Move generation logic to new Generator class

assets/parser.d.erb

@@ -1,8 +1,8 @@
-<% if @modulename %>
-module <%= @modulename %>;
+<% if @grammar.modulename %>
+module <%= @grammar.modulename %>;
 
 <% end %>
-class <%= classname %>
+class <%= @classname %>
 {
     enum
     {
@@ -117,7 +117,7 @@ class <%= classname %>
             uint accepts;
         }
 
-<% transition_table, state_table = lexer.build_tables %>
+<% transition_table, state_table = @lexer.build_tables %>
         private static const Transition transitions[] = [
 <% transition_table.each do |transition_table_entry| %>
             Transition(<%= transition_table_entry[:first] %>u, <%= transition_table_entry[:last] %>u, <%= transition_table_entry[:destination] %>u),

lib/propane.rb

@@ -5,6 +5,7 @@ require_relative "propane/code_point_range"
 require_relative "propane/fa"
 require_relative "propane/fa/state"
 require_relative "propane/fa/state/transition"
+require_relative "propane/generator"
 require_relative "propane/grammar"
 require_relative "propane/lexer"
 require_relative "propane/lexer/dfa"
@@ -36,64 +37,13 @@ class Propane
   class Error < RuntimeError
   end
 
-  def initialize(input)
-    @grammar = Grammar.new(input)
-    @classname = @grammar.classname
-    @modulename = @grammar.modulename
-    @rule_sets = @grammar.rule_sets
-  end
-
-  def generate(output_file, log_file)
-    expand_rules
-    lexer = Lexer.new(@grammar.tokens, @grammar.drop_tokens)
-    parser = Parser.new(@rule_sets)
-    classname = @classname || File.basename(output_file).sub(%r{[^a-zA-Z0-9].*}, "").capitalize
-    erb = ERB.new(File.read(File.join(File.dirname(File.expand_path(__FILE__)), "../assets/parser.d.erb")), trim_mode: "<>")
-    result = erb.result(binding.clone)
-    File.open(output_file, "wb") do |fh|
-      fh.write(result)
-    end
-  end
-
-  private
-
-  def expand_rules
-    tokens_by_name = {}
-    @grammar.tokens.each do |token|
-      if tokens_by_name.include?(token.name)
-        raise Error.new("Duplicate token name #{token.name.inspect}")
-      end
-      tokens_by_name[token.name] = token
-    end
-    @rule_sets.each do |rule_name, rule_set|
-      if tokens_by_name.include?(rule_name)
-        raise Error.new("Rule name collides with token name #{rule_name.inspect}")
-      end
-    end
-    unless @rule_sets["Start"]
-      raise Error.new("Start rule not found")
-    end
-    @rule_sets.each do |rule_name, rule_set|
-      rule_set.rules.each do |rule|
-        rule.components.map! do |component|
-          if tokens_by_name[component]
-            tokens_by_name[component]
-          elsif @rule_sets[component]
-            @rule_sets[component]
-          else
-            raise Error.new("Symbol #{component} not found")
-          end
-        end
-      end
-    end
-  end
-
   class << self
 
     def run(input_file, output_file, log_file)
       begin
-        propane = Propane.new(File.read(input_file))
-        propane.generate(output_file, log_file)
+        grammar = Grammar.new(File.read(input_file))
+        generator = Generator.new(grammar, output_file, log_file)
+        generator.generate
       rescue Error => e
         $stderr.puts e.message
         return 2

lib/propane/generator.rb

@@ -0,0 +1,58 @@
+class Propane
+
+  class Generator
+
+    def initialize(grammar, output_file, log_file)
+      @grammar = grammar
+      @output_file = output_file
+      @log_file = log_file
+      @classname = @grammar.classname || File.basename(output_file).sub(%r{[^a-zA-Z0-9].*}, "").capitalize
+      process_grammar!
+      @lexer = Lexer.new(@grammar.tokens, @grammar.drop_tokens)
+      @parser = Parser.new(@grammar.rule_sets)
+    end
+
+    def generate
+      erb = ERB.new(File.read(File.join(File.dirname(File.expand_path(__FILE__)), "../../assets/parser.d.erb")), trim_mode: "<>")
+      result = erb.result(binding.clone)
+      File.open(@output_file, "wb") do |fh|
+        fh.write(result)
+      end
+    end
+
+    private
+
+    def process_grammar!
+      tokens_by_name = {}
+      @grammar.tokens.each do |token|
+        if tokens_by_name.include?(token.name)
+          raise Error.new("Duplicate token name #{token.name.inspect}")
+        end
+        tokens_by_name[token.name] = token
+      end
+      @grammar.rule_sets.each do |rule_name, rule_set|
+        if tokens_by_name.include?(rule_name)
+          raise Error.new("Rule name collides with token name #{rule_name.inspect}")
+        end
+      end
+      unless @grammar.rule_sets["Start"]
+        raise Error.new("Start rule not found")
+      end
+      @grammar.rule_sets.each do |rule_name, rule_set|
+        rule_set.rules.each do |rule|
+          rule.components.map! do |component|
+            if tokens_by_name[component]
+              tokens_by_name[component]
+            elsif @grammar.rule_sets[component]
+              @grammar.rule_sets[component]
+            else
+              raise Error.new("Symbol #{component} not found")
+            end
+          end
+        end
+      end
+    end
+
+  end
+
+end