/* Copyright (C) 2000-2003 MySQL AB & MySQL Finland AB & TCX DataKonsult AB

   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; either version 2 of the License, or
   (at your option) any later version.

   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */


/* This file defines all compare functions */

#ifdef __GNUC__
#pragma implementation				// gcc: Class implementation
#endif

#include "mysql_priv.h"
#include <m_ctype.h>
#include "sql_select.h"

static Item_result item_store_type(Item_result a,Item_result b)
{
  if (a == STRING_RESULT || b == STRING_RESULT)
    return STRING_RESULT;
  else if (a == REAL_RESULT || b == REAL_RESULT)
    return REAL_RESULT;
  else
    return INT_RESULT;
}

static void agg_result_type(Item_result *type, Item **items, uint nitems)
{
  uint i;
  type[0]= items[0]->result_type();
  for (i=1 ; i < nitems ; i++)
    type[0]= item_store_type(type[0], items[i]->result_type());
}

static void agg_cmp_type(Item_result *type, Item **items, uint nitems)
{
  uint i;
  type[0]= items[0]->result_type();
  for (i=1 ; i < nitems ; i++)
    type[0]= item_cmp_type(type[0], items[i]->result_type());
}

static void my_coll_agg_error(DTCollation &c1, DTCollation &c2, const char *fname)
{
  my_error(ER_CANT_AGGREGATE_2COLLATIONS,MYF(0),
  	   c1.collation->name,c1.derivation_name(),
	   c2.collation->name,c2.derivation_name(),
	   fname);
}


Item_bool_func2* Eq_creator::create(Item *a, Item *b) const
{
  return new Item_func_eq(a, b);
}


Item_bool_func2* Ne_creator::create(Item *a, Item *b) const
{
  return new Item_func_ne(a, b);
}


Item_bool_func2* Gt_creator::create(Item *a, Item *b) const
{
  return new Item_func_gt(a, b);
}


Item_bool_func2* Lt_creator::create(Item *a, Item *b) const
{
  return new Item_func_lt(a, b);
}


Item_bool_func2* Ge_creator::create(Item *a, Item *b) const
{
  return new Item_func_ge(a, b);
}


Item_bool_func2* Le_creator::create(Item *a, Item *b) const
{
  return new Item_func_le(a, b);
}

/*
  Test functions
  Most of these  returns 0LL if false and 1LL if true and
  NULL if some arg is NULL.
*/

longlong Item_func_not::val_int()
{
  double value=args[0]->val();
  null_value=args[0]->null_value;
  return !null_value && value == 0 ? 1 : 0;
}

/*
  special NOT for ALL subquery
*/

longlong Item_func_not_all::val_int()
{  
  double value= args[0]->val();
  if (abort_on_null)
  {
    null_value= 0;
    return (args[0]->null_value || value == 0) ? 1 : 0;
  }
  null_value= args[0]->null_value;
  return (!null_value && value == 0) ? 1 : 0;
}

void Item_func_not_all::print(String *str)
{
  if (show)
    Item_func::print(str);
  else
    args[0]->print(str);
}

/*
  Convert a constant expression or string to an integer.
  This is done when comparing DATE's of different formats and
  also when comparing bigint to strings (in which case the string
  is converted once to a bigint).

  RESULT VALUES
  0	Can't convert item
  1	Item was replaced with an integer version of the item
*/

static bool convert_constant_item(Field *field, Item **item)
{
  if ((*item)->const_item())
  {
    if (!(*item)->save_in_field(field, 1) && !((*item)->null_value))
    {
      Item *tmp=new Item_int_with_ref(field->val_int(), *item);
      if (tmp)
	*item=tmp;
      return 1;					// Item was replaced
    }
  }
  return 0;
}


void Item_bool_func2::fix_length_and_dec()
{
  max_length= 1;				     // Function returns 0 or 1

  /*
    As some compare functions are generated after sql_yacc,
    we have to check for out of memory conditions here
  */
  if (!args[0] || !args[1])
    return;

  /* 
    We allow to convert to Unicode character sets in some cases.
    The conditions when conversion is possible are:
    - arguments A and B have different charsets
    - A wins according to coercibility rules
    - character set of A is superset for character set of B
   
    If all of the above is true, then it's possible to convert
    B into the character set of A, and then compare according
    to the collation of A.
  */

  if (args[0] && args[1])
  {
    uint strong= 0;
    uint weak= 0;

    if ((args[0]->collation.derivation < args[1]->collation.derivation) && 
	!my_charset_same(args[0]->collation.collation, 
			 args[1]->collation.collation) &&
        (args[0]->collation.collation->state & MY_CS_UNICODE))
    {
      weak= 1;
    }
    else if ((args[1]->collation.derivation < args[0]->collation.derivation) && 
	     !my_charset_same(args[0]->collation.collation,
			      args[1]->collation.collation) &&
             (args[1]->collation.collation->state & MY_CS_UNICODE))
    {
      strong= 1;
    }
    
    if (strong || weak)
    {
      Item* conv= 0;
      if (args[weak]->type() == STRING_ITEM)
      {
        String tmp, cstr;
        String *ostr= args[weak]->val_str(&tmp);
        cstr.copy(ostr->ptr(), ostr->length(), ostr->charset(), 
		  args[strong]->collation.collation);
        conv= new Item_string(cstr.ptr(),cstr.length(),cstr.charset(),
			      args[weak]->collation.derivation);
	((Item_string*)conv)->str_value.copy();
      }
      else
      {
	conv= new Item_func_conv_charset(args[weak],args[strong]->collation.collation);
        conv->collation.set(args[weak]->collation.derivation);
      }
      args[weak]= conv ? conv : args[weak];
    }
  }
  
  // Make a special case of compare with fields to get nicer DATE comparisons
  if (args[0]->type() == FIELD_ITEM)
  {
    Field *field=((Item_field*) args[0])->field;
    if (field->store_for_compare())
    {
      if (convert_constant_item(field,&args[1]))
      {
	cmp.set_cmp_func(this, tmp_arg, tmp_arg+1,
			 INT_RESULT);		// Works for all types.
	return;
      }
    }
  }
  if (args[1]->type() == FIELD_ITEM)
  {
    Field *field=((Item_field*) args[1])->field;
    if (field->store_for_compare())
    {
      if (convert_constant_item(field,&args[0]))
      {
	cmp.set_cmp_func(this, tmp_arg, tmp_arg+1,
			 INT_RESULT); // Works for all types.
	return;
      }
    }
  }
  set_cmp_func();
}


int Arg_comparator::set_compare_func(Item_bool_func2 *item, Item_result type)
{
  owner= item;
  func= comparator_matrix[type][(owner->functype() == Item_func::EQUAL_FUNC)?
				1:0];
  if (type == ROW_RESULT)
  {
    uint n= (*a)->cols();
    if (n != (*b)->cols())
    {
      my_error(ER_OPERAND_COLUMNS, MYF(0), n);
      comparators= 0;
      return 1;
    }
    if (!(comparators= (Arg_comparator *) sql_alloc(sizeof(Arg_comparator)*n)))
      return 1;
    for (uint i=0; i < n; i++)
    {
      if ((*a)->el(i)->cols() != (*b)->el(i)->cols())
      {
	my_error(ER_OPERAND_COLUMNS, MYF(0), (*a)->el(i)->cols());
	return 1;
      }
      comparators[i].set_cmp_func(owner, (*a)->addr(i), (*b)->addr(i));
    }
  }
  else if (type == STRING_RESULT)
  {
    /*
      We must set cmp_charset here as we may be called from for an automatic
      generated item, like in natural join
    */
    if (cmp_collation.set((*a)->collation, (*b)->collation) || 
	cmp_collation.derivation == DERIVATION_NONE)
    {
      my_coll_agg_error((*a)->collation, (*b)->collation, owner->func_name());
      return 1;
    }
  }
  return 0;
}


int Arg_comparator::compare_string()
{
  String *res1,*res2;
  if ((res1= (*a)->val_str(&owner->tmp_value1)))
  {
    if ((res2= (*b)->val_str(&owner->tmp_value2)))
    {
      owner->null_value= 0;
      return sortcmp(res1,res2,cmp_collation.collation);
    }
  }
  owner->null_value= 1;
  return -1;
}

