Class: AStar

Inherits:
Path show all
Defined in:
lib/delve/path/astar.rb

Instance Method Summary collapse

Constructor Details

#initialize(to_x, to_y, free_checker, options = Hash.new) ⇒ AStar

Returns a new instance of AStar.



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# File 'lib/delve/path/astar.rb', line 5

def initialize(to_x, to_y, free_checker, options = Hash.new)
  super to_x, to_y, free_checker, options

  @todo = Array.new
  @done = Hash.new
  @from_x = nil
  @from_y = nil
end

Instance Method Details

#compute(from_x, from_y) ⇒ Object 



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# File 'lib/delve/path/astar.rb', line 14

def compute(from_x, from_y)
  raise 'Cannot compute path without a block' unless block_given?

  @todo = Array.new
  @done = Hash.new
  @from_x = from_x
  @from_y = from_y
  add @to_x, @to_y, nil

  while @todo.length > 0
    item = @todo.shift
    break if item[:x] == from_x and item[:y] == from_y
    neighbours = get_neighbours item[:x], item[:y]

    (0..neighbours.length-1).each do |i|
      neighbour = neighbours[i]
      x = neighbour[0]
      y = neighbour[1]
      id = "#{x},#{y}"
      next if @done.include? id
      add x, y, item
    end
  end

  item = @done["#{from_x},#{from_y}"]
  return nil if item.nil?

  until item.nil?
    yield item[:x], item[:y]
    item = item[:prev]
  end
end