Add report_unused_terms private method

lib/lrama/states_reporter.rb

@@ -16,15 +16,53 @@ def report(io, **options)
 
     private
 
-    def _report(io, grammar: false, states: false, itemsets: false, lookaheads: false, solved: false, counterexamples: false, verbose: false)
-      # TODO: Unused terms
+    def _report(io, term: false, grammar: false, states: false, itemsets: false, lookaheads: false, solved: false, counterexamples: false, verbose: false)
       # TODO: Unused rules
 
+      report_unused_terms(io) if term
       report_conflicts(io)
       report_grammar(io) if grammar
       report_states(io, itemsets, lookaheads, solved, counterexamples, verbose)
     end
 
+    def report_unused_terms(io)
+      io << "Unused Terms\n\n"
+
+      results = []
+      terms = []
+      used_symbols = []
+
+      terms = @states.symbols.select(&:term?)
+
+      @states.states.select do |state|
+        state.shifts.map(&:next_sym)
+      end
+
+      @states.states.each do |state|
+        state.reduces.select do |reduce|
+          used_symbols << reduce.look_ahead.flatten if !reduce.look_ahead.nil?
+        end
+      end
+
+      @states.states.each do |state|
+        used_symbols << state.shifts.map(&:next_sym).select(&:term?).flatten
+      end
+
+      used_symbols = used_symbols.flatten
+
+      results = terms.select do |term|
+        !used_symbols.include?(term)
+      end
+
+      results.each_with_index do |term, index|
+        io << sprintf("%5d %s\n", index, term.id.s_value)
+      end
+
+      if !results.empty?
+        io << "\n\n"
+      end
+    end
+
     def report_conflicts(io)
       has_conflict = false
 

spec/lrama/states_spec.rb

@@ -15,9 +15,24 @@
       states.compute
 
       io = StringIO.new
-      states.reporter.report(io, grammar: true, states: true, itemsets: true, lookaheads: true)
+      states.reporter.report(io, term: true, grammar: true, states: true, itemsets: true, lookaheads: true)
 
       expect(io.string).to eq(<<~STR)
+        Unused Terms
+
+            0 YYerror
+            1 YYUNDEF
+            2 '\\\\'
+            3 '\\13'
+            4 keyword_class2
+            5 tNUMBER
+            6 tPLUS
+            7 tMINUS
+            8 tEQ
+            9 tEQEQ
+           10 '>'
+
+
         State 1 conflicts: 2 shift/reduce, 1 reduce/reduce