71 lines
2.5 KiB
OCaml
71 lines
2.5 KiB
OCaml
module Y = Hl_yaml.Unix
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module StringMap = Map.Make (String)
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exception Frontmatter_parse_error of string
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(* Type for frontmatter data *)
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type t = Yojson.Safe.t StringMap.t
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(* Extract YAML frontmatter from markdown content *)
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let extract_frontmatter (content : string) : string * string =
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let content = String.trim content in
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let len = String.length content in
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(* Check if content starts with --- *)
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if len < 6 || not (String.starts_with ~prefix:"---" content) then ("", content)
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else
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(* Find the end of the first line (after opening ---) *)
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match String.index_from_opt content 3 '\n' with
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| None -> ("", content) (* No newline after opening --- *)
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| Some first_newline -> (
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let yaml_start = first_newline + 1 in
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if yaml_start >= len then ("", content)
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else
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let yaml_section = String.sub content yaml_start (len - yaml_start) in
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(* Find the closing --- at the start of a line *)
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let closing_pos_opt =
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try
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Some
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(Str.search_forward (Str.regexp "^---[ \t]*$") yaml_section 0)
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with Not_found -> None
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in
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match closing_pos_opt with
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| None -> ("", content)
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| Some closing_pos ->
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let yaml_content = String.sub yaml_section 0 closing_pos in
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(* Find content after the closing --- *)
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let after_closing = yaml_start + closing_pos in
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let remaining_content =
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match String.index_from_opt content after_closing '\n' with
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| None -> ""
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| Some next_line ->
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let content_start = next_line + 1 in
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if content_start >= len then ""
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else String.sub content content_start (len - content_start)
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in
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(String.trim yaml_content, String.trim remaining_content))
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(* Convert Yojson object to StringMap *)
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let yojson_to_string_map = function
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| `Assoc assoc ->
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Ok
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(List.fold_left
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(fun acc (key, value) -> StringMap.add key value acc)
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StringMap.empty assoc)
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| _ -> Error "Frontmatter must be a YAML object/map"
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let parse_frontmatter (yaml_content : string) : t =
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if String.trim yaml_content = "" then StringMap.empty
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else
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try
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let options = Y.make_options ~enable_imports:false () in
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let result =
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Y.parse ~options ~of_yojson:yojson_to_string_map yaml_content
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in
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Y.ok_or_raise result
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with exn ->
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raise
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(Frontmatter_parse_error ("Parsing failed: " ^ Printexc.to_string exn))
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