Class: Bocadillo::Cover

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

Class Method Summary collapse

Class Method Details

.cover(arr = [], x0 = 0, y = 0, l = nil) ⇒ Object 



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# File 'lib/bocadillo/cover.rb', line 2

def self.cover(arr = [], x0 = 0, y = 0, l = nil)
  l = arr.length if l.nil?
  # Check bad input
  if x0 >= l
    # Error: past assigned slice
    return false
  end
  if x0 > arr.length - 1
    # Error: past array length
    return false;
  end

  if y > arr[x0].length - 1
    if x0 === l - 1
      # Termination of rightmost string
      return [nil]
    end
    # The string at x0 was only as long as y0, so call on the next item
    return [nil].concat(self.cover(arr, x0 + 1, y, l))
  end

  # Initialize non-trivial return structure
  u = {
    'l' => arr[x0][y],
    'c' => []
  }
  r = [u]

  # Spread in width until we find either the end, or a different char
  x = x0
  loop do
    m = false
    if x < l && arr[x0][y] === arr[x][y]
      m = true 
      x += 1
    end
    break unless m
  end

  # If we haven't covered the full length of the assigned slice, launch
  # on the pair (x + 1, y0) with the original length l.
  if x < l
    r.concat(self.cover(arr, x, y, l))
  end

  # Launch on the tail of the string at s[x0] from the position y
  u['c'].concat(self.cover(arr, x0, y + 1, x))

  r
end