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src/sql/engine/expr/ob_expr_reverse.h

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+/**
+ * Copyright (c) 2021 OceanBase
+ * OceanBase CE is licensed under Mulan PubL v2.
+ * You can use this software according to the terms and conditions of the Mulan PubL v2.
+ * You may obtain a copy of Mulan PubL v2 at:
+ *          http://license.coscl.org.cn/MulanPubL-2.0
+ * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
+ * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
+ * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
+ * See the Mulan PubL v2 for more details.
+ */
+
+#ifndef OCEANBASE_SQL_EXPR_FUNC_REVERSE_
+#define OCEANBASE_SQL_EXPR_FUNC_REVERSE_
+
+#include "sql/engine/expr/ob_expr_operator.h"
+
+namespace oceanbase {
+namespace sql {
+class ObExprReverse : public ObStringExprOperator {
+  public:
+  explicit ObExprReverse(common::ObIAllocator& alloc);
+  virtual ~ObExprReverse();
+  virtual int calc_result_type1(ObExprResType& type, ObExprResType& type1, common::ObExprTypeCtx& type_ctx) const;
+  virtual int calc_result1(common::ObObj& result, const common::ObObj& input, common::ObExprCtx& expr_ctx) const;
+  virtual int cg_expr(ObExprCGCtx& expr_cg_ctx, const ObRawExpr& raw_expr, ObExpr& rt_expr) const;
+  static int do_reverse(const common::ObString& input_str, const common::ObCollationType& cs_type,
+      common::ObIAllocator* allocator, common::ObString& res_str);
+
+  private:
+  DISALLOW_COPY_AND_ASSIGN(ObExprReverse);
+};
+
+inline int ObExprReverse::calc_result_type1(
+    ObExprResType& type, ObExprResType& type1, common::ObExprTypeCtx& type_ctx) const
+{
+  UNUSED(type_ctx);
+  type1.set_calc_type(common::ObVarcharType);
+  type1.set_calc_collation_type(type1.get_collation_type());
+  type.set_varchar();
+  type.set_length(type1.get_length());
+  return aggregate_charsets_for_string_result(type, &type1, 1, type_ctx.get_coll_type());
+}
+
+}  // namespace sql
+}  // namespace oceanbase
+
+#endif /* OCEANBASE_SQL_EXPR_FUNC_REVERSE_ */