mod atom; pub(crate) use self::atom::match_arm_list; pub(super) use self::atom::{literal, LITERAL_FIRST}; use super::*; pub(super) enum StmtWithSemi { Yes, No, Optional, } const EXPR_FIRST: TokenSet = LHS_FIRST; pub(super) fn expr(p: &mut Parser) -> BlockLike { let r = Restrictions { forbid_structs: false, prefer_stmt: false }; expr_bp(p, r, 1).1 } pub(super) fn expr_stmt(p: &mut Parser) -> (Option, BlockLike) { let r = Restrictions { forbid_structs: false, prefer_stmt: true }; expr_bp(p, r, 1) } fn expr_no_struct(p: &mut Parser) { let r = Restrictions { forbid_structs: true, prefer_stmt: false }; expr_bp(p, r, 1); } // test block // fn a() {} // fn b() { let _ = 1; } // fn c() { 1; 2; } // fn d() { 1; 2 } pub(crate) fn block(p: &mut Parser) { if !p.at(T!['{']) { p.error("expected a block"); return; } atom::block_expr(p, None); } pub(crate) fn naked_block(p: &mut Parser) { assert!(p.at(T!['{'])); let m = p.start(); p.bump(T!['{']); expr_block_contents(p); p.expect(T!['}']); m.complete(p, BLOCK); } fn is_expr_stmt_attr_allowed(kind: SyntaxKind) -> bool { match kind { BIN_EXPR | RANGE_EXPR | IF_EXPR => false, _ => true, } } pub(super) fn stmt(p: &mut Parser, with_semi: StmtWithSemi) { // test block_items // fn a() { fn b() {} } let m = p.start(); // test attr_on_expr_stmt // fn foo() { // #[A] foo(); // #[B] bar!{} // #[C] #[D] {} // #[D] return (); // } let has_attrs = p.at(T![#]); attributes::outer_attributes(p); if p.at(T![let]) { let_stmt(p, m, with_semi); return; } let m = match items::maybe_item(p, m, items::ItemFlavor::Mod) { Ok(()) => return, Err(m) => m, }; let (cm, blocklike) = expr_stmt(p); let kind = cm.as_ref().map(|cm| cm.kind()).unwrap_or(ERROR); if has_attrs && !is_expr_stmt_attr_allowed(kind) { // test_err attr_on_expr_not_allowed // fn foo() { // #[A] 1 + 2; // #[B] if true {}; // } p.error(format!("attributes are not allowed on {:?}", kind)); } if p.at(T!['}']) { // test attr_on_last_expr_in_block // fn foo() { // { #[A] bar!()? } // #[B] &() // } if let Some(cm) = cm { cm.undo_completion(p).abandon(p); m.complete(p, kind); } else { m.abandon(p); } } else { // test no_semi_after_block // fn foo() { // if true {} // loop {} // match () {} // while true {} // for _ in () {} // {} // {} // macro_rules! test { // () => {} // } // test!{} // } match with_semi { StmtWithSemi::Yes => { if blocklike.is_block() { p.eat(T![;]); } else { p.expect(T![;]); } } StmtWithSemi::No => {} StmtWithSemi::Optional => { if p.at(T![;]) { p.eat(T![;]); } } } m.complete(p, EXPR_STMT); } // test let_stmt // fn foo() { // let a; // let b: i32; // let c = 92; // let d: i32 = 92; // let e: !; // let _: ! = {}; // } fn let_stmt(p: &mut Parser, m: Marker, with_semi: StmtWithSemi) { assert!(p.at(T![let])); p.bump(T![let]); patterns::pattern(p); if p.at(T![:]) { types::ascription(p); } if p.eat(T![=]) { expressions::expr(p); } match with_semi { StmtWithSemi::Yes => { p.expect(T![;]); } StmtWithSemi::No => {} StmtWithSemi::Optional => { if p.at(T![;]) { p.eat(T![;]); } } } m.complete(p, LET_STMT); } } pub(crate) fn expr_block_contents(p: &mut Parser) { // This is checked by a validator attributes::inner_attributes(p); while !p.at(EOF) && !p.at(T!['}']) { // test nocontentexpr // fn foo(){ // ;;;some_expr();;;;{;;;};;;;Ok(()) // } // test nocontentexpr_after_item // fn simple_function() { // enum LocalEnum { // One, // Two, // }; // fn f() {}; // struct S {}; // } if p.at(T![;]) { p.bump(T![;]); continue; } stmt(p, StmtWithSemi::Yes) } } #[derive(Clone, Copy)] struct Restrictions { forbid_structs: bool, prefer_stmt: bool, } /// Binding powers of operators for a Pratt parser. /// /// See https://www.oilshell.org/blog/2016/11/03.html #[rustfmt::skip] fn current_op(p: &Parser) -> (u8, SyntaxKind) { const NOT_AN_OP: (u8, SyntaxKind) = (0, T![@]); match p.current() { T![|] if p.at(T![||]) => (3, T![||]), T![|] if p.at(T![|=]) => (1, T![|=]), T![|] => (6, T![|]), T![>] if p.at(T![>>=]) => (1, T![>>=]), T![>] if