gistfile1.py

# Question 7: Find and Replace

# For this question you need to define two procedures:
#  make_converter(match, replacement)
#     Takes as input two strings and returns a converter. It doesn't have
#     to make a specific type of thing. Itcan 
#     return anything you would find useful in apply_converter.
#  apply_converter(converter, string)
#     Takes as input a converter (produced by create_converter), and 
#     a string, and returns the result of applying the converter to the 
#     input string. This replaces all occurrences of the match used to 
#     build the converter, with the replacement.  It keeps doing 
#     replacements until there are no more opportunities for replacements.


def make_converter(match, replacement):
     return match, replacement


def apply_converter(converter, string):
     match = converter[0]
     replacement = converter[1]
     madeReplacement = True
     while madeReplacement:
          madeReplacement = False
          #pos = 0
          for pos in range(0, len(string) - len(replacement)):
               print "hello world1"
               if match == True:
                    print "hello world2"
                    currentString = currentString.split(0, position)
                    + replacement
                    + currentString.split(position+len(toMatch)-1, len(currentString)-1)
                    madeReplacement = True
                    print currentString


# For example,

c1 = make_converter('aa', 'a')
print apply_converter(c1, 'aaaa')
#>>> a

c = make_converter('aba', 'b')
print apply_converter(c, 'aaaaaabaaaaa')
#>>> ab

# Note that this process is not guaranteed to terminate for all inputs
# (for example, apply_converter(make_converter('a', 'aa'), 'a') would 
# run forever).