module type S = sig .. end
type 'a list_
The underlying list type the cursor points to.
type 'a cursor
The type of list cursors. A cursor can be thought of a
pointer into the middle of a list. More specifically,
cursors point to edges between list elements, not elements
directly. A cursor can be move to the left (towards the
front of the list) or to the right (towards the back of the
list) and supports updating the list at the current position
efficiently.
val to_cursor : 'a list_ -> 'a cursor
to_cursor t Create a cursor that points to the beginning of
list t. Runs in O(1) time and space.
val from_cursor : 'a cursor -> 'a list_
from_cursor curs Return the list that is pointed to by
curs. Runs in O(n) time and O(1) stack space where n is the
number of elements to the left of curs.
val at_front : 'a cursor -> bool
at_front curs Returns true if there are no elements to the
left of curs. Runs in O(1) time and stack space.
val at_back : 'a cursor -> bool
at_end curs Returns true if there are no elements to the
right of curs. Runs in O(1) time and stack space.
val move_next : 'a cursor -> 'a cursor
move_left curs Moves the cursor one element to the left. If
there are no elements to the left of curs (i.e., curs
points to the front of the list), it raises Failure
"move_left". Runs in O(1) time and stack space.
val move_prev : 'a cursor -> 'a cursor
move_right curs Moves the cursor one element to the right.
If there are no elements to the right of curs (i.e., curs
points to the end of the list), it raises Failure
"move_right". Runs in O(1) time and stack space.
val goto_front : 'a cursor -> 'a cursor
goto_front curs Moves the cursor to the front of the
list. Runs in O(n) time and O(1) stack space where n is the
number of elements to the left of curs.
val goto_back : 'a cursor -> 'a cursor
goto_back curs Moves the cursor to the back of the list.
Runs in O(n) time and O(1) stack space where n is the number
of elements to the right of curs.
val value : 'a cursor -> 'a option
If the cursor currently points to an element x, return that
element as Some x, otherwise return None.
val list : 'a cursor -> 'a list_
list curs Returns all of the elements to the right of curs
as a 'a list_. Runs in O(1) time and stack space.
val replace_list : 'a list_ ->
'a cursor -> 'a cursor
replace_list l curs Replaces the list of elements to the
right of curs with l. Runs in O(1) time and stack
space.