'''regex.py

   Jeff Ondich, 16 Jan 2009

   This program gives a brief illustration of a few of the
   features of the re (regular expression) module.

   The re module has a lot of complicated and powerful features.
   You can find the official documentation here:

     http://docs.python.org/library/re.html
'''

import re

# We're going to look for stuff inside the following string.
s = 'a frog, a dog, and a hog, were agog on the log in the bog'

print 'This program will perform regular expression searches on the string:'
print '  "%s"' % s
print

# Find a simple match
regex = 'hog'
print 'Looking for "%s".' % regex
result = re.search(regex, s)
if result:
    print 'The first match goes from index %d to %d' % (result.start(), result.end() - 1)
else:
    print 'No match found.'
print

# Find a sequence of letters ending in "og".
regex = '(\w*og)\W'
print 'Looking for "%s".' % regex
result = re.search(regex, s)
if result:
    print 'Found "%s"' % result.groups()[0]
else:
    print 'No match found.'
print

# Find all the sequences of letters ending in "og".
regex = '\w*og\\b' # Any guesses why we do \\b instead of \b?
print 'Looking for all occurrences of "%s".' % regex
result = re.findall(regex, s)
if result:
    print result
else:
    print 'No match found.'
print

# Split the string on a pattern.
regex = '\w*og\\b'
print 'Splitting the string on all occurrences of "%s".' % regex
result = re.split(regex, s)
if result:
    print result
else:
    print 'No match found.'
print

# Replace all og-words with OGWORD.
regex = '\w*og\\b'
print 'Splitting the string on all occurrences of "%s".' % regex
print re.sub(regex, 'OGWORD', s)
print