Adjustments as per Adriano's comments

src/dsql/BoolNodes.cpp

@@ -1582,7 +1582,7 @@ BoolExprNode* RseBoolNode::pass1(thread_db* tdbb, CompilerScratch* csb)
 
 void RseBoolNode::pass2Boolean1(thread_db* tdbb, CompilerScratch* csb)
 {
-	if (!(rse->flags & RseNode::FLAG_VARIANT))
+	if (rse->isInvariant())
 	{
 		nodFlags |= FLAG_INVARIANT;
 		csb->csb_invariants.push(&impureOffset);

src/dsql/ExprNodes.cpp

@@ -11321,7 +11321,7 @@ ValueExprNode* SubQueryNode::pass2(thread_db* tdbb, CompilerScratch* csb)
 	if (!rse)
 		ERR_post(Arg::Gds(isc_wish_list));
 
-	if (!(rse->flags & RseNode::FLAG_VARIANT))
+	if (rse->isInvariant())
 	{
 		nodFlags |= FLAG_INVARIANT;
 		csb->csb_invariants.push(&impureOffset);

src/dsql/StmtNodes.cpp

@@ -5077,7 +5077,7 @@ StmtNode* ForNode::pass2(thread_db* tdbb, CompilerScratch* csb)
 
 	csb->csb_fors.add(cursor);
 
-	if (rse->flags & RseNode::FLAG_WRITELOCK)
+	if (rse->hasWriteLock())
 		withLock = true;
 
 	if (marks & MARK_MERGE)

src/dsql/gen.cpp

@@ -547,10 +547,10 @@ void GEN_rse(DsqlCompilerScratch* dsqlScratch, RseNode* rse)
 	for (const NestConst<RecordSourceNode>* const end = rse->dsqlStreams->items.end(); ptr != end; ++ptr)
 		GEN_expr(dsqlScratch, *ptr);
 
-	if (rse->flags & RseNode::FLAG_WRITELOCK)
+	if (rse->hasWriteLock())
 		dsqlScratch->appendUChar(blr_writelock);
 
-	if (rse->flags & RseNode::FLAG_SKIP_LOCKED)
+	if (rse->hasSkipLocked())
 		dsqlScratch->appendUChar(blr_skip_locked);
 
 	if (rse->dsqlFirst)

src/dsql/pass1.cpp

@@ -2177,13 +2177,13 @@ static RseNode* pass1_rse_impl(DsqlCompilerScratch* dsqlScratch, RecordSourceNod
 		parentRse->dsqlStreams = streamList = FB_NEW_POOL(pool) RecSourceListNode(pool, 1);
 		streamList->items[0] = window;
 
-		if (rse->flags & RseNode::FLAG_WRITELOCK)
+		if (rse->hasWriteLock())
 		{
 			parentRse->flags |= RseNode::FLAG_WRITELOCK;
 			rse->flags &= ~RseNode::FLAG_WRITELOCK;
 		}
 
-		if (rse->flags & RseNode::FLAG_SKIP_LOCKED)
+		if (rse->hasSkipLocked())
 		{
 			parentRse->flags |= RseNode::FLAG_SKIP_LOCKED;
 			rse->flags &= ~RseNode::FLAG_SKIP_LOCKED;

src/jrd/RecordSourceNodes.cpp

@@ -2951,9 +2951,7 @@ void RseNode::pass1Source(thread_db* tdbb, CompilerScratch* csb, RseNode* rse,
 	// where we are just trying to inner join more than 2 streams. If possible,
 	// try to flatten the tree out before we go any further.
 
