Library
Module
Module type
Parameter
Class
Class type
Vectors (aka resizable arrays, growing arrays, dynamic arrays, etc.)
This module implements arrays that automatically expand as necessary. Its implementation uses a traditional array and replaces it with a larger array when needed (and elements are copied from the old array to the new one). The current implementation doubles the capacity when growing the array (and shrinks it whenever the number of elements comes to one fourth of the capacity).
The unused part of the internal array is filled with a dummy value, which is user-provided at creation time (and referred to below as ``the dummy value''). Consequently, vectors do not retain pointers to values that are not used anymore after a shrinking.
Vectors provide an efficient implementation of stacks, with a better locality of reference than list-based implementations (such as standard library Stack
). A stack interface is provided, similar to that of Stack
(though Vector.push
have arguments in the other way round). Inserting n
elements with Vector.push
has overall complexity O(n) i.e. each insertion has amortized constant time complexity.
Array
val create : ?capacity:int -> dummy:'a -> 'a t
create
returns a fresh vector of length 0
. All the elements of this new vector are initially physically equal to dummy
(in the sense of the ==
predicate). When capacity
is omitted, it defaults to 0.
val make : ?dummy:'a -> int -> 'a -> 'a t
make dummy n x
returns a fresh vector of length n
with all elements initialized with x
. If dummy
is omitted, x
is also used as a dummy value for this vector.
val init : dummy:'a -> int -> (int -> 'a) -> 'a t
init n f
returns a fresh vector of length n
, with element number i
initialized to the result of f i
. In other terms, init n f
tabulates the results of f
applied to the integers 0
to n-1
.
Raise Invalid_argument
if n < 0
or n > Sys.max_array_length
.
val resize : 'a t -> int -> unit
resize a n
sets the length of vector a
to n
.
The elements that are no longer part of the vector, if any, are internally replaced by the dummy value of vector a
, so that they can be garbage collected when possible.
Raise Invalid_argument
if n < 0
or n > Sys.max_array_length
.
val clear : 'a t -> unit
Discard all elements from a vector. This is equivalent to setting the size to 0 with resize
.
val is_empty : 'a t -> bool
Return true
if the given vector is empty, false
otherwise.
val length : 'a t -> int
Return the length (number of elements) of the given vector. Note: the number of memory words occupied by the vector can be larger.
val get : 'a t -> int -> 'a
get a n
returns the element number n
of vector a
. The first element has number 0
. The last element has number length a - 1
.
Raise Invalid_argument "Vector.get"
if n
is outside the range 0
to length a - 1
.
val set : 'a t -> int -> 'a -> unit
set a n x
modifies aector a
in place, replacing element number n
with x
.
Raise Invalid_argument "Vector.set"
if n
is outside the range 0 to length a - 1
.
sub a start len
returns a fresh vector of length len
, containing the elements number start
to start + len - 1
of vector a
.
val fill : 'a t -> int -> int -> 'a -> unit
fill a ofs len x
modifies the vector a
in place, storing x
in elements number ofs
to ofs + len - 1
.
Raise Invalid_argument "Vector.fill"
if ofs
and len
do not designate a valid subvector of a
.
blit a1 o1 a2 o2 len
copies len
elements from vector a1
, starting at element number o1
, to vector a2
, starting at element number o2
. It works correctly even if a1
and a2
are the same vector, and the source and destination chunks overlap.
Raise Invalid_argument "Vector.blit"
if o1
and len
do not designate a valid subvector of a1
, or if o2
and len
do not designate a valid subvector of a2
.
append a1 a2
returns a fresh vector containing the concatenation of the elements of a1
and a2
.
It works correctly even if a1
and a2
are the same vector.
merge_right a1 a2
moves all elements of a2
to the end of a1
. Empties a2
. Assumes a1
and a2
to be disjoint.
map f a
applies function f
to all the elements of a
, and builds a fresh vector with the results returned by f
.
Note: the dummy value of the returned vector is obtained by applying f
to the dummy value of a
. If this is not what you want, first create a new vector and then fill it with the value f (get a 0)
, f (get a 1)
, etc.
Same as Vector.map
, but the function is applied to the index of the element as first argument, and the element itself as second argument.
Note: the dummy value of the returned vector is obtained by applying f 0
to the dummy value of a
.
copy a
returns a copy of a
, that is, a fresh vector containing the same elements as a
.
val fold_left : 'b t -> ('a -> 'b -> 'a) -> 'a -> 'a
fold_left f x a
computes f (... (f (f x (get a 0)) (get a 1)) ...) (get a (n-1))
, where n
is the length of the vector a
.
val fold_right : 'b t -> ('b -> 'a -> 'a) -> 'a -> 'a
fold_right f a x
computes f (get a 0) (f (get a 1) ( ... (f (get a (n-1)) x) ...))
, where n
is the length of the vector a
.
val iter : ('a -> unit) -> 'a t -> unit
iter f a
applies function f
in turn to all the elements of a
. It is equivalent to f (get a 0); f (get a 1); ...; f (get a (length a - 1))
.
val iteri : (int -> 'a -> unit) -> 'a t -> unit
Same as Vector.iter
, but the function is applied to the index of the element as first argument, and the element itself as second argument.
Contrary to standard library's Stack
, module Vector
uses less space (between N and 2N words, instead of 3N) and has better data locality.
val push : 'a t -> 'a -> unit
push a x
appends x
at the end of vector a
, i.e., increases the size of a
by one and stores x
at the rightmost position.
Note: the order of the arguments is not that of Stack.push
.
val pop : 'a t -> 'a
pop a
removes and returns the rightmost element in vector a
, or raises Empty
if the stack is empty.
val pop_opt : 'a t -> 'a option
similar to pop
, but with an option instead of an exception
val top : 'a t -> 'a
top a
returns the rightmost element in vector a
, or raises Empty
if the vector is empty.
val top_opt : 'a t -> 'a option
similar to top
, but with an option instead of an exception