{%- comment -%}
Override of jtd's site_nav.html. Splits the nav by language so that
visitors on /zh-cn/ pages see the Chinese sidebar, and everyone else
sees the English one. The filter is based on page URLs — pages whose
URL contains `/zh-cn/` are Chinese, everything else is English.
{%- endcomment -%}
{% assign is_zh = false %}
{% if page.url contains '/zh-cn/' %}{% assign is_zh = true %}{% endif %}
{%- comment -%}
Build lang_pages manually — Liquid's where_exp struggles with
negated `contains` expressions, so we loop and push explicitly.
{%- endcomment -%}
{% assign lang_pages = "" | split: "" %}
{% for p in site.html_pages %}
{% assign p_is_zh = false %}
{% if p.url contains '/zh-cn/' %}{% assign p_is_zh = true %}{% endif %}
{% if p_is_zh == is_zh %}
{% assign lang_pages = lang_pages | push: p %}
{% endif %}
{% endfor %}