(** 
    Run the QSP parser and apply the analyzer over it.

    See [syntax/S]
 *)
let parse :
    (module Qsp_syntax.S.Analyzer with type Location.repr = 'a) ->
    Lexbuf.t ->
    ('a, Qsp_syntax.Report.t) Result.t =
 fun (type a) (module S : Qsp_syntax.S.Analyzer with type Location.repr = a) ->
  let module Parser = Parser.Make (S) in
  let module IncrementalParser =
    Interpreter.Interpreter (Parser.MenhirInterpreter) in
  fun l ->
    let lexer = Lexbuf.tokenize Lexer.token l in

    let init = Parser.Incremental.main (fst (Lexbuf.positions l)) in

    let evaluation =
      try IncrementalParser.of_lexbuf lexer l init with
      | Lexer.LexError message ->
          let start_pos, end_pos = Lexbuf.positions l in
          let err =
            IncrementalParser.
              { code = Interpreter.Custom message; start_pos; end_pos }
          in
          Error err
      | Lexer.UnclosedQuote ->
          let start_pos, end_pos = Lexbuf.positions l in
          let err =
            IncrementalParser.
              { code = Interpreter.Custom "Unclosed text"; start_pos; end_pos }
          in
          Error err
    in

    Result.map_error
      (fun e ->
        let message =
          match e.IncrementalParser.code with
          | Interpreter.InvalidSyntax -> "Invalid Syntax"
          | Interpreter.UnrecoverableError -> "UnrecoverableError"
          | Interpreter.Custom msg -> msg
          | Interpreter.MenhirCode c ->
              let message_content =
                try Parser_messages.message c
                with Not_found ->
                  String.concat "" [ "(Error code "; string_of_int c; ")" ]
              in

              String.concat "" [ String.trim @@ message_content ]
        in
        let report = Qsp_syntax.Report.error (e.start_pos, e.end_pos) message in

        (* Discard the remaining file to read. The parser is now in a blank
           state, it does not make sense to keep feeding it with the new
           tokens. *)
        let () = try Lexer.discard l with _ -> () in

        report)
      evaluation