Class: HeadMusic::Rudiment::Alteration

Inherits:
Object
  • Object
show all
Includes:
Comparable
Defined in:
lib/head_music/rudiment/alteration.rb

Overview

An Alteration is a symbol that modifies pitch, such as a sharp, flat, or natural. In French, sharps and flats in the key signature are called “altérations”.

Constant Summary collapse

ALTERATION_RECORDS = 
[
  {
    identifier: :sharp, cents: 100,
    symbols: [{ascii: "#", unicode: "♯", html_entity: "♯"}]
  },
  {
    identifier: :flat, cents: -100,
    symbols: [{ascii: "b", unicode: "♭", html_entity: "♭"}]
  },
  {
    identifier: :natural, cents: 0,
    symbols: [{ascii: "", unicode: "♮", html_entity: "♮"}]
  },
  {
    identifier: :double_sharp, cents: 200,
    symbols: [{ascii: "x", unicode: "𝄪", html_entity: "𝄪"}]
  },
  {
    identifier: :double_flat, cents: -200,
    symbols: [{ascii: "bb", unicode: "𝄫", html_entity: "𝄫"}]
  }
].freeze
ALTERATION_IDENTIFIERS = 
ALTERATION_RECORDS.map { |attributes| attributes[:identifier] }.freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(attributes) ⇒ Alteration (private)

Returns a new instance of Alteration.



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# File 'lib/head_music/rudiment/alteration.rb', line 102

def initialize(attributes)
  @identifier = attributes[:identifier]
  @cents = attributes[:cents]
  initialize_musical_symbols(attributes[:symbols])
end

Instance Attribute Details

#cents ⇒ Object (readonly)

Returns the value of attribute cents.



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# File 'lib/head_music/rudiment/alteration.rb', line 11

def cents
  @cents
end

#identifier ⇒ Object (readonly)

Returns the value of attribute identifier.



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# File 'lib/head_music/rudiment/alteration.rb', line 11

def identifier
  @identifier
end

#musical_symbols ⇒ Object (readonly)

Returns the value of attribute musical_symbols.



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# File 'lib/head_music/rudiment/alteration.rb', line 11

def musical_symbols
  @musical_symbols
end

Class Method Details

.all ⇒ Object 



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# File 'lib/head_music/rudiment/alteration.rb', line 40

def self.all
  ALTERATION_RECORDS.map { |attributes| new(attributes) }
end

.by(key, value) ⇒ Object 



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# File 'lib/head_music/rudiment/alteration.rb', line 64

def self.by(key, value)
  all.detect do |alteration|
    alteration.send(key) == value if %i[cents semitones].include?(key.to_sym)
  end
end

.get(identifier) ⇒ Object 



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# File 'lib/head_music/rudiment/alteration.rb', line 56

def self.get(identifier)
  return identifier if identifier.is_a?(HeadMusic::Rudiment::Alteration)

  all.detect do |alteration|
    alteration.representions.include?(identifier)
  end
end

.matcher ⇒ Object 



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# File 'lib/head_music/rudiment/alteration.rb', line 48

def self.matcher
  @matcher ||= Regexp.new symbols.join("|")
end

.symbol?(candidate) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/head_music/rudiment/alteration.rb', line 52

def self.symbol?(candidate)
  candidate =~ /^(#{matcher})$/
end

.symbols ⇒ Object 



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# File 'lib/head_music/rudiment/alteration.rb', line 44

def self.symbols
  @symbols ||= all.map { |alteration| [alteration.ascii, alteration.unicode] }.flatten.reject { |s| s.nil? || s.empty? }
end

Instance Method Details

#<=>(other) ⇒ Object 



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# File 'lib/head_music/rudiment/alteration.rb', line 91

def <=>(other)
  other = HeadMusic::Rudiment::Alteration.get(other)
  cents <=> other.cents
end

#initialize_musical_symbols(list) ⇒ Object (private) 



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# File 'lib/head_music/rudiment/alteration.rb', line 108

def initialize_musical_symbols(list)
  @musical_symbols = (list || []).map do |record|
    HeadMusic::Rudiment::MusicalSymbol.new(
      unicode: record[:unicode],
      ascii: record[:ascii],
      html_entity: record[:html_entity]
    )
  end
end

#musical_symbol ⇒ Object 



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# File 'lib/head_music/rudiment/alteration.rb', line 96

def musical_symbol
  musical_symbols.first
end

#name ⇒ Object 



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# File 'lib/head_music/rudiment/alteration.rb', line 70

def name
  identifier.to_s.tr("_", " ")
end

#representions ⇒ Object 



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# File 'lib/head_music/rudiment/alteration.rb', line 74

def representions
  [identifier, identifier.to_s, name, ascii, unicode, html_entity]
    .reject { |representation| representation.to_s.strip == "" }
end

#semitones ⇒ Object 



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# File 'lib/head_music/rudiment/alteration.rb', line 79

def semitones
  cents / 100.0
end

#to_s ⇒ Object 



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# File 'lib/head_music/rudiment/alteration.rb', line 87

def to_s
  unicode
end