path: root/sql/item_func.h

/* Copyright (c) 2000, 2013, 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 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
*/


/* Function items used by mysql */

#ifdef USE_PRAGMA_INTERFACE
#pragma interface			/* gcc class implementation */
#endif

#ifdef HAVE_IEEEFP_H
extern "C"				/* Bug in BSDI include file */
{
#include <ieeefp.h>
}
#endif

class Item_func :public Item_result_field
{
protected:
  Item **args, *tmp_arg[2];
  /*
    Allowed numbers of columns in result (usually 1, which means scalar value)
    0 means get this number from first argument
  */
  uint allowed_arg_cols;
public:
  uint arg_count;
  table_map used_tables_cache, not_null_tables_cache;
  bool const_item_cache;
  enum Functype { UNKNOWN_FUNC,EQ_FUNC,EQUAL_FUNC,NE_FUNC,LT_FUNC,LE_FUNC,
		  GE_FUNC,GT_FUNC,FT_FUNC,
		  LIKE_FUNC,ISNULL_FUNC,ISNOTNULL_FUNC,
		  COND_AND_FUNC, COND_OR_FUNC, COND_XOR_FUNC,
                  BETWEEN, IN_FUNC, MULT_EQUAL_FUNC,
		  INTERVAL_FUNC, ISNOTNULLTEST_FUNC,
		  SP_EQUALS_FUNC, SP_DISJOINT_FUNC,SP_INTERSECTS_FUNC,
		  SP_TOUCHES_FUNC,SP_CROSSES_FUNC,SP_WITHIN_FUNC,
		  SP_CONTAINS_FUNC,SP_OVERLAPS_FUNC,
		  SP_STARTPOINT,SP_ENDPOINT,SP_EXTERIORRING,
		  SP_POINTN,SP_GEOMETRYN,SP_INTERIORRINGN,
                  NOT_FUNC, NOT_ALL_FUNC,
                  NOW_FUNC, TRIG_COND_FUNC,
                  SUSERVAR_FUNC, GUSERVAR_FUNC, COLLATE_FUNC,
                  EXTRACT_FUNC, CHAR_TYPECAST_FUNC, FUNC_SP, UDF_FUNC,
                  NEG_FUNC, GSYSVAR_FUNC };
  enum optimize_type { OPTIMIZE_NONE,OPTIMIZE_KEY,OPTIMIZE_OP, OPTIMIZE_NULL,
                       OPTIMIZE_EQUAL };
  enum Type type() const { return FUNC_ITEM; }
  virtual enum Functype functype() const   { return UNKNOWN_FUNC; }
  Item_func(void):
    allowed_arg_cols(1), arg_count(0)
  {
    with_sum_func= 0;
  }
  Item_func(Item *a):
    allowed_arg_cols(1), arg_count(1)
  {
    args= tmp_arg;
    args[0]= a;
    with_sum_func= a->with_sum_func;
  }
  Item_func(Item *a,Item *b):
    allowed_arg_cols(1), arg_count(2)
  {
    args= tmp_arg;
    args[0]= a; args[1]= b;
    with_sum_func= a->with_sum_func || b->with_sum_func;
  }
  Item_func(Item *a,Item *b,Item *c):
    allowed_arg_cols(1)
  {
    arg_count= 0;
    if ((args= (Item**) sql_alloc(sizeof(Item*)*3)))
    {
      arg_count= 3;
      args[0]= a; args[1]= b; args[2]= c;
      with_sum_func= a->with_sum_func || b->with_sum_func || c->with_sum_func;
    }
  }
  Item_func(Item *a,Item *b,Item *c,Item *d):
    allowed_arg_cols(1)
  {
    arg_count= 0;
    if ((args= (Item**) sql_alloc(sizeof(Item*)*4)))
    {
      arg_count= 4;
      args[0]= a; args[1]= b; args[2]= c; args[3]= d;
      with_sum_func= a->with_sum_func || b->with_sum_func ||
	c->with_sum_func || d->with_sum_func;
    }
  }
  Item_func(Item *a,Item *b,Item *c,Item *d,Item* e):
    allowed_arg_cols(1)
  {
    arg_count= 5;
    if ((args= (Item**) sql_alloc(sizeof(Item*)*5)))
    {
      args[0]= a; args[1]= b; args[2]= c; args[3]= d; args[4]= e;
      with_sum_func= a->with_sum_func || b->with_sum_func ||
	c->with_sum_func || d->with_sum_func || e->with_sum_func ;
    }
  }
  Item_func(List<Item> &list);
  // Constructor used for Item_cond_and/or (see Item comment)
  Item_func(THD *thd, Item_func *item);
  bool fix_fields(THD *, Item **ref);
  table_map used_tables() const;
  table_map not_null_tables() const;
  void update_used_tables();
  bool eq(const Item *item, bool binary_cmp) const;
  virtual optimize_type select_optimize() const { return OPTIMIZE_NONE; }
  virtual bool have_rev_func() const { return 0; }
  virtual Item *key_item() const { return args[0]; }
  virtual bool const_item() const { return const_item_cache; }
  inline Item **arguments() const { return args; }
  void set_arguments(List<Item> &list);
  inline uint argument_count() const { return arg_count; }
  inline void remove_arguments() { arg_count=0; }
  void split_sum_func(THD *thd, Item **ref_pointer_array, List<Item> &fields);
  virtual void print(String *str, enum_query_type query_type);
  void print_op(String *str, enum_query_type query_type);
  void print_args(String *str, uint from, enum_query_type query_type);
  virtual void fix_num_length_and_dec();
  void count_only_length();
  void count_real_length();
  void count_decimal_length();
  inline bool get_arg0_date(MYSQL_TIME *ltime, uint fuzzy_date)
  {
    return (null_value=args[0]->get_date(ltime, fuzzy_date));
  }
  inline bool get_arg0_time(MYSQL_TIME *ltime)
  {
    return (null_value=args[0]->get_time(ltime));
  }
  bool is_null() { 
    update_null_value();
    return null_value; 
  }
  void signal_divide_by_null();
  friend class udf_handler;
  Field *tmp_table_field() { return result_field; }
  Field *tmp_table_field(TABLE *t_arg);
  Item *get_tmp_table_item(THD *thd);

  my_decimal *val_decimal(my_decimal *);

