page_url.liquid

{% capture function %}
  {% comment note:
    Shopify, crazily enough, does not have a global object that returns the current url like it does for the page_title.
    So lets fake one.
    It will take into account filtered collections.
    It will not take into account url params and hash anchors, because reasons.
    page_url_with_shop_domain gives you the page_url with the shop.url prepended.
   %}{% endcomment %}
   
  {% if template contains '404' %}
    {% assign page_url = '/404' %}
  {% elsif template contains 'article' %}
    {% assign page_url = article.url %}
  {% elsif template contains 'blog' %}
    {% assign page_url = blog.url %}
  {% elsif template contains 'cart' %}
    {% assign page_url = '/cart' %}
  {% elsif template contains 'list-collections' %}
    {% assign page_url = '/collections' %}
  {% elsif template contains 'collection' %}
    {% if collection.url != blank %}
      {% assign page_url = collection.url %}
    {% else %}
      {% assign page_url = '/collections/all' %}
    {% endif %}
    {% if current_tags.size > 0 %}
      {% capture current_tag_params %}{% endcapture %}
      {% for current_tag in current_tags %}
        {% capture current_tag_params %}{{ current_tag_params }}{% unless forloop.first %}+{% endunless %}{{ current_tag | handle }}{% endcapture %}
      {% endfor %}
      {% assign page_url = page_url | append: '/' | append: current_tag_params %}
    {% endif %}
  {% elsif template contains 'index' %}
    {% assign page_url = '/' %}
  {% elsif template contains 'page' %}
    {% assign page_url = page.url %}
  {% elsif template contains 'product' %}
    {% assign page_url = product.url %}
  {% elsif template contains 'search' %}
    {% assign page_url = '/search' %}
  {% elsif template contains 'customers' %}
    {% if template contains 'activate_account' %}
      {% assign page_url = '/account/activate' %}
    {% elsif template contains 'account' %}
      {% assign page_url = '/account' %}
    {% elsif template contains 'addresses' %}
      {% assign page_url = '/account/addresses' %}
    {% elsif template contains 'login' %}
      {% assign page_url = '/account/login' %}
    {% elsif template contains 'order' %}
      {% if order != blank %}
        {% assign page_url = order.customer_url | remove: shop.url %}
      {% else %}
        {% assign page_url = '/account/orders' %}
      {% endif %}
    {% elsif template contains 'register' %}
      {% assign page_url = '/account/register' %}
    {% elsif template contains 'reset' %}
      {% assign page_url = '/account/reset' %}
    {% else %}
      {% assign page_url = null %}
    {% endif %}
  {% else %}
    {% assign page_url = null %}
  {% endif %}
  
  {% if page_url != null %}
    {% assign page_url_with_shop_domain = page_url | prepend: shop.url %}
  {% endif %}
{% endcapture %}

UPDATE: Just use {{ request.path }} or to include the shops domain: {{ request.host }}{{ request.path }}