Look for the given file in the directory containing the current file, and then in each of the directories specified in the RDOC_INCLUDE path

Source Code

# File rdoc/markup/simple_markup/preprocess.rb, line 62
def find_include_file(name)
  to_search = [ File.dirname(@input_file_name) ].concat @include_path
  to_search.each do |dir|
    full_name = File.join(dir, name)
    stat = File.stat(full_name) rescue next
    return full_name if stat.readable?
  end
  nil
end