Support m:Module#anchor, closes #1832

Author: wojtekmach

README.md

@@ -224,8 +224,9 @@ Link to extra pages in another application using the syntax `` [Writing Document
 
 It is also possible to place anchors after the module name and extra pages. For example:
 
-* `` `Keyword#module-duplicate-keys-and-ordering` `` will create a link to `https://hexdocs.pm/elixir/Keyword.html#module-duplicate-keys-and-ordering`
-* `` `e:elixir:syntax-reference.md#expressions` `` will create a link to `https://hexdocs.pm/elixir/syntax-reference.html#expressions`
+  * `` `m:Keyword#module-duplicate-keys-and-ordering` `` will create a link to `https://hexdocs.pm/elixir/Keyword.html#module-duplicate-keys-and-ordering`
+
+  * `` `e:elixir:syntax-reference.md#expressions` `` will create a link to `https://hexdocs.pm/elixir/syntax-reference.html#expressions`
 
 ### Erlang
 
@@ -241,8 +242,9 @@ Link to extra pages in another application using the syntax `` [Using unicode](`
 
 It is also possible to place anchors after the module name and extra pages. For example:
 
-* `` `m:argparse#quick-start` `` will create a link to `https://erlang.org/doc/man/argparse#quick-start`
-* `` `e:stdlib:unicode-usage.md#what-unicode-is` `` will create a link to `https://erlang.org/doc/apps/stdlib/unicode-usage.html#what-unicode-is`
+  * `` `m:argparse#quick-start` `` will create a link to `https://erlang.org/doc/man/argparse#quick-start`
+
+  * `` `e:stdlib:unicode-usage.md#what-unicode-is` `` will create a link to `https://erlang.org/doc/apps/stdlib/unicode-usage.html#what-unicode-is`
 
 <!-- tabs-close -->
 

lib/ex_doc/autolink.ex

@@ -231,8 +231,7 @@ defmodule ExDoc.Autolink do
          true <- is_binary(path) and path != "" and not (path =~ @ref_regex),
          true <- Path.extname(path) in @builtin_ext do
       if file = config.extras[Path.basename(path)] do
-        fragment = (uri.fragment && "#" <> uri.fragment) || ""
-        file <> config.ext <> fragment
+        append_fragment(file <> config.ext, uri.fragment)
       else
         maybe_warn(config, nil, nil, %{file_path: path, original_text: link})
         nil
@@ -350,14 +349,14 @@ defmodule ExDoc.Autolink do
       nil ->
         case string do
           "m:" <> rest ->
+            destructure [rest, fragment], String.split(rest, "#", parts: 2)
+
             # TODO: rename :custom_link to :strict i.e. we expect ref to be valid
             # force custom_link mode because of m: prefix.
             case config.language.parse_module(rest, :custom_link) do
               {:module, module} ->
-                module_url(module, :custom_link, config, rest)
-
-              {:module, module, anchor} ->
-                module_url(module, "#" <> anchor, :custom_link, config, rest)
+                url = module_url(module, :custom_link, config, rest)
+                url && append_fragment(url, fragment)
 
               :error ->
                 nil
@@ -371,9 +370,6 @@ defmodule ExDoc.Autolink do
               {:module, module} ->
                 module_url(module, mode, config, string)
 
-              {:module, module, anchor} ->
-                module_url(module, "#" <> anchor, mode, config, string)
-
               :error ->
                 nil
             end
@@ -604,4 +600,7 @@ defmodule ExDoc.Autolink do
   # for the rest, it can either be undefined or private
   defp format_visibility(:undefined, _kind), do: "undefined or private"
   defp format_visibility(visibility, _kind), do: "#{visibility}"
+
+  defp append_fragment(url, nil), do: url
+  defp append_fragment(url, fragment), do: url <> "#" <> fragment
 end

lib/ex_doc/language/elixir.ex

@@ -599,7 +599,11 @@ defmodule ExDoc.Language.Elixir do
 
     case Autolink.url(code, :regular_link, config) do
       url when is_binary(url) ->
-        code = remove_prefix(code)
+        code =
+          code
+          |> remove_prefix()
+          |> remove_fragment()
+
         {:a, [href: url], [{:code, attrs, [code], meta}], %{}}
 
