80 lines
3.1 KiB
OCaml
80 lines
3.1 KiB
OCaml
module StringSet = Set.Make (String)
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let starts_with ~prefix s =
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let lp = String.length prefix in
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String.length s >= lp && String.sub s 0 lp = prefix
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let trim = String.trim
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let parse_import_line line =
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let t = trim line in
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if not (starts_with ~prefix:"import" t) then None
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else
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let rest = trim (String.sub t 6 (String.length t - 6)) in
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if String.length rest < 2 || rest.[0] <> '"' then
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Some (Error ("malformed import: " ^ line))
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else
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try
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let q2 = String.index_from rest 1 '"' in
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let path = String.sub rest 1 (q2 - 1) in
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let tail = trim (String.sub rest (q2 + 1) (String.length rest - q2 - 1)) in
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let valid_tail =
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String.equal tail ";"
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|| String.equal tail ""
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|| (starts_with ~prefix:";" tail && starts_with ~prefix:"//" (trim (String.sub tail 1 (String.length tail - 1))))
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in
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if not valid_tail then Some (Error ("malformed import terminator: " ^ line)) else Some (Ok path)
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with Not_found -> Some (Error ("unterminated import string: " ^ line))
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let read_file path =
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let ic = open_in_bin path in
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Fun.protect
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~finally:(fun () -> close_in ic)
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(fun () -> really_input_string ic (in_channel_length ic))
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let resolve_path ~from_dir p = if Filename.is_relative p then Filename.concat from_dir p else p
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let load_source_with_imports entry_path =
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let rec load_file stack visited path =
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if List.mem path stack then
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Error ("import cycle detected at: " ^ path)
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else if StringSet.mem path visited then Ok (visited, "")
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else
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let content =
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try Ok (read_file path) with Sys_error msg -> Error ("cannot read " ^ path ^ ": " ^ msg)
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in
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match content with
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| Error _ as e -> e
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| Ok content ->
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let dir = Filename.dirname path in
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let lines = String.split_on_char '\n' content in
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let rec scan imports body = function
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| [] -> Ok (List.rev imports, List.rev body)
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| ln :: tl ->
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(match parse_import_line ln with
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| None -> scan imports (ln :: body) tl
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| Some (Ok p) -> scan (p :: imports) body tl
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| Some (Error e) -> Error e)
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in
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(match scan [] [] lines with
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| Error _ as e -> e
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| Ok (imports, body_lines) ->
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let rec load_imports vis acc = function
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| [] -> Ok (vis, List.rev acc)
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| imp :: tl ->
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let resolved = resolve_path ~from_dir:dir imp in
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(match load_file (path :: stack) vis resolved with
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| Error _ as e -> e
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| Ok (vis', src) -> load_imports vis' (src :: acc) tl)
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in
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match load_imports visited [] imports with
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| Error _ as e -> e
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| Ok (visited', imported_sources) ->
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let self_src = String.concat "\n" body_lines in
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let full = String.concat "\n" (imported_sources @ [ self_src ]) in
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Ok (StringSet.add path visited', full))
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in
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match load_file [] StringSet.empty entry_path with
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| Error _ as e -> e
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| Ok (_, src) -> Ok src
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