Question

I am currently designing a GUI that allows the user to define some logic. I don’t want it getting too complex, so I am limiting it to a single set of brackets. So, the idea is to check that between the opening and closing brackets there are not any other opening brackets.

eg. IF ( a + b OR **(** b+ c) would alert with error.

So I decided with the route of:

• Find the first open bracket
• Find the first close bracket
• Using those indices search between and find any open brackets
• If any open brackets are found display an error
• Continue the loop for any other logic

Here’s the code. I think its pretty horrific and I am sure there must be a better way to do this. Some kind of IndexOf maybe.

<select rel="OpenBracket" id="open1">
    <option value=""></option>
    <option value="(">(</option>
</select>
Some True/Fale here
<select rel="CloseBracket" id="close1">
    <option value=""></option>
    <option value=")">)</option>
</select>
AND
<br />
<select rel="OpenBracket" id="open2">
    <option value=""></option>
    <option value="(">(</option>
</select>
Some True/Fale here
<select rel="CloseBracket" id="close2">
    <option value=""></option>
    <option value=")">)</option>
</select>
<button onclick="javascript:TestingRules();">Check</button>

---

function GetOpenBrackets() {
    var openBracketArray = [];
    jQuery('[rel="OpenBracket"]').each(function() {
        if (jQuery(this).val() == "(") {
            openBracketArray.push(jQuery(this).attr('id'));
        } else {
            openBracketArray.push(jQuery(this).val());
        }

    });
    return openBracketArray;
}

function GetCloseBrackets() {
    var closeBracketArray = [];
    jQuery('[rel="CloseBracket"]').each(function() {
        if (jQuery(this).val() == "(") {
            closeBracketArray.push(jQuery(this).attr('id'));
        } else {
            closeBracketArray.push(jQuery(this).val());
        }
    });
    return closeBracketArray;
}
function TestingRules() {
    var openBrackets = GetOpenBrackets();
    var closeBrackets = GetCloseBrackets();
    var closeBracketIndex;
    var openBracketIndex;
    for (openBracketIndex in openBrackets) {
        if (openBrackets[openBracketIndex] !== "") {

            var foundCloseBracketIndex = -1;
            for (closeBracketIndex in closeBrackets) {
                if (openBracketIndex <= closeBracketIndex) {
                    if (closeBrackets[closeBracketIndex] !== "") {
                        foundCloseBracketIndex = closeBracketIndex;
                        break;
                    }
                }
            }
            if (foundCloseBracketIndex > -1) {
            var openBracketCheck;
                for (openBracketCheck in openBrackets) {

                    if (openBracketIndex < openBracketCheck && closeBracketIndex >= openBracketCheck) {
                        if (openBrackets[openBracketCheck] !== "") {
                            alert('error');
                        }
                    }

                }
            }
        }

    }

    // for testing:
    //  console.log(OpenBracketArray.length);
}

Answer 1

Why not just keep a counter, or count paren stack depth? If you inc for open parens, dec for closing, and the counter goes above 1, you have an error. (If I’ve understood your requirements correctly.)