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src/sql/engine/expr/ob_expr_random.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_OB_EXPR_FUNC_RANDOM_H_
+#define OCEANBASE_SQL_OB_EXPR_FUNC_RANDOM_H_
+
+#include "sql/engine/expr/ob_expr_operator.h"
+
+namespace oceanbase {
+namespace sql {
+class ObExprRandom : public ObFuncExprOperator {
+  OB_UNIS_VERSION(1);
+  class ObExprRandomCtx : public ObExprOperatorCtx {
+    public:
+    ObExprRandomCtx();
+    virtual ~ObExprRandomCtx();
+    void set_seed(uint32_t seed);
+    void get_next_random(double& res);
+
+    private:
+    static const uint64_t max_value_;
+    uint64_t seed1_;
+    uint64_t seed2_;
+  };
+
+  public:
+  explicit ObExprRandom(common::ObIAllocator& alloc);
+  virtual ~ObExprRandom();
+  virtual int calc_result_typeN(
+      ObExprResType& type, ObExprResType* types, int64_t param_num, common::ObExprTypeCtx& type_ctx) const;
+  virtual int calc_resultN(
+      common::ObObj& result, const common::ObObj* objs, int64_t param_num, common::ObExprCtx& expr_ctx) const;
+  inline void set_seed_const(bool is_seed_const);
+
+  // engine 3.0
+  virtual bool need_rt_ctx() const override
+  {
+    return true;
+  }
+  virtual int cg_expr(ObExprCGCtx& expr_cg_ctx, const ObRawExpr& raw_expr, ObExpr& rt_expr) const override;
+  static int calc_random_expr_const_seed(const ObExpr& expr, ObEvalCtx& ctx, ObDatum& res_datum);
+  static int calc_random_expr_nonconst_seed(const ObExpr& expr, ObEvalCtx& ctx, ObDatum& res_datum);
+
+  public:
+  virtual int assign(const ObExprOperator& other) override;
+
+  private:
+  bool is_seed_const_;
+  // disallow copy
+  DISALLOW_COPY_AND_ASSIGN(ObExprRandom);
+};
+
+inline void ObExprRandom::set_seed_const(bool is_seed_const)
+{
+  is_seed_const_ = is_seed_const;
+}
+} /* namespace sql */
+} /* namespace oceanbase */
+
+#endif /* OCEANBASE_SQL_OB_EXPR_FUNC_RANDOM_H_ */