  bool agg_arg_collations(DTCollation &c, Item **items, uint nitems,
                          uint flags)
  {
    return agg_item_collations(c, func_name(), items, nitems, flags, 1);
  }
  bool agg_arg_collations_for_comparison(DTCollation &c,
                                         Item **items, uint nitems,
                                         uint flags)
  {
    return agg_item_collations_for_comparison(c, func_name(),
                                              items, nitems, flags);
  }
  bool agg_arg_charsets(DTCollation &c, Item **items, uint nitems,
                        uint flags, int item_sep)
  {
    return agg_item_charsets(c, func_name(), items, nitems, flags, item_sep);
  }
  bool walk(Item_processor processor, bool walk_subquery, uchar *arg);
  Item *transform(Item_transformer transformer, uchar *arg);
  Item* compile(Item_analyzer analyzer, uchar **arg_p,
                Item_transformer transformer, uchar *arg_t);
  void traverse_cond(Cond_traverser traverser,
                     void * arg, traverse_order order);
  bool is_expensive_processor(uchar *arg);
  virtual bool is_expensive() { return 0; }
  inline double fix_result(double value)
  {
    if (isfinite(value))
      return value;
    null_value=1;
    return 0.0;
  }

  bool has_timestamp_args()
  {
    DBUG_ASSERT(fixed == TRUE);
    for (uint i= 0; i < arg_count; i++)
    {
      if (args[i]->type() == Item::FIELD_ITEM &&
          args[i]->field_type() == MYSQL_TYPE_TIMESTAMP)
        return TRUE;
    }
    return FALSE;
  }

  bool has_date_args()
  {
    DBUG_ASSERT(fixed == TRUE);
    for (uint i= 0; i < arg_count; i++)
    {
      if (args[i]->type() == Item::FIELD_ITEM &&
          (args[i]->field_type() == MYSQL_TYPE_DATE ||
           args[i]->field_type() == MYSQL_TYPE_DATETIME))
        return TRUE;
    }
    return FALSE;
  }

  bool has_time_args()
  {
    DBUG_ASSERT(fixed == TRUE);
    for (uint i= 0; i < arg_count; i++)
    {
      if (args[i]->type() == Item::FIELD_ITEM &&
          (args[i]->field_type() == MYSQL_TYPE_TIME ||
           args[i]->field_type() == MYSQL_TYPE_DATETIME))
        return TRUE;
    }
    return FALSE;
  }

  bool has_datetime_args()
  {
    DBUG_ASSERT(fixed == TRUE);
    for (uint i= 0; i < arg_count; i++)
    {
      if (args[i]->type() == Item::FIELD_ITEM &&
          args[i]->field_type() == MYSQL_TYPE_DATETIME)
        return TRUE;
    }
    return FALSE;
  }

  /*
    We assume the result of any function that has a TIMESTAMP argument to be
    timezone-dependent, since a TIMESTAMP value in both numeric and string
    contexts is interpreted according to the current timezone.
    The only exception is UNIX_TIMESTAMP() which returns the internal
    representation of a TIMESTAMP argument verbatim, and thus does not depend on
    the timezone.
   */
  virtual bool check_valid_arguments_processor(uchar *bool_arg)
  {
    return has_timestamp_args();
  }

  virtual bool find_function_processor (uchar *arg)
  {
    return functype() == *(Functype *) arg;
  }
};


class Item_real_func :public Item_func
{
public:
  Item_real_func() :Item_func() {}
  Item_real_func(Item *a) :Item_func(a) {}
  Item_real_func(Item *a,Item *b) :Item_func(a,b) {}
  Item_real_func(List<Item> &list) :Item_func(list) {}
  String *val_str(String*str);
  my_decimal *val_decimal(my_decimal *decimal_value);
  longlong val_int()
    { DBUG_ASSERT(fixed == 1); return (longlong) rint(val_real()); }
  enum Item_result result_type () const { return REAL_RESULT; }
  void fix_length_and_dec()
  { decimals= NOT_FIXED_DEC; max_length= float_length(decimals); }
};


class Item_func_numhybrid: public Item_func
{
protected:
  Item_result hybrid_type;
public:
  Item_func_numhybrid(Item *a) :Item_func(a), hybrid_type(REAL_RESULT)
  {}
  Item_func_numhybrid(Item *a,Item *b)
    :Item_func(a,b), hybrid_type(REAL_RESULT)
  {}
  Item_func_numhybrid(List<Item> &list)
    :Item_func(list), hybrid_type(REAL_RESULT)
  {}

  enum Item_result result_type () const { return hybrid_type; }
  void fix_length_and_dec();
  void fix_num_length_and_dec();
  virtual void find_num_type()= 0; /* To be called from fix_length_and_dec */

  double val_real();
  longlong val_int();
  my_decimal *val_decimal(my_decimal *);
  String *val_str(String*str);

  /**
     @brief Performs the operation that this functions implements when the
     result type is INT.

     @return The result of the operation.
  */
  virtual longlong int_op()= 0;

  /**
     @brief Performs the operation that this functions implements when the
     result type is REAL.

     @return The result of the operation.
  */
  virtual double real_op()= 0;

  /**
     @brief Performs the operation that this functions implements when the
     result type is DECIMAL.

     @param A pointer where the DECIMAL value will be allocated.
     @return 
       - 0 If the result is NULL
       - The same pointer it was given, with the area initialized to the
         result of the operation.
  */
  virtual my_decimal *decimal_op(my_decimal *)= 0;

  /**
     @brief Performs the operation that this functions implements when the
     result type is a string type.

     @return The result of the operation.
  */
  virtual String *str_op(String *)= 0;
  bool is_null() { update_null_value(); return null_value; }
};

/* function where type of result detected by first argument */
class Item_func_num1: public Item_func_numhybrid
{
public:
  Item_func_num1(Item *a) :Item_func_numhybrid(a) {}
  Item_func_num1(Item *a, Item *b) :Item_func_numhybrid(a, b) {}

  void fix_num_length_and_dec();
  void find_num_type();
  String *str_op(String *str) { DBUG_ASSERT(0); return 0; }
};


/* Base class for operations like '+', '-', '*' */
class Item_num_op :public Item_func_numhybrid
{
 public:
  Item_num_op(Item *a,Item *b) :Item_func_numhybrid(a, b) {}
  virtual void result_precision()= 0;

  virtual inline void print(String *str, enum_query_type query_type)
  {
    print_op(str, query_type);
  }

  void find_num_type();
  String *str_op(String *str) { DBUG_ASSERT(0); return 0; }
};


class Item_int_func :public Item_func
{
public:
  Item_int_func() :Item_func() { max_length= 21; }
  Item_int_func(Item *a) :Item_func(a) { max_length= 21; }
  Item_int_func(Item *a,Item *b) :Item_func(a,b) { max_length= 21; }
  Item_int_func(Item *a,Item *b,Item *c) :Item_func(a,b,c)
  { max_length= 21; }
  Item_int_func(List<Item> &list) :Item_func(list) { max_length= 21; }
  Item_int_func(THD *thd, Item_int_func *item) :Item_func(thd, item) {}
  double val_real();
  String *val_str(String*str);
  enum Item_result result_type () const { return INT_RESULT; }
  void fix_length_and_dec() {}
};


class Item_func_connection_id :public Item_int_func
{
  longlong value;

