正则表达式捕获字符串中的嵌套函数

Question

I want to capture all the function names present in an expresison, for example:

DECODE (TRUE, NOT ISNULL (parameter1),VARIABLE1, ISNULL (Parameter2) AND NOT ISNULL (parameter1),Variable3, ISNULL (parameter) AND ISNULL (parameter) AND NOT ISNULL (parameter),VARIABLE2)

I had tried

([a-zA-Z0-9]+\s*\(([\w\s\,]+)?\)\s*)+

The regex is capturing all the function names except DECODE . Could anyone tell what mistake I'm doing?

Answer 1

Please try this one

([a-zA-Z0-9]+\s*)(\(.+?\))

Basically, it capture 2 groups: before the ( and inside (*) . You can choose which group to extract later. You can watch the demo in here: https://regex101.com/r/9ILSYn/1

Or you can just put in the ?: in the later group to mark it as a non-capturing group

([a-zA-Z0-9]+\s*)(?:\(.+?\))

In your before-edit regex, you didn't split the capturing groups so it mixed the first function with the parameters.

In your updated regex, you are capturing the groups with word and white space inside the (*) , which is not including some character like ( , so it didn't capture the DECODE