#
# An assortment of example machines to show different ways to
# define states and machines, as well as demonstrate actions and
# special transitions.
#
require 'dfa'
# States set to recognize "(ab|ba)a*"
def regex_machine
return DFA.new [
State.new("A", {'a' => "B", 'b' => "C"}),
State.new("B", {'b' => "D"}),
State.new("C", {'a' => "E"}),
State.new("D", {'a' => "F"}),
State.new("E", {'a' => "F"}),
State.new("F", {'a' => "F"}),
]
end
# States to implement Figure 1 from wikipedia's Finite state machine page
# Represents two doors/switches
def door_machine
return DFA.new [
State.new("Opened", {'close_door' => "Closed"}),
State.new("Closed", {'open_door' => "Opened"})
]
end
# States to implement Figure 2 from wikipedia page
# Recognizes just the word 'nice'. :dot matches any input.
def nice_machine
final = state "5", :final do
transition :dot => :error
on_enter { |x| puts "!! You spelled the word nice correctly" }
end
return DFA.new [
State.new("1", {'n' => "2", :dot => :error}),
State.new("2", {'i' => "3", :dot => :error}),
State.new("3", {'c' => "4", :dot => :error}),
State.new("4", {'e' => "5", :dot => :error}),
final
]
end
# States to implement Figure 3 from wikipedia page
# Determine whether the number of zeros in a string of 1's and 0's
# is odd or even.
def binary_machine
return DFA.new [
State.new("Even", {'1' => "Even", '0' => "Odd"}),
State.new("Odd", {'1' => "Odd", '0' => "Even"})
]
end
# Match Lisp's cdr/car/etc. functions
def carcdr
return automaton 1, {"c" => 2},
2, {"a" => 2, "d" => 2, "r" => 3},
3, {"r" => 3}
end
