column.h

/* Copyright (c) 2021 OceanBase and/or its affiliates. All rights reserved.
miniob is licensed under Mulan PSL v2.
You can use this software according to the terms and conditions of the Mulan PSL v2.
You may obtain a copy of Mulan PSL v2 at:
         http://license.coscl.org.cn/MulanPSL2
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 PSL v2 for more details. */
 
#pragma once
 
#include <string.h>
 
#include "storage/field/field_meta.h"
 
// TODO: `Column` currently only support fixed-length type.
class Column
{
public:
  enum class Type
  {
    NORMAL_COLUMN,   
    CONSTANT_COLUMN  
  };
 
  Column()               = default;
  Column(const Column &) = delete;
  Column(Column &&)      = delete;
 
  Column(const FieldMeta &meta, size_t size = DEFAULT_CAPACITY);
  Column(AttrType attr_type, int attr_len, size_t size = DEFAULT_CAPACITY);
 
  void init(const FieldMeta &meta, size_t size = DEFAULT_CAPACITY);
  void init(AttrType attr_type, int attr_len, size_t size = DEFAULT_CAPACITY);
  void init(const Value &value);
 
  virtual ~Column() { reset(); }
 
  void reset();
 
  RC append_one(char *data);
 
  RC append(char *data, int count);
 
  Value get_value(int index) const;
 
  int data_len() const { return count_ * attr_len_; }
 
  char *data() const { return data_; }
 
  void reset_data() { count_ = 0; }
 
  void reference(const Column &column);
 
  void set_column_type(Type column_type) { column_type_ = column_type; }
  void set_count(int count) { count_ = count; }
 
  int      count() const { return count_; }
  int      capacity() const { return capacity_; }
  AttrType attr_type() const { return attr_type_; }
  int      attr_len() const { return attr_len_; }
  Type     column_type() const { return column_type_; }
 
private:
  static constexpr size_t DEFAULT_CAPACITY = 8192;
 
  char *data_ = nullptr;
  int count_ = 0;
  int capacity_ = 0;
  bool own_ = true;
  AttrType attr_type_ = AttrType::UNDEFINED;
  int attr_len_ = -1;
  Type column_type_ = Type::NORMAL_COLUMN;
};