cleanup: Refactor select_limit in select lex

Replace
  * select_lex::offset_limit
  * select_lex::select_limit
  * select_lex::explicit_limit
with select_lex::Lex_select_limit

The Lex_select_limit already existed with the same elements and was used in
by the yacc parser.

This commit is in preparation for FETCH FIRST implementation, as it
simplifies a lot of the code.

Additionally, the parser is simplified by making use of the stack to
return Lex_select_limit objects.

Cleanup of init_query() too. Removes explicit_limit= 0 as it's done a bit later
in init_select() with limit_params.empty()

1 files changed, 4 insertions, 4 deletions

diff --git a/sql/sql_limit.h b/sql/sql_limit.h
index a4fcedac14a..943d96940bb 100644
--- a/sql/sql_limit.h
+++ b/sql/sql_limit.h
@@ -50,22 +50,22 @@ class Select_limit_counters
      select_limit_cnt= 1;
    }
 
-   bool is_unlimited()
+   bool is_unlimited() const
    { return select_limit_cnt == HA_POS_ERROR; }
    bool is_unrestricted()
    { return select_limit_cnt == HA_POS_ERROR && offset_limit_cnt == 0; }
    void set_unlimited()
    { select_limit_cnt= HA_POS_ERROR; offset_limit_cnt= 0; }
 
-   bool check_offset(ha_rows sent)
+   bool check_offset(ha_rows sent) const
    {
      return sent < offset_limit_cnt;
    }
    void remove_offset() { offset_limit_cnt= 0; }
 
-   ha_rows get_select_limit()
+   ha_rows get_select_limit() const
    { return select_limit_cnt; }
-   ha_rows get_offset_limit()
+   ha_rows get_offset_limit() const
    { return offset_limit_cnt; }
 };