# The st package

## Symbol table package.

###

- ### External abstracts

- ### All abstracts

- ### External functions

- ### All functions

The st library provides functions to create, maintain, and query symbol tables.

    int
    st_add_direct(
      st_table * table,
      void * key,
      void * value
    )

  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.

  Side Effects None

    st_table *
    st_copy(
      st_table * old_table
    )

  Return a copy of old_table and all its members. (st_table *) 0 is returned if there was insufficient memory to do the copy.

  Side Effects None

    st_count(
       table
    )

  Returns the number of entries in the table `table'.

  Side Effects None

    int
    st_delete_int(
      st_table * table,
      void * keyp,
      int * value
    )

  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.

  Side Effects None

  See Also `st_delete`

    int
    st_delete(
      st_table * table,
      void * keyp,
      void * value
    )

  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.

  Side Effects None

  See Also `st_delete_int`

    int
    st_find_or_add(
      st_table * table,
      void * key,
      void * slot
    )

  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);

  Side Effects None

  See Also `st_find`

    int
    st_find(
      st_table * table,
      void * key,
      void * slot
    )

  Like st_find_or_add, but does not create an entry if one is not found.

  Side Effects None

  See Also `st_find_or_add`

    st_foreach_item_int(
       table,
       gen,
       key,
       value
    )

  An iteration macro which loops over all the entries in `table', setting `key' to point to the key and `value' to the associated value (if it is not nil). `value' is assumed to be a pointer to an integer. `gen' is a generator variable used internally. Sample usage:

       char *key;

       int value;

       st_generator *gen;

       st_foreach_item_int(table, gen, &key, &value) {

       process_item(value);

       }

  Side Effects None

  See Also `st_foreach_item st_foreach`

    st_foreach_item(
       table,
       gen,
       key,
       value
    )

  An iteration macro which loops over all the entries in `table', setting `key' to point to the key and `value' to the associated value (if it is not nil). `gen' is a generator variable used internally. Sample usage:

       char *key, *value;

       st_generator *gen;

       st_foreach_item(table, gen, &key, &value) {

       process_item(value);

       }

  Side Effects None

  See Also `st_foreach_item_int st_foreach`

    int
    st_foreach(
      st_table * table,
      ST_PFSR  func,
      char * arg
    )

  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.

  Side Effects None

  See Also `st_foreach_item st_foreach_item_int`

    void
    st_free_gen(
      st_generator * gen
    )

  After generating all items in a generation sequence, this routine must be called to reclaim the resources associated with `gen'.

  Side Effects None

  See Also `st_init_gen`

    void
    st_free_table(
      st_table * table
    )

  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).

  Side Effects None

  See Also `st_init_table st_init_table_with_params`

    int
    st_gen_int(
      st_generator * gen,
      void * key_p,
      int * value_p
    )

  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.

  Side Effects None

  See Also `st_gen`

    int
    st_gen(
      st_generator * gen,
      void * key_p,
      void * value_p
    )

  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.

  Side Effects None

  See Also `st_gen_int`

    st_generator *
    st_init_gen(
      st_table * table
    )

  Returns a generator handle which when used with st_gen() will progressively return each (key, value) record in `table'.

  Side Effects None

  See Also `st_free_gen`

    st_table *
    st_init_table_with_params(
      ST_PFICPCP  compare,
      ST_PFICPI  hash,
      int  size,
      int  density,
      double  grow_factor,
      int  reorder_flag
    )

  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);

  Side Effects None

  See Also `st_init_table st_free_table`

    st_table *
    st_init_table(
      ST_PFICPCP  compare,
      ST_PFICPI  hash
    )

  Create and initialize a table with the comparison function compare_fn and hash function hash_fn. compare_fn is

       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 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.

  Side Effects None

  See Also `st_init_table_with_params st_free_table`

    int
    st_insert(
      st_table * table,
      void * key,
      void * value
    )

  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.

  Side Effects None

    st_is_member(
       table,
       key
    )

  Returns 1 if there is an entry under `key' in `table', 0 otherwise.

  Side Effects None

  See Also `st_lookup`

    int
    st_lookup_int(
      st_table * table,
      void * key,
      int * value
    )

  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.

  Side Effects None

  See Also `st_lookup`

    int
    st_lookup(
      st_table * table,
      void * key,
      void * value
    )

  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.

  Side Effects None

  See Also `st_lookup_int`

    int
    st_numcmp(
      const char * x,
      const char * y
    )

  integer number comparison function.

  Side Effects None

  See Also `st_init_table st_numhash`

    int
    st_numhash(
      char * x,
      int  size
    )

  Integer number hash function.

  Side Effects None

  See Also `st_init_table st_numcmp`

    int
    st_ptrcmp(
      const char * x,
      const char * y
    )

  Pointer comparison function.

  Side Effects None

  See Also `st_init_table st_ptrhash`

    int
    st_ptrhash(
      char * x,
      int  size
    )

  Pointer hash function.

  Side Effects None

  See Also `st_init_table st_ptrcmp`

    int
    st_strhash(
      char * string,
      int  modulus
    )

  String hash function.

  Side Effects None

  See Also `st_init_table`

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