~drizzle-trunk/drizzle/development : contents of drizzled/item

~drizzle-trunk/drizzle/development : (revision 520.4.42)
/** Copyright (C) 2000-2003 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 */


/**
  @file

  @brief
  This file defines all numerical functions
*/

#include <drizzled/server_includes.h>
#include <mysys/my_bit.h>
#include <drizzled/slave.h>
#include <drizzled/error.h>

bool check_reserved_words(LEX_STRING *name)
{
  if (!my_strcasecmp(system_charset_info, name->str, "GLOBAL") ||
      !my_strcasecmp(system_charset_info, name->str, "LOCAL") ||
      !my_strcasecmp(system_charset_info, name->str, "SESSION"))
    return true;
  return false;
}


/**
  @return
    true if item is a constant
*/

bool
eval_const_cond(COND *cond)
{
  return ((Item_func*) cond)->val_int() ? true : false;
}


void Item_func::fix_num_length_and_dec()
{
  uint32_t fl_length= 0;
  decimals=0;
  for (uint32_t i=0 ; i < arg_count ; i++)
  {
    set_if_bigger(decimals,args[i]->decimals);
    set_if_bigger(fl_length, args[i]->max_length);
  }
  max_length=float_length(decimals);
  if (fl_length > max_length)
  {
    decimals= NOT_FIXED_DEC;
    max_length= float_length(NOT_FIXED_DEC);
  }
}

/**
  Set max_length/decimals of function if function is fixed point and
  result length/precision depends on argument ones.
*/

void Item_func::count_decimal_length()
{
  int max_int_part= 0;
  decimals= 0;
  unsigned_flag= 1;
  for (uint32_t i=0 ; i < arg_count ; i++)
  {
    set_if_bigger(decimals, args[i]->decimals);
    set_if_bigger(max_int_part, args[i]->decimal_int_part());
    set_if_smaller(unsigned_flag, args[i]->unsigned_flag);
  }
  int precision= cmin(max_int_part + decimals, DECIMAL_MAX_PRECISION);
  max_length= my_decimal_precision_to_length(precision, decimals,
                                             unsigned_flag);
}


/**
  Set max_length of if it is maximum length of its arguments.
*/

void Item_func::count_only_length()
{
  max_length= 0;
  unsigned_flag= 0;
  for (uint32_t i=0 ; i < arg_count ; i++)
  {
    set_if_bigger(max_length, args[i]->max_length);
    set_if_bigger(unsigned_flag, args[i]->unsigned_flag);
  }
}


/**
  Set max_length/decimals of function if function is floating point and
  result length/precision depends on argument ones.
*/

void Item_func::count_real_length()
{
  uint32_t length= 0;
  decimals= 0;
  max_length= 0;
  for (uint32_t i=0 ; i < arg_count ; i++)
  {
    if (decimals != NOT_FIXED_DEC)
    {
      set_if_bigger(decimals, args[i]->decimals);
      set_if_bigger(length, (args[i]->max_length - args[i]->decimals));
    }
    set_if_bigger(max_length, args[i]->max_length);
  }
  if (decimals != NOT_FIXED_DEC)
  {
    max_length= length;
    length+= decimals;
    if (length < max_length)  // If previous operation gave overflow
      max_length= UINT32_MAX;
    else
      max_length= length;
  }
}



void Item_func::signal_divide_by_null()
{
  Session *session= current_session;
  push_warning(session, DRIZZLE_ERROR::WARN_LEVEL_ERROR, ER_DIVISION_BY_ZERO, ER(ER_DIVISION_BY_ZERO));
  null_value= 1;
}


Item *Item_func::get_tmp_table_item(Session *session)
{
  if (!with_sum_func && !const_item() && functype() != SUSERVAR_FUNC)
    return new Item_field(result_field);
  return copy_or_same(session);
}

