module Sprockets::Caching

def cache_asset(path)

for finding and building the asset if its not in cache.
logical path or fully expanded path. The `&block` is passed
Cache helper method. Takes a `path` argument which maybe a 
def cache_asset(path)
  # If `cache` is not set, return fast
  if cache.nil?
    yield
  # Check cache for `path`
  elsif (asset = asset_from_hash(cache_get_hash(path.to_s, digest.hexdigest))) && asset.fresh?
    asset
   # Otherwise yield block that slowly finds and builds the asset
  elsif asset = yield
    hash = {}
    asset.encode_with(hash)
    # Save the asset to its path
    cache_set_hash(path.to_s, digest.hexdigest, hash)
    # Since path maybe a logical or full pathname, save the
    # asset its its full path too
    if path.to_s != asset.pathname.to_s
      cache_set_hash(asset.pathname.to_s, digest.hexdigest, hash)
    end
    asset
  end
end