`breadcrumbs_on_rails` builder with Bulma compatible output

bulma_breadcrumbs_builder.rb

# `BulmaBreadcrumbsBuilder `is a Bulma compatible breadcrumb
# builder. It is designed to work with the `breadcrumbs_on_rails` gem as a
# drop-in builder replacement.
#
# BulmaBreadcrumbsBuilder accepts a limited set of options:
#
#   | option           | default | description                                |
#   | ---------------- | ------- | ------------------------------------------ |
#   | `:container_tag` | `:ol`   | What tag to use for the list container     |
#   | `:tag`           | `:li`   | What HTML tag to use for breadcrumb items  |
#   | `:show_empty`    | `false` | Whether to render container when no crumbs |
#
# You can use it by passing it to the `:builder` option on `render_breadcrumbs`:
#
#   <nav class="breadcrumb" aria-label="breadcrumbs">
#     <%= render_breadcrumbs builder: ::BulmaBreadcrumbsBuilder %>
#   </nav>
#
# You will need to place this class in a location that is loaded by Rails. One
# suggested is `lib/bulma_breadcrumbs_builder.rb`. You may need to adjust
# Rails' load path in `config/application.rb`:
#
#   config.eager_load_paths << Rails.root.join('lib')
#
#
# See also:
#  <http://bulma.io/documentation/components/breadcrumb/>
#
# Based on:
#  - BreadcrumbsOnRails::Breadcrumbs::SimpleBuilder
#      <https://github.com/weppos/breadcrumbs_on_rails/blob/v3.0.1/lib/breadcrumbs_on_rails/breadcrumbs.rb#L79>
#  - BootstrapBreadcrumbsBuilder
#      <https://gist.github.com/riyad/1933884>
#  - Bootstrap4BreadcrumbsBuilder
#      <https://gist.github.com/SaladFork/270a4cb3ac20be9715b7117551c31ec7>
#
class BulmaBreadcrumbsBuilder < BreadcrumbsOnRails::Breadcrumbs::Builder
  def render
    return '' unless should_render?

    container_tag = @options.fetch(:container_tag, :ul)

    @context.content_tag container_tag, class: nil do
      @elements.collect do |element|
        render_element(element)
      end.join.html_safe
    end
  end

  def render_element(element)
    name = compute_name(element)
    path = compute_path(element)

    current = @context.current_page?(path)

    item_tag = @options.fetch(:tag, :li)

    @context.content_tag(item_tag, class: [('is-active' if current)]) do
      @context.link_to(name, path, element.options)
    end
  end

  private

  def should_render?
    @elements.any? || @options[:show_empty]
  end
end