How can I extract data from a string using another string as a template?

Question

I am looking for an efficient way to generically extract data from a string using another string as a template. Pseudocode:

var mystring = \"NET,1:1,0,ipv4,192.1         


        

Answer 1

One solution is at http://jsfiddle.net/CrossEye/Kxe6W/

var templatizedStringParser = function(myTemplate, myString) {

    var names = [];
    var parts = myTemplate.replace( /\[([^\]]+)]/g, function(str, name) {
        names.push(name);
        return "~";
    }).split("~");

    var parser = function(myString) {
        var result = {};
        remainder = myString;
        var i, len, index;
        for (i = 0, len = names.length; i < len; i++) {
            remainder = remainder.substring(parts[i].length);
            index = remainder.indexOf(parts[i + 1]);
            result[names[i]] = remainder.substring(0, index);
            remainder = remainder.substring(index);
        }
        result[names[names.length - 1]] = remainder;
        return result;
    };

    return myString ? parser(myString) : parser;
};

You can use it like this

console.log(templatizedStringParser(myTemplate, myString));

or this:

var parser = templatizedStringParser(myTemplate);
console.log(parser(myString));

There is almost certainly some cruft in there as I did this in a hurry. The use of the "~" might not work for you. And there are likely other problems if you have boundary issues, but it might cover many cases. ​

Answer 2

//This method obtains each lable in the template string
function getLables(patt, templateStr) {
    var i = 0;
    var tmp = patt.exec(templateStr);
    var lables = new Array();
    while(tmp) {
        lables[i] = new String(tmp).replace("[", "").replace("]", "");
        tmp = patt.exec(templateStr);
        ++i;
    }
    return lables;
}

function extract(_inputStr, _template) {
    //Supposing the start string in template is NET
    var startStr = "NET";
    var inputStr = _inputStr.replace(startStr, "");
    var template = "";

    //You can add a control on the correctness of the template
    if(_template.indexOf(startStr) != 0) {
        return false;
        //you could use a throw clausole, in order to use exceptions
    } else {
        template = _template.replace(startStr, "");
    }

    var patt = /\[[a-z | _]+\]/ig; //Pattern to recognize each [lable]
    var delim = template.replace(patt, "[]").split("[]"); //Delimiter list
    var lable = getLables(patt, template); //Lables list
    var result = new Object();

    var endIndex;
    for(var i=0; i<lable.length; ++i) {
        inputStr = inputStr.replace(delim[i], "");
        endIndex = inputStr.indexOf(delim[i+1]);

        if( (i+1) == lable.length ) {
            result[lable[i]] = inputStr.substring(0, inputStr.length);
        } else {
            result[lable[i]] = inputStr.substring(0, endIndex)
            inputStr = inputStr.replace(result[lable[i]], "");
        }

    }

    return result;
}

In this example:

var template = "NET???[one]/[two]";
var inputStr = "NET???test/8";

JSON.stringify(extract(inputStr, template));

The result is:

{
    "one":"test",
    "two":"8"
}