What was Tim Sweeney thinking? (How does this C++ parser work?)
- by Frank Krueger
Tim Sweeney of Epic MegaGames is the lead developer for Unreal and a programming language geek. Many years ago posted the following screen shot to VoodooExtreme:
As a C++ programmer and Sweeney fan, I was captivated by this. It shows generic C++ code that implements some kind of scripting language where that language itself seems to be generic in the sense that it can define its own grammar.
Mr. Sweeney never explained himself. :-)
It's rare to see this level of template programming, but you do see it from time to time when people want to push the compiler to generate great code or because they want to create generic code (for example, Modern C++ Design).
Tim seems to be using it to create a grammar in Parser.cpp - you can see what look like prioritized binary operators. If that is the case, then why does Test.ae look like it's also defining a grammar?
Obviously this is a puzzle that needs to be solved. Victory goes to the answer with a working version of this code, or the most plausible explanation, or to Tim Sweeney himself if he posts an answer. :-)
