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use super::*;
pub(super) fn pattern(p: &mut Parser) {
let la0 = p.nth(0);
let la1 = p.nth(1);
if la0 == REF_KW || la0 == MUT_KW
|| (la0 == IDENT && !(la1 == COLONCOLON || la1 == L_PAREN || la1 == L_CURLY)) {
bind_pat(p, true);
return;
}
if paths::is_path_start(p) {
path_pat(p);
return;
}
match la0 {
UNDERSCORE => placeholder_pat(p),
AMP => ref_pat(p),
L_PAREN => tuple_pat(p),
_ => p.err_and_bump("expected pattern"),
}
}
// test path_part
// fn foo() {
// let foo::Bar = ();
// let ::Bar = ();
// let Bar { .. } = ();
// let Bar(..) = ();
// }
fn path_pat(p: &mut Parser) {
let m = p.start();
paths::expr_path(p);
let kind = match p.current() {
L_PAREN => {
tuple_pat_fields(p);
TUPLE_STRUCT_PAT
}
L_CURLY => {
struct_pat_fields(p);
STRUCT_PAT
}
_ => PATH_PAT
};
m.complete(p, kind);
}
// test tuple_pat_fields
// fn foo() {
// let S() = ();
// let S(_) = ();
// let S(_,) = ();
// let S(_, .. , x) = ();
// }
fn tuple_pat_fields(p: &mut Parser) {
assert!(p.at(L_PAREN));
p.bump();
while !p.at(EOF) && !p.at(R_PAREN) {
match p.current() {
DOTDOT => p.bump(),
_ => pattern(p),
}
if !p.at(R_PAREN) {
p.expect(COMMA);
}
}
p.expect(R_PAREN);
}
// test struct_pat_fields
// fn foo() {
// let S {} = ();
// let S { f, ref mut g } = ();
// let S { h: _, ..} = ();
// let S { h: _, } = ();
// }
fn struct_pat_fields(p: &mut Parser) {
assert!(p.at(L_CURLY));
p.bump();
while !p.at(EOF) && !p.at(R_CURLY) {
match p.current() {
DOTDOT => p.bump(),
IDENT if p.nth(1) == COLON => {
p.bump();
p.bump();
pattern(p);
}
_ => bind_pat(p, false),
}
if !p.at(R_CURLY) {
p.expect(COMMA);
}
}
p.expect(R_CURLY);
}
// test placeholder_pat
// fn main() { let _ = (); }
fn placeholder_pat(p: &mut Parser) {
assert!(p.at(UNDERSCORE));
let m = p.start();
p.bump();
m.complete(p, PLACEHOLDER_PAT);
}
// test ref_pat
// fn main() {
// let &a = ();
// let &mut b = ();
// }
fn ref_pat(p: &mut Parser) {
assert!(p.at(AMP));
let m = p.start();
p.bump();
p.eat(MUT_KW);
pattern(p);
m.complete(p, REF_PAT);
}
// test tuple_pat
// fn main() {
// let (a, b, ..) = ();
// }
fn tuple_pat(p: &mut Parser) {
assert!(p.at(L_PAREN));
let m = p.start();
tuple_pat_fields(p);
m.complete(p, TUPLE_PAT);
}
// test bind_pat
// fn main() {
// let a = ();
// let mut b = ();
// let ref c = ();
// let ref mut d = ();
// let e @ _ = ();
// let ref mut f @ g @ _ = ();
// }
fn bind_pat(p: &mut Parser, with_at: bool) {
let m = p.start();
p.eat(REF_KW);
p.eat(MUT_KW);
name(p);
if with_at && p.eat(AT) {
pattern(p);
}
m.complete(p, BIND_PAT);
}
|