/*
  When a user variable is updated (in a SET command or a query like
  SELECT @a:= ).
*/

bool Item_func_set_user_var::fix_fields(Session *session, Item **ref)
{
  assert(fixed == 0);
  /* fix_fields will call Item_func_set_user_var::fix_length_and_dec */
  if (Item_func::fix_fields(session, ref) ||
      !(entry= get_variable(&session->user_vars, name, 1)))
    return true;
  /* 
     Remember the last query which updated it, this way a query can later know
     if this variable is a constant item in the query (it is if update_query_id
     is different from query_id).
  */
  entry->update_query_id= session->query_id;
  /*
    As it is wrong and confusing to associate any 
    character set with NULL, @a should be latin2
    after this query sequence:

      SET @a=_latin2'string';
      SET @a=NULL;

    I.e. the second query should not change the charset
    to the current default value, but should keep the 
    original value assigned during the first query.
    In order to do it, we don't copy charset
    from the argument if the argument is NULL
    and the variable has previously been initialized.
  */
  null_item= (args[0]->type() == NULL_ITEM);
  if (!entry->collation.collation || !null_item)
    entry->collation.set(args[0]->collation.collation, DERIVATION_IMPLICIT);
  collation.set(entry->collation.collation, DERIVATION_IMPLICIT);
  cached_result_type= args[0]->result_type();
  return false;
}


void
Item_func_set_user_var::fix_length_and_dec()
{
  maybe_null=args[0]->maybe_null;
  max_length=args[0]->max_length;
  decimals=args[0]->decimals;
  collation.set(args[0]->collation.collation, DERIVATION_IMPLICIT);
}


/*
  Mark field in read_map

  NOTES
    This is used by filesort to register used fields in a a temporary
    column read set or to register used fields in a view
*/

bool Item_func_set_user_var::register_field_in_read_map(unsigned char *arg)
{
  if (result_field)
  {
    Table *table= (Table *) arg;
    if (result_field->table == table || !table)
      bitmap_set_bit(result_field->table->read_set, result_field->field_index);
    if (result_field->vcol_info && result_field->vcol_info->expr_item)
      return result_field->vcol_info->
               expr_item->walk(&Item::register_field_in_read_map, 1, arg);
  }
  return 0;
}


/*
  Mark field in bitmap supplied as *arg

*/

bool Item_func_set_user_var::register_field_in_bitmap(unsigned char *arg)
{
  MY_BITMAP *bitmap = (MY_BITMAP *) arg;
  assert(bitmap);
  if (result_field)
  {
    bitmap_set_bit(bitmap, result_field->field_index);
  }
  return 0;
}


/**
  Set value to user variable.

  @param entry          pointer to structure representing variable
  @param set_null       should we set NULL value ?
  @param ptr            pointer to buffer with new value
  @param length         length of new value
  @param type           type of new value
  @param cs             charset info for new value
  @param dv             derivation for new value
  @param unsigned_arg   indiates if a value of type INT_RESULT is unsigned

  @note Sets error and fatal error if allocation fails.

  @retval
    false   success
  @retval
    true    failure
*/

#define extra_size sizeof(double)

static bool
update_hash(user_var_entry *entry, bool set_null, void *ptr, uint32_t length,
            Item_result type, const CHARSET_INFO * const cs, Derivation dv,
            bool unsigned_arg)
{
  if (set_null)
  {
    char *pos= (char*) entry+ ALIGN_SIZE(sizeof(user_var_entry));
    if (entry->value && entry->value != pos)
      free(entry->value);
    entry->value= 0;
    entry->length= 0;
  }
  else
  {
    if (type == STRING_RESULT)
      length++;					// Store strings with end \0
    if (length <= extra_size)
    {
      /* Save value in value struct */
      char *pos= (char*) entry+ ALIGN_SIZE(sizeof(user_var_entry));
      if (entry->value != pos)
      {
	if (entry->value)
	  free(entry->value);
	entry->value=pos;
      }
    }
    else
    {
      /* Allocate variable */
      if (entry->length != length)
      {
	char *pos= (char*) entry+ ALIGN_SIZE(sizeof(user_var_entry));
	if (entry->value == pos)
	  entry->value=0;
        entry->value= (char*) my_realloc(entry->value, length,
                                         MYF(MY_ALLOW_ZERO_PTR | MY_WME |
                                             ME_FATALERROR));
        if (!entry->value)
	  return 1;
      }
    }
    if (type == STRING_RESULT)
    {
      length--;					// Fix length change above
      entry->value[length]= 0;			// Store end \0
    }
    memcpy(entry->value,ptr,length);
    if (type == DECIMAL_RESULT)
      ((my_decimal*)entry->value)->fix_buffer_pointer();
    entry->length= length;
    entry->collation.set(cs, dv);
    entry->unsigned_flag= unsigned_arg;
  }
  entry->type=type;
  return 0;
}


