Introduce LiteralSet

Source/core/dom/QualifiedName.h

Index: Source/core/dom/QualifiedName.h
diff --git a/Source/core/dom/QualifiedName.h b/Source/core/dom/QualifiedName.h
index 38673154a67f16684d3b44f5d599e697de86d8cd..891651e87e2ad66dae392d0cea0ac3804db78910 100644
--- a/Source/core/dom/QualifiedName.h
+++ b/Source/core/dom/QualifiedName.h
@@ -21,10 +21,11 @@
 #ifndef QualifiedName_h
 #define QualifiedName_h
 
-#include <wtf/Forward.h>
-#include <wtf/HashTraits.h>
-#include <wtf/RefCounted.h>
-#include <wtf/text/AtomicString.h>
+#include "wtf/Forward.h"
+#include "wtf/HashTraits.h"
+#include "wtf/LiteralSet.h"
+#include "wtf/RefCounted.h"
+#include "wtf/text/AtomicString.h"
 
 namespace WebCore {
 
@@ -128,6 +129,24 @@ inline unsigned hashComponents(const QualifiedNameComponents& buf)
     return StringHasher::hashMemory<sizeof(QualifiedNameComponents)>(&buf);
 }
 
+struct QualifiedNameComparer {
+    static bool lessThan(const QualifiedName* const& a, const QualifiedName* const& b)
+    {
+        return a->impl() < b->impl();
+    }
+};
+
+typedef LiteralSet<const QualifiedName*, QualifiedNameComparer> QualifiedNameLiteralSet;
+
+struct LocalNameComparer {
+    static bool lessThan(const QualifiedName* const& a, const QualifiedName* const& b)
+    {
+        return a->localName().impl() < b->localName().impl();
+    }
+};
+
+typedef LiteralSet<const QualifiedName*, LocalNameComparer> LocalNameLiteralSet;
+
 struct QualifiedNameHash {
     static unsigned hash(const QualifiedName& name) { return hash(name.impl()); }