Eniko (moved ➡ gamedev.place)goddamn writing a recursive descent parser is a lot harder when you wanna do good syntax error recovery
Doug Gregor@eniko @thephd We’ve recently been rewriting the Swift parser, and have some opinions on how to do this well: good parser primitives (“expect this”, “match this”, “don’t go beyond that”, etc.), no diagnostics from parsing itself (represent all issues as missing/unexpected nodes in the tree), and handle diagnostics in a post-pass. The result is really nice and is easy to extend to@new grammar terms. See https://github.com/apple/swift-syntax/blob/main/Sources/SwiftParser/SwiftParser.docc/ParserRecovery.md
mirabilos@eniko @dgregor79 @thephd oooh interesting. I fear this works better for languages structured like C than like Korn Shell though, right?
@mirabilos @eniko @thephd C is tricky because it’s ambiguous without doing name lookup, but beyond that—I think this works as long as you have a grammar to work with. Swift needs a bit of look ahead to resolve ambiguities, and that works fine
@dgregor79 @eniko @thephd yeah, for shell, even just POSIX shell, grammar is… a thing. Some things parse very differently depending on context.