Add new STRCMP2 Binary Function

Author: arjunsk

sql/item_cmpfunc.cc

@@ -2687,6 +2687,27 @@ longlong Item_func_strcmp::val_int() {
   return value == 0 ? 0 : value < 0 ? -1 : 1;
 }
 
+longlong Item_func_strcmp2::val_int() {
+  assert(fixed);
+  const CHARSET_INFO *cs = cmp.cmp_collation.collation;
+  String *a = eval_string_arg(cs, args[0], &cmp.value1);
+  if (a == nullptr) {
+    if (current_thd->is_error()) return error_int();
+    null_value = true;
+    return 0;
+  }
+
+  String *b = eval_string_arg(cs, args[1], &cmp.value2);
+  if (b == nullptr) {
+    if (current_thd->is_error()) return error_int();
+    null_value = true;
+    return 0;
+  }
+  int value = sortcmp(a, b, cs);
+  null_value = false;
+  return value == 0 ? 0 : value < 0 ? -1 : 1;
+}
+
 bool Item_func_opt_neg::eq(const Item *item, bool binary_cmp) const {
   /* Assume we don't have rtti */
   if (this == item) return true;

sql/item_cmpfunc.h

@@ -1378,6 +1378,27 @@ class Item_func_strcmp final : public Item_bool_func2 {
   }
 };
 
+class Item_func_strcmp2 final : public Item_bool_func2 {
+public:
+  Item_func_strcmp2(const POS &pos, Item *a, Item *b): Item_bool_func2(pos, a, b) {}
+  longlong val_int() override;
+  optimize_type select_optimize(const THD *) override { return OPTIMIZE_NONE; }
+  const char *func_name() const override { return "strcmp2"; }
+  enum Functype functype() const override { return STRCMP_FUNC2; }
+
+  void print(const THD *thd, String *str,enum_query_type query_type) const override {
+    Item_func::print(thd, str, query_type);
+  }
+  // We derive (indirectly) from Item_bool_func, but this is not a true boolean.
+  // Override length and unsigned_flag set by set_data_type_bool().
+  bool resolve_type(THD *thd) override {
+    if (Item_bool_func2::resolve_type(thd)) return true;
+    fix_char_length(2);  // returns "1" or "0" or "-1"
+    unsigned_flag = false;
+    return false;
+  }
+};
+
 struct interval_range {
   Item_result type;
   double dbl;

sql/item_create.cc

@@ -1553,8 +1553,9 @@ static const std::pair<const char *, Create_func *> func_array[] = {
     {"WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS",
      SQL_FN_V(Item_master_gtid_set_wait, 1, 3)},
     {"SQRT", SQL_FN(Item_func_sqrt, 1)},
- {"SQRT_LOG", SQL_FN(Item_func_sqrt_log, 1)},
+{"SQRT_LOG", SQL_FN(Item_func_sqrt_log, 1)},
     {"STRCMP", SQL_FN(Item_func_strcmp, 2)},
+{"STRCMP2", SQL_FN(Item_func_strcmp2, 2)},
     {"STR_TO_DATE", SQL_FN(Item_func_str_to_date, 2)},
     {"ST_AREA", SQL_FN(Item_func_st_area, 1)},
     {"ST_ASBINARY", SQL_FN_V(Item_func_as_wkb, 1, 2)},

sql/item_func.h

@@ -304,6 +304,7 @@ class Item_func : public Item_result_field {
     JSON_UNQUOTE_FUNC,
     MEMBER_OF_FUNC,
     STRCMP_FUNC,
+    STRCMP_FUNC2,
     TRUE_FUNC,
     FALSE_FUNC
   };