python - 优雅的解析这个？ "a,b,c",d ,"e,f"

Question

我希望将这些类型的字符串解析为 Python 中的列表:

"a,b,c",d,"e,f"        =>  ['a','b','c'] , ['d'] , ['e','f']
"a,b,c",d,e            =>  ['a','b','c'] , ['d'] , ['e']
a,b,"c,d,e,f"          =>  ['a'],['b'],['c','d','e','f']
a,"b,c,d",{x(a,b,c-d)} =>  ['a'],['b','c','d'],[('x',['a'],['b'],['c-d'])]

它嵌套，所以我怀疑正则表达式已经过时了。我所能想到的就是开始计算引号和括号来解析它，但这似乎非常不雅。或者也许首先匹配引号并用 somechar 替换它们之间的逗号，然后按逗号拆分，直到完成所有嵌套，最后在 somechar 上重新拆分。

有什么想法吗？

Answer 1

所以，这就是您的“诚实的 Python 解析器”。为您编码而不是回答问题，但如果您使用它我会很好:-)

QUOTE = '"'
SEP = ',(){}"'
S_BRACKET = '{'
E_BRACKET = '}'
S_PAREN = '('

def parse_plain(string):
    counter = 0
    token = ""
    while counter<len(string):
        if string[counter] in SEP:
            counter += 1
            break
        token += string[counter]
        counter += 1
    return counter, token

def parse_bracket(string):
    counter = 1
    fwd, token = parse_plain(string[counter:])
    output = [token]
    counter += fwd
    fwd, token = parse_(string[counter:])
    output += token
    counter += fwd
    output = [tuple(output)]
    return counter, output

def parse_quote(string):
    counter = 1
    output = []
    while counter<len(string):
        if counter > 1 and string[counter - 1] == QUOTE:
            counter += 1
            break
        fwd, token = parse_plain(string[counter:])
        output.append(token)
        counter += fwd
    return counter, output

def parse_(string):
    output = []
    counter = 0
    while counter < len(string):
        if string[counter].isalpha():
            fwd, token = parse_plain(string[counter:])
            token = [token]
        elif string[counter] == QUOTE:
            fwd, token = parse_quote(string[counter:])
        elif string[counter] == S_BRACKET:
            fwd, token = parse_bracket(string[counter:])
        elif string[counter] == E_BRACKET:
            counter += 1
            break
        else:
            counter += 1
            continue
        output.append(token)
        counter += fwd
    return counter, output

def parse(string):
    return parse_(string)[1]

并测试输出:

>>> print parse('''"a,b,c",d,"e,f"''')
[['a', 'b', 'c'], ['d'], ['e', 'f']]
>>> print parse('''"a,b,c",d,e ''')
[['a', 'b', 'c'], ['d'], ['e ']]
>>> print parse('''a,b,"c,d,e,f"''')
[['a'], ['b'], ['c', 'd', 'e', 'f']]
>>> print parse('''a,"b,c,d",{x(a,b,c-d)}''')
[['a'], ['b', 'c', 'd'], [('x', ['a'], ['b'], ['c-d'])]]
>>> print parse('''{x(a,{y("b,c,d",e)})},z''')
[[('x', ['a'], [('y', ['b', 'c', 'd'], ['e'], ['z'])])]]
>>>