Class: HeadMusic::Notation::ABC::VoiceRegistry

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/head_music/notation/abc/voice_registry.rb

Overview

Owns the tune’s per-voice interpretation states and tracks which voice the body is currently writing into.

A tune may declare its voices in V: header fields, switch between them with V: body lines, or use neither — in which case all the music belongs to one unnamed voice.

Instance Method Summary collapse

Constructor Details

#initialize(composition, key_signature, duration_resolver) ⇒ VoiceRegistry

Returns a new instance of VoiceRegistry.



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# File 'lib/head_music/notation/abc/voice_registry.rb', line 12

def initialize(composition, key_signature, duration_resolver)
  @composition = composition
  @key_signature = key_signature
  @duration_resolver = duration_resolver
  @states = {}
end

Instance Method Details

#current ⇒ Object

Body music before any V: line falls into a default unnamed voice, created here on demand so a leading V: line doesn’t force an empty one into the composition.



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# File 'lib/head_music/notation/abc/voice_registry.rb', line 43

def current
  @current ||= state(nil)
end

#declare(roles, default:) ⇒ Object

Creates a state for each declared role, or — when nothing is declared and the body never switches voices — the single unnamed voice that tune uses, and makes the first of them current.



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# File 'lib/head_music/notation/abc/voice_registry.rb', line 26

def declare(roles, default:)
  roles.each { |role| state(role) }
  state(nil) if @states.empty? && default
  @current = @states.values.first
end

#each(&block) ⇒ Object 



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# File 'lib/head_music/notation/abc/voice_registry.rb', line 19

def each(&block)
  @states.each_value(&block)
end

#state(role) ⇒ Object 



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# File 'lib/head_music/notation/abc/voice_registry.rb', line 32

def state(role)
  @states[role] ||= VoiceState.new(
    @composition.add_voice(role: role),
    PitchBuilder.new(@key_signature),
    @duration_resolver
  )
end

#switch_to(role) ⇒ Object 



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# File 'lib/head_music/notation/abc/voice_registry.rb', line 47

def switch_to(role)
  @current = state(role)
end