PropType>());
     }
-    inline Property& operator=(const QAndroidJniObject &value)
-    {
-        this->handle().setField(Jni::typeName<NameHolder>(), Jni::signature<PropType>(), value.object());
-        return *this;
-    }
-};
-
-template <typename ClassType, typename NameHolder, typename OffsetHolder>
-class Property<java::lang::String, ClassType, NameHolder, OffsetHolder, false> : public PropertyBase<ClassType, OffsetHolder> {
-public:
     inline operator QAndroidJniObject() const
     {
-        return this->handle().getObjectField(Jni::typeName<NameHolder>(), Jni::signature<java::lang::String>());
+        return get();
     }
-    inline operator QString() const
+    inline operator typename Jni::converter<PropType>::type() const
     {
-        return this->handle().getObjectField(Jni::typeName<NameHolder>(), Jni::signature<java::lang::String>()).toString();
+        return Jni::converter<PropType>::convert(get());
     }
+
     inline Property& operator=(const QAndroidJniObject &value)
     {
-        this->handle().setField(Jni::typeName<NameHolder>(), Jni::signature<java::lang::String>(), value.object());
+        this->handle().setField(Jni::typeName<NameHolder>(), Jni::signature<PropType>(), value.object());
         return *this;
     }
-    inline Property& operator=(const QString &value)
+    inline Property& operator=(const typename std::conditional<std::is_same_v<typename Jni::converter<PropType>::type, void>, _jni_NoType, typename Jni::converter<PropType>::type>::type &value)
     {
-        this->handle().setField(Jni::typeName<NameHolder>(), Jni::signature<java::lang::String>(), QAndroidJniObject::fromString(value).object());
+        this->handle().setField(Jni::typeName<NameHolder>(), Jni::signature<PropType>(), Jni::reverse_converter<PropType>::type::convert(value).object());
         return *this;
     }
 };

src/kandroidextras/jni/jnitypes.h

@@ -61,9 +61,6 @@ namespace KAndroidExtras {
 /** Macro to define a nested Java class with its corresponding JNI signature string. */
 #define JNI_NESTED_TYPE(...) JNI_NESTED_TYPE_(PP_NARG(__VA_ARGS__), "", __VA_ARGS__)
 
-// defined here rather than as part of the java.* bindings as this is de-facto a basic built-in type
-JNI_TYPE(java, lang, String)
-
 namespace Jni
 {
     /** Returns the JNI type name of the given template argument. */

src/kandroidextras/jni/jnitypetraits.h

@@ -7,6 +7,8 @@
 #ifndef KANDROIDEXTRAS_JNITYPETRAITS_H
 #define KANDROIDEXTRAS_JNITYPETRAITS_H
 
+#include "jnitypes.h"
+
 #include <QAndroidJniObject>
 
 #include <type_traits>
@@ -28,6 +30,15 @@ template <> struct is_basic_type<jlong> : std::true_type {};
 template <> struct is_basic_type<jfloat> : std::true_type {};
 template <> struct is_basic_type<jdouble> : std::true_type {};
 
+
+template <typename T> struct converter {
+    typedef void type;
+};
+
+template <typename T> struct reverse_converter {
+    typedef converter<typename converter<T>::type> type;
+};
+
 }
 
 }