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st.c
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st.c
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/**
@file
@ingroup st
@brief Symbol table package.
@details The st library provides functions to create, maintain,
and query symbol tables.
@copyright@parblock
Copyright (c) 1994-1998 The Regents of the Univ. of California.
All rights reserved.
Permission is hereby granted, without written agreement and without license
or royalty fees, to use, copy, modify, and distribute this software and its
documentation for any purpose, provided that the above copyright notice and
the following two paragraphs appear in all copies of this software.
IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN
"AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO PROVIDE
MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
@endparblock
@copyright@parblock
Copyright (c) 1999-2015, Regents of the University of Colorado
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
Neither the name of the University of Colorado nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
@endparblock
*/
#include "util.h"
#include "st.h"
/*---------------------------------------------------------------------------*/
/* Constant declarations */
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
/* Type declarations */
/*---------------------------------------------------------------------------*/
/**
* @brief Type of symbol table entries.
*/
typedef struct st_table_entry st_table_entry;
/*---------------------------------------------------------------------------*/
/* Stucture declarations */
/*---------------------------------------------------------------------------*/
/**
* @brief Symbol table entry.
*/
struct st_table_entry {
void *key;
void *record;
st_table_entry *next;
};
/**
* @brief Symbol table header.
*/
struct st_table {
st_compare_t compare;
st_hash_t hash;
st_compare_arg_t compare_arg;
st_hash_arg_t hash_arg;
void const * arg;
int num_bins;
int num_entries;
int max_density;
int reorder_flag;
double grow_factor;
st_table_entry **bins;
};
/**
* @brief Symbol table generator.
*/
struct st_generator {
st_table const *table;
st_table_entry const *entry;
int index;
};
/*---------------------------------------------------------------------------*/
/* Variable declarations */
/*---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
/* Macro declarations */
/*---------------------------------------------------------------------------*/
/**
* @brief Compares two numbers or two pointers.
*
* @details Used by the default comparison functions.
*/
#define ST_NUMCMP(x,y) ((x) != (y))
/**
* @brief Hash function for numbers.
*/
#define ST_NUMHASH(x,size) ((int)((uintptr_t)(x)%(uintptr_t)(size)))
/**
* @brief Amount by which pointers should be shifted right when hashing.
*
* @details This is to discard bits that are (likely to be) 0 due to
* alignment constraints.
*/
#if SIZEOF_VOID_P == 8
#define st_shift 3
#else
#define st_shift 2
#endif
/**
* @brief Hash function for pointers.
*/
#define ST_PTRHASH(x,size) ((int)(((uintptr_t)(x)>>st_shift)%(uintptr_t)(size)))
/**
* @brief Compares two entries.
*/
#define EQUAL(table, x, y) \
((((table)->compare == st_numcmp) || ((table)->compare == st_ptrcmp)) ?\
(ST_NUMCMP((x),(y)) == 0) : ((table)->compare) ?\
((*(table)->compare)((x), (y)) == 0) :\
((*(table)->compare_arg)((x), (y), (table)->arg) == 0))
/**
* @brief Computes the hash of one entry.
*/
#define do_hash(key, table)\
(((table)->hash == st_ptrhash) ? ST_PTRHASH((key), (table)->num_bins) : \
((table)->hash == st_numhash) ? ST_NUMHASH((key), (table)->num_bins) : \
((table)->hash) ? (*(table)->hash)((key), (table)->num_bins) : \
(*(table)->hash_arg)((key), (table)->num_bins, (table)->arg))
/**
* @brief Compares the new key to one in a collision list.
*/
#define PTR_NOT_EQUAL(table, ptr, user_key)\
((ptr) != NIL(st_table_entry) && \
!EQUAL((table), (user_key), (ptr)->key))
/**
* @brief Looks up an entry in a collision list.
*
* @details If the entry is found and the reorder flag is set, the found
* entry is brought to the fore of the collision list.
*/
#define FIND_ENTRY(table, hash_val, key, ptr, last) \
(last) = &(table)->bins[hash_val];\
(ptr) = *(last);\
while (PTR_NOT_EQUAL((table), (ptr), (key))) {\
(last) = &(ptr)->next; (ptr) = *(last);\
}\
if ((ptr) != NIL(st_table_entry) && (table)->reorder_flag) {\
*(last) = (ptr)->next;\
(ptr)->next = (table)->bins[hash_val];\
(table)->bins[hash_val] = (ptr);\
}
/**
* @brief Adds an entry to a table.
*
* @deprecated This macro does not check if memory allocation fails.
* Use at your own risk.
