Merge branch 'hamlit-test' into 'master'

Replace Haml with Hamlit

What this change does:
- It replaces HAML with [Hamlit](https://github.com/k0kubun/hamlit), a much more efficient implementation of HAML.
- It removes `haml-rails`.
- It adds `hamlit.rb` and removes `haml.rb`.
- It makes things faster and less memory-hungry!

See also #13201.

See merge request !3666

CHANGELOG

 Please view this file on the master branch, on stable branches it's out of date.
 
 v 8.10.0 (unreleased)
+  - Replace Haml with Hamlit to make view rendering faster. !3666
   - Wrap code blocks on Activies and Todos page. !4783 (winniehell)
   - Add Sidekiq queue duration to transaction metrics.
   - Fix MR-auto-close text added to description. !4836

Gemfile

@@ -76,7 +76,7 @@ gem 'rack-cors',    '~> 0.4.0', require: 'rack/cors'
 gem "kaminari", "~> 0.17.0"
 
 # HAML
-gem "haml-rails", '~> 0.9.0'
+gem 'hamlit', '~> 2.5'
 
 # Files attachments
 gem "carrierwave", '~> 0.10.0'

Gemfile.lock

@@ -320,14 +320,10 @@ GEM
     grape-entity (0.4.8)
       activesupport
       multi_json (>= 1.3.2)
-    haml (4.0.7)
+    hamlit (2.5.0)
+      temple (~> 0.7.6)
+      thor
       tilt
-    haml-rails (0.9.0)
-      actionpack (>= 4.0.1)
-      activesupport (>= 4.0.1)
-      haml (>= 4.0.6, < 5.0)
-      html2haml (>= 1.0.1)
-      railties (>= 4.0.1)
     hashie (3.4.3)
     health_check (1.5.1)
       rails (>= 2.3.0)
@@ -337,11 +333,6 @@ GEM
     html-pipeline (1.11.0)
       activesupport (>= 2)
       nokogiri (~> 1.4)
-    html2haml (2.0.0)
-      erubis (~> 2.7.0)
-      haml (~> 4.0.0)
-      nokogiri (~> 1.6.0)
-      ruby_parser (~> 3.5)
     htmlentities (4.3.4)
     http_parser.rb (0.5.3)
     httparty (0.13.7)
@@ -733,6 +724,7 @@ GEM
       railties (>= 3.2.5, < 6)
     teaspoon-jasmine (2.2.0)
       teaspoon (>= 1.0.0)
+    temple (0.7.7)
     term-ansicolor (1.3.2)
       tins (~> 1.0)
     test_after_commit (0.4.2)
@@ -882,7 +874,7 @@ DEPENDENCIES
   gon (~> 6.0.1)
   grape (~> 0.13.0)
   grape-entity (~> 0.4.2)
-  haml-rails (~> 0.9.0)
+  hamlit (~> 2.5)
   health_check (~> 1.5.1)
   hipchat (~> 1.5.0)
   html-pipeline (~> 1.11.0)

app/helpers/application_helper.rb

@@ -197,7 +197,7 @@ module ApplicationHelper
 
   def render_markup(file_name, file_content)
     if gitlab_markdown?(file_name)
-      Haml::Helpers.preserve(markdown(file_content))
+      Hamlit::RailsHelpers.preserve(markdown(file_content))
     elsif asciidoc?(file_name)
       asciidoc(file_content)
     elsif plain?(file_name)

config/initializers/haml.rb

-Haml::Template.options[:ugly] = true
-
-# Remove the `:coffee` and `:coffeescript` filters
-#
-# See https://git.io/vztMu and http://stackoverflow.com/a/17571242/223897
-Haml::Filters.remove_filter('coffee')
-Haml::Filters.remove_filter('coffeescript')

config/initializers/hamlit.rb

+module Hamlit
+  class TemplateHandler
+    def call(template)
+      Engine.new(
+        generator: Temple::Generators::RailsOutputBuffer,
+        attr_quote: '"',
+      ).call(template.source)
+    end
+  end
+end
+
+ActionView::Template.register_template_handler(
+  :haml,
+  Hamlit::TemplateHandler.new,
+)
+
+Hamlit::Filters.remove_filter('coffee')
+Hamlit::Filters.remove_filter('coffeescript')

doc/development/gotchas.md

@@ -46,7 +46,7 @@ Rubocop](https://gitlab.com/gitlab-org/gitlab-ce/blob/8-4-stable/.rubocop.yml#L9
 Using the inline `:coffee` or `:coffeescript` Haml filters comes with a
 performance overhead.
 
-_**Note:** We've [removed these two filters](https://gitlab.com/gitlab-org/gitlab-ce/blob/8-5-stable/config/initializers/haml.rb)
+_**Note:** We've [removed these two filters](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/config/initializers/hamlit.rb)
 in an initializer._
 
 ### Further reading

spec/helpers/visibility_level_helper_spec.rb

 require 'spec_helper'
 
 describe VisibilityLevelHelper do
-  include Haml::Helpers
-
-  before :all do
-    init_haml_helpers
-  end
 
   let(:project)          { build(:project) }
   let(:group)            { build(:group) }