python - pyparsing:字典列表的语法(erlang)

Question

我正在尝试构建语法来解析 Erlang 标记的元组列表，并将其映射到 pyparsing 中的字典。当我有一个 Dicts 列表时，我遇到了问题。如果 Dict 只有一个元素，语法就可以工作，但是当我添加第二个元素时，现在无法解析它。

当前(简化语法代码(我删除了在这种情况下不需要的语言位):

#!/usr/bin/env python2.7

from pyparsing import *

# Erlang config file definition:
erlangAtom = Word( alphas + '_')
erlangString = dblQuotedString.setParseAction( removeQuotes )

erlangValue = Forward()
erlangList = Forward()

erlangElements = delimitedList( erlangValue )
erlangCSList = Suppress('[') + erlangElements + Suppress(']')
erlangList <<= Group( erlangCSList )
erlangTaggedTuple = Group( Suppress('{') + erlangAtom + Suppress(',') +
                           erlangValue + Suppress('}') )
erlangDict = Dict( Suppress('[') + delimitedList( erlangTaggedTuple ) + 
                   Suppress(']') )

erlangValue <<= ( erlangAtom | erlangString |
                  erlangTaggedTuple |
                  erlangDict | erlangList )

if __name__ == "__main__":
    working = """
[{foo,"bar"}, {baz, "bar2"}]
"""

    broken = """
[
    [{foo,"bar"}, {baz, "bar2"}],
    [{foo,"bob"}, {baz, "fez"}]
]
"""
    w = erlangValue.parseString(working)
    print w.dump()

    b = erlangValue.parseString(broken)
    print "b[0]:", b[0].dump()
    print "b[1]:", b[1].dump()

这给出:

[['foo', 'bar'], ['baz', 'bar2']]
- baz: bar2
- foo: bar

b[0]: [['foo', 'bar'], ['baz', 'bar2'], ['foo', 'bob'], ['baz', 'fez']]
- baz: fez
- foo: bob

b[1]:
Traceback (most recent call last):
  File "./erl_testcase.py", line 39, in <module>
    print "b[1]:", b[1].dump()
  File "/Library/Python/2.7/site-packages/pyparsing.py", line 317, in __getitem__
    return self.__toklist[i]
IndexError: list index out of range

即working 有效，但 broken 不解析为两个列表。

有什么想法吗？

编辑:调整测试用例以更明确地说明预期输出。

Answer 1

好的，所以我以前从未使用过 pyparsing，所以如果我的解决方案没有意义，请原谅。我们开始吧:

据我了解，您需要的是三个主要结构。您犯的最常见错误是对分隔列表进行分组。它们已经分组，所以你有双重分组的问题。这是我的定义:

对于{a,"b"}:

erlangTaggedTuple = Dict(Group(Suppress('{') + erlangAtom + Suppress(',') + erlangValue + Suppress('}') ))

对于 [{a,"b"}, {c,"d"}]:

erlangDict = Suppress('[') + delimitedList( erlangTaggedTuple ) + Suppress(']')

其余的:

erlangList <<= Suppress('[') + delimitedList( Group(erlangDict|erlangList) ) + Suppress(']')

所以我对你的代码的修复是:

#!/usr/bin/env python2.7

from pyparsing import *

# Erlang config file definition:
erlangAtom = Word( alphas + '_')
erlangString = dblQuotedString.setParseAction( removeQuotes )

erlangValue = Forward()
erlangList = Forward()

erlangTaggedTuple = Dict(Group(Suppress('{') + erlangAtom + Suppress(',') +
                           erlangValue + Suppress('}') ))
erlangDict = Suppress('[') + delimitedList( erlangTaggedTuple ) + Suppress(']') 
erlangList <<= Suppress('[') + delimitedList( Group(erlangDict|erlangList) ) + Suppress(']')

erlangValue <<= ( erlangAtom | erlangString |
                  erlangTaggedTuple |
                  erlangDict| erlangList )

if __name__ == "__main__":
    working = """
[{foo,"bar"}, {baz, "bar2"}]
"""

    broken = """
[
    [{foo,"bar"}, {baz, "bar2"}],
    [{foo,"bob"}, {baz, "fez"}]
]
"""
    w = erlangValue.parseString(working)
    print w.dump()

    b = erlangValue.parseString(broken)
    print "b[0]:", b[0].dump()
    print "b[1]:", b[1].dump()

给出输出:

[['foo', 'bar'], ['baz', 'bar2']]
- baz: bar2
- foo: bar
b[0]: [['foo', 'bar'], ['baz', 'bar2']]
- baz: bar2
- foo: bar
b[1]: [['foo', 'bob'], ['baz', 'fez']]
- baz: fez
- foo: bob

希望对您有所帮助，干杯!