int Arg_comparator::compare_e_string()
{
  String *res1,*res2;
  res1= (*a)->val_str(&owner->tmp_value1);
  res2= (*b)->val_str(&owner->tmp_value2);
  if (!res1 || !res2)
    return test(res1 == res2);
  return test(sortcmp(res1, res2, cmp_collation.collation) == 0);
}


int Arg_comparator::compare_real()
{
  double val1= (*a)->val();
  if (!(*a)->null_value)
  {
    double val2= (*b)->val();
    if (!(*b)->null_value)
    {
      owner->null_value= 0;
      if (val1 < val2)	return -1;
      if (val1 == val2) return 0;
      return 1;
    }
  }
  owner->null_value= 1;
  return -1;
}

int Arg_comparator::compare_e_real()
{
  double val1= (*a)->val();
  double val2= (*b)->val();
  if ((*a)->null_value || (*b)->null_value)
    return test((*a)->null_value && (*b)->null_value);
  return test(val1 == val2);
}

int Arg_comparator::compare_int()
{
  longlong val1= (*a)->val_int();
  if (!(*a)->null_value)
  {
    longlong val2= (*b)->val_int();
    if (!(*b)->null_value)
    {
      owner->null_value= 0;
      if (val1 < val2)	return -1;
      if (val1 == val2)   return 0;
      return 1;
    }
  }
  owner->null_value= 1;
  return -1;
}

int Arg_comparator::compare_e_int()
{
  longlong val1= (*a)->val_int();
  longlong val2= (*b)->val_int();
  if ((*a)->null_value || (*b)->null_value)
    return test((*a)->null_value && (*b)->null_value);
  return test(val1 == val2);
}


int Arg_comparator::compare_row()
{
  int res= 0;
  (*a)->bring_value();
  (*b)->bring_value();
  uint n= (*a)->cols();
  for (uint i= 0; i<n; i++)
  {
    if ((res= comparators[i].compare()))
      return res;
    if (owner->null_value)
      return -1;
  }
  return res;
}

int Arg_comparator::compare_e_row()
{
  (*a)->bring_value();
  (*b)->bring_value();
  uint n= (*a)->cols();
  for (uint i= 0; i<n; i++)
  {
    if (!comparators[i].compare())
      return 0;
  }
  return 1;
}


bool Item_in_optimizer::fix_left(THD *thd,
				 struct st_table_list *tables,
				 Item **ref)
{
  if (args[0]->fix_fields(thd, tables, ref) ||
      (!cache && !(cache= Item_cache::get_cache(args[0]->result_type()))))
    return 1;
  cache->setup(args[0]);
  cache->store(args[0]);
  if (cache->cols() == 1)
  {
    if ((used_tables_cache= args[0]->used_tables()))
      cache->set_used_tables(OUTER_REF_TABLE_BIT);
    else
      cache->set_used_tables(0);
  }
  else
  {
    uint n= cache->cols();
    for (uint i= 0; i < n; i++)
    {
      if (args[0]->el(i)->used_tables())
	((Item_cache *)cache->el(i))->set_used_tables(OUTER_REF_TABLE_BIT);
      else
	((Item_cache *)cache->el(i))->set_used_tables(0);
    }
    used_tables_cache= args[0]->used_tables();
  }
  not_null_tables_cache= args[0]->not_null_tables();
  with_sum_func= args[0]->with_sum_func;
  const_item_cache= args[0]->const_item();
  fixed= 1;
  return 0;
}



bool Item_in_optimizer::fix_fields(THD *thd, struct st_table_list *tables,
				   Item ** ref)
{
  if (fix_left(thd, tables, ref))
    return 1;
  if (args[0]->maybe_null)
    maybe_null=1;

  if (!args[1]->fixed && args[1]->fix_fields(thd, tables, args))
    return 1;
  Item_in_subselect * sub= (Item_in_subselect *)args[1];
  if (args[0]->cols() != sub->engine->cols())
  {
    my_error(ER_OPERAND_COLUMNS, MYF(0), args[0]->cols());
    return 1;
  }
  if (args[1]->maybe_null)
    maybe_null=1;
  with_sum_func= with_sum_func || args[1]->with_sum_func;
  used_tables_cache|= args[1]->used_tables();
  not_null_tables_cache|= args[1]->not_null_tables();
  const_item_cache&= args[1]->const_item();
  return 0;
}

longlong Item_in_optimizer::val_int()
{
  cache->store(args[0]);
  if (cache->null_value)
  {
    null_value= 1;
    return 0;
  }
  longlong tmp= args[1]->val_int_result();
  null_value= args[1]->null_value;
  return tmp;
}

bool Item_in_optimizer::is_null()
{
  cache->store(args[0]);
  return (null_value= (cache->null_value || args[1]->is_null()));
}

longlong Item_func_eq::val_int()
{
  int value= cmp.compare();
  return value == 0 ? 1 : 0;
}


/* Same as Item_func_eq, but NULL = NULL */

void Item_func_equal::fix_length_and_dec()
{
  Item_bool_func2::fix_length_and_dec();
  maybe_null=null_value=0;
}

longlong Item_func_equal::val_int()
{
  return cmp.compare();
}

longlong Item_func_ne::val_int()
{
  int value= cmp.compare();
  return value != 0 && !null_value ? 1 : 0;
}


longlong Item_func_ge::val_int()
{
  int value= cmp.compare();
  return value >= 0 ? 1 : 0;
}


longlong Item_func_gt::val_int()
{
  int value= cmp.compare();
  return value > 0 ? 1 : 0;
}

longlong Item_func_le::val_int()
{
  int value= cmp.compare();
  return value <= 0 && !null_value ? 1 : 0;
}


longlong Item_func_lt::val_int()
{
  int value= cmp.compare();
  return value < 0 && !null_value ? 1 : 0;
}


longlong Item_func_strcmp::val_int()
{
  String *a=args[0]->val_str(&tmp_value1);
  String *b=args[1]->val_str(&tmp_value2);
  if (!a || !b)
  {
    null_value=1;
    return 0;
  }
  int value= sortcmp(a,b,cmp.cmp_collation.collation);
  null_value=0;
  return !value ? 0 : (value < 0 ? (longlong) -1 : (longlong) 1);
}


void Item_func_interval::fix_length_and_dec()
{
  if (row->cols() > 8)
  {
    bool consts=1;

    for (uint i=1 ; consts && i < row->cols() ; i++)
    {
      consts&= row->el(i)->const_item();
    }

    if (consts &&
        (intervals=(double*) sql_alloc(sizeof(double)*(row->cols()-1))))
    {
      for (uint i=1 ; i < row->cols(); i++)
        intervals[i-1]=row->el(i)->val();
    }
  }
  maybe_null= 0;
  max_length= 2;
  used_tables_cache|= row->used_tables();
  not_null_tables_cache&= row->not_null_tables();
  with_sum_func= with_sum_func || row->with_sum_func;
  const_item_cache&= row->const_item();
}


/*
  return -1 if null value,
	  0 if lower than lowest
	  1 - arg_count-1 if between args[n] and args[n+1]
	  arg_count if higher than biggest argument
*/

longlong Item_func_interval::val_int()
{
  double value= row->el(0)->val();
  uint i;

  if (row->el(0)->null_value)
    return -1;				// -1 if null
  if (intervals)
  {					// Use binary search to find interval
    uint start,end;
    start= 1;
    end=   row->cols()-2;
    while (start != end)
    {
      uint mid= (start + end + 1) / 2;
      if (intervals[mid] <= value)
	start= mid;
      else
	end= mid - 1;
    }
    return (value < intervals[start]) ? 0 : start + 1;
  }

  for (i=1 ; i < row->cols() ; i++)
  {
    if (row->el(i)->val() > value)
      return i-1;
  }
  return i-1;
}

void Item_func_between::fix_length_and_dec()
{
   max_length= 1;

  /*
    As some compare functions are generated after sql_yacc,
    we have to check for out of memory conditons here
  */
  if (!args[0] || !args[1] || !args[2])
    return;
  agg_cmp_type(&cmp_type, args, 3);
  if (cmp_type == STRING_RESULT &&
      agg_arg_collations_for_comparison(cmp_collation, args, 3))
    return;

