module Nokogiri::CSS::SelectorCache

def [](key)

Retrieve the cached XPath expressions for the key 
def [](key)
  @mutex.synchronize { @cache[key] }
end

def []=(key, value)

Insert the XPath expressions `value` at the cache key 
def []=(key, value)
  @mutex.synchronize { @cache[key] = value }
end

def clear_cache(create_new_object = false)

Clear the cache 
def clear_cache(create_new_object = false)
  @mutex.synchronize do
    if create_new_object # used in tests to avoid 'method redefined' warnings when injecting spies
      @cache = {}
    else
      @cache.clear
    end
  end
end

def key(selector:, visitor:)

Construct a unique key cache key 
def key(selector:, visitor:)
  [selector, visitor.config]
end