-	const auto isLateral = (this->flags & RseNode::FLAG_LATERAL) != 0;
+	if (!isLateral() &&
-
-	if (!isLateral &&
 		rse->rse_jointype == blr_inner &&
 		rse_jointype == blr_inner &&
 		!rse_sorted && !rse_projection &&
@@ -3046,8 +3044,6 @@ RecordSource* RseNode::compile(thread_db* tdbb, Optimizer* opt, bool innerSubStr
 
 	BoolExprNodeStack conjunctStack;
 
-	const auto isLateral = (this->flags & RseNode::FLAG_LATERAL) != 0;
-
 	// pass RseNode boolean only to inner substreams because join condition
 	// should never exclude records from outer substreams
 	if (opt->isInnerJoin() || (opt->isLeftJoin() && innerSubStream))
@@ -3060,7 +3056,7 @@ RecordSource* RseNode::compile(thread_db* tdbb, Optimizer* opt, bool innerSubStr
 
 		StreamStateHolder stateHolder(csb, opt->getOuterStreams());
 
-		if (opt->isLeftJoin() || isLateral)
+		if (opt->isLeftJoin() || isLateral())
 		{
 			stateHolder.activate();
 

src/jrd/RecordSourceNodes.h

@@ -730,6 +730,41 @@ public:
 		FLAG_SUB_QUERY			= 0x100	// sub-query
 	};
 
+	bool isInvariant() const
+	{
+		return (flags & FLAG_VARIANT) == 0;
+	}
+
+	bool isSingular() const
+	{
+		return (flags & FLAG_SINGULAR) != 0;
+	}
+
+	bool isScrollable() const
+	{
+		return (flags & FLAG_SCROLLABLE) != 0;
+	}
+
+	bool isLateral() const
+	{
+		return (flags & FLAG_LATERAL) != 0;
+	}
+
+	bool isSubQuery() const
+	{
+		return (flags & FLAG_SUB_QUERY) != 0;
+	}
+
+	bool hasWriteLock() const
+	{
+		return (flags & FLAG_WRITELOCK) != 0;
+	}
+
+	bool hasSkipLocked() const
+	{
+		return (flags & FLAG_SKIP_LOCKED) != 0;
+	}
+
 	explicit RseNode(MemoryPool& pool)
 		: TypedNode<RecordSourceNode, RecordSourceNode::TYPE_RSE>(pool),
 		  dsqlFirst(NULL),

src/jrd/optimizer/Optimizer.cpp

@@ -1034,7 +1034,7 @@ RecordSource* Optimizer::compile(BoolExprNodeStack* parentStack)
 	if (rse->rse_skip)
 		rsb = FB_NEW_POOL(getPool()) SkipRowsStream(csb, rsb, rse->rse_skip);
 
-	if (rse->flags & RseNode::FLAG_WRITELOCK)
+	if (rse->hasWriteLock())
 	{
 		for (const auto compileStream : compileStreams)
 		{
@@ -1048,16 +1048,16 @@ RecordSource* Optimizer::compile(BoolExprNodeStack* parentStack)
 				SCL_update, obj_relations, tail->csb_relation->rel_name);
 		}
 
-		rsb = FB_NEW_POOL(getPool()) LockedStream(csb, rsb, (rse->flags & RseNode::FLAG_SKIP_LOCKED));
+		rsb = FB_NEW_POOL(getPool()) LockedStream(csb, rsb, rse->hasSkipLocked());
 	}
 
 	if (rse->rse_first)
 		rsb = FB_NEW_POOL(getPool()) FirstRowsStream(csb, rsb, rse->rse_first);
 
-	if (rse->flags & RseNode::FLAG_SINGULAR)
+	if (rse->isSingular())
 		rsb = FB_NEW_POOL(getPool()) SingularStream(csb, rsb);
 
-	if (rse->flags & RseNode::FLAG_SCROLLABLE)
+	if (rse->isScrollable())
 		rsb = FB_NEW_POOL(getPool()) BufferedStream(csb, rsb);
 
 	return rsb;

src/jrd/par.cpp

@@ -1404,7 +1404,7 @@ RseNode* PAR_rse(thread_db* tdbb, CompilerScratch* csb, SSHORT rse_op)
 			break;
 
 		case blr_skip_locked:
-			if (!(rse->flags & RseNode::FLAG_WRITELOCK))
+			if (!rse->hasWriteLock())
 			{
 				PAR_error(csb,
 					Arg::Gds(isc_random) <<

src/jrd/recsrc/Cursor.cpp

@@ -70,18 +70,18 @@ void Select::printPlan(thread_db* tdbb, string& plan, bool detailed) const
 {
 	if (detailed)
 	{
-		if (m_rse->flags & RseNode::FLAG_SUB_QUERY)
+		if (m_rse->isSubQuery())
 		{
 			plan += "\nSub-query";
 
