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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),
}
}
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