Add initializer list support in QJsonObject.

It allows to create a QJsonObject instance in C++ by using
initializer list of pairs QString QJsonValue, for example:

QJsonObject o = {{"property1", 1}, {"property2", 2}};

[ChangeLog][QtCore][QtJson] QJsonObject now supports
C++11 initializer lists.

Task-number: QTBUG-26606
Change-Id: I67af881e175f427e563e685336c48a5f8466b476
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/json/qjsonobject.cpp

@@ -115,6 +115,20 @@ QJsonObject::QJsonObject()
 {
 }
 
+/*!
+    \fn QJsonObject::QJsonObject(std::initializer_list<QPair<QString, QJsonValue> > args)
+    \since 5.4
+    Constructs a QJsonObject instance initialized from \a args initialization list.
+    For example:
+    \code
+    QJsonObject object
+    {
+        {"property1", 1},
+        {"property2", 2}
+    };
+    \endcode
+*/
+
 /*!
     \internal
  */
@@ -126,6 +140,19 @@ QJsonObject::QJsonObject(QJsonPrivate::Data *data, QJsonPrivate::Object *object)
     d->ref.ref();
 }
 
+/*!
+    This method replaces part of the QJsonObject(std::initializer_list<QPair<QString, QJsonValue>> args) body.
+    The constructor needs to be inline, but we do not want to leak implementation details
+    of this class.
+    \note this method is called for an uninitialized object
+    \internal
+ */
+
+void QJsonObject::initialize()
+{
+    d = 0;
+    o = 0;
+}
 
 /*!
     Destroys the object.

src/corelib/json/qjsonobject.h

@@ -44,6 +44,10 @@
 
 #include <QtCore/qjsonvalue.h>
 #include <QtCore/qiterator.h>
+#ifdef Q_COMPILER_INITIALIZER_LISTS
+#include <QtCore/qpair.h>
+#include <initializer_list>
+#endif
 
 QT_BEGIN_NAMESPACE
 
@@ -55,6 +59,16 @@ class Q_CORE_EXPORT QJsonObject
 {
 public:
     QJsonObject();
+
+#if defined(Q_COMPILER_INITIALIZER_LISTS) || defined(Q_QDOC)
+    QJsonObject(std::initializer_list<QPair<QString, QJsonValue> > args)
+    {
+        initialize();
+        for (std::initializer_list<QPair<QString, QJsonValue> >::const_iterator i = args.begin(); i != args.end(); ++i)
+            insert(i->first, i->second);
+    }
+#endif
+
     ~QJsonObject();
 
     QJsonObject(const QJsonObject &other);
@@ -195,6 +209,7 @@ private:
     friend Q_CORE_EXPORT QDebug operator<<(QDebug, const QJsonObject &);
 
     QJsonObject(QJsonPrivate::Data *data, QJsonPrivate::Object *object);
+    void initialize();
     void detach(uint reserve = 0);
     void compact();
 

tests/auto/corelib/json/tst_qtjson.cpp

@@ -148,6 +148,7 @@ private Q_SLOTS:
     void longStrings();
 
     void arrayInitializerList();
+    void objectInitializerList();
 private:
     QString testDataDir;
 };
@@ -2681,22 +2682,72 @@ void tst_QtJson::arrayInitializerList()
         QCOMPARE(QJsonValue(a3[1]), QJsonValue(o));
         QCOMPARE(QJsonValue(a3[2]), QJsonValue(a2));
 
-        QJsonArray a4 { 1, QJsonArray{1,2,3}, QJsonArray{"hello", 2} };
+        QJsonArray a4 { 1, QJsonArray{1,2,3}, QJsonArray{"hello", 2}, QJsonObject{{"one", 1}} };
-        QCOMPARE(a4.count(), 3);
+        QCOMPARE(a4.count(), 4);
         QCOMPARE(QJsonValue(a4[0]), QJsonValue(1));
 
         {
             QJsonArray a41 = a4[1].toArray();
             QJsonArray a42 = a4[2].toArray();
+            QJsonObject a43 = a4[3].toObject();
             QCOMPARE(a41.count(), 3);
             QCOMPARE(a42.count(), 2);
+            QCOMPARE(a43.count(), 1);
 
             QCOMPARE(QJsonValue(a41[2]), QJsonValue(3));
             QCOMPARE(QJsonValue(a42[1]), QJsonValue(2));
+            QCOMPARE(QJsonValue(a43["one"]), QJsonValue(1));
         }
     }
 #endif
 }
 
+void tst_QtJson::objectInitializerList()
+{
+#ifndef Q_COMPILER_INITIALIZER_LISTS
+    QSKIP("initializer_list is enabled only with c++11 support");
+#else
+    QVERIFY(QJsonObject{}.isEmpty());
+
+    {   // one property
+        QJsonObject one {{"one", 1}};
+        QCOMPARE(one.count(), 1);
+        QVERIFY(one.contains("one"));
+        QCOMPARE(QJsonValue(one["one"]), QJsonValue(1));
+    }
+    {   // two properties
+        QJsonObject two {
+                           {"one", 1},
+                           {"two", 2}
+                        };
+        QCOMPARE(two.count(), 2);
+        QVERIFY(two.contains("one"));
+        QVERIFY(two.contains("two"));
+        QCOMPARE(QJsonValue(two["one"]), QJsonValue(1));
+        QCOMPARE(QJsonValue(two["two"]), QJsonValue(2));
+    }
+    {   // nested object
+        QJsonObject object{{"nested", QJsonObject{{"innerProperty", 2}}}};
+        QCOMPARE(object.count(), 1);
+        QVERIFY(object.contains("nested"));
+        QVERIFY(object["nested"].isObject());
+
+        QJsonObject nested = object["nested"].toObject();
+        QCOMPARE(QJsonValue(nested["innerProperty"]), QJsonValue(2));
+    }
+    {   // nested array
+        QJsonObject object{{"nested", QJsonArray{"innerValue", 2.1, "bum cyk cyk"}}};
+        QCOMPARE(object.count(), 1);
+        QVERIFY(object.contains("nested"));
+        QVERIFY(object["nested"].isArray());
+
+        QJsonArray nested = object["nested"].toArray();
+        QCOMPARE(nested.count(), 3);
+        QCOMPARE(QJsonValue(nested[0]), QJsonValue("innerValue"));
+        QCOMPARE(QJsonValue(nested[1]), QJsonValue(2.1));
+    }
+#endif
+}
+
 QTEST_MAIN(tst_QtJson)
 #include "tst_qtjson.moc"