TwimlResponse.js

//Public interface is a Response node with the initial set of TwiML child nodes available
/**
    Create a TwiML response, which can later be serialized to XML. 
    
    @return {object} response TwiML Node

*/
var TwimlResponse = function() {

    // Escape XML entites in a given string
    function esc(str) {
        return String(str).replace(/&/g, '&')
            .replace(/\"/g, '"')
            .replace(/\'/g, ''')
            .replace(/</g, '&lt;')
            .replace(/>/g, '&gt;');
    }
    
    //helper to generate a helper function which returns XML node for a given parent
    function addTwimlFunction(node, twimlName) {
        //Generate a function on the parent node
        node[twimlName.charAt(0).toLowerCase() + twimlName.slice(1)] = function() {
            var text, attributes, builder, legalNodes = [];
    
            //Get XML components from the caller
            for (var i = 0, l = arguments.length; i < l; i++) {
                var arg = arguments[i];
                if (typeof arg === 'string') {
                    text = arg;
                }
                else if (typeof arg === 'function') {
                    builder = arg;
                }
                else {
                    attributes = arg;
                }
            }
    
            //determine legal sub-nodes based on the node name
            switch(twimlName) {
                case 'Gather': legalNodes = ['Say','Play','Pause']; break;
                case 'Dial': legalNodes = ['Number','Client','Conference','Queue','Sip']; break;
                default: break;
            }
    
            //create new node object
            var newNode = new Node({
                name:twimlName,
                attributes:attributes,
                text:text,
                legalNodes:legalNodes
            });
    
            //create node's API for subnodes and call builder function, if need be
            if (!text && legalNodes.length > 0 && builder) {
                legalNodes.forEach(function(legalNodeName) {
                    addTwimlFunction(newNode, legalNodeName);
                });
                builder.call(newNode, newNode);
            }
    
            //Assemble the proper XML node and add to parent node
            node.children.push(newNode);
    
            //return the node, to allow for chaining
            return node;
        };
    }
    
    /**
    A TwiML response node - nestable with other TwiML nodes
    
    @param {object} config - options for HTTP request
    - name {string}: name of this node
    - attributes {object}: key-value pairs for XML attributes for this node
    - text {string}: text content, if any, for this node
    - topLevel {boolean}: indicates a top level node which should also print an XML instruction
    - legalNodes {array<string>}: a list of child functions which should be allowable for this node
    */
    function Node(config) {
        _.extend(this,config);
        this.children = [];
    
        //create child adder functions based on legal nodes
        var that = this;
        this.legalNodes.forEach(function(val) {
            addTwimlFunction(that,val);
        });
    }
    
    //Output the contents of this XML node as a string
    Node.prototype.toString = function() {
        var buffer = [];
        if (this.topLevel) {
            buffer.push('<?xml version="1.0" encoding="UTF-8"?>');
        }
    
        //Start node
        buffer.push('<'+this.name);
    
        //handle attributes
        for (var attr in this.attributes) {
            buffer.push(' ' + attr + '="' + esc(this.attributes[attr]) + '"');
        }
    
        //Close start tag
        buffer.push('>');
    
        //process contents of tag
        if (this.text) {
            buffer.push(esc(this.text));
        }
        else {
            //process child tags
            for (var i = 0, l = this.children.length; i < l; i++) {
                buffer.push(this.children[i]);
            }
        }
    
        //close tag
        buffer.push('</'+this.name+'>');
    
        return buffer.join('');
    };



    return new Node({
        topLevel:true,
        name:'Response',
        legalNodes:['Say', 'Play', 'Gather', 'Record', 'Sms', 'Dial', 'Enqueue', 'Leave', 'Hangup', 'Redirect', 'Reject', 'Pause']
    });
};