Class: Text::Format::Roman

Inherits:
Object
  • Object
show all
Defined in:
lib/text/format/roman.rb

Overview

Provides a numbering object that will produce numbers. Accepts three parameters for numbering that will control how the numbers are presented when given as #[](index).

:offset

The number to add to the index in order to produce the proper index. This is because #tag_text indexes from 0, not 1. This defaults to 1. Any value less than 1 will be set to 1 (because Romans did not know about zero or negative numbers).

:lower

Renders the Roman numerals in lowercase if true. Defaults to false.

:postfix

The value that will be appended to the number presented by #[]. Defaults to nil.

:prefix

The value that will be prepended to the number presented by #[]. Defaults to nil.

r1 = Text::Format::Roman.new(:postfix => ".")
puts r1[0]  # => "I."
puts r1[8]  # => "IX.

r2 = Text::Format::Roman.new(:prefix => "M.")
puts r2[0]  # => "M.I"
puts r2[8]  # => "M.IX"

r3 = Text::Format::Roman.new(:offset => 3)
puts r3[0]  # => "III"
puts r3[9]  # => "XII"

r4 = Text::Format::Roman.new(:offset => 0)
puts r4[0]  # => "I"
puts r4[8]  # => "IX"

r5 = Text::Format::Roman.new(:lower => true)
puts r5[0]  # => "i"
puts r5[8]  # => "ix"

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Roman

Returns a new instance of Roman.



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# File 'lib/text/format/roman.rb', line 97

def initialize(options = {})
  @offset   = options[:offset].to_i || 1
  @lower    = options[:lower]       || false
  @postfix  = options[:postfix]     || nil
  @prefix   = options[:prefix]      || nil

  @offset   = 1 if @offset < 1
end

Instance Method Details

#[](index) ⇒ Object 



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# File 'lib/text/format/roman.rb', line 37

def [](index)
  roman = ""
  index += @offset

    # Do 1,000s
  roman << "M" * (index / 1000)
  index %= 1000

    # Do 900s
  roman << "CM" * (index / 900)
  index %= 900

    # Do 500s
  roman << "D" * (index / 500)
  index %= 500

    # Do 400s
  roman << "CD" * (index / 400)
  index %= 400

    # Do 100s
  roman << "C" * (index / 100)
  index %= 100

    # Do 90s
  roman << "XC" * (index / 90)
  index %= 90

    # Do 50s
  roman << "L" * (index / 50)
  index %= 50

    # Do 40s
  roman << "XL" * (index / 40)
  index %= 40

    # Do 10s
  roman << "X" * (index / 10)
  index %= 10

    # Do 9s
  roman << "IX" * (index / 9)
  index %= 9

    # Do 5s
  roman << "V" * (index / 5)
  index %= 5

    # Do 4s
  roman << "IV" * (index / 4)
  index %= 4

    # Do 1s
  roman << "I" * index

  roman.downcase! if @lower

  "#{@prefix}#{roman}#{@postfix}"
end