Class: HeadMusic::Style::Guide

Inherits:
Object
  • Object
show all
Defined in:
lib/head_music/style/guide.rb

Overview

Lookup facade for the guides in HeadMusic::Style::Guides. A class with a .get factory, matching Tradition and the gem’s other .get definers – no module in the gem defines .get. Never instantiated; .get returns a guide class or a Guides::Configured, either of which answers analyze(voice), key, category, and display_name.

Constant Summary collapse

GUIDE_CLASSES = 
[
  HeadMusic::Style::Guides::FuxCantusFirmus,
  HeadMusic::Style::Guides::SalzerSchachterCantusFirmus,
  HeadMusic::Style::Guides::DiatonicMelody,
  HeadMusic::Style::Guides::FirstSpeciesMelody,
  HeadMusic::Style::Guides::FirstSpeciesHarmony,
  HeadMusic::Style::Guides::SecondSpeciesMelody,
  HeadMusic::Style::Guides::SecondSpeciesHarmony,
  HeadMusic::Style::Guides::ThirdSpeciesMelody,
  HeadMusic::Style::Guides::ThirdSpeciesHarmony,
  HeadMusic::Style::Guides::ThirdSpeciesTripleMeterMelody,
  HeadMusic::Style::Guides::ThirdSpeciesTripleMeterHarmony,
  HeadMusic::Style::Guides::FourthSpeciesMelody,
  HeadMusic::Style::Guides::FourthSpeciesHarmony,
  HeadMusic::Style::Guides::CombinedFirstSecondThirdSpeciesMelody,
  HeadMusic::Style::Guides::CombinedFirstSecondThirdSpeciesHarmony,
  HeadMusic::Style::Guides::FifthSpeciesMelody,
  HeadMusic::Style::Guides::FifthSpeciesHarmony
].freeze
CONTOUR_CONFIGURATIONS =

The six preserved contour keys, literal and greppable. This table is the reason the registry is an explicit list: no inherited hook or constant scan can produce a registry entry that is an instance rather than a class.

{
  "arch_contour_melody" => {contour: :arch, minimum_melodic_intervals: 2},
  "ascending_contour_melody" => {contour: :ascending, minimum_melodic_intervals: 1},
  "descending_contour_melody" => {contour: :descending, minimum_melodic_intervals: 1},
  "static_contour_melody" => {contour: :static},
  "valley_contour_melody" => {contour: :valley, minimum_melodic_intervals: 2},
  "wave_contour_melody" => {contour: :wave, minimum_melodic_intervals: 2}
}.freeze
REGISTRY = 
GUIDE_CLASSES.to_h { |guide_class| [guide_class.key, guide_class] }
.merge(CONTOUR_CONFIGURATIONS.transform_values { |options|
  HeadMusic::Style::Guides::ContourMelody.with(**options)
}).freeze
ALL = 
REGISTRY.values.freeze

Class Method Summary collapse

Class Method Details

.all ⇒ Object 



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# File 'lib/head_music/style/guide.rb', line 81

def self.all
  ALL
end

.display_name_for(key) ⇒ Object 



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# File 'lib/head_music/style/guide.rb', line 93

def self.display_name_for(key)
  I18n.translate(
    key,
    scope: "head_music.style.guides",
    default: key.to_s.tr("_", " ").split.map(&:capitalize).join(" ")
  )
end

.get(key) ⇒ Object

A miss returns nil rather than falling back, unlike Tradition.get: a substituted tradition changes a consonance default, but a substituted guide would silently grade a voice against the wrong ruleset.

Deliberately a plain hash lookup. Utilities::HashKey.for would memoize an entry per distinct argument, and these keys arrive from a consumer’s database; const_get would traverse namespaces and raise NameError on an invalid name, violating nil-on-miss.



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# File 'lib/head_music/style/guide.rb', line 63

def self.get(key)
  return key if key.respond_to?(:analyze)

  REGISTRY[key.to_s]
end

.get!(key) ⇒ Object 



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# File 'lib/head_music/style/guide.rb', line 69

def self.get!(key)
  get(key) || raise(KeyError, "unknown style guide: #{key.inspect}")
end

.key_for(guide) ⇒ Object 



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# File 'lib/head_music/style/guide.rb', line 89

def self.key_for(guide)
  REGISTRY.key(guide)
end

.keys ⇒ Object 



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# File 'lib/head_music/style/guide.rb', line 85

def self.keys
  REGISTRY.keys
end

.known?(key) ⇒ Boolean

Asks whether the registry knows this, not whether it quacks like a guide. Delegating to .get would answer true for any analyze-responder, including an ad-hoc configuration whose key_for is nil – so known? and key_for would disagree about the same object.

Returns:

  • (Boolean) 


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# File 'lib/head_music/style/guide.rb', line 77

def self.known?(key)
  REGISTRY.key?(key.to_s) || !key_for(key).nil?
end