QJson: Move writing from QJsonDocument to QJsonValue

JSON values are now written directly by QJsonValue instead of
QJsonDocument. Only objects and arrays are currently supported to be
written.

Change-Id: I413db14c69e8d6e9f06431051c8d716d1fb9d4eb
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/serialization/qjsonvalue.cpp

@@ -15,6 +15,7 @@
 #include <qdebug.h>
 #include "qdatastream.h"
 #include "qjsonparser_p.h"
+#include "qjsonwriter_p.h"
 
 #include <private/qnumeric_p.h>
 #include <private/qcborvalue_p.h>
@@ -606,7 +607,7 @@ QVariant QJsonValue::toVariant() const
 
     Currently, only objects/maps and arrays/lists can be parsed.
 
-    \sa QJsonParseError, isUndefined()
+    \sa QJsonParseError, isUndefined(), toJson()
  */
 QJsonValue QJsonValue::fromJson(QByteArrayView json, QJsonParseError *error)
 {
@@ -616,6 +617,43 @@ QJsonValue QJsonValue::fromJson(QByteArrayView json, QJsonParseError *error)
     return result;
 }
 
+/*!
+    \enum QJsonValue::JsonFormat
+    \since 6.9
+
+    This value defines the format of the JSON byte array produced
+    when converting to a QJsonValue using toJson().
+
+    \value Indented Defines human readable output as follows:
+        \snippet code/src_corelib_serialization_qjsondocument.cpp 0
+
+    \value Compact Defines a compact output as follows:
+        \snippet code/src_corelib_serialization_qjsondocument.cpp 1
+  */
+
+/*!
+    \since 6.9
+    Converts the QJsonValue to a UTF-8 encoded JSON value in the provided \a format.
+
+    Currently, only objects/maps and arrays/lists can be encoded.
+
+    \sa fromJson(), JsonFormat
+ */
+#if !defined(QT_JSON_READONLY) || defined(Q_QDOC)
+QByteArray QJsonValue::toJson(JsonFormat format) const
+{
+    QByteArray json;
+
+    const QCborContainerPrivate *container = QJsonPrivate::Value::container(value);
+    if (isArray())
+        QJsonPrivate::Writer::arrayToJson(container, json, 0, (format == Compact));
+    else
+        QJsonPrivate::Writer::objectToJson(container, json, 0, (format == Compact));
+
+    return json;
+}
+#endif
+
 /*!
     Returns the type of the value.
 

src/corelib/serialization/qjsonvalue.h

@@ -35,6 +35,11 @@ class Q_CORE_EXPORT QJsonValue
         Undefined = 0x80
     };
 
+    enum JsonFormat {
+        Indented,
+        Compact,
+    };
+
     QJsonValue(Type = Null);
     QJsonValue(bool b);
     QJsonValue(double n);
@@ -71,6 +76,10 @@ class Q_CORE_EXPORT QJsonValue
 
     static QJsonValue fromJson(QByteArrayView json, QJsonParseError *error = nullptr);
 
+#if !defined(QT_JSON_READONLY) || defined(Q_QDOC)
+    QByteArray toJson(JsonFormat format = JsonFormat::Indented) const;
+#endif
+
     Type type() const;
     inline bool isNull() const { return type() == Null; }
     inline bool isBool() const { return type() == Bool; }