automatic jekyll breadcrumb

header_breadcrumb.html

{%- comment -%}
  Updated for boostrap 4 
  -- https://getbootstrap.com/docs/4.0/components/breadcrumb/ --
  and does not create a link for the last (active) item
{%- endcomment -%}
{%- assign url_parts = page.url | split: '/' -%}
{%- capture loop_max -%}{{ url_parts.size | minus: 1 }}{%- endcapture -%}
{%- assign j = loop_max | plus: 0 -%}
{%- assign bc_path = "/" -%}
{%- comment -%}
  the result of following assignment (if successful) will be an array, 
  so bc_page[0] is used to get the page corresponding to the path
{%- endcomment -%}
{%- assign bc_page = site.pages | where: "url", bc_path -%}
<div class="card-header">
  <nav aria-label="breadcrumb">
    <ol class="breadcrumb card-header lightcthru">
      <li class="breadcrumb-item">
        <a href="{{ bc_path | relative_url }}">
          {{ bc_page[0].breadcrumb }}
        </a>
      </li>
{%- for i in (1..loop_max) -%}
  {%- capture bc_path -%}{{bc_path}}{{url_parts[i]}}{%- endcapture -%}
  {%- unless bc_path contains ".html" -%}
    {%- capture bc_path -%}{{bc_path}}/{%- endcapture -%}
  {%- endunless -%}
  {%- comment -%}
    the result of following assignment (if successful) will be an array, 
    so bc_page[0] is used to get the page corresponding to the path
  {%- endcomment -%}
  {%- assign bc_page = site.pages | where: "url", bc_path -%}
  {% if bc_page and i < j %}
      <li class="breadcrumb-item">
        <a href="{{ bc_path | relative_url }}">
          {{ bc_page[0].breadcrumb }}
        </a>
      </li>
  {% elsif bc_page and i == j %}
      <li class="breadcrumb-item active">
        {{ bc_page[0].breadcrumb }}
      </li>
  {% endif %}
{%- endfor -%}
    </ol>
  </nav>
</div>