Contents

# frozen_string_literal: true

# A pitch class is a set of pitches separated by octaves.
class HeadMusic::PitchClass
  include Comparable

  attr_reader :number
  attr_reader :spelling

  SHARP_SPELLINGS = %w[C C# D D# E F F# G G# A A# B].freeze
  FLAT_SPELLINGS = %w[C Db D Eb E F Gb G Ab A Bb B].freeze
  INTEGER_NOTATION = %w[0 1 2 3 4 5 6 7 8 9 t e].freeze

  def self.get(identifier)
    @pitch_classes ||= {}
    if HeadMusic::Spelling.matching_string(identifier)
      spelling = HeadMusic::Spelling.get(identifier)
      number = spelling.pitch_class.to_i
    end
    number ||= identifier.to_i % 12
    @pitch_classes[number] ||= new(number)
  end

  class << self
    alias [] get
  end

  def initialize(pitch_class_or_midi_number)
    @number = pitch_class_or_midi_number.to_i % 12
  end

  def to_i
    number
  end

  def to_integer_notation
    INTEGER_NOTATION[number]
  end

  def sharp_spelling
    SHARP_SPELLINGS[number]
  end

  def flat_spelling
    FLAT_SPELLINGS[number]
  end

  # Pass in the number of semitones
  def +(other)
    HeadMusic::PitchClass.get(to_i + other.to_i)
  end

  # Pass in the number of semitones
  def -(other)
    HeadMusic::PitchClass.get(to_i - other.to_i)
  end

  def ==(other)
    to_i == other.to_i
  end
  alias enharmonic? ==

  def <=>(other)
    to_i <=> other.to_i
  end

  def intervals_to(other)
    delta = other.to_i - to_i
    inverse = delta.positive? ? delta - 12 : delta + 12
    [delta, inverse].sort_by(&:abs).map { |interval| HeadMusic::ChromaticInterval.get(interval) }
  end

  def smallest_interval_to(other)
    intervals_to(other).first
  end

  def white_key?
    [0, 2, 4, 5, 7, 9, 11].include?(number)
  end

  def black_key?
    !white_key?
  end

  private_class_method :new
end

Version data entries

5 entries across 5 versions & 1 rubygems

Version	Path
head_music-0.23.4	lib/head_music/pitch_class.rb
head_music-0.23.3	lib/head_music/pitch_class.rb
head_music-0.23.2	lib/head_music/pitch_class.rb
head_music-0.23.1	lib/head_music/pitch_class.rb
head_music-0.23.0	lib/head_music/pitch_class.rb