inshellah/lib/store.ml
2026-03-29 19:28:20 +11:00

670 lines
28 KiB
OCaml

(* store.ml — filesystem-backed cache of parsed completion data.
*
* this module handles persistence of completion data to disk. each command's
* help_result is serialized to JSON and stored as a file in a cache directory
* (default: $XDG_CACHE_HOME/inshellah). commands with native nushell completions
* are stored as .nu files instead.
*
* the store also provides lookup, listing, and subcommand discovery by
* scanning filenames in the cache directory.
*
* file naming convention:
* - spaces in command names become underscores (e.g. "git add" -> "git_add.json")
* - subcommands of a parent share the prefix (e.g. "git_add.json", "git_commit.json")
* - .json files contain serialized help_result
* - .nu files contain native nushell extern source code
*
* the module includes a minimal hand-rolled JSON parser/serializer because
* we only need to handle our own output format (no need for a full JSON library).
*)
open Parser
(* get the default store path: $XDG_CACHE_HOME/inshellah, falling back to
* ~/.cache/inshellah if XDG_CACHE_HOME is not set. *)
let default_store_path () =
let cache = try Sys.getenv "XDG_CACHE_HOME"
with Not_found -> Filename.concat (Sys.getenv "HOME") ".cache" in
Filename.concat cache "inshellah"
(* recursively create directories along a path (equivalent to mkdir -p).
* splits the path into components and folds over them, accumulating
* the current directory prefix and creating each level if missing. *)
let ensure_dir dir =
let sep = Filename.dir_sep in
let parts = String.split_on_char sep.[0] dir in
(* determine the starting prefix: absolute paths begin with "/" *)
let start = if String.length dir > 0 && dir.[0] = sep.[0] then sep else "" in
let _final =
List.fold_left (fun current part ->
if part = "" then current
else begin
let next = if current = sep then sep ^ part
else if current = "" then part
else current ^ sep ^ part in
(if not (Sys.file_exists next) then Unix.mkdir next 0o755);
next
end
) start parts
in
()
(* convert command name to safe filename: spaces become underscores,
* non-alphanumeric chars become hyphens.
* e.g. "git add" -> "git_add", "docker-compose" -> "docker-compose" *)
let filename_of_command cmd =
String.map (function
| ' ' -> '_'
| ('a'..'z' | 'A'..'Z' | '0'..'9' | '-' | '_' | '.') as char_val -> char_val
| _ -> '-') cmd
(* inverse of filename_of_command: underscores back to spaces.
* note: this is lossy — original underscores in command names
* (e.g. "my_tool") would be converted to spaces. in practice this
* doesn't matter because tools with underscores in names are rare,
* and subcommands use space-separated naming. *)
let command_of_filename base_name =
String.map (function '_' -> ' ' | char_val -> char_val) base_name
(* --- JSON serialization of help_result ---
* hand-rolled JSON emitters. we don't use a JSON library because:
* 1. the schema is fixed and simple — we only serialize our own types
* 2. avoiding dependencies keeps the binary small
* 3. printf-style emission is fast and straightforward for our types *)
(* escape a string for JSON: quotes, backslashes, and control characters.
