context-free

Technically, byte-strings (and nested comments) mean the lexer is not regular, but the grammar is still context-free.

Couldn't figure out how to say it well before because they are still not equivalent to context-free languages, they are just sometimes powerful enough to describe some of the context-free languages.

The idea is that by sticking to context-free grammars, protocols will be easier to parse, and the bulk of memory corruption errors can eliminated.

Why does it matter whether the exchange format is a regular or a context-free language?

I've always understood it to be this: A lexer is for a regular language (in the formal sense), whereas a parser is for a context-sensitive (or context-free) language.

Note that I never said that Rust reads a file more than once, or that Rust's grammar is not context-free.

I'm saying that people live in the real world with real contexts, not in Context-Free-Abstraction-Land.

Nom can handle easily regular, context-free and context sensitive grammars (a lot of binary formats are a bit context sensitive, so that was a requirement).

I found these structures cropping up alongside Horn clauses, and Context-Free Grammars in interesting ways.

What do you lose by sticking to context-free grammars?

I alse think the Great Firewall of China did simple context-free regex searches that would have caught the text in the JavaScript literals.

BTW the C grammar is not context-free either.

To sum it all up: most "regular expression" implementations are actually powerful enough to describe context-free grammars, which are essentially regular expressions mixed with balanced parentheses.

Here is a regex that decides if the number is a prime: perl -lne '(1x$_)!~ /^1?$|^(11+?)\1+$/ && print "$_ is prime"' This goes beyond context-free, therefore I couldn't just say "context-free" carelessly in the article.

The fact that the author manages to never use the term "context-free grammar" leads me to believe he's unduly surprised at his discovery.