我正在查看Python中的一些解析器组合器库(Parsy更准确地说),我目前面临以下问题,通过下面一个简单的工作示例进行了简化:
text = '''
AAAAAAAAAA AAAAAAAA AAAAAAAAAAAAAA
BBBBBBB START THE TEXT HERE SHOULD
BE CAPTURED STOP CCCCCCCCCC CCCCCC
'''
start, stop = r"STARTS?", r"STOPS?"
s = section(text, start, stop)
print(s)
应输出:
THE TEXT HERE SHOULD
BE CAPTURED
我目前正在研究的解决方案是通过执行一个regex前瞻,它工作得很好,但我最初的问题是将这些小regex组合在一起,这可能会变得很混乱,并且会给其他人带来以后维护的问题
from typing import Pattern, TypeVar
import re
# A Generic type declaration.
T = TypeVar("T")
def first(text: str, pattern: str, default: T, flags=0) -> T:
"""
Given a `text`, a regex `pattern` and a `default` value, return the first match
in `text`. Otherwise return a `default` value if no match is found.
"""
match = re.findall(pattern, text, flags=flags)
return match[0] if len(match) > 0 else default
def section(text: str, begin: str, end: str) -> str:
"""
Given a `text` and two `start` and `stop` regexes, return the captured group
found in the interval. Otherwise, return an empty string if no match is found.
"""
return first(text, fr"{begin}([\s\S]*?)(?={end})", default="")
解析器组合器似乎非常适合此类情况,但我无法重现与工作解决方案相同的行为,欢迎提供任何提示:
# A Simpler example with hardcoded stuff
from parsy import regex, seq, string
text = '''
AAAAAAAAAA AAAAAAAA AAAAAAAAAAAAAA
BBBBBBB START THE TEXT HERE SHOULD
BE CAPTURED STOP CCCCCCCCCC CCCCCC
'''
start = regex(r"STARTS?")
middle = regex(r"[\s\S]*").optional()
stop = regex(r"STOPS?")
eol = string("\n")
# Work fine
start.parse("START")
middle.parse("")
stop.parse("STOP")
section = seq(
start,
middle,
stop
)
# Simpler case, breaks
section.parse("START AAA STOP")
给出:
---------------------------------------------------------------------------
ParseError Traceback (most recent call last)
<ipython-input-260-fdec112e1648> in <module>
24 )
25 # Simpler case, breaks
---> 26 section.parse("START AAA STOP")
~/.venv/lib/python3.8/site-packages/parsy/__init__.py in parse(self, stream)
88 def parse(self, stream):
89 """Parse a string or list of tokens and return the result or raise a ParseError."""
---> 90 (result, _) = (self << eof).parse_partial(stream)
91 return result
92
~/.venv/lib/python3.8/site-packages/parsy/__init__.py in parse_partial(self, stream)
102 return (result.value, stream[result.index:])
103 else:
--> 104 raise ParseError(result.expected, stream, result.furthest)
105
106 def bind(self, bind_fn):
ParseError: expected 'STOPS?' at 0:14
你试过使用split吗
根据我对你们项目要求的理解。我会这样做:
问题是
middle
解析器匹配文本直到结束,因此stop
解析器不需要使用任何内容:印刷品
避免此行为的一个解决方案是对
middle
正则表达式使用lookahead选项:这确保匹配的文本后面跟着“停止”字
或者,您可以使用Parsy的^{} 方法:
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