如何修复 Python 中看似有效的 s 表达式的解析错误？

Question

我在将（字符串）s 表达式解析为表示 AST 的嵌套 array/lists 时遇到意外错误。 s-expression 来自 (SerAPI https://github.com/ejgallego/coq-serapi)，但我觉得还不错：

sexp = b'(Answer 3(ObjList((CoqGoal((fg_goals(((name 3)(ty(App(Ind(((Mutind(MPfile(DirPath((Id Logic)(Id Init)(Id Coq))))(DirPath())(Id eq))0)(Instance())))((Ind(((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id bool))0)(Instance())))(App(Const((Constant(MPfile(DirPath((Id Nat)(Id Init)(Id Coq))))(DirPath())(Id odd))(Instance())))((App(Construct((((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id nat))0)2)(Instance())))((Construct((((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id nat))0)1)(Instance())))))))(Construct((((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id bool))0)1)(Instance()))))))(hyp()))))(bg_goals())(shelved_goals())(given_up_goals()))))))\n'

当我尝试解析时收到以下错误消息：

train(policy,optimizer,env,gamma,nb_episodes=nb_episodes,ema_alpha=ema_alpha)
  File "main.py", line 88, in train
    state, reward, done, _ = env.step('Example test_oddb1: Nat.odd 1 = true.')
  File "/Users/korkejudith/home_simulation_research/coq-serapi-python/python_api/coq_env.py", line 120, in step
    state = self.state_embedder(state)
  File "/Users/korkejudith/home_simulation_research/coq-serapi-python/python_api/ai_mathematician.py", line 33, in __call__
    psexp = loads(str(sexp))
  File "/Users/korkejudith/miniconda3/envs/rltp/lib/python3.6/site-packages/sexpdata.py", line 243, in loads
    obj = parse(string, **kwds)
  File "/Users/korkejudith/miniconda3/envs/rltp/lib/python3.6/site-packages/sexpdata.py", line 675, in parse
    return Parser(string, **kwds).parse()
  File "/Users/korkejudith/miniconda3/envs/rltp/lib/python3.6/site-packages/sexpdata.py", line 655, in parse
    (i, sexp) = self.parse_sexp(0)
  File "/Users/korkejudith/miniconda3/envs/rltp/lib/python3.6/site-packages/sexpdata.py", line 641, in parse_sexp
    (i, subsexp) = self.parse_sexp(i + 1)
  File "/Users/korkejudith/miniconda3/envs/rltp/lib/python3.6/site-packages/sexpdata.py", line 642, in parse_sexp
    append(Quoted(subsexp[0]))
IndexError: list index out of range

我尝试了不同版本的字符串，但 none 似乎有效。有人知道可能出了什么问题吗？

重现对我来说失败的不同版本错误的代码：

from sexpdata import loads, dumps

def buffer_test():
    print('buffer_test')
    sexp = ''' b'(Answer 3(ObjList((CoqGoal((fg_goals(((name 3)(ty(Prod(Name(Id n))(Ind(((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id nat))0)(Instance())))(App(Ind(((Mutind(MPfile(DirPath((Id Logic)(Id Init)(Id Coq))))(DirPath())(Id eq))0)(Instance())))((Ind(((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id nat))0)(Instance())))(App(Const((Constant(MPfile(DirPath((Id Nat)(Id Init)(Id Coq))))(DirPath())(Id add))(Instance())))((Construct((((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id nat))0)1)(Instance())))(Rel 1)))(Rel 1)))))(hyp()))))(bg_goals())(shelved_goals())(given_up_goals()))))))\n'
    '''
    print(f'sexp = {sexp}')
    psexp = loads(sexp)

def buffer_str_test():
    print('buffer_str_test')
    sexp = str(''' b'(Answer 3(ObjList((CoqGoal((fg_goals(((name 3)(ty(Prod(Name(Id n))(Ind(((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id nat))0)(Instance())))(App(Ind(((Mutind(MPfile(DirPath((Id Logic)(Id Init)(Id Coq))))(DirPath())(Id eq))0)(Instance())))((Ind(((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id nat))0)(Instance())))(App(Const((Constant(MPfile(DirPath((Id Nat)(Id Init)(Id Coq))))(DirPath())(Id add))(Instance())))((Construct((((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id nat))0)1)(Instance())))(Rel 1)))(Rel 1)))))(hyp()))))(bg_goals())(shelved_goals())(given_up_goals()))))))\n'
    ''')
    print(f'sexp = {sexp}')
    psexp = loads(sexp)

def str_str_test():
    print('str_str_test')
    sexp = str(''' (Answer 3(ObjList((CoqGoal((fg_goals(((name 3)(ty(Prod(Name(Id n))(Ind(((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id nat))0)(Instance())))(App(Ind(((Mutind(MPfile(DirPath((Id Logic)(Id Init)(Id Coq))))(DirPath())(Id eq))0)(Instance())))((Ind(((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id nat))0)(Instance())))(App(Const((Constant(MPfile(DirPath((Id Nat)(Id Init)(Id Coq))))(DirPath())(Id add))(Instance())))((Construct((((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id nat))0)1)(Instance())))(Rel 1)))(Rel 1)))))(hyp()))))(bg_goals())(shelved_goals())(given_up_goals()))))))\n'
    ''')
    print(f'sexp = {sexp}')
    psexp = loads(sexp)

def str_test():
    print('str_test')
    sexp = ''' (Answer 3(ObjList((CoqGoal((fg_goals(((name 3)(ty(Prod(Name(Id n))(Ind(((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id nat))0)(Instance())))(App(Ind(((Mutind(MPfile(DirPath((Id Logic)(Id Init)(Id Coq))))(DirPath())(Id eq))0)(Instance())))((Ind(((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id nat))0)(Instance())))(App(Const((Constant(MPfile(DirPath((Id Nat)(Id Init)(Id Coq))))(DirPath())(Id add))(Instance())))((Construct((((Mutind(MPfile(DirPath((Id Datatypes)(Id Init)(Id Coq))))(DirPath())(Id nat))0)1)(Instance())))(Rel 1)))(Rel 1)))))(hyp()))))(bg_goals())(shelved_goals())(given_up_goals()))))))'
    '''
    print(f'sexp = {sexp}')
    psexp = loads(sexp)

if __name__ == '__main__':
    print('running main')
    buffer_test()
    buffer_str_test()
    str_str_test()
    str_test()
    print('sucessful main')

我也打开了这个gitissue：

https://github.com/jd-boyd/sexpdata/issues/18

交叉发布：

https://www.reddit.com/r/Python/comments/bg87nx/how_does_one_fix_a_parsing_error_with_what_seems/

https://www.quora.com/unanswered/How-does-one-fix-a-parsing-error-with-what-seems-a-valid-s-expression-in-Python

Answer 1

您需要将sexp修改为普通字符串。

The failing code referenced in your stacktrace

        elif c == "'":
            (i, subsexp) = self.parse_sexp(i + 1)
            append(Quoted(subsexp[0]))
            sexp.extend(subsexp[1:])

表明您的表达式中有一个撇号。（调试会清楚地显示。）它从哪里来？

  File "/Users/korkejudith/home_simulation_research/coq-serapi-python/python_api/ai_mathematician.py", line 33, in __call__
    psexp = loads(str(sexp))

这就是罪魁祸首。

如何修复 Python 中看似有效的 s 表达式的解析错误？

How does one fix a parsing error with what seems a valid s-expression in Python?

python

parsing

s-expression