class ActionView::Digestor

def digest(name:, finder:, dependencies: [])
  dependencies ||= []
  cache_key = [ name, finder.rendered_format, dependencies ].flatten.compact.join(".")
  # this is a correctly done double-checked locking idiom
  # (Concurrent::Map's lookups have volatile semantics)
  finder.digest_cache[cache_key] || @@digest_mutex.synchronize do
    finder.digest_cache.fetch(cache_key) do # re-check under lock
      partial = name.include?("/_")
      root = tree(name, finder, partial)
      dependencies.each do |injected_dep|
        root.children << Injected.new(injected_dep, nil, nil)
      end
      finder.digest_cache[cache_key] = root.digest(finder)
    end
  end
end

def find_template(finder, name, prefixes, partial, keys)
  finder.disable_cache do
    format = finder.rendered_format
    result = finder.find_all(name, prefixes, partial, keys, formats: [format]).first if format
    result || finder.find_all(name, prefixes, partial, keys).first
  end
end

def logger
  ActionView::Base.logger || NullLogger
end

def tree(name, finder, partial = false, seen = {})
  logical_name = name.gsub(%r|/_|, "/")
  if template = find_template(finder, logical_name, [], partial, [])
    finder.rendered_format ||= template.formats.first
    if node = seen[template.identifier] # handle cycles in the tree
      node
    else
      node = seen[template.identifier] = Node.create(name, logical_name, template, partial)
      deps = DependencyTracker.find_dependencies(name, template, finder.view_paths)
      deps.uniq { |n| n.gsub(%r|/_|, "/") }.each do |dep_file|
        node.children << tree(dep_file, finder, true, seen)
      end
      node
    end
  else
    unless name.include?("#") # Dynamic template partial names can never be tracked
      logger.error "  Couldn't find template for digesting: #{name}"
    end
    seen[name] ||= Missing.new(name, logical_name, nil)
  end
end