Heap implementation based on a pairing-heap.
This heap implementations supports an arbitrary element type via a comparison
function. If you need a heap with elements ordered by integers, then it may be more
efficient to use a Timing_wheel.Priority_queue
, which is a heap implementation
specialized to integer keys, and with some other performance differences and usage
restrictions.
type 'a t
of_sexp and bin_io functions aren't supplied for heaps due to the difficulties in reconstructing the correct comparison function when de-serializing.
include sig ... end
val sexp_of_t : ('a ‑> Sexplib.Sexp.t) ‑> 'a t ‑> Sexplib.Sexp.t
Mutation of the heap during iteration is not supported, but there is no check to prevent it. The behavior of a heap that is mutated during iteration is undefined.
include Core_kernel.Container.S1 with type a t := a t
val mem : 'a t ‑> 'a ‑> equal:('a ‑> 'a ‑> bool) ‑> bool
Checks whether the provided element is there, using equal
.
val length : 'a t ‑> int
val is_empty : 'a t ‑> bool
val iter : 'a t ‑> f:('a ‑> unit) ‑> unit
val fold : 'a t ‑> init:'accum ‑> f:('accum ‑> 'a ‑> 'accum) ‑> 'accum
fold t ~init ~f
returns f (... f (f (f init e1) e2) e3 ...) en
, where e1..en
are the elements of t
val fold_result : 'a t ‑> init:'accum ‑> f:('accum ‑> 'a ‑> ('accum, 'e) Base.Result.t) ‑> ('accum, 'e) Base.Result.t
fold_result t ~init ~f
is a short-circuiting version of fold
that runs in the
Result
monad. If f
returns an Error _
, that value is returned without any
additional invocations of f
.
val fold_until : 'a t ‑> init:'accum ‑> f:('accum ‑> 'a ‑> ('accum, 'stop) Base.Container_intf.Continue_or_stop.t) ‑> ('accum, 'stop) Base.Container_intf.Finished_or_stopped_early.t
fold_until t ~init ~f
is a short-circuiting version of fold
. If f
returns Stop _
the computation ceases and results in that value. If f
returns
Continue _
, the fold will proceed.
val exists : 'a t ‑> f:('a ‑> bool) ‑> bool
Returns true
if and only if there exists an element for which the provided
function evaluates to true
. This is a short-circuiting operation.
val for_all : 'a t ‑> f:('a ‑> bool) ‑> bool
Returns true
if and only if the provided function evaluates to true
for all
elements. This is a short-circuiting operation.
val count : 'a t ‑> f:('a ‑> bool) ‑> int
Returns the number of elements for which the provided function evaluates to true.
val sum : (module Base.Commutative_group.S with type t = 'sum) ‑> 'a t ‑> f:('a ‑> 'sum) ‑> 'sum
Returns the sum of f i
for all i
in the container.
val find : 'a t ‑> f:('a ‑> bool) ‑> 'a option
Returns as an option
the first element for which f
evaluates to true.
val find_map : 'a t ‑> f:('a ‑> 'b option) ‑> 'b option
Returns the first evaluation of f
that returns Some
, and returns None
if there
is no such element.
val to_list : 'a t ‑> 'a list
val to_array : 'a t ‑> 'a array
val min_elt : 'a t ‑> cmp:('a ‑> 'a ‑> int) ‑> 'a option
Returns a minimum (resp maximum) element from the collection using the provided
cmp
function, or None
if the collection is empty. In case of a tie, the first
element encountered while traversing the collection is returned. The implementation
uses fold
so it has the same complexity as fold
.
val max_elt : 'a t ‑> cmp:('a ‑> 'a ‑> int) ‑> 'a option
Even though these two functions min_elt
and max_elt
are part of Container.S1, they
are documented separately to make sure there is no confusion. They are independent of
the comparison function used to order the heap. Instead, a traversal of the entire
structure is done using the provided cmp
function to find a min or max.
If you want to access the smallest element of the heap according to the heap's
comparison function in constant time, you should use top
.
val min_elt : 'a t ‑> cmp:('a ‑> 'a ‑> Core_kernel__.Import.int) ‑> 'a Core_kernel__.Import.option
val max_elt : 'a t ‑> cmp:('a ‑> 'a ‑> Core_kernel__.Import.int) ‑> 'a Core_kernel__.Import.option
val create : ?min_size:Core_kernel__.Import.int ‑> cmp:('a ‑> 'a ‑> Core_kernel__.Import.int) ‑> Core_kernel__.Import.unit ‑> 'a t
create ?min_size ~cmp
returns a new min-heap that can store min_size
elements
without reallocations, using ordering function cmp
.
The top of the heap is the smallest element as determined by the provided comparison
function. In particular, if cmp x y < 0
then x
will be "on top of" y
in the
heap.
Memory use can be surprising in that the underlying pool never shrinks, so current memory use will at least be proportional to the largest number of elements that the heap has ever held.
val of_array : 'a Core_kernel__.Import.array ‑> cmp:('a ‑> 'a ‑> Core_kernel__.Import.int) ‑> 'a t
min_size
(see create
) will be set to the size of the input array or list.
val of_list : 'a Core_kernel__.Import.list ‑> cmp:('a ‑> 'a ‑> Core_kernel__.Import.int) ‑> 'a t
val top : 'a t ‑> 'a Core_kernel__.Import.option
Returns the top (i.e., smallest) element of the heap.
val top_exn : 'a t ‑> 'a
val add : 'a t ‑> 'a ‑> Core_kernel__.Import.unit
val pop : 'a t ‑> 'a Core_kernel__.Import.option
pop
removes and returns the top (i.e. least) element.
val pop_exn : 'a t ‑> 'a
val pop_if : 'a t ‑> ('a ‑> Core_kernel__.Import.bool) ‑> 'a Core_kernel__.Import.option
pop_if t cond
returns Some top_element
of t
if it satisfies condition
cond
, removing it, or None
in any other case.
module Elt : sig ... end
add_removable t v
adds v
to t
, returning a token that can be used to delete
v
from t
in lg(n) amortized time.
Note that while add
doesn't allocate unless the underlying pool needs to be resized,
add_removable
always allocates. The Unsafe
module has a non-allocating
alternative.
val remove : 'a t ‑> 'a Elt.t ‑> Core_kernel__.Import.unit
If t
and token
are mismatched then behavior is undefined. Trying to
remove
an already removed token (by an earlier call to remove
or pop
for
instance) is a no-op, but keeping token
around after it has been removed may lead
to memory leaks since it has a reference to the heap.
val find_elt : 'a t ‑> f:('a ‑> Core_kernel__.Import.bool) ‑> 'a Elt.t Core_kernel__.Import.option
find_elt t ~f
. If f
is true for some element in t
, return an Elt.t
for
that element. This operation is O(n).
module Unsafe : sig ... end