public:
  Item_func_connection_id() {}
  const char *func_name() const { return "connection_id"; }
  void fix_length_and_dec();
  bool fix_fields(THD *thd, Item **ref);
  longlong val_int() { DBUG_ASSERT(fixed == 1); return value; }
};


class Item_func_signed :public Item_int_func
{
public:
  Item_func_signed(Item *a) :Item_int_func(a)
  {
    unsigned_flag= 0;
  }
  const char *func_name() const { return "cast_as_signed"; }
  longlong val_int();
  longlong val_int_from_str(int *error);
  void fix_length_and_dec()
  {
    max_length= min(args[0]->max_length,MY_INT64_NUM_DECIMAL_DIGITS);
  }
  virtual void print(String *str, enum_query_type query_type);
  uint decimal_precision() const { return args[0]->decimal_precision(); }
};


class Item_func_unsigned :public Item_func_signed
{
public:
  Item_func_unsigned(Item *a) :Item_func_signed(a)
  {
    unsigned_flag= 1;
  }
  const char *func_name() const { return "cast_as_unsigned"; }
  longlong val_int();
  virtual void print(String *str, enum_query_type query_type);
};


class Item_decimal_typecast :public Item_func
{
  my_decimal decimal_value;
public:
  Item_decimal_typecast(Item *a, int len, int dec) :Item_func(a)
  {
    decimals= dec;
    max_length= my_decimal_precision_to_length_no_truncation(len, dec,
                                                             unsigned_flag);
  }
  String *val_str(String *str);
  double val_real();
  longlong val_int();
  my_decimal *val_decimal(my_decimal*);
  enum Item_result result_type () const { return DECIMAL_RESULT; }
  enum_field_types field_type() const { return MYSQL_TYPE_NEWDECIMAL; }
  void fix_length_and_dec() {};
  const char *func_name() const { return "decimal_typecast"; }
  virtual void print(String *str, enum_query_type query_type);
};


class Item_func_additive_op :public Item_num_op
{
public:
  Item_func_additive_op(Item *a,Item *b) :Item_num_op(a,b) {}
  void result_precision();
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};


class Item_func_plus :public Item_func_additive_op
{
public:
  Item_func_plus(Item *a,Item *b) :Item_func_additive_op(a,b) {}
  const char *func_name() const { return "+"; }
  longlong int_op();
  double real_op();
  my_decimal *decimal_op(my_decimal *);
};

class Item_func_minus :public Item_func_additive_op
{
public:
  Item_func_minus(Item *a,Item *b) :Item_func_additive_op(a,b) {}
  const char *func_name() const { return "-"; }
  longlong int_op();
  double real_op();
  my_decimal *decimal_op(my_decimal *);
  void fix_length_and_dec();
};


class Item_func_mul :public Item_num_op
{
public:
  Item_func_mul(Item *a,Item *b) :Item_num_op(a,b) {}
  const char *func_name() const { return "*"; }
  longlong int_op();
  double real_op();
  my_decimal *decimal_op(my_decimal *);
  void result_precision();
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};


class Item_func_div :public Item_num_op
{
public:
  uint prec_increment;
  Item_func_div(Item *a,Item *b) :Item_num_op(a,b) {}
  longlong int_op() { DBUG_ASSERT(0); return 0; }
  double real_op();
  my_decimal *decimal_op(my_decimal *);
  const char *func_name() const { return "/"; }
  void fix_length_and_dec();
  void result_precision();
};


class Item_func_int_div :public Item_int_func
{
public:
  Item_func_int_div(Item *a,Item *b) :Item_int_func(a,b)
  {}
  longlong val_int();
  const char *func_name() const { return "DIV"; }
  void fix_length_and_dec();

  virtual inline void print(String *str, enum_query_type query_type)
  {
    print_op(str, query_type);
  }

  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};


class Item_func_mod :public Item_num_op
{
public:
  Item_func_mod(Item *a,Item *b) :Item_num_op(a,b) {}
  longlong int_op();
  double real_op();
  my_decimal *decimal_op(my_decimal *);
  const char *func_name() const { return "%"; }
  void result_precision();
  void fix_length_and_dec();
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};


class Item_func_neg :public Item_func_num1
{
public:
  Item_func_neg(Item *a) :Item_func_num1(a) {}
  double real_op();
  longlong int_op();
  my_decimal *decimal_op(my_decimal *);
  const char *func_name() const { return "-"; }
  enum Functype functype() const   { return NEG_FUNC; }
  void fix_length_and_dec();
  void fix_num_length_and_dec();
  uint decimal_precision() const { return args[0]->decimal_precision(); }
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};


class Item_func_abs :public Item_func_num1
{
public:
  Item_func_abs(Item *a) :Item_func_num1(a) {}
  double real_op();
  longlong int_op();
  my_decimal *decimal_op(my_decimal *);
  const char *func_name() const { return "abs"; }
  void fix_length_and_dec();
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};

// A class to handle logarithmic and trigonometric functions

class Item_dec_func :public Item_real_func
{
 public:
  Item_dec_func(Item *a) :Item_real_func(a) {}
  Item_dec_func(Item *a,Item *b) :Item_real_func(a,b) {}
  void fix_length_and_dec()
  {
    decimals=NOT_FIXED_DEC; max_length=float_length(decimals);
    maybe_null=1;
  }
};

class Item_func_exp :public Item_dec_func
{
public:
  Item_func_exp(Item *a) :Item_dec_func(a) {}
  double val_real();
  const char *func_name() const { return "exp"; }
};


class Item_func_ln :public Item_dec_func
{
public:
  Item_func_ln(Item *a) :Item_dec_func(a) {}
  double val_real();
  const char *func_name() const { return "ln"; }
};


class Item_func_log :public Item_dec_func
{
public:
  Item_func_log(Item *a) :Item_dec_func(a) {}
  Item_func_log(Item *a,Item *b) :Item_dec_func(a,b) {}
  double val_real();
  const char *func_name() const { return "log"; }
};


class Item_func_log2 :public Item_dec_func
{
public:
  Item_func_log2(Item *a) :Item_dec_func(a) {}
  double val_real();
  const char *func_name() const { return "log2"; }
};


class Item_func_log10 :public Item_dec_func
{
public:
  Item_func_log10(Item *a) :Item_dec_func(a) {}
  double val_real();
  const char *func_name() const { return "log10"; }
};


class Item_func_sqrt :public Item_dec_func
{
public:
  Item_func_sqrt(Item *a) :Item_dec_func(a) {}
  double val_real();
  const char *func_name() const { return "sqrt"; }
};


class Item_func_pow :public Item_dec_func
{
public:
  Item_func_pow(Item *a,Item *b) :Item_dec_func(a,b) {}
  double val_real();
  const char *func_name() const { return "pow"; }
};


class Item_func_acos :public Item_dec_func
{
public:
  Item_func_acos(Item *a) :Item_dec_func(a) {}
  double val_real();
  const char *func_name() const { return "acos"; }
};

