用于管理字符串文字等项目的转义字符的正则表达式 [英] Regex for managing escaped characters for items like string literals

问题描述

我希望能够将字符串文字与转义引号选项进行匹配.例如，我希望能够搜索这是一个'带有转义\'值的测试' ok"并让它正确地将反斜杠识别为转义字符.我尝试过如下解决方案:

I would like to be able to match a string literal with the option of escaped quotations. For instance, I'd like to be able to search "this is a 'test with escaped\' values' ok" and have it properly recognize the backslash as an escape character. I've tried solutions like the following:

import re
regexc = re.compile(r"\'(.*?)(?<!\\)\'")
match = regexc.search(r""" Example: 'Foo \' Bar'  End. """)
print match.groups() 
# I want ("Foo \' Bar") to be printed above

看了这个，有一个简单的问题，就是使用的转义字符\"本身无法转义.我不知道该怎么做.我想要一个像下面这样的解决方案，但否定的后视断言需要固定长度:

After looking at this, there is a simple problem that the escape character being used, "\", can't be escaped itself. I can't figure out how to do that. I wanted a solution like the following, but negative lookbehind assertions need to be fixed length:

# ...
re.compile(r"\'(.*?)(?<!\\(\\\\)*)\'")
# ...

任何正则表达式大师能够解决这个问题?谢谢.

Any regex gurus able to tackle this problem? Thanks.

推荐答案

我认为这会奏效:

import re
regexc = re.compile(r"(?:^|[^\\])'(([^\\']|\\'|\\\\)*)'")

def check(test, base, target):
    match = regexc.search(base)
    assert match is not None, test+": regex didn't match for "+base
    assert match.group(1) == target, test+": "+target+" not found in "+base
    print "test %s passed"%test

check("Empty","''","")
check("single escape1", r""" Example: 'Foo \' Bar'  End. """,r"Foo \' Bar")
check("single escape2", r"""'\''""",r"\'")
check("double escape",r""" Example2: 'Foo \\' End. """,r"Foo \\")
check("First quote escaped",r"not matched\''a'","a")
check("First quote escaped beginning",r"\''a'","a")

正则表达式 r"(?:^|[^\\])'(([^\\']|\\'|\\\\)*)'" 是仅前向匹配字符串中我们想要的内容:

The regular expression r"(?:^|[^\\])'(([^\\']|\\'|\\\\)*)'" is forward matching only the things that we want inside the string:

1. 不是反斜杠或引号的字符.
2. 转义引用
3. 转义反斜杠

在前面添加额外的正则表达式以检查第一个转义的引号.

Add extra regex at front to check for first quote escaped.

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