class MoveTree

A tree structure for the possible moves of a chess piece.

Attributes

root[R]

Public Class Methods

new(root_position) click to toggle source

Assigns a MoveTreeNode to be the root.

@param [Array<Integer>] root_position An integer array of length 2 representing the starting location for a piece.

# File lib/chess_pieces/move_tree.rb, line 15
def initialize(root_position)
  @root = MoveTreeNode.new(root_position)
end

Public Instance Methods

clone() click to toggle source

Creates a deep copy of the move tree.

@return [MoveTree] A deep copy of self.

# File lib/chess_pieces/move_tree.rb, line 37
def clone
  Marshal.load(Marshal.dump(self))
end

each(&block) click to toggle source

Iterates through the tree using level order.

@param [Block or Proc] The block to call each node in the the tree on.

# File lib/chess_pieces/move_tree.rb, line 23
def each(&block)
  visit_queue = [@root]
  until visit_queue.empty?
    current_node = visit_queue.shift
    block.call(current_node)
    current_node.children.each { |child| visit_queue << child }
  end
  self
end

to_a() click to toggle source

Returns an array of the Move Tree using level order (for ease of writing test cases)

@return [Array<Array<Integer>>] tree_array The array of locations of the move tree.

# File lib/chess_pieces/move_tree.rb, line 75
def to_a
  tree_array = []
  each { |node| tree_array << node.loc }
  # Remove the root node since staying in the same location
  # is not a move.
  tree_array.shift
  tree_array
end

trim_branch!(loc) click to toggle source

Removes a node and its children from the MoveTree. Returns the trimmed child if it was found and nil if it wasn't found in the tree.

@param [Array<Integer>] loc A location array (2 integers) or a MoveTreeNode to remove from the the tree. @raise [ArgumentError] if loc is not an Array or MoveTreeNode.

# File lib/chess_pieces/move_tree.rb, line 48
def trim_branch!(loc)
  # Raise an error if the argument is not either an array or a MoveTreeNode
  unless (loc.is_a? Array) || (loc.is_a? MoveTreeNode)
    raise(ArgumentError, "Argument is a #{loc.class}; should be Array or MoveTreeNode")
  end

  # Convert loc to an array so that node.children.include?(loc) can
  # find the right node.
  loc = loc.is_a?(Array) ? loc : loc.loc

  each do |node|
    children_arr = node.children.map(&:loc)
    if children_arr.include?(loc)
      node.remove_child(loc)
      return loc
    end
  end

  # Return nothing if the node was not found.
  nil
end