Fix: improve build time (#1358)

* Remove "passive" toggle

PR #1244 introduced the "passive" toggle, but just-the-docs.js subsequently disabled the only styling that used it, so it became redundant.
This removes it.

* Reduce build time for page-dependent CSS

Fix #1323

- Remove `_includes/head_nav.html`.
- Generate page-independent SCSS in `assets/css/just-the-docs-head-nav.css`.
- Link to `/assets/css/just-the-docs-head-nav.css` in `head.html`.
- Disable the above stylesheet in `assets/js/just-the-docs.js`.
- Generate page-dependent CSS in `_includes/css/activation.scss.liquid` and include in `head.html`.

* No override svg rotate

* Disable both stylesheets safely

* Move the site nav to a new include

- Fix the complete site nav
- Move the site nav to `_includes/site_nav.html`
- Cache the site nav
- Uncache `nav.html`

* Move nav and site_nav to _includes/components

* Replace id prefix

* Update breadcrumbs.html

Replace several filters by a single loop through all the pages,
but breaking as soon as possible.

Profiling indicates that this saves up to 50% of the breadcrumbs build time for the filters.

* Update just-the-docs-head-nav.css

Adjust the number of lines to keep

* Update head.html

Remove superflous type.

* Update activation.scss.liquid

Remove a superfluous closing brace.
Adjust layout.

* Use `scssify` to remove nesting

Preliminary profiling indicates that using `scssify` on the small number of nested CSS rules produced by `activation.scss.liquid` is quick enough.

* Update head.scss

Manual attempt at prettier (pending installation in Atom).

* Avoid generation of nested CSS

Local profiling indicated that using `scssify` on each page takes about 1% of the build time.

- Update `_includes/css/activation.scss.liquid` to generate non-nested CSS.
- Remove use of `scssify` from `_includes/head.html`.

* Ignore false positives from validator

Ignores: `:1.810-1.823: error: CSS: Parse Error.` and `:1.811-1.824: error: CSS: Parse Error.`; had to shift things around since the local config overrides the CI flag.

* Inline `_sass/head.css`

* Update CHANGELOG.md

---------

Co-authored-by: Matthew Wang <matt@matthewwang.me>

_includes/components/breadcrumbs.html

@@ -3,30 +3,38 @@
   Depends on: page, site.
   Results in: HTML for the breadcrumbs component.
   Overwrites:
-    pages_list, parent_page, grandparent_page.
+    node, pages_list, parent_page, grandparent_page.
 {%- endcomment -%}
 
 {%- if page.url != "/" and page.parent -%}
 
-  {%- assign pages_list = site[page.collection]
-      | default: site.html_pages
-      | where_exp: "item", "item.title != nil"
-      | where_exp: "item", "item.has_children != nil" -%}
+  {%- assign pages_list = site[page.collection] | default: site.html_pages -%}
 
-  {%- if page.grand_parent -%}
-    {%- assign parent_page = pages_list
-        | where: "title", page.parent
-        | where: "parent", page.grand_parent
-        | first -%}
-    {%- assign grandparent_page = pages_list
-        | where: "title", page.grand_parent
-        | first -%}
-  {%- else -%}
-    {%- assign parent_page = pages_list
-        | where: "title", page.parent
-        | where_exp: "item", "item.parent == nil"
-        | first -%}
-  {%- endif -%}
+  {%- assign parent_page = nil -%}
+  {%- assign grandparent_page = nil -%}
+
+  {%- for node in pages_list -%}
+  
+    {%- if node.has_children and page.grand_parent -%}
+
+      {%- if node.title == page.parent and node.parent == page.grand_parent -%}
+        {%- assign parent_page = node -%}
+      {%- endif -%}
+      {%- if node.title ==  page.grand_parent -%}
+        {%- assign grandparent_page = node -%}
+      {%- endif -%}
+      {%- if parent_page and grandparent_page -%}
+        {%- break -%}
+      {%- endif -%}
+
+    {%- elsif node.has_children and node.title == page.parent and node.parent == nil -%}
+
+      {%- assign parent_page = node -%}
+      {%- break -%}
+
+    {%- endif -%}
+
+  {%- endfor -%}
 
 <nav aria-label="Breadcrumb" class="breadcrumb-nav">
   <ol class="breadcrumb-nav-list">

