+class MultiQuerySet(object):
+ def __init__(self, *args, **kwargs):
+ self.querysets = args
+ self._count = None
+
+ def count(self):
+ if not self._count:
+ self._count = sum(len(qs) for qs in self.querysets)
+ return self._count
+
+ def __len__(self):
+ return self.count()
+
+ def __getitem__(self, item):
+ try:
+ indices = (offset, stop, step) = item.indices(self.count())
+ except AttributeError:
+ # it's not a slice - make it one
+ return self[item : item + 1][0]
+ items = []
+ total_len = stop - offset
+ for qs in self.querysets:
+ if len(qs) < offset:
+ offset -= len(qs)
+ else:
+ items += list(qs[offset:stop])
+ if len(items) >= total_len:
+ return items
+ else:
+ offset = 0
+ stop = total_len - len(items)
+ continue
+
+
+def truncate_html_words(s, num, end_text='...'):
+ """Truncates HTML to a certain number of words (not counting tags and
+ comments). Closes opened tags if they were correctly closed in the given
+ html. Takes an optional argument of what should be used to notify that the
+ string has been truncated, defaulting to ellipsis (...).
+
+ Newlines in the HTML are preserved.
+
+ This is just a version of django.utils.text.truncate_html_words with no space before the end_text.
+ """
+ s = force_unicode(s)
+ length = int(num)
+ if length <= 0:
+ return u''
+ html4_singlets = ('br', 'col', 'link', 'base', 'img', 'param', 'area', 'hr', 'input')
+ # Set up regular expressions
+ re_words = re.compile(r'&.*?;|<.*?>|(\w[\w-]*)', re.U)
+ re_tag = re.compile(r'<(/)?([^ ]+?)(?: (/)| .*?)?>')
+ # Count non-HTML words and keep note of open tags
+ pos = 0
+ end_text_pos = 0
+ words = 0
+ open_tags = []
+ while words <= length:
+ m = re_words.search(s, pos)
+ if not m:
+ # Checked through whole string
+ break
+ pos = m.end(0)
+ if m.group(1):
+ # It's an actual non-HTML word
+ words += 1
+ if words == length:
+ end_text_pos = pos
+ continue
+ # Check for tag
+ tag = re_tag.match(m.group(0))
+ if not tag or end_text_pos:
+ # Don't worry about non tags or tags after our truncate point
+ continue
+ closing_tag, tagname, self_closing = tag.groups()
+ tagname = tagname.lower() # Element names are always case-insensitive
+ 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)
+ if words <= length:
+ # Don't try to close tags if we don't need to truncate
+ return s
+ out = s[:end_text_pos]
+ if end_text:
+ out += end_text
+ # Close any tags still open
+ for tag in open_tags:
+ out += '</%s>' % tag
+ # Return string
+ return out
+
+
+def customizations_hash(customizations):
+ customizations.sort()
+ return hash(tuple(customizations))
+
+
+def get_customized_pdf_path(book, customizations):
+ """
+ Returns a MEDIA_ROOT relative path for a customized pdf. The name will contain a hash of customization options.
+ """
+ h = customizations_hash(customizations)
+ return 'book/%s/%s-custom-%s.pdf' % (book.slug, book.slug, h)
+
+
+def clear_custom_pdf(book):
+ """
+ Returns a list of paths to generated customized pdf of a book
+ """
+ from waiter.utils import clear_cache
+ clear_cache('book/%s' % book.slug)
+
+
+class AppSettings(object):
+ """Allows specyfying custom settings for an app, with default values.
+
+ Just subclass, set some properties and instantiate with a prefix.
+ Getting a SETTING from an instance will check for prefix_SETTING
+ in project settings if set, else take the default. The value will be
+ then filtered through _more_SETTING method, if there is one.
+
+ """
+ def __init__(self, prefix):
+ self._prefix = prefix
+
+ def __getattribute__(self, name):
+ if name.startswith('_'):
+ return object.__getattribute__(self, name)
+ value = getattr(settings,
+ "%s_%s" % (self._prefix, name),
+ object.__getattribute__(self, name))
+ more = "_more_%s" % name
+ if hasattr(self, more):
+ value = getattr(self, more)(value)
+ return value
+
+
+def trim_query_log(trim_to=25):
+ """
+connection.queries includes all SQL statements -- INSERTs, UPDATES, SELECTs, etc. Each time your app hits the database, the query will be recorded.
+This can sometimes occupy lots of memory, so trim it here a bit.
+ """
+ if settings.DEBUG:
+ from django.db import connection
+ connection.queries = trim_to > 0 \
+ and connection.queries[-trim_to:] \
+ or []
+
+
+def related_tag_name(tag_info, language=None):
+ return tag_info.get("name_%s" % (language or get_language()),
+ tag_info.get("name_%s" % settings.LANGUAGE_CODE, ""))
+
+
+def delete_from_cache_by_language(cache, key_template):
+ cache.delete_many([key_template % lc for lc, ln in settings.LANGUAGES])