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open BatList
open BatString
open List
open BatLazyList
open BatIO
open BatPrintf
type 'a state =
| Eof
| State of 'a
type 'a report = Report of ('a state * string * 'a report) list
let ( &&& ) (Report l) (Report l') = Report (l @ l')
let debug_mode = ref false
(** {3 Positions} *)
module Source =
struct
type ('a, 'b) t = ('a * 'b) BatLazyList.t
let of_lazy_list l init f =
let rec aux l acc = match get l with
| None -> nil
| Some (h, t) ->
let acc' = f h acc in
lazy( Cons ((h, acc'), (aux t acc')))
in aux l init
let of_enum l =
of_lazy_list (of_enum l)
open Lexing
(**TODO: Handle EOF !*)
let of_lexer l = assert false
(** LazyList.of_enum (BatEnum.from (fun () ->
l.refill_buff l;
(l.lex_buffer, (l.lex_start_p, l.lex_curr_p))))*)
let get_state l = match peek l with
| Some (_, s) -> State s
| None -> Eof
let set_full_state l init f =
let rec aux l acc = match get l with
| None -> nil
| Some ((h, _), t) ->
let acc' = f h acc in
lazy( Cons ((h, acc'), (aux t acc')))
in aux l init
end
open Source
type ('a, 'b, 'c) result =
| Success of 'b * ('a, 'c) Source.t (**Succeed and consume.*)
| Backtrack of 'b * 'c report * ('a, 'c) Source.t (**Succeed because of backtracking, typically without consuming.*)
| Setback of 'c report (**Error, backtracking in progress.*)
| Failure of 'c report (**Fatal error.*)
type ('a, 'b, 'c) t = ('a, 'c) Source.t -> ('a, 'b, 'c) result
let apply p e = p e(**To improve reusability*)
(** {3 Error-handling} *)
(*exception Backtrack of Obj.t report*)
(**Recoverable error.
These errors are caused by [fail].*)
(*exception Fail of Obj.t report*)
(**Fatal error.
These errors are caused by [must].*)
let fail e = Setback (Report [])
let succeed v e = Success (v, e)
let backtracked v r e = Backtrack (v, r, e)
let return = succeed
let fatal e = Failure (Report [])
(* Primitives *)
let satisfy f e = match get e with
| Some ((x,_),t) when f x -> succeed x t
| _ -> fail e
let depth = ref 0
let label s p e =
if BatString.is_empty s then
match apply p e with
| Success _ as x -> x
| Setback c -> Setback (Report [])
| Failure c -> Failure (Report [])
| Backtrack (b, c, t) -> Backtrack (b, Report [], t)
else
let make_report c = Report [get_state e, s, c] in
if !debug_mode then
begin
eprintf "%*s>>> %s\n" !depth " " s;
incr depth;
flush_all ()
end;
match apply p e with
| Success _ as x ->
if !debug_mode then begin
decr depth;
eprintf "%*s<<< %s\n" !depth " " s;
flush_all ()
end;
x
| Setback c ->
if !debug_mode then begin
decr depth;
eprintf "%*s^^^ %s\n" !depth " " s;
flush_all ()
end;
Setback (make_report c)
| Failure c ->
if !debug_mode then begin
decr depth;
eprintf "%*s!!! %s\n" !depth " " s;
flush_all ()
end;
Failure (make_report c)
| Backtrack (b, c, t) ->
if !debug_mode then begin
decr depth;
eprintf "%*s/// %s\n" !depth " " s;
flush_all ()
end;
Backtrack (b, make_report c, t)
let must p e = match apply p e with
| Setback x -> Failure x
| y -> y
let should p e = match apply p e with
| Failure x -> Setback x
| y -> y
let either l e =
let rec aux err = function
| [] -> Setback (Report err)
| h::t -> match apply h e with
| Success _
| Failure _
| Backtrack (_, _, _) as result -> result
| Setback (Report labels) -> aux (err @ labels) t
in aux [] l
let ( <|> ) p1 p2 = either [p1;p2]
let maybe p e = match apply p e with
| Setback c -> Backtrack (None, c, e)
| Success (result, rest) -> Success (Some result, rest)
| Backtrack (result, report, rest) -> Backtrack (Some result, report, rest)
| Failure _ as result -> result
let (~?) = maybe
(*
[bind m f e]
If [m] succeeded by backtracking and [f] fails or
succeeds by backtracking, merge the reports of [m] and [f].
