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src/sql/engine/expr/ob_expr_dll_udf.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 OB_EXPR_UDF_H_
+#define OB_EXPR_UDF_H_
+
+#include "sql/engine/expr/ob_expr_operator.h"
+#include "sql/engine/expr/ob_sql_expression_factory.h"
+#include "sql/engine/expr/ob_expr_operator_factory.h"
+#include "sql/engine/user_defined_function/ob_udf_util.h"
+#include "sql/engine/user_defined_function/ob_user_defined_function.h"
+#include "sql/code_generator/ob_expr_generator_impl.h"
+
+namespace oceanbase {
+namespace sql {
+class ObRawExpr;
+class ObSqlExpression;
+
+class ObExprDllUdf : public ObFuncExprOperator {
+  OB_UNIS_VERSION_V(1);
+
+  public:
+  explicit ObExprDllUdf(ObIAllocator& alloc);
+  ObExprDllUdf(ObIAllocator& alloc, ObExprOperatorType type, const char* name);
+  virtual ~ObExprDllUdf();
+  virtual int calc_result_typeN(
+      ObExprResType& type, ObExprResType* types_stack, int64_t param_num, common::ObExprTypeCtx& type_ctx) const;
+
+  virtual int calc_resultN(
+      common::ObObj& result, const common::ObObj* objs_stack, int64_t param_num, common::ObExprCtx& expr_ctx) const;
+
+  public:
+  int set_udf_meta(const share::schema::ObUDFMeta& udf);
+  int init_udf(const common::ObIArray<ObRawExpr*>& para_exprs);
+  common::ObIArray<common::ObString>& get_udf_attribute()
+  {
+    return udf_attributes_;
+  };
+  common::ObIArray<ObExprResType>& get_udf_attributes_types()
+  {
+    return udf_attributes_types_;
+  };
+  ObNormalUdfFunction& get_udf_func()
+  {
+    return udf_func_;
+  };
+  int add_const_expression(ObSqlExpression* sql_calc, int64_t idx_in_udf_arg);
+
+  protected:
+  common::ObIAllocator& allocator_;
+  ObNormalUdfFunction udf_func_;
+  ObUdfFunction::ObUdfCtx udf_ctx_;
+  share::schema::ObUDFMeta udf_meta_;
+  common::ObSEArray<common::ObString, 16> udf_attributes_;    /* udf's input args' name */
+  common::ObSEArray<ObExprResType, 16> udf_attributes_types_; /* udf's attribute type */
+  /*
+   * mysql require the calculable expression got result before we invoke the xxx_init() function.
+   * it seems no other choice.
+   * just like table location, the udf expr must have the capable of calculating the inner expression.
+   * so we set a ObSqlExpressionFactory as his data member.
+   * the overhead seems unavoidable. all our calculation tight coupling with SQL execution.
+   * as we can see, all the behaviors of mysql shows that it don't split the expression operator into
+   * logical and physical stage.
+   * */
+  common::ObSEArray<ObUdfConstArgs, 16> calculable_results_; /* calculable input expr' param idx */
+  ObSqlExpressionFactory sql_expression_factory_;
+  ObExprOperatorFactory expr_op_factory_;
+};
+
+}  // namespace sql
+}  // namespace oceanbase
+
+#endif