~drizzle-trunk/drizzle/development

/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-

 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

 *

 *  Copyright (C) 2008 Sun Microsystems

 *

 *  This program is free software; you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License as published by

 *  the Free Software Foundation; version 2 of the License.

 *

 *  This program is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *  GNU General Public License 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

 */

#include "config.h"

#include <drizzled/function/min_max.h>

#include <drizzled/item/cmpfunc.h>

namespace drizzled

{

void Item_func_min_max::fix_length_and_dec()

{

  int max_int_part=0;

  bool datetime_found= false;

  decimals=0;

  max_length=0;

  maybe_null=0;

  cmp_type=args[0]->result_type();

  for (uint32_t i=0 ; i < arg_count ; i++)

  {

    set_if_bigger(max_length, args[i]->max_length);

    set_if_bigger(decimals, args[i]->decimals);

    set_if_bigger(max_int_part, args[i]->decimal_int_part());

    if (args[i]->maybe_null)

      maybe_null=1;

    cmp_type=item_cmp_type(cmp_type,args[i]->result_type());

    if (args[i]->result_type() != ROW_RESULT && args[i]->is_datetime())

    {

      datetime_found= true;

      if (!datetime_item || args[i]->field_type() == DRIZZLE_TYPE_DATETIME)

        datetime_item= args[i];

    }

  }

  if (cmp_type == STRING_RESULT)

  {

    agg_arg_charsets(collation, args, arg_count, MY_COLL_CMP_CONV, 1);

    if (datetime_found)

    {

      session= getSessionPtr();

      compare_as_dates= true;

    }

  }

  else if ((cmp_type == DECIMAL_RESULT) || (cmp_type == INT_RESULT))

    max_length= my_decimal_precision_to_length(max_int_part+decimals, decimals,

                                            unsigned_flag);

  cached_field_type= agg_field_type(args, arg_count);

}

/*

  Compare item arguments in the DATETIME context.

  SYNOPSIS

    cmp_datetimes()

    value [out]   found least/greatest DATE/DATETIME value

  DESCRIPTION

    Compare item arguments as DATETIME values and return the index of the

    least/greatest argument in the arguments array.

    The correct integer DATE/DATETIME value of the found argument is

    stored to the value pointer, if latter is provided.

  RETURN

   0	If one of arguments is NULL or there was a execution error

   #	index of the least/greatest argument

*/

uint32_t Item_func_min_max::cmp_datetimes(uint64_t *value)

{

  uint64_t min_max= 0;

  uint32_t min_max_idx= 0;

  for (uint32_t i=0; i < arg_count ; i++)

  {

    Item **arg= args + i;

    bool is_null_unused;

    uint64_t res= get_datetime_value(session, &arg, 0, datetime_item,

                                     &is_null_unused);

    /* Check if we need to stop (because of error or KILL)  and stop the loop */

    if (session->is_error())

    {

      null_value= 1;

      return 0;

    }

    if ((null_value= args[i]->null_value))

      return 0;

    if (i == 0 || (res < min_max ? cmp_sign : -cmp_sign) > 0)

    {

      min_max= res;

      min_max_idx= i;

    }

  }

  if (value)

  {

    *value= min_max;

    if (datetime_item->field_type() == DRIZZLE_TYPE_DATE)

      *value/= 1000000L;

  }

  return min_max_idx;

}

String *Item_func_min_max::val_str(String *str)

{

  assert(fixed == 1);

  if (compare_as_dates)

  {

    String *str_res;

    uint32_t min_max_idx= cmp_datetimes(NULL);

    if (null_value)

      return 0;

    str_res= args[min_max_idx]->val_str(str);

    if (args[min_max_idx]->null_value)

    {

      // check if the call to val_str() above returns a NULL value

      null_value= 1;

      return NULL;

    }

    str_res->set_charset(collation.collation);

    return str_res;

  }

  switch (cmp_type) {

  case INT_RESULT:

    {

      int64_t nr=val_int();

      if (null_value)

        return 0;

      str->set_int(nr, unsigned_flag, &my_charset_bin);

      return str;

    }

  case DECIMAL_RESULT:

    {

      my_decimal dec_buf, *dec_val= val_decimal(&dec_buf);

      if (null_value)

        return 0;

      my_decimal2string(E_DEC_FATAL_ERROR, dec_val, 0, 0, 0, str);

      return str;

    }

  case REAL_RESULT:

    {

      double nr= val_real();

      if (null_value)

        return 0;

      str->set_real(nr,decimals,&my_charset_bin);

      return str;

    }

  case STRING_RESULT:

    {

      String *res= NULL;

      for (uint32_t i=0; i < arg_count ; i++)

      {

        if (i == 0)

          res=args[i]->val_str(str);

        else

        {

          String *res2;

          res2= args[i]->val_str(res == str ? &tmp_value : str);

          if (res2)

          {

            int cmp= sortcmp(res,res2,collation.collation);

            if ((cmp_sign < 0 ? cmp : -cmp) < 0)

              res=res2;

          }

        }

        if ((null_value= args[i]->null_value))

          return 0;

      }

      res->set_charset(collation.collation);

      return res;

    }

  case ROW_RESULT:

    // This case should never be chosen

    assert(0);

    return 0;

  }

  return 0;					// Keep compiler happy

}

double Item_func_min_max::val_real()

{

  assert(fixed == 1);

  double value=0.0;

  if (compare_as_dates)

  {

    uint64_t result= 0;

    (void)cmp_datetimes(&result);

    return (double)result;

  }

  for (uint32_t i=0; i < arg_count ; i++)

  {

    if (i == 0)

      value= args[i]->val_real();

    else

    {

      double tmp= args[i]->val_real();

      if (!args[i]->null_value && (tmp < value ? cmp_sign : -cmp_sign) > 0)

	value=tmp;

    }

    if ((null_value= args[i]->null_value))

      break;

  }

  return value;

}

int64_t Item_func_min_max::val_int()

{

  assert(fixed == 1);

  int64_t value=0;

  if (compare_as_dates)

  {

    uint64_t result= 0;

    (void)cmp_datetimes(&result);

    return (int64_t)result;

  }

  for (uint32_t i=0; i < arg_count ; i++)

  {

    if (i == 0)

      value=args[i]->val_int();

    else

    {

      int64_t tmp=args[i]->val_int();

      if (!args[i]->null_value && (tmp < value ? cmp_sign : -cmp_sign) > 0)

	value=tmp;

    }

    if ((null_value= args[i]->null_value))

      break;

  }

  return value;

}

my_decimal *Item_func_min_max::val_decimal(my_decimal *dec)

{

  assert(fixed == 1);

  my_decimal tmp_buf, *tmp, *res= NULL;

  if (compare_as_dates)

  {

    uint64_t value= 0;

    (void)cmp_datetimes(&value);

    uint64_t2decimal(value, dec);

    return dec;

  }

  for (uint32_t i=0; i < arg_count ; i++)

  {

    if (i == 0)

      res= args[i]->val_decimal(dec);

    else

    {

      tmp= args[i]->val_decimal(&tmp_buf);      // Zero if NULL

      if (tmp && (my_decimal_cmp(tmp, res) * cmp_sign) < 0)

      {

        if (tmp == &tmp_buf)

        {

          /* Move value out of tmp_buf as this will be reused on next loop */

          my_decimal2decimal(tmp, dec);

          res= dec;

        }

        else

          res= tmp;

      }

    }

    if ((null_value= args[i]->null_value))

    {

      res= 0;

      break;

    }

  }

  return res;

}

} /* namespace drizzled */