package merlin-lib
Merlin's libraries
Install
Dune Dependency
Authors
Maintainers
Sources
merlin-5.5-503.tbz
sha256=67da3b34f2fea07678267309f61da4a2c6f08298de0dc59655b8d30fd8269af1
sha512=1fb3b5180d36aa82b82a319e15b743b802b6888f0dc67645baafdb4e18dfc23a7b90064ec9bc42f7424061cf8cde7f8839178d8a8537bf4596759f3ff4891873
doc/src/merlin-lib.analysis/signature_help.ml.html
Source file signature_help.ml
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open Std let { Logger.log } = Logger.for_section "signature-help" type parameter_info = { label : Asttypes.arg_label; param_start : int; param_end : int; argument : Typedtree.expression option } type application_signature = { function_name : string option; function_position : Msource.position; signature : string; parameters : parameter_info list; active_param : int option } (* extract a properly parenthesized identifier from (expression_desc (Texp_ident (Longident))) *) let extract_ident (exp_desc : Typedtree.expression_desc) = let rec longident ppf : Longident.t -> unit = function | Lident s -> Format.fprintf ppf "%s" (Misc_utils.parenthesize_name s) | Ldot (p, s) -> Format.fprintf ppf "%a.%s" longident p (Misc_utils.parenthesize_name s) | Lapply (p1, p2) -> Format.fprintf ppf "%a(%a)" longident p1 longident p2 in match exp_desc with | Texp_ident (_, { txt = li; _ }, _) -> let ppf, to_string = Format.to_string () in longident ppf li; Some (to_string ()) | _ -> None (* Type variables shared across arguments should all be printed with the same name. [Printtyp.type_scheme] ensure that a name is unique within a given type, but not across different invocations. [reset] followed by calls to [mark_loops] and [type_sch] provide that *) let pp_type env ppf ty = let module Printtyp = Type_utils.Printtyp in Printtyp.wrap_printing_env env ~verbosity:(Lvl 0) (fun () -> Printtyp.shared_type_scheme ppf ty) let rec type_is_arrow ty = match Types.get_desc ty with | Tarrow _ -> true | Tlink ty -> type_is_arrow ty | Tpoly (ty, _) -> type_is_arrow ty | _ -> false (* surround function types in parentheses *) let pp_parameter_type env ppf ty = if type_is_arrow ty then Format.fprintf ppf "(%a)" (pp_type env) ty else pp_type env ppf ty (* print parameter labels and types *) let pp_parameter env label ppf ty = match (label : Asttypes.arg_label) with | Nolabel -> pp_parameter_type env ppf ty | Labelled l -> Format.fprintf ppf "%s:%a" l (pp_parameter_type env) ty | Optional l -> (* unwrap option for optional labels the same way as [Raw_compat.labels_of_application] *) let unwrap_option ty = match Types.get_desc ty with | Types.Tconstr (path, [ ty ], _) when Path.same path Predef.path_option -> ty | _ -> ty in Format.fprintf ppf "?%s:%a" l (pp_parameter_type env) (unwrap_option ty) (* record buffer offsets to be able to underline parameter types *) let print_parameter_offset ?arg:argument ppf buffer env label ty = let param_start = Buffer.length buffer in Format.fprintf ppf "%a%!" (pp_parameter env label) ty; let param_end = Buffer.length buffer in Format.pp_print_string ppf " -> "; Format.pp_print_flush ppf (); { label; param_start; param_end; argument } (* This function preprocesses the signature and associate already assigned arguments to the corresponding parameter. (They should always be in the correct order in the typedtree, even if they are not in order in the source file.) *) let separate_function_signature ~args (e : Typedtree.expression) = Out_type.reset (); let buffer = Buffer.create 16 in let ppf = Format.formatter_of_buffer buffer in let rec separate ?(parameters = []) args ty = match (args, Types.get_desc ty) with | (_l, arg) :: args, Tarrow (label, ty1, ty2, _) -> let parameter = print_parameter_offset ppf buffer e.exp_env label ty1 ?arg in separate args ty2 ~parameters:(parameter :: parameters) | [], Tarrow (label, ty1, ty2, _) -> let parameter = print_parameter_offset ppf buffer e.exp_env label ty1 in separate args ty2 ~parameters:(parameter :: parameters) (* end of function type, print remaining type without recording offsets *) | _ -> Format.fprintf ppf "%a%!" (pp_type e.exp_env) ty; { function_name = extract_ident e.exp_desc; function_position = `Offset e.exp_loc.loc_end.pos_cnum; signature = Buffer.contents buffer; parameters = List.rev parameters; active_param = None } in separate args e.exp_type let active_parameter_by_arg ~arg params = let find_by_arg = function | { argument = Some a; _ } when a == arg -> true | _ -> false in try Some (List.index params ~f:find_by_arg) with Not_found -> None let first_unassigned_argument params = let positional = function | { argument = None; label = Asttypes.Nolabel; _ } -> true | _ -> false in let labelled = function | { argument = None; label = Asttypes.Labelled _ | Optional _; _ } -> true | _ -> false in try Some (List.index params ~f:positional) with Not_found -> ( try Some (List.index params ~f:labelled) with Not_found -> None) let active_parameter_by_prefix ~prefix params = let common = function | Asttypes.Nolabel -> Some 0 | l when String.is_prefixed ~by:"~" prefix || String.is_prefixed ~by:"?" prefix -> Some (String.common_prefix_len (Btype.prefixed_label_name l) prefix) | _ -> None in let rec find_by_prefix ?(i = 0) ?longest_len ?longest_i = function | [] -> longest_i | p :: ps -> ( match (common p.label, longest_len) with | Some common_len, Some longest_len when common_len > longest_len -> find_by_prefix ps ~i:(succ i) ~longest_len:common_len ~longest_i:i | Some common_len, None -> find_by_prefix ps ~i:(succ i) ~longest_len:common_len ~longest_i:i | _ -> find_by_prefix ps ~i:(succ i) ?longest_len ?longest_i) in find_by_prefix params let is_arrow t = match Types.get_desc t with | Tarrow _ -> true | _ -> false let application_signature ~prefix ~cursor = function | (_, Browse_raw.Expression arg) :: ( _, Expression { exp_desc = Texp_apply (({ exp_type; _ } as e), args); _ } ) :: _ when is_arrow exp_type -> log ~title:"application_signature" "Last arg:\n%a" Logger.fmt (fun fmt -> Printtyped.expression fmt arg); let result = separate_function_signature e ~args in let active_param = if prefix = "" && Lexing.compare_pos cursor arg.exp_loc.loc_end > 0 then begin (* If the cursor is placed after the last arg it means that a whitespace was inserted and we want to underline the next argument. *) log ~title:"application_signature" "Current cursor position is after the last argument"; first_unassigned_argument result.parameters end else (* If not, we identify the argument which is being written *) let active_param = active_parameter_by_arg ~arg result.parameters in match active_param with | Some _ as ap -> ap | None -> active_parameter_by_prefix ~prefix result.parameters in Some { result with active_param } | (_, Expression ({ exp_type; _ } as e)) :: _ when is_arrow exp_type -> (* provide signature information directly after an unapplied function-type value *) let result = separate_function_signature e ~args:[] in let active_param = active_parameter_by_prefix ~prefix result.parameters in Some { result with active_param } | _ -> None let prefix_of_position ~short_path source position = match Msource.text source with | "" -> "" | text -> let from = let (`Offset index) = Msource.get_offset source position in min (String.length text - 1) (index - 1) in let pos = let should_terminate = ref false in let has_seen_dot = ref false in let is_prefix_char c = if !should_terminate then false else match c with | 'a' .. 'z' | 'A' .. 'Z' | '0' .. '9' | '\'' | '_' (* Infix function characters *) | '$' | '&' | '*' | '+' | '-' | '/' | '=' | '>' | '@' | '^' | '!' | '?' | '%' | '<' | ':' | '~' | '#' -> true | '`' -> if !has_seen_dot then false else ( should_terminate := true; true) | '.' -> has_seen_dot := true; not short_path | _ -> false in String.rfindi text ~from ~f:(fun c -> not (is_prefix_char c)) in let pos = match pos with | None -> 0 | Some pos -> pos + 1 in let len = from - pos + 1 in let reconstructed_prefix = String.sub text ~pos ~len in (* if we reconstructed [~f:ignore] or [?f:ignore], we should take only [ignore], so: *) log ~title:"prefix_of_position" "%S" reconstructed_prefix; if String.is_prefix reconstructed_prefix ~prefix:"~" || String.is_prefix reconstructed_prefix ~prefix:"?" then match String.lsplit2 reconstructed_prefix ~on:':' with | Some (_, s) -> s | None -> reconstructed_prefix else reconstructed_prefix
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