<div id="classindex-section" class="nav-section">
  <h3>Class and Module Index</h3>

  <%-
  all_classes = @classes.group_by do |klass|
    klass.full_name[/\A[^:]++(?:::[^:]++(?=::))*+(?=::[^:]*+\z)/]
  end.delete_if do |_, klasses|
    !klasses.any?(&:display?)
  end
  link = proc do |index_klass, display = index_klass.display?|
    if display
      -%><code><a href="<%= rel_prefix %>/<%= index_klass.path %>"><%= index_klass.name %></a></code><%-
    else
      -%><code><%= index_klass.name %></code><%-
    end
  end
  if top = all_classes[nil]
    solo = top.one? {|klass| klass.display?}
    traverse = proc do |klasses| -%>
  <ul class="link-list">
      <%- klasses.each do |index_klass| -%>
        <%- if children = all_classes[index_klass.full_name] -%>
  <li><details<% if solo; solo = false %> open<% end %>><summary><% link.call(index_klass) %></summary>
          <%- traverse.call(children) -%>
  </ul></details>
        <%- elsif index_klass.display? -%>
  <li><% link.call(index_klass, true) %>
        <%- end -%>
      <%- end -%>
    <%- end -%>
    <%- traverse.call(top) -%>
  <%- end -%>
</div>