mirror of
https://github.com/MorizzG/MLox.git
synced 2025-12-06 04:22:41 +00:00
moved mutable part of state inside mutable field
since only `tokens` is actually mutable we can make that field mutable, and hence not have to deal with `state ref`s, and only have a single mutating function, i.e. `advance`.
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parent
be28dad67e
commit
6206ee4a00
1 changed files with 41 additions and 41 deletions
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@ -6,29 +6,29 @@ open Lexer
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open Stmt
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type parse_result = (stmt_node list, parser_error list) result
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type state = { mutable tokens : token list; is_in_loop : bool }
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type stmt_result = (stmt_node, parser_error) result
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type expr_result = (expr_node, parser_error) result
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type state = { tokens : token list; is_in_loop : bool }
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let with_is_in_loop (f : state ref -> stmt_result) (state : state ref) : stmt_result =
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let was_in_loop = !state.is_in_loop in
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state := { !state with is_in_loop = true };
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let result = f state in
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state := { !state with is_in_loop = was_in_loop };
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result
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let with_is_in_loop (f : state -> 'a) (state : state) : 'a =
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let state = { state with is_in_loop = true } in
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f state
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let make_state tokens = ref { tokens; is_in_loop = false }
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let is_at_end state = (List.hd !state.tokens).token_type = Eof
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let advance state = state := { !state with tokens = List.tl !state.tokens }
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let make_state tokens = { tokens; is_in_loop = false }
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let is_at_end state =
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assert (not (List.is_empty state.tokens));
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(List.hd state.tokens).token_type = Eof
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let advance state = state.tokens <- List.tl state.tokens
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let next state =
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assert (not ((List.hd !state.tokens).token_type = Eof));
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let token = List.hd !state.tokens in
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let token = List.hd state.tokens in
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advance state;
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token
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let peek state = List.hd !state.tokens
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let peek_tt (state : state ref) : token_type = (peek state).token_type
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let peek state = List.hd state.tokens
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let peek_tt (state : state) : token_type = (peek state).token_type
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let cur_pos state = (peek state).pos
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let advance_if state tt =
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@ -38,7 +38,7 @@ let advance_if state tt =
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else false
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let consume state tt =
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if advance_if state tt then Ok ()
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if advance_if state tt then Ok state
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else
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let pos = cur_pos state in
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let tt' = peek_tt state in
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@ -59,8 +59,8 @@ let matches state tts =
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let f = ( = ) (peek_tt state) in
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Array.fold_left (fun acc tt -> acc || f tt) false tts
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let collect_chain (state : state ref) (tts : token_type array)
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(higher_prec : state ref -> expr_result) : ((expr_node * token) list, parser_error) result =
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let collect_chain (state : state) (tts : token_type array) (higher_prec : state -> expr_result) :
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((expr_node * token) list, parser_error) result =
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let rec collect_chain_rec (acc : (expr_node * token) list) =
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if (not (is_at_end state)) && matches state tts then
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let token = next state in
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@ -69,9 +69,9 @@ let collect_chain (state : state ref) (tts : token_type array)
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collect_chain_rec acc
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else Ok acc
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in
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collect_chain_rec [] |> Result.map (fun l -> List.rev l)
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collect_chain_rec [] |> Result.map List.rev
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let primary (state : state ref) : expr_result =
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let primary (state : state) : expr_result =
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let pos = cur_pos state in
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match peek_tt state with
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| Number x ->
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@ -97,7 +97,7 @@ let primary (state : state ref) : expr_result =
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let msg = Printf.sprintf "Expected valid expression, got %s instead" (show_token_type tt) in
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Error { msg; pos }
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let rec grouping (state : state ref) : expr_result =
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let rec grouping (state : state) : expr_result =
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if matches state [| LeftParen |] then (
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advance state;
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let* expr = expression state in
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@ -109,7 +109,7 @@ let rec grouping (state : state ref) : expr_result =
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Error { pos; msg })
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else primary state
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and neg_not (state : state ref) : expr_result =
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and neg_not (state : state) : expr_result =
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if matches state [| Bang; Minus |] then
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let token = next state in
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let pos = token.pos in
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@ -124,7 +124,7 @@ and neg_not (state : state ref) : expr_result =
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Ok expr
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else grouping state
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and mul_or_div (state : state ref) : expr_result =
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and mul_or_div (state : state) : expr_result =
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let* expr = neg_not state in
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let* exprs_tokens = collect_chain state [| Star; Slash |] neg_not in
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let f acc (expr, (token : token)) =
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@ -140,7 +140,7 @@ and mul_or_div (state : state ref) : expr_result =
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let expr = List.fold_left f expr exprs_tokens in
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Ok expr
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and sum_or_diff (state : state ref) : expr_result =
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and sum_or_diff (state : state) : expr_result =
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let* expr = mul_or_div state in
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let* exprs_tokens = collect_chain state [| Plus; Minus |] mul_or_div in
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let f acc (expr, (token : token)) =
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@ -156,7 +156,7 @@ and sum_or_diff (state : state ref) : expr_result =
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let expr = List.fold_left f expr exprs_tokens in
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Ok expr
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and inequality (state : state ref) : expr_result =
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and inequality (state : state) : expr_result =
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(* TODO: maybe rework to only have Less and Greater as ops; performance? *)
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let* expr = sum_or_diff state in
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let* exprs_tokens =
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@ -177,7 +177,7 @@ and inequality (state : state ref) : expr_result =
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let expr = List.fold_left f expr exprs_tokens in
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Ok expr
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and equality (state : state ref) : expr_result =
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and equality (state : state) : expr_result =