  /*
    Make a special case of compare with date/time and longlong fields.
    They are compared as integers, so for const item this time-consuming
    conversion can be done only once, not for every single comparison
  */
  if (args[0]->type() == FIELD_ITEM)
  {
    Field *field=((Item_field*) args[0])->field;
    if (field->store_for_compare())
    {
      if (convert_constant_item(field,&args[1]))
	cmp_type=INT_RESULT;			// Works for all types.
      if (convert_constant_item(field,&args[2]))
	cmp_type=INT_RESULT;			// Works for all types.
    }
  }
}


longlong Item_func_between::val_int()
{						// ANSI BETWEEN
  if (cmp_type == STRING_RESULT)
  {
    String *value,*a,*b;
    value=args[0]->val_str(&value0);
    if ((null_value=args[0]->null_value))
      return 0;
    a=args[1]->val_str(&value1);
    b=args[2]->val_str(&value2);
    if (!args[1]->null_value && !args[2]->null_value)
      return (sortcmp(value,a,cmp_collation.collation) >= 0 && 
	      sortcmp(value,b,cmp_collation.collation) <= 0) ? 1 : 0;
    if (args[1]->null_value && args[2]->null_value)
      null_value=1;
    else if (args[1]->null_value)
    {
      null_value= sortcmp(value,b,cmp_collation.collation) <= 0; // not null if false range.
    }
    else
    {
      null_value= sortcmp(value,a,cmp_collation.collation) >= 0; // not null if false range.
    }
  }
  else if (cmp_type == INT_RESULT)
  {
    longlong value=args[0]->val_int(),a,b;
    if ((null_value=args[0]->null_value))
      return 0;					/* purecov: inspected */
    a=args[1]->val_int();
    b=args[2]->val_int();
    if (!args[1]->null_value && !args[2]->null_value)
      return (value >= a && value <= b) ? 1 : 0;
    if (args[1]->null_value && args[2]->null_value)
      null_value=1;
    else if (args[1]->null_value)
    {
      null_value= value <= b;			// not null if false range.
    }
    else
    {
      null_value= value >= a;
    }
  }
  else
  {
    double value=args[0]->val(),a,b;
    if ((null_value=args[0]->null_value))
      return 0;					/* purecov: inspected */
    a=args[1]->val();
    b=args[2]->val();
    if (!args[1]->null_value && !args[2]->null_value)
      return (value >= a && value <= b) ? 1 : 0;
    if (args[1]->null_value && args[2]->null_value)
      null_value=1;
    else if (args[1]->null_value)
    {
      null_value= value <= b;			// not null if false range.
    }
    else
    {
      null_value= value >= a;
    }
  }
  return 0;
}


void Item_func_between::print(String *str)
{
  str->append('(');
  args[0]->print(str);
  str->append(" between ", 9);
  args[1]->print(str);
  str->append(" and ", 5);
  args[2]->print(str);
  str->append(')');
}

void
Item_func_ifnull::fix_length_and_dec()
{
  maybe_null=args[1]->maybe_null;
  max_length=max(args[0]->max_length,args[1]->max_length);
  decimals=max(args[0]->decimals,args[1]->decimals);
  agg_result_type(&cached_result_type, args, 2);
  if (cached_result_type == STRING_RESULT)
    agg_arg_collations(collation, args, arg_count);
  else if (cached_result_type != REAL_RESULT)
    decimals= 0;
  
  cached_field_type= args[0]->field_type();
  if (cached_field_type != args[1]->field_type())
    cached_field_type= Item_func::field_type();
}

enum_field_types Item_func_ifnull::field_type() const 
{
  return cached_field_type;
}

Field *Item_func_ifnull::tmp_table_field(TABLE *table)
{
  return tmp_table_field_from_field_type(table);
}

double
Item_func_ifnull::val()
{
  double value=args[0]->val();
  if (!args[0]->null_value)
  {
    null_value=0;
    return value;
  }
  value=args[1]->val();
  if ((null_value=args[1]->null_value))
    return 0.0;
  return value;
}

longlong
Item_func_ifnull::val_int()
{
  longlong value=args[0]->val_int();
  if (!args[0]->null_value)
  {
    null_value=0;
    return value;
  }
  value=args[1]->val_int();
  if ((null_value=args[1]->null_value))
    return 0;
  return value;
}

String *
Item_func_ifnull::val_str(String *str)
{
  String *res  =args[0]->val_str(str);
  if (!args[0]->null_value)
  {
    null_value=0;
    res->set_charset(collation.collation);
    return res;
  }
  res=args[1]->val_str(str);
  if ((null_value=args[1]->null_value))
    return 0;
  res->set_charset(collation.collation);
  return res;
}


void
Item_func_if::fix_length_and_dec()
{
  maybe_null=args[1]->maybe_null || args[2]->maybe_null;
  max_length=max(args[1]->max_length,args[2]->max_length);
  decimals=max(args[1]->decimals,args[2]->decimals);
  enum Item_result arg1_type=args[1]->result_type();
  enum Item_result arg2_type=args[2]->result_type();
  bool null1=args[1]->null_value;
  bool null2=args[2]->null_value;

  if (null1)
  {
    cached_result_type= arg2_type;
    collation.set(args[2]->collation.collation);
  }
  else if (null2)
  {
    cached_result_type= arg1_type;
    collation.set(args[1]->collation.collation);
  }
  else
  {
    agg_result_type(&cached_result_type, args+1, 2);
    if (cached_result_type == STRING_RESULT)
    {
      if (agg_arg_collations(collation, args+1, 2))
      return;
    }
    else
    {
      collation.set(&my_charset_bin);	// Number
    }
  }
}


double
Item_func_if::val()
{
  Item *arg= args[0]->val_int() ? args[1] : args[2];
  double value=arg->val();
  null_value=arg->null_value;
  return value;
}

longlong
Item_func_if::val_int()
{
  Item *arg= args[0]->val_int() ? args[1] : args[2];
  longlong value=arg->val_int();
  null_value=arg->null_value;
  return value;
}

String *
Item_func_if::val_str(String *str)
{
  Item *arg= args[0]->val_int() ? args[1] : args[2];
  String *res=arg->val_str(str);
  if (res)
    res->set_charset(collation.collation);
  null_value=arg->null_value;
  return res;
}


void
Item_func_nullif::fix_length_and_dec()
{
  Item_bool_func2::fix_length_and_dec();
  maybe_null=1;
  if (args[0])					// Only false if EOM
  {
    max_length=args[0]->max_length;
    decimals=args[0]->decimals;
    agg_result_type(&cached_result_type, args, 2);
  }
}

/*
  nullif () returns NULL if arguments are equal, else it returns the
  first argument.
  Note that we have to evaluate the first argument twice as the compare
  may have been done with a different type than return value
*/

double
Item_func_nullif::val()
{
  double value;
  if (!cmp.compare() || null_value)
  {
    null_value=1;
    return 0.0;
  }
  value=args[0]->val();
  null_value=args[0]->null_value;
  return value;
}

longlong
Item_func_nullif::val_int()
{
  longlong value;
  if (!cmp.compare() || null_value)
  {
    null_value=1;
    return 0;
  }
  value=args[0]->val_int();
  null_value=args[0]->null_value;
  return value;
}

String *
Item_func_nullif::val_str(String *str)
{
  String *res;
  if (!cmp.compare() || null_value)
  {
    null_value=1;
    return 0;
  }
  res=args[0]->val_str(str);
  null_value=args[0]->null_value;
  return res;
}

/*
  CASE expression 
  Return the matching ITEM or NULL if all compares (including else) failed
*/

Item *Item_func_case::find_item(String *str)
{
  String *first_expr_str,*tmp;
  longlong first_expr_int;
  double   first_expr_real;
  
  /* These will be initialized later */
  LINT_INIT(first_expr_str);
  LINT_INIT(first_expr_int);
  LINT_INIT(first_expr_real);

  if (first_expr_num != -1)
  {
    switch (cmp_type)
    {
      case STRING_RESULT:
      	// We can't use 'str' here as this may be overwritten
	if (!(first_expr_str= args[first_expr_num]->val_str(&str_value)))
	  return else_expr_num != -1 ? args[else_expr_num] : 0;	// Impossible
        break;
      case INT_RESULT:
	first_expr_int= args[first_expr_num]->val_int();
	if (args[first_expr_num]->null_value)
	  return else_expr_num != -1 ? args[else_expr_num] : 0;
	break;
      case REAL_RESULT:
	first_expr_real= args[first_expr_num]->val();
	if (args[first_expr_num]->null_value)
	  return else_expr_num != -1 ? args[else_expr_num] : 0;
	break;
      case ROW_RESULT:
      default:
	// This case should never be choosen
	DBUG_ASSERT(0);
	break;
    }
  }

