class RBS::Environment::UseMap

def build_map(clause)
  case clause
  when AST::Directives::Use::SingleClause
    if clause.new_name
      @map[clause.new_name] = clause.type_name.absolute!
    else
      @map[clause.type_name.name] = clause.type_name.absolute!
    end
  when AST::Directives::Use::WildcardClause
    @table.children.fetch(clause.namespace.absolute!).each do |child|
      @map[child.name] = child
    end
  end
  self
end

def initialize(table:)
  @use_dirs = []
  @map = {}
  @table = table
end

def resolve(type_name)
  resolve?(type_name) || type_name
end

def resolve?(type_name)
  return if type_name.absolute?
  hd, *tl = type_name.namespace.path
  if hd
    # namespace is not empty
    if tn = @map[hd]
      path = [*tn.namespace.path, tn.name, *tl]
      TypeName.new(
        namespace: Namespace.new(absolute: true, path: path),
        name: type_name.name
      )
    end
  else
    @map[type_name.name]
  end
end