Rails(Action View) ERB template syntax checker

rails_erb_syntax_check.rb

require 'action_view'
require 'tmpdir'
require 'fileutils'
require 'optparse'

def check_syntax(path, options = {})
  erb = content(path)
  code = ruby_code(erb)
  eval("BEGIN { puts('ok'); return true }; #{code}", nil, path, 0)

rescue SyntaxError
  puts "#{path}: syntax error"
  puts $!  if options[:verbose]
  git_diff(path, options) if options[:show_diff]
end

def git_diff(path, options = {})
  code = ruby_code(content(path), true)

  gcode = ruby_code(git_content(path), true)
  gpath = path + '~'

  diff_cmd = ['diff', *options[:diff_opts].uniq.flatten]
  Dir.mktmpdir do |td|
    dir, file = File.split(path)
    Dir.chdir(td) do
      FileUtils.mkdir_p(dir)
      open(path, 'w') {|o| o.print code }
      open(gpath, 'w') {|o| o.print gcode }
      system(*(diff_cmd << gpath << path))
    end
  end
end

def show_code(path, options = {})
  code = ruby_code(content(path), true)
  print code
end

def content(path)
  open(path, 'r') {|i| i.read }
end

def git_content(path)
  `git show HEAD:#{path}`
end

def ruby_code(erb_text, notext = false)
  erb = ActionView::Template::Handlers::Erubis.new
  erb.extend(Erubis::NoTextEnhancer) if notext
  erb.convert!(erb_text)
  erb.src
end

options = {mode: :check, diff_opts: %w(-u)}
OptionParser.new do |o|
  o.banner = "usage: #{$0} [options] path [path ...]"
  o.separator ''

  o.on('-c', 'syntax check') { options[:mode] = :check }
  o.on('-s', 'show code') { options[:mode] = :code }
  o.on('-d', 'show code diff') { options[:mode] = :diff }
  o.on('-v', 'verbose') { options[:verbose] = true }

  o.separator ''
  o.on('-U NUM', Integer, 'number of context lines') do |num|
    options[:show_diff] = true
    options[:diff_opts] << ['-U', num.to_s]
  end
  o.on('-b', 'ignore changes in the amount of white spaces') do
    options[:diff_opts] << ['-b']
  end
  o.on('-w', 'ignore all spaces') do
    options[:diff_opts] << ['-w']
  end

  o.separator ''
  o.on_tail('-h', 'print usage') do
    puts o
    exit
  end
end.parse!

if ARGV.empty?
  abort 'no files specified'
end

ARGV.each do |path|
  case options[:mode]
  when :check
    check_syntax(path, options)
  when :code
    show_code(path, options)
  when :diff
    git_diff(path, options)
  end
end