Regex to validate logical && || operators in string

Question

I am trying to create a Regex expression to validate logical && || string combonation and its corresponding opening and closing ()

Answer 1

I think the reason you are not able to validate expressions without a wrapping () is the wrapping parentheses in your core nesting logic. If you take out the following parentheses I note below, then the other two non-wrapped expressions validate:

^(?=^[^()]*\((?>[^()]+|\((?)|\)(?<-DEPTH>))*(?(DEPTH)(?!))\)[^()]*$...
           ^^ remove this                            remove this ^^

Then in order to allow expressions that are not just numerical, you need to replace your restrictive \d with a more liberal definition of what you want to validate, say, [0-9a-zA-Z]:

...[(]*\d+[)]*(\s+(&&|\|\|)\s+[(]*\d+[)]*)*$
       ^^ change these expression ^^

So it would become:

...[(]*[0-9a-zA-Z]+[)]*(\s+(&&|\|\|)\s+[(]*[0-9a-zA-Z]+[)]*)*$

Demo: http://ideone.com/jwkcpL