use super::*; pub(super) const PATTERN_FIRST: TokenSet = token_set_union![ token_set![REF_KW, MUT_KW, L_PAREN, L_BRACK, AMP, UNDERSCORE], expressions::LITERAL_FIRST, paths::PATH_FIRST, ]; pub(super) fn pattern(p: &mut Parser) { pattern_r(p, PAT_RECOVERY_SET) } pub(super) fn pattern_r(p: &mut Parser, recovery_set: TokenSet) { if let Some(lhs) = atom_pat(p, recovery_set) { // test range_pat // fn main() { // match 92 { 0 ... 100 => () } // } if p.at(DOTDOTDOT) { let m = lhs.precede(p); p.bump(); atom_pat(p, recovery_set); m.complete(p, RANGE_PAT); } } } const PAT_RECOVERY_SET: TokenSet = token_set![LET_KW, IF_KW, WHILE_KW, LOOP_KW, MATCH_KW, R_PAREN, COMMA]; fn atom_pat(p: &mut Parser, recovery_set: TokenSet) -> Option { 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)) { return Some(bind_pat(p, true)); } if paths::is_path_start(p) { return Some(path_pat(p)); } // test literal_pattern // fn main() { // match () { // 92 => (), // 'c' => (), // "hello" => (), // } // } match expressions::literal(p) { Some(m) => return Some(m), None => (), } let m = match la0 { UNDERSCORE => placeholder_pat(p), AMP => ref_pat(p), L_PAREN => tuple_pat(p), L_BRACK => slice_pat(p), _ => { p.err_recover("expected pattern", recovery_set); return None; } }; Some(m) } // test path_part // fn foo() { // let foo::Bar = (); // let ::Bar = (); // let Bar { .. } = (); // let Bar(..) = (); // } fn path_pat(p: &mut Parser) -> CompletedMarker { assert!(paths::is_path_start(p)); let m = p.start(); paths::expr_path(p); let kind = match p.current() { L_PAREN => { tuple_pat_fields(p); TUPLE_STRUCT_PAT } L_CURLY => { field_pat_list(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(), _ => { if !p.at_ts(PATTERN_FIRST) { p.error("expected a pattern"); break; } pattern(p) } } if !p.at(R_PAREN) { p.expect(COMMA); } } p.expect(R_PAREN); } // test field_pat_list // fn foo() { // let S {} = (); // let S { f, ref mut g } = (); // let S { h: _, ..} = (); // let S { h: _, } = (); // } fn field_pat_list(p: &mut Parser) { assert!(p.at(L_CURLY)); let m = p.start(); 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); } L_CURLY => error_block(p, "expected ident"), _ => { bind_pat(p, false); } } if !p.at(R_CURLY) { p.expect(COMMA); } } p.expect(R_CURLY); m.complete(p, FIELD_PAT_LIST); } // test placeholder_pat // fn main() { let _ = (); } fn placeholder_pat(p: &mut Parser) -> CompletedMarker { 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) -> CompletedMarker { 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) -> CompletedMarker { assert!(p.at(L_PAREN)); let m = p.start(); tuple_pat_fields(p); m.complete(p, TUPLE_PAT) } // test slice_pat // fn main() { // let [a, b, ..] = []; // } fn slice_pat(p: &mut Parser) -> CompletedMarker { assert!(p.at(L_BRACK)); let m = p.start(); p.bump(); while !p.at(EOF) && !p.at(R_BRACK) { match p.current() { DOTDOT => p.bump(), _ => pattern(p), } if !p.at(R_BRACK) { p.expect(COMMA); } } p.expect(R_BRACK); m.complete(p, SLICE_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) -> CompletedMarker { 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) }