bool
Item_func_set_user_var::update_hash(void *ptr, uint32_t length,
                                    Item_result res_type,
                                    const CHARSET_INFO * const cs, Derivation dv,
                                    bool unsigned_arg)
{
  /*
    If we set a variable explicitely to NULL then keep the old
    result type of the variable
  */
  if ((null_value= args[0]->null_value) && null_item)
    res_type= entry->type;                      // Don't change type of item
  if (::update_hash(entry, (null_value= args[0]->null_value),
                    ptr, length, res_type, cs, dv, unsigned_arg))
  {
    null_value= 1;
    return 1;
  }
  return 0;
}


/** Get the value of a variable as a double. */

double user_var_entry::val_real(bool *null_value)
{
  if ((*null_value= (value == 0)))
    return 0.0;

  switch (type) {
  case REAL_RESULT:
    return *(double*) value;
  case INT_RESULT:
    return (double) *(int64_t*) value;
  case DECIMAL_RESULT:
  {
    double result;
    my_decimal2double(E_DEC_FATAL_ERROR, (my_decimal *)value, &result);
    return result;
  }
  case STRING_RESULT:
    return my_atof(value);                      // This is null terminated
  case ROW_RESULT:
    assert(1);				// Impossible
    break;
  }
  return 0.0;					// Impossible
}


/** Get the value of a variable as an integer. */

int64_t user_var_entry::val_int(bool *null_value) const
{
  if ((*null_value= (value == 0)))
    return 0L;

  switch (type) {
  case REAL_RESULT:
    return (int64_t) *(double*) value;
  case INT_RESULT:
    return *(int64_t*) value;
  case DECIMAL_RESULT:
  {
    int64_t result;
    my_decimal2int(E_DEC_FATAL_ERROR, (my_decimal *)value, 0, &result);
    return result;
  }
  case STRING_RESULT:
  {
    int error;
    return my_strtoll10(value, (char**) 0, &error);// String is null terminated
  }
  case ROW_RESULT:
    assert(1);				// Impossible
    break;
  }
  return 0L;					// Impossible
}


/** Get the value of a variable as a string. */

String *user_var_entry::val_str(bool *null_value, String *str,
				uint32_t decimals)
{
  if ((*null_value= (value == 0)))
    return (String*) 0;

  switch (type) {
  case REAL_RESULT:
    str->set_real(*(double*) value, decimals, &my_charset_bin);
    break;
  case INT_RESULT:
    if (!unsigned_flag)
      str->set(*(int64_t*) value, &my_charset_bin);
    else
      str->set(*(uint64_t*) value, &my_charset_bin);
    break;
  case DECIMAL_RESULT:
    my_decimal2string(E_DEC_FATAL_ERROR, (my_decimal *)value, 0, 0, 0, str);
    break;
  case STRING_RESULT:
    if (str->copy(value, length, collation.collation))
      str= 0;					// EOM error
  case ROW_RESULT:
    assert(1);				// Impossible
    break;
  }
  return(str);
}

