Add hreflang attribute to default themes

pelican/themes/simple/templates/article.html

@@ -5,6 +5,12 @@
 
 {% block head %}
   {{ super() }}
+
+  {% import 'translations.html' as translations with context %}
+  {% if translations.entry_hreflang(article) %}
+    {{ translations.entry_hreflang(article) }}
+  {% endif %}
+
   {% if article.description %}
     <meta name="description" content="{{article.description}}" />
   {% endif %}

pelican/themes/simple/templates/page.html

@@ -3,6 +3,15 @@
 
 {% block title %}{{ SITENAME }} - {{ page.title }}{%endblock%}
 
+{% block head %}
+  {{ super() }}
+
+  {% import 'translations.html' as translations with context %}
+  {% if translations.entry_hreflang(page) %}
+    {{ translations.entry_hreflang(page) }}
+  {% endif %}
+{% endblock %}
+
 {% block content %}
     <h1>{{ page.title }}</h1>
     {% import 'translations.html' as translations with context %}

pelican/themes/simple/templates/translations.html

@@ -1,9 +1,16 @@
 {% macro translations_for(article) %}
 {% if article.translations %}
-Translations: 
+Translations:
 {% for translation in article.translations %}
-<a href="{{ SITEURL }}/{{ translation.url }}">{{ translation.lang }}</a>
+<a href="{{ SITEURL }}/{{ translation.url }}" hreflang="{{ translation.lang }}">{{ translation.lang }}</a>
 {% endfor %}
 {% endif %}
 {% endmacro %}
 
+{% macro entry_hreflang(entry) %}
+{% if entry.translations %}
+  {% for translation in entry.translations %}
+    <link rel="alternate" hreflang="{{ translation.lang }}" href="{{ SITEURL }}/{{ translation.url }}">
+  {% endfor %}
+{% endif %}
+{% endmacro %}