class Item_func_asin :public Item_dec_func
{
public:
  Item_func_asin(Item *a) :Item_dec_func(a) {}
  double val_real();
  const char *func_name() const { return "asin"; }
};

class Item_func_atan :public Item_dec_func
{
public:
  Item_func_atan(Item *a) :Item_dec_func(a) {}
  Item_func_atan(Item *a,Item *b) :Item_dec_func(a,b) {}
  double val_real();
  const char *func_name() const { return "atan"; }
};

class Item_func_cos :public Item_dec_func
{
public:
  Item_func_cos(Item *a) :Item_dec_func(a) {}
  double val_real();
  const char *func_name() const { return "cos"; }
};

class Item_func_sin :public Item_dec_func
{
public:
  Item_func_sin(Item *a) :Item_dec_func(a) {}
  double val_real();
  const char *func_name() const { return "sin"; }
};

class Item_func_tan :public Item_dec_func
{
public:
  Item_func_tan(Item *a) :Item_dec_func(a) {}
  double val_real();
  const char *func_name() const { return "tan"; }
};

class Item_func_integer :public Item_int_func
{
public:
  inline Item_func_integer(Item *a) :Item_int_func(a) {}
  void fix_length_and_dec();
};


class Item_func_int_val :public Item_func_num1
{
public:
  Item_func_int_val(Item *a) :Item_func_num1(a) {}
  void fix_num_length_and_dec();
  void find_num_type();
};


class Item_func_ceiling :public Item_func_int_val
{
public:
  Item_func_ceiling(Item *a) :Item_func_int_val(a) {}
  const char *func_name() const { return "ceiling"; }
  longlong int_op();
  double real_op();
  my_decimal *decimal_op(my_decimal *);
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};


class Item_func_floor :public Item_func_int_val
{
public:
  Item_func_floor(Item *a) :Item_func_int_val(a) {}
  const char *func_name() const { return "floor"; }
  longlong int_op();
  double real_op();
  my_decimal *decimal_op(my_decimal *);
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};

/* This handles round and truncate */

class Item_func_round :public Item_func_num1
{
  bool truncate;
public:
  Item_func_round(Item *a, Item *b, bool trunc_arg)
    :Item_func_num1(a,b), truncate(trunc_arg) {}
  const char *func_name() const { return truncate ? "truncate" : "round"; }
  double real_op();
  longlong int_op();
  my_decimal *decimal_op(my_decimal *);
  void fix_length_and_dec();
};


class Item_func_rand :public Item_real_func
{
  struct rand_struct *rand;
  bool first_eval; // TRUE if val_real() is called 1st time
public:
  Item_func_rand(Item *a) :Item_real_func(a), rand(0), first_eval(TRUE) {}
  Item_func_rand()	  :Item_real_func() {}
  double val_real();
  const char *func_name() const { return "rand"; }
  bool const_item() const { return 0; }
  void update_used_tables();
  bool fix_fields(THD *thd, Item **ref);
  void cleanup() { first_eval= TRUE; Item_real_func::cleanup(); }
private:
  void seed_random (Item * val);  
};


class Item_func_sign :public Item_int_func
{
public:
  Item_func_sign(Item *a) :Item_int_func(a) {}
  const char *func_name() const { return "sign"; }
  longlong val_int();
};


class Item_func_units :public Item_real_func
{
  char *name;
  double mul,add;
public:
  Item_func_units(char *name_arg,Item *a,double mul_arg,double add_arg)
    :Item_real_func(a),name(name_arg),mul(mul_arg),add(add_arg) {}
  double val_real();
  const char *func_name() const { return name; }
  void fix_length_and_dec()
  { decimals= NOT_FIXED_DEC; max_length= float_length(decimals); }
};


class Item_func_min_max :public Item_func
{
  Item_result cmp_type;
  String tmp_value;
  int cmp_sign;
  /* TRUE <=> arguments should be compared in the DATETIME context. */
  bool compare_as_dates;
  /* An item used for issuing warnings while string to DATETIME conversion. */
  Item *datetime_item;
  THD *thd;
protected:
  enum_field_types cached_field_type;
public:
  Item_func_min_max(List<Item> &list,int cmp_sign_arg) :Item_func(list),
    cmp_type(INT_RESULT), cmp_sign(cmp_sign_arg), compare_as_dates(FALSE),
    datetime_item(0) {}
  double val_real();
  longlong val_int();
  String *val_str(String *);
  my_decimal *val_decimal(my_decimal *);
  void fix_length_and_dec();
  enum Item_result result_type () const { return cmp_type; }
  bool result_as_longlong() { return compare_as_dates; };
  uint cmp_datetimes(ulonglong *value);
  enum_field_types field_type() const { return cached_field_type; }
};

class Item_func_min :public Item_func_min_max
{
public:
  Item_func_min(List<Item> &list) :Item_func_min_max(list,1) {}
  const char *func_name() const { return "least"; }
};

class Item_func_max :public Item_func_min_max
{
public:
  Item_func_max(List<Item> &list) :Item_func_min_max(list,-1) {}
  const char *func_name() const { return "greatest"; }
};


/* 
  Objects of this class are used for ROLLUP queries to wrap up 
  each constant item referred to in GROUP BY list. 
*/

class Item_func_rollup_const :public Item_func
{
public:
  Item_func_rollup_const(Item *a) :Item_func(a)
  {
    name= a->name;
    name_length= a->name_length;
  }
  double val_real() { return args[0]->val_real(); }
  longlong val_int() { return args[0]->val_int(); }
  String *val_str(String *str) { return args[0]->val_str(str); }
  my_decimal *val_decimal(my_decimal *dec) { return args[0]->val_decimal(dec); }
  const char *func_name() const { return "rollup_const"; }
  bool const_item() const { return 0; }
  Item_result result_type() const { return args[0]->result_type(); }
  void fix_length_and_dec()
  {
    collation= args[0]->collation;
    max_length= args[0]->max_length;
    decimals=args[0]->decimals; 
    /* The item could be a NULL constant. */
    null_value= args[0]->is_null();
  }
};


class Item_func_length :public Item_int_func
{
  String value;
public:
  Item_func_length(Item *a) :Item_int_func(a) {}
  longlong val_int();
  const char *func_name() const { return "length"; }
  void fix_length_and_dec() { max_length=10; }
};

class Item_func_bit_length :public Item_func_length
{
public:
  Item_func_bit_length(Item *a) :Item_func_length(a) {}
  longlong val_int()
    { DBUG_ASSERT(fixed == 1); return Item_func_length::val_int()*8; }
  const char *func_name() const { return "bit_length"; }
};

class Item_func_char_length :public Item_int_func
{
  String value;
public:
  Item_func_char_length(Item *a) :Item_int_func(a) {}
  longlong val_int();
  const char *func_name() const { return "char_length"; }
  void fix_length_and_dec() { max_length=10; }
};

