# romanNumerals.py # # Copyright (c) 2006, 2019, Paul McGuire # import pyparsing as pp def romanNumeralLiteral(numeralString, value): return pp.Literal(numeralString).setParseAction(pp.replaceWith(value)) one = romanNumeralLiteral("I", 1) four = romanNumeralLiteral("IV", 4) five = romanNumeralLiteral("V", 5) nine = romanNumeralLiteral("IX", 9) ten = romanNumeralLiteral("X", 10) forty = romanNumeralLiteral("XL", 40) fifty = romanNumeralLiteral("L", 50) ninety = romanNumeralLiteral("XC", 90) onehundred = romanNumeralLiteral("C", 100) fourhundred = romanNumeralLiteral("CD", 400) fivehundred = romanNumeralLiteral("D", 500) ninehundred = romanNumeralLiteral("CM", 900) onethousand = romanNumeralLiteral("M", 1000) numeral = ( onethousand | ninehundred | fivehundred | fourhundred | onehundred | ninety | fifty | forty | ten | nine | five | four | one ).leaveWhitespace() romanNumeral = numeral[1, ...].setParseAction(sum) # unit tests def makeRomanNumeral(n): def addDigits(n, limit, c, s): while n >= limit: n -= limit s += c return n, s ret = "" n, ret = addDigits(n, 1000, "M", ret) n, ret = addDigits(n, 900, "CM", ret) n, ret = addDigits(n, 500, "D", ret) n, ret = addDigits(n, 400, "CD", ret) n, ret = addDigits(n, 100, "C", ret) n, ret = addDigits(n, 90, "XC", ret) n, ret = addDigits(n, 50, "L", ret) n, ret = addDigits(n, 40, "XL", ret) n, ret = addDigits(n, 10, "X", ret) n, ret = addDigits(n, 9, "IX", ret) n, ret = addDigits(n, 5, "V", ret) n, ret = addDigits(n, 4, "IV", ret) n, ret = addDigits(n, 1, "I", ret) return ret # make a string of all roman numerals from I to MMMMM tests = " ".join(makeRomanNumeral(i) for i in range(1, 5000 + 1)) # parse each roman numeral, and populate map for validation below roman_int_map = {} for expected, (t, s, e) in enumerate(romanNumeral.scanString(tests), start=1): orig = tests[s:e] if t[0] != expected: print("{} {} {}".format("==>", t, orig)) roman_int_map[orig] = t[0] def verify_value(s, tokens): expected = roman_int_map[s] if tokens[0] != expected: raise Exception( "incorrect value for {} ({}), expected {}".format(s, tokens[0], expected) ) romanNumeral.runTests( """\ XVI XXXIX XIV XIX MCMLXXX MMVI MMMMM """, fullDump=False, postParse=verify_value, )