Add breadcrumb list

lib/rdoc/class_module.rb

@@ -294,6 +294,25 @@ def full_name
                    end
   end
 
+  ##
+  # Return array of full_name splitted by +::+.
+
+  def nesting_namespaces
+    @namespaces ||= full_name.split("::").reject(&:empty?)
+  end
+
+  ##
+  # Return array of fully qualified nesting namespaces.
+  #
+  # For example, if full_name is +A::B::C+, this method returns <code>["A", "A::B", "A::B::C"]</code>
+
+  def fully_qualified_nesting_namespaces
+    return nesting_namespaces if nesting_namespaces.length < 2
+    @fqns ||= nesting_namespaces.inject([]) do |list, n|
+      list << (list.empty? ? n : "#{list.last}::#{n}")
+    end
+  end
+
   ##
   # TODO: filter included items by #display?
 

lib/rdoc/generator/darkfish.rb

@@ -350,6 +350,8 @@ def generate_class klass, template_file = nil
     asset_rel_prefix = rel_prefix + @asset_rel_path
     svninfo          = get_svninfo(current)
 
+    breadcrumb = generate_namespaces_breadcrumb(current, rel_prefix)
+
     @title = "#{klass.type} #{klass.full_name} - #{@options.title}"
 
     debug_msg "  rendering #{out_file}"
@@ -783,4 +785,22 @@ def template_for file, page = true, klass = ERB
     template
   end
 
+  private
+
+  def namespaces_to_class_modules klass
+    tree = {}
+
+    klass.namespaces.zip(klass.fully_qualified_namespaces) do |ns, fqns|
+      tree[ns] = @store.classes_hash[fqns] || @store.modules_hash[fqns]
+    end
+
+    tree
+  end
+
+  def generate_namespaces_breadcrumb klass, rel_prefix
+    namespaces_to_class_modules(klass).map do |namespace, class_module|
+      path = class_module ? (rel_prefix + class_module.path).to_s : ""
+      { name: namespace, path: path, self: klass.full_name == class_module&.full_name }
+    end
+  end
 end

lib/rdoc/generator/template/darkfish/class.rhtml

@@ -16,6 +16,20 @@
   </div>
 </nav>
 
+<nav role="navigation" aria-label="breadcrumb" class="breadcrumb">
+  <ol>
+    <% breadcrumb.each do |namespace| %>
+    <li>
+      <% if namespace[:self] %>
+      <span><%= namespace[:name] %></span>
+      <% else %>
+      <a href="<%= namespace[:path] %>"><%= namespace[:name] %></a><span>::</span>
+      <% end %>
+    </li>
+    <% end %>
+  </ol>
+</nav>
+
 <main role="main" aria-labelledby="<%=h klass.aref %>">
   <h1 id="<%=h klass.aref %>" class="<%= klass.type %>">
     <%= klass.type %> <%= klass.full_name %>

lib/rdoc/generator/template/darkfish/css/rdoc.css

@@ -273,6 +273,28 @@ nav h3,
   color: #555;
 }
 
+nav.breadcrumb {
+  display: block;
+  float: unset;
+  width: unset;
+  height: unset;
+  border: none;
+  position: unset;
+  top: unset;
+  padding-top: 10px;
+  padding-left: 20px;
+  margin-bottom: 1em;
+}
+
+nav.breadcrumb ol {
+  display: inline-block;
+}
+
+nav.breadcrumb li {
+  display: inline-block;
+  font-size: 125%;
+}
+
 nav ul,
 nav dl,
 nav p {

test/rdoc/test_rdoc_class_module.rb

@@ -1500,4 +1500,25 @@ def test_update_extends_with_colons
     assert_equal [a, c], @c1.extends
   end
 
+  def test_nesting_namespaces
+    cm1 = RDoc::ClassModule.new "A"
+    assert_equal ["A"], cm1.nesting_namespaces
+
+    cm2 = RDoc::ClassModule.new "A::B"
+    assert_equal ["A", "B"], cm2.nesting_namespaces
+
+    cm3 = RDoc::ClassModule.new "::A::B::C"
+    assert_equal ["A", "B", "C"], cm3.nesting_namespaces
+  end
+
+  def test_fully_qualified_nesting_namespaces
+    cm1 = RDoc::ClassModule.new "A"
+    assert_equal ["A"], cm1.fully_qualified_nesting_namespaces
+
+    cm2 = RDoc::ClassModule.new "A::B"
+    assert_equal ["A", "A::B"], cm2.fully_qualified_nesting_namespaces
+
+    cm3 = RDoc::ClassModule.new "::A::B::C"
+    assert_equal ["A", "A::B", "A::B::C"], cm3.fully_qualified_nesting_namespaces
+  end
 end