1 files changed, 111 insertions, 0 deletions
diff --git a/sql/opt_rewrite_date_cmp.h b/sql/opt_rewrite_date_cmp.h
new file mode 100644
index 00000000000..9f6e1d74ffa
--- /dev/null
+++ b/sql/opt_rewrite_date_cmp.h
@@ -0,0 +1,111 @@
+/*
+   Copyright (c) 2023, MariaDB
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1335  USA */
+
+#ifndef OPT_REWRITE_DATE_CMP_INCLUDED
+#define OPT_REWRITE_DATE_CMP_INCLUDED
+
+class Item_func_eq;
+class Item_func_ge;
+class Item_func_gt;
+class Item_func_le;
+class Item_func_lt;
+class Item_bool_rowready_func2;
+
+/*
+  @brief Class responsible for rewriting datetime comparison condition.
+         It rewrites non-sargable conditions into sargable.
+
+  @detail
+  The intent of this class is to do equivalent rewrites as follows:
+
+    YEAR(col) <= val  ->  col <= year_end(val)
+    YEAR(col) <  val  ->  col <  year_start(val)
+    YEAR(col) >= val  ->  col >= year_start(val)
+    YEAR(col) >  val  ->  col >  year_end(val)
+    YEAR(col) =  val  ->  col >= year_start(val) AND col<=year_end(val)
+
+  Also the same is done for comparisons with DATE(col):
+
+    DATE(col) <= val  ->  col <= day_end(val)
+
+  if col has a DATE type (not DATETIME), then the rewrite becomes:
+
+    DATE(col) <= val  ->  col <= val
+
+  @usage
+    Date_cmp_func_rewriter rwr(thd, item_func);
+    Item *new_item= rwr.get_rewrite_result();
+
+    Returned new_item points to an item that item_func was rewritten to.
+    new_item already has fixed fields (fix_fields() was called).
+    If no rewrite happened, new_item points to the initial item_func parameter
+
+  @todo
+    Also handle conditions in form "YEAR(date_col) BETWEEN 2014 AND 2017"
+    and "YEAR(col) = c1 AND MONTH(col) = c2"
+*/
+class Date_cmp_func_rewriter
+{
+public:
+  Date_cmp_func_rewriter(THD* thd, Item_func_eq *item_func);
+
+  Date_cmp_func_rewriter(THD* thd, Item_func_ge *item_func);
+
+  Date_cmp_func_rewriter(THD* thd, Item_func_gt *item_func);
+
+  Date_cmp_func_rewriter(THD* thd, Item_func_le *item_func);
+
+  Date_cmp_func_rewriter(THD* thd, Item_func_lt *item_func);
+
+  Item* get_rewrite_result() const { return result; }
+
+  Date_cmp_func_rewriter() = delete;
+  Date_cmp_func_rewriter(const Date_cmp_func_rewriter&) = delete;
+  Date_cmp_func_rewriter(Date_cmp_func_rewriter&&) = delete;
+
+private:
+  bool check_cond_match_and_prepare(Item_bool_rowready_func2 *item_func);
+  Item_field *is_date_rounded_field(Item* item,
+                                    const Type_handler *comparison_type,
+                                    Item_func::Functype *out_func_type) const;
+  void rewrite_le_gt_lt_ge();
+  Item *create_start_bound();
+  Item *create_end_bound();
+  Item *create_cmp_func(Item_func::Functype func_type, Item *arg1, Item *arg2);
+
+  THD *thd= nullptr;
+  Item *const_arg_value= nullptr;
+  Item_func::Functype rewrite_func_type= Item_func::UNKNOWN_FUNC;
+  Item_func::Functype argument_func_type= Item_func::UNKNOWN_FUNC;
+  Item_field *field_ref= nullptr;
+  Item *result= nullptr;
+};
+
+
+void trace_date_item_rewrite(THD *thd,Item *new_item, Item *old_item);
+
+template<typename T>
+Item* do_date_conds_transformation(THD *thd, T *item)
+{
+  Date_cmp_func_rewriter rwr(thd, item);
+  /* If the rewrite failed for some reason, we get the original item */
+  Item *new_item= rwr.get_rewrite_result();
+  trace_date_item_rewrite(thd, new_item, item);
+  return new_item;
+}
+
+
+#endif