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src/sql/optimizer/ob_raw_expr_get_hash_value.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_RAW_EXPR_GET_HASH_VALUE_H
+#define _OB_RAW_EXPR_GET_HASH_VALUE_H 1
+#include "sql/optimizer/ob_logical_operator.h"
+#include "sql/resolver/expr/ob_raw_expr.h"
+
+namespace oceanbase {
+namespace sql {
+/**
+ *  This class is used to traverse an expression tree in a post-order fashion to
+ *  add all required expressions into the context data structure, which is used
+ *  during output expr allocation.
+ */
+class ObRawExprGetHashValue : public ObRawExprVisitor {
+  public:
+  ObRawExprGetHashValue(uint64_t seed) : seed_(seed)
+  {}
+  virtual ~ObRawExprGetHashValue()
+  {}
+
+  /**
+   *  The starting point
+   */
+  int get_hash_value(ObRawExpr& expr);
+
+  /// interface of ObRawExprVisitor
+  virtual int visit(ObConstRawExpr& expr);
+  virtual int visit(ObVarRawExpr& expr);
+  virtual int visit(ObQueryRefRawExpr& expr);
+  virtual int visit(ObColumnRefRawExpr& expr);
+  virtual int visit(ObOpRawExpr& expr);
+  virtual int visit(ObCaseOpRawExpr& expr);
+  virtual int visit(ObAggFunRawExpr& expr);
+  virtual int visit(ObSysFunRawExpr& expr);
+  virtual int visit(ObSetOpRawExpr& expr);
+
+  private:
+  int add_expr(ObRawExpr& expr);
+
+  private:
+  uint64_t seed_;
+  // disallow copy
+  DISALLOW_COPY_AND_ASSIGN(ObRawExprGetHashValue);
+};
+}  // namespace sql
+}  // namespace oceanbase
+
+#endif  // _OB_RAW_EXPR_GET_HASH_VALUE_H