index.js

// a simple parser for Valve's KeyValue format
// https://developer.valvesoftware.com/wiki/KeyValues
//
// author: Rossen Popov, 2014-2016

function parse(text) {
    if(typeof text != "string") {
        throw new TypeError("VDF.parse: Expecting parameter to be a string");
    }

    lines = text.split("\n");

    var obj = {};
    var stack = [obj];
    var expect_bracket = false;
    var name = "";

    var re_kv = new RegExp(
        '^("((?:\\\\.|[^\\\\"])+)"|([a-z0-9\\-\\_]+))' +
        '([ \t]*(' +
        '"((?:\\\\.|[^\\\\"])*)(")?' +
        '|([a-z0-9\\-\\_]+)' +
        '))?'
        );

    var i = 0, j = lines.length;
    for(; i < j; i++) {
        line = lines[i].trim();

        // skip empty and comment lines
        if( line == "" || line[0] == '/') { continue; }

        // one level deeper
        if( line[0] == "{" ) {
            expect_bracket = false;
            continue;
        }

        if(expect_bracket) {
            throw new SyntaxError("VDF.parse: invalid syntax on line " + (i+1));
        }

        // one level back
        if( line[0] == "}" ) {
            stack.pop();
            continue;
        }

        // parse keyvalue pairs
        while(true) {
            m = re_kv.exec(line);

            if(m === null) {
                throw new SyntaxError("VDF.parse: invalid syntax on line " + (i+1));
            }

            // qkey = 2
            // key = 3
            // qval = 6
            // vq_end = 7
            // val = 8
            var key = (m[2] !== undefined) ? m[2] : m[3];
            var val = (m[6] !== undefined) ? m[6] : m[8];

            if(val === undefined) {
                // chain (merge) duplicate key
                if(stack[stack.length-1][key] === undefined)
                    stack[stack.length-1][key] = {};

                stack.push(stack[stack.length-1][key]);
                expect_bracket = true;
            }
            else {
                if(m[7] === undefined && m[8] === undefined) {
                    line += "\n" + lines[++i];
                    continue;
                }

                stack[stack.length-1][key] = val;
            }

            break;
        }
    }

    if(stack.length != 1) throw new SyntaxError("VDF.parse: open parentheses somewhere");

    return obj;
}

function stringify(obj,pretty) {
    if( typeof obj != "object") {
            throw new TypeError("VDF.stringify: First input parameter is not an object");
    }

    pretty = ( typeof pretty == "boolean" && pretty) ? true : false;

    return _dump(obj,pretty,0);
}

function _dump(obj,pretty,level) {
    if( typeof obj != "object" ) {
        throw new TypeError("VDF.stringify: a key has value of type other than string or object");
    }

    var indent = "\t";
    var buf = "";
    var line_indent = "";


    if(pretty) {
        for(var i = 0; i < level; i++ ) {
            line_indent += indent;
        }
    }

    for(key in obj) {
        if (obj.hasOwnProperty(key)){
            if( typeof obj[key] == "object" ) {
                buf += [line_indent, '"', key, '"\n', line_indent, '{\n', _dump(obj[key],pretty,level+1), line_indent, "}\n"].join('');
            }
            else {
                buf += [line_indent, '"', key, '" "', String(obj[key]), '"\n'].join('');
            }
        }
    }

    return buf;
}

exports.parse = parse;
exports.stringify = stringify;
exports.dump = stringify;