Class: HeadMusic::Content::Voice::Continuity

Inherits:
Object
  • Object
show all
Defined in:
lib/head_music/content/voice/continuity.rb

Overview

Examines a voice’s placements for the first break in its coverage of time. A voice is continuous when its first placement starts a bar and every later placement begins where the one before it ends.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(composition, placements) ⇒ Continuity

Returns a new instance of Continuity.



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# File 'lib/head_music/content/voice/continuity.rb', line 8

def initialize(composition, placements)
  @composition = composition
  @placements = placements
end

Instance Attribute Details

#composition ⇒ Object (readonly)

Returns the value of attribute composition.



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# File 'lib/head_music/content/voice/continuity.rb', line 6

def composition
  @composition
end

#placements ⇒ Object (readonly)

Returns the value of attribute placements.



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# File 'lib/head_music/content/voice/continuity.rb', line 6

def placements
  @placements
end

Instance Method Details

#bar_start_position(placement) ⇒ Object (private) 



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# File 'lib/head_music/content/voice/continuity.rb', line 43

def bar_start_position(placement)
  HeadMusic::Content::Position.new(composition, placement.position.bar_number, 1, 0)
end

#first_gap ⇒ Object

Returns nil when the placements are contiguous, or [expected_position, found_placement] for the first gap.



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# File 'lib/head_music/content/voice/continuity.rb', line 15

def first_gap
  return if placements.empty?

  leading_gap || interior_gap
end

#interior_gap ⇒ Object (private) 



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# File 'lib/head_music/content/voice/continuity.rb', line 30

def interior_gap
  placements.each_cons(2) do |previous, current|
    expected_position = previous.next_position
    return [expected_position, current] unless current.position == expected_position
  end
  nil
end

#leading_gap ⇒ Object (private) 



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# File 'lib/head_music/content/voice/continuity.rb', line 23

def leading_gap
  first = placements.first
  return if starts_its_bar?(first)

  [bar_start_position(first), first]
end

#starts_its_bar?(placement) ⇒ Boolean (private)

Returns:

  • (Boolean) 


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# File 'lib/head_music/content/voice/continuity.rb', line 38

def starts_its_bar?(placement)
  position = placement.position
  position.count == 1 && position.tick.zero?
end