int compare_fn(const char *key1, const char *key2)It returns <,=,> 0 depending on whether key1 <,=,> key2 by some measure.
hash_fn is
int hash_fn(char *key, int modulus)It returns a integer between 0 and modulus-1 such that if compare_fn(key1,key2) == 0 then hash_fn(key1) == hash_fn(key2).
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 functionIt 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.] SideEffects [None] SeeAlso [st_init_table_with_params st_free_table] ******************************************************************************/ st_table * st_init_table(ST_PFICPCP compare, ST_PFICPI 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 */ /**Function******************************************************************** Synopsis [Create a table with given parameters.] Description [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.
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);] SideEffects [None] SeeAlso [st_init_table st_free_table] ******************************************************************************/ st_table * st_init_table_with_params( ST_PFICPCP compare, ST_PFICPI 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->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 */ /**Function******************************************************************** Synopsis [Free a table.] Description [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).] SideEffects [None] SeeAlso [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 */ /**Function******************************************************************** Synopsis [Lookup up `key' in `table'.] Description [Lookup up `key' in `table'. 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.] SideEffects [None] SeeAlso [st_lookup_int] ******************************************************************************/ int st_lookup(st_table *table, void *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)) { *(char **)value = ptr->record; } return 1; } } /* st_lookup */ /**Function******************************************************************** Synopsis [Lookup up `key' in `table'.] Description [Lookup up `key' in `table'. 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.] SideEffects [None] SeeAlso [st_lookup] ******************************************************************************/ int st_lookup_int(st_table *table, void *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) (long) ptr->record; } return 1; } } /* st_lookup_int */ /**Function******************************************************************** Synopsis [Insert value in table under the key 'key'.] Description [Insert value in table under the key 'key'. Returns 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.] SideEffects [None] SeeAlso [] ******************************************************************************/ 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 = (char *)key; newt->record = (char *)value; newt->next = table->bins[hash_val]; table->bins[hash_val] = newt; table->num_entries++; return 0; } else { ptr->record = (char *)value; return 1; } } /* st_insert */ /**Function******************************************************************** Synopsis [Place 'value' in 'table' under the key 'key'.] Description [Place 'value' in 'table' under the key 'key'. 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. Returns 1 if successful; ST_OUT_OF_MEM otherwise.] SideEffects [None] SeeAlso [] ******************************************************************************/ int st_add_direct(st_table *table, void *key, void *value) { int hash_val; st_table_entry *newt; hash_val = do_hash(key, table); 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 = (char *)key; newt->record = (char *)value; newt->next = table->bins[hash_val]; table->bins[hash_val] = newt; table->num_entries++; return 1; } /* st_add_direct */ /**Function******************************************************************** Synopsis [Lookup `key' in `table'.] Description [Lookup `key' in `table'. If not found, create an entry. 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. Returns 1 if an entry already existed, 0 if it did not exist and creation was successful; ST_OUT_OF_MEM otherwise. As an example:
char **slot;
char *key;
char *value = (char *) 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);
]
SideEffects [None]
SeeAlso [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 = (char *)key;
newt->record = (char *) 0;
newt->next = table->bins[hash_val];
table->bins[hash_val] = newt;
table->num_entries++;
if (slot != NIL(void)) *(char ***)slot = &newt->record;
return 0;
} else {
if (slot != NIL(void)) *(char ***)slot = &ptr->record;
return 1;
}
} /* st_find_or_add */
/**Function********************************************************************
Synopsis [Lookup `key' in `table'.]
Description [Like st_find_or_add, but does not create an entry if
one is not found.]
SideEffects [None]
SeeAlso [st_find_or_add]
******************************************************************************/
int
st_find(st_table *table, void *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)) {
*(char ***)slot = &ptr->record;
}
return 1;
}
} /* st_find */
/**Function********************************************************************
Synopsis [Return a copy of old_table and all its members.]
Description [Return a copy of old_table and all its members.
(st_table *) 0 is returned if there was insufficient memory to do
the copy.]
