90 lines
2.8 KiB
Ruby
90 lines
2.8 KiB
Ruby
module Imbecile
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class Lexer
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class DFA < FA
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def initialize(tokens)
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super()
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start_nfa = Regex::NFA.new
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tokens.each do |token|
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start_nfa.start_state.add_transition(nil, token.nfa.start_state)
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end
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@nfa_state_sets = {}
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@states = []
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@to_process = Set.new
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nil_transition_states = start_nfa.start_state.nil_transition_states
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register_nfa_state_set(nil_transition_states)
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while @to_process.size > 0
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state_set = @to_process.first
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@to_process.delete(state_set)
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process_nfa_state_set(state_set)
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end
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@start_state = @states[0]
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end
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private
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def register_nfa_state_set(nfa_state_set)
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unless @nfa_state_sets.include?(nfa_state_set)
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state_id = @states.size
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@nfa_state_sets[nfa_state_set] = state_id
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@states << State.new
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@to_process << nfa_state_set
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end
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end
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def process_nfa_state_set(nfa_state_set)
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state_id = @nfa_state_sets[nfa_state_set]
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state = @states[state_id]
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if state_id > 0
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nfa_state_set.each do |nfa_state|
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if nfa_state.accepts
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if state.accepts
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if nfa_state.accepts.id < state.accepts.id
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state.accepts = nfa_state.accepts
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end
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else
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state.accepts = nfa_state.accepts
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end
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end
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end
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end
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transitions = transitions_for(nfa_state_set)
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while transitions.size > 0
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subrange = CodePointRange.first_subrange(transitions.map(&:code_point_range))
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dest_nfa_states = transitions.reduce(Set.new) do |result, transition|
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if transition.code_point_range.include?(subrange)
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result << transition.destination
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end
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result
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end
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dest_nfa_states = dest_nfa_states.reduce(Set.new) do |result, dest_nfa_state|
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result + dest_nfa_state.nil_transition_states
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end
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register_nfa_state_set(dest_nfa_states)
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dest_state = @states[@nfa_state_sets[dest_nfa_states]]
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state.add_transition(subrange, dest_state)
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transitions.delete_if do |transition|
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transition.code_point_range.last <= subrange.last
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end
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transitions.map! do |transition|
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if transition.code_point_range.first <= subrange.last
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Regex::NFA::State::Transition.new(CodePointRange.new(subrange.last + 1, transition.code_point_range.last), transition.destination)
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else
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transition
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end
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end
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end
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end
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def transitions_for(nfa_state_set)
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nfa_state_set.reduce([]) do |result, state|
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result + state.cp_transitions
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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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