Skip the row loop of a column walk when a table has no token cells, and scan a cell for braces by byte

graph.go

@@ -63,6 +63,9 @@ func contained(n node) []namedNode {
 	case *table:
 		return append([]namedNode{{node: n.format}}, named(n.fields)...)
 	case *column:
+		if len(n.t.tokens) == 0 {
+			return nil
+		}
 		var out []namedNode
 		for r := 0; r < n.t.rows(); r++ {
 			if cell := n.t.cellNode(r, n.i); cell != nil {

table.go

@@ -285,7 +285,7 @@ func (t *table) checkCells() error {
 		if (col == t.key || col == t.name) && strings.ContainsAny(cell, inSelector) {
 			return fmt.Errorf("line %d: %s %q contains %q, which a selector cannot spell", row+2, t.columns[col], cell, cell[strings.IndexAny(cell, inSelector):][:1])
 		}
-		if !strings.ContainsAny(cell, "{}") {
+		if strings.IndexByte(cell, '{') < 0 && strings.IndexByte(cell, '}') < 0 {
 			continue
 		}
 		n, err := compileString(cell)