       :remove_link ->
@@ -623,6 +627,10 @@ defmodule ExDoc.Language.Elixir do
   defp remove_prefix("m:" <> rest), do: rest
   defp remove_prefix(rest), do: rest
 
+  defp remove_fragment(string) do
+    string |> String.split("#") |> hd()
+  end
+
   defp safe_format_string!(string) do
     try do
       string

lib/ex_doc/language/erlang.ex

@@ -443,7 +443,7 @@ defmodule ExDoc.Language.Erlang do
   def parse_module_function(string) do
     case String.split(string, ":") do
       [module_string, function_string] ->
-        with {:module, module} <- parse_module_string(module_string, :custom_link),
+        with {:module, module} <- parse_module(module_string, :custom_link),
              {:function, function} <- parse_function(function_string) do
           {:remote, module, function}
         end
@@ -489,23 +489,7 @@ defmodule ExDoc.Language.Erlang do
   end
 
   @impl true
-  def parse_module(string, mode) do
-    case String.split(string, "#", parts: 2) do
-      [mod, anchor] ->
-        case parse_module_string(mod, mode) do
-          {:module, mod} ->
-            {:module, mod, anchor}
-
-          :error ->
-            :error
-        end
-
-      [mod] ->
-        parse_module_string(mod, mode)
-    end
-  end
-
-  defp parse_module_string(string, _mode) do
+  def parse_module(string, _mode) do
     case :erl_scan.string(String.to_charlist(string)) do
       {:ok, [{:atom, _, module}], _} when is_atom(module) ->
         {:module, module}

test/ex_doc/language/elixir_test.exs

@@ -24,10 +24,34 @@ defmodule ExDoc.Language.ElixirTest do
       assert autolink_doc("`PATH`") == ~s|<code class="inline">PATH</code>|
     end
 
-    test "erlang module" do
+    test "erlang module does not link" do
       assert autolink_doc("`:array`") == ~s|<code class="inline">:array</code>|
     end
 
+    test "m:module" do
+      assert autolink_doc("`m:String`") ==
+               ~s|<a href="https://hexdocs.pm/elixir/String.html"><code class="inline">String</code></a>|
+    end
+
+    test "m:module fragment" do
+      assert autolink_doc("`m:String#fragment`") ==
+               ~s|<a href="https://hexdocs.pm/elixir/String.html#fragment"><code class="inline">String</code></a>|
+    end
+
+    test "m:module with Erlang module" do
+      assert autolink_doc("`m::array`") ==
+               ~s|<a href="https://www.erlang.org/doc/man/array.html"><code class="inline">:array</code></a>|
+    end
+
+    test "m:module with Erlang module and fragment" do
+      assert autolink_doc("`m::array#fragment`") ==
+               ~s|<a href="https://www.erlang.org/doc/man/array.html#fragment"><code class="inline">:array</code></a>|
+    end
+
+    test "module with fragment without m: does not link" do
+      assert autolink_doc("`String#anchor`") == ~s|<code class="inline">String#anchor</code>|
+    end
+
     test "unknown module" do
       assert autolink_doc("`Unknown`") == ~s|<code class="inline">Unknown</code>|
       assert autolink_doc("`:unknown`") == ~s|<code class="inline">:unknown</code>|
@@ -38,9 +62,6 @@ defmodule ExDoc.Language.ElixirTest do
       assert autolink_doc("`ExDoc.Markdown`") ==
                ~s|<a href="ExDoc.Markdown.html"><code class="inline">ExDoc.Markdown</code></a>|
 
-      assert autolink_doc("`m:ExDoc.Markdown`") ==
-               ~s|<a href="ExDoc.Markdown.html"><code class="inline">ExDoc.Markdown</code></a>|
-
       assert autolink_doc("`String`", apps: [:elixir]) ==
                ~s|<a href="String.html"><code class="inline">String</code></a>|
     end