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let* expr = inequality state in
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let* exprs_tokens = collect_chain state [| EqualEqual; BangEqual |] inequality in
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let f acc (expr, (token : token)) =
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@ -192,7 +192,7 @@ and equality (state : state ref) : expr_result =
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let expr = List.fold_left f expr exprs_tokens in
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Ok expr
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and logical_and (state : state ref) : expr_result =
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and logical_and (state : state) : expr_result =
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let* expr = equality state in
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let* exprs_tokens = collect_chain state [| And |] equality in
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let f acc (expr, (token : token)) =
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@ -203,7 +203,7 @@ and logical_and (state : state ref) : expr_result =
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let expr = List.fold_left f expr exprs_tokens in
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Ok expr
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and logical_or (state : state ref) : expr_result =
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and logical_or (state : state) : expr_result =
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let* expr = logical_and state in
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let* exprs_tokens = collect_chain state [| Or |] logical_and in
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let f acc (expr, (token : token)) =
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@ -214,7 +214,7 @@ and logical_or (state : state ref) : expr_result =
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let expr = List.fold_left f expr exprs_tokens in
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Ok expr
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and assignment (state : state ref) : expr_result =
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and assignment (state : state) : expr_result =
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let* expr = logical_or state in
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if Equal = peek_tt state then
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let pos = (next state).pos in
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@ -226,9 +226,9 @@ and assignment (state : state ref) : expr_result =
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ParserError.make pos msg |> Result.error
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else Ok expr
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and expression (state : state ref) : expr_result = assignment state
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and expression (state : state) : expr_result = assignment state
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let rec block (state : state ref) : stmt_result =
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let rec block (state : state) : stmt_result =
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let pos = cur_pos state in
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let* _ = consume state LeftBrace in
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let rec collect_stmts state =
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@ -247,7 +247,7 @@ let rec block (state : state ref) : stmt_result =
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let* _ = consume state RightBrace in
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make_block pos stmts |> Result.ok
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and if_then_else (state : state ref) : stmt_result =
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and if_then_else (state : state) : stmt_result =
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let pos = cur_pos state in
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let* _ = consume state If in
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let* _ = consume state LeftParen in
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@ -259,7 +259,7 @@ and if_then_else (state : state ref) : stmt_result =
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in
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make_if pos cond then_ else_ |> Result.ok
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and while_loop (state : state ref) : stmt_result =
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and while_loop (state : state) : stmt_result =
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let pos = cur_pos state in
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let* _ = consume state While in
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let* _ = consume state LeftParen in
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@ -268,7 +268,7 @@ and while_loop (state : state ref) : stmt_result =
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let* body = with_is_in_loop statement state in
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make_while pos cond body |> Result.ok
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and for_loop (state : state ref) : stmt_result =
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and for_loop (state : state) : stmt_result =
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let pos = cur_pos state in
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let* _ = consume state For in
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let* _ = consume state LeftParen in
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@ -296,18 +296,18 @@ and for_loop (state : state ref) : stmt_result =
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let* body = with_is_in_loop statement state in
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make_for pos init cond update body |> Result.ok
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and expr_stmt (state : state ref) : stmt_result =
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and expr_stmt (state : state) : stmt_result =
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let pos = cur_pos state in
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let* expr = expression state in
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let* _ = consume state Semicolon in
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let stmt = make_expr_stmt pos expr in
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Ok stmt
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and statement (state : state ref) : stmt_result =
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and statement (state : state) : stmt_result =
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let pos = cur_pos state in
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match peek_tt state with
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| Break ->
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if !state.is_in_loop then (
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if state.is_in_loop then (
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advance state;
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let* _ = consume state Semicolon in
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make_break pos |> Result.ok)
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@ -315,7 +315,7 @@ and statement (state : state ref) : stmt_result =
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let msg = "Can use break only in loops" in
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ParserError.make pos msg |> Result.error
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| Continue ->
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if !state.is_in_loop then (
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if state.is_in_loop then (
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advance state;
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let* _ = consume state Semicolon in
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make_continue pos |> Result.ok)
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@ -334,7 +334,7 @@ and statement (state : state ref) : stmt_result =
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| For -> for_loop state
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| _ -> expr_stmt state
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and var_declaration (state : state ref) : stmt_result =
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and var_declaration (state : state) : stmt_result =
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let pos = cur_pos state in
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(* consume var token *)
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assert ((next state).token_type = Var);
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@ -351,10 +351,10 @@ and var_declaration (state : state ref) : stmt_result =
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let* _ = consume state Semicolon in
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make_var_decl pos name init |> Result.ok
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and declaration (state : state ref) : stmt_result =
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and declaration (state : state) : stmt_result =
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match peek_tt state with Var -> var_declaration state | _ -> statement state
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let rec synchronise (state : state ref) =
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let rec synchronise (state : state) =
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match peek_tt state with
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| Semicolon -> advance state
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| Class | Fun | Var | For | If | While | Print | Return | Eof -> ()
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@ -362,7 +362,7 @@ let rec synchronise (state : state ref) =
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advance state;
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synchronise state
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let rec parse_impl (state : state ref) : parse_result =
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let rec parse_impl (state : state) : parse_result =
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if peek_tt state = Eof then Ok []
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else
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let result = declaration state in
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