Add default value for getters in QJsonValue

Done-with: Debao Zhang <dbzhang800@gmail.com>
Change-Id: I3ddd8dd89dc75d91ac9977bf9b6eb3174d7669e4
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

src/corelib/json/qjsonvalue.cpp

@@ -369,36 +369,36 @@ QJsonValue::Type QJsonValue::type() const
 /*!
     Converts the value to a bool and returns it.
 
-    If type() is not bool, false will be returned.
+    If type() is not bool, the defaultValue will be returned.
  */
-bool QJsonValue::toBool() const
+bool QJsonValue::toBool(bool defaultValue) const
 {
     if (t != Bool)
-        return false;
+        return defaultValue;
     return b;
 }
 
 /*!
     Converts the value to a double and returns it.
 
-    If type() is not Double, 0. will be returned.
+    If type() is not Double, the defaultValue will be returned.
  */
-double QJsonValue::toDouble() const
+double QJsonValue::toDouble(double defaultValue) const
 {
     if (t != Double)
-        return 0;
+        return defaultValue;
     return dbl;
 }
 
 /*!
     Converts the value to a QString and returns it.
 
-    If type() is not String, a QString() will be returned.
+    If type() is not String, the defaultValue will be returned.
  */
-QString QJsonValue::toString() const
+QString QJsonValue::toString(const QString &defaultValue) const
 {
     if (t != String)
-        return QString();
+        return defaultValue;
     stringData->ref.ref(); // the constructor below doesn't add a ref.
     QStringDataPtr holder = { stringData };
     return QString(holder);
@@ -407,27 +407,51 @@ QString QJsonValue::toString() const
 /*!
     Converts the value to an array and returns it.
 
-    If type() is not Array, a QJsonArray() will be returned.
+    If type() is not Array, the defaultValue will be returned.
  */
-QJsonArray QJsonValue::toArray() const
+QJsonArray QJsonValue::toArray(const QJsonArray &defaultValue) const
 {
     if (!d || t != Array)
-        return QJsonArray();
+        return defaultValue;
 
     return QJsonArray(d, static_cast<QJsonPrivate::Array *>(base));
 }
 
+/*!
+    \overload
+
+    Converts the value to an array and returns it.
+
+    If type() is not Array, a QJsonArray() will be returned.
+ */
+QJsonArray QJsonValue::toArray() const
+{
+    return toArray(QJsonArray());
+}
+
 /*!
     Converts the value to an object and returns it.
 
-    If type() is not Object, a QJsonObject() will be returned.
+    If type() is not Object, the defaultValue will be returned.
+ */
+QJsonObject QJsonValue::toObject(const QJsonObject &defaultValue) const
+{
+    if (!d || t != Object)
+        return defaultValue;
+
+    return QJsonObject(d, static_cast<QJsonPrivate::Object *>(base));
+}
+
+/*!
+    \overload
+
+    Converts the value to an object and returns it.
+
+    If type() is not Object, the QJsonObject() will be returned.
  */
 QJsonObject QJsonValue::toObject() const
 {
-    if (!d || t != Object)
+    return toObject(QJsonObject());
-        return QJsonObject();
-
-    return QJsonObject(d, static_cast<QJsonPrivate::Object *>(base));
 }
 
 /*!

src/corelib/json/qjsonvalue.h

@@ -103,11 +103,13 @@ public:
     inline bool isObject() const { return type() == Object; }
     inline bool isUndefined() const { return type() == Undefined; }
 
-    bool toBool() const;
+    bool toBool(bool defaultValue = false) const;
-    double toDouble() const;
+    double toDouble(double defaultValue = 0) const;
-    QString toString() const;
+    QString toString(const QString &defaultValue = QString()) const;
     QJsonArray toArray() const;
+    QJsonArray toArray(const QJsonArray &defaultValue) const;
     QJsonObject toObject() const;
+    QJsonObject toObject(const QJsonObject &defaultValue) const;
 
     bool operator==(const QJsonValue &other) const;
     bool operator!=(const QJsonValue &other) const;

tests/auto/corelib/json/tst_qtjson.cpp

@@ -154,6 +154,12 @@ void TestQtJson::cleanup()
 
 void TestQtJson::testValueSimple()
 {
+    QJsonObject object;
+    object.insert("number", 999.);
+    QJsonArray array;
+    for (int i = 0; i < 10; ++i)
+        array.append((double)i);
+
     QJsonValue value(true);
     QCOMPARE(value.type(), QJsonValue::Bool);
     QCOMPARE(value.toDouble(), 0.);
@@ -161,12 +167,17 @@ void TestQtJson::testValueSimple()
     QCOMPARE(value.toBool(), true);
     QCOMPARE(value.toObject(), QJsonObject());
     QCOMPARE(value.toArray(), QJsonArray());
+    QCOMPARE(value.toDouble(99.), 99.);
+    QCOMPARE(value.toString(QString("test")), QString("test"));
+    QCOMPARE(value.toObject(object), object);
+    QCOMPARE(value.toArray(array), array);
 
     value = 999.;
     QCOMPARE(value.type(), QJsonValue::Double);
     QCOMPARE(value.toDouble(), 999.);
     QCOMPARE(value.toString(), QString());
     QCOMPARE(value.toBool(), false);
+    QCOMPARE(value.toBool(true), true);
     QCOMPARE(value.toObject(), QJsonObject());
     QCOMPARE(value.toArray(), QJsonArray());
 
@@ -190,7 +201,6 @@ void TestQtJson::testValueSimple()
     QCOMPARE(value.toBool(), false);
     QCOMPARE(value.toObject(), QJsonObject());
     QCOMPARE(value.toArray(), QJsonArray());
-
 }
 
 void TestQtJson::testNumbers()