  // Compare every WHEN argument with it and return the first match
  for (uint i=0 ; i < ncases ; i+=2)
  {
    if (first_expr_num == -1)
    {
      // No expression between CASE and the first WHEN
      if (args[i]->val_int())
	return args[i+1];
      continue;
    }
    switch (cmp_type) {
    case STRING_RESULT:
      if ((tmp=args[i]->val_str(str)))		// If not null
	if (sortcmp(tmp,first_expr_str,cmp_collation.collation)==0)
	  return args[i+1];
      break;
    case INT_RESULT:
      if (args[i]->val_int()==first_expr_int && !args[i]->null_value) 
        return args[i+1];
      break;
    case REAL_RESULT: 
      if (args[i]->val()==first_expr_real && !args[i]->null_value) 
        return args[i+1];
      break;
    case ROW_RESULT:
    default:
      // This case should never be choosen
      DBUG_ASSERT(0);
      break;
    }
  }
  // No, WHEN clauses all missed, return ELSE expression
  return else_expr_num != -1 ? args[else_expr_num] : 0;
}



String *Item_func_case::val_str(String *str)
{
  String *res;
  Item *item=find_item(str);

  if (!item)
  {
    null_value=1;
    return 0;
  }
  null_value= 0;
  if (!(res=item->val_str(str)))
    null_value= 1;
  return res;
}


longlong Item_func_case::val_int()
{
  char buff[MAX_FIELD_WIDTH];
  String dummy_str(buff,sizeof(buff),default_charset());
  Item *item=find_item(&dummy_str);
  longlong res;

  if (!item)
  {
    null_value=1;
    return 0;
  }
  res=item->val_int();
  null_value=item->null_value;
  return res;
}

double Item_func_case::val()
{
  char buff[MAX_FIELD_WIDTH];
  String dummy_str(buff,sizeof(buff),default_charset());
  Item *item=find_item(&dummy_str);
  double res;

  if (!item)
  {
    null_value=1;
    return 0;
  }
  res=item->val();
  null_value=item->null_value;
  return res;
}

void Item_func_case::fix_length_and_dec()
{
  Item **agg;
  uint nagg;
  
  if (!(agg= (Item**) sql_alloc(sizeof(Item*)*(ncases+1))))
    return;
  
  // Aggregate all THEN and ELSE expression types
  // and collations when string result
  
  for (nagg= 0 ; nagg < ncases/2 ; nagg++)
    agg[nagg]= args[nagg*2+1];
  
  if (else_expr_num != -1)
    agg[nagg++]= args[else_expr_num];
  
  agg_result_type(&cached_result_type, agg, nagg);
  if ((cached_result_type == STRING_RESULT) &&
      agg_arg_collations(collation, agg, nagg))
    return;
  
  
  /*
    Aggregate first expression and all THEN expression types
    and collations when string comparison
  */
  if (first_expr_num != -1)
  {
    agg[0]= args[first_expr_num];
    for (nagg= 0; nagg < ncases/2 ; nagg++)
      agg[nagg+1]= args[nagg*2];
    nagg++;
    agg_cmp_type(&cmp_type, agg, nagg);
    if ((cmp_type == STRING_RESULT) &&
        agg_arg_collations_for_comparison(cmp_collation, agg, nagg))
    return;
  }
  
  if (else_expr_num == -1 || args[else_expr_num]->maybe_null)
    maybe_null=1;
  
  max_length=0;
  decimals=0;
  for (uint i=0 ; i < ncases ; i+=2)
  {
    set_if_bigger(max_length,args[i+1]->max_length);
    set_if_bigger(decimals,args[i+1]->decimals);
  }
  if (else_expr_num != -1) 
  {
    set_if_bigger(max_length,args[else_expr_num]->max_length);
    set_if_bigger(decimals,args[else_expr_num]->decimals);
  }
}


/* TODO:  Fix this so that it prints the whole CASE expression */

void Item_func_case::print(String *str)
{
  str->append("(case ", 6);
  if (first_expr_num != -1)
  {
    args[first_expr_num]->print(str);
    str->append(' ');
  }
  for (uint i=0 ; i < ncases ; i+=2)
  {
    str->append("when ", 5);
    args[i]->print(str);
    str->append(" then ", 6);
    args[i+1]->print(str);
    str->append(' ');
  }
  if (else_expr_num != -1)
  {
    str->append("else ", 5);
    args[else_expr_num]->print(str);
    str->append(' ');
  }
  str->append("end)", 4);
}

/*
  Coalesce - return first not NULL argument.
*/

String *Item_func_coalesce::val_str(String *str)
{
  null_value=0;
  for (uint i=0 ; i < arg_count ; i++)
  {
    String *res;
    if ((res=args[i]->val_str(str)))
      return res;
  }
  null_value=1;
  return 0;
}

longlong Item_func_coalesce::val_int()
{
  null_value=0;
  for (uint i=0 ; i < arg_count ; i++)
  {
    longlong res=args[i]->val_int();
    if (!args[i]->null_value)
      return res;
  }
  null_value=1;
  return 0;
}

double Item_func_coalesce::val()
{
  null_value=0;
  for (uint i=0 ; i < arg_count ; i++)
  {
    double res=args[i]->val();
    if (!args[i]->null_value)
      return res;
  }
  null_value=1;
  return 0;
}


void Item_func_coalesce::fix_length_and_dec()
{
  max_length= 0;
  decimals= 0;
  agg_result_type(&cached_result_type, args, arg_count);
  for (uint i=0 ; i < arg_count ; i++)
  {
    set_if_bigger(max_length,args[i]->max_length);
    set_if_bigger(decimals,args[i]->decimals);
  }
  if (cached_result_type == STRING_RESULT)
    agg_arg_collations(collation, args, arg_count);
  else if (cached_result_type != REAL_RESULT)
    decimals= 0;
}

/****************************************************************************
 Classes and function for the IN operator
****************************************************************************/

static int cmp_longlong(void *cmp_arg, longlong *a,longlong *b)
{
  return *a < *b ? -1 : *a == *b ? 0 : 1;
}

static int cmp_double(void *cmp_arg, double *a,double *b)
{
  return *a < *b ? -1 : *a == *b ? 0 : 1;
}

static int cmp_row(void *cmp_arg, cmp_item_row* a, cmp_item_row* b)
{
  return a->compare(b);
}

int in_vector::find(Item *item)
{
  byte *result=get_value(item);
  if (!result || !used_count)
    return 0;				// Null value

  uint start,end;
  start=0; end=used_count-1;
  while (start != end)
  {
    uint mid=(start+end+1)/2;
    int res;
    if ((res=(*compare)(collation, base+mid*size, result)) == 0)
      return 1;
    if (res < 0)
      start=mid;
    else
      end=mid-1;
  }
  return (int) ((*compare)(collation, base+start*size, result) == 0);
}

in_string::in_string(uint elements,qsort2_cmp cmp_func, CHARSET_INFO *cs)
  :in_vector(elements, sizeof(String), cmp_func, cs),
   tmp(buff, sizeof(buff), &my_charset_bin)
{}

in_string::~in_string()
{
  if (base)
  {
    // base was allocated with help of sql_alloc => following is OK
    for (uint i=0 ; i < count ; i++)
      ((String*) base)[i].free();
  }
}

void in_string::set(uint pos,Item *item)
{
  String *str=((String*) base)+pos;
  String *res=item->val_str(str);
  if (res && res != str)
    *str= *res;
  if (!str->charset())
  {
    CHARSET_INFO *cs;
    if (!(cs= item->collation.collation))
      cs= &my_charset_bin;		// Should never happen for STR items
    str->set_charset(cs);
  }
}


