# Allow for safe recursive lookup of values during variable interpolation. # # @api private class Hiera::InterpolationLoop < StandardError; end class Hiera::RecursiveGuard def initialize @seen = [] end def check(value, &block) if @seen.include?(value) raise Hiera::InterpolationLoop, "Detected in [#{@seen.join(', ')}]" end @seen.push(value) ret = yield @seen.pop ret end end