use super::*; pub(super) const PATH_FIRST: TokenSet = token_set![IDENT, SELF_KW, SUPER_KW, CRATE_KW, COLONCOLON, L_ANGLE]; pub(super) fn is_path_start(p: &Parser) -> bool { match p.current() { IDENT | SELF_KW | SUPER_KW | CRATE_KW | COLONCOLON => true, _ => false, } } pub(super) fn use_path(p: &mut Parser) { path(p, Mode::Use) } pub(super) fn type_path(p: &mut Parser) { path(p, Mode::Type) } pub(super) fn expr_path(p: &mut Parser) { path(p, Mode::Expr) } #[derive(Clone, Copy, Eq, PartialEq)] enum Mode { Use, Type, Expr, } fn path(p: &mut Parser, mode: Mode) { let path = p.start(); path_segment(p, mode, true); let mut qual = path.complete(p, PATH); loop { let use_tree = match p.nth(1) { STAR | L_CURLY => true, _ => false, }; if p.at(COLONCOLON) && !use_tree { let path = qual.precede(p); p.bump(); path_segment(p, mode, false); let path = path.complete(p, PATH); qual = path; } else { break; } } } fn path_segment(p: &mut Parser, mode: Mode, first: bool) { let m = p.start(); // test qual_paths // type X = <A as B>::Output; // fn foo() { <usize as Default>::default(); } if first && p.eat(L_ANGLE) { types::type_(p); if p.eat(AS_KW) { if is_path_start(p) { types::path_type(p); } else { p.error("expected a trait"); } } p.expect(R_ANGLE); } else { if first { p.eat(COLONCOLON); } match p.current() { IDENT => { name_ref(p); opt_path_type_args(p, mode); } // test crate_path // use crate::foo; SELF_KW | SUPER_KW | CRATE_KW => p.bump(), _ => { p.err_recover("expected identifier", items::ITEM_RECOVERY_SET); } }; } m.complete(p, PATH_SEGMENT); } fn opt_path_type_args(p: &mut Parser, mode: Mode) { match mode { Mode::Use => return, Mode::Type => { // test path_fn_trait_args // type F = Box<Fn(x: i32) -> ()>; if p.at(L_PAREN) { params::param_list_opt_patterns(p); opt_fn_ret_type(p); } else { type_args::opt_type_arg_list(p, false) } } Mode::Expr => type_args::opt_type_arg_list(p, true), } }