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/* Copyright (C) 2000 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 */
/* Handling of arrays that can grow dynamicly. */
#include "mysys_priv.h"
#include "m_string.h"
/*
Initiate dynamic array
SYNOPSIS
init_dynamic_array()
array Pointer to an array
element_size Size of element
init_alloc Number of initial elements
alloc_increment Increment for adding new elements
DESCRIPTION
init_dynamic_array() initiates array and allocate space for
init_alloc eilements.
Array is usable even if space allocation failed.
RETURN VALUE
TRUE my_malloc_ci() failed
FALSE Ok
*/
my_bool init_dynamic_array(DYNAMIC_ARRAY *array, uint element_size,
uint init_alloc,
uint alloc_increment CALLER_INFO_PROTO)
{
DBUG_ENTER("init_dynamic_array");
if (!alloc_increment)
{
alloc_increment=max((8192-MALLOC_OVERHEAD)/element_size,16);
if (init_alloc > 8 && alloc_increment > init_alloc * 2)
alloc_increment=init_alloc*2;
}
if (!init_alloc)
init_alloc=alloc_increment;
array->elements=0;
array->max_element=init_alloc;
array->alloc_increment=alloc_increment;
array->size_of_element=element_size;
if (!(array->buffer=(char*) my_malloc_ci(element_size*init_alloc,MYF(MY_WME))))
{
array->max_element=0;
DBUG_RETURN(TRUE);
}
DBUG_RETURN(FALSE);
}
/*
Insert element at the end of array. Allocate memory if needed.
SYNOPSIS
insert_dynamic()
array
element
RETURN VALUE
TRUE Insert failed
FALSE Ok
*/
my_bool insert_dynamic(DYNAMIC_ARRAY *array, gptr element)
{
gptr buffer;
if (array->elements == array->max_element)
{ /* Call only when nessesary */
if (!(buffer=alloc_dynamic(array)))
return TRUE;
}
else
{
buffer=array->buffer+(array->elements * array->size_of_element);
array->elements++;
}
memcpy(buffer,element,(size_t) array->size_of_element);
return FALSE;
}
/*
Alloc space for next element(s)
SYNOPSIS
alloc_dynamic()
array
DESCRIPTION
alloc_dynamic() checks if there is empty space for at least
one element if not tries to allocate space for alloc_increment
elements at the end of array.
RETURN VALUE
pointer Pointer to empty space for element
0 Error
*/
byte *alloc_dynamic(DYNAMIC_ARRAY *array)
{
if (array->elements == array->max_element)
{
char *new_ptr;
if (!(new_ptr=(char*) my_realloc(array->buffer,(array->max_element+
array->alloc_increment)*
array->size_of_element,
MYF(MY_WME | MY_ALLOW_ZERO_PTR))))
return 0;
array->buffer=new_ptr;
array->max_element+=array->alloc_increment;
}
return array->buffer+(array->elements++ * array->size_of_element);
}
/*
Pop last element from array.
SYNOPSIS
pop_dynamic()
array
RETURN VALUE
pointer Ok
0 Array is empty
*/
byte *pop_dynamic(DYNAMIC_ARRAY *array)
{
if (array->elements)
return array->buffer+(--array->elements * array->size_of_element);
return 0;
}
/*
Replace elemnent in array with given element and index
SYNOPSIS
set_dynamic()
array
element Element to be inserted
idx Index where element is to be inserted
DESCRIPTION
set_dynamic() replaces element in array.
If idx > max_element insert new element. Allocate memory if needed.
RETURN VALUE
TRUE Idx was out of range and allocation of new memory failed
FALSE Ok
*/
my_bool set_dynamic(DYNAMIC_ARRAY *array, gptr element, uint idx)
{
if (idx >= array->elements)
{
if (idx >= array->max_element)
{
uint size;
char *new_ptr;
size=(idx+array->alloc_increment)/array->alloc_increment;
size*= array->alloc_increment;
if (!(new_ptr=(char*) my_realloc(array->buffer,size*
array->size_of_element,
MYF(MY_WME | MY_ALLOW_ZERO_PTR))))
return TRUE;
array->buffer=new_ptr;
array->max_element=size;
}
bzero((gptr) (array->buffer+array->elements*array->size_of_element),
(idx - array->elements)*array->size_of_element);
array->elements=idx+1;
}
memcpy(array->buffer+(idx * array->size_of_element),element,
(size_t) array->size_of_element);
return FALSE;
}
/*
Get an element from array by given index
SYNOPSIS
get_dynamic()
array
gptr Element to be returned. If idx > elements contain zeroes.
idx Index of element wanted.
*/
void get_dynamic(DYNAMIC_ARRAY *array, gptr element, uint idx)
{
if (idx >= array->elements)
{
DBUG_PRINT("warning",("To big array idx: %d, array size is %d",
idx,array->elements));
bzero(element,array->size_of_element);
return;
}
memcpy(element,array->buffer+idx*array->size_of_element,
(size_t) array->size_of_element);
}
/*
Empty array by freeing all memory
SYNOPSIS
delete_dynamic()
array Array to be deleted
*/
void delete_dynamic(DYNAMIC_ARRAY *array)
{
if (array->buffer)
{
my_free(array->buffer,MYF(MY_WME));
array->buffer=0;
array->elements=array->max_element=0;
}
}
/*
Delete element by given index
SYNOPSIS
delete_dynamic_element()
array
idx Index of element to be deleted
*/
void delete_dynamic_element(DYNAMIC_ARRAY *array, uint idx)
{
char *ptr=array->buffer+array->size_of_element*idx;
array->elements--;
memmove(ptr,ptr+array->size_of_element,
(array->elements-idx)*array->size_of_element);
}
/*
Free unused memory
SYNOPSIS
freeze_size()
array Array to be freed
*/
void freeze_size(DYNAMIC_ARRAY *array)
{
uint elements=max(array->elements,1);
if (array->buffer && array->max_element != elements)
{
array->buffer=(char*) my_realloc(array->buffer,
elements*array->size_of_element,
MYF(MY_WME));
array->max_element=elements;
}
}
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