* control chars below 0x20 are emitted as \uXXXX unicode escapes. *)
let escape_json contents =
let buf = Buffer.create (String.length contents + 4) in
String.iter (fun char_val -> match char_val with
| '"' -> Buffer.add_string buf "\\\""
| '\\' -> Buffer.add_string buf "\\\\"
| '\n' -> Buffer.add_string buf "\\n"
| '\t' -> Buffer.add_string buf "\\t"
| '\r' -> Buffer.add_string buf "\\r"
| c when Char.code c < 0x20 ->
Buffer.add_string buf (Printf.sprintf "\\u%04x" (Char.code c))
| c -> Buffer.add_char buf c
) contents;
Buffer.contents buf
(* wrap a string in quotes after escaping for JSON *)
let json_string text = Printf.sprintf "\"%s\"" (escape_json text)
(* the literal null value for JSON output *)
let json_null = "null"
(* serialize a switch (short flag, long flag, or both) to JSON *)
let json_switch_of = function
| Short char_val ->
Printf.sprintf "{\"type\":\"short\",\"char\":%s}" (json_string (String.make 1 char_val))
| Long name ->
Printf.sprintf "{\"type\":\"long\",\"name\":%s}" (json_string name)
| Both (char_val, name) ->
Printf.sprintf "{\"type\":\"both\",\"char\":%s,\"name\":%s}"
(json_string (String.make 1 char_val)) (json_string name)
(* serialize a parameter spec (mandatory, optional, or absent) to JSON *)
let json_param_of = function
| None -> json_null
| Some (Mandatory name) ->
Printf.sprintf "{\"kind\":\"mandatory\",\"name\":%s}" (json_string name)
| Some (Optional name) ->
Printf.sprintf "{\"kind\":\"optional\",\"name\":%s}" (json_string name)
(* serialize a single flag entry (switch + param + description) to JSON *)
let json_entry_of entry =
Printf.sprintf "{\"switch\":%s,\"param\":%s,\"desc\":%s}"
(json_switch_of entry.switch) (json_param_of entry.param) (json_string entry.desc)
(* serialize a subcommand (name + description) to JSON *)
let json_subcommand_of sc =
Printf.sprintf "{\"name\":%s,\"desc\":%s}" (json_string sc.name) (json_string sc.desc)
(* serialize a positional argument to JSON *)
let json_positional_of p =
Printf.sprintf "{\"name\":%s,\"optional\":%b,\"variadic\":%b}"
(json_string p.pos_name) p.optional p.variadic
(* serialize a list of items to a JSON array using the given formatter *)
let json_list formatter items =
"[" ^ String.concat "," (List.map formatter items) ^ "]"
(* serialize an entire help_result to a JSON object string *)
let json_of_help_result ?(source="help") result =
Printf.sprintf "{\"source\":%s,\"description\":%s,\"entries\":%s,\"subcommands\":%s,\"positionals\":%s}"
(json_string source)
(json_string result.description)
(json_list json_entry_of result.entries)
(json_list json_subcommand_of result.subcommands)
(json_list json_positional_of result.positionals)
(* --- JSON deserialization ---
* minimal hand-rolled recursive-descent JSON parser. only handles the subset
* we emit: strings, booleans, nulls, arrays, and objects. no number parsing
* (we don't emit numbers). this is intentionally minimal — we only read back
* our own serialized format, so robustness against arbitrary JSON is not needed.
*
* note: the \u escape handler does basic UTF-8 encoding for code points
* up to 0xFFFF but doesn't handle surrogate pairs. this is fine for our use
* case since we only escape control characters below 0x20. *)
type json =
| Jnull
| Jbool of bool
| Jstring of string
| Jarray of json list
| Jobject of (string * json) list
(* JSON accessor helpers — return sensible defaults for missing/wrong types *)
let json_get key = function
| Jobject pairs -> (try List.assoc key pairs with Not_found -> Jnull)
| _ -> Jnull
(* extract a string from a JSON value, defaulting to empty string *)
let json_to_string = function Jstring text -> text | _ -> ""
(* extract a boolean from a JSON value, defaulting to false *)
let json_to_bool = function Jbool value -> value | _ -> false
(* extract a list from a JSON array value, defaulting to empty list *)
let json_to_list = function Jarray items -> items | _ -> []
exception Json_error of string
(* imperative recursive-descent JSON parser.
* uses a mutable position ref to walk through the string.