/** Get the value of a variable as a decimal. */

my_decimal *user_var_entry::val_decimal(bool *null_value, my_decimal *val)
{
  if ((*null_value= (value == 0)))
    return 0;

  switch (type) {
  case REAL_RESULT:
    double2my_decimal(E_DEC_FATAL_ERROR, *(double*) value, val);
    break;
  case INT_RESULT:
    int2my_decimal(E_DEC_FATAL_ERROR, *(int64_t*) value, 0, val);
    break;
  case DECIMAL_RESULT:
    val= (my_decimal *)value;
    break;
  case STRING_RESULT:
    str2my_decimal(E_DEC_FATAL_ERROR, value, length, collation.collation, val);
    break;
  case ROW_RESULT:
    assert(1);				// Impossible
    break;
  }
  return(val);
}

/**
  This functions is invoked on SET \@variable or
  \@variable:= expression.

  Evaluate (and check expression), store results.

  @note
    For now it always return OK. All problem with value evaluating
    will be caught by session->is_error() check in sql_set_variables().

  @retval
    false OK.
*/

bool
Item_func_set_user_var::check(bool use_result_field)
{
  if (use_result_field && !result_field)
    use_result_field= false;

  switch (cached_result_type) {
  case REAL_RESULT:
  {
    save_result.vreal= use_result_field ? result_field->val_real() :
                        args[0]->val_real();
    break;
  }
  case INT_RESULT:
  {
    save_result.vint= use_result_field ? result_field->val_int() :
                       args[0]->val_int();
    unsigned_flag= use_result_field ? ((Field_num*)result_field)->unsigned_flag:
                    args[0]->unsigned_flag;
    break;
  }
  case STRING_RESULT:
  {
    save_result.vstr= use_result_field ? result_field->val_str(&value) :
                       args[0]->val_str(&value);
    break;
  }
  case DECIMAL_RESULT:
  {
    save_result.vdec= use_result_field ?
                       result_field->val_decimal(&decimal_buff) :
                       args[0]->val_decimal(&decimal_buff);
    break;
  }
  case ROW_RESULT:
  default:
    // This case should never be chosen
    assert(0);
    break;
  }
  return(false);
}


/**
  This functions is invoked on
  SET \@variable or \@variable:= expression.

  @note
    We have to store the expression as such in the variable, independent of
    the value method used by the user

  @retval
    0	OK
  @retval
    1	EOM Error

*/

bool
Item_func_set_user_var::update()
{
  bool res= false;

  switch (cached_result_type) {
  case REAL_RESULT:
  {
    res= update_hash((void*) &save_result.vreal,sizeof(save_result.vreal),
		     REAL_RESULT, &my_charset_bin, DERIVATION_IMPLICIT, 0);
    break;
  }
  case INT_RESULT:
  {
    res= update_hash((void*) &save_result.vint, sizeof(save_result.vint),
                     INT_RESULT, &my_charset_bin, DERIVATION_IMPLICIT,
                     unsigned_flag);
    break;
  }
  case STRING_RESULT:
  {
    if (!save_result.vstr)					// Null value
      res= update_hash((void*) 0, 0, STRING_RESULT, &my_charset_bin,
		       DERIVATION_IMPLICIT, 0);
    else
      res= update_hash((void*) save_result.vstr->ptr(),
		       save_result.vstr->length(), STRING_RESULT,
		       save_result.vstr->charset(),
		       DERIVATION_IMPLICIT, 0);
    break;
  }
  case DECIMAL_RESULT:
  {
    if (!save_result.vdec)					// Null value
      res= update_hash((void*) 0, 0, DECIMAL_RESULT, &my_charset_bin,
                       DERIVATION_IMPLICIT, 0);
    else
      res= update_hash((void*) save_result.vdec,
                       sizeof(my_decimal), DECIMAL_RESULT,
                       &my_charset_bin, DERIVATION_IMPLICIT, 0);
    break;
  }
  case ROW_RESULT:
  default:
    // This case should never be chosen
    assert(0);
    break;
  }
  return(res);
}


double Item_func_set_user_var::val_real()
{
  assert(fixed == 1);
  check(0);
  update();					// Store expression
  return entry->val_real(&null_value);
}

int64_t Item_func_set_user_var::val_int()
{
  assert(fixed == 1);
  check(0);
  update();					// Store expression
  return entry->val_int(&null_value);
}