*/
#define ADD_DIRECT(table, key, value, hash_val, newt)\
{\
if (table->num_entries/table->num_bins >= table->max_density) {\
rehash(table);\
hash_val = do_hash(key,table);\
}\
\
newt = ALLOC(st_table_entry, 1);\
\
newt->key = key;\
newt->record = value;\
newt->next = table->bins[hash_val];\
table->bins[hash_val] = newt;\
table->num_entries++;\
}
/** \cond */
/*---------------------------------------------------------------------------*/
/* Static function prototypes */
/*---------------------------------------------------------------------------*/
static int rehash (st_table *);
/** \endcond */
/*---------------------------------------------------------------------------*/
/* Definition of exported functions */
/*---------------------------------------------------------------------------*/
/**
@brief Creates and initializes a table.
@details Creates and initializes a table with the comparison function
compare_fn and hash function hash_fn. compare_fn is
int compare_fn(const void *key1, const void *key2)
It returns `<,=,> 0` depending on whether `key1 <,=,> key2` by some
measure.<p>
hash_fn is
int hash_fn(void *key, int modulus)
It returns an integer between `0` and `modulus-1` such that if
`compare_fn(key1,key2) == 0` then `hash_fn(key1) == hash_fn(key2)`.<p>
There are five predefined hash and comparison functions in st.
For keys as numbers:
st_numhash(key, modulus) { return (unsigned int) key % modulus; }
st_numcmp(x,y) { return (int) x - (int) y; }
For keys as pointers:
st_ptrhash(key, modulus) { return ((unsigned int) key/4) % modulus }
st_ptrcmp(x,y) { return (int) x - (int) y; }
For keys as strings:
st_strhash(x,y) - a reasonable hashing function for strings
strcmp(x,y) - the standard library function
It is recommended to use these particular functions if they fit your
needs, since st will recognize certain of them and run more quickly
because of it.
@sideeffect None
@see st_init_table_with_params st_free_table
*/
st_table *
st_init_table(st_compare_t compare, st_hash_t hash)
{
return st_init_table_with_params(compare, hash, ST_DEFAULT_INIT_TABLE_SIZE,
ST_DEFAULT_MAX_DENSITY,
ST_DEFAULT_GROW_FACTOR,
ST_DEFAULT_REORDER_FLAG);
} /* st_init_table */
/**
@brief Create a table with given parameters.
@details The full blown table initializer. compare and hash are
the same as in st_init_table. density is the largest the average
number of entries per hash bin there should be before the table is
grown. grow_factor is the factor the table is grown by when it
becomes too full. size is the initial number of bins to be allocated
for the hash table. If reorder_flag is non-zero, then every time an
entry is found, it is moved to the top of the chain.<p>
st_init_table(compare, hash) is equivelent to
st_init_table_with_params(compare, hash, ST_DEFAULT_INIT_TABLE_SIZE,
ST_DEFAULT_MAX_DENSITY, ST_DEFAULT_GROW_FACTOR,
ST_DEFAULT_REORDER_FLAG);
@sideeffect None
@see st_init_table st_free_table
*/
st_table *
st_init_table_with_params(
st_compare_t compare,
st_hash_t hash,
int size,
int density,
double grow_factor,
int reorder_flag)
{
int i;
st_table *newt;
newt = ALLOC(st_table, 1);
if (newt == NIL(st_table)) {
return NIL(st_table);
}
newt->compare = compare;
newt->hash = hash;
newt->compare_arg = (st_compare_arg_t) 0;
newt->hash_arg = (st_hash_arg_t) 0;
newt->arg = NIL(void);
newt->num_entries = 0;
newt->max_density = density;
newt->grow_factor = grow_factor;
newt->reorder_flag = reorder_flag;
if (size <= 0) {
size = 1;
}
newt->num_bins = size;
newt->bins = ALLOC(st_table_entry *, size);
if (newt->bins == NIL(st_table_entry *)) {
FREE(newt);
return NIL(st_table);
}
for(i = 0; i < size; i++) {
newt->bins[i] = 0;
}
return newt;
} /* st_init_table_with_params */
/**
@brief Creates and initializes a table.
@details Like st_init_table_with_params, but the comparison and
hash functions are passed an extra parameter `arg` that is
registered in the table at initialization.
@see st_init_table_with_params
*/
st_table *
st_init_table_with_params_and_arg(
st_compare_arg_t compare,
st_hash_arg_t hash,
void const * arg,
int size,
int density,
double growth_factor,
int reorder_flag)
{
st_table *table;
table = st_init_table_with_params((st_compare_t) 0, (st_hash_t) 0, size,
density, growth_factor, reorder_flag);
if (table == NIL(st_table))
return NIL(st_table);
table->compare_arg = compare;
table->hash_arg = hash;
table->arg = arg;
return table;
} /* st_init_table_with_params_and_arg */
/**
@brief Creates and initializes a table.