SideEffects [None]
SeeAlso []
******************************************************************************/
st_table *
st_copy(st_table *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 */
/**Function********************************************************************
Synopsis [Delete the entry with the key pointed to by `keyp'.]
Description [Delete the entry with the key pointed to by `keyp'. 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.]
SideEffects [None]
SeeAlso [st_delete_int]
******************************************************************************/
int
st_delete(st_table *table, void *keyp, void *value)
{
int hash_val;
char *key = *(char **)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)) *(char **)value = ptr->record;
*(char **)keyp = ptr->key;
FREE(ptr);
table->num_entries--;
return 1;
} /* st_delete */
/**Function********************************************************************
Synopsis [Delete the entry with the key pointed to by `keyp'.]
Description [Delete the entry with the key pointed to by `keyp'.
`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.]
SideEffects [None]
SeeAlso [st_delete]
******************************************************************************/
int
st_delete_int(st_table *table, void *keyp, int *value)
{
int hash_val;
char *key = *(char **)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) (long) ptr->record;
*(char **)keyp = ptr->key;
FREE(ptr);
table->num_entries--;
return 1;
} /* st_delete_int */
/**Function********************************************************************
Synopsis [Iterates over the elements of a table.]
Description [For each (key, value) record in `table', st_foreach
call 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 routine returns 1 if all items in the table were generated and 0 if the generation sequence was aborted using ST_STOP. The order in which the records are visited will be seemingly random.] SideEffects [None] SeeAlso [st_foreach_item st_foreach_item_int] ******************************************************************************/ int st_foreach(st_table *table, ST_PFSR func, char *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 */ /**Function******************************************************************** Synopsis [String hash function.] Description [String hash function.] SideEffects [None] SeeAlso [st_init_table] ******************************************************************************/ int st_strhash(char *string, int modulus) { int val = 0; int c; while ((c = *string++) != '\0') { val = val*997 + c; } return ((val < 0) ? -val : val)%modulus; } /* st_strhash */ /**Function******************************************************************** Synopsis [Number hash function.] Description [Integer number hash function.] SideEffects [None] SeeAlso [st_init_table st_numcmp] ******************************************************************************/ int st_numhash(char *x, int size) { return ST_NUMHASH(x, size); } /* st_numhash */ /**Function******************************************************************** Synopsis [Pointer hash function.] Description [Pointer hash function.] SideEffects [None] SeeAlso [st_init_table st_ptrcmp] ******************************************************************************/ int st_ptrhash(char *x, int size) { return ST_PTRHASH(x, size); } /* st_ptrhash */ /**Function******************************************************************** Synopsis [Number comparison function.] Description [integer number comparison function.] SideEffects [None] SeeAlso [st_init_table st_numhash] ******************************************************************************/ int st_numcmp(const char *x, const char *y) { return ST_NUMCMP(x, y); } /* st_numcmp */ /**Function******************************************************************** Synopsis [Pointer comparison function.] Description [Pointer comparison function.] SideEffects [None] SeeAlso [st_init_table st_ptrhash] ******************************************************************************/ int st_ptrcmp(const char *x, const char *y) { return ST_NUMCMP(x, y); } /* st_ptrcmp */ /**Function******************************************************************** Synopsis [Initializes a generator.] Description [Returns a generator handle which when used with st_gen() will progressively return each (key, value) record in `table'.] SideEffects [None] SeeAlso [st_free_gen] ******************************************************************************/ st_generator * st_init_gen(st_table *table) { st_generator *gen; gen = ALLOC(st_generator, 1); if (gen == NIL(st_generator)) { return NIL(st_generator); } gen->table = table; gen->entry = NIL(st_table_entry); gen->index = 0; return gen; } /* st_init_gen */ /**Function******************************************************************** Synopsis [returns the next (key, value) pair in the generation sequence. ] Description [Given a generator returned by st_init_gen(), this routine returns the next (key, value) pair in the generation sequence. The pointer `value_p' can be zero which means no value will be returned. When there are no more items in the generation sequence, the routine returns 0. While using a generation sequence, deleting any (key, value) pair other than the one just generated may cause a fatal error when st_gen() is called later in the sequence and is therefore not recommended.] SideEffects [None] SeeAlso [st_gen_int] ******************************************************************************/ int st_gen(st_generator *gen, void *key_p, void *value_p) { int i; if (gen->entry == NIL(st_table_entry)) { /* try to find next entry */ for(i = gen->index; i < gen->table->num_bins; i++) { if (gen->table->bins[i] != NIL(st_table_entry)) { gen->index = i+1; gen->entry = gen->table->bins[i]; break; } } if (gen->entry == NIL(st_table_entry)) { return 0; /* that's all folks ! */ } } *(char **)key_p = gen->entry->key; if (value_p != NIL(void)) { *(char **)value_p = gen->entry->record; } gen->entry = gen->entry->next; return 1; } /* st_gen */ /**Function******************************************************************** Synopsis [Returns the next (key, value) pair in the generation sequence.] Description [Given a generator returned by st_init_gen(), this routine returns the next (key, value) pair in the generation sequence. `value_p' must be a pointer to an integer. The pointer `value_p' can be zero which means no value will be returned. When there are no more items in the generation sequence, the routine returns 0.] SideEffects [None] SeeAlso [st_gen] ******************************************************************************/ int st_gen_int(st_generator *gen, void *key_p, int *value_p) { int i; if (gen->entry == NIL(st_table_entry)) { /* try to find next entry */ for(i = gen->index; i < gen->table->num_bins; i++) { if (gen->table->bins[i] != NIL(st_table_entry)) { gen->index = i+1; gen->entry = gen->table->bins[i]; break; } } if (gen->entry == NIL(st_table_entry)) { return 0; /* that's all folks ! */ } } *(char **)key_p = gen->entry->key; if (value_p != NIL(int)) { *value_p = (int) (long) gen->entry->record; } gen->entry = gen->entry->next; return 1; } /* st_gen_int */ /**Function******************************************************************** Synopsis [Reclaims the resources associated with `gen'.] Description [After generating all items in a generation sequence, this routine must be called to reclaim the resources associated with `gen'.] SideEffects [None] SeeAlso [st_init_gen] ******************************************************************************/ void st_free_gen(st_generator *gen) { FREE(gen); } /* st_free_gen */ /*---------------------------------------------------------------------------*/ /* Definition of internal functions */ /*---------------------------------------------------------------------------*/ /*---------------------------------------------------------------------------*/ /* Definition of static functions */ /*---------------------------------------------------------------------------*/ /**Function******************************************************************** Synopsis [Rehashes a symbol table.] Description [Rehashes a symbol table.] SideEffects [None] SeeAlso [st_insert] ******************************************************************************/ static int rehash(st_table *table) { st_table_entry *ptr, *next, **old_bins; int i, old_num_bins, hash_val, old_num_entries; /* save old values */ old_bins = table->bins; old_num_bins = table->num_bins; old_num_entries = table->num_entries; /* rehash */ table->num_bins = (int) (table->grow_factor * old_num_bins); if (table->num_bins % 2 == 0) { table->num_bins += 1; } table->num_entries = 0; table->bins = ALLOC(st_table_entry *, table->num_bins); if (table->bins == NIL(st_table_entry *)) { table->bins = old_bins; table->num_bins = old_num_bins; table->num_entries = old_num_entries; return ST_OUT_OF_MEM; } /* initialize */ for (i = 0; i < table->num_bins; i++) { table->bins[i] = 0; } /* copy data over */ for (i = 0; i < old_num_bins; i++) { ptr = old_bins[i]; while (ptr != NIL(st_table_entry)) { next = ptr->next; hash_val = do_hash(ptr->key, table); ptr->next = table->bins[hash_val]; table->bins[hash_val] = ptr; table->num_entries++; ptr = next; } } FREE(old_bins); return 1; } /* rehash */