class Item_func_coercibility :public Item_int_func
{
public:
  Item_func_coercibility(Item *a) :Item_int_func(a) {}
  longlong val_int();
  const char *func_name() const { return "coercibility"; }
  void fix_length_and_dec() { max_length=10; maybe_null= 0; }
  table_map not_null_tables() const { return 0; }
};

class Item_func_locate :public Item_int_func
{
  String value1,value2;
  DTCollation cmp_collation;
public:
  Item_func_locate(Item *a,Item *b) :Item_int_func(a,b) {}
  Item_func_locate(Item *a,Item *b,Item *c) :Item_int_func(a,b,c) {}
  const char *func_name() const { return "locate"; }
  longlong val_int();
  void fix_length_and_dec();
  virtual void print(String *str, enum_query_type query_type);
};


class Item_func_field :public Item_int_func
{
  String value,tmp;
  Item_result cmp_type;
  DTCollation cmp_collation;
public:
  Item_func_field(List<Item> &list) :Item_int_func(list) {}
  longlong val_int();
  const char *func_name() const { return "field"; }
  void fix_length_and_dec();
};


class Item_func_ascii :public Item_int_func
{
  String value;
public:
  Item_func_ascii(Item *a) :Item_int_func(a) {}
  longlong val_int();
  const char *func_name() const { return "ascii"; }
  void fix_length_and_dec() { max_length=3; }
};

class Item_func_ord :public Item_int_func
{
  String value;
public:
  Item_func_ord(Item *a) :Item_int_func(a) {}
  longlong val_int();
  const char *func_name() const { return "ord"; }
};

class Item_func_find_in_set :public Item_int_func
{
  String value,value2;
  uint enum_value;
  ulonglong enum_bit;
  DTCollation cmp_collation;
public:
  Item_func_find_in_set(Item *a,Item *b) :Item_int_func(a,b),enum_value(0) {}
  longlong val_int();
  const char *func_name() const { return "find_in_set"; }
  void fix_length_and_dec();
};

/* Base class for all bit functions: '~', '|', '^', '&', '>>', '<<' */

class Item_func_bit: public Item_int_func
{
public:
  Item_func_bit(Item *a, Item *b) :Item_int_func(a, b) {}
  Item_func_bit(Item *a) :Item_int_func(a) {}
  void fix_length_and_dec() { unsigned_flag= 1; }

  virtual inline void print(String *str, enum_query_type query_type)
  {
    print_op(str, query_type);
  }
};

class Item_func_bit_or :public Item_func_bit
{
public:
  Item_func_bit_or(Item *a, Item *b) :Item_func_bit(a, b) {}
  longlong val_int();
  const char *func_name() const { return "|"; }
};

class Item_func_bit_and :public Item_func_bit
{
public:
  Item_func_bit_and(Item *a, Item *b) :Item_func_bit(a, b) {}
  longlong val_int();
  const char *func_name() const { return "&"; }
};

class Item_func_bit_count :public Item_int_func
{
public:
  Item_func_bit_count(Item *a) :Item_int_func(a) {}
  longlong val_int();
  const char *func_name() const { return "bit_count"; }
  void fix_length_and_dec() { max_length=2; }
};

class Item_func_shift_left :public Item_func_bit
{
public:
  Item_func_shift_left(Item *a, Item *b) :Item_func_bit(a, b) {}
  longlong val_int();
  const char *func_name() const { return "<<"; }
};

class Item_func_shift_right :public Item_func_bit
{
public:
  Item_func_shift_right(Item *a, Item *b) :Item_func_bit(a, b) {}
  longlong val_int();
  const char *func_name() const { return ">>"; }
};

class Item_func_bit_neg :public Item_func_bit
{
public:
  Item_func_bit_neg(Item *a) :Item_func_bit(a) {}
  longlong val_int();
  const char *func_name() const { return "~"; }

  virtual inline void print(String *str, enum_query_type query_type)
  {
    Item_func::print(str, query_type);
  }
};


class Item_func_last_insert_id :public Item_int_func
{
public:
  Item_func_last_insert_id() :Item_int_func() {}
  Item_func_last_insert_id(Item *a) :Item_int_func(a) {}
  longlong val_int();
  const char *func_name() const { return "last_insert_id"; }
  void fix_length_and_dec()
  {
    unsigned_flag= TRUE;
    if (arg_count)
      max_length= args[0]->max_length;
  }
  bool fix_fields(THD *thd, Item **ref);
};


class Item_func_benchmark :public Item_int_func
{
public:
  Item_func_benchmark(Item *count_expr, Item *expr)
    :Item_int_func(count_expr, expr)
  {}
  longlong val_int();
  const char *func_name() const { return "benchmark"; }
  void fix_length_and_dec() { max_length=1; maybe_null=0; }
  virtual void print(String *str, enum_query_type query_type);
};


class Item_func_sleep :public Item_int_func
{
public:
  Item_func_sleep(Item *a) :Item_int_func(a) {}
  bool const_item() const { return 0; }
  const char *func_name() const { return "sleep"; }
  void update_used_tables()
  {
    Item_int_func::update_used_tables();
    used_tables_cache|= RAND_TABLE_BIT;
  }
  longlong val_int();
};



#ifdef HAVE_DLOPEN

class Item_udf_func :public Item_func
{
protected:
  udf_handler udf;

public:
  Item_udf_func(udf_func *udf_arg)
    :Item_func(), udf(udf_arg) {}
  Item_udf_func(udf_func *udf_arg, List<Item> &list)
    :Item_func(list), udf(udf_arg) {}
  const char *func_name() const { return udf.name(); }
  enum Functype functype() const   { return UDF_FUNC; }
  bool fix_fields(THD *thd, Item **ref)
  {
    DBUG_ASSERT(fixed == 0);
    bool res= udf.fix_fields(thd, this, arg_count, args);
    used_tables_cache= udf.used_tables_cache;
    const_item_cache= udf.const_item_cache;
    fixed= 1;
    return res;
  }
  void update_used_tables() 
  {
    /*
      TODO: Make a member in UDF_INIT and return if a UDF is deterministic or
      not.
      Currently UDF_INIT has a member (const_item) that is an in/out 
      parameter to the init() call.
      The code in udf_handler::fix_fields also duplicates the arguments 
      handling code in Item_func::fix_fields().
      