@details Like st_init_table, but the comparison and hash functions are
passed an extra parameter `arg` that is registered in the table at
initialization.
@see st_init_table st_init_table_with_params_and_arg
*/
st_table *
st_init_table_with_arg(
st_compare_arg_t compare,
st_hash_arg_t hash,
void const * arg)
{
return st_init_table_with_params_and_arg(compare, hash, arg,
ST_DEFAULT_INIT_TABLE_SIZE,
ST_DEFAULT_MAX_DENSITY,
ST_DEFAULT_GROW_FACTOR,
ST_DEFAULT_REORDER_FLAG);
} /* st_init_table_with_arg */
/**
@brief Free a table.
@details Any internal storage associated with table is freed. It is
the user's responsibility to free any storage associated with the
pointers he placed in the table (by perhaps using st_foreach).
@sideeffect None
@see st_init_table st_init_table_with_params
*/
void
st_free_table(st_table *table)
{
st_table_entry *ptr, *next;
int i;
for(i = 0; i < table->num_bins ; i++) {
ptr = table->bins[i];
while (ptr != NIL(st_table_entry)) {
next = ptr->next;
FREE(ptr);
ptr = next;
}
}
FREE(table->bins);
FREE(table);
} /* st_free_table */
/**
@brief Lookup up `key` in `table`.
@details If an entry is found, 1 is returned and if `value` is not
nil, the variable it points to is set to the associated value. If
an entry is not found, 0 is returned and the variable pointed by
value is unchanged.
@sideeffect The location pointed by value is modified.
@see st_lookup_int
*/
int
st_lookup(st_table *table, void const *key, void **value)
{
int hash_val;
st_table_entry *ptr, **last;
hash_val = do_hash(key, table);
FIND_ENTRY(table, hash_val, key, ptr, last);
if (ptr == NIL(st_table_entry)) {
return 0;
} else {
if (value != NIL(void *)) {
*value = ptr->record;
}
return 1;
}
} /* st_lookup */
/**
@brief Lookup up `key` in `table`.
@details If an entry is found, 1 is returned and if `value` is not
nil, the variable it points to is set to the associated integer
value. If an entry is not found, 0 is return and the variable
pointed by `value` is unchanged.
@sideeffect The location pointed by value is modified.
@see st_lookup
*/
int
st_lookup_int(st_table *table, void const *key, int *value)
{
int hash_val;
st_table_entry *ptr, **last;
hash_val = do_hash(key, table);
FIND_ENTRY(table, hash_val, key, ptr, last);
if (ptr == NIL(st_table_entry)) {
return 0;
} else {
if (value != NIL(int)) {
*value = (int) (intptr_t) ptr->record;
}
return 1;
}
} /* st_lookup_int */
/**
@brief Insert value in `table` under the key `key`.
@return 1 if there was an entry already under the key; 0 if there
was no entry under the key and insertion was successful;
ST_OUT_OF_MEM otherwise. In either of the first two cases the new
value is added.
@sideeffect None
*/
int
st_insert(st_table *table, void *key, void *value)
{
int hash_val;
st_table_entry *newt;
st_table_entry *ptr, **last;
hash_val = do_hash(key, table);
FIND_ENTRY(table, hash_val, key, ptr, last);
if (ptr == NIL(st_table_entry)) {
if (table->num_entries/table->num_bins >= table->max_density) {
if (rehash(table) == ST_OUT_OF_MEM) {
return ST_OUT_OF_MEM;
}
hash_val = do_hash(key, table);
}
newt = ALLOC(st_table_entry, 1);
if (newt == NIL(st_table_entry)) {
return ST_OUT_OF_MEM;
}
newt->key = key;
newt->record = value;
newt->next = table->bins[hash_val];
table->bins[hash_val] = newt;
table->num_entries++;
return 0;
} else {
ptr->record = value;
return 1;
}
} /* st_insert */
/**
@brief Place 'value' in 'table' under the key 'key'.
@details This is done without checking if 'key' is in 'table'
already. This should only be used if you are sure there is not
already an entry for 'key', since it is undefined which entry you
would later get from st_lookup or st_find_or_add.
@return 1 if successful; ST_OUT_OF_MEM otherwise.
