Hash Tables demonstration

[Pjot]

All,

Though BaCon has a native implementation for key-value structures (by using associative arrays) there is a way to do this using hash tables, and in a more sophisticated way.

The below example uses uthash, an open-source implementation completely built on C macros. It fits in only one C header file and has very powerful features.

Regards
Peter


' UThash header file
PRAGMA INCLUDE uthash-master/src/uthash.h

' Optionally choose HASH function
PRAGMA OPTIONS -DHASH_FUNCTION=HASH_BER

OPTION PARSE FALSE

' Main key-value store
RECORD Hash_Table
   LOCAL key TYPE char*
   LOCAL value TYPE char*
   LOCAL hh TYPE UT_hash_handle
END RECORD

' Main data tree
DECLARE data = NULL TYPE Hash_Table_type*

' Add items
SUB Add_Data(char *idx, char *info)

   LOCAL entry TYPE Hash_Table_type*

   entry = malloc(SIZEOF(Hash_Table_type))

   entry->key = strdup(idx)
   entry->value = strdup(info)

   HASH_ADD_STR(data, key, entry)

END SUB

' Search items
FUNCTION Find_Data$(char *idx) TYPE char*

   LOCAL find = NULL TYPE Hash_Table_type*

   HASH_FIND_STR(data, idx, find)

   RETURN find->value

END FUNCTION

' Example
Add_Data("one", "English")
Add_Data("two", "Dutch")
Add_Data("three", "Spanish")
Add_Data("four", "Italian")

PRINT "Total entries: ", HASH_COUNT(data)

PRINT "Entry: ", Find_Data$("three")


[vovchik]

Dear Peter,

Thanks. Just tested and it works - and is easy to use....

With kind regards,
vovchik