      The lack of information if a UDF is deterministic makes writing
      a correct update_used_tables() for UDFs impossible.
      One solution to this would be :
       - Add a is_deterministic member of UDF_INIT
       - (optionally) deprecate the const_item member of UDF_INIT
       - Take away the duplicate code from udf_handler::fix_fields() and
         make Item_udf_func call Item_func::fix_fields() to process its 
         arguments as for any other function.
       - Store the deterministic flag returned by <udf>_init into the 
       udf_handler. 
       - Don't implement Item_udf_func::fix_fields, implement
       Item_udf_func::fix_length_and_dec() instead (similar to non-UDF
       functions).
       - Override Item_func::update_used_tables to call 
       Item_func::update_used_tables() and add a RAND_TABLE_BIT to the 
       result of Item_func::update_used_tables() if the UDF is 
       non-deterministic.
       - (optionally) rename RAND_TABLE_BIT to NONDETERMINISTIC_BIT to
       better describe its usage.
       
      The above would require a change of the UDF API.
      Until that change is done here's how the current code works:
      We call Item_func::update_used_tables() only when we know that
      the function depends on real non-const tables and is deterministic.
      This can be done only because we know that the optimizer will
      call update_used_tables() only when there's possibly a new const
      table. So update_used_tables() can only make a Item_func more
      constant than it is currently.
      That's why we don't need to do anything if a function is guaranteed
      to return non-constant (it's non-deterministic) or is already a
      const.
    */  
    if ((used_tables_cache & ~PSEUDO_TABLE_BITS) && 
        !(used_tables_cache & RAND_TABLE_BIT))
    {
      Item_func::update_used_tables();
      if (!const_item_cache && !used_tables_cache)
        used_tables_cache= RAND_TABLE_BIT;
    }
  }
  void cleanup();
  Item_result result_type () const { return udf.result_type(); }
  table_map not_null_tables() const { return 0; }
  bool is_expensive() { return 1; }
  virtual void print(String *str, enum_query_type query_type);
};


class Item_func_udf_float :public Item_udf_func
{
 public:
  Item_func_udf_float(udf_func *udf_arg)
    :Item_udf_func(udf_arg) {}
  Item_func_udf_float(udf_func *udf_arg,
                      List<Item> &list)
    :Item_udf_func(udf_arg, list) {}
  longlong val_int()
  {
    DBUG_ASSERT(fixed == 1);
    return (longlong) rint(Item_func_udf_float::val_real());
  }
  my_decimal *val_decimal(my_decimal *dec_buf)
  {
    double res=val_real();
    if (null_value)
      return NULL;
    double2my_decimal(E_DEC_FATAL_ERROR, res, dec_buf);
    return dec_buf;
  }
  double val_real();
  String *val_str(String *str);
  void fix_length_and_dec() { fix_num_length_and_dec(); }
};


class Item_func_udf_int :public Item_udf_func
{
public:
  Item_func_udf_int(udf_func *udf_arg)
    :Item_udf_func(udf_arg) {}
  Item_func_udf_int(udf_func *udf_arg,
                    List<Item> &list)
    :Item_udf_func(udf_arg, list) {}
  longlong val_int();
  double val_real() { return (double) Item_func_udf_int::val_int(); }
  String *val_str(String *str);
  enum Item_result result_type () const { return INT_RESULT; }
  void fix_length_and_dec() { decimals= 0; max_length= 21; }
};


class Item_func_udf_decimal :public Item_udf_func
{
public:
  Item_func_udf_decimal(udf_func *udf_arg)
    :Item_udf_func(udf_arg) {}
  Item_func_udf_decimal(udf_func *udf_arg, List<Item> &list)
    :Item_udf_func(udf_arg, list) {}
  longlong val_int();
  double val_real();
  my_decimal *val_decimal(my_decimal *);
  String *val_str(String *str);
  enum Item_result result_type () const { return DECIMAL_RESULT; }
  void fix_length_and_dec();
};


class Item_func_udf_str :public Item_udf_func
{
public:
  Item_func_udf_str(udf_func *udf_arg)
    :Item_udf_func(udf_arg) {}
  Item_func_udf_str(udf_func *udf_arg, List<Item> &list)
    :Item_udf_func(udf_arg, list) {}
  String *val_str(String *);
  double val_real()
  {
    int err_not_used;
    char *end_not_used;
    String *res;
    res= val_str(&str_value);
    return res ? my_strntod(res->charset(),(char*) res->ptr(), 
                            res->length(), &end_not_used, &err_not_used) : 0.0;
  }
  longlong val_int()
  {
    int err_not_used;
    String *res;  res=val_str(&str_value);
    return res ? my_strntoll(res->charset(),res->ptr(),res->length(),10,
                             (char**) 0, &err_not_used) : (longlong) 0;
  }
  my_decimal *val_decimal(my_decimal *dec_buf)
  {
    String *res=val_str(&str_value);
    if (!res)
      return NULL;
    string2my_decimal(E_DEC_FATAL_ERROR, res, dec_buf);
    return dec_buf;
  }
  enum Item_result result_type () const { return STRING_RESULT; }
  void fix_length_and_dec();
};

#else /* Dummy functions to get sql_yacc.cc compiled */

class Item_func_udf_float :public Item_real_func
{
 public:
  Item_func_udf_float(udf_func *udf_arg)
    :Item_real_func() {}
  Item_func_udf_float(udf_func *udf_arg, List<Item> &list)
    :Item_real_func(list) {}
  double val_real() { DBUG_ASSERT(fixed == 1); return 0.0; }
};


class Item_func_udf_int :public Item_int_func
{
public:
  Item_func_udf_int(udf_func *udf_arg)
    :Item_int_func() {}
  Item_func_udf_int(udf_func *udf_arg, List<Item> &list)
    :Item_int_func(list) {}
  longlong val_int() { DBUG_ASSERT(fixed == 1); return 0; }
};


class Item_func_udf_decimal :public Item_int_func
{
public:
  Item_func_udf_decimal(udf_func *udf_arg)
    :Item_int_func() {}
  Item_func_udf_decimal(udf_func *udf_arg, List<Item> &list)
    :Item_int_func(list) {}
  my_decimal *val_decimal(my_decimal *) { DBUG_ASSERT(fixed == 1); return 0; }
};


class Item_func_udf_str :public Item_func
{
public:
  Item_func_udf_str(udf_func *udf_arg)
    :Item_func() {}
  Item_func_udf_str(udf_func *udf_arg, List<Item> &list)
    :Item_func(list) {}
  String *val_str(String *)
    { DBUG_ASSERT(fixed == 1); null_value=1; return 0; }
  double val_real() { DBUG_ASSERT(fixed == 1); null_value= 1; return 0.0; }
  longlong val_int() { DBUG_ASSERT(fixed == 1); null_value=1; return 0; }
  enum Item_result result_type () const { return STRING_RESULT; }
  void fix_length_and_dec() { maybe_null=1; max_length=0; }
};

