Do not include mid-rule actions when tracing rules

This PR, midrule actions should not be included when tracing rules.

Before:
```
❯ exe/lrama --trace=rules ./spec/fixtures/common/basic.y
Grammar rules:
$accept -> program EOI
program -> class
program -> '+' strings_1
program -> '-' strings_2
class -> keyword_class tSTRING keyword_end
$@1 -> ε
$@2 -> ε
class -> keyword_class $@1 tSTRING '!' keyword_end $@2
$@3 -> ε
$@4 -> ε
class -> keyword_class $@3 tSTRING '?' keyword_end $@4
strings_1 -> string_1
strings_2 -> string_1
strings_2 -> string_2
string_1 -> string
string_2 -> string '+'
string -> tSTRING
unused -> tNUMBER
```

After:
```
❯ exe/lrama --trace=rules ./spec/fixtures/common/basic.y
Grammar rules:
$accept -> program EOI
program -> class
program -> '+' strings_1
program -> '-' strings_2
class -> keyword_class tSTRING keyword_end
class -> keyword_class tSTRING '!' keyword_end
class -> keyword_class tSTRING '?' keyword_end
strings_1 -> string_1
strings_2 -> string_1
strings_2 -> string_2
string_1 -> string
string_2 -> string '+'
string -> tSTRING
unused -> tNUMBER
```

lib/lrama/grammar/rule.rb

@@ -21,6 +21,14 @@ def ==(other)
       def display_name
         l = lhs.id.s_value
         r = empty_rule? ? "ε" : rhs.map {|r| r.id.s_value }.join(" ")
+        "#{l} -> #{r}"
+      end
+
+      def display_name_without_action
+        l = lhs.id.s_value
+        r = empty_rule? ? "ε" : rhs.map do |r|
+          r.id.s_value if r.first_set.any?
+        end.compact.join(" ")
 
         "#{l} -> #{r}"
       end

lib/lrama/trace_reporter.rb

@@ -19,7 +19,9 @@ def _report(rules: false, actions: false, **_)
 
     def report_rules
       puts "Grammar rules:"
-      @grammar.rules.each { |rule| puts rule.display_name }
+      @grammar.rules.each do |rule|
+        puts rule.display_name_without_action if rule.lhs.first_set.any?
+      end
     end
 
     def report_actions

spec/lrama/trace_reporter_spec.rb

@@ -0,0 +1,74 @@
+# frozen_string_literal: true
+
+RSpec.describe Lrama::TraceReporter do
+  describe "#report" do
+    let(:path) { "common/basic.y" }
+    let(:y) { File.read(fixture_path(path)) }
+    let(:grammar) do
+      grammar = Lrama::Parser.new(y, path).parse
+      grammar.prepare
+      grammar.validate!
+      grammar
+    end
+
+    context "when rules: true" do
+      it "prints the rules" do
+        expect do
+          described_class.new(grammar).report(rules: true)
+        end.to output(<<~RULES).to_stdout
+          Grammar rules:
+          $accept -> program EOI
+          program -> class
+          program -> '+' strings_1
+          program -> '-' strings_2
+          class -> keyword_class tSTRING keyword_end
+          class -> keyword_class tSTRING '!' keyword_end
+          class -> keyword_class tSTRING '?' keyword_end
+          strings_1 -> string_1
+          strings_2 -> string_1
+          strings_2 -> string_2
+          string_1 -> string
+          string_2 -> string '+'
+          string -> tSTRING
+          unused -> tNUMBER
+        RULES
+      end
+    end
+
+    context "when actions: true" do
+      it "prints the actions" do
+        expect do
+          described_class.new(grammar).report(actions: true)
+        end.to output(<<~RULES).to_stdout
+          Grammar rules with actions:
+          $accept -> program EOI {}
+          program -> class {}
+          program -> '+' strings_1 {}
+          program -> '-' strings_2 {}
+          class -> keyword_class tSTRING keyword_end { code 1 }
+          $@1 -> ε { code 2 }
+          $@2 -> ε { code 3 }
+          class -> keyword_class $@1 tSTRING '!' keyword_end $@2 {}
+          $@3 -> ε { code 4 }
+          $@4 -> ε { code 5 }
+          class -> keyword_class $@3 tSTRING '?' keyword_end $@4 {}
+          strings_1 -> string_1 {}
+          strings_2 -> string_1 {}
+          strings_2 -> string_2 {}
+          string_1 -> string {}
+          string_2 -> string '+' {}
+          string -> tSTRING {}
+          unused -> tNUMBER {}
+        RULES
+      end
+    end
+
+    context 'when empty options' do
+      it 'does not print anything' do
+        expect do
+          described_class.new(grammar).report
+        end.to_not output.to_stdout
+      end
+    end
+  end
+end