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|
module M : sig
type 'a t = 'a array array
val empty : int -> int -> 'a -> 'a t
(** [empty rows columns initial] is an empty 2D array of size [rows] * [columns]
where each element in the array is initialized to [initial]. *)
val of_list : 'a list list -> 'a t
(** *)
val of_string : string -> string t
(** [of_string str] is a 2D array where every character is an element. *)
val get : 'a t -> int -> int -> 'a
(** [get matrix x y] is an alias for [matrix.(y).(x)] *)
val pp : ('a -> string) -> 'a t -> string
(** [pp matrix string_of_elt] is the string representation of the [matrix]
where [string_of_elt] is called on each element. *)
end = struct
type 'a t = 'a array array
let empty cols rows initial = Array.make_matrix cols rows initial
let of_list lst = Array.of_list @@ List.map Array.of_list lst
let of_string str =
let lines =
str |> String.split_on_char '\n'
|> List.filter_map (fun line ->
let trimmed = String.trim line in
if trimmed <> "" then Some trimmed else None )
in
let char_lst =
List.map
(fun s -> s |> String.to_seq |> List.of_seq |> List.map Char.escaped)
lines
in
of_list char_lst
let get matrix x y = matrix.(y).(x)
let pp string_of_elt matrix =
Array.fold_left
(fun col_acc arr ->
let row =
Array.fold_left
(fun row_acc elt -> row_acc ^ string_of_elt elt)
"" arr
in
if col_acc = "" then row else col_acc ^ "\n" ^ row )
"" matrix
end
let%expect_test "matrix created from input is pretty-printed as the same matrix"
=
let example =
{|..@@.@@@@.
@@@.@.@.@@
@@@@@.@.@@
@.@@@@..@.
@@.@@@@.@@
.@@@@@@@.@
.@.@.@.@@@
@.@@@.@@@@
.@@@@@@@@.
@.@.@@@.@.|}
in
print_string @@ M.pp (fun s -> s) @@ M.of_string example ;
[%expect
{|..@@.@@@@.
@@@.@.@.@@
@@@@@.@.@@
@.@@@@..@.
@@.@@@@.@@
.@@@@@@@.@
.@.@.@.@@@
@.@@@.@@@@
.@@@@@@@@.
@.@.@@@.@.|}]
let%expect_test "direct access of the matrix is in form matrix.(y).(x)" =
let example =
{|..@@.@@@@.
@@@.@.@.@@
@@@@@.@.@@
@.@@@@..@.
@@.@@@@.@@
.@@@@@@@.@
.@.@.@.@@@
@.@@@.@@@@
.@@@@@@@@.
@.@.@@@.@.|}
in
let matrix = M.of_string example in
print_string matrix.(0).(0) ;
[%expect "."] ;
print_string matrix.(0).(1) ;
[%expect "."] ;
print_string matrix.(0).(2) ;
[%expect "@"] ;
print_string matrix.(0).(3) ;
[%expect "@"] ;
print_string matrix.(0).(4) ;
[%expect "."] ;
print_string matrix.(0).(5) ;
[%expect "@"] ;
print_string matrix.(0).(6) ;
[%expect "@"] ;
print_string matrix.(0).(7) ;
[%expect "@"] ;
print_string matrix.(0).(8) ;
[%expect "@"] ;
print_string matrix.(0).(9) ;
[%expect "."]
let%expect_test "[M.get matrix x y] is an alias for [matrix.(y).(x)]" =
let example =
{|..@@.@@@@.
@@@.@.@.@@
@@@@@.@.@@
@.@@@@..@.
@@.@@@@.@@
.@@@@@@@.@
.@.@.@.@@@
@.@@@.@@@@
.@@@@@@@@.
@.@.@@@.@.|}
in
let matrix = M.of_string example in
print_string @@ M.get matrix 0 0 ;
[%expect "."] ;
print_string @@ M.get matrix 1 0 ;
[%expect "."] ;
print_string @@ M.get matrix 2 0 ;
[%expect "@"] ;
print_string @@ M.get matrix 3 0 ;
[%expect "@"] ;
print_string @@ M.get matrix 4 0 ;
[%expect "."] ;
print_string @@ M.get matrix 5 0 ;
[%expect "@"] ;
print_string @@ M.get matrix 6 0 ;
[%expect "@"] ;
print_string @@ M.get matrix 7 0 ;
[%expect "@"] ;
print_string @@ M.get matrix 8 0 ;
[%expect "@"] ;
print_string @@ M.get matrix 9 0 ;
[%expect "."]
|
