regexp in django orm

RE_REPLACEMENTS = {
    "postgresql": [
        ("{begin-word}", r"\m"),
        ("{end-word}", r"\M"),
    ],
    "mysql": [
        ("{begin-word}", "[[:<:]]"),
        ("{end-word}", "[[:>:]]"),
    ],
    "oracle": [
        ("{begin-word}", r"(^|\W)"), # HACK!
        ("{end-word}", r"(\W|$)"), # HACK!
    ],
    "_default_": [
        ("{begin-word}", r"\b"),
        ("{end-word}", r"\b"),
    ]
}

def regexp_for_django_orm(re_regexp):
    from django.db import connection
    rules = RE_REPLACEMENTS.get(connection.vendor, RE_REPLACEMENTS["_default_"])
    for pattern, replacement in rules:
        re_regexp = re_regexp.replace(pattern, replacement)
    return re_regexp


#usage
MyModel.objects.filter(column_iregex = regexp_for_django_orm("{begin-word}WORD{end-word}") )