使用regex和括号返回3个组:operand2 1/operator/operand2 2

Question

我试图在JavaScript中使用Regex，它匹配一个字符串并返回3个组: operand1、operator和operand2。例如，剖析指数子句：

const EXPONENT_REGEX = /(\S+)\s*([\^])\s*(\S+)/
const inpStr = '5 ^ 2 + 10 * 2'
inpStr.match(EXPONENT_REGEX) 
// Returns: ['5 ^ 2', '5', '^', '2'] 
// i.e. [Matched Clause, Operand1, Operator, Operand2] 

但是，在尝试类似的方法来处理括号子句时，以及可能的嵌套括号--我一直无法找到正确的转义方括号和括号的排列方式，以便分组以返回这3个值。考虑：

const PARENTHESES_REGEX = /\([^\(\)]*\)/
const inpStr = '5 ^ 2 + 10 * (10 - (4 + (2 + 1))'
inpStr.match(PARENTHESES_REGEX)

目前，这并不返回任何组，而是匹配“(2+1)”。我该如何构造它来返回第一个示例中相同的3个组呢？在这里看起来应该是：

'2 + 1'，'2'，'+'，'1‘

Answer 1

使用

​

const PARENTHESES_REGEX = /\((-?\d*\.?\d+)\s*([-+\/*])\s*(\d*\.?\d+)\)/g
const inpStr = '5 ^ 2 + 10 * (10 - (4 + (2 + 1))'
console.log([...inpStr.matchAll(PARENTHESES_REGEX)])

​

解释

--------------------------------------------------------------------------------
  \(                       '('
--------------------------------------------------------------------------------
  (                        group and capture to \1:
--------------------------------------------------------------------------------
    -?                       '-' (optional (matching the most amount
                             possible))
--------------------------------------------------------------------------------
    \d*                      digits (0-9) (0 or more times (matching
                             the most amount possible))
--------------------------------------------------------------------------------
    \.?                      '.' (optional (matching the most amount
                             possible))
--------------------------------------------------------------------------------
    \d+                      digits (0-9) (1 or more times (matching
                             the most amount possible))
--------------------------------------------------------------------------------
  )                        end of \1
--------------------------------------------------------------------------------
  \s*                      whitespace (\n, \r, \t, \f, and " ") (0 or
                           more times (matching the most amount
                           possible))
--------------------------------------------------------------------------------
  (                        group and capture to \2:
--------------------------------------------------------------------------------
    [-+\/*]                  any character of: '-', '+', '\/', '*'
--------------------------------------------------------------------------------
  )                        end of \2
--------------------------------------------------------------------------------
  \s*                      whitespace (\n, \r, \t, \f, and " ") (0 or
                           more times (matching the most amount
                           possible))
--------------------------------------------------------------------------------
  (                        group and capture to \3:
--------------------------------------------------------------------------------
    \d*                      digits (0-9) (0 or more times (matching
                             the most amount possible))
--------------------------------------------------------------------------------
    \.?                      '.' (optional (matching the most amount
                             possible))
--------------------------------------------------------------------------------
    \d+                      digits (0-9) (1 or more times (matching
                             the most amount possible))
--------------------------------------------------------------------------------
  )                        end of \3
--------------------------------------------------------------------------------
  \)                       ')'

结果：(4) ['(2 + 1)', '2', '+', '1', index: 24, input: '5 ^ 2 + 10 * (10 - (4 + (2 + 1))', groups: undefined]