"""
Alternative dictionary module for the keypad entry problem.

Author: Rodney Topor
Date: November 2007
"""

import string

# # initialise offsets of lower case letters (there must be a better way!)
# offset = {}
# n = 0
# for c in string.lowercase:
#   offset[c] = n
#   n = n + 1
#
# mapping from letters to digits
# digit =   [
#                          '2', '2', '2',   '3', '3', '3', 
#         '4', '4', '4',   '5', '5', '5',   '6', '6', '6',
#   '7', '7',  '7', '7',   '8', '8', '8',   '9', '9', '9', '9'
# ]
# 
# to map word to corresponding digit sequence:
# digits = "".join([ digit[offset[c]] for c in word ])

# mapping from letters to digits
alpha_to_digits = 
    string.maketrans(string.lowercase, "22233344455566677778889999")

# mapping from digit sequences to lists of words
map = {}

STARS = "************"


def add_word(word):
    """Adds a word to the dictionary."""
    # compute digit sequence corresponding to word
    digits = word.translate(alpha_to_digits)
    
    # add word to the list of words for this digit sequence
    if (map.has_key(digits)):
        map[digits].append(word)
    else:
        map[digits] = [word]

        
def get_words(digits):
    """Returns the list of words associated with a digit sequence.""" 
    if (map.has_key(digits)):
        words = map[digits]
        if (len(words) == 1):
            return words[0]
        else:
            return words    
        return map[digits]
    else:
        return STARS[:len(digits)]
        
        
def test():
    add_word("foo")
    add_word("bar")
    print get_words('366')
    print get_words('227')
    
test()