Module: Yzz::Side

Included in:
NegwardSide, PoswardSide
Defined in:
lib/yzz/side.rb

Overview

Ted Nelson calls objects in a ZZ structure ‘cells’ and defines that each cell has exactly two sides, posward side and negward side, along each dimension. This is represented by Yzz::Side class here.

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#neighbor ⇒ Object (readonly)

Returns the value of attribute neighbor.



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# File 'lib/yzz/side.rb', line 6

def neighbor
  @neighbor
end

Instance Method Details

#crossover(new_neighbor) ⇒ Object Also known as: *

Sets a new neighboor, crossing over the conflicting link, if present, with the old neighbor.



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# File 'lib/yzz/side.rb', line 46

def crossover new_neighbor
  return unlink if new_neighbor.nil?
  fail TypeError, "Zz object or nil expected!" unless new_neighbor.is_a_zz?
  conflicter = opposite_side( of: new_neighbor ).neighbor
  return new_neighbor if conflicter == self # no neighbor change
  begin # TODO: Should be an atomic transaction
    old_neighbor = set_neighbor! new_neighbor
    opposite_side( of: new_neighbor ).set_neighbor! zz
    same_side( of: conflicter ).set_neighbor! old_neighbor # cross over
    opposite_side( of: old_neighbor ).set_neighbor! conflicter # cross over
  end
  return old_neighbor
end

#dimension ⇒ Object

Reader #dimension delegates to the class, relying on parametrized subclassing.



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# File 'lib/yzz/side.rb', line 15

def dimension; self.class.dimension end

#initialize(neighbor: nil) ⇒ Object

The constructor has one optional named parameter :neighbor.



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# File 'lib/yzz/side.rb', line 19

def initialize neighbor: nil
  set_neighbor! neighbor
end

#inspect ⇒ Object

Inspect string of the instance.



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# File 'lib/yzz/side.rb', line 71

def inspect
  to_s
end

#link(new_neighbor) ⇒ Object Also known as: <<

Links a new neighbor, unlinking and returning the old one. Cares about the argument type (a Yzz descendant or nil), and cares not to break the new neighbor’s conflicting connectivity, if any.



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# File 'lib/yzz/side.rb', line 27

def link new_neighbor
  return unlink if new_neighbor.nil?
  fail TypeError, "Yzz object or nil expected!" unless new_neighbor.is_a_zz?
  conflicter = opposite_side( of: new_neighbor ).neighbor # have concerns
  return new_neighbor if conflicter == self               # no neighbor change
  fail TypeError, "Suggested new neighbor (#{new_neighbor}) already " +
    "has a conflicting #{opposite_direction} link along dimension " +
    "#{dimension}!" if conflicter.is_a_zz?
  begin # TODO: Should be an atomic transaction
    old_neighbor = set_neighbor! new_neighbor
    opposite_side( of: new_neighbor ).set_neighbor! zz
  end
  return old_neighbor
end

#unlink ⇒ Object

Unlinks the neighbor, returning it.



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# File 'lib/yzz/side.rb', line 63

def unlink
  unlink!.tap do |neighbor|
    opposite_side( of: neighbor ).unlink! if neighbor.is_a_zz?
  end
end

#zz ⇒ Object

Reader #zz delegates to the class, relying on parametrized subclassing.



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# File 'lib/yzz/side.rb', line 10

def zz; self.class.zz end