module MethodSource

def self.clear_cache
  @lines_for_file = {}
end

def self.comment_helper(source_location, name=nil)
  raise SourceNotFoundError, "Could not locate source for #{name}!" unless source_location
  file, line = *source_location
  comment_describing(lines_for(file), line)
end

def self.extract_code(source_location)
  source_helper(source_location)
end

def self.lines_for(file_name, name=nil)
  @lines_for_file ||= {}
  @lines_for_file[file_name] ||= File.readlines(file_name)
rescue Errno::ENOENT => e
  raise SourceNotFoundError, "Could not load source for #{name}: #{e.message}"
end

def self.source_helper(source_location, name=nil)
  raise SourceNotFoundError, "Could not locate source for #{name}!" unless source_location
  file, line = *source_location
  expression_at(lines_for(file), line)
rescue SyntaxError => e
  raise SourceNotFoundError, "Could not parse source for #{name}: #{e.message}"
end

def self.valid_expression?(str)
  complete_expression?(str)
rescue SyntaxError
  false
end