带括号的数学运算的正则表达式 [英] Regular expression for math operations with parentheses

问题描述

在java中，我正在尝试编写一个与数学表达式中的单位匹配的正则表达式，即运算符之间的东西

In java, I'm trying to write a regular expression that will match a unit within a mathematical expression, i.e. things that are between operators

我的意思是，在1 + [1 + 2]这样的表达式中，正则表达式应匹配前1，然后是[1 + 2]。

What I mean is, in an expression like 1 + [1 + 2], the regex should match the first 1 and then the [1 + 2].

我所拥有的是* [ （[ - +]？\d +（\.\ + +）？）（\ [。+ \]）] *

What I have is *[([-+]?\d+(\.\d+)?)(\[.+\])] *

其中（[ - +]？\d +（\.\d +）？）应该匹配任何数字和

Of which ([-+]?\d+(\.\d+)?) is supposed to match any number and

（\ [。+ \]）

应该匹配括号内的内容，但是它不起作用......它出于某种原因匹配']'和''之类的东西。

Is supposed to match something inside parentheses, but it isn't working...it's matching things like ']' and ' ' for some reason.

任何帮助都会很棒：）

不幸的是，这是练习的一部分，所以我只能使用基本的java库。 ..它也意味着要用正则表达式练习。我在这里遗漏了一些基本的东西吗？

Unfortunately this is part of an exercise and so I can only use the basic java library...It's also meant to be an exercise in regular expressions. Am I missing something basic here?

推荐答案

您找不到带正则表达式的匹配括号。这是为常规语言提供引理（regexx的数学对象）的结果代表）不持有匹配的开/关parens的语言。

You can't find matching parentheses with regular expressions. This is a consequence of the pumping lemma for regular languages (the mathematical objects that regexes represent) not holding for languages with matched open/close parens.

至少你需要一个无上下文的解析器。这些可以使用ANTLR或JavaCC构建。

You'll need a context-free parser at the least. Those can be built with ANTLR or JavaCC.

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