Assertions, implemented in late 2021, are certainly an important feature in CongoCC — actually pretty much essential when writing grammars for very gnarly languages. However, as currently implemented, they are admittedly a somewhat strange hybrid construct. The main reason for this is that ASSERT has completely different semantics depending on whether you hit the assertion …
Revisiting Assertions, introducing the ENSURE keyword Read More »
I was trying to think back to when most students are introduced to basic algebra. A typical sort of exercise is simplifying unnecessarily complex expressions, so he can rewrite: (x + 1)y -y as: xy Well, regardless of the exact age when people first see such things, this is part of a typical middle school …
(*Note that this article is largely superseded by the one here) JavaCC 21 now has assertions. There are actually two kinds of assertions: The assertion condition is expressed in Java code. The assertion condition is a lookahead expansion. The first kind of condition looks like this: ASSERT {someCondition()} Optionally, the assertion can have a message, …