Allow listing outside URLs in extras

This makes it possible to delcare URLs as extras and have them listed as
links in the sidebar. For example, to set a "Wikipedia" url:

```elixir
extras: [
  "Wikipedia": [url: "https://wikipedia.com"]
]
```

Closes #2084

Author: sorentwo

assets/js/sidebar/sidebar-list.js

@@ -59,6 +59,7 @@ export function initialize () {
       const items = []
       const hasHeaders = Array.isArray(node.headers)
       const translate = hasHeaders ? undefined : 'no'
+      const href = node?.url || `${node.id}.html`
 
       // Group header.
       if (node.group !== group) {
@@ -78,7 +79,7 @@ export function initialize () {
       }
 
       items.push(el('li', {}, [
-        el('a', {href: `${node.id}.html`, translate}, [node.nested_title || node.title]),
+        el('a', {href: href, translate}, [node.nested_title || node.title]),
         ...childList(`node-${node.id}-headers`,
           hasHeaders
             ? renderHeaders(node)

formatters/html/dist/html-5PS32TPG.js formatters/html/dist/html-AG646WP7.js

@@ -65,6 +65,9 @@ defmodule ExDoc.Formatter.HTML do
     %{config | main: main || @main}
   end
 
+  defp normalize_extras(base) when is_binary(base), do: {base, %{}}
+  defp normalize_extras({base, opts}), do: {base, Map.new(opts)}
+
   @doc """
   Autolinks and renders all docs.
   """
@@ -209,6 +212,7 @@ defmodule ExDoc.Formatter.HTML do
   defp generate_extras(extras, config) do
     generated_extras =
       extras
+      |> Enum.reject(&is_map_key(&1, :url))
       |> with_prev_next()
       |> Enum.map(fn {node, prev, next} ->
         filename = "#{node.id}.html"
@@ -349,6 +353,7 @@ defmodule ExDoc.Formatter.HTML do
 
     extras =
       config.extras
+      |> Enum.map(&normalize_extras/1)
       |> Task.async_stream(
         &build_extra(&1, groups, language, autolink_opts, source_url_pattern),
         timeout: :infinity
@@ -388,6 +393,24 @@ defmodule ExDoc.Formatter.HTML do
     Map.put(extra, :id, "#{extra.id}-#{discriminator}")
   end
 
+  defp build_extra({input, %{url: _} = input_options}, groups, _lang, _auto, _url_pattern) do
+    input = to_string(input)
+    title = input_options[:title] || filename_to_title(input)
+    group = GroupMatcher.match_extra(groups, input)
+
+    # TODO: Can we make the content/source a link?
+
+    %{
+      group: group,
+      id: Utils.text_to_id(title),
+      source_path: input_options[:url],
+      source_url: input_options[:url],
+      title: title,
+      title_content: title,
+      url: input_options[:url]
+    }
+  end
+
   defp build_extra({input, input_options}, groups, language, autolink_opts, source_url_pattern) do
     input = to_string(input)
     id = input_options[:filename] || input |> filename_to_title() |> Utils.text_to_id()
@@ -447,10 +470,6 @@ defmodule ExDoc.Formatter.HTML do
     }
   end
 
-  defp build_extra(input, groups, language, autolink_opts, source_url_pattern) do
-    build_extra({input, []}, groups, language, autolink_opts, source_url_pattern)
-  end
-
   defp normalize_search_data!(nil), do: nil
 
   defp normalize_search_data!(search_data) when is_list(search_data) do
@@ -602,7 +621,15 @@ defmodule ExDoc.Formatter.HTML do
 
       {path, opts} ->
         base = path |> to_string() |> Path.basename()
-        {base, opts[:filename] || Utils.text_to_id(Path.rootname(base))}
+
+        txid =
+          cond do
+            filename = opts[:filename] -> filename
+            url = opts[:url] -> url
+            true -> Utils.text_to_id(Path.rootname(base))
+          end
+
+        {base, txid}
     end)
   end
 end

lib/ex_doc/formatter/html.ex

@@ -18,36 +18,8 @@ defmodule ExDoc.Formatter.HTML.SearchData do
     ["searchData=" | ExDoc.Utils.to_json(data)]
   end
 
-  defp extra(map) do
-    if custom_search_data = map[:search_data] do
-      extra_search_data(map, custom_search_data)
-    else
-      {intro, sections} = extract_sections_from_markdown(map.source)
-
-      intro_json_item =
-        encode(
-          "#{map.id}.html",
-          map.title,
-          :extras,
-          intro
-        )
-
-      section_json_items =
-        for {header, body} <- sections do
-          encode(
-            "#{map.id}.html##{Utils.text_to_id(header)}",
-            header <> " - #{map.title}",
-            :extras,
-            body
-          )
-        end
-
-      [intro_json_item | section_json_items]
-    end
-  end
-
-  defp extra_search_data(map, custom_search_data) do
-    Enum.map(custom_search_data, fn item ->
+  defp extra(%{search_data: search_data} = map) when is_list(search_data) do
+    Enum.map(search_data, fn item ->
       link =
         if item.anchor === "" do
           "#{map.id}.html"
@@ -59,6 +31,34 @@ defmodule ExDoc.Formatter.HTML.SearchData do
     end)
   end
 
