49 lines
1.2 KiB
OCaml
49 lines
1.2 KiB
OCaml
open Printf
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exception Reset_line (* used to indicate ^C is pressed *)
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let version = "%%VERSION%%"
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let error_to_string e =
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try raise e with
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| Lex.Token_not_found -> sprintf "invalid token"
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| Parser.Expected t -> sprintf "expected %s" t
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| Parser.Unexpected_token t -> sprintf "unexpected token \"%s\"" t
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| Ast.Invalid_type t -> sprintf "invalid type %s" (Ast.Type.to_string t)
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| Failure f -> sprintf "error on %s" f
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| Division_by_zero -> "cannot divide by zero"
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| _ -> raise e
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let print_error e =
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printf "error: %s\n" @@ error_to_string e
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(* read-eval-print *)
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let rep () : unit =
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printf "> ";
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let line = read_line () in
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if line = "quit" then raise Exit;
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let ans =
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line
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|> Lex.tokenize
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|> Parser.parse
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|> Eval.eval
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in
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match ans with
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| Nop -> ()
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| _ -> printf "%s\n" @@ Ast.Value.to_string ans
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let init_repl () =
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let sigintf _ = raise Reset_line in
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Sys.(set_signal sigint (Signal_handle sigintf))
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(* simple REPL with error handling *)
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let rec repl () : unit =
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try rep (); repl () with
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| Exit | End_of_file -> ()
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| Reset_line -> printf "\n"; repl ()
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| e -> print_error e; repl ()
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let () =
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init_repl ();
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printf "Configurable Evaluator %s\n" version; (* banner *)
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repl ()
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