byte *in_string::get_value(Item *item)
{
  return (byte*) item->val_str(&tmp);
}

in_row::in_row(uint elements, Item * item)
{
  base= (char*) new cmp_item_row[count= elements];
  size= sizeof(cmp_item_row);
  compare= (qsort2_cmp) cmp_row;
  tmp.store_value(item);
}

in_row::~in_row()
{
  if (base)
    delete [] (cmp_item_row*) base;
}

byte *in_row::get_value(Item *item)
{
  tmp.store_value(item);
  return (byte *)&tmp;
}

void in_row::set(uint pos, Item *item)
{
  DBUG_ENTER("in_row::set");
  DBUG_PRINT("enter", ("pos %u item 0x%lx", pos, (ulong) item));
  ((cmp_item_row*) base)[pos].store_value_by_template(&tmp, item);
  DBUG_VOID_RETURN;
}

in_longlong::in_longlong(uint elements)
  :in_vector(elements,sizeof(longlong),(qsort2_cmp) cmp_longlong, 0)
{}

void in_longlong::set(uint pos,Item *item)
{
  ((longlong*) base)[pos]=item->val_int();
}

byte *in_longlong::get_value(Item *item)
{
  tmp= item->val_int();
  if (item->null_value)
    return 0;
  return (byte*) &tmp;
}

in_double::in_double(uint elements)
  :in_vector(elements,sizeof(double),(qsort2_cmp) cmp_double, 0)
{}

void in_double::set(uint pos,Item *item)
{
  ((double*) base)[pos]=item->val();
}

byte *in_double::get_value(Item *item)
{
  tmp= item->val();
  if (item->null_value)
    return 0;					/* purecov: inspected */
  return (byte*) &tmp;
}

cmp_item* cmp_item::get_comparator(Item *item)
{
  switch (item->result_type()) {
  case STRING_RESULT:
    return new cmp_item_sort_string(item->collation.collation);
    break;
  case INT_RESULT:
    return new cmp_item_int;
    break;
  case REAL_RESULT:
    return new cmp_item_real;
    break;
  case ROW_RESULT:
    return new cmp_item_row;
    break;
  default:
    DBUG_ASSERT(0);
    break;
  }
  return 0; // to satisfy compiler :)
}


cmp_item* cmp_item_sort_string::make_same()
{
  return new cmp_item_sort_string_in_static(cmp_charset);
}

cmp_item* cmp_item_int::make_same()
{
  return new cmp_item_int();
}

cmp_item* cmp_item_real::make_same()
{
  return new cmp_item_real();
}

cmp_item* cmp_item_row::make_same()
{
  return new cmp_item_row();
}


cmp_item_row::~cmp_item_row()
{
  DBUG_ENTER("~cmp_item_row");
  DBUG_PRINT("enter",("this: %lx", this));
  if (comparators)
  {
    for (uint i= 0; i < n; i++)
    {
      if (comparators[i])
	delete comparators[i];
    }
  }
  DBUG_VOID_RETURN;
}


void cmp_item_row::store_value(Item *item)
{
  DBUG_ENTER("cmp_item_row::store_value");
  n= item->cols();
  if (!comparators)
    comparators= (cmp_item **) current_thd->calloc(sizeof(cmp_item *)*n);
  if (comparators)
  {
    item->bring_value();
    item->null_value= 0;
    for (uint i=0; i < n; i++)
    {
      if (!comparators[i])
	if (!(comparators[i]= cmp_item::get_comparator(item->el(i))))
	  break;					// new failed
      comparators[i]->store_value(item->el(i));
      item->null_value|= item->el(i)->null_value;
    }
  }
  DBUG_VOID_RETURN;
}


void cmp_item_row::store_value_by_template(cmp_item *t, Item *item)
{
  cmp_item_row *tmpl= (cmp_item_row*) t;
  if (tmpl->n != item->cols())
  {
    my_error(ER_OPERAND_COLUMNS, MYF(0), tmpl->n);
    return;
  }
  n= tmpl->n;
  if ((comparators= (cmp_item **) sql_alloc(sizeof(cmp_item *)*n)))
  {
    item->bring_value();
    item->null_value= 0;
    for (uint i=0; i < n; i++)
    {
      if (!(comparators[i]= tmpl->comparators[i]->make_same()))
	break;					// new failed
      comparators[i]->store_value_by_template(tmpl->comparators[i],
					      item->el(i));
      item->null_value|= item->el(i)->null_value;
    }
  }
}


int cmp_item_row::cmp(Item *arg)
{
  arg->null_value= 0;
  if (arg->cols() != n)
  {
    my_error(ER_OPERAND_COLUMNS, MYF(0), n);
    return 1;
  }
  bool was_null= 0;
  arg->bring_value();
  for (uint i=0; i < n; i++)
  {
    if (comparators[i]->cmp(arg->el(i)))
    {
      if (!arg->el(i)->null_value)
	return 1;
      was_null= 1;
    }
  }
  return (arg->null_value= was_null);
}


int cmp_item_row::compare(cmp_item *c)
{
  cmp_item_row *cmp= (cmp_item_row *) c;
  for (uint i=0; i < n; i++)
  {
    int res;
    if ((res= comparators[i]->compare(cmp->comparators[i])))
      return res;
  }
  return 0;
}


bool Item_func_in::nulls_in_row()
{
  Item **arg,**arg_end;
  for (arg= args+1, arg_end= args+arg_count; arg != arg_end ; arg++)
  {
    if ((*arg)->null_inside())
      return 1;
  }
  return 0;
}


static int srtcmp_in(CHARSET_INFO *cs, const String *x,const String *y)
{
  return cs->coll->strnncollsp(cs,
                        (unsigned char *) x->ptr(),x->length(),
			(unsigned char *) y->ptr(),y->length());
}


void Item_func_in::fix_length_and_dec()
{
  Item **arg, **arg_end;
  uint const_itm= 1;
  
  agg_cmp_type(&cmp_type, args, arg_count);
  if ((cmp_type == STRING_RESULT) &&
      (agg_arg_collations_for_comparison(cmp_collation, args, arg_count)))
    return;
  
  for (arg=args+1, arg_end=args+arg_count; arg != arg_end ; arg++)
    const_itm&= arg[0]->const_item();
  
  /*
    Row item with NULLs inside can return NULL or FALSE => 
    they can't be processed as static
  */
  if (const_itm && !nulls_in_row())
  {
    switch (cmp_type) {
    case STRING_RESULT:
      array=new in_string(arg_count-1,(qsort2_cmp) srtcmp_in, 
			  cmp_collation.collation);
      break;
    case INT_RESULT:
      array= new in_longlong(arg_count-1);
      break;
    case REAL_RESULT:
      array= new in_double(arg_count-1);
      break;
    case ROW_RESULT:
      array= new in_row(arg_count-1, args[0]);
      break;
    default:
      DBUG_ASSERT(0);
      return;
    }
    if (array && !(current_thd->is_fatal_error))	// If not EOM
    {
      uint j=0;
      for (uint i=1 ; i < arg_count ; i++)
      {
	array->set(j,args[i]);
	if (!args[i]->null_value)			// Skip NULL values
	  j++;
	else
	  have_null= 1;
      }
      if ((array->used_count=j))
	array->sort();
    }
  }
  else
  {
    in_item= cmp_item::get_comparator(args[0]);
    if (cmp_type  == STRING_RESULT)
      in_item->cmp_charset= cmp_collation.collation;
  }
  maybe_null= args[0]->maybe_null;
  max_length= 1;
}


void Item_func_in::print(String *str)
{
  str->append('(');
  args[0]->print(str);
  str->append(" in (", 5);
  print_args(str, 1);
  str->append("))", 2);
}


longlong Item_func_in::val_int()
{
  if (array)
  {
    int tmp=array->find(args[0]);
    null_value=args[0]->null_value || (!tmp && have_null);
    return tmp;
  }
  in_item->store_value(args[0]);
  if ((null_value=args[0]->null_value))
    return 0;
  have_null= 0;
  for (uint i=1 ; i < arg_count ; i++)
  {
    if (!in_item->cmp(args[i]) && !args[i]->null_value)
      return 1;					// Would maybe be nice with i ?
    have_null|= args[i]->null_value;
  }
  null_value= have_null;
  return 0;
}


longlong Item_func_bit_or::val_int()
{
  ulonglong arg1= (ulonglong) args[0]->val_int();
  if (args[0]->null_value)
  {
    null_value=1; /* purecov: inspected */
    return 0; /* purecov: inspected */
  }
  ulonglong arg2= (ulonglong) args[1]->val_int();
  if (args[1]->null_value)
  {
    null_value=1;
    return 0;
  }
  null_value=0;
  return (longlong) (arg1 | arg2);
}


longlong Item_func_bit_and::val_int()
{
  ulonglong arg1= (ulonglong) args[0]->val_int();
  if (args[0]->null_value)
  {
    null_value=1; /* purecov: inspected */
    return 0; /* purecov: inspected */
  }
  ulonglong arg2= (ulonglong) args[1]->val_int();
  if (args[1]->null_value)
  {
    null_value=1; /* purecov: inspected */
    return 0; /* purecov: inspected */
  }
  null_value=0;
  return (longlong) (arg1 & arg2);
}

