String parsing with quotes

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So, I worked on an interesting problem today - parsing iCal feeds. My desire to parse iCal feeds stems from the fact that I want to translate an iCal feed to an RSS feed. This would let me turn a calendar into an RSS feed that can be added to for example. (Obviously you would only publish events in the future.)

So, working on this I ran into an interesting issue. I needed to parse a string that looked a bit like this:


Everything after the colon was data. Everything before the data is considered params. There are two ways we can make this crazy. First off - the params side can have colons too - if they are in quotes, and not just ":", but...


Let's make things interesting again - you can have multiple params if you separate them by commas - but again, commas can be inside quotes:


Now - as we all know - ColdFusion has some nifty string parsing functions. The list functions are especially useful for cutting up strings, but in this case, are useless. What I ended up doing then was writing a UDF called: findNotInQuotes. Here it is:

function findNotInQuotes(data,target) {
   var inQuotes = false;
   var x = 1;
   var c ="";
   if(arraylen(arguments) gte 3) x = arguments[3];
   for(; x lte len(data); x=x+1) {
      c = mid(data,x,1);
      if(c is"""") {
         if(inQuotes) inQuotes=false;
         else inQuotes = true;
      if(c is target and not inQuotes) return x;
   return 0;

This worked for me, and I was able to write a conditional loop. However - I think it could be done better. My first thought was - why not rewrite all the list functions so they will ignore delimiters in quotes. This seems a bit crazy. Instead - why not simply write a function that will "split" a string into an array, using your delimiters (and why not allow for delimiters of multi-chars, something CF doesn't let you do). Then you can simply loop over the array.

Any thoughts on this?

For those interested in the iCal code - I've got it working, but I want to convert it to a nice CFC first. There are a set of helper functions also included with it so you can parse their time formats. I'm also going to add a function so you can pass in an iCal start date and an iCal duration value and get an end date.

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About Raymond Camden

Raymond is a developer advocate for HERE Technologies. He focuses on JavaScript, serverless and enterprise cat demos. If you like this article, please consider visiting my Amazon Wishlist or donating via PayPal to show your support. You can even buy me a coffee!

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