试试这个 PCRE 正则表达式:
(?<!\\) # negative look-behind to make sure start is not escaped
(?: # start non-capture group for all possible match starts
# group 1, match dollar signs only
# single or double dollar sign enforced by look-arounds
((?<!\$)\${1,2}(?!\$))|
# group 2, match escaped parenthesis
(\\\()|
# group 3, match escaped bracket
(\\\[)|
# group 4, match begin equation
(\\begin\{equation\})
)
# if group 1 was start
(?(1)
# non greedy match everything in between
# group 1 matches do not support recursion
(.*?)(?<!\\)
# match ending double or single dollar signs
(?<!\$)\1(?!\$)|
# else
(?:
# greedily and recursively match everything in between
# groups 2, 3 and 4 support recursion
(.*(?R)?.*)(?<!\\)
(?:
# if group 2 was start, escaped parenthesis is end
(?(2)\\\)|
# if group 3 was start, escaped bracket is end
(?(3)\\\]|
# else group 4 was start, match end equation
\\end\{equation\}
)
))))
请参阅此正则表达式:https ://regex101.com/r/wP2aV6/25
由于此正则表达式使用递归,它将正确处理嵌套的数学表达式。
这仅适用于 PCRE 兼容的正则表达式引擎。它需要正则表达式引擎的一些高级功能,例如负向回溯、条件表达式和递归,这些在所有正则表达式引擎中都不存在。
除非你需要一些非常简单的东西,否则我建议不要使用这个正则表达式,而是使用适当的 LaTeX 解析器。