深入理解運算原理｜從簡單的機器到無所不能的程式

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第 5 章

# state 4: scan right looking for end of string

TMRule.new(4, 'c', 4, 'c', :right), # skip c

TMRule.new(4, '_', 5, '_', :left), # find blank, go to state 5

# state 5: scan left looking for beginning of string

TMRule.new(5, 'a', 5, 'a', :left), # skip a

TMRule.new(5, 'b', 5, 'b', :left), # skip b

TMRule.new(5, 'c', 5, 'c', :left), # skip c

TMRule.new(5, 'X', 5, 'X', :left), # skip X

TMRule.new(5, '_', 1, '_', :right) # find blank, go to state 1

])

=> #<struct DTMRulebook rules=[…]>

>> tape = Tape.new([], 'a', ['a', 'a', 'b', 'b', 'b', 'c', 'c', 'c'], '_')

=> #<Tape (a)aabbbccc>

>> dtm = DTM.new(TMConfiguration.new(1, tape), [6], ...