NAME

       lyst - library for manipulating generalized doubly linked lists

SYNOPSIS

           #include "lyst.h"

           typedef int  (*LystCompareFn)(void *s1, void *s2);
           typedef void (*LystCallback)(LystElt elt, void *userdata);

           [see description for available functions]

DESCRIPTION

       The "lyst" library uses two types of objects, Lyst objects and LystElt objects.  A Lyst
       knows how many elements it contains, its first and last elements, the memory manager used
       to create/destroy the Lyst and its elements, and how the elements are sorted.  A LystElt
       knows its content (normally a pointer to an item in memory), what Lyst it belongs to, and
       the LystElts before and after it in that Lyst.

       Lyst lyst_create(void)
           Create and return a new Lyst object without any elements in it.  All operations
           performed on this Lyst will use the allocation/deallocation functions of the default
           memory manager "std" (see memmgr(3)).  Returns NULL on any failure.

       Lyst lyst_create_using(unsigned memmgrId)
           Create and return a new Lyst object without any elements in it.  All operations
           performed on this Lyst will use the allocation/deallocation functions of the specified
           memory manager (see memmgr(3)).  Returns NULL on any failure.

       void lyst_clear(Lyst list)
           Clear a Lyst, i.e. free all elements of list, calling the Lyst's deletion function if
           defined, but without destroying the Lyst itself.

       void lyst_destroy(Lyst list)
           Destroy a Lyst.  Will free all elements of list, calling the Lyst's deletion function
           if defined.

       void lyst_compare_set(Lyst list, LystCompareFn compareFn)
       LystCompareFn lyst_compare_get(Lyst list)
           Set/get comparison function for specified Lyst.  Comparison functions are called with
           two Lyst element data pointers, and must return a negative integer if first is less
           than second, 0 if both are equal, and a positive integer if first is greater than
           second (i.e., same return values as strcmp(3)).  The comparison function is used by
           the lyst_insert(), lyst_search(), lyst_sort(), and lyst_sorted() functions.

       void lyst_direction_set(Lyst list, LystSortDirection direction)
           Set sort direction (either LIST_SORT_ASCENDING or LIST_SORT_DESCENDING) for specified
           Lyst.  If no comparison function is set, then this controls whether new elements are
           added to the end or beginning (respectively) of the Lyst when lyst_insert() is called.

       void lyst_delete_set(Lyst list, LystCallback deleteFn, void *userdata)
           Set user deletion function for specified Lyst.  This function is automatically called
           whenever an element of the Lyst is deleted, to perform any user-required processing.
           When automatically called, the deletion function is passed two arguments: the element
           being deleted and the userdata pointer specified in the lyst_delete_set() call.

       void lyst_insert_set(Lyst list, LystCallback insertFn, void *userdata)
           Set user insertion function for specified Lyst.  This function is automatically called
           whenever a Lyst element is inserted into the Lyst, to perform any user-required
           processing.  When automatically called, the insertion function is passed two
           arguments: the element being inserted and the userdata pointer specified in the
           lyst_insert_set() call.

       unsigned long lyst_length(Lyst list)
           Return the number of elements in the Lyst.

       LystElt lyst_insert(Lyst list, void *data)
           Create a new element whose content is the pointer value data and insert it into the
           Lyst.  Uses the Lyst's comparison function to select insertion point, if defined;
           otherwise adds the new element at the beginning or end of the Lyst, depending on the
           Lyst sort direction setting.  Returns a pointer to the newly created element, or NULL
           on any failure.

       LystElt lyst_insert_first(Lyst list, void *data)
       LystElt lyst_insert_last(Lyst list, void *data)
           Create a new element and insert it at the beginning/end of the Lyst.  If these
           functions are used when inserting elements into a Lyst with a defined comparison
           function, then the Lyst may get out of order and future calls to lyst_insert() can put
           new elements in unpredictable locations.  Returns a pointer to the newly created
           element, or NULL on any failure.

       LystElt lyst_insert_before(LystElt element, void *data)
       LystElt lyst_insert_after(LystElt element, void *data)
           Create a new element and insert it before/after the specified element.  If these
           functions are used when inserting elements into a Lyst with a defined comparison
           function, then the Lyst may get out of order and future calls to lyst_insert can put
           new elements in unpredictable locations.  Returns a pointer to the newly created
           element, or NULL on any failure.

       void lyst_delete(LystElt element)
           Delete the specified element from its Lyst and deallocate its memory.  Calls the user
           delete function if defined.

       LystElt lyst_first(Lyst list)
       LystElt lyst_last(Lyst list)
           Return a pointer to the first/last element of a Lyst.

       LystElt lyst_next(LystElt element)
       LystElt lyst_prev(LystElt element)
           Return a pointer to the element following/preceding the specified element.

       LystElt lyst_search(LystElt element, void *searchValue)
           Find the first matching element in a Lyst starting with the specified element.
           Returns NULL if no matches are found.  Uses the Lyst's comparison function if defined,
           otherwise searches from the given element to the end of the Lyst.

       Lyst lyst_lyst(LystElt element)
           Return the Lyst to which the specified element belongs.

       void* lyst_data(LystElt element)
       void* lyst_data_set(LystElt element, void *data)
           Get/set the pointer value content of the specified Lyst element.  The set routine
           returns the element's previous content, and the delete function is not called.  If the
           lyst_data_set() function is used on an element of a Lyst with a defined comparison
           function, then the Lyst may get out of order and future calls to lyst_insert() can put
           new elements in unpredictable locations.

       void lyst_sort(Lyst list)
           Sort the Lyst based on the current comparison function and sort direction.  A stable
           insertion sort is used that is very fast when the elements are already in order.

       int lyst_sorted(Lyst list)
           Determine whether or not the Lyst is sorted based on the current comparison function
           and sort direction.

       void lyst_apply(Lyst list, LystCallback applyFn, void *userdata)
           Apply the function applyFn automatically to each element in the Lyst.  When
           automatically called, applyFn is passed two arguments: a pointer to an element, and
           the userdata argument specified in the call to lyst_apply().  applyFn should not
           delete or reorder the elements in the Lyst.

SEE ALSO

       memmgr(3), psm(3)