* note: boolean/null parsing just advances a fixed number of chars
* without validating the actual characters — safe because we only read
* our own output, but would be incorrect for arbitrary JSON. *)
let parse_json contents =
let len = String.length contents in
let pos = ref 0 in
(* peek at the current character without consuming it *)
let peek () = if !pos < len then contents.[!pos] else '\x00' in
(* advance the position by one character *)
let advance () = incr pos in
(* skip over any whitespace characters at current position *)
let skip_ws () =
while !pos < len && (contents.[!pos] = ' ' || contents.[!pos] = '\t'
|| contents.[!pos] = '\n' || contents.[!pos] = '\r') do
advance ()
done in
(* skip whitespace then consume the expected character, or raise *)
let expect char_val =
skip_ws ();
if peek () <> char_val then
raise (Json_error (Printf.sprintf "expected '%c' at %d" char_val !pos));
advance () in
(* mutually recursive parsers for each JSON value type *)
let rec parse_value () =
skip_ws ();
match peek () with
| '"' -> Jstring (parse_string ())
| '{' -> parse_object ()
| '[' -> parse_array ()
| 'n' -> advance (); advance (); advance (); advance (); Jnull
| 't' -> advance (); advance (); advance (); advance (); Jbool true
| 'f' ->
advance (); advance (); advance (); advance (); advance (); Jbool false
| char_val ->
raise (Json_error (Printf.sprintf "unexpected '%c' at %d" char_val !pos))
(* parse a quoted string value, handling escape sequences *)
and parse_string () =
expect '"';
let buf = Buffer.create 32 in
while peek () <> '"' do
if peek () = '\\' then begin
advance ();
(match peek () with
| '"' -> Buffer.add_char buf '"'
| '\\' -> Buffer.add_char buf '\\'
| 'n' -> Buffer.add_char buf '\n'
| 't' -> Buffer.add_char buf '\t'
| 'r' -> Buffer.add_char buf '\r'
| 'u' ->
(* handle \uXXXX unicode escapes with basic UTF-8 encoding *)
advance ();
let hex = String.sub contents !pos 4 in
pos := !pos + 3;
let code = int_of_string ("0x" ^ hex) in
if code < 128 then Buffer.add_char buf (Char.chr code)
else begin
if code < 0x800 then begin
Buffer.add_char buf (Char.chr (0xc0 lor (code lsr 6)));
Buffer.add_char buf (Char.chr (0x80 lor (code land 0x3f)))
end else begin
Buffer.add_char buf (Char.chr (0xe0 lor (code lsr 12)));
Buffer.add_char buf (Char.chr (0x80 lor ((code lsr 6) land 0x3f)));
Buffer.add_char buf (Char.chr (0x80 lor (code land 0x3f)))
end
end
| char_val -> Buffer.add_char buf char_val);
advance ()
end else begin
Buffer.add_char buf (peek ());
advance ()
end
done;
advance (); (* consume closing quote *)
Buffer.contents buf
(* parse a JSON object: { "key": value, ... } *)
and parse_object () =
expect '{';
skip_ws ();
if peek () = '}' then (advance (); Jobject [])
else begin
let pairs = ref [] in
let more = ref true in
while !more do
skip_ws ();
let key = parse_string () in
expect ':';
let value = parse_value () in
pairs := (key, value) :: !pairs;
skip_ws ();
if peek () = ',' then advance ()
else more := false
done;
expect '}';
Jobject (List.rev !pairs)
end
(* parse a JSON array: [ value, value, ... ] *)
and parse_array () =
expect '[';
skip_ws ();
if peek () = ']' then (advance (); Jarray [])
else begin
let items = ref [] in
let more = ref true in
while !more do
let value = parse_value () in
items := value :: !items;
skip_ws ();
if peek () = ',' then advance ()
else more := false
done;
expect ']';
Jarray (List.rev !items)
end
in
parse_value ()
(* --- JSON to OCaml type converters ---
* these reconstruct our parser types from their JSON representations.
* they mirror the json_*_of serializers above. *)
(* reconstruct a switch value from its JSON representation *)
let switch_of_json json_node =
match json_to_string (json_get "type" json_node) with
| "short" ->
let char_str = json_to_string (json_get "char" json_node) in
Short (if String.length char_str > 0 then char_str.[0] else '?')
| "long" -> Long (json_to_string (json_get "name" json_node))
| "both" ->
let char_str = json_to_string (json_get "char" json_node) in
Both ((if String.length char_str > 0 then char_str.[0] else '?'),
json_to_string (json_get "name" json_node))
| _ -> Long "?"