p.at(T![>>]) => (9, T![>>]), T![>] if p.at(T![>=]) => (5, T![>=]), T![>] => (5, T![>]), T![=] if p.at(T![=>]) => NOT_AN_OP, T![=] if p.at(T![==]) => (5, T![==]), T![=] => (1, T![=]), T![<] if p.at(T![<=]) => (5, T![<=]), T![<] if p.at(T![<<=]) => (1, T![<<=]), T![<] if p.at(T![<<]) => (9, T![<<]), T![<] => (5, T![<]), T![+] if p.at(T![+=]) => (1, T![+=]), T![+] => (10, T![+]), T![^] if p.at(T![^=]) => (1, T![^=]), T![^] => (7, T![^]), T![%] if p.at(T![%=]) => (1, T![%=]), T![%] => (11, T![%]), T![&] if p.at(T![&=]) => (1, T![&=]), T![&] if p.at(T![&&]) => (4, T![&&]), T![&] => (8, T![&]), T![/] if p.at(T![/=]) => (1, T![/=]), T![/] => (11, T![/]), T![*] if p.at(T![*=]) => (1, T![*=]), T![*] => (11, T![*]), T![.] if p.at(T![..=]) => (2, T![..=]), T![.] if p.at(T![..]) => (2, T![..]), T![!] if p.at(T![!=]) => (5, T![!=]), T![-] if p.at(T![-=]) => (1, T![-=]), T![-] => (10, T![-]), _ => NOT_AN_OP } } // Parses expression with binding power of at least bp. fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) -> (Option, BlockLike) { let mut lhs = match lhs(p, r) { Some((lhs, blocklike)) => { // test stmt_bin_expr_ambiguity // fn foo() { // let _ = {1} & 2; // {1} &2; // } if r.prefer_stmt && blocklike.is_block() { return (Some(lhs), BlockLike::Block); } lhs } None => return (None, BlockLike::NotBlock), }; loop { let is_range = p.at(T![..]) || p.at(T![..=]); let (op_bp, op) = current_op(p); if op_bp < bp { break; } let m = lhs.precede(p); p.bump(op); expr_bp(p, r, op_bp + 1); lhs = m.complete(p, if is_range { RANGE_EXPR } else { BIN_EXPR }); } (Some(lhs), BlockLike::NotBlock) } const LHS_FIRST: TokenSet = atom::ATOM_EXPR_FIRST.union(token_set![AMP, STAR, EXCL, DOT, MINUS]); fn lhs(p: &mut Parser, r: Restrictions) -> Option<(CompletedMarker, BlockLike)> { let m; let kind = match p.current() { // test ref_expr // fn foo() { // let _ = &1; // let _ = &mut &f(); // } T![&] => { m = p.start(); p.bump(T![&]); p.eat(T![mut]); REF_EXPR } // test unary_expr // fn foo() { // **&1; // !!true; // --1; // } T![*] | T![!] | T![-] => { m = p.start(); p.bump_any(); PREFIX_EXPR } _ => { // test full_range_expr // fn foo() { xs[..]; } for &op in [T![..=], T![..]].iter() { if p.at(op) { m = p.start(); p.bump(op); if p.at_ts(EXPR_FIRST) { expr_bp(p, r, 2); } return Some((m.complete(p, RANGE_EXPR), BlockLike::NotBlock)); } } // test expression_after_block // fn foo() { // let mut p = F{x: 5}; // {p}.x = 10; // } // let (lhs, blocklike) = atom::atom_expr(p, r)?; return Some(postfix_expr(p, lhs, blocklike, !(r.prefer_stmt && blocklike.is_block()))); } }; expr_bp(p, r, 255); Some((m.complete(p, kind), BlockLike::NotBlock)) } fn postfix_expr( p: &mut Parser, mut lhs: CompletedMarker, // Calls are disallowed if the type is a block and we prefer statements because the call cannot be disambiguated from a tuple // E.g. `while true {break}();` is parsed as // `while true {break}; ();` mut block_like: BlockLike, mut allow_calls: bool, ) -> (CompletedMarker, BlockLike) { loop { lhs = match p.current() { // test stmt_postfix_expr_ambiguity // fn foo() { // match () { // _ => {} // () => {} // [] => {} // } // } T!['('] if allow_calls => call_expr(p, lhs), T!['['] if allow_calls => index_expr(p, lhs), T![.] => match postfix_dot_expr(p, lhs) { Ok(it) => it, Err(it) => { lhs = it; break; } }, T![?] => try_expr(p, lhs), T![as] => cast_expr(p, lhs), _ => break, }; allow_calls = true; block_like = BlockLike::NotBlock; } return (lhs, block_like); fn postfix_dot_expr( p: &mut Parser, lhs: CompletedMarker, ) -> Result { assert!(p.at(T![.])); if p.nth(1) == IDENT && (p.nth(2) == T!['('] || p.nth_at(2, T![::])) { return Ok(method_call_expr(p, lhs)); } // test await_expr // fn foo() { // x.await; // x.0.await; // x.0().await?.hello(); // } if p.nth(1) == T![await] { let m = lhs.precede(p); p.bump(T![.]); p.bump(T![await]); return Ok(m.complete(p, AWAIT_EXPR)); } // test postfix_range // fn foo() { let x = 1..; } for &(op, la) in [(T![..