Add a distinct tag class for file analyzers.

This should prevent assignment mismatches between file and protocol
analyzer tags.

src/Tag.cc

@@ -0,0 +1,82 @@
+// See the file "COPYING" in the main distribution directory for copyright.
+
+#include "Tag.h"
+#include "Val.h"
+
+Tag::Tag(EnumType* etype, type_t arg_type, subtype_t arg_subtype)
+	{
+	assert(arg_type > 0);
+
+	type = arg_type;
+	subtype = arg_subtype;
+	int64_t i = (int64)(type) | ((int64)subtype << 31);
+	Ref(etype);
+	val = new EnumVal(i, etype);
+	}
+
+Tag::Tag(EnumVal* arg_val)
+	{
+	assert(arg_val);
+
+	val = arg_val;
+	Ref(val);
+
+	int64 i = val->InternalInt();
+	type = i & 0xffffffff;
+	subtype = (i >> 31) & 0xffffffff;
+	}
+
+Tag::Tag(const Tag& other)
+	{
+	type = other.type;
+	subtype = other.subtype;
+	val = other.val;
+
+	if ( val )
+		Ref(val);
+	}
+
+Tag::Tag()
+	{
+	type = 0;
+	subtype = 0;
+	val = 0;
+	}
+
+Tag::~Tag()
+	{
+	Unref(val);
+	val = 0;
+	}
+
+Tag& Tag::operator=(const Tag& other)
+	{
+	if ( this != &other )
+		{
+		type = other.type;
+		subtype = other.subtype;
+		val = other.val;
+
+		if ( val )
+			Ref(val);
+		}
+
+	return *this;
+	}
+
+EnumVal* Tag::AsEnumVal(EnumType* etype) const
+	{
+	if ( ! val )
+		{
+		assert(type == 0 && subtype == 0);
+		Ref(etype);
+		val = new EnumVal(0, etype);
+		}
+
+	return val;
+	}
+
+std::string Tag::AsString() const
+	{
+	return fmt("%" PRIu32 "/%" PRIu32, type, subtype);
+	}