(* reconstruct a parameter spec from its JSON representation *)
let param_of_json = function
| Jnull -> None
| json_node ->
let name = json_to_string (json_get "name" json_node) in
(match json_to_string (json_get "kind" json_node) with
| "mandatory" -> Some (Mandatory name)
| "optional" -> Some (Optional name)
| _ -> None)
(* reconstruct a flag entry from its JSON representation *)
let entry_of_json json_node =
{ switch = switch_of_json (json_get "switch" json_node);
param = param_of_json (json_get "param" json_node);
desc = json_to_string (json_get "desc" json_node) }
(* reconstruct a subcommand from its JSON representation *)
let subcommand_of_json json_node =
{ name = json_to_string (json_get "name" json_node);
desc = json_to_string (json_get "desc" json_node) }
(* reconstruct a positional argument from its JSON representation *)
let positional_of_json json_node =
{ pos_name = json_to_string (json_get "name" json_node);
optional = json_to_bool (json_get "optional" json_node);
variadic = json_to_bool (json_get "variadic" json_node) }
(* reconstruct a full help_result from its JSON representation *)
let help_result_of_json json_node =
{ entries = List.map entry_of_json (json_to_list (json_get "entries" json_node));
subcommands = List.map subcommand_of_json (json_to_list (json_get "subcommands" json_node));
positionals = List.map positional_of_json (json_to_list (json_get "positionals" json_node));
description = json_to_string (json_get "description" json_node) }
(* --- filesystem operations --- *)
(* write a string to a file, overwriting any existing content *)
let write_file path contents =
let oc = open_out path in
output_string oc contents;
close_out oc
(* read an entire file into a string, returning None on any error *)
let read_file path =
try
let ic = open_in path in
let size = in_channel_length ic in
let contents = Bytes.create size in
really_input ic contents 0 size;
close_in ic;
Some (Bytes.to_string contents)
with _ -> None
(* write a parsed help_result to the store as JSON *)
let write_result ~dir ?(source="help") command result =
let path = Filename.concat dir (filename_of_command command ^ ".json") in
write_file path (json_of_help_result ~source result)
(* write native nushell completion source to the store as a .nu file *)
let write_native ~dir command data =
let path = Filename.concat dir (filename_of_command command ^ ".nu") in
write_file path data
(* check whether a path exists and is a directory *)
let is_dir path = Sys.file_exists path && Sys.is_directory path
(* look for a command's data file across multiple store directories.
* checks JSON first, then .nu. returns the first match found.
* directories are searched in order (user dir before system dirs). *)
let find_file dirs command =
let base_name = filename_of_command command in
List.find_map (fun directory ->
let json_path = Filename.concat directory (base_name ^ ".json") in
if Sys.file_exists json_path then Some json_path
else
let nu_path = Filename.concat directory (base_name ^ ".nu") in
if Sys.file_exists nu_path then Some nu_path
else None
) dirs
(* parse a nushell .nu file to extract a help_result for a specific command.
* .nu files contain `export extern "cmd" [ ... ]` blocks with flag definitions.
* this parser extracts flags, positionals, subcommands, and descriptions
* from the nushell extern syntax so the completer can use native completions.
*
* nushell extern parameter syntax:
* --flag(-s): type # description → Both(s, "flag") with param
* --flag: type # description → Long "flag" with param
* --flag # description → Long "flag" no param
* -s # description → Short 's'
* name: type # description → positional
* name?: type → optional positional
* ...name: type → variadic positional
*)
let parse_nu_completions target_cmd contents =
let lines = String.split_on_char '\n' contents in
(* extract the description comment preceding an export extern block *)
let current_desc = ref "" in
(* collect all extern blocks: (cmd_name, entries, positionals, description) *)
let blocks = ref [] in
let in_block = ref false in
let block_cmd = ref "" in
let block_entries = ref [] in
let block_positionals = ref [] in
let block_desc = ref "" in
let finish_block () =
if !in_block then begin
blocks := (!block_cmd, List.rev !block_entries,
List.rev !block_positionals, !block_desc) :: !blocks;
in_block := false
end in
List.iter (fun line ->
let trimmed = String.trim line in
if not !in_block then begin
(* look for description comments and export extern lines *)
if String.length trimmed > 2 && trimmed.[0] = '#' && trimmed.[1] = ' ' then
current_desc := String.trim (String.sub trimmed 2 (String.length trimmed - 2))
else if String.length trimmed > 15
&& (try ignore (Str.search_forward