_includes/components/nav.html

@@ -0,0 +1,75 @@
+{%- comment -%}
+  Include as: {%- include components/nav.html pages=pages -%}
+  Depends on: include.pages.
+  Results in: HTML for the navigation panel.
+  Includes:
+    sorted_pages.html
+  Overwrites:
+    nav_pages, first_level_pages, second_level_pages, third_level_pages,
+    node, children_list, child, grand_children_list, grand_child.
+{%- endcomment -%}
+
+{%- assign nav_pages = include.pages
+    | where_exp: "item", "item.title != nil"
+    | where_exp: "item", "item.nav_exclude != true" -%}
+
+{%- include sorted_pages.html pages = nav_pages -%}
+
+{%- comment -%}
+  It might be more efficient to sort the pages at each level separately.
+{%- endcomment -%}
+
+{%- assign first_level_pages = sorted_pages
+    | where_exp: "item", "item.parent == nil" -%}
+{%- assign second_level_pages = sorted_pages
+    | where_exp: "item", "item.parent != nil"
+    | where_exp: "item", "item.grand_parent == nil" -%}
+{%- assign third_level_pages = sorted_pages
+    | where_exp: "item", "item.grand_parent != nil" -%}
+
+<ul class="nav-list">
+{%- for node in first_level_pages -%}
+  <li class="nav-list-item">
+    {%- if node.has_children -%}
+    <button class="nav-list-expander btn-reset" aria-label="toggle items in {{ node.title }} category" aria-pressed="false">
+      <svg viewBox="0 0 24 24" aria-hidden="true"><use xlink:href="#svg-arrow-right"></use></svg>
+    </button>
+    {%- endif -%}
+    <a href="{{ node.url | relative_url }}" class="nav-list-link">{{ node.title }}</a>
+    {%- if node.has_children -%}
+      {%- assign children_list = second_level_pages
+            | where: "parent", node.title -%}
+      {%- if node.child_nav_order == 'desc' or node.child_nav_order == 'reversed' -%}
+        {%- assign children_list = children_list | reverse -%}
+      {%- endif -%}
+      <ul class="nav-list">
+      {%- for child in children_list -%}
+        <li class="nav-list-item">
+          {%- if child.has_children -%}
+          <button class="nav-list-expander btn-reset" aria-label="toggle items in {{ child.title }} category" aria-pressed="false">
+            <svg viewBox="0 0 24 24" aria-hidden="true"><use xlink:href="#svg-arrow-right"></use></svg>
+          </button>
+          {%- endif -%}
+          <a href="{{ child.url | relative_url }}" class="nav-list-link">{{ child.title }}</a>
+          {%- if child.has_children -%}
+            {%- assign grand_children_list = third_level_pages
+                  | where: "parent", child.title
+                  | where: "grand_parent", node.title -%}
+            {%- if child.child_nav_order == 'desc' or child.child_nav_order == 'reversed' -%}
+              {%- assign grand_children_list = grand_children_list | reverse -%}
+            {%- endif -%}
+            <ul class="nav-list">
+            {%- for grand_child in grand_children_list -%}
+              <li class="nav-list-item">
+                <a href="{{ grand_child.url | relative_url }}" class="nav-list-link">{{ grand_child.title }}</a>
+              </li>
+            {%- endfor -%}
+            </ul>
+          {%- endif -%}
+        </li>
+      {%- endfor -%}
+      </ul>
+    {%- endif -%}
+  </li>
+{%- endfor -%}
+</ul>

_includes/components/sidebar.html

@@ -3,10 +3,9 @@
   Depends on: page(?), site.
   Results in: HTML for the side bar.
   Includes:
-    title.html, nav.html, nav_footer_custom.html
+    title.html, components/site_nav.html, nav_footer_custom.html
   Overwrites: 
-    pages_top_size, collections_size, collection_entry,
-    collection_key, collection_value, collection, nav_footer_custom.
+    nav_footer_custom.
   Should not be cached, because nav_footer_custom.html might depend on page.
 {%- endcomment -%}
 
