Class: TuringMachine::Tape

Inherits:
Object
  • Object
show all
Defined in:
lib/turing_machine/tape.rb

Overview

Public: The tape of a Turing machine, combined with the head.

Constant Summary collapse

BLANK_SYMBOL = 
'0'

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(data = BLANK_SYMBOL) ⇒ Tape

Returns a new instance of Tape.



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# File 'lib/turing_machine/tape.rb', line 8

def initialize(data = BLANK_SYMBOL)
  @symbols = data.scan(/./)
  @index = 0
end

Instance Attribute Details

#index ⇒ Object (readonly)

Returns the value of attribute index.



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# File 'lib/turing_machine/tape.rb', line 13

def index
  @index
end

Instance Method Details

#head ⇒ Object 



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# File 'lib/turing_machine/tape.rb', line 15

def head
  @symbols[@index]
end

#head=(symbol) ⇒ Object 



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# File 'lib/turing_machine/tape.rb', line 19

def head=(symbol)
  @symbols[@index] = symbol
end

#shift_left ⇒ Object

Public: Move the head to the left.



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# File 'lib/turing_machine/tape.rb', line 24

def shift_left
  if @index == 0
    @symbols.unshift(BLANK_SYMBOL)
  else
    @index -= 1
  end
end

#shift_right ⇒ Object

Public: Move the head to the right.



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# File 'lib/turing_machine/tape.rb', line 33

def shift_right
  @symbols.push(BLANK_SYMBOL) if @index == @symbols.size - 1
  @index += 1
end

#to_s ⇒ Object 



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# File 'lib/turing_machine/tape.rb', line 38

def to_s
  @symbols.join
end