test-example-projects/c++_projects/280w-mysql-8.0.18/sql/item_buff.cc

/* Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

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   as designated in a particular file or component or in included license
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   GNU General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

/**
  @file

  @brief
  Buffers to save and compare item values
*/

#include <stddef.h>
#include <algorithm>

#include "my_alloc.h"
#include "my_dbug.h"
#include "my_inttypes.h"
#include "mysql/udf_registration_types.h"
#include "sql/current_thd.h"  // current_thd
#include "sql/item.h"         // Cached_item, ...
#include "sql/json_dom.h"     // Json_wrapper
#include "sql/my_decimal.h"
#include "sql/sql_class.h"  // THD
#include "sql/system_variables.h"
#include "sql/thr_malloc.h"
#include "sql_string.h"
#include "template_utils.h"

using std::max;
using std::min;

/**
  Create right type of Cached_item for an item.
*/

Cached_item *new_Cached_item(THD *thd, Item *item) {
  switch (item->result_type()) {
    case STRING_RESULT:
      if (item->is_temporal())
        return new (thd->mem_root) Cached_item_temporal(item);
      if (item->data_type() == MYSQL_TYPE_JSON)
        return new (thd->mem_root) Cached_item_json(item);
      return new (thd->mem_root) Cached_item_str(thd, item);
    case INT_RESULT:
      return new (thd->mem_root) Cached_item_int(item);
    case REAL_RESULT:
      return new (thd->mem_root) Cached_item_real(item);
    case DECIMAL_RESULT:
      return new (thd->mem_root) Cached_item_decimal(item);
    case ROW_RESULT:
    default:
      DBUG_ASSERT(0);
      return 0;
  }
}

Cached_item::~Cached_item() {}

/**
  Compare with old value and replace value with new value.

  @return
    Return true if values have changed
*/

Cached_item_str::Cached_item_str(THD *thd, Item *arg)
    : Cached_item(arg),
      value_max_length(
          min<uint32>(arg->max_length, thd->variables.max_sort_length)),
      value(value_max_length) {}

bool Cached_item_str::cmp(void) {
  String *res;
  bool tmp;

  DBUG_TRACE;
  DBUG_ASSERT(!item->is_temporal());
  DBUG_ASSERT(item->data_type() != MYSQL_TYPE_JSON);
  if ((res = item->val_str(&tmp_value)))
    res->length(min(res->length(), static_cast<size_t>(value_max_length)));
  DBUG_PRINT("info", ("old: %s, new: %s", value.c_ptr_safe(),
                      res ? res->c_ptr_safe() : ""));
  if (null_value != item->null_value) {
    if ((null_value = item->null_value)) return true;  // New value was null
    tmp = true;
  } else if (null_value)
    return 0;  // new and old value was null
  else
    tmp = sortcmp(&value, res, item->collation.collation) != 0;
  if (tmp) value.copy(*res);  // Remember for next cmp
  return tmp;
}

Cached_item_str::~Cached_item_str() {
  item = 0;  // Safety
}

Cached_item_json::Cached_item_json(Item *item_arg)
    : Cached_item(item_arg), m_value(new (*THR_MALLOC) Json_wrapper()) {}

Cached_item_json::~Cached_item_json() { destroy(m_value); }

/**
  Compare the new JSON value in member 'item' with the previous value.
  @retval true   if the new value is different from the previous value,
                 or if there is no previously cached value
  @retval false  if the new value is the same as the already cached value
*/
bool Cached_item_json::cmp() {
  Json_wrapper wr;
  if (item->val_json(&wr)) {
    null_value = true; /* purecov: inspected */
    return true;       /* purecov: inspected */
  }
  if (null_value != item->null_value) {
    null_value = item->null_value;
    if (null_value) return true;  // New value is null.
  } else if (null_value) {
    return false;  // New and old are null.
  } else if (!m_value->empty() && m_value->compare(wr) == 0) {
    return false;  // New and old are equal.
  }

  /*
    Otherwise, old and new are not equal, and new is not null.
    Remember the current value till the next time we're called.
  */
  *m_value = std::move(wr);

  /*
    The row buffer may change, which would garble the JSON binary
    representation pointed to by m_value. Convert to DOM so that we
    own the copy.
  */
  m_value->to_dom(current_thd);

  return true;
}

void Cached_item_json::copy_to_Item_cache(Item_cache *i_c) {
  down_cast<Item_cache_json *>(i_c)->store_value(item, m_value);
}

bool Cached_item_real::cmp(void) {
  DBUG_TRACE;
  double nr = item->val_real();
  DBUG_PRINT("info", ("old: %f, new: %f", value, nr));
  if (null_value != item->null_value || nr != value) {
    null_value = item->null_value;
    value = nr;
    return true;
  }
  return false;
}

bool Cached_item_int::cmp(void) {
  DBUG_TRACE;
  longlong nr = item->val_int();
  DBUG_PRINT("info", ("old: 0x%.16llx, new: 0x%.16llx", (ulonglong)value,
                      (ulonglong)nr));

  if (null_value != item->null_value || nr != value) {
    null_value = item->null_value;
    value = nr;
    return true;
  }
  return false;
}

bool Cached_item_temporal::cmp(void) {
  DBUG_TRACE;
  longlong nr = item->val_temporal_by_field_type();
  DBUG_PRINT("info", ("old: %lld, new: %lld", value, nr));
  if (null_value != item->null_value || nr != value) {
    null_value = item->null_value;
    value = nr;
    return true;
  }
  return false;
}

Cached_item_decimal::Cached_item_decimal(Item *it) : Cached_item(it) {
  my_decimal_set_zero(&value);
}

void Cached_item_real::copy_to_Item_cache(Item_cache *i_c) {
  down_cast<Item_cache_real *>(i_c)->store_value(item, value);
}

void Cached_item_int::copy_to_Item_cache(Item_cache *i_c) {
  down_cast<Item_cache_int *>(i_c)->store_value(item, value);
}

void Cached_item_temporal::copy_to_Item_cache(Item_cache *i_c) {
  down_cast<Item_cache_datetime *>(i_c)->store_value(item, value);
}

void Cached_item_str::copy_to_Item_cache(Item_cache *i_c) {
  down_cast<Item_cache_str *>(i_c)->store_value(item, value);
}

void Cached_item_decimal::copy_to_Item_cache(Item_cache *i_c) {
  down_cast<Item_cache_decimal *>(i_c)->store_value(item, &value);
}

bool Cached_item_decimal::cmp() {
  my_decimal tmp;
  my_decimal *ptmp = item->val_decimal(&tmp);
  DBUG_TRACE;
  /*
    NULL handling is wrong here, see Bug#25407964 GROUP BY DESC GIVES WRONG
    RESULT WHEN GROUPS ON DECIMAL AND SEES A NULL.
  */
  if (null_value != item->null_value ||
      (!item->null_value && my_decimal_cmp(&value, ptmp))) {
    null_value = item->null_value;
    /* Save only not null values */
    if (!null_value) my_decimal2decimal(ptmp, &value);
    return true;
  }
  return false;
}