module Sprockets::Configuration

def digest_class=(klass)
  @digest_class = klass
end

def initialize_configuration(parent)
  @logger                = parent.logger
  @version               = parent.version
  @digest_class          = parent.digest_class
  @context_class         = Class.new(parent.context_class)
  @root                  = parent.root
  @paths                 = parent.paths
  @mime_types            = parent.mime_types
  @mime_exts             = parent.mime_exts
  @encodings             = parent.encodings
  @engines               = parent.engines
  @engine_mime_types     = parent.engine_mime_types
  @transformers          = parent.transformers
  @inverted_transformers = parent.inverted_transformers
  @preprocessors         = parent.preprocessors
  @postprocessors        = parent.postprocessors
  @bundle_reducers       = parent.bundle_reducers
  @bundle_processors     = parent.bundle_processors
  @compressors           = parent.compressors
end

def mutate_config(sym)
  obj = yield self.instance_variable_get("@#{sym}").dup
  self.instance_variable_set("@#{sym}", obj.freeze)
end

def mutate_hash_config(sym, key)
  mutate_config(sym) do |hash|
    obj = yield hash[key].dup
    hash[key] = obj.freeze
    hash
  end
end

def version=(version)
  mutate_config(:version) { version.dup }
end