python - Modifying a Regex Expression -

i have several strings match expressions want match , extract 2 words after prepositions along preps themselves.. , job . need modify regex such in case word "to" appears after preposition , regex extract preposition followed 3 words(instead of default 2 words..)
here's example elaborate:

str1 = " place near oberoi mall" str2 = " place next oberoi mall" 

expected results:-
res1 = "near oberoi mall" #extract 2 words after prep along (default case)
res2 = "next oberoi mall" #extract prep along 3 words after (in case "to" comes after preposition)

what have done?

def landmark(str):     preps = ['near','off','next','across','opposite','behind','above','ahead']     words = "|".join(re.escape(line.rstrip()) line in preps)     p1 = re.compile(r'(?:{})\s(\w+|\d+\w+)\s\w+'.format(words))     q =re.search(p1,str)     if q none:        return ""     else:         return q.group() 

my preps in list called preps in returning 2 words

res1 = "near oberoi mall" 

res2 = "next oberoi" #this becomes incomplete

what did try?
here:

p1 = re.compile(r'(?:{}(?:to)?)\s(\w+|\d+\w+)\s\w+'.format(words))   

*notice optional (?:to)? added it. there's small problem.. please help.

this worked example:

>>> p1 = re.compile(r'(?:%s)\s((?:to\s)?(\w+|\d+\w+)\s\w+)' % words) >>> dd = re.search(p1,str1) >>> dd.group() 'near oberoi mall' >>> cc = re.search(p1,str2) >>> cc.group() 'next oberoi mall'