refactor: introduce helper method to extract logic

Signed-off-by: Andres Taylor <andres@planetscale.com>

go/vt/sqlparser/ast_funcs.go

@@ -1190,6 +1190,14 @@ func (node *Select) AddGroupBy(expr Expr) {
  node.GroupBy.Exprs = append(node.GroupBy.Exprs, expr)
 }
 
+// GroupByExprs returns the group by expressions
+func (node *Select) GroupByExprs() []Expr {
+ if node.GroupBy == nil {
+ return nil
+ }
+ return node.GroupBy.Exprs
+}
+
 // AddWhere adds the boolean expression to the
 // WHERE clause as an AND condition.
 func (node *Update) AddWhere(expr Expr) {

go/vt/vtgate/semantics/binder.go

@@ -382,19 +382,17 @@ func (b *binder) searchInSelectExpressions(colName *sqlparser.ColName, deps depe
  return dependency{certain: true, direct: direct, recursive: recursive, typ: typ}
  }
  }
- if stmt.GroupBy != nil {
- for _, gb := range stmt.GroupBy.Exprs {
- selectCol, ok := gb.(*sqlparser.ColName)
- if !ok || !selectCol.Name.Equal(colName.Name) {
- continue
- }
+ for _, gb := range stmt.GroupByExprs() {
+ selectCol, ok := gb.(*sqlparser.ColName)
+ if !ok || !selectCol.Name.Equal(colName.Name) {
+ continue
+ }
 
- _, direct, _ := b.org.depsForExpr(selectCol)
- if deps.direct == direct {
- // we have found the ColName in the GROUP BY expressions, so it's safe to use here
- direct, recursive, typ := b.org.depsForExpr(gb)
- return dependency{certain: true, direct: direct, recursive: recursive, typ: typ}
- }
+ _, direct, _ := b.org.depsForExpr(selectCol)
+ if deps.direct == direct {
+ // we have found the ColName in the GROUP BY expressions, so it's safe to use here
+ direct, recursive, typ := b.org.depsForExpr(gb)
+ return dependency{certain: true, direct: direct, recursive: recursive, typ: typ}
  }
  }
  return dependency{}