Class: PatternExpander

Inherits:
Object
  • Object
show all
Defined in:
lib/patternexpander.rb

Overview

This class is used for an experimental feature that allows specifying repeats inside of individual patterns, instead of the song flow. This feature is currently disabled, so for the time being this class is dead code.

TODO: The expand_pattern method in this class should probably be moved to the Pattern class. This class would then go away.

Constant Summary collapse

BARLINE = 
"|"
TICK = 
"-"
REPEAT_FRAME_REGEX = 
/:[-]*:[0-9]*/
NUMBER_REGEX = 
/[0-9]+/

Class Method Summary collapse

Class Method Details

.expand_pattern(flow, pattern) ⇒ Object

TODO: What should happen if flow is longer than pattern? Either ignore extra flow, or add trailing .… to each track to match up?



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# File 'lib/patternexpander.rb', line 17

def self.expand_pattern(flow, pattern)
  unless self.valid_flow? flow
    raise InvalidFlowError, "Invalid flow"
  end
  
  flow = flow.delete(BARLINE)
  
  # Count number of :
  # If odd, then there's an implicit : at the beginning of the pattern.
  # TODO: What if the first character in the flow is already :
  #       That means repeat the first step twice, right?
  number_of_colons = flow.scan(/:/).length
  if number_of_colons % 2 == 1
    # TODO: What if flow[0] is not '-'
    flow[0] = ":"  # Make the implicit : at the beginning explicit
  end
  
  repeat_frames = parse_flow_for_repeat_frames(flow)
  
  repeat_frames.reverse.each do |frame|
    pattern.tracks.each do |name, track|
      range = frame[:range]
      
      # WARNING: Don't change the three lines below to:
      #   track.rhythm[range] = whatever
      # When changing the rhythm like this, rhythm=() won't be called,
      # and Track.beats won't be updated as a result.
      new_rhythm = track.rhythm
      new_rhythm[range] = new_rhythm[range] * frame[:repeats]
      track.rhythm = new_rhythm
    end
  end
  
  return pattern
end

.valid_flow?(flow) ⇒ Boolean

TODO: Return more specific info on why flow isn’t valid

Returns:

  • (Boolean) 


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# File 'lib/patternexpander.rb', line 54

def self.valid_flow?(flow)
  flow = flow.delete(BARLINE)
  flow = flow.delete(TICK)
  
  # If flow contains any characters other than : and [0-9], it's invalid.
  if flow.match(/[^:0-9]/) != nil
    return false
  end
  
  # If flow contains nothing but :, it's always valid.
  if flow == ":" * flow.length
    return true
  end
  
  # If flow DOESN'T contain a :, it's not valid.
  if flow.match(/:/) == nil
    return false
  end
  
  segments = flow.split(/[0-9]+/)
  
  # Ignore first segment
  segments[1...segments.length].each do |segment|
    if segment.length % 2 == 1
      return false
    end
  end
  
  return true
end