prev_next.html

{%- comment -%}
  Renders previous/next navigation for the linear reading path of the manual.
  Used by _layouts/linear.html. Sequence is defined in _data/linear_sequence.yml.
  Finds the current page by matching page.path against entries in the sequence,
  then resolves neighbors to real page objects so we get URLs and titles for free.
{%- endcomment -%}
{%- assign seq = site.data.linear_sequence -%}
{%- assign current_index = -1 -%}
{%- for entry in seq -%}
  {%- if entry == page.path -%}
    {%- assign current_index = forloop.index0 -%}
  {%- endif -%}
{%- endfor -%}
{%- if current_index >= 0 -%}
  {%- assign prev_index = current_index | minus: 1 -%}
  {%- assign next_index = current_index | plus: 1 -%}
  {%- assign last_index = seq.size | minus: 1 -%}
  {%- assign prev_path = "" -%}
  {%- assign next_path = "" -%}
  {%- for entry in seq -%}
    {%- if forloop.index0 == prev_index -%}{%- assign prev_path = entry -%}{%- endif -%}
    {%- if forloop.index0 == next_index -%}{%- assign next_path = entry -%}{%- endif -%}
  {%- endfor -%}
  {%- assign prev_page = site.pages | where: "path", prev_path | first -%}
  {%- assign next_page = site.pages | where: "path", next_path | first -%}
  <nav class="prev-next-nav" aria-label="Reading sequence navigation">
    <div class="prev-next-nav__prev">
      {%- if current_index > 0 and prev_page -%}
        <a href="{{ prev_page.url | relative_url }}">
          <span class="prev-next-nav__label">&larr; Previous</span>
          <span class="prev-next-nav__title">{{ prev_page.title }}</span>
        </a>
      {%- endif -%}
    </div>
    <div class="prev-next-nav__next">
      {%- if current_index < last_index and next_page -%}
        <a href="{{ next_page.url | relative_url }}">
          <span class="prev-next-nav__label">Next &rarr;</span>
          <span class="prev-next-nav__title">{{ next_page.title }}</span>
        </a>
      {%- endif -%}
    </div>
  </nav>
{%- endif -%}