Parse Penn Treebank strings into nodes and edges, easy to render with d3

gistfile1.js

function pennTreeParse(penn_string) {
  
    function eatWhiteSpace(s) {
        while (s.length && /\s/.test(s[0])) s = s.slice(1);
        return s;
    }

    function isCharacter(c) {
        return /^[a-z0-9ÀÈÌÒÙàèìòùÁÉÍÓÚÝáéíóúýÂÊÎÔÛâêîôûÃÑÕãñõÄËÏÖÜäëïöüçÇßØøÅåÆæÞþÐð]+/i.test( c );
    }

    function isPunctuation(c) {
        return /^[\'\?\.,-\/#!$%\^&\*;:{}=\-_`~]+/i.test( c );; // remember not to put parens in here
    }

    function isCorP (c) {
        return isCharacter(c) || isPunctuation(c);
    }

    function getToken(s) {
        var result = {'token': '', 'remainder': s};
        while (s.length && isCorP(s[0])  ) {
            result.token += s[0];
            s = s.slice(1);
        }
        result.remainder = s;
        return result;
    }

    function parsePenn(nodes, edges, parent, num, penn_string) {

        while ((penn_string = eatWhiteSpace(penn_string)).length > 0) {

            if (penn_string[0] == ')') {
                return {'num': num, 'remainder': penn_string.slice(1)};
            }

            var node_class = 'leaf';

            if (penn_string[0] == '(') {
                node_class = 'interior';
                penn_string = penn_string.slice(1)
            }
            var result = getToken(penn_string);

            // use result.token + '-' + '{0}'.f(num) to put the node number in the title
            nodes.push({id: num, label: result.token, reflexive: false});
            if (parent != -1) {
                edges.push({source: nodes[parent], target: nodes[num], left: false, right: true });
            }

            if (node_class == 'leaf') {
                num = num + 1;
                penn_string = penn_string.slice(result.token.length);
            }
            else {
                result = parsePenn(nodes, edges, num, num + 1, result.remainder);

                num = result.num;
                penn_string = result.remainder;
            }
        }
        return {'num': num, 'remainder': ''};
    }

    var nodes = [], edges = []
    parsePenn(nodes, edges, -1, 0, penn_string);
    return {nodes:nodes, edges: edges};
}