@sideeffect None
@see st_lookup st_find_or_add
*/
int
st_add_direct(st_table *table, void *key, void *value)
{
int hash_val;
st_table_entry *newt;
if (table->num_entries / table->num_bins >= table->max_density) {
if (rehash(table) == ST_OUT_OF_MEM) {
return ST_OUT_OF_MEM;
}
}
hash_val = do_hash(key, table);
newt = ALLOC(st_table_entry, 1);
if (newt == NIL(st_table_entry)) {
return ST_OUT_OF_MEM;
}
newt->key = key;
newt->record = value;
newt->next = table->bins[hash_val];
table->bins[hash_val] = newt;
table->num_entries++;
return 1;
} /* st_add_direct */
/**
@brief Lookup `key` in `table`; if not found, create an entry.
@details In either case set slot to point to the field in the entry
where the value is stored. The value associated with `key` may then
be changed by accessing directly through slot. As an example:
void **slot;
void *key;
void *value = item_ptr // ptr to a malloc'd structure
if (st_find_or_add(table, key, &slot) == 1) {
FREE(*slot); // free the old value of the record
}
*slot = value; // attach the new value to the record
This replaces the equivelent code:
if (st_lookup(table, key, &ovalue) == 1) {
FREE(ovalue);
}
st_insert(table, key, value);
@return 1 if an entry already existed, 0 if it did not exist and
creation was successful; ST_OUT_OF_MEM otherwise.
@sideeffect The location pointed by slot is modified.
@see st_find
*/
int
st_find_or_add(st_table *table, void *key, void ***slot)
{
int hash_val;
st_table_entry *newt, *ptr, **last;
hash_val = do_hash(key, table);
FIND_ENTRY(table, hash_val, key, ptr, last);
if (ptr == NIL(st_table_entry)) {
if (table->num_entries / table->num_bins >= table->max_density) {
if (rehash(table) == ST_OUT_OF_MEM) {
return ST_OUT_OF_MEM;
}
hash_val = do_hash(key, table);
}
newt = ALLOC(st_table_entry, 1);
if (newt == NIL(st_table_entry)) {
return ST_OUT_OF_MEM;
}
newt->key = key;
newt->record = NIL(void);
newt->next = table->bins[hash_val];
table->bins[hash_val] = newt;
table->num_entries++;
if (slot != NIL(void **)) *slot = &newt->record;
return 0;
} else {
if (slot != NIL(void **)) *slot = &ptr->record;
return 1;
}
} /* st_find_or_add */
/**
@brief Lookup `key` in `table`.
@details Like st_find_or_add, but does not create an entry if one is
not found.
@sideeffect The location pointed by slot is modified.
@see st_find_or_add
*/
int
st_find(st_table *table, void const *key, void ***slot)
{
int hash_val;
st_table_entry *ptr, **last;
hash_val = do_hash(key, table);
FIND_ENTRY(table, hash_val, key, ptr, last);
if (ptr == NIL(st_table_entry)) {
return 0;
} else {
if (slot != NIL(void **)) {
*slot = &ptr->record;
}
return 1;
}
} /* st_find */
/**
@brief Returns a copy of old_table and all its members.
@details (st_table *) 0 is returned if there was insufficient memory
to do the copy.
@sideeffect None
*/
st_table *
st_copy
(st_table const *old_table)
{
st_table *new_table;
st_table_entry *ptr, *newptr, *next, *newt;
int i, j, num_bins = old_table->num_bins;
new_table = ALLOC(st_table, 1);
if (new_table == NIL(st_table)) {
return NIL(st_table);
}
*new_table = *old_table;
new_table->bins = ALLOC(st_table_entry *, num_bins);
if (new_table->bins == NIL(st_table_entry *)) {
FREE(new_table);
return NIL(st_table);
}
for(i = 0; i < num_bins ; i++) {
new_table->bins[i] = NIL(st_table_entry);
ptr = old_table->bins[i];
while (ptr != NIL(st_table_entry)) {
newt = ALLOC(st_table_entry, 1);
if (newt == NIL(st_table_entry)) {
for (j = 0; j <= i; j++) {
newptr = new_table->bins[j];
while (newptr != NIL(st_table_entry)) {
next = newptr->next;
FREE(newptr);
newptr = next;
}
}
FREE(new_table->bins);
FREE(new_table);
return NIL(st_table);
}
*newt = *ptr;
newt->next = new_table->bins[i];
new_table->bins[i] = newt;
ptr = ptr->next;
}
}
return new_table;
} /* st_copy */
/**
@brief Deletes the entry with the key pointed to by `keyp`.
@details If the entry is found, 1 is returned, the variable pointed
by `keyp` is set to the actual key and the variable pointed by
`value` is set to the corresponding entry. (This allows the freeing
of the associated storage.) If the entry is not found, then 0 is
returned and nothing is changed.
