Function syntax::ext::tt::macro_parser::may_begin_with[][src]

fn may_begin_with(name: &str, token: &Token) -> bool
🔬 This is a nightly-only experimental API. (rustc_private)

this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via Cargo.toml instead?

Checks whether a non-terminal may begin with a particular token.

Returning false is a stability guarantee that such a matcher will never begin with that token. Be conservative (return true) if not sure.