Class: HeadMusic::Rudiment::Mode

Inherits:
QualifiedDiatonicContext show all
Defined in:
lib/head_music/rudiment/mode.rb

Overview

Represents a musical mode (church modes)

Constant Summary collapse

MODES = 
%i[ionian dorian phrygian lydian mixolydian aeolian locrian].freeze
RELATIVE_MAJOR_SEMITONES_BELOW_TONIC =

Semitones from a mode’s tonic down to its relative major tonic. Ionian is omitted because its own tonic spelling is the relative major.

{
  dorian: -2, phrygian: -4, lydian: -5,
  mixolydian: -7, aeolian: -9, locrian: -11
}.freeze
PARALLEL_QUALITIES =

The major or minor quality of each mode’s parallel key.

{
  ionian: :major, dorian: :minor, phrygian: :minor, lydian: :major,
  mixolydian: :major, aeolian: :minor, locrian: :minor
}.freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

This class inherits a constructor from HeadMusic::Rudiment::QualifiedDiatonicContext

Instance Attribute Details

#alias_name_keys ⇒ Object (readonly) Originally defined in module Named

Returns the value of attribute alias_name_keys.

#name_key ⇒ Object (readonly) Originally defined in module Named

Returns the value of attribute name_key.

Class Method Details

.default_qualifier ⇒ Object 



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# File 'lib/head_music/rudiment/mode.rb', line 8

def self.default_qualifier
  :ionian
end

.invalid_qualifier_message ⇒ Object 



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# File 'lib/head_music/rudiment/mode.rb', line 16

def self.invalid_qualifier_message
  "Mode must be one of: #{MODES.join(", ")}"
end

.valid_qualifiers ⇒ Object 



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# File 'lib/head_music/rudiment/mode.rb', line 12

def self.valid_qualifiers
  MODES
end

Instance Method Details

#parallel ⇒ Object 



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# File 'lib/head_music/rudiment/mode.rb', line 43

def parallel
  quality = PARALLEL_QUALITIES[mode_name]
  return unless quality

  HeadMusic::Rudiment::Key.get("#{tonic_spelling} #{quality}")
end

#relative ⇒ Object 



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# File 'lib/head_music/rudiment/mode.rb', line 39

def relative
  relative_major
end

#relative_major ⇒ Object 



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# File 'lib/head_music/rudiment/mode.rb', line 35

def relative_major
  HeadMusic::Rudiment::Key.get("#{relative_major_tonic_spelling} major")
end

#relative_major_tonic_spelling ⇒ Object (private) 



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

def relative_major_tonic_spelling
  return tonic_spelling if mode_name == :ionian

  offset = RELATIVE_MAJOR_SEMITONES_BELOW_TONIC[mode_name]
  relative_pitch = tonic_pitch + offset if offset
  # An unrecognized mode leaves relative_pitch nil, raising NoMethodError (preserved behavior).
  relative_pitch.spelling
end