Introduce Utils::DisplayName

The concept of a default display name as used in ProjectConfiguration is
useful, and we'd like to use it elsewhere.

Change-Id: I10d9a5bd3d3e385a99f1122c6b119136662502fa
Reviewed-by: hjk <hjk@qt.io>

src/libs/utils/displayname.cpp

@@ -0,0 +1,76 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+****************************************************************************/
+
+#include "displayname.h"
+
+namespace Utils {
+
+bool DisplayName::setValue(const QString &name)
+{
+    if (value() == name)
+        return false;
+    if (name == m_defaultValue)
+        m_value.clear();
+    else
+        m_value = name;
+    return true;
+}
+
+bool DisplayName::setDefaultValue(const QString &name)
+{
+    if (m_defaultValue == name)
+        return false;
+    const QString originalName = value();
+    m_defaultValue = name;
+    return originalName != value();
+}
+
+QString DisplayName::value() const
+{
+    return m_value.isEmpty() ? m_defaultValue : m_value;
+}
+
+bool DisplayName::usesDefaultValue() const
+{
+    return m_value.isEmpty();
+}
+
+void DisplayName::toMap(QVariantMap &map, const QString &key) const
+{
+    if (!usesDefaultValue())
+        map.insert(key, m_value);
+}
+
+void DisplayName::fromMap(const QVariantMap &map, const QString &key)
+{
+    m_value = map.value(key).toString();
+}
+
+bool operator==(const DisplayName &dn1, const DisplayName &dn2)
+{
+    return dn1.value() == dn2.value() && dn1.defaultValue() == dn2.defaultValue();
+}
+
+} // namespace Utils