# Tested with Python 2.1
from __future__ import nested_scopes
import re
#
# The simplest, lambda-based implementation
#
def multiple_replace(dict, text):
""" Replace in 'text' all occurences of any key in the given
dictionary by its corresponding value. Returns the new tring."""
# Create a regular expression from the dictionary keys
regex = re.compile("(%s)" % "|".join(map(re.escape, dict.keys())))
# For each match, look-up corresponding value in dictionary
return regex.sub(lambda mo: dict[mo.string[mo.start():mo.end()]], text)
#
# You may combine both the dictionnary and search-and-replace
# into a single object using a 'callable' dictionary wrapper
# which can be directly used as a callback object.
#
# In Python 2.2+ you may extend the 'dictionary' built-in class instead
from UserDict import UserDict
class Xlator(UserDict):
""" An all-in-one multiple string substitution class """
def _make_regex(self):
""" Build a regular expression object based on the keys of
the current dictionary """
return re.compile("(%s)" % "|".join(map(re.escape, self.keys())))
def __call__(self, mo):
""" This handler will be invoked for each regex match """
# Count substitutions
self.count += 1 # Look-up string
return self[mo.string[mo.start():mo.end()]]
def xlat(self, text):
""" Translate text, returns the modified text. """
# Reset substitution counter
self.count = 0
# Process text
return self._make_regex().sub(self, text)
#
# Test
#
if __name__ == "__main__":
text = "Larry Wall is the creator of Perl"
dict = {
"Larry Wall" : "Guido van Rossum",
"creator" : "Benevolent Dictator for Life",
"Perl" : "Python",
}
print multiple_replace(dict, text)
xlat = Xlator(dict)
print xlat.xlat(text)
print "Changed %d thing(s)" % xlat.count
