Truncate line breaks

boards/templates/boards/post.html

@@ -83,7 +83,7 b''
     {% endcomment %}
     <div class="message">
         {% if truncated %}
-            {{ post.get_text|truncatewords_html:50|safe }}
+            {{ post.get_text|truncatewords_html:50|truncatenewlines_html:3|safe }}
         {% else %}
             {{ post.get_text|safe }}
         {% endif %}

boards/templatetags/board.py

@@ -1,9 +1,18 b''
 import re
+
 from django.shortcuts import get_object_or_404
 from django import template
+from django.utils.text import re_tag
+
+from boards.mdx_neboard import LINE_BREAK_HTML
 
 
 IMG_ACTION_URL = '[<a href="{}">{}</a>]'
+REGEX_NEWLINE = re.compile(LINE_BREAK_HTML)
+TRUNCATOR = '...'
+HTML4_SINGLETS =(
+    'br', 'col', 'link', 'base', 'img', 'param', 'area', 'hr', 'input'
+)
 
 
 register = template.Library()
@@ -49,3 +58,59 b' def post_view(context, post, *args, **kw'
 def page_url(paginator, page_number, *args, **kwargs):
     if paginator.supports_urls():
         return paginator.get_page_url(page_number)
+
+
[e-mail](name='truncatenewlines_html')
+def truncatenewlines_html(value, arg):
+    current_pos = 0
+    match_count = 0
+
+    # Collect places for truncation
+    while match_count <= arg:
+        m = REGEX_NEWLINE.search(value, current_pos)
+        if m is None:
+            break
+        else:
+            match_count += 1
+            current_pos = m.end()
+
+    # Find and close open tags
+    if match_count > arg:
+        truncate_pos = current_pos
+
+        open_tags = []
+        text = value[:truncate_pos]
+        current_pos = 0
+        while True:
+            tag = re_tag.search(text, current_pos)
+            if tag is None:
+                break
+            else:
+                closing_tag, tagname, self_closing = tag.groups()
+                tagname = tagname.lower()
+                if self_closing or tagname in HTML4_SINGLETS:
+                    pass
+                elif closing_tag:
+                    # Check for match in open tags list
+                    try:
+                        i = open_tags.index(tagname)
+                    except ValueError:
+                        pass
+                    else:
+                        # SGML: An end tag closes, back to the matching start tag,
+                        # all unclosed intervening start tags with omitted end tags
+                        open_tags = open_tags[i + 1:]
+                else:
+                    # Add it to the start of the open tags list
+                    open_tags.insert(0, tagname)
+
+                current_pos = tag.end()
+
+        for tag in open_tags:
+            text += '</%s>'.format(tag)
+        text += TRUNCATOR
+    else:
+        text = value
+
+    return text
+