Item_cond::Item_cond(THD *thd, Item_cond &item)
  :Item_bool_func(thd, item),
   abort_on_null(item.abort_on_null),
   and_tables_cache(item.and_tables_cache)
{
  /*
    here should be following text:

  List_iterator_fast<Item*> li(item.list);
  while(Item *it= li++)
    list.push_back(it);

    but it do not need,
    because this constructor used only for AND/OR and
    argument list will be copied by copy_andor_arguments call
  */

}

void Item_cond::copy_andor_arguments(THD *thd, Item_cond *item)
{
  List_iterator_fast<Item> li(item->list);
  while(Item *it= li++)
    list.push_back(it->copy_andor_structure(thd));
}

bool
Item_cond::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
{
  List_iterator<Item> li(list);
  Item *item;
#ifndef EMBEDDED_LIBRARY
  char buff[sizeof(char*)];			// Max local vars in function
#endif
  not_null_tables_cache= used_tables_cache= 0;
  const_item_cache= 0;
  /*
    and_table_cache is the value that Item_cond_or() returns for
    not_null_tables()
  */
  and_tables_cache= ~(table_map) 0;

  if (check_stack_overrun(thd, buff))
    return 1;					// Fatal error flag is set!
  while ((item=li++))
  {
    table_map tmp_table_map;
    while (item->type() == Item::COND_ITEM &&
	   ((Item_cond*) item)->functype() == functype())
    {						// Identical function
      li.replace(((Item_cond*) item)->list);
      ((Item_cond*) item)->list.empty();
#ifdef DELETE_ITEMS
      delete (Item_cond*) item;
#endif
      item= *li.ref();				// new current item
    }
    if (abort_on_null)
      item->top_level_item();
    if ((!item->fixed &&
	 item->fix_fields(thd, tables, li.ref())) || item->check_cols(1))
      return 1; /* purecov: inspected */
    used_tables_cache|=     item->used_tables();
    tmp_table_map=	    item->not_null_tables();
    not_null_tables_cache|= tmp_table_map;
    and_tables_cache&=      tmp_table_map;
    const_item_cache&=	    item->const_item();
    with_sum_func=	    with_sum_func || item->with_sum_func;
    if (item->maybe_null)
      maybe_null=1;
  }
  thd->lex.current_select->cond_count+=list.elements;
  fix_length_and_dec();
  fixed= 1;
  return 0;
}

bool Item_cond::walk(Item_processor processor, byte *arg)
{
  List_iterator_fast<Item> li(list);
  Item *item;
  while ((item= li++))
    if (item->walk(processor, arg))
      return 1;
  return Item_func::walk(processor, arg);
}

void Item_cond::split_sum_func(Item **ref_pointer_array, List<Item> &fields)
{
  List_iterator<Item> li(list);
  Item *item;
  used_tables_cache=0;
  const_item_cache=0;
  while ((item=li++))
  {
    if (item->with_sum_func && item->type() != SUM_FUNC_ITEM)
      item->split_sum_func(ref_pointer_array, fields);
    else if (item->used_tables() || item->type() == SUM_FUNC_ITEM)
    {
      uint el= fields.elements;
      fields.push_front(item);
      ref_pointer_array[el]= item;
      li.replace(new Item_ref(ref_pointer_array + el, 0, item->name));
    }
    item->update_used_tables();
    used_tables_cache|=item->used_tables();
    const_item_cache&=item->const_item();
  }
}


table_map
Item_cond::used_tables() const
{						// This caches used_tables
  return used_tables_cache;
}


void Item_cond::update_used_tables()
{
  List_iterator_fast<Item> li(list);
  Item *item;

  used_tables_cache=0;
  const_item_cache=1;
  while ((item=li++))
  {
    item->update_used_tables();
    used_tables_cache|= item->used_tables();
    const_item_cache&=  item->const_item();
  }
}


void Item_cond::print(String *str)
{
  str->append('(');
  List_iterator_fast<Item> li(list);
  Item *item;
  if ((item=li++))
    item->print(str);
  while ((item=li++))
  {
    str->append(' ');
    str->append(func_name());
    str->append(' ');
    item->print(str);
  }
  str->append(')');
}


void Item_cond::neg_arguments()
{
  List_iterator<Item> li(list);
  Item *item;
  while ((item= li++))		/* Apply not transformation to the arguments */
  {
    Item *new_item= item->neg_transformer();
    VOID(li.replace(new_item ? new_item : new Item_func_not(item)));
  }
}


/*
  Evalution of AND(expr, expr, expr ...)

  NOTES:
    abort_if_null is set for AND expressions for which we don't care if the
    result is NULL or 0. This is set for:
    - WHERE clause
    - HAVING clause
    - IF(expression)

  RETURN VALUES
    1  If all expressions are true
    0  If all expressions are false or if we find a NULL expression and
       'abort_on_null' is set.
    NULL if all expression are either 1 or NULL
*/


longlong Item_cond_and::val_int()
{
  List_iterator_fast<Item> li(list);
  Item *item;
  null_value= 0;
  while ((item=li++))
  {
    if (item->val_int() == 0)
    {
      if (abort_on_null || !(null_value= item->null_value))
	return 0;				// return FALSE
    }
  }
  return null_value ? 0 : 1;
}


longlong Item_cond_or::val_int()
{
  List_iterator_fast<Item> li(list);
  Item *item;
  null_value=0;
  while ((item=li++))
  {
    if (item->val_int() != 0)
    {
      null_value=0;
      return 1;
    }
    if (item->null_value)
      null_value=1;
  }
  return 0;
}

/*
  Create an AND expression from two expressions

  SYNOPSIS
   and_expressions()
   a		expression or NULL
   b    	expression.
   org_item	Don't modify a if a == *org_item
		If a == NULL, org_item is set to point at b,
		to ensure that future calls will not modify b.

  NOTES
    This will not modify item pointed to by org_item or b
    The idea is that one can call this in a loop and create and
    'and' over all items without modifying any of the original items.

  RETURN
    NULL	Error
    Item
*/

Item *and_expressions(Item *a, Item *b, Item **org_item)
{
  if (!a)
    return (*org_item= (Item*) b);
  if (a == *org_item)
  {
    Item_cond *res;
    if ((res= new Item_cond_and(a, (Item*) b)))
    {
      res->used_tables_cache= a->used_tables() | b->used_tables();
      res->not_null_tables_cache= a->not_null_tables() | b->not_null_tables();
    }
    return res;
  }
  if (((Item_cond_and*) a)->add((Item*) b))
    return 0;
  ((Item_cond_and*) a)->used_tables_cache|= b->used_tables();
  ((Item_cond_and*) a)->not_null_tables_cache|= b->not_null_tables();
  return a;
}


longlong Item_func_isnull::val_int()
{
  /*
    Handle optimization if the argument can't be null
    This has to be here because of the test in update_used_tables().
  */
  if (!used_tables_cache)
    return cached_value;
  return args[0]->is_null() ? 1: 0;
}

longlong Item_is_not_null_test::val_int()
{
  DBUG_ENTER("Item_is_not_null_test::val_int");
  if (!used_tables_cache)
  {
    owner->was_null|= (!cached_value);
    DBUG_PRINT("info", ("cached :%d", cached_value));
    DBUG_RETURN(cached_value);
  }
  if (args[0]->is_null())
  {
    DBUG_PRINT("info", ("null"))
    owner->was_null|= 1;
    DBUG_RETURN(0);
  }
  else
    DBUG_RETURN(1);
}

