Javascript - String.split(regex) Keep Separators

I would like to split a string using a regular expression and have the separators / matched info included in the resulting array. In java I used: theString.split('(?<=[!><

Solution 1:

If you put the whole pattern in a group, you will also get the separators:

thestr.split(/([!><=}{]| (?:AND|OR) )/)

This returns an array like:

["Reason", "=", "", "{", "Existing problem or fault", "}", "", "{", "Bestaande probleem of vout", "}", "", "{", "Other", "}", "", "{", "Ander", "}", " and Required", "!", "", "=", "No and Results ", ">", "", "=", "10 and Results ", "<", "", "=", "25 and Tst", ">", "5 and Tst", "<", "80 and Info", "=", "test this or that and those and Success", "!", "", "=", "Yes"]

Then you just need to filter the empty strings and you’re done:

thestr.split(/([!><=}{]| (?:AND|OR) )/).filter(Boolean)

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Edit    Since Internet Explorer and possibly other browsers do not take a grouped separator into the result array, you could do this instead:

var matches = thestr.split(/(?:[!><=}{]| (?:AND|OR) )/),
    separators = thestr.match(/(?:[!><=}{]| (?:AND|OR) )/g);
for (var i=0; i<separators.length; ++i) {
    matches[i+1] = separators[i];
}

This basically separates the separators from the other parts and then combines both.

Solution 2:

Not getting too deep into your query structure, I would suggest you to use replace method with a function as replacement which would collect the terms into an array:

function parse(sQuery) {
    var aParsed = [];
    var oReTerms = /.../gim;
    sQuery.replace(oReTerms, function($0, $1, $2, ...) {
        //...
        if ($1) {
            aParsed.append($1);
        }
        if ($2) {
            aParsed.append($2);
        }
        //...
        return $0; // return what was matched (or any string)
    });
    return aParsed;
}

I did this previously to parse HTML tags and attributes. I hope the idea is clear. You just need to define your regular expression so that it matches all terms in the query.

And you can have another replacing within the replacement function for specific cases.

Solution 3:

I'm not sure about how JavaScript behaves if a regex split contains a capturing group. I know that in Python, a splitting delimiter becomes part of the match if it is enclosed in capturing parentheses.

Try

result = subject.split(/( or )|( and )|([^\w\s])\b|(?=[^\w\s])/i);

and see what happens.

Solution 4:

function split2(str, re) {
    if (re.global) {
        // Reset to start of string
        re.lastIndex = 0;
    }
    var result = [];
    var match = re.exec(str);
    var lastEnd = 0;
    while (match != null) {
        if (match.index > lastEnd) {
            result.push(str.substring(lastEnd, match.index));
        }
        result.push(match[0]);
        lastEnd = match.index + match[0].length;
        match = re.exec(str);
    }
    result.push(str.substring(lastEnd));
    return result;
}

var thestr = "Reason={Existing problem or fault}{Bestaande probleem of vout}{Other}{Ander} and Required!=No and Results >=10 and Results <=25 and Tst>5 and Tst<80 and Info=test this or that and those and Success!=Yes";

var patt = /[!><=}{]| AND | OR /gi;

split2(thestr,patt):

Output:

["Reason", "=", "{", "Existing problem", " or ", "fault", "}", "{",
"Bestaande probleem of vout", "}", "{", "Other", "}", "{", "Ander", "}", " and ",
"Required", "!", "=", "No", " and ", "Results ", ">", "=", "10", " and ",
"Results ", "<", "=", "25", " and ", "Tst", ">", "5", " and ", "Tst", "<", "80",
" and ", "Info", "=", "test this", " or ", "that", " and ", "those", " and ",
"Success", "!", "=", "Yes"]

Solution 5:

Gumbo's split function above is a good idea but it doesn't work. It should be:

function split(str, regex) {
    var matches    = str.split(regex),
        separators = str.match(regex),
        ret        = [ matches[0] ];
    if (!separators) return ret;
    for (var i = 0; i < separators.length; ++i) {
        ret[2 * i + 1] = separators[i];
        ret[2 * i + 2] = matches[i + 1];
    }
    return ret;
}

split('a,b,c', /,/g); // returns ["a", ",", "b", ",", "c"]