(Str.regexp_string "export extern") trimmed 0); true
with Not_found -> false) then begin
(* extract command name from: export extern "cmd name" [ or export extern cmd [ *)
let re_quoted = Str.regexp {|export extern "\([^"]*\)"|} in
let re_bare = Str.regexp {|export extern \([a-zA-Z0-9_-]+\)|} in
let cmd_opt =
if try ignore (Str.search_forward re_quoted trimmed 0); true
with Not_found -> false
then Some (Str.matched_group 1 trimmed)
else if try ignore (Str.search_forward re_bare trimmed 0); true
with Not_found -> false
then Some (Str.matched_group 1 trimmed)
else None in
if cmd_opt <> None then begin
let cmd = match cmd_opt with Some c -> c | None -> "" in
in_block := true;
block_cmd := cmd;
block_entries := [];
block_positionals := [];
block_desc := !current_desc;
current_desc := ""
end
end else
current_desc := ""
end else begin
(* inside an extern block — parse flag/positional lines *)
if String.length trimmed > 0 && trimmed.[0] = ']' then
finish_block ()
else begin
(* extract description from # comment *)
let param_part, desc =
match String.split_on_char '#' trimmed with
| before :: rest ->
(String.trim before,
String.trim (String.concat "#" rest))
| _ -> (trimmed, "")
in
if String.length param_part > 1 then begin
if param_part.[0] = '-' && param_part.[1] = '-' then begin
(* long flag: --flag(-s): type or --flag: type or --flag *)
let re_both = Str.regexp {|--\([a-zA-Z0-9-]+\)(-\([a-zA-Z0-9]\))\(: *\([a-zA-Z]+\)\)?|} in
let re_long = Str.regexp {|--\([a-zA-Z0-9-]+\)\(: *\([a-zA-Z]+\)\)?|} in
if try ignore (Str.search_forward re_both param_part 0); true
with Not_found -> false then begin
let long = Str.matched_group 1 param_part in
let short = (Str.matched_group 2 param_part).[0] in
let param = try Some (Mandatory (Str.matched_group 4 param_part))
with Not_found | Invalid_argument _ -> None in
block_entries := { switch = Both (short, long); param; desc } :: !block_entries
end else if try ignore (Str.search_forward re_long param_part 0); true
with Not_found -> false then begin
let long = Str.matched_group 1 param_part in
let param = try Some (Mandatory (Str.matched_group 3 param_part))
with Not_found | Invalid_argument _ -> None in
block_entries := { switch = Long long; param; desc } :: !block_entries
end
end else if param_part.[0] = '-' then begin
(* short flag: -s *)
if String.length param_part >= 2 then
let c = param_part.[1] in
if (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') then
block_entries := { switch = Short c; param = None; desc } :: !block_entries
end else begin
(* positional: name: type or name?: type or ...name: type *)
let variadic = String.starts_with ~prefix:"..." param_part in
let part = if variadic then String.sub param_part 3 (String.length param_part - 3)
else param_part in
let optional = try let q = String.index part '?' in q > 0
with Not_found -> false in
let name = match String.index_opt part ':' with
| Some i -> String.trim (String.sub part 0 i)
| None -> match String.index_opt part '?' with
| Some i -> String.trim (String.sub part 0 i)
| None -> String.trim part in
let name = String.map (function '-' -> '_' | c -> c) name in
if String.length name > 0 && name.[0] <> '-' then
block_positionals := { pos_name = name; optional = optional || variadic;
variadic } :: !block_positionals
end
end
end
end
) lines;
finish_block ();
let blocks = List.rev !blocks in
(* find the block matching the target command *)
let target = target_cmd in
match List.find_opt (fun (cmd, _, _, _) -> cmd = target) blocks with
| Some (_, entries, positionals, description) ->
(* collect subcommands from other blocks that are children of this command *)
let prefix = target ^ " " in
let subcommands = List.filter_map (fun (cmd, _, _, desc) ->
if String.starts_with ~prefix cmd then
let sub_name = String.sub cmd (String.length prefix)
(String.length cmd - String.length prefix) in
(* only immediate subcommands (no further spaces) *)
if not (String.contains sub_name ' ') && String.length sub_name > 0
then Some { name = sub_name; desc }
else None
else None
) blocks in
{ entries; subcommands; positionals; description }
| None ->
(* target not found — return empty result *)
{ entries = []; subcommands = []; positionals = []; description = "" }
(* look up a command and deserialize its help_result.
* searches for .json files first, then falls back to .nu files
* (parsing the nushell extern syntax to extract completion data).
* for subcommands like "rbw get", also checks the parent's .nu file
* (e.g. rbw.nu) since clap-generated .nu files contain all extern
* blocks in a single file. *)
let lookup dirs command =
let base_name = filename_of_command command in
(* also try the root command's .nu file for subcommand lookups.