/* Optimize case of not_null_column IS NULL */
void Item_is_not_null_test::update_used_tables()
{
  if (!args[0]->maybe_null)
  {
    used_tables_cache= 0;			/* is always true */
    cached_value= (longlong) 1;
  }
  else
  {
    args[0]->update_used_tables();
    if (!(used_tables_cache=args[0]->used_tables()))
    {
      /* Remember if the value is always NULL or never NULL */
      cached_value= (longlong) !args[0]->is_null();
    }
  }
}


longlong Item_func_isnotnull::val_int()
{
  return args[0]->is_null() ? 0 : 1;
}


void Item_func_isnotnull::print(String *str)
{
  str->append('(');
  args[0]->print(str);
  str->append(" is not null)", 13);
}


longlong Item_func_like::val_int()
{
  String* res = args[0]->val_str(&tmp_value1);
  if (args[0]->null_value)
  {
    null_value=1;
    return 0;
  }
  String* res2 = args[1]->val_str(&tmp_value2);
  if (args[1]->null_value)
  {
    null_value=1;
    return 0;
  }
  null_value=0;
  if (canDoTurboBM)
    return turboBM_matches(res->ptr(), res->length()) ? 1 : 0;
  return my_wildcmp(cmp.cmp_collation.collation,
		    res->ptr(),res->ptr()+res->length(),
		    res2->ptr(),res2->ptr()+res2->length(),
		    escape,wild_one,wild_many) ? 0 : 1;
}


/* We can optimize a where if first character isn't a wildcard */

Item_func::optimize_type Item_func_like::select_optimize() const
{
  if (args[1]->const_item())
  {
    String* res2= args[1]->val_str((String *)&tmp_value2);

    if (!res2)
      return OPTIMIZE_NONE;

    if (*res2->ptr() != wild_many)
    {
      if (args[0]->result_type() != STRING_RESULT || *res2->ptr() != wild_one)
	return OPTIMIZE_OP;
    }
  }
  return OPTIMIZE_NONE;
}


bool Item_func_like::fix_fields(THD *thd, TABLE_LIST *tlist, Item ** ref)
{
  if (Item_bool_func2::fix_fields(thd, tlist, ref))
    return 1;

  /*
    We could also do boyer-more for non-const items, but as we would have to
    recompute the tables for each row it's not worth it.
  */
  if (args[1]->const_item() && !use_strnxfrm(collation.collation) &&
      !(specialflag & SPECIAL_NO_NEW_FUNC))
  {
    String* res2 = args[1]->val_str(&tmp_value2);
    if (!res2)
      return 0;					// Null argument

    const size_t len   = res2->length();
    const char*  first = res2->ptr();
    const char*  last  = first + len - 1;
    /*
      len must be > 2 ('%pattern%')
      heuristic: only do TurboBM for pattern_len > 2
    */

    if (len > MIN_TURBOBM_PATTERN_LEN + 2 &&
	*first == wild_many &&
	*last  == wild_many)
    {
      const char* tmp = first + 1;
      for (; *tmp != wild_many && *tmp != wild_one && *tmp != escape; tmp++) ;
      canDoTurboBM = (tmp == last) && !use_mb(args[0]->collation.collation);
    }

    if (canDoTurboBM)
    {
      pattern     = first + 1;
      pattern_len = len - 2;
      DBUG_PRINT("info", ("Initializing pattern: '%s'", first));
      int *suff = (int*) thd->alloc(sizeof(int)*((pattern_len + 1)*2+
						 alphabet_size));
      bmGs      = suff + pattern_len + 1;
      bmBc      = bmGs + pattern_len + 1;
      turboBM_compute_good_suffix_shifts(suff);
      turboBM_compute_bad_character_shifts();
      DBUG_PRINT("info",("done"));
    }
  }
  return 0;
}

#ifdef USE_REGEX

bool
Item_func_regex::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
{
  if (args[0]->fix_fields(thd, tables, args) || args[0]->check_cols(1) ||
      args[1]->fix_fields(thd,tables, args + 1) || args[1]->check_cols(1))
    return 1;					/* purecov: inspected */
  with_sum_func=args[0]->with_sum_func || args[1]->with_sum_func;
  max_length= 1;
  decimals= 0;

  if (agg_arg_collations(cmp_collation, args, 2))
    return 1;

  used_tables_cache=args[0]->used_tables() | args[1]->used_tables();
  not_null_tables_cache= (args[0]->not_null_tables() |
			  args[1]->not_null_tables());
  const_item_cache=args[0]->const_item() && args[1]->const_item();
  if (!regex_compiled && args[1]->const_item())
  {
    char buff[MAX_FIELD_WIDTH];
    String tmp(buff,sizeof(buff),&my_charset_bin);
    String *res=args[1]->val_str(&tmp);
    if (args[1]->null_value)
    {						// Will always return NULL
      maybe_null=1;
      return 0;
    }
    int error;
    if ((error=regcomp(&preg,res->c_ptr(),
		       (cmp_collation.collation->state & MY_CS_BINSORT) ?
		       REG_EXTENDED | REG_NOSUB :
		       REG_EXTENDED | REG_NOSUB | REG_ICASE,
		       cmp_collation.collation)))
    {
      (void) regerror(error,&preg,buff,sizeof(buff));
      my_printf_error(ER_REGEXP_ERROR,ER(ER_REGEXP_ERROR),MYF(0),buff);
      return 1;
    }
    regex_compiled=regex_is_const=1;
    maybe_null=args[0]->maybe_null;
  }
  else
    maybe_null=1;
  fixed= 1;
  return 0;
}


longlong Item_func_regex::val_int()
{
  char buff[MAX_FIELD_WIDTH];
  String *res, tmp(buff,sizeof(buff),&my_charset_bin);

  res=args[0]->val_str(&tmp);
  if (args[0]->null_value)
  {
    null_value=1;
    return 0;
  }
  if (!regex_is_const)
  {
    char buff2[MAX_FIELD_WIDTH];
    String *res2, tmp2(buff2,sizeof(buff2),&my_charset_bin);

    res2= args[1]->val_str(&tmp2);
    if (args[1]->null_value)
    {
      null_value=1;
      return 0;
    }
    if (!regex_compiled || sortcmp(res2,&prev_regexp,&my_charset_bin))
    {
      prev_regexp.copy(*res2);
      if (regex_compiled)
      {
	regfree(&preg);
	regex_compiled=0;
      }
      if (regcomp(&preg,res2->c_ptr(),
		  (cmp_collation.collation->state & MY_CS_BINSORT) ?
		  REG_EXTENDED | REG_NOSUB :
		  REG_EXTENDED | REG_NOSUB | REG_ICASE,
		  cmp_collation.collation))
      {
	null_value=1;
	return 0;
      }
      regex_compiled=1;
    }
  }
  null_value=0;
  return regexec(&preg,res->c_ptr(),0,(regmatch_t*) 0,0) ? 0 : 1;
}


Item_func_regex::~Item_func_regex()
{
  if (regex_compiled)
  {
    regfree(&preg);
    regex_compiled=0;
  }
}

#endif /* USE_REGEX */


#ifdef LIKE_CMP_TOUPPER
#define likeconv(cs,A) (uchar) (cs)->toupper(A)
#else
#define likeconv(cs,A) (uchar) (cs)->sort_order[(uchar) (A)]
#endif


/**********************************************************************
  turboBM_compute_suffixes()
  Precomputation dependent only on pattern_len.
**********************************************************************/

void Item_func_like::turboBM_compute_suffixes(int *suff)
{
  const int   plm1 = pattern_len - 1;
  int            f = 0;
  int            g = plm1;
  int *const splm1 = suff + plm1;
  CHARSET_INFO	*cs=system_charset_info;	// QQ Needs to be fixed