=], 3), (T![..], 2)].iter() { if p.at(op) { return if EXPR_FIRST.contains(p.nth(la)) { Err(lhs) } else { let m = lhs.precede(p); p.bump(op); Ok(m.complete(p, RANGE_EXPR)) }; } } Ok(field_expr(p, lhs)) } } // test call_expr // fn foo() { // let _ = f(); // let _ = f()(1)(1, 2,); // let _ = f(::func()); // f(::func()); // } fn call_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker { assert!(p.at(T!['('])); let m = lhs.precede(p); arg_list(p); m.complete(p, CALL_EXPR) } // test index_expr // fn foo() { // x[1][2]; // } fn index_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker { assert!(p.at(T!['['])); let m = lhs.precede(p); p.bump(T!['[']); expr(p); p.expect(T![']']); m.complete(p, INDEX_EXPR) } // test method_call_expr // fn foo() { // x.foo(); // y.bar::(1, 2,); // } fn method_call_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker { assert!(p.at(T![.]) && p.nth(1) == IDENT && (p.nth(2) == T!['('] || p.nth_at(2, T![::]))); let m = lhs.precede(p); p.bump_any(); name_ref(p); type_args::opt_type_arg_list(p, true); if p.at(T!['(']) { arg_list(p); } m.complete(p, METHOD_CALL_EXPR) } // test field_expr // fn foo() { // x.foo; // x.0.bar; // x.0(); // } // test_err bad_tuple_index_expr // fn foo() { // x.0.; // x.1i32; // x.0x01; // } #[allow(clippy::if_same_then_else)] fn field_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker { assert!(p.at(T![.])); let m = lhs.precede(p); p.bump(T![.]); if p.at(IDENT) || p.at(INT_NUMBER) { name_ref_or_index(p) } else if p.at(FLOAT_NUMBER) { // FIXME: How to recover and instead parse INT + T![.]? p.bump_any(); } else { p.error("expected field name or number") } m.complete(p, FIELD_EXPR) } // test try_expr // fn foo() { // x?; // } fn try_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker { assert!(p.at(T![?])); let m = lhs.precede(p); p.bump(T![?]); m.complete(p, TRY_EXPR) } // test cast_expr // fn foo() { // 82 as i32; // 81 as i8 + 1; // 79 as i16 - 1; // 0x36 as u8 <= 0x37; // } fn cast_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker { assert!(p.at(T![as])); let m = lhs.precede(p); p.bump(T![as]); // Use type_no_bounds(), because cast expressions are not // allowed to have bounds. types::type_no_bounds(p); m.complete(p, CAST_EXPR) } fn arg_list(p: &mut Parser) { assert!(p.at(T!['('])); let m = p.start(); p.bump(T!['(']); while !p.at(T![')']) && !p.at(EOF) { if !p.at_ts(EXPR_FIRST) { p.error("expected expression"); break; } expr(p); if !p.at(T![')']) && !p.expect(T![,]) { break; } } p.eat(T![')']); m.complete(p, ARG_LIST); } // test path_expr // fn foo() { // let _ = a; // let _ = a::b; // let _ = ::a::; // let _ = format!(); // } fn path_expr(p: &mut Parser, r: Restrictions) -> (CompletedMarker, BlockLike) { assert!(paths::is_path_start(p)); let m = p.start(); paths::expr_path(p); match p.current() { T!['{'] if !r.forbid_structs => { record_field_list(p); (m.complete(p, RECORD_LIT), BlockLike::NotBlock) } T![!] if !p.at(T![!=]) => { let block_like = items::macro_call_after_excl(p); (m.complete(p, MACRO_CALL), block_like) } _ => (m.complete(p, PATH_EXPR), BlockLike::NotBlock), } } // test record_lit // fn foo() { // S {}; // S { x, y: 32, }; // S { x, y: 32, ..Default::default() }; // TupleStruct { 0: 1 }; // } pub(crate) fn record_field_list(p: &mut Parser) { assert!(p.at(T!['{'])); let m = p.start(); p.bump(T!['{']); while !p.at(EOF) && !p.at(T!['}']) { match p.current() { // test record_literal_field_with_attr // fn main() { // S { #[cfg(test)] field: 1 } // } IDENT | INT_NUMBER | T![#] => { let m = p.start(); attributes::outer_attributes(p); name_ref_or_index(p); if p.eat(T![:]) { expr(p); } m.complete(p, RECORD_FIELD); } T![.] if p.at(T![..]) => { p.bump(T![..]); expr(p); } T!['{'] => error_block(p, "expected a field"), _ => p.err_and_bump("expected identifier"), } if !p.at(T!['}']) { p.expect(T![,]); } } p.expect(T!['}']); m.complete(p, RECORD_FIELD_LIST); }