Question

For example, it should match (aaa), ((aaa)), (((aaa))), but not ((aaa) or (aaa)).
Is it even possible?

P.S.如果是,我需要 Java本的定期表述。

Answer 1

If you re willing to do a little more than regex (and I mean just a little), you can use this function.

check_parens( (((aaa))) );
check_parens( ((aaa))) );
check_parens( aaa );


function check_parens(hay) {
    var re = /((+)(?:[^)]+)()+)/g;
    var matches = re.exec(hay);

    if (matches === null || matches[1].length !== matches[2].length)
        alert("Too bad...");
    else 
        alert("We re good!");
}

demo

Answer 2

您描述的语言是:http://en.wikipedia.org/wiki/Context-free_grammar” rel=“nofollow” ;context free;而不是,因此没有这种定期表述。我们可以轻易显示 homo吗?”

It might be possible with some regex expansions, but not in standard regular expression, which originally standed for regular languages.

demo

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