This is not the exact answer but the solution based on the question. After searching awhile on the net I implemented the following.

This is my custom tag (see how to do it).

from django.template.defaultfilters import register
from django.utils.html import escape
from django.utils.safestring import mark_safe

@register.simple_tag
def highlight(string, entry, prefix, suffix):
    string = escape(string)
    entry = escape(entry)
    string_upper = string.upper()
    entry_upper = entry.upper()
    result = ''
    length = len(entry)
    start = 0
    pos = string_upper.find(entry_upper, start)
    while pos >= 0:
        result += string[start:pos]
        start = pos + length
        result += prefix + string[pos:start] + suffix
        pos = string_upper.find(entry_upper, start)
    result += string[start:len(string)]
    return mark_safe(result)

It accepts unsafe string and returns the escaped result.

Use it this way:

<span class="entityCode">{% highlight entity.code search_text '<span class="highlighted">' '</span>' %}</span>

I use a nested <span> to inherit all the style. And it shows something like

a[0:a.lower().find("feat.")].rstrip() would do.

anding

"string1" and "string2" and ... and "stringN"

returns the the last string.

oring

"string1" or "string2" or ... or "stringN"

would return the first string.

Short-circuit evaluation.

Create a re.RegexObject using re.compile() and then call it's split() method.

Example:

>>> re.compile('XYZ', re.IGNORECASE).split('fooxyzbar')
['foo', 'bar']

Using re is the best solution even if you think it's complicated.

To replace all occurrences of 'abc', 'ABC', 'Abc', etc., with 'Python', say:

re.sub(r'(?i)abc', 'Python', a)

Example session:

>>> a = 'abc  asd   Abc  asd  ABCDE    XXAbCXX'
>>> import re
>>> re.sub(r'(?i)abc', 'Python', a)
'Python  asd   Python  asd  PythonDE    XXPythonXX'
>>> 

Note how embedding (?i) at the start of the regexp makes it case insensitive. Also note the r'...' string literal for the regexp (which in this specific case is redundant but helps as soon as you use a regexp that has backslashes (\) in them.

import re
pattern = re.compile("hello", re.IGNORECASE)
pattern.sub("bye", "hello HeLLo HELLO")
# 'bye bye bye'