Peter Mosses a4e4e312aa
Feature: Allow unlimited multi-level navigation (#1431)
* Allow unlimited multi-level navigation

This PR supersedes #462.

The only user-level difference from #462 is that disambiguation of parent pages has to use either `grand_parent` or `ancestor` titles: the somewhat unnatural `section_id` and `in_section` fields are not supported.

The implementation has been significantly simplified by the changes introduced in v0.7.0 of the theme.

* Detect cyclic parenthood

A page should not have a parent or ancestor with the same title. If it does, the location of the repeated link is marked by ∞, to facilitate debugging the navigation (and an unbounded loop leading to a build exception is avoided).

* Add nav_error_report warning in main navigation

When activated by `nav_error_report: true` in `_config.yml`, displays warnings about pages with the same title as their parent page or an ancestral page.

* Cache site-nav with links to all pages

The extra cached site-nav is used for determining breadcrumbs and children navigation, which may involve pages that are excluded from the main navigation.

* Replace code for determining children by inclusion of components/nav/children.html

* Update CHANGELOG.md

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Co-authored-by: Matt Wang <matt@matthewwang.me>
2024-08-20 22:34:11 +02:00

97 lines
3.2 KiB
HTML

{%- comment -%}
Include as: {%- include components/breadcrumbs.html -%}
Depends on: page, site.
Includes: components/site_nav.html.
Results in: HTML for the breadcrumbs component.
Overwrites:
nav_list_link, site_nav, nav_list_simple, nav_list_link_class, nav_category,
nav_anchor_splits, nav_breadcrumbs, nav_split, nav_split_next, nav_split_test,
nav_breadcrumb_link, nav_list_end_less, nav_list_end_count, nav_end_index, nav_breadcrumb.
{%- endcomment -%}
{%- if page.url != "/" and page.parent and page.title -%}
{%- capture nav_list_link -%}
<a href="{{ page.url | relative_url }}" class="nav-list-link">
{%- endcapture -%}
{%- capture site_nav -%}
{%- include_cached components/site_nav.html all=true -%}
{%- endcapture -%}
{%- capture nav_list_simple -%}
<ul class="nav-list">
{%- endcapture -%}
{%- capture nav_list_link_class %} class="nav-list-link">
{%- endcapture -%}
{%- capture nav_category -%}
<div class="nav-category">
{%- endcapture -%}
{%- assign nav_anchor_splits =
site_nav | split: nav_list_link |
first | split: nav_category |
last | split: "</a>" -%}
{%- comment -%}
The ordinary pages (if any) and the collections pages (if any) are separated by
occurrences of nav_category.
Any ancestor nav-links of the page are contained in the last group of pages,
immediately preceding nav-lists. After splitting at "</a>", the anchor that
was split is a potential ancestor link when the following split starts with
a nav-list.
The array nav_breadcrumbs is the stack of current potential ancestors of the
current page. A split that contains one or more "</ul>"s requires that number
of potential ancestors to be popped from the stack.
The number of occurrences of a string in nav_split_next is computed by removing
them all, then dividing the resulting size difference by the length of the string.
{%- endcomment %}
{%- assign nav_breadcrumbs = "" | split: "" -%}
{%- for nav_split in nav_anchor_splits -%}
{%- unless forloop.last -%}
{%- assign nav_split_next = nav_anchor_splits[forloop.index] | strip -%}
{%- assign nav_split_test =
nav_split_next | remove_first: nav_list_simple | prepend: nav_list_simple -%}
{%- if nav_split_test == nav_split_next -%}
{%- assign nav_breadcrumb_link =
nav_split | split: "<a " | last | prepend: "<a " |
replace: nav_list_link_class, ">" | append: "</a>" -%}
{%- assign nav_breadcrumbs = nav_breadcrumbs | push: nav_breadcrumb_link -%}
{%- endif -%}
{%- if nav_split_next contains "</ul>" -%}
{%- assign nav_list_end_less = nav_split_next | remove: "</ul>" -%}
{%- assign nav_list_end_count =
nav_split_next.size | minus: nav_list_end_less.size | divided_by: 5 -%}
{% for nav_end_index in (1..nav_list_end_count) %}
{%- assign nav_breadcrumbs = nav_breadcrumbs | pop -%}
{%- endfor -%}
{%- endif -%}
{%- endunless -%}
{%- endfor -%}
<nav aria-label="Breadcrumb" class="breadcrumb-nav">
<ol class="breadcrumb-nav-list">
{%- for nav_breadcrumb in nav_breadcrumbs %}
<li class="breadcrumb-nav-list-item">{{ nav_breadcrumb }}</li>
{%- endfor %}
<li class="breadcrumb-nav-list-item"><span>{{ page.title }}</span></li>
</ol>
</nav>
{% if site.nav_error_report %}
{{ nav_error_report }}
{% endif %}
{%- endif -%}