add RelatonBib#gramma_hash method

lib/relaton_bib.rb

@@ -79,6 +79,13 @@ def parse_yaml(yaml, classes = [])
     end
   end
 
+  def self.grammar_hash
+    gem_path = File.expand_path "..", __dir__
+    grammars_path = File.join gem_path, "grammars", "*"
+    grammars = Dir[grammars_path].sort.map { |gp| File.read gp }.join
+    Digest::MD5.hexdigest grammars
+  end
+
   private
 
   # @param array [Array]

lib/relaton_bib/version.rb

@@ -1,3 +1,3 @@
 module RelatonBib
-  VERSION = "1.14.0".freeze
+  VERSION = "1.14.1".freeze
 end

spec/relaton_bib_spec.rb

@@ -3,6 +3,12 @@
     expect(RelatonBib::VERSION).not_to be nil
   end
 
+  it "returns grammar hash" do
+    hash = RelatonBib.grammar_hash
+    expect(hash).to be_instance_of String
+    expect(hash.size).to eq 32
+  end
+
   context "parse date" do
     it "February 2012" do
       expect(RelatonBib.parse_date("February 2012")).to eq "2012-02"