def t_STRUCTURE(t):
    """([ ]+)field[ ]declaration:[ ](.+);\\n"""
    tab = int(len(t.lexer.lexmatch.group(10)) / 2)
    declaration = t.lexer.lexmatch.group(11).replace('\n', ' ')
    t.value = [tab, {'field': declaration, 'value': None}]
    return t
