discuss.effbot.org

In the early seventies, Vaughan Pratt published an elegant improvement to recursive-descent in his paper Top-down Operator Precedence. Pratt's algorithm associates semantics with tokens instead of grammar rules, and uses a simple 'binding power' mechanism to handle precedence levels. /.../ In this article, I'll briefly explain how the algorithm works, discuss different ways to implement interpreters and translators with it in Python, and finally use it to implement a parser for Python's expression syntax.

"The essence of pretty code is that one can infer much about the code's structure from a glance, without completely reading it. I call this "visual parsing": discerning the flow and relative importance of code from its shape. Engineering such code requires a certain amount of artifice to transform otherwise working code into working, readable code, making the extra step to leave visual cues for the user, not the compiler."