* "rbw get" -> try rbw.nu and look for the "rbw get" extern block. *)
let parent_base = match String.index_opt command ' ' with
| Some i -> Some (filename_of_command (String.sub command 0 i))
| None -> None in
List.find_map (fun directory ->
let json_path = Filename.concat directory (base_name ^ ".json") in
match read_file json_path with
| Some data ->
(try Some (help_result_of_json (parse_json data))
with _ -> None)
| None ->
let nu_path = Filename.concat directory (base_name ^ ".nu") in
(match read_file nu_path with
| Some data ->
(try Some (parse_nu_completions command data)
with _ -> None)
| None ->
(* try parent's .nu file for subcommand blocks *)
match parent_base with
| Some pb ->
let parent_nu = Filename.concat directory (pb ^ ".nu") in
(match read_file parent_nu with
| Some data ->
(try
let r = parse_nu_completions command data in
if r.entries <> [] || r.subcommands <> [] || r.positionals <> []
then Some r else None
with _ -> None)
| None -> None)
| None -> None)
) dirs
(* look up a command's raw data (JSON or .nu source) without parsing.
* used by the "query" command to dump stored data as-is. *)
let lookup_raw dirs command =
let base_name = filename_of_command command in
List.find_map (fun directory ->
let json_path = Filename.concat directory (base_name ^ ".json") in
match read_file json_path with
| Some _ as result -> result
| None ->
let nu_path = Filename.concat directory (base_name ^ ".nu") in
read_file nu_path
) dirs
(* strip known extensions (.json or .nu) from a filename, returning None
* if the filename has neither extension *)
let chop_extension filename =
if Filename.check_suffix filename ".json" then Some (Filename.chop_suffix filename ".json")
else if Filename.check_suffix filename ".nu" then Some (Filename.chop_suffix filename ".nu")
else None
(* discover subcommands of a command by scanning filenames in the store.
* looks for files whose names start with the command's filename + "_"
* (e.g. for "git", finds "git_add.json", "git_commit.json", etc.)
*
* only returns immediate subcommands (no nested underscores beyond the prefix).
* tries to extract description from the JSON "description" field if available.
*
* note: this filesystem-based discovery is used as a fallback when the
* command's own help_result doesn't list subcommands. it enables completion
* for subcommands that were indexed from separate manpages or help runs. *)
let subcommands_of dirs command =
let prefix = filename_of_command command ^ "_" in
let prefix_len = String.length prefix in
let module SMap = Map.Make(String) in
let subs = List.fold_left (fun subs directory ->
if is_dir directory then
Array.fold_left (fun subs filename ->
if not (String.starts_with ~prefix filename) then subs
else
let is_json = Filename.check_suffix filename ".json" in
match chop_extension filename with
| None -> subs
| Some base_name ->
let rest = String.sub base_name prefix_len (String.length base_name - prefix_len) in
(* skip nested subcommands and empty names *)
if String.contains rest '_' || String.length rest = 0 then subs
else if SMap.mem rest subs then subs
else
(* try to read the description from the JSON file *)
let desc = if is_json then
match read_file (Filename.concat directory filename) with
| Some data ->
(try json_to_string (json_get "description" (parse_json data))
with _ -> "")
| None -> ""
else "" in
SMap.add rest { name = rest; desc } subs
) subs (Sys.readdir directory)
else subs
) SMap.empty dirs in
SMap.fold (fun _ sc acc -> sc :: acc) subs [] |> List.rev
(* list all indexed commands across all store directories.
* returns a sorted, deduplicated list of command names. *)
let all_commands dirs =
let module SSet = Set.Make(String) in
List.fold_left (fun cmds directory ->
if is_dir directory then
Array.fold_left (fun cmds filename ->
match chop_extension filename with
| Some base_name -> SSet.add (command_of_filename base_name) cmds
| None -> cmds
) cmds (Sys.readdir directory)
else cmds
) SSet.empty dirs
|> SSet.elements
(* determine how a command was indexed: "help", "manpage", "native", etc.
* for JSON files, reads the "source" field. for .nu files, returns "native".
* used by the "dump" command to show provenance. *)
let file_type_of dirs command =
let base_name = filename_of_command command in
List.find_map (fun directory ->
let json_path = Filename.concat directory (base_name ^ ".json") in
if Sys.file_exists json_path then
(match read_file json_path with
| Some data ->
(try Some (json_to_string (json_get "source" (parse_json data)))
with _ -> Some "json")
| None -> Some "json")
else
let nu_path = Filename.concat directory (base_name ^ ".nu") in
if Sys.file_exists nu_path then Some "native"
else None
) dirs