-			if (!(m_rse->flags & RseNode::FLAG_VARIANT))
+			if (m_rse->isInvariant())
 				plan += " (invariant)";
 		}
 		else if (m_cursorName.hasData())
 		{
 			plan += "\nCursor \"" + string(m_cursorName) + "\"";
 
-			if (m_rse->flags & RseNode::FLAG_SCROLLABLE)
+			if (m_rse->isScrollable())
 				plan += " (scrollable)";
 		}
 		else
@@ -179,7 +179,7 @@ void Cursor::close(thread_db* tdbb) const
 
 bool Cursor::fetchNext(thread_db* tdbb) const
 {
-	if (m_rse->flags & RseNode::FLAG_SCROLLABLE)
+	if (m_rse->isScrollable())
 		return fetchRelative(tdbb, 1);
 
 	if (!validate(tdbb))
@@ -215,7 +215,7 @@ bool Cursor::fetchNext(thread_db* tdbb) const
 
 bool Cursor::fetchPrior(thread_db* tdbb) const
 {
-	if (!(m_rse->flags & RseNode::FLAG_SCROLLABLE))
+	if (!m_rse->isScrollable())
 	{
 		// error: invalid fetch direction
 		status_exception::raise(Arg::Gds(isc_invalid_fetch_option) << Arg::Str("PRIOR"));
@@ -226,7 +226,7 @@ bool Cursor::fetchPrior(thread_db* tdbb) const
 
 bool Cursor::fetchFirst(thread_db* tdbb) const
 {
-	if (!(m_rse->flags & RseNode::FLAG_SCROLLABLE))
+	if (!m_rse->isScrollable())
 	{
 		// error: invalid fetch direction
 		status_exception::raise(Arg::Gds(isc_invalid_fetch_option) << Arg::Str("FIRST"));
@@ -237,7 +237,7 @@ bool Cursor::fetchFirst(thread_db* tdbb) const
 
 bool Cursor::fetchLast(thread_db* tdbb) const
 {
-	if (!(m_rse->flags & RseNode::FLAG_SCROLLABLE))
+	if (!m_rse->isScrollable())
 	{
 		// error: invalid fetch direction
 		status_exception::raise(Arg::Gds(isc_invalid_fetch_option) << Arg::Str("LAST"));
@@ -248,7 +248,7 @@ bool Cursor::fetchLast(thread_db* tdbb) const
 
 bool Cursor::fetchAbsolute(thread_db* tdbb, SINT64 offset) const
 {
-	if (!(m_rse->flags & RseNode::FLAG_SCROLLABLE))
+	if (!m_rse->isScrollable())
 	{
 		// error: invalid fetch direction
 		status_exception::raise(Arg::Gds(isc_invalid_fetch_option) << Arg::Str("ABSOLUTE"));
@@ -309,7 +309,7 @@ bool Cursor::fetchAbsolute(thread_db* tdbb, SINT64 offset) const
 
 bool Cursor::fetchRelative(thread_db* tdbb, SINT64 offset) const
 {
-	if (!(m_rse->flags & RseNode::FLAG_SCROLLABLE))
+	if (!m_rse->isScrollable())
 	{
 		// error: invalid fetch direction
 		status_exception::raise(Arg::Gds(isc_invalid_fetch_option) << Arg::Str("RELATIVE"));

src/jrd/recsrc/Cursor.h

@@ -75,7 +75,7 @@ namespace Jrd
 
 	// SubQuery class (simplified forward-only cursor)
 
-	class SubQuery : public Select
+	class SubQuery final : public Select
 	{
 	public:
 		SubQuery(const RecordSource* rsb, const RseNode* rse);
@@ -88,7 +88,7 @@ namespace Jrd
 
 	// Cursor class (wrapper around the whole access tree)
 
-	class Cursor : public Select
+	class Cursor final : public Select
 	{
 		enum State { BOS, POSITIONED, EOS };