Class: RubyStructures::LinkedList

Inherits:
Object
  • Object
show all
Defined in:
lib/rubystructures/linked_list.rb

Instance Method Summary collapse

Constructor Details

#initialize ⇒ LinkedList

Public: Create a new instance of LinkedList

Examples

@linked_list = RubyStructures::LinkedList.new # => LinkedList

Returns a new instance of LinkedList.



11
12
13
 
# File 'lib/rubystructures/linked_list.rb', line 11

def initialize
	@head = RubyStructures::Node.new(self, nil)
end

Instance Method Details

#append(value) ⇒ Object

Public: Add a value to the end of the LinkedList

value - Ruby object to be inserted into the LinkedList

Examples

@linked_list.append(42) # => Node

Returns the Node added to the LinkedList.



66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
 
# File 'lib/rubystructures/linked_list.rb', line 66

def append(value)
	if self.empty?
		self.prepend(value)
		return
	end

	element = self.head
	# loop through each element in the LinkedList, until element.next 
	# equals @head, signifying we have reached the end of the list.
	while(element != self.head)
		element = element.next
	end

	new_element = RubyStructures::Node.new(self, value)
	# insert the new element at the end of the LinkedList.
	new_element.next = element.next
	element.next = new_element
end

#empty? ⇒ Boolean

Public: Checks to see if the LinkedList is empty.

Examples

@linked_list.empty? # => false

Returns true if the LinkedList is empty, returns false otherwise.

Returns:

  • (Boolean) 


36
37
38
 
# File 'lib/rubystructures/linked_list.rb', line 36

def empty?
	@head.next == nil
end

#head ⇒ Object

Public: Returns the value at the head of the LinkedList.

Examples

@linked_list.head # => 42

Returns the value held by the Node at the head of the list, otherwise if the list is empty, returns nil.



24
25
26
 
# File 'lib/rubystructures/linked_list.rb', line 24

def head
	@head.next
end

#item_at(index) ⇒ Object

Public: Returns the Node at the desired :index.

index - the Integer index value of Node to return.

Examples

@linked_list.item_at(42) # => #<Node: >

Returns a Node located at position :index in the LinkedList.



131
132
133
134
135
136
137
138
139
140
 
# File 'lib/rubystructures/linked_list.rb', line 131

def item_at(index)
	element = self.head
	count = 0
	while count < index
		return nil if element.nil?
		element = element.next
		count += 1
	end
	element
end

#item_at_head ⇒ Object

Public: Gets the Node at the head of the LinkedList.

Examples

@linked_list.item_at_head # => #<Node: >

Returns the Node at the head of the LinkedList.



117
118
119
 
# File 'lib/rubystructures/linked_list.rb', line 117

def item_at_head
	@head.next
end

#prepend(value) ⇒ Object

Public: Add a value to the beginning of the LinkedList

value - Ruby object to be inserted into the LinkedList

Examples

@linked_list.prepend(42) # => Node

Returns the Node added to the LinkedList.



50
51
52
53
54
 
# File 'lib/rubystructures/linked_list.rb', line 50

def prepend(value)
	element = RubyStructures::Node.new(self, value)
	element.next = @head.next
	@head.next = element
end

#remove(value) ⇒ Object

Public: Finds and removes the first occurrence of a Node with the desired value.

value - the Ruby object value to find and remove from the LinkedList

Examples

@linked_list.remove(42) # => #<Node: >

Returns the node that was removed from the LinkedList



153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
 
# File 'lib/rubystructures/linked_list.rb', line 153

def remove(value)
	element = self.head
	previous_element = @head
	while element.value != value
		if element.next.nil?
			return nil
		else
			previous_element = element
			element = element.next
		end
	end

	previous_element.next = element.next
	element
end

#remove_at_head ⇒ Object

Public: Removes the Node at the head of the LinkedList.

Examples

@linked_list.remove_at_head # => #<Node: >

Returns the Node at the head of the list.



177
178
179
180
181
182
 
# File 'lib/rubystructures/linked_list.rb', line 177

def remove_at_head
	return nil if self.empty?
	element = self.head
	@head.next = nil || element.next
	element
end

#remove_at_tail ⇒ Object

Public: Removes the Node at the tail of the LinkedList.

Examples

@linked_list.remove_at_tail # => #<Node: >

Returns



192
193
194
195
196
197
198
199
200
201
202
203
204
 
# File 'lib/rubystructures/linked_list.rb', line 192

def remove_at_tail
	return nil if self.empty?
	element = self.head
	previous_element = @head

	until element.next.nil?
		previous_element = element
		element = element.next
	end

	previous_element.next = nil
	element
end

#search(value) ⇒ Object

Public: Find an element by its value and return it.

value - Ruby object to be inserted into the LinkedList

Examples

@linked_list.search(42) # => 42

Returns the value of the element if it is in the LinkedList, returns nil otherwise.



96
97
98
99
100
101
102
103
104
105
106
107
 
# File 'lib/rubystructures/linked_list.rb', line 96

def search(value)
	return nil if self.empty?
	element = self.head
	while element.value != value
		if element.next.nil?
			return nil
		else
			element = element.next
		end
	end
	element
end