MB-53947 Detect quoted system keyspace name

Change-Id: I1853b00cde9b0be7081705ced237c3d609e81f94
Reviewed-on: https://review.couchbase.org/c/query/+/180725
Reviewed-by: Marco Greco <marco.greco@couchbase.com>
Tested-by: Donald Haggart <donald.haggart@couchbase.com>

inferencer/document_retrievers.go

@@ -901,6 +901,7 @@ func MakeExpressionDocumentRetriever(context datastore.QueryContext, expr expres
 		}
 		// stream subqueries to save on caching a potentially large result-set all at once, even though it means processing this
 		// statement a second time
+		logging.Debuga(func() string { return sq.Select().String() })
 		edr.subquery, err = ectx.OpenStatement(sq.Select().String(), nil, nil, false, true)
 		if err != nil {
 			return nil, errors.NewInferExpressionEvalFailed(err)

parser/n1ql/n1ql.go

@@ -15,6 +15,7 @@ import (
 	"strings"
 
 	"github.com/couchbase/query/algebra"
+	"github.com/couchbase/query/datastore"
 	"github.com/couchbase/query/expression"
 	"github.com/couchbase/query/logging"
 )
@@ -166,9 +167,15 @@ func (this *lexer) Lex(lval *yySymType) int {
 	}
 
 	// is it a namespace?
-	_, found := namespaces[lval.s]
+	tok := lval.s
+	if tok[0] == '#' {
+		tok = tok[1:]
+	}
+	_, found := namespaces[tok]
 	if !found {
 		return IDENT
+	} else {
+		lval.s = tok
 	}
 
 	// save the current token value and check the next
@@ -183,6 +190,10 @@ func (this *lexer) Lex(lval *yySymType) int {
 		return IDENT
 	}
 
+	if lval.s == datastore.GetSystemstore().Id() {
+		return SYSTEM
+	}
+
 	return NAMESPACE_ID
 }