Support coffee filter via tilt

fast_haml.gemspec

@@ -26,6 +26,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "appraisal"
   spec.add_development_dependency "benchmark-ips"
   spec.add_development_dependency "bundler"
+  spec.add_development_dependency "coffee-script"
   spec.add_development_dependency "coveralls"
   spec.add_development_dependency "haml"
   spec.add_development_dependency "rake"

lib/fast_haml/filter_compilers.rb

@@ -29,6 +29,7 @@ def self.find(name)
 end
 
 require 'fast_haml/filter_compilers/cdata'
+require 'fast_haml/filter_compilers/coffee'
 require 'fast_haml/filter_compilers/css'
 require 'fast_haml/filter_compilers/escaped'
 require 'fast_haml/filter_compilers/javascript'

lib/fast_haml/filter_compilers/coffee.rb

@@ -0,0 +1,14 @@
+require 'fast_haml/filter_compilers/tilt_base'
+
+module FastHaml
+  module FilterCompilers
+    class Coffee < TiltBase
+      def compile(texts)
+        temple = compile_with_tilt('coffee', texts)
+        [:haml, :tag, 'script', false, [:html, :attrs], [:html, :js, temple]]
+      end
+    end
+
+    register(:coffee, Coffee)
+  end
+end

spec/render/filters/coffee_spec.rb

@@ -0,0 +1,25 @@
+require 'spec_helper'
+
+RSpec.describe 'CoffeeScript filter renderiong', type: :render do
+  it 'renders CoffeeScript filter' do
+    html = render_string(<<HAML)
+:coffee
+  square = (x) -> x * x
+  square(3)
+HAML
+    expect(html).to include('<script>')
+    expect(html).to include('square = function(x)')
+    expect(html).to include('square(3)')
+  end
+
+  it 'parses string interpolation' do
+    html = render_string(<<'HAML')
+:coffee
+  square = (x) -> x * x
+  square(#{1 + 2})
+HAML
+    expect(html).to include('<script>')
+    expect(html).to include('square = function(x)')
+    expect(html).to include('square(3)')
+  end
+end