Add support for custom XDR generators

lib/xdrgen/compilation.rb

@@ -2,11 +2,12 @@ module Xdrgen
   class Compilation
     extend Memoist
 
-    def initialize(source_paths, output_dir:".", language: :ruby, namespace: nil, options: {})
+    def initialize(source_paths, output_dir:".", language: :ruby, generator: nil, namespace: nil, options: {})
       @source_paths = source_paths
       @output_dir  = output_dir
       @namespace   = namespace
       @language    = language
+      @generator   = generator
       @options     = options
     end
 
@@ -22,8 +23,8 @@ def initialize(source_paths, output_dir:".", language: :ruby, namespace: nil, op
     def compile
       output = Output.new(@source_paths, @output_dir)
 
-
-      generator = Generators.for_language(@language).new(ast, output, @namespace, @options)
+      generator_class = @generator || Generators.for_language(@language)
+      generator = generator_class.new(ast, output, @namespace, @options)
       generator.generate
     ensure
       output.close

spec/lib/xdrgen/custom_generator_spec.rb

@@ -0,0 +1,24 @@
+require 'spec_helper'
+
+describe Xdrgen::Generators do
+  it "can accept a custom generator to generate" do
+    expect(TestGenerator).to receive(:new).with(
+      an_instance_of(Xdrgen::AST::Top),
+      an_instance_of(Xdrgen::Output),
+      "namespace",
+      { option: true },
+    ).and_call_original
+    expect_any_instance_of(TestGenerator).to receive(:generate).with(no_args)
+    Xdrgen::Compilation.new(
+      generator_fixture_paths,
+      output_dir: "output_dir/",
+      generator: TestGenerator,
+      namespace: "namespace",
+      options: { option: true }
+    ).compile
+  end
+end
+
+class TestGenerator < Xdrgen::Generators::Base
+  def generate; end
+end