Method: LifeCalculator#neighbors

Defined in:
lib/life_game_viewer/model/life_calculator.rb

#neighbors(model, row, col) ⇒ Object

Returns an array of [row, col] tuples corresponding to the cells neighboring the specified cell location. “Neighbor” is defined as a cell with up/down/left/right/diagonal adjacency to the specified cell.



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# File 'lib/life_game_viewer/model/life_calculator.rb', line 27

def neighbors(model, row, col)

  neighbors = []

  at_left_edge   = col == 0
  at_right_edge  = col == model.column_count - 1
  at_top_edge    = row == 0
  at_bottom_edge = row == model.row_count - 1

  col_to_left  = col - 1
  col_to_right = col + 1
  row_above    = row - 1
  row_below    = row + 1

  # In its own row, return the cell to the left and right as possible.
  unless at_left_edge
    neighbors << [row, col_to_left]
  end
  unless at_right_edge
    neighbors << [row, col_to_right]
  end

  # Process the row above
  unless at_top_edge
    unless at_left_edge
      neighbors << [row_above, col_to_left]
    end
    neighbors << [row_above, col]
    unless at_right_edge
      neighbors << [row_above, col_to_right]
    end
  end

  # Process the row below
  unless at_bottom_edge
    unless at_left_edge
      neighbors << [row_below, col_to_left]
    end
    neighbors << [row_below, col]
    unless at_right_edge
      neighbors << [row_below, col_to_right]
    end
  end

  neighbors

end