使用正则表达式匹配两个字符串之间的文本

问题描述：

我想使用正则表达式来匹配两个字符串之间的任意文本：

Part 1. Part 2. Part 3 then more text

在这个例子中，我想搜索“第 1 部分”和“第 3 部分”，然后得到介于两者之间的所有内容：“第 2 部分。”

我正在使用 Python 2x。

解决方案 1：

使用re.search

>>> import re
>>> s = 'Part 1. Part 2. Part 3 then more text'
>>> re.search(r'Part 1.(.*?)Part 3', s).group(1)
' Part 2. '
>>> re.search(r'Part 1(.*?)Part 3', s).group(1)
'. Part 2. '

re.findall或者，如果出现多次，则使用。

解决方案 2：

使用正则表达式：

>>> import re
>>> s = 'Part 1. Part 2. Part 3 then more text'
>>> re.search(r'Part 1(.*?)Part 3', s).group(1)
'. Part 2. '

如果没有正则表达式，这个适用于您的示例：

>>> s = 'Part 1. Part 2. Part 3 then more text'
>>> a, b = s.find('Part 1'), s.find('Part 3')
>>> s[a+6:b]
'. Part 2. '

解决方案 3：

我觉得这些复杂程度不断增加的例子很有趣：

ppt = 'abc HERE abc'
ept = 'abc TERM abc'
re_ppt = ppt.replace('HERE', '(.+)')
print()
print(f'{re_ppt=}')
out = re.search(pattern=re_ppt, string=ept)
print(out)
print(out.groups())

ppt = 'abc HERE abc HERE abc'
ept = 'abc TERM1 abc TERM2 abc'
re_ppt = ppt.replace('HERE', '(.+)')
print()
print(f'{re_ppt=}')
out = re.search(pattern=re_ppt, string=ept)
print(out)
print(out.groups())

print()
ppt = """(fun n : nat =>
 nat_ind (fun n0 : nat => n0 + 0 = n0) ?Goal"""
print(f"{ppt=}")
ept = """(fun n : nat =>
 nat_ind (fun n0 : nat => n0 + 0 = n0) (eq_refl : 0 + 0 = 0)"""
print(f'{ept=}')
pattern_meta_var = r'?(w)+'
_ppt = re.sub(pattern=pattern_meta_var, repl='HERE', string=ppt)
print(f'{ppt=}')
_ppt = re.escape(_ppt)
print(f'{ppt=}')
re_ppt = _ppt.replace('HERE', '(.+)')
print(f'{re_ppt=}')
out = re.search(pattern=re_ppt, string=ept)
print(out)
print(out.groups())

print()

# sometimes the actual proof term missing won't have white spaces surrounding it but the ppt will have surrounding spaces where the hole
# would be. So in goal cames I removed the surrounding whitespaces. Then inserted a regex that accepts a hole with or
# without surrounding white spaces. That way in case the proof term in the hole does have surrounding white spaces then
# the regex hole catcher would match it anyway.
ppt = """
   (fun (n' : nat) (IH : n' + 0 = n') => ?Goal0) n)"""
ept = """
   (fun (n' : nat) (IH : n' + 0 = n') =>
    eq_ind_r (fun n0 : nat => S n0 = S n') eq_refl IH : S n' + 0 = S n') n)"""
print(f"{ppt=}")
print(f'{ept=}')
pattern_meta_var = r's*?(w)+s*'
_ppt = re.sub(pattern=pattern_meta_var, repl='HERE', string=ppt)
print(f'{_ppt=}')
_ppt = re.escape(_ppt)
print(f'{_ppt=}')
re_ppt = _ppt.replace('HERE', 's*(.+)s*')
print(f'{re_ppt=}')
out = re.search(pattern=re_ppt, string=ept)
print(out)
assert out is not None, f'expected two holes matched but go {out=}'
print(out.groups())

print()
ppt = """(fun n : nat =>
 nat_ind (fun n0 : nat => n0 + 0 = n0) ?Goal
   (fun (n' : nat) (IH : n' + 0 = n') => ?Goal0) n)"""
print(f"{ppt=}")
ept = """(fun n : nat =>
 nat_ind (fun n0 : nat => n0 + 0 = n0) (eq_refl : 0 + 0 = 0)
   (fun (n' : nat) (IH : n' + 0 = n') =>
    eq_ind_r (fun n0 : nat => S n0 = S n') eq_refl IH : S n' + 0 = S n') n)"""
print(f'{ept=}')
pattern_meta_var = r's*?(w)+s*'
_ppt = re.sub(pattern=pattern_meta_var, repl='HERE', string=ppt)
print(f'{_ppt=}')
_ppt = re.escape(_ppt)
print(f'{_ppt=}')
re_ppt = _ppt.replace('HERE', 's*(.+)s*')
print(f'{re_ppt=}')
out = re.search(pattern=re_ppt, string=ept)
print(out)
print(out.groups())