*)
let bind m f e = match apply m e with
| Setback _ | Failure _ as result -> result
| Success (result, rest) -> apply f result rest
| Backtrack (result, report, rest) ->
match apply f result rest with
| Backtrack (result', report', rest') -> Backtrack (result', report &&& report', rest')
| Setback report' -> Setback (report &&& report')
| Failure report' -> Failure (report &&& report')
| Success _ as result -> result
let ( >>= ) = bind
let ( >>> ) p q =
p >>= fun _ -> q
let cons p q =
p >>= fun p_result ->
q >>= fun q_result ->
return (p_result::q_result)
let ( >:: ) = cons
let state e = succeed (get_state e) e
let eof e = label "End of file" (fun e -> match get e with
| None -> succeed () e
| _ -> fail e) e
let any e = label "Anything" (fun e -> match get e with
| None -> fail e
| Some ((x,_),t) -> succeed x t) e
let zero_plus ?sep p e =
let p' = match sep with
| None -> p
| Some s -> s >>> p
in
let rec aux acc l = match apply p' l with
| Success (x, rest) -> aux (x::acc) rest
| Backtrack (result, report, rest) -> backtracked (List.rev (result::acc)) report rest
| Setback report -> backtracked (List.rev acc) report l
| Failure _ as result -> result
in match apply p e with
| Success (x, rest) -> aux [x] rest
| Backtrack (result, report, rest) -> backtracked [result] report rest
| Setback report -> backtracked [] report e
| Failure _ as result -> result
let ( ~* ) p = zero_plus p
let ignore_zero_plus ?sep p e =
let p' = match sep with
| None -> p
| Some s -> s >>> p
in
let rec aux l = match apply p' l with
| Success (x, rest) -> aux rest
| Backtrack (result, report, rest) -> backtracked () report rest
| Setback report -> backtracked () report l
| Failure _ as result -> result
in match apply p e with
| Success (_, rest) -> aux rest
| Backtrack (result, report, rest) -> backtracked () report rest
| Setback report -> backtracked () report e
| Failure _ as result -> result
let one_plus ?sep p = p >::
match sep with
| None -> zero_plus p
| Some s -> zero_plus (s >>> p)
let ( ~+ ) p = one_plus p
let ignore_one_plus ?sep p = p >>>
match sep with
| None -> ignore_zero_plus p
| Some s -> ignore_zero_plus (s >>> p)
(** [prefix t l] returns [h] such that [[h::t] = l]*)
let prefix suffix l =
let rec aux acc rest = match get rest with
| None -> []
| Some (h, t) when t == suffix -> List.rev (h::acc)
| Some (h, t) -> aux (h::acc) t
in aux [] l
let scan p e =
let just_prefix rest = List.map fst (prefix rest e) in
match apply p e with (*First proceed with parsing*)
| Success (result, rest) -> succeed (just_prefix rest) rest
| Backtrack (result, report, rest) -> backtracked (just_prefix rest) report rest
| Setback _ | Failure _ as result -> result
let lookahead p e = match apply p e with
| Setback c -> Backtrack (None, c, e)
| Success (result, _) -> Success (Some result, e)
| Backtrack (result, report, _) -> Backtrack (Some result, report, e)
| Failure _ as result -> result
let interpret_result = function
| Setback f | Failure f -> BatPervasives.Bad f
| Success (r, _) | Backtrack (r, _, _) -> BatPervasives.Ok r
let suspend : ('a, 'b, 'c) t -> ('a, (unit -> ('b, 'c report) BatPervasives.result), 'c) t = fun s e ->
let resume () = interpret_result (s e) in
Success (resume, e)
let run p e = interpret_result (apply p e)
let source_map p e =
let rec aux e = match peek e with
| None -> nil
| Some (_, c) -> match apply p e with
| Success (result, rest) -> lazy (Cons ((result, c), (aux rest)))
| Backtrack (result, _, rest) -> lazy (Cons ((result, c), (aux rest)))
| Setback _ | Failure _ -> nil (*@TODO: improve error reporting !*)
in aux e
(**
{3 Utilities}
*)
let filter f p =
p >>= fun x ->
if f x then return x
else fail
let exactly x = satisfy (( = ) x)
let post_map f p =
p >>= fun x -> return (f x)
let times n p =
let rec aux acc i = if i > 0 then p >>= fun x -> (aux (x::acc) ( i - 1 ))
else return acc
in (aux [] n) >>= fun x -> return (List.rev x)
let ( ^^ ) p n = times n p
let one_of l e =
let exists x = List.exists (( = ) x) l in
satisfy exists e
let none_of l e =
let for_all x = List.for_all (( <> ) x) l in
satisfy for_all e
let range a b = satisfy (fun x -> a <= x && x <= b)
let sat f = (satisfy f) >>> return ()
module Infix = struct
let (<|>), (~?), (>>=), (>>>), (>::), ( ~* ), (~+), (^^) = (<|>), (~?), (>>=), (>>>), (>::), ( ~* ), (~+), (^^)
end
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