Write output file from ERB template

assets/parser.d.erb

@@ -0,0 +1,7 @@
+<% if grammar.modulename %>
+module <%= grammar.modulename %>;
+
+<% end %>
+class <%= classname %>
+{
+}

lib/imbecile.rb

@@ -1,6 +1,7 @@
 require_relative "imbecile/cli"
 require_relative "imbecile/grammar"
 require_relative "imbecile/version"
+require "erb"
 
 module Imbecile
 
@@ -11,6 +12,12 @@ module Imbecile
       unless grammar.load(input_file)
         return 2
       end
+      classname = grammar.classname || grammar.capitalize
+      erb = ERB.new(File.read(File.join(File.dirname(File.expand_path(__FILE__)), "../assets/parser.d.erb")), nil, "<>")
+      result = erb.result(binding.clone)
+      File.open(output_file, "wb") do |fh|
+        fh.write(result)
+      end
       return 0
     end
 

lib/imbecile/grammar.rb

@@ -1,6 +1,12 @@
 module Imbecile
   class Grammar
 
+    # @return [String, nil] Module name.
+    attr_reader :modulename
+
+    # @return [String, nil] Class name.
+    attr_reader :classname
+
     def initialize
       @tokens = {}
       @rules = {}
@@ -16,8 +22,10 @@ module Imbecile
           # Skip comment lines.
         elsif line =~ /^\s*$/
           # Skip blank lines.
+        elsif line =~ /^\s*module\s+(\S+)$/
+          @modulename = $1
         elsif line =~ /^\s*class\s+(\S+)$/
-          @class = $1
+          @classname = $1
         elsif line =~ /^\s*token\s+(\S+)\s+(.*)$/
           name, expr = $1, $2
           unless name =~ /^[a-zA-Z_][a-zA-Z_0-9]*$/