Implementation of CSS3 nav-up/down/left/right properties from CSS3 UI.

Source/core/rendering/style/StyleNavigationValue.h

+/*
+ * Copyright (C) 2011 Kyounga Ra (kyounga.ra@gmail.com)
+ * Copyright (C) 2014 Opera Software ASA. All rights reserved.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public License
+ * along with this library; see the file COPYING.LIB.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef StyleNavigationValue_h
+#define StyleNavigationValue_h
+
+#include "core/rendering/style/RenderStyleConstants.h"
+#include "wtf/text/WTFString.h"
+
+namespace blink {
+
+class StyleNavigationValue {
+public:
+    StyleNavigationValue()
+        : m_auto(1)
+        , m_navigationTarget(Current)
+    { }
+
+    explicit StyleNavigationValue(const String& id, ENavigationTarget target = Current)
+        : m_auto(0)
+        , m_navigationTarget(target)
+        , m_id(AtomicString(id))
+    { }
+
+    StyleNavigationValue(const String& id, const String& target)
+        : m_auto(0)
+        , m_navigationTarget(TargetName)
+        , m_id(AtomicString(id))
+        , m_targetName(AtomicString(target))
+    { }
+
+    bool operator==(const StyleNavigationValue& o) const
+    {
+        if (m_auto)
+            return o.m_auto;
+        if (m_id != o.m_id)
+            return false;
+        if (m_navigationTarget == TargetName && m_targetName != o.m_targetName)
+            return false;
+        return m_navigationTarget == o.m_navigationTarget;
+    }
+
+    bool operator!=(const StyleNavigationValue& o) const
+    {
+        return !(*this == o);
+    }
+
+    bool isAuto() const { return m_auto; }
+    const AtomicString& id() const { return m_id; }
+    ENavigationTarget navigationTarget() { return static_cast<ENavigationTarget>(m_navigationTarget); }
+    const AtomicString& targetName() const { return m_targetName; }
+
+private:
+    unsigned m_auto : 1;
+    unsigned m_navigationTarget : 2; // ENavigationTarget
+    AtomicString m_id;
+    AtomicString m_targetName;
+};
+
+} // namespace blink
+
+#endif // StyleNavigationValue_h