item_func.h

/* Copyright (C) 2000-2006 MySQL 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; 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  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 };
  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]; }
  /*
    This method is used for debug purposes to print the name of an
    item to the debug log. The second use of this method is as
    a helper function of print(), where it is applicable.
    To suit both goals it should return a meaningful,
    distinguishable and sintactically correct string.  This method
    should not be used for runtime type identification, use enum
    {Sum}Functype and Item_func::functype()/Item_sum::sum_func()
    instead.
  */
  virtual const char *func_name() const= 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);
  void print(String *str);
  void print_op(String *str);
  void print_args(String *str, uint from);
  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; }
};


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);

  virtual longlong int_op()= 0;
  virtual double real_op()= 0;
  virtual my_decimal *decimal_op(my_decimal *)= 0;
  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; }
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};


/* 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;
  void print(String *str) { print_op(str); }
  void find_num_type();
  String *str_op(String *str) { DBUG_ASSERT(0); return 0; }
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};


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) {}
  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=args[0]->max_length; unsigned_flag=0; }
  void print(String *str);
  uint decimal_precision() const { return args[0]->decimal_precision(); }
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};


class Item_func_unsigned :public Item_func_signed
{
public:
  Item_func_unsigned(Item *a) :Item_func_signed(a) {}
  const char *func_name() const { return "cast_as_unsigned"; }
  void fix_length_and_dec()
  { max_length=args[0]->max_length; unsigned_flag=1; }
  longlong val_int();
  void print(String *str);
};


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(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"; }
  void print(String *);
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};


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();
};


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();
};


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();
  void print(String *str) { print_op(str); }
  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();
};


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 "-"; }
  void fix_length_and_dec();
  void fix_num_length_and_dec();
  uint decimal_precision() const { return args[0]->decimal_precision(); }
};


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();
};

// 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;
  }
  inline double fix_result(double value)
  {
#ifndef HAVE_FINITE
    return value;
#else
    /* The following should be safe, even if we compare doubles */
    if (finite(value) && value != POSTFIX_ERROR)
      return value;
    null_value=1;
    return 0.0;
#endif
  }
};

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


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


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


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


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


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


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


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

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

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

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

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

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

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 *);
};


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 *);
};

/* 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;
public:
  Item_func_rand(Item *a) :Item_real_func(a), rand(0) {}
  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);
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();
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};


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


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;

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; };
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
  uint cmp_datetimes(ulonglong *value);
};

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; 
  }
};


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

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

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();
  void print(String *str);
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};


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

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

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

/* 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; }
  void print(String *str) { print_op(str); }
  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
};

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

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 "~"; }
  void print(String *str) { Item_func::print(str); }
};


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()
  {
    if (arg_count)
      max_length= args[0]->max_length;
  }
};


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; }
  void print(String *str);
};


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 cleanup();
  Item_result result_type () const { return udf.result_type(); }
  table_map not_null_tables() const { return 0; }
  bool is_expensive() { return 1; }
  void print(String *str);
};


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;
  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), 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 *);
  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);
  bool update();
  enum Item_result result_type () const { return cached_result_type; }
  bool fix_fields(THD *thd, Item **ref);
  void fix_length_and_dec();
  void print(String *str);
  void print_as_stmt(String *str);
  const char *func_name() const { return "set_user_var"; }
  int save_in_field(Field *field, bool no_conversions);
};


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();
  void print(String *str);
  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);
  void print(String *str);
  void set_null_value(CHARSET_INFO* cs);
  void set_value(const char *str, uint length, CHARSET_INFO* cs);
};


/* A system variable */

class Item_func_get_system_var :public Item_func
{
  sys_var *var;
  enum_var_type var_type;
  LEX_STRING component;
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);
  bool fix_fields(THD *thd, Item **ref);
  /*
    Stubs for pure virtual methods. Should never be called: this
    item is always substituted with a constant in fix_fields().
  */
  double val_real()         { DBUG_ASSERT(0); return 0.0; }
  longlong val_int()        { DBUG_ASSERT(0); return 0; }
  String* val_str(String*)  { DBUG_ASSERT(0); return 0; }
  void fix_length_and_dec() { DBUG_ASSERT(0); }
  /* TODO: fix to support views */
  const char *func_name() const { return "get_system_var"; }
};


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


/* 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");
    Item_real_func::cleanup();
    if (!master && ft_handler)
      ft_handler->please->close_search(ft_handler);
    ft_handler= 0;
    concat_ws= 0;
    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();
  void print(String *str);

  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()
  {}

  table_map used_tables() const { return RAND_TABLE_BIT; }

  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; }
};


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;}
};