Split by a word (case insensitive)

You can use the re.split function with the re.IGNORECASE flag (or re.I for short):

>>> import re
>>> test = "hI MY NAME iS FoO bar"
>>> re.split("foo", test, flags=re.IGNORECASE)
['hI MY NAME iS ', ' bar']
>>>

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