+  defp extra(%{url: url} = map) do
+    [encode("#{map.id}", map.title, :extras, url)]
+  end
+
+  defp extra(map) do
+    {intro, sections} = extract_sections_from_markdown(map.source)
+
+    intro_json_item =
+      encode(
+        "#{map.id}.html",
+        map.title,
+        :extras,
+        intro
+      )
+
+    section_json_items =
+      for {header, body} <- sections do
+        encode(
+          "#{map.id}.html##{Utils.text_to_id(header)}",
+          header <> " - #{map.title}",
+          :extras,
+          body
+        )
+      end
+
+    [intro_json_item | section_json_items]
+  end
+
   defp module(%ExDoc.ModuleNode{} = node) do
     {intro, sections} = extract_sections(node.doc_format, node)
 

lib/ex_doc/formatter/html/search_data.ex

@@ -82,15 +82,9 @@ defmodule ExDoc.Formatter.HTML.Templates do
 
   defp sidebar_extras(extras) do
     for extra <- extras do
-      %{id: id, title: title, group: group, content: content} = extra
+      %{id: id, title: title, group: group} = extra
 
-      item =
-        %{
-          id: to_string(id),
-          title: to_string(title),
-          group: to_string(group),
-          headers: extract_headers(content)
-        }
+      item = %{id: to_string(id), title: to_string(title), group: to_string(group)}
 
       case extra do
         %{search_data: search_data} when is_list(search_data) ->
@@ -103,10 +97,15 @@ defmodule ExDoc.Formatter.HTML.Templates do
               }
             end)
 
-          Map.put(item, :searchData, search_data)
+          item
+          |> Map.put(:headers, extract_headers(extra.content))
+          |> Map.put(:searchData, search_data)
+
+        %{url: url} when is_binary(url) ->
+          Map.put(item, :url, url)
 
         _ ->
-          item
+          Map.put(item, :headers, extract_headers(extra.content))
       end
     end
   end

lib/ex_doc/formatter/html/templates.ex

@@ -1,5 +1,5 @@
 %{
-  "earmark_parser": {:hex, :earmark_parser, "1.4.43", "34b2f401fe473080e39ff2b90feb8ddfeef7639f8ee0bbf71bb41911831d77c5", [:mix], [], "hexpm", "970a3cd19503f5e8e527a190662be2cee5d98eed1ff72ed9b3d1a3d466692de8"},
+  "earmark_parser": {:hex, :earmark_parser, "1.4.44", "f20830dd6b5c77afe2b063777ddbbff09f9759396500cdbe7523efd58d7a339c", [:mix], [], "hexpm", "4778ac752b4701a5599215f7030989c989ffdc4f6df457c5f36938cc2d2a2750"},
   "easyhtml": {:hex, :easyhtml, "0.3.2", "050adfc8074f53b261f7dfe83303d864f1fbf5988245b369f8fdff1bf4c4b3e6", [:mix], [{:floki, "~> 0.35", [hex: :floki, repo: "hexpm", optional: false]}], "hexpm", "b6a936f91612a4870aa3e828cd8da5a08d9e3b6221b4d3012b6ec70b87845d06"},
   "floki": {:hex, :floki, "0.36.2", "a7da0193538c93f937714a6704369711998a51a6164a222d710ebd54020aa7a3", [:mix], [], "hexpm", "a8766c0bc92f074e5cb36c4f9961982eda84c5d2b8e979ca67f5c268ec8ed580"},
   "jason": {:hex, :jason, "1.4.4", "b9226785a9aa77b6857ca22832cffa5d5011a667207eb2a0ad56adb5db443b8a", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "c5eb0cab91f094599f94d55bc63409236a8ec69a21a67814529e8d5f6cc90b3b"},

mix.lock

@@ -112,6 +112,20 @@ defmodule ExDoc.Formatter.HTMLTest do
     assert to_string(bar_content["h1"]) == "README bar"
   end
 
+  test "extras defined as external urls", %{tmp_dir: tmp_dir} = context do
+    config =
+      doc_config(context, extras: ["README.md", "Elixir": [url: "https://elixir-lang.org"]])
+
+    File.write!("#{tmp_dir}/README.md", "README")
+
+    generate_docs(config)
+
+    # Verify necessary files in .build
+    content = File.read!(tmp_dir <> "/html/README.html")
+
+    assert content =~ "https://elixir-lang.org"
+  end
+
   test "warns when generating an index.html file with an invalid redirect",
        %{tmp_dir: tmp_dir} = context do
     output =