Class: DobLinkedList

Inherits:
Object
  • Object
show all
Includes:
Comparable, Enumerable
Defined in:
lib/DobLinkedList.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ DobLinkedList

Returns a new instance of DobLinkedList.



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# File 'lib/DobLinkedList.rb', line 28

def initialize
    @head   = nil
    @tail   = nil
    @length = 0
end

Instance Attribute Details

#head ⇒ Object (readonly)

Returns the value of attribute head.



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# File 'lib/DobLinkedList.rb', line 26

def head
  @head
end

#length ⇒ Object (readonly)

Returns the value of attribute length.



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# File 'lib/DobLinkedList.rb', line 26

def length
  @length
end

#tail ⇒ Object (readonly)

Returns the value of attribute tail.



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# File 'lib/DobLinkedList.rb', line 26

def tail
  @tail
end

Instance Method Details

#<=>(other) ⇒ Object 



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# File 'lib/DobLinkedList.rb', line 137

def <=>(other)
    return nil unless other.instance_of? DobLinkedList
    
    value <=> other.value 
end

#[](index) ⇒ Object 



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# File 'lib/DobLinkedList.rb', line 172

def [](index)
    case index
        when 0, -@length
            @head
        when length-1, -1
            @tail
        else
            find_node(index)
    end
end

#each ⇒ Object 



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# File 'lib/DobLinkedList.rb', line 153

def each
    return nil unless block_given?    
    current = @head
    while current
        yield current
        current = current.next
    end
end

#find_first(&predicate) ⇒ Object 



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# File 'lib/DobLinkedList.rb', line 143

def find_first(&predicate)
    return nil unless block_given?    
    current = @head
    while current
        return current if predicate.call(current)
        current = current.next
    end
end

#find_node(index) ⇒ Object 



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# File 'lib/DobLinkedList.rb', line 162

def find_node (index)
    current = @head
    count = 0
    while current
        return current if count==index
        count += 1
        current = current.next
    end
end

#insertHead(value) ⇒ Object 



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# File 'lib/DobLinkedList.rb', line 47

def insertHead(value)
    node = Node.new(value, nil, nil)
    
    if @head
        node.next = @head
        @head.prev = node
        @head = node
    else
        @head = node
    end
    @length += 1
end

#insertMany(valuesArray) ⇒ Object 



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# File 'lib/DobLinkedList.rb', line 75

def insertMany(valuesArray)

    valuesArray.each {| value |   
  
    node = Node.new(value, nil, nil)
    
    unless @head
        @head = node
    else
        node.prev = @tail
        @tail.next = node
    end
    @tail = node
    @length += 1
    
    }
end

#insertTail(value) ⇒ Object 



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# File 'lib/DobLinkedList.rb', line 61

def insertTail(value)
    node = Node.new(value, nil, nil)
    
    unless @head
        @head = node
    else
        node.prev = @tail
        @tail.next = node
    end
    @tail = node
    @length += 1
end

#remove(node) ⇒ Object 



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# File 'lib/DobLinkedList.rb', line 119

def remove(node)
    return nil unless node    
    
    if node == @head
        if @head.next.nil?
            @head = @tail = nil
        else
            @head = @head.next
        end
    else
        pr = node.prev
        ne = node.next
        pr&.next = ne
        ne&.prev = pr
    end
    @length -= 1
end

#remove_head ⇒ Object 



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# File 'lib/DobLinkedList.rb', line 93

def remove_head

    if @head.next.nil?
        @head = @tail = nil
    else
        @head = @head.next
        @head.prev = nil
    end

    @length -= 1
end

#remove_tail ⇒ Object 



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# File 'lib/DobLinkedList.rb', line 105

def remove_tail

    if @tail.prev.nil?
        @tail = @head = nil

    else

        @tail = @tail.prev
        @tail.next = nil
    end

    @length -= 1
end

#to_s ⇒ Object 



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# File 'lib/DobLinkedList.rb', line 34

def to_s
    listString = ""
    current = @head
    while current

        listString = listString + current.to_s 
        current = current.next
    end

    return listString
end