Rename to propane

lib/propane/lexer/dfa.rb

@@ -0,0 +1,118 @@
+class Propane
+  class Lexer
+
+    class DFA < FA
+
+      def initialize(tokens)
+        super()
+        start_nfa = Regex::NFA.new
+        tokens.each do |name, token|
+          start_nfa.start_state.add_transition(nil, token.nfa.start_state)
+        end
+        @nfa_state_sets = {}
+        @states = []
+        @to_process = Set.new
+        nil_transition_states = start_nfa.start_state.nil_transition_states
+        register_nfa_state_set(nil_transition_states)
+        while @to_process.size > 0
+          state_set = @to_process.first
+          @to_process.delete(state_set)
+          process_nfa_state_set(state_set)
+        end
+        @start_state = @states[0]
+      end
+
+      def build_tables
+        transition_table = []
+        state_table = []
+        states = enumerate
+        states.each do |state, id|
+          accepts =
+            if state.accepts.nil?
+              TOKEN_NONE
+            elsif state.accepts.name
+              state.accepts.id
+            else
+              TOKEN_DROP
+            end
+          state_table << {
+            transition_table_index: transition_table.size,
+            n_transitions: state.transitions.size,
+            accepts: accepts,
+          }
+          state.transitions.each do |transition|
+            transition_table << {
+              first: transition.code_point_range.first,
+              last: transition.code_point_range.last,
+              destination: states[transition.destination],
+            }
+          end
+        end
+        [transition_table, state_table]
+      end
+
+      private
+
+      def register_nfa_state_set(nfa_state_set)
+        unless @nfa_state_sets.include?(nfa_state_set)
+          state_id = @states.size
+          @nfa_state_sets[nfa_state_set] = state_id
+          @states << State.new
+          @to_process << nfa_state_set
+        end
+      end
+
+      def process_nfa_state_set(nfa_state_set)
+        state_id = @nfa_state_sets[nfa_state_set]
+        state = @states[state_id]
+        if state_id > 0
+          nfa_state_set.each do |nfa_state|
+            if nfa_state.accepts
+              if state.accepts
+                if nfa_state.accepts.id < state.accepts.id
+                  state.accepts = nfa_state.accepts
+                end
+              else
+                state.accepts = nfa_state.accepts
+              end
+            end
+          end
+        end
+        transitions = transitions_for(nfa_state_set)
+        while transitions.size > 0
+          subrange = CodePointRange.first_subrange(transitions.map(&:code_point_range))
+          dest_nfa_states = transitions.reduce(Set.new) do |result, transition|
+            if transition.code_point_range.include?(subrange)
+              result << transition.destination
+            end
+            result
+          end
+          dest_nfa_states = dest_nfa_states.reduce(Set.new) do |result, dest_nfa_state|
+            result + dest_nfa_state.nil_transition_states
+          end
+          register_nfa_state_set(dest_nfa_states)
+          dest_state = @states[@nfa_state_sets[dest_nfa_states]]
+          state.add_transition(subrange, dest_state)
+          transitions.delete_if do |transition|
+            transition.code_point_range.last <= subrange.last
+          end
+          transitions.map! do |transition|
+            if transition.code_point_range.first <= subrange.last
+              Regex::NFA::State::Transition.new(CodePointRange.new(subrange.last + 1, transition.code_point_range.last), transition.destination)
+            else
+              transition
+            end
+          end
+        end
+      end
+
+      def transitions_for(nfa_state_set)
+        nfa_state_set.reduce([]) do |result, state|
+          result + state.cp_transitions
+        end
+      end
+
+    end
+
+  end
+end