Add initializer list support in QJsonArray

It allows to create a QJsonArray instance in C++ by using
a similar expression to JSON. For example:

QJsonArray a = {1, 2, 4};

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

Task-number: QTBUG-26606
Change-Id: Icc352e518d9649d24176c89e7113d200d5c50b0d
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/json/qjsonarray.cpp

@@ -137,6 +137,18 @@ QJsonArray::QJsonArray()
 {
 }
 
+/*!
+    \fn QJsonArray::QJsonArray(std::initializer_list<QJsonValue> args)
+    \since 5.4
+    Creates an array initialized from \a args initialization list.
+
+    QJsonArray can be constructed in a way similar to JSON notation,
+    for example:
+    \code
+    QJsonArray array = { 1, 2.2, QString() };
+    \endcode
+ */
+
 /*!
     \internal
  */
@@ -148,6 +160,19 @@ QJsonArray::QJsonArray(QJsonPrivate::Data *data, QJsonPrivate::Array *array)
     d->ref.ref();
 }
 
+/*!
+    This method replaces part of QJsonArray(std::initializer_list<QJsonValue> args) .
+    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 QJsonArray::initialize()
+{
+    d = 0;
+    a = 0;
+}
+
 /*!
     Deletes the array.
  */

src/corelib/json/qjsonarray.h

@@ -44,6 +44,9 @@
 
 #include <QtCore/qjsonvalue.h>
 #include <QtCore/qiterator.h>
+#if defined(Q_COMPILER_INITIALIZER_LISTS)
+#include <initializer_list>
+#endif
 
 QT_BEGIN_NAMESPACE
 
@@ -56,6 +59,16 @@ class Q_CORE_EXPORT QJsonArray
 {
 public:
     QJsonArray();
+
+#if defined(Q_COMPILER_INITIALIZER_LISTS) || defined(Q_QDOC)
+    QJsonArray(std::initializer_list<QJsonValue> args)
+    {
+        initialize();
+        for (std::initializer_list<QJsonValue>::const_iterator i = args.begin(); i != args.end(); ++i)
+            append(*i);
+    }
+#endif
+
     ~QJsonArray();
 
     QJsonArray(const QJsonArray &other);
@@ -212,6 +225,7 @@ private:
     friend Q_CORE_EXPORT QDebug operator<<(QDebug, const QJsonArray &);
 
     QJsonArray(QJsonPrivate::Data *data, QJsonPrivate::Array *array);
+    void initialize();
     void compact();
     void detach(uint reserve = 0);
 

tests/auto/corelib/json/tst_qtjson.cpp

@@ -140,6 +140,8 @@ private Q_SLOTS:
     void nesting();
 
     void longStrings();
+
+    void arrayInitializerList();
 private:
     QString testDataDir;
 };
@@ -2443,5 +2445,55 @@ void tst_QtJson::testJsonValueRefDefault()
     QCOMPARE(empty["n/a"].toDouble(42.0), 42.0);
 }
 
+void tst_QtJson::arrayInitializerList()
+{
+#ifndef Q_COMPILER_INITIALIZER_LISTS
+    QSKIP("initializer_list is enabled only with c++11 support");
+#else
+    QVERIFY(QJsonArray{}.isEmpty());
+    QCOMPARE(QJsonArray{"one"}.count(), 1);
+    QCOMPARE(QJsonArray{1}.count(), 1);
+
+    {
+        QJsonArray a{1.3, "hello", 0};
+        QCOMPARE(QJsonValue(a[0]), QJsonValue(1.3));
+        QCOMPARE(QJsonValue(a[1]), QJsonValue("hello"));
+        QCOMPARE(QJsonValue(a[2]), QJsonValue(0));
+        QCOMPARE(a.count(), 3);
+    }
+    {
+        QJsonObject o;
+        o["property"] = 1;
+        QJsonArray a1 {o};
+        QCOMPARE(a1.count(), 1);
+        QCOMPARE(a1[0].toObject(), o);
+
+        QJsonArray a2 {o, 23};
+        QCOMPARE(a2.count(), 2);
+        QCOMPARE(a2[0].toObject(), o);
+        QCOMPARE(QJsonValue(a2[1]), QJsonValue(23));
+
+        QJsonArray a3 { a1, o, a2 };
+        QCOMPARE(QJsonValue(a3[0]), QJsonValue(a1));
+        QCOMPARE(QJsonValue(a3[1]), QJsonValue(o));
+        QCOMPARE(QJsonValue(a3[2]), QJsonValue(a2));
+
+        QJsonArray a4 { 1, QJsonArray{1,2,3}, QJsonArray{"hello", 2} };
+        QCOMPARE(a4.count(), 3);
+        QCOMPARE(QJsonValue(a4[0]), QJsonValue(1));
+
+        {
+            QJsonArray a41 = a4[1].toArray();
+            QJsonArray a42 = a4[2].toArray();
+            QCOMPARE(a41.count(), 3);
+            QCOMPARE(a42.count(), 2);
+
+            QCOMPARE(QJsonValue(a41[2]), QJsonValue(3));
+            QCOMPARE(QJsonValue(a42[1]), QJsonValue(2));
+        }
+    }
+#endif
+}
+
 QTEST_MAIN(tst_QtJson)
 #include "tst_qtjson.moc"