#endif /* HAVE_DLOPEN */

/*
** User level locks
*/

class User_level_lock;
void item_user_lock_init(void);
void item_user_lock_release(User_level_lock *ull);
void item_user_lock_free(void);

class Item_func_get_lock :public Item_int_func
{
  String value;
 public:
  Item_func_get_lock(Item *a,Item *b) :Item_int_func(a,b) {}
  longlong val_int();
  const char *func_name() const { return "get_lock"; }
  void fix_length_and_dec() { max_length=1; maybe_null=1;}
};

class Item_func_release_lock :public Item_int_func
{
  String value;
public:
  Item_func_release_lock(Item *a) :Item_int_func(a) {}
  longlong val_int();
  const char *func_name() const { return "release_lock"; }
  void fix_length_and_dec() { max_length=1; maybe_null=1;}
};

/* replication functions */

class Item_master_pos_wait :public Item_int_func
{
  String value;
public:
  Item_master_pos_wait(Item *a,Item *b) :Item_int_func(a,b) {}
  Item_master_pos_wait(Item *a,Item *b,Item *c) :Item_int_func(a,b,c) {}
  longlong val_int();
  const char *func_name() const { return "master_pos_wait"; }
  void fix_length_and_dec() { max_length=21; maybe_null=1;}
};


/* Handling of user definable variables */

class user_var_entry;

class Item_func_set_user_var :public Item_func
{
  enum Item_result cached_result_type;
  user_var_entry *entry;
  /*
    The entry_thread_id variable is used:
    1) to skip unnecessary updates of the entry field (see above);
    2) to reset the entry field that was initialized in the other thread
       (for example, an item tree of a trigger that updates user variables
       may be shared between several connections, and the entry_thread_id field
       prevents updates of one connection user variables from a concurrent
       connection calling the same trigger that initially updated some
       user variable it the first connection context).
  */
  my_thread_id entry_thread_id;
  char buffer[MAX_FIELD_WIDTH];
  String value;
  my_decimal decimal_buff;
  bool null_item;
  union
  {
    longlong vint;
    double vreal;
    String *vstr;
    my_decimal *vdec;
  } save_result;

public:
  LEX_STRING name; // keep it public
  Item_func_set_user_var(LEX_STRING a,Item *b)
    :Item_func(b), cached_result_type(INT_RESULT),
     entry(NULL), entry_thread_id(0), name(a)
  {}
  enum Functype functype() const { return SUSERVAR_FUNC; }
  double val_real();
  longlong val_int();
  String *val_str(String *str);
  my_decimal *val_decimal(my_decimal *);
  double val_result();
  longlong val_int_result();
  bool val_bool_result();
  String *str_result(String *str);
  my_decimal *val_decimal_result(my_decimal *);
  bool is_null_result();
  bool update_hash(void *ptr, uint length, enum Item_result type,
  		   CHARSET_INFO *cs, Derivation dv, bool unsigned_arg);
  bool send(Protocol *protocol, String *str_arg);
  void make_field(Send_field *tmp_field);
  bool check(bool use_result_field);
  void save_item_result(Item *item);
  bool update();
  enum Item_result result_type () const { return cached_result_type; }
  bool fix_fields(THD *thd, Item **ref);
  void fix_length_and_dec();
  virtual void print(String *str, enum_query_type query_type);
  void print_as_stmt(String *str, enum_query_type query_type);
  const char *func_name() const { return "set_user_var"; }
  int save_in_field(Field *field, bool no_conversions,
                    bool can_use_result_field);
  int save_in_field(Field *field, bool no_conversions)
  {
    return save_in_field(field, no_conversions, 1);
  }
  void save_org_in_field(Field *field) { (void)save_in_field(field, 1, 0); }
  bool register_field_in_read_map(uchar *arg);
  bool set_entry(THD *thd, bool create_if_not_exists);
  void cleanup();
};


class Item_func_get_user_var :public Item_func,
                              private Settable_routine_parameter
{
  user_var_entry *var_entry;
  Item_result m_cached_result_type;

public:
  LEX_STRING name; // keep it public
  Item_func_get_user_var(LEX_STRING a):
    Item_func(), m_cached_result_type(STRING_RESULT), name(a) {}
  enum Functype functype() const { return GUSERVAR_FUNC; }
  LEX_STRING get_name() { return name; }
  double val_real();
  longlong val_int();
  my_decimal *val_decimal(my_decimal*);
  String *val_str(String* str);
  void fix_length_and_dec();
  virtual void print(String *str, enum_query_type query_type);
  enum Item_result result_type() const;
  /*
    We must always return variables as strings to guard against selects of type
    select @t1:=1,@t1,@t:="hello",@t from foo where (@t1:= t2.b)
  */
  const char *func_name() const { return "get_user_var"; }
  bool const_item() const;
  table_map used_tables() const
  { return const_item() ? 0 : RAND_TABLE_BIT; }
  bool eq(const Item *item, bool binary_cmp) const;
private:
  bool set_value(THD *thd, sp_rcontext *ctx, Item **it);

public:
  Settable_routine_parameter *get_settable_routine_parameter()
  {
    return this;
  }
};


/*
  This item represents user variable used as out parameter (e.g in LOAD DATA),
  and it is supposed to be used only for this purprose. So it is simplified
  a lot. Actually you should never obtain its value.

  The only two reasons for this thing being an Item is possibility to store it
  in List<Item> and desire to place this code somewhere near other functions
  working with user variables.
*/
class Item_user_var_as_out_param :public Item
{
  LEX_STRING name;
  user_var_entry *entry;
public:
  Item_user_var_as_out_param(LEX_STRING a) : name(a) {}
  /* We should return something different from FIELD_ITEM here */
  enum Type type() const { return STRING_ITEM;}
  double val_real();
  longlong val_int();
  String *val_str(String *str);
  my_decimal *val_decimal(my_decimal *decimal_buffer);
  /* fix_fields() binds variable name with its entry structure */
  bool fix_fields(THD *thd, Item **ref);
  virtual void print(String *str, enum_query_type query_type);
  void set_null_value(CHARSET_INFO* cs);
  void set_value(const char *str, uint length, CHARSET_INFO* cs);
};


/* A system variable */

#define GET_SYS_VAR_CACHE_LONG     1
#define GET_SYS_VAR_CACHE_DOUBLE   2
#define GET_SYS_VAR_CACHE_STRING   4

class Item_func_get_system_var :public Item_func
{
  sys_var *var;
  enum_var_type var_type, orig_var_type;
  LEX_STRING component;
  longlong cached_llval;
  double cached_dval;
  String cached_strval;
  my_bool cached_null_value;
  query_id_t used_query_id;
  uchar cache_present;

public:
  Item_func_get_system_var(sys_var *var_arg, enum_var_type var_type_arg,
                           LEX_STRING *component_arg, const char *name_arg,
                           size_t name_len_arg);
  enum Functype functype() const { return GSYSVAR_FUNC; }
  void update_null_value();
  void fix_length_and_dec();
  void print(String *str, enum_query_type query_type);
  bool const_item() const { return true; }
  table_map used_tables() const { return 0; }
  enum Item_result result_type() const;
  enum_field_types field_type() const;
  double val_real();
  longlong val_int();
  String* val_str(String*);
  /* TODO: fix to support views */
  const char *func_name() const { return "get_system_var"; }
  /**
    Indicates whether this system variable is written to the binlog or not.

