quantum_package/ocaml/String_ext.ml

include String

(** Split a string on a given character *)
let split ?(on=' ') str = 
  split_on_char on str
(*
    let rec do_work ?(accu=[]) ?(left="") = function
    | "" -> List.rev (left::accu)
    | s  ->
        let new_s =
            (length s) - 1
            |> sub s 1 
        in
        if (s.[0] = on) then
            let new_accu = 
                left :: accu
            in
            do_work ~accu:new_accu new_s
        else
            let new_left =
                concat "" [ left ; make 1 s.[0] ]
            in
            do_work ~accu ~left:new_left new_s
    in
    do_work str
*)
  

(** Strip blanks on the left of a string *)
let ltrim s =
    let rec do_work s l =
        match s.[0] with
        | '\n'
        | ' ' -> do_work (sub s 1 (l-1)) (l-1)
        | _ -> s
    in
    let l =
        length s
    in
    if (l > 0) then
        do_work s l
    else
        s

(** Strip blanks on the right of a string *)
let rtrim s =
    let rec do_work s l =
        let newl =
            l-1
        in
        match s.[newl] with
        | '\n'
        | ' ' -> do_work (sub s 0 (newl)) (newl)
        | _ -> s
    in
    let l = 
        length s
    in
    if (l > 0) then
        do_work s l
    else
        s


(** Strip blanks on the right and left of a string *)
let strip = String.trim


(** Split a string in two pieces when a character is found the 1st time from the left *)
let lsplit2_exn ?(on=' ') s =
    let length = 
        String.length s
    in
    let rec do_work i = 
        if (i = length) then
           begin
              raise Not_found
           end
        else if (s.[i] = on) then
           ( String.sub s 0 i, 
             String.sub s (i+1) (length-i-1) )
        else
           do_work (i+1)
    in
    do_work 0


(** Split a string in two pieces when a character is found the 1st time from the right *)
let rsplit2_exn ?(on=' ') s =
    let length = 
        String.length s
    in
    let rec do_work i = 
        if (i = -1) then
           begin
              raise Not_found
           end
        else if (s.[i] = on) then
           ( String.sub s 0 i, 
             String.sub s (i+1) (length-i-1) )
        else
           do_work (i-1)
    in
    do_work length


let lsplit2 ?(on=' ') s =
  try
    Some (lsplit2_exn ~on s) 
  with
  | Not_found -> None


let rsplit2 ?(on=' ') s =
  try
    Some (rsplit2_exn ~on s) 
  with
  | Not_found -> None


let to_list s =
  Array.init (String.length s) (fun i -> s.[i])
  |> Array.to_list


let fold ~init ~f s =
    to_list s
    |> List.fold_left f init 

  
let is_prefix ~prefix s =
  let len =
    String.length prefix
  in
  if len > String.length s then
    false
  else
    prefix = String.sub s 0 len 


let of_char c =
  String.make 1 c