@sideeffect The locations pointed by keyp and value are modified.
@see st_delete_int
*/
int
st_delete(st_table *table, void **keyp, void **value)
{
int hash_val;
void *key = *keyp;
st_table_entry *ptr, **last;
hash_val = do_hash(key, table);
FIND_ENTRY(table, hash_val, key, ptr ,last);
if (ptr == NIL(st_table_entry)) {
return 0;
}
*last = ptr->next;
if (value != NIL(void *)) *value = ptr->record;
*keyp = ptr->key;
FREE(ptr);
table->num_entries--;
return 1;
} /* st_delete */
/**
@brief Deletes the entry with the key pointed to by `keyp`.
@details `value` must be a pointer to an integer. If the entry is
found, 1 is returned, the variable pointed by `keyp` is set to the
actual key and the variable pointed by `value` is set to the
corresponding entry. (This allows the freeing of the associated
storage.) If the entry is not found, then 0 is returned and nothing
is changed.
@sideeffect The locations pointed by keyp and value are modified.
@see st_delete
*/
int
st_delete_int(st_table *table, void **keyp, int *value)
{
int hash_val;
void *key = *keyp;
st_table_entry *ptr, **last;
hash_val = do_hash(key, table);
FIND_ENTRY(table, hash_val, key, ptr ,last);
if (ptr == NIL(st_table_entry)) {
return 0;
}
*last = ptr->next;
if (value != NIL(int)) *value = (int) (intptr_t) ptr->record;
*keyp = ptr->key;
FREE(ptr);
table->num_entries--;
return 1;
} /* st_delete_int */
/**
@brief Returns the number of entries in the table `table`.
@sideeffect None
*/
int st_count(st_table const *table)
{
return table->num_entries;
}
/**
@brief Iterates over the elements of a table.
@details
For each (key, value) record in `table`, st_foreach
calls func with the arguments
(*func)(key, value, arg)
If func returns ST_CONTINUE, st_foreach continues
processing entries. If func returns ST_STOP, st_foreach stops
processing and returns immediately. If func returns ST_DELETE, then
the entry is deleted from the symbol table and st_foreach continues.
In the case of ST_DELETE, it is func's responsibility to free the
key and value, if necessary. The order in which the records are
visited will be seemingly random.
@return 1 if all items in the table were generated and 0 if the
generation sequence was aborted using ST_STOP.
@sideeffect None
@see st_foreach_item st_foreach_item_int
*/
int
st_foreach(st_table *table, st_foreach_t func, void *arg)
{
st_table_entry *ptr, **last;
enum st_retval retval;
int i;
for(i = 0; i < table->num_bins; i++) {
last = &table->bins[i]; ptr = *last;
while (ptr != NIL(st_table_entry)) {
retval = (*func)(ptr->key, ptr->record, arg);
switch (retval) {
case ST_CONTINUE:
last = &ptr->next; ptr = *last;
break;
case ST_STOP:
return 0;
case ST_DELETE:
*last = ptr->next;
table->num_entries--; /* cstevens@ic */
FREE(ptr);
ptr = *last;
}
}
}
return 1;
} /* st_foreach */
/**
@brief String hash function.
@sideeffect None
@see st_init_table
*/
int
st_strhash(void const *string, int modulus)
{
int val = 0;
int c;
char const * s = (char const *) string;
while ((c = *s++) != '\0') {
val = val*997 + c;
}
return ((val < 0) ? -val : val)%modulus;
} /* st_strhash */
/**
@brief Integral number hash function.
@sideeffect None
@see st_init_table st_numcmp
*/
int
st_numhash(void const *x, int size)
{
return ST_NUMHASH(x, size);
} /* st_numhash */
/**
@brief Pointer hash function.
@sideeffect None
@see st_init_table st_ptrcmp
*/
int
st_ptrhash(void const *x, int size)
{
return ST_PTRHASH(x, size);
} /* st_ptrhash */
/**
@brief Integral number comparison function.
@sideeffect None
@see st_init_table st_numhash
*/
int
st_numcmp(void const *x, void const *y)
{
return ST_NUMCMP(x, y);
} /* st_numcmp */
/**
@brief Pointer comparison function.
@sideeffect None
@see st_init_table st_ptrhash
*/
int
st_ptrcmp(void const *x, void const *y)
{
return ST_NUMCMP(x, y);
} /* st_ptrcmp */
/**
@brief Initializes a generator.
@details Returns a generator handle which when used with
st_gen() will progressively return each (key, value) record in
`table`.