String *Item_func_set_user_var::val_str(String *str)
{
  assert(fixed == 1);
  check(0);
  update();					// Store expression
  return entry->val_str(&null_value, str, decimals);
}


my_decimal *Item_func_set_user_var::val_decimal(my_decimal *val)
{
  assert(fixed == 1);
  check(0);
  update();					// Store expression
  return entry->val_decimal(&null_value, val);
}


double Item_func_set_user_var::val_result()
{
  assert(fixed == 1);
  check(true);
  update();					// Store expression
  return entry->val_real(&null_value);
}

int64_t Item_func_set_user_var::val_int_result()
{
  assert(fixed == 1);
  check(true);
  update();					// Store expression
  return entry->val_int(&null_value);
}

String *Item_func_set_user_var::str_result(String *str)
{
  assert(fixed == 1);
  check(true);
  update();					// Store expression
  return entry->val_str(&null_value, str, decimals);
}


my_decimal *Item_func_set_user_var::val_decimal_result(my_decimal *val)
{
  assert(fixed == 1);
  check(true);
  update();					// Store expression
  return entry->val_decimal(&null_value, val);
}


void Item_func_set_user_var::print(String *str, enum_query_type query_type)
{
  str->append(STRING_WITH_LEN("(@"));
  str->append(name.str, name.length);
  str->append(STRING_WITH_LEN(":="));
  args[0]->print(str, query_type);
  str->append(')');
}


void Item_func_set_user_var::print_as_stmt(String *str,
                                           enum_query_type query_type)
{
  str->append(STRING_WITH_LEN("set @"));
  str->append(name.str, name.length);
  str->append(STRING_WITH_LEN(":="));
  args[0]->print(str, query_type);
  str->append(')');
}

bool Item_func_set_user_var::send(Protocol *protocol, String *str_arg)
{
  if (result_field)
  {
    check(1);
    update();
    return protocol->store(result_field);
  }
  return Item::send(protocol, str_arg);
}

void Item_func_set_user_var::make_field(Send_field *tmp_field)
{
  if (result_field)
  {
    result_field->make_field(tmp_field);
    assert(tmp_field->table_name != 0);
    if (Item::name)
      tmp_field->col_name=Item::name;               // Use user supplied name
  }
  else
    Item::make_field(tmp_field);
}


/*
  Save the value of a user variable into a field

  SYNOPSIS
    save_in_field()
      field           target field to save the value to
      no_conversion   flag indicating whether conversions are allowed

  DESCRIPTION
    Save the function value into a field and update the user variable
    accordingly. If a result field is defined and the target field doesn't
    coincide with it then the value from the result field will be used as
    the new value of the user variable.

    The reason to have this method rather than simply using the result
    field in the val_xxx() methods is that the value from the result field
    not always can be used when the result field is defined.
    Let's consider the following cases:
    1) when filling a tmp table the result field is defined but the value of it
    is undefined because it has to be produced yet. Thus we can't use it.
    2) on execution of an INSERT ... SELECT statement the save_in_field()
    function will be called to fill the data in the new record. If the SELECT
    part uses a tmp table then the result field is defined and should be
    used in order to get the correct result.

    The difference between the SET_USER_VAR function and regular functions
    like CONCAT is that the Item_func objects for the regular functions are
    replaced by Item_field objects after the values of these functions have
    been stored in a tmp table. Yet an object of the Item_field class cannot
    be used to update a user variable.
    Due to this we have to handle the result field in a special way here and
    in the Item_func_set_user_var::send() function.

