class Rake::LinkedList

Polylithic linked list structure used to implement several data structures in Rake.

Constants

EMPTY

Attributes

head[R]

tail[R]

Public Class Methods

cons(head, tail) click to toggle source

Cons a new head onto the tail list.

# File lib/rake/linked_list.rb, line 73
def self.cons(head, tail)
  new(head, tail)
end

empty() click to toggle source

The standard empty list class for the given LinkedList class.

# File lib/rake/linked_list.rb, line 78
def self.empty
  self::EMPTY
end

make(*args) click to toggle source

Make a list out of the given arguments. This method is polymorphic

# File lib/rake/linked_list.rb, line 59
def self.make(*args)
  # return an EmptyLinkedList if there are no arguments
  return empty if !args || args.empty?

  # build a LinkedList by starting at the tail and iterating
  # through each argument
  # inject takes an EmptyLinkedList to start
  args.reverse.inject(empty) do |list, item|
    list = cons(item, list)
    list # return the newly created list for each item in the block
  end
end

new(head, tail=EMPTY) click to toggle source

# File lib/rake/linked_list.rb, line 84
def initialize(head, tail=EMPTY)
  @head = head
  @tail = tail
end

Public Instance Methods

==(other) click to toggle source

Lists are structurally equivalent.

# File lib/rake/linked_list.rb, line 25
def ==(other)
  current = self
  while !current.empty? && !other.empty?
    return false if current.head != other.head
    current = current.tail
    other = other.tail
  end
  current.empty? && other.empty?
end

conj(item) click to toggle source

Polymorphically add a new element to the head of a list. The type of head node will be the same list type as the tail.

# File lib/rake/linked_list.rb, line 12
def conj(item)
  self.class.cons(item, self)
end

each() { |head| ... } click to toggle source

For each item in the list.

# File lib/rake/linked_list.rb, line 48
def each
  current = self
  while !current.empty?
    yield(current.head)
    current = current.tail
  end
  self
end

empty?() click to toggle source

Is the list empty? .make guards against a list being empty making any instantiated LinkedList object not empty by default You should consider overriding this method if you implement your own .make method

# File lib/rake/linked_list.rb, line 20
def empty?
  false
end

inspect() click to toggle source

Same as to_s, but with inspected items.

# File lib/rake/linked_list.rb, line 42
def inspect
  items = map(&:inspect).join(", ")
  "LL(#{items})"
end

to_s() click to toggle source

Convert to string: LL(item, item…)

# File lib/rake/linked_list.rb, line 36
def to_s
  items = map(&:to_s).join(", ")
  "LL(#{items})"
end