/RomanNumerals

A library for evaluating Roman numerals, and translate between Roman symbols and other symbols

Primary LanguageJava

INSRUCTIONS TO RUN

  1. unzip galaxy.zip
  2. cd galaxy/
  3. ant
  4. java -cp galaxy.jar com.galaxy.GalaxyApp <path to input file>

PROGRAM DESIGN

  1. class design

     |- Symbol
     |- GalaxySymbol
     |- RomanSymbol
 |- Number
     |- GalaxyNumber
     |- RomanNumber
 |- NumberBuilder
     |- GalaxyNumberBuilder
     |- RomanNumberBuilder
 |- NumberParser
     |- BaseNumberParser
 |- ParseRule
     |- BaseDisjunctiveRule
         |- DescendingRule
         |- RepeatableRule
         |- SubtractableRule
 |- NumberBuilderFactory
 |- GalaxyNotesParser
 |- MetalPriceCalculator
    • Symbol classes: symbols with the number systems; also encodes the rules for conversion btw them
    • Number classes: immutable classes for the numbers, no direct instantiation is allowed
    • NumberParser classes: generic class to encode the algorithm for parsing the numbers
    • NumberBuilder classes: generic class to build the numbers; numbers are only allowed to be created via builder
    • ParserRule classes: encodes the parsing rules; the rules can be disjunctive or conjunctive
    • NumberBuilderFactory class: factory class to create builders
    • GalaxyNotesParser class: I/O supported

  2. algorithm for parsing roman numerals:

    • O(n) complexity; makes use of stack for storing intermediate results in processing loop

  3. rationale behind:

    • By restricting the creation of numbers to builders, we can encapsulate rules properly for the number system
    • By restricting the creation of builders to NumberBuilderFactory, we can control the proper initialization of them
    • By using generic NumberParser classes, we are able to abstract common parsing logic for different numerals
    • By using ParseRule classes, we can use different set of rules for different numeral systems, making it easy to extend

  4. more:

    • please refer to the code and documentations.