One of the great things about the new Flex open source project, is that it isn’t just the framework that has been opened up. We have even pulled back the covers on the compiler. Today, Matt Chotin posted on the open source wiki what used to be an internal document that describes how the Flex compiler, usually known as mxmlc, is architected. So if you are looking to hack around on the compiler, fix bugs, or even add functionality, check out that link.
You may be wondering to yourself though, what can I actually do with this information? One great example is the new Flex code coverage tool called Flex Cover written by Joe Berkovitz. The tool basically adds functionality to the Flex compiler so that the bytecode it outputs contains information about what code has been executed. You can then take this information to generate a report which allows you to see which lines of your ActionScript code actually executed during that session.
So what are you thinking of using this information for? How about instrumenting the compiler to do some code optimization? Or maybe just fix that compiler bug that keeps annoying you? How about adding an entirely new feature to Flex? Now that it is all open source, go ahead and try it out!