131 lines
3.0 KiB
Ruby
131 lines
3.0 KiB
Ruby
module Imbecile
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class Regex
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class NFA
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class State
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class Transition
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attr_reader :code_point_range
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attr_reader :destination
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def initialize(code_point_range, destination)
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@code_point_range = code_point_range
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end
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def nil?
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@code_point_range.nil?
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end
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end
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attr_accessor :accepts
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attr_reader :transitions
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def initialize
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@transitions = []
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end
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def add_transition(code_point_range, destination)
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@transitions << Transition.new(code_point_range, destination)
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end
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# Determine the set of states that can be reached by nil transitions.
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# from this state.
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#
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# @return [Set<NFA::State>]
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# Set of states.
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def nil_transition_states
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states = Set[self]
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analyze_state = lambda do |state|
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state.nil_transitions.each do |transition|
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unless states.include?(transition.destination)
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states << transition.destination
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analyze_state[transition.destination]
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end
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end
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end
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analyze_state[self]
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states
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end
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def nil_transitions
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@transitions.select do |transition|
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transition.nil?
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end
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end
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def cp_transitions
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@transitions.reject do |transition|
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transition.nil?
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end
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end
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end
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attr_accessor :start_state
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attr_accessor :end_state
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def initialize
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@start_state = State.new
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@end_state = State.new
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end
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def to_s
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chr = lambda do |value|
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if value < 32 || value > 127
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"{#{value}}"
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else
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value.chr
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end
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end
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rv = ""
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states = {start_state => 0}
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to_visit = [start_state]
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state_id = lambda do |state|
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unless states.include?(state)
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states[state] = states.values.max + 1
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to_visit << state
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end
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states[state]
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end
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visit = lambda do |state|
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accepts_s = state.accepts ? " *" : ""
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rv += "#{state_id[state]}#{accepts_s}:\n"
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state.transitions.each do |transition|
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if transition.nil?
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range_s = "nil"
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else
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range_s = chr[transition.code_point_range.first]
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if transition.code_point_range.size > 1
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range_s += "-" + chr[transition.code_point_range.last]
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end
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end
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accepts_s = dest_state.accepts ? " *" : ""
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rv += " #{range_s} => #{state_id[dest_state]}#{accepts_s}\n"
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end
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end
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while to_visit.size > 0
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visit[to_visit[0]]
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to_visit.slice!(0)
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end
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rv
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end
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class << self
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def empty
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nfa = NFA.new
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nfa.start_state.add_transition(nil, nfa.end_state)
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nfa
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end
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end
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end
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end
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end
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