• The XML file is in a custom format
• Everything is parsed into an array
• The parsing is tied to a specific XML structure
• It is not very expandable
• There was code everywhere

Contents

• Using defined RSS XML news feed standard
• Reducing the amount of code by parsing into an array
• Calling the extractData function
• The showText routine
• The parseTree function
• The extractItem function

The parseTree function is a recursive function call, a node is passed to the parseTree function, if that node contains other nodes then each of those childNodes are checked by a new instance of the parsTree function to see if they are an item node. The for loop is used to go through each child node one at a time. I have left the trace statement in so it is easy to check that the system is parsing the entire XML file. If we encounter an item node we will call the extractItem function. If we encounter anything else we will call the parseTree function again.

If you haven't programmed with recursive functions call this can be a bit of mind bender and can be tricky to debug. However this method of parsing XML files is great if you are not in control of the format of the XML file. Flash can make up to 256 recursive calls before its call stack (the thing to keep track of which functions have called other functions) is full. In a practical sense this means that we can parse a XML file that is up to 250 or so nodes deep (eg firstNode.firstNode.firstNode would be 3 nodes deep), I doubt there are many XML files out there that have a node heirachy greater than 250 nodes deep. Note: this is not how many nodes and XML file has but how many parents a node has. Most XML files are 2-6 nodes deep and complicated XML files might have a hierachy with more than 10 nodes. 250 nodes seems would be an extremely complicated XML file.

function parseTree(xmlNode)
{
        //Go through each node, if it is an item node then add items to the itemsArray
        //Else go through each of the child nodes and recursively call this function
        //foreach child node. Note item nodes inside other item nodes will not be found.

        trace("Parsing this: " + xmlNode.toString()); //Used for initial debugging to make sure xml parsing is working.

        if (xmlNode.hasChildNodes())
        {
            //Something funny in the parsing here.
            for (var i = 0; i < xmlNode.childNodes.length; i++)
            {
                trace("xmlNode.childNodes[" + i + "].nodeName: " +xmlNode.childNodes[i].nodeName);
                if (xmlNode.childNodes[i].nodeName == "item")
                {
                        //Extract the RSS item
                        extractItem(xmlNode.childNodes[i]);
                } else
                {
                        //Call parseTree to scavenge through this nodes childNodes
                        parseTree(xmlNode.childNodes[i]);
                }
            }
        }
}

(lines 37-63)