  *splm1 = pattern_len;

  if (cmp.cmp_collation.collation == &my_charset_bin)
  {
    int i;
    for (i = pattern_len - 2; i >= 0; i--)
    {
      int tmp = *(splm1 + i - f);
      if (g < i && tmp < i - g)
	suff[i] = tmp;
      else
      {
	if (i < g)
	  g = i; // g = min(i, g)
	f = i;
	while (g >= 0 && pattern[g] == pattern[g + plm1 - f])
	  g--;
	suff[i] = f - g;
      }
    }
  }
  else
  {
    int i;
    for (i = pattern_len - 2; 0 <= i; --i)
    {
      int tmp = *(splm1 + i - f);
      if (g < i && tmp < i - g)
	suff[i] = tmp;
      else
      {
	if (i < g)
	  g = i; // g = min(i, g)
	f = i;
	while (g >= 0 &&
	       likeconv(cs, pattern[g]) == likeconv(cs, pattern[g + plm1 - f]))
	  g--;
	suff[i] = f - g;
      }
    }
  }
}


/**********************************************************************
   turboBM_compute_good_suffix_shifts()
   Precomputation dependent only on pattern_len.
**********************************************************************/

void Item_func_like::turboBM_compute_good_suffix_shifts(int *suff)
{
  turboBM_compute_suffixes(suff);

  int *end = bmGs + pattern_len;
  int *k;
  for (k = bmGs; k < end; k++)
    *k = pattern_len;

  int tmp;
  int i;
  int j          = 0;
  const int plm1 = pattern_len - 1;
  for (i = plm1; i > -1; i--)
  {
    if (suff[i] == i + 1)
    {
      for (tmp = plm1 - i; j < tmp; j++)
      {
	int *tmp2 = bmGs + j;
	if (*tmp2 == pattern_len)
	  *tmp2 = tmp;
      }
    }
  }

  int *tmp2;
  for (tmp = plm1 - i; j < tmp; j++)
  {
    tmp2 = bmGs + j;
    if (*tmp2 == pattern_len)
      *tmp2 = tmp;
  }

  tmp2 = bmGs + plm1;
  for (i = 0; i <= pattern_len - 2; i++)
    *(tmp2 - suff[i]) = plm1 - i;
}


/**********************************************************************
   turboBM_compute_bad_character_shifts()
   Precomputation dependent on pattern_len.
**********************************************************************/

void Item_func_like::turboBM_compute_bad_character_shifts()
{
  int *i;
  int *end = bmBc + alphabet_size;
  int j;
  const int plm1 = pattern_len - 1;
  CHARSET_INFO	*cs=system_charset_info;	// QQ Needs to be fixed

  for (i = bmBc; i < end; i++)
    *i = pattern_len;

  if (cmp.cmp_collation.collation == &my_charset_bin)
  {
    for (j = 0; j < plm1; j++)
      bmBc[(uint) (uchar) pattern[j]] = plm1 - j;
  }
  else
  {
    for (j = 0; j < plm1; j++)
      bmBc[(uint) likeconv(cs,pattern[j])] = plm1 - j;
  }
}


/**********************************************************************
  turboBM_matches()
  Search for pattern in text, returns true/false for match/no match
**********************************************************************/

bool Item_func_like::turboBM_matches(const char* text, int text_len) const
{
  register int bcShift;
  register int turboShift;
  int shift = pattern_len;
  int j     = 0;
  int u     = 0;
  CHARSET_INFO	*cs= cmp.cmp_collation.collation;	// QQ Needs to be fixed

  const int plm1=  pattern_len - 1;
  const int tlmpl= text_len - pattern_len;

  /* Searching */
  if (cmp.cmp_collation.collation == &my_charset_bin)
  {
    while (j <= tlmpl)
    {
      register int i= plm1;
      while (i >= 0 && pattern[i] == text[i + j])
      {
	i--;
	if (i == plm1 - shift)
	  i-= u;
      }
      if (i < 0)
	return 1;

      register const int v = plm1 - i;
      turboShift = u - v;
      bcShift    = bmBc[(uint) (uchar) text[i + j]] - plm1 + i;
      shift      = max(turboShift, bcShift);
      shift      = max(shift, bmGs[i]);
      if (shift == bmGs[i])
	u = min(pattern_len - shift, v);
      else
      {
	if (turboShift < bcShift)
	  shift = max(shift, u + 1);
	u = 0;
      }
      j+= shift;
    }
    return 0;
  }
  else
  {
    while (j <= tlmpl)
    {
      register int i = plm1;
      while (i >= 0 && likeconv(cs,pattern[i]) == likeconv(cs,text[i + j]))
      {
	i--;
	if (i == plm1 - shift)
	  i-= u;
      }
      if (i < 0)
	return 1;

      register const int v = plm1 - i;
      turboShift = u - v;
      bcShift    = bmBc[(uint) likeconv(cs, text[i + j])] - plm1 + i;
      shift      = max(turboShift, bcShift);
      shift      = max(shift, bmGs[i]);
      if (shift == bmGs[i])
	u = min(pattern_len - shift, v);
      else
      {
	if (turboShift < bcShift)
	  shift = max(shift, u + 1);
	u = 0;
      }
      j+= shift;
    }
    return 0;
  }
}


/*
  Make a logical XOR of the arguments.

  SYNOPSIS
    val_int()

  DESCRIPTION
  If either operator is NULL, return NULL.

  NOTE
    As we don't do any index optimization on XOR this is not going to be
    very fast to use.

  TODO (low priority)
    Change this to be optimized as:
      A XOR B   ->  (A) == 1 AND (B) <> 1) OR (A <> 1 AND (B) == 1)
    To be able to do this, we would however first have to extend the MySQL
    range optimizer to handle OR better.
*/

longlong Item_cond_xor::val_int()
{
  List_iterator<Item> li(list);
  Item *item;
  int result=0;	
  null_value=0;
  while ((item=li++))
  {
    result^= (item->val_int() != 0);
    if (item->null_value)
    {
      null_value=1;
      return 0;
    }
  }
  return (longlong) result;
}

/*
  Apply NOT transformation to the item and return a new one.

  SYNPOSIS
    neg_transformer()

  DESCRIPTION
    Transform the item using next rules:
       a AND b AND ...    -> NOT(a) OR NOT(b) OR ...
       a OR b OR ...      -> NOT(a) AND NOT(b) AND ...
       NOT(a)             -> a
       a = b              -> a != b
       a != b             -> a = b
       a < b              -> a >= b
       a >= b             -> a < b
       a > b              -> a <= b
       a <= b             -> a > b
       IS NULL(a)         -> IS NOT NULL(a)
       IS NOT NULL(a)     -> IS NULL(a)

  NOTE
    This method is used in the eliminate_not_funcs() function.

  RETURN
    New item or
    NULL if we cannot apply NOT transformation (see Item::neg_transformer()).
*/

Item *Item_func_not::neg_transformer()		/* NOT(x)  ->  x */
{
  /* We should apply negation elimination to the argument of the NOT function */
  return eliminate_not_funcs(args[0]);
}

Item *Item_func_eq::neg_transformer()		/* a = b  ->  a != b */
{
  return new Item_func_ne(args[0], args[1]);	
}

Item *Item_func_ne::neg_transformer()		/* a != b  ->  a = b */
{
  return new Item_func_eq(args[0], args[1]);
}

Item *Item_func_lt::neg_transformer()		/* a < b  ->  a >= b */
{
  return new Item_func_ge(args[0], args[1]);
}

Item *Item_func_ge::neg_transformer()		/* a >= b  ->  a < b */
{
  return new Item_func_lt(args[0], args[1]);
}

Item *Item_func_gt::neg_transformer()		/* a > b  ->  a <= b */
{
  return new Item_func_le(args[0], args[1]);
}

Item *Item_func_le::neg_transformer()		/* a <= b  ->  a > b */
{
  return new Item_func_gt(args[0], args[1]);
}

Item *Item_func_isnull::neg_transformer()	/* a IS NULL  ->  a IS NOT NULL */
{
  return new Item_func_isnotnull(args[0]);
}

Item *Item_func_isnotnull::neg_transformer()	/* a IS NOT NULL  ->  a IS NULL */
{
  return new Item_func_isnull(args[0]);
}

Item *Item_cond_and::neg_transformer()		/* NOT(a AND b AND ...)  -> */
					/* NOT a OR NOT b OR ... */
{
  neg_arguments();
  return new Item_cond_or(list);
}

Item *Item_cond_or::neg_transformer()		/* NOT(a OR b OR ...)  -> */
					/* NOT a AND NOT b AND ... */
{
  neg_arguments();
  return new Item_cond_and(list);
}