@@ -17,59 +16,9 @@
       <svg viewBox="0 0 24 24" class="icon" aria-hidden="true"><use xlink:href="#svg-menu"></use></svg>
     </button>
   </div>
-  <nav aria-label="Main" id="site-nav" class="site-nav">
-    {% assign pages_top_size = site.html_pages
-          | where_exp:"item", "item.title != nil"
-          | where_exp:"item", "item.parent == nil"
-          | where_exp:"item", "item.nav_exclude != true"
-          | size %}
-    {% if pages_top_size > 0 %}
-      {% include_cached nav.html pages=site.html_pages %}
-    {% endif %}
-    {%- if site.nav_external_links -%}
-      <ul class="nav-list">
-        {%- for node in site.nav_external_links -%}
-          <li class="nav-list-item external">
-            <a href="{{ node.url | absolute_url }}" class="nav-list-link external">
-              {{ node.title }}
-              {% unless node.hide_icon %}<svg viewBox="0 0 24 24" aria-labelledby="svg-external-link-title"><use xlink:href="#svg-external-link"></use></svg>{% endunless %}
-            </a>
-          </li>
-        {%- endfor -%}
-      </ul>
-    {%- endif -%}
-    {% if site.just_the_docs.collections %}
-      {% assign collections_size = site.just_the_docs.collections | size %}
-      {% for collection_entry in site.just_the_docs.collections %}
-        {% assign collection_key = collection_entry[0] %}
-        {% assign collection_value = collection_entry[1] %}
-        {% assign collection = site[collection_key] %}
-        {% if collection_value.nav_exclude != true %}
-          {% if collections_size > 1 or pages_top_size > 0 %}
-            {% if collection_value.nav_fold == true %}
-              <ul class="nav-list nav-category-list">
-                <li class="nav-list-item{% if page.collection == collection_key %} active{% endif %}">
-                  {%- if collection.size > 0 -%}
-                  <button class="nav-list-expander btn-reset" aria-label="Toggle collection {{ collection_value.name }}" aria-pressed="{% if page.collection == collection_key %}true{% else %}false{% endif %}">
-                    <svg viewBox="0 0 24 24" aria-hidden="true"><use xlink:href="#svg-arrow-right"></use></svg>
-                  </button>
-                  {%- endif -%}
-                  <div class="nav-category">{{ collection_value.name }}</div>
-                  {% include_cached nav.html pages=collection %}
-                </li>
-              </ul>
-            {% else %}
-              <div class="nav-category">{{ collection_value.name }}</div>
-              {% include_cached nav.html pages=collection %}
-            {% endif %}
-          {% else %}
-            {% include_cached nav.html pages=collection %}
-          {% endif %}
-        {% endif %}
-      {% endfor %}
-    {% endif %}
-  </nav>
-
+  
+  {% include_cached components/site_nav.html %}
+  
   {% capture nav_footer_custom %}
     {%- include nav_footer_custom.html -%}
   {% endcapture %}

_includes/components/site_nav.html

@@ -0,0 +1,63 @@
+{%- comment -%}
+  Include as: {%- include_cached components/site_nav.html -%}
+  Depends on: site.
+  Results in: HTML for the site-nav.
+  Includes:
+    components/nav.html
+  Overwrites: 
+    pages_top_size, collections_size, collection_entry,
+    collection_key, collection_value, collection.
+{%- endcomment -%}
+
+<nav aria-label="Main" id="site-nav" class="site-nav">
+  {% assign pages_top_size = site.html_pages
+        | where_exp:"item", "item.title != nil"
+        | where_exp:"item", "item.parent == nil"
+        | where_exp:"item", "item.nav_exclude != true"
+        | size %}
+  {% if pages_top_size > 0 %}
+    {% include components/nav.html pages=site.html_pages %}
+  {% endif %}
+  {%- if site.nav_external_links -%}
+    <ul class="nav-list">
+      {%- for node in site.nav_external_links -%}
+        <li class="nav-list-item external">
+          <a href="{{ node.url | absolute_url }}" class="nav-list-link external">
+            {{ node.title }}
+            {% unless node.hide_icon %}<svg viewBox="0 0 24 24" aria-labelledby="svg-external-link-title"><use xlink:href="#svg-external-link"></use></svg>{% endunless %}
+          </a>
+        </li>
+      {%- endfor -%}
+    </ul>
+  {%- endif -%}
+  {% if site.just_the_docs.collections %}
+    {% assign collections_size = site.just_the_docs.collections | size %}
+    {% for collection_entry in site.just_the_docs.collections %}
+      {% assign collection_key = collection_entry[0] %}
+      {% assign collection_value = collection_entry[1] %}
+      {% assign collection = site[collection_key] %}
+      {% if collection_value.nav_exclude != true %}
+        {% if collections_size > 1 or pages_top_size > 0 %}
+          {% if collection_value.nav_fold == true %}
+            <ul class="nav-list nav-category-list">
+              <li class="nav-list-item">
+                {%- if collection.size > 0 -%}
+                <button class="nav-list-expander btn-reset" aria-label="Toggle collection {{ collection_value.name }}" aria-pressed="false">
+                  <svg viewBox="0 0 24 24" aria-hidden="true"><use xlink:href="#svg-arrow-right"></use></svg>
+                </button>
+                {%- endif -%}
+                <div class="nav-category">{{ collection_value.name }}</div>
+                {% include components/nav.html pages=collection %}
+              </li>
+            </ul>
+          {% else %}
+            <div class="nav-category">{{ collection_value.name }}</div>
+            {% include components/nav.html pages=collection %}
+          {% endif %}
+        {% else %}
+          {% include components/nav.html pages=collection %}
+        {% endif %}
+      {% endif %}
+    {% endfor %}
+  {% endif %}
+</nav>