    Variables are written to the binlog as part of "status_vars" in
    Query_log_event, as an Intvar_log_event, or a Rand_log_event.

    @return true if the variable is written to the binlog, false otherwise.
  */
  bool is_written_to_binlog();
  bool eq(const Item *item, bool binary_cmp) const;

  void cleanup();
};


class Item_func_inet_aton : public Item_int_func
{
public:
  Item_func_inet_aton(Item *a) :Item_int_func(a) {}
  longlong val_int();
  const char *func_name() const { return "inet_aton"; }
  void fix_length_and_dec() { decimals= 0; max_length= 21; maybe_null= 1; unsigned_flag= 1;}
};


/* for fulltext search */
#include <ft_global.h>

class Item_func_match :public Item_real_func
{
public:
  uint key, flags;
  bool join_key;
  DTCollation cmp_collation;
  FT_INFO *ft_handler;
  TABLE *table;
  Item_func_match *master;   // for master-slave optimization
  Item *concat_ws;           // Item_func_concat_ws
  String value;              // value of concat_ws
  String search_value;       // key_item()'s value converted to cmp_collation

  Item_func_match(List<Item> &a, uint b): Item_real_func(a), key(0), flags(b),
       join_key(0), ft_handler(0), table(0), master(0), concat_ws(0) { }
  void cleanup()
  {
    DBUG_ENTER("Item_func_match::cleanup");
    Item_real_func::cleanup();
    if (!master && ft_handler)
      ft_handler->please->close_search(ft_handler);
    ft_handler= 0;
    concat_ws= 0;
    table= 0;           // required by Item_func_match::eq()
    DBUG_VOID_RETURN;
  }
  enum Functype functype() const { return FT_FUNC; }
  const char *func_name() const { return "match"; }
  void update_used_tables() {}
  table_map not_null_tables() const { return 0; }
  bool fix_fields(THD *thd, Item **ref);
  bool eq(const Item *, bool binary_cmp) const;
  /* The following should be safe, even if we compare doubles */
  longlong val_int() { DBUG_ASSERT(fixed == 1); return val_real() != 0.0; }
  double val_real();
  virtual void print(String *str, enum_query_type query_type);

  bool fix_index();
  void init_search(bool no_order);
};


class Item_func_bit_xor : public Item_func_bit
{
public:
  Item_func_bit_xor(Item *a, Item *b) :Item_func_bit(a, b) {}
  longlong val_int();
  const char *func_name() const { return "^"; }
};

class Item_func_is_free_lock :public Item_int_func
{
  String value;
public:
  Item_func_is_free_lock(Item *a) :Item_int_func(a) {}
  longlong val_int();
  const char *func_name() const { return "is_free_lock"; }
  void fix_length_and_dec() { decimals=0; max_length=1; maybe_null=1;}
};

class Item_func_is_used_lock :public Item_int_func
{
  String value;
public:
  Item_func_is_used_lock(Item *a) :Item_int_func(a) {}
  longlong val_int();
  const char *func_name() const { return "is_used_lock"; }
  void fix_length_and_dec() { decimals=0; max_length=10; maybe_null=1;}
};

/* For type casts */

enum Cast_target
{
  ITEM_CAST_BINARY, ITEM_CAST_SIGNED_INT, ITEM_CAST_UNSIGNED_INT,
  ITEM_CAST_DATE, ITEM_CAST_TIME, ITEM_CAST_DATETIME, ITEM_CAST_CHAR,
  ITEM_CAST_DECIMAL
};


class Item_func_row_count :public Item_int_func
{
public:
  Item_func_row_count() :Item_int_func() {}
  longlong val_int();
  const char *func_name() const { return "row_count"; }
  void fix_length_and_dec() { decimals= 0; maybe_null=0; }
};


/*
 *
 * Stored FUNCTIONs
 *
 */

class sp_head;
class sp_name;
struct st_sp_security_context;

class Item_func_sp :public Item_func
{
private:
  Name_resolution_context *context;
  sp_name *m_name;
  mutable sp_head *m_sp;
  TABLE *dummy_table;
  uchar result_buf[64];
  /*
     The result field of the concrete stored function.
  */
  Field *sp_result_field;

  bool execute();
  bool execute_impl(THD *thd);
  bool init_result_field(THD *thd);
  
public:

  Item_func_sp(Name_resolution_context *context_arg, sp_name *name);

  Item_func_sp(Name_resolution_context *context_arg,
               sp_name *name, List<Item> &list);

  virtual ~Item_func_sp()
  {}

  void update_used_tables();

  void cleanup();

  const char *func_name() const;

  enum enum_field_types field_type() const;

  Field *tmp_table_field(TABLE *t_arg);

  void make_field(Send_field *tmp_field);

  Item_result result_type() const;

  longlong val_int()
  {
    if (execute())
      return (longlong) 0;
    return sp_result_field->val_int();
  }

  double val_real()
  {
    if (execute())
      return 0.0;
    return sp_result_field->val_real();
  }

  my_decimal *val_decimal(my_decimal *dec_buf)
  {
    if (execute())
      return NULL;
    return sp_result_field->val_decimal(dec_buf);
  }

  String *val_str(String *str)
  {
    String buf;
    char buff[20];
    buf.set(buff, 20, str->charset());
    buf.length(0);
    if (execute())
      return NULL;
    /*
      result_field will set buf pointing to internal buffer
      of the resul_field. Due to this it will change any time
      when SP is executed. In order to prevent occasional
      corruption of returned value, we make here a copy.
    */
    sp_result_field->val_str(&buf);
    str->copy(buf);
    return str;
  }

  virtual bool change_context_processor(uchar *cntx)
    { context= (Name_resolution_context *)cntx; return FALSE; }

  bool sp_check_access(THD * thd);
  virtual enum Functype functype() const { return FUNC_SP; }

  bool fix_fields(THD *thd, Item **ref);
  void fix_length_and_dec(void);
  bool is_expensive() { return 1; }

  inline Field *get_sp_result_field()
  {
    return sp_result_field;
  }
};


class Item_func_found_rows :public Item_int_func
{
public:
  Item_func_found_rows() :Item_int_func() {}
  longlong val_int();
  const char *func_name() const { return "found_rows"; }
  void fix_length_and_dec() { decimals= 0; maybe_null=0; }
};


void uuid_short_init();

class Item_func_uuid_short :public Item_int_func
{
public:
  Item_func_uuid_short() :Item_int_func() {}
  const char *func_name() const { return "uuid_short"; }
  longlong val_int();
  void fix_length_and_dec()
  { max_length= 21; unsigned_flag=1; }
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};