+This library implements type-checked dynamic hash tables. The hash
+table entries can be arbitrary structures. Usually they consist of key
+and value fields.
+
+lh_<type>_new() creates a new B<LHASH_OF(<type>> structure to store
+arbitrary data entries, and provides the 'hash' and 'compare'
+callbacks to be used in organising the table's entries. The B<hash>
+callback takes a pointer to a table entry as its argument and returns
+an unsigned long hash value for its key field. The hash value is
+normally truncated to a power of 2, so make sure that your hash
+function returns well mixed low order bits. The B<compare> callback
+takes two arguments (pointers to two hash table entries), and returns
+0 if their keys are equal, non-zero otherwise. If your hash table
+will contain items of some particular type and the B<hash> and
+B<compare> callbacks hash/compare these types, then the
+B<DECLARE_LHASH_HASH_FN> and B<IMPLEMENT_LHASH_COMP_FN> macros can be
+used to create callback wrappers of the prototypes required by
+lh_<type>_new(). These provide per-variable casts before calling the
+type-specific callbacks written by the application author. These
+macros, as well as those used for the "doall" callbacks, are defined
+as;
+
+ #define DECLARE_LHASH_HASH_FN(name, o_type) \
+ unsigned long name##_LHASH_HASH(const void *);
+ #define IMPLEMENT_LHASH_HASH_FN(name, o_type) \
+ unsigned long name##_LHASH_HASH(const void *arg) { \
+ const o_type *a = arg; \
+ return name##_hash(a); }
+ #define LHASH_HASH_FN(name) name##_LHASH_HASH
+
+ #define DECLARE_LHASH_COMP_FN(name, o_type) \
+ int name##_LHASH_COMP(const void *, const void *);
+ #define IMPLEMENT_LHASH_COMP_FN(name, o_type) \
+ int name##_LHASH_COMP(const void *arg1, const void *arg2) { \
+ const o_type *a = arg1; \
+ const o_type *b = arg2; \
+ return name##_cmp(a,b); }
+ #define LHASH_COMP_FN(name) name##_LHASH_COMP
+
+ #define DECLARE_LHASH_DOALL_FN(name, o_type) \
+ void name##_LHASH_DOALL(void *);
+ #define IMPLEMENT_LHASH_DOALL_FN(name, o_type) \
+ void name##_LHASH_DOALL(void *arg) { \
+ o_type *a = arg; \
+ name##_doall(a); }
+ #define LHASH_DOALL_FN(name) name##_LHASH_DOALL
+
+ #define DECLARE_LHASH_DOALL_ARG_FN(name, o_type, a_type) \
+ void name##_LHASH_DOALL_ARG(void *, void *);
+ #define IMPLEMENT_LHASH_DOALL_ARG_FN(name, o_type, a_type) \
+ void name##_LHASH_DOALL_ARG(void *arg1, void *arg2) { \
+ o_type *a = arg1; \
+ a_type *b = arg2; \
+ name##_doall_arg(a, b); }
+ #define LHASH_DOALL_ARG_FN(name) name##_LHASH_DOALL_ARG
+
+ An example of a hash table storing (pointers to) structures of type 'STUFF'
+ could be defined as follows;
+
+ /* Calculates the hash value of 'tohash' (implemented elsewhere) */
+ unsigned long STUFF_hash(const STUFF *tohash);
+ /* Orders 'arg1' and 'arg2' (implemented elsewhere) */
+ int stuff_cmp(const STUFF *arg1, const STUFF *arg2);
+ /* Create the type-safe wrapper functions for use in the LHASH internals */
+ static IMPLEMENT_LHASH_HASH_FN(stuff, STUFF);
+ static IMPLEMENT_LHASH_COMP_FN(stuff, STUFF);
+ /* ... */
+ int main(int argc, char *argv[]) {
+ /* Create the new hash table using the hash/compare wrappers */
+ LHASH_OF(STUFF) *hashtable = lh_STUFF_new(LHASH_HASH_FN(STUFF_hash),
+ LHASH_COMP_FN(STUFF_cmp));
+ /* ... */
+ }
+
+lh_<type>_free() frees the B<LHASH_OF(<type>> structure
+B<table>. Allocated hash table entries will not be freed; consider
+using lh_<type>_doall() to deallocate any remaining entries in the
+hash table (see below).
+
+lh_<type>_insert() inserts the structure pointed to by B<data> into
+B<table>. If there already is an entry with the same key, the old
+value is replaced. Note that lh_<type>_insert() stores pointers, the
+data are not copied.
+
+lh_<type>_delete() deletes an entry from B<table>.
+
+lh_<type>_retrieve() looks up an entry in B<table>. Normally, B<data>
+is a structure with the key field(s) set; the function will return a