Parse and add frontmatter to page model

Author: panglesd

src/model/comment.ml

@@ -130,15 +130,34 @@ and link_content_of_inline_elements l =
   l |> List.map link_content_of_inline_element |> List.concat
 
 let find_zero_heading docs : link_content option =
-  let rec find_map f = function
-    | [] -> None
-    | x :: l -> (
-        match f x with Some _ as result -> result | None -> find_map f l)
-  in
-  find_map
+  Odoc_utils.List.find_map
     (fun doc ->
       match doc.Location_.value with
       | `Heading ({ heading_level = `Title; _ }, _, h_content) ->
           Some (link_content_of_inline_elements h_content)
       | _ -> None)
     docs
+
+let extract_frontmatter docs : _ =
+  let parse_frontmatter s =
+    let lines = Astring.String.cuts ~sep:"\n" s in
+    Odoc_utils.List.filter_map
+      (fun line -> Astring.String.cut ~sep:":" line)
+      lines
+  in
+  let extracted =
+    let rec aux acc = function
+      | [] -> None
+      | doc :: l -> (
+          match doc.Location_.value with
+          | `Code_block (Some "frontmatter", content, None) ->
+              Some
+                ( parse_frontmatter content.Location_.value,
+                  List.rev_append acc l )
+          | _ -> aux (doc :: acc) l)
+    in
+    aux [] docs
+  in
+  match extracted with
+  | None -> (None, docs)
+  | Some (fm, docs) -> (Some fm, docs)

src/model/dune

@@ -16,4 +16,4 @@
   (backend landmarks --auto))
  (instrumentation
   (backend bisect_ppx))
- (libraries result compiler-libs.common odoc-parser))
+ (libraries result compiler-libs.common odoc-parser odoc_utils))

src/model/lang.ml

@@ -527,11 +527,16 @@ end =
 module rec Page : sig
   type child = Page_child of string | Module_child of string
 
+  module Frontmatter : sig
+    type t = (string * string) list
+  end
+
   type t = {
     name : Identifier.Page.t;
     root : Root.t;
     content : Comment.docs;
     children : child list;
+    frontmatter : Frontmatter.t option;
     digest : Digest.t;
     linked : bool;
   }

src/odoc/compile.ml

@@ -238,12 +238,14 @@ let mld ~parent_id ~parents_children ~output ~children ~warnings_options input =
   >>= fun name ->
   let resolve content =
     let zero_heading = Comment.find_zero_heading content in
+    let frontmatter, content = Comment.extract_frontmatter content in
     let root =
       let file = Root.Odoc_file.create_page root_name zero_heading in
       { Root.id = (name :> Paths.Identifier.OdocId.t); file; digest }
     in
     let page =
-      Lang.Page.{ name; root; children; content; digest; linked = false }
+      Lang.Page.
+        { name; root; children; content; digest; linked = false; frontmatter }
     in
     Odoc_file.save_page output ~warnings:[] page;
     Ok ()

src/odoc/html_fragment.ml

@@ -15,9 +15,18 @@ let from_mld ~xref_base_uri ~resolver ~output ~warnings_options input =
   in
   let to_html content =
     (* This is a mess. *)
+    let frontmatter, content = Odoc_model.Comment.extract_frontmatter content in
     let page =
       Odoc_model.Lang.Page.
-        { name = id; root; content; children = []; digest; linked = false }
+        {
+          name = id;
+          root;
+          content;
+          children = [];
+          digest;
+          linked = false;
+          frontmatter;
+        }
     in
     let env = Resolver.build_env_for_page resolver page in
     Odoc_xref2.Link.resolve_page ~filename:input_s env page