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. Never instantiated; .get returns a guide class or a Guides::Configured, either of which answers assess(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::FirstThreeSpeciesMelody,
  HeadMusic::Style::Guides::FirstThreeSpeciesHarmony,
  HeadMusic::Style::Guides::FifthSpeciesMelody,
  HeadMusic::Style::Guides::FifthSpeciesHarmony
].freeze
CONTOUR_CONFIGURATIONS =

Why the registry is an explicit list: no inherited hook or constant scan can produce an 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
LEAF_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
COMPOSITE_MEMBERS =

A species is a melody guide and a harmony guide, and which two make up third species is counterpoint pedagogy rather than a consumer’s configuration. Registered so a consumer asks for “third_species” and gets one grade back.

{
  "first_species" => %w[first_species_melody first_species_harmony],
  "second_species" => %w[second_species_melody second_species_harmony],
  "third_species" => %w[third_species_melody third_species_harmony],
  "third_species_triple_meter" => %w[third_species_triple_meter_melody third_species_triple_meter_harmony],
  "fourth_species" => %w[fourth_species_melody fourth_species_harmony],
  "fifth_species" => %w[fifth_species_melody fifth_species_harmony],
  "first_three_species" => %w[first_three_species_melody first_three_species_harmony]
}.freeze
REGISTRY =

Two passes, because a composite names entries the first pass built. Merged over LEAF_REGISTRY rather than over REGISTRY, which does not exist yet.

fetch, so a member renamed in Guides takes the gem down on require rather than leaving a species holding half a ruleset.

LEAF_REGISTRY.merge(
  COMPOSITE_MEMBERS.transform_values { |keys|
    HeadMusic::Style::Guides::CompositeGuide.new(keys.map { |key| LEAF_REGISTRY.fetch(key) })
  }
).freeze
ALL = 
REGISTRY.values.freeze
PLURAL_GAPS =

An unfillable template is invisible until someone reads it, so every string is asked for here. Holds the keys whose plural forms the locale data lacks.

HeadMusic::Style::Template.verify!(ALL).freeze

Class Method Summary collapse

Class Method Details

.all ⇒ Object 



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# File 'lib/head_music/style/guide.rb', line 95

def self.all
  ALL
end

.display_name_for(key) ⇒ Object 



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# File 'lib/head_music/style/guide.rb', line 107

def self.display_name_for(key)
  I18n.translate(
    "#{key}.name",
    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 guide would grade a voice against the wrong ruleset.

A plain hash lookup: HashKey.for would memoize per distinct argument and these keys arrive from a consumer’s database. The pass-through checks assess_items because guidelines answer assess too, with other arguments.



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# File 'lib/head_music/style/guide.rb', line 79

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

  REGISTRY[key.to_s]
end

.get!(key) ⇒ Object 



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

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

.instruction_for(key) ⇒ Object 



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# File 'lib/head_music/style/guide.rb', line 115

def self.instruction_for(key)
  HeadMusic::Style::Template.render("guides.#{key}.instruction")
end

.key_for(guide) ⇒ Object 



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# File 'lib/head_music/style/guide.rb', line 103

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

.keys ⇒ Object 



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# File 'lib/head_music/style/guide.rb', line 99

def self.keys
  REGISTRY.keys
end

.known?(key) ⇒ Boolean

Not delegated to .get, which would answer true for any assess_items responder – leaving known? and key_for disagreeing about the same object.

Returns:

  • (Boolean) 


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# File 'lib/head_music/style/guide.rb', line 91

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