  RETURN VALUES
    false       Ok
    true        Error
*/

int Item_func_set_user_var::save_in_field(Field *field, bool no_conversions,
                                          bool can_use_result_field)
{
  bool use_result_field= (!can_use_result_field ? 0 :
                          (result_field && result_field != field));
  int error;

  /* Update the value of the user variable */
  check(use_result_field);
  update();

  if (result_type() == STRING_RESULT ||
      (result_type() == REAL_RESULT && field->result_type() == STRING_RESULT))
  {
    String *result;
    const CHARSET_INFO * const cs= collation.collation;
    char buff[MAX_FIELD_WIDTH];		// Alloc buffer for small columns
    str_value.set_quick(buff, sizeof(buff), cs);
    result= entry->val_str(&null_value, &str_value, decimals);

    if (null_value)
    {
      str_value.set_quick(0, 0, cs);
      return set_field_to_null_with_conversions(field, no_conversions);
    }

    /* NOTE: If null_value == false, "result" must be not NULL.  */

    field->set_notnull();
    error=field->store(result->ptr(),result->length(),cs);
    str_value.set_quick(0, 0, cs);
  }
  else if (result_type() == REAL_RESULT)
  {
    double nr= entry->val_real(&null_value);
    if (null_value)
      return set_field_to_null(field);
    field->set_notnull();
    error=field->store(nr);
  }
  else if (result_type() == DECIMAL_RESULT)
  {
    my_decimal decimal_value;
    my_decimal *val= entry->val_decimal(&null_value, &decimal_value);
    if (null_value)
      return set_field_to_null(field);
    field->set_notnull();
    error=field->store_decimal(val);
  }
  else
  {
    int64_t nr= entry->val_int(&null_value);
    if (null_value)
      return set_field_to_null_with_conversions(field, no_conversions);
    field->set_notnull();
    error=field->store(nr, unsigned_flag);
  }
  return error;
}


bool Item_user_var_as_out_param::fix_fields(Session *session, Item **ref)
{
  assert(fixed == 0);
  if (Item::fix_fields(session, ref) ||
      !(entry= get_variable(&session->user_vars, name, 1)))
    return true;
  entry->type= STRING_RESULT;
  /*
    Let us set the same collation which is used for loading
    of fields in LOAD DATA INFILE.
    (Since Item_user_var_as_out_param is used only there).
  */
  entry->collation.set(session->variables.collation_database);
  entry->update_query_id= session->query_id;
  return false;
}


void Item_user_var_as_out_param::set_null_value(const CHARSET_INFO * const cs)
{
  ::update_hash(entry, true, 0, 0, STRING_RESULT, cs,
                DERIVATION_IMPLICIT, 0 /* unsigned_arg */);
}


void Item_user_var_as_out_param::set_value(const char *str, uint32_t length,
                                           const CHARSET_INFO * const cs)
{
  ::update_hash(entry, false, (void*)str, length, STRING_RESULT, cs,
                DERIVATION_IMPLICIT, 0 /* unsigned_arg */);
}


double Item_user_var_as_out_param::val_real()
{
  assert(0);
  return 0.0;
}


int64_t Item_user_var_as_out_param::val_int()
{
  assert(0);
  return 0;
}


String* Item_user_var_as_out_param::val_str(String *str __attribute__((unused)))
{
  assert(0);
  return 0;
}


my_decimal* Item_user_var_as_out_param::val_decimal(my_decimal *decimal_buffer __attribute__((unused)))
{
  assert(0);
  return 0;
}


void Item_user_var_as_out_param::print(String *str,
                                       enum_query_type query_type __attribute__((unused)))
{
  str->append('@');
  str->append(name.str,name.length);
}

/***************************************************************************
  System variables
****************************************************************************/

/**
  Return value of an system variable base[.name] as a constant item.

  @param session			Thread handler
  @param var_type		global / session
  @param name		        Name of base or system variable
  @param component		Component.

  @note
    If component.str = 0 then the variable name is in 'name'

  @return
    - 0  : error
    - #  : constant item
*/