mod atom; pub(crate) use self::atom::match_arm_list; pub(super) use self::atom::{literal, LITERAL_FIRST}; use super::*; 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) } pub(super) fn expr_stmt(p: &mut Parser) -> 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(L_CURLY) { p.error("expected a block"); return; } let m = p.start(); p.bump(); expr_block_contents(p); p.expect(R_CURLY); m.complete(p, BLOCK); } 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(R_CURLY) { match p.current() { // test nocontentexpr // fn foo(){ // ;;;some_expr();;;;{;;;};;;;Ok(()) // } SEMI => p.bump(), _ => { // test block_items // fn a() { fn b() {} } let m = p.start(); let has_attrs = p.at(POUND); attributes::outer_attributes(p); if p.at(LET_KW) { let_stmt(p, m); } else { match items::maybe_item(p, items::ItemFlavor::Mod) { items::MaybeItem::Item(kind) => { m.complete(p, kind); } items::MaybeItem::Modifiers => { m.abandon(p); p.error("expected an item"); } // test pub_expr // fn foo() { pub 92; } //FIXME items::MaybeItem::None => { if has_attrs { m.abandon(p); p.error( "expected a let statement or an item after attributes in block", ); } else { let is_blocklike = expressions::expr_stmt(p) == BlockLike::Block; if p.at(R_CURLY) { m.abandon(p); } else { // test no_semi_after_block // fn foo() { // if true {} // loop {} // match () {} // while true {} // for _ in () {} // {} // {} // macro_rules! test { // () => {} // } // test!{} // } if is_blocklike { p.eat(SEMI); } else { p.expect(SEMI); } m.complete(p, EXPR_STMT); } } } } } } } } // test let_stmt; // fn foo() { // let a; // let b: i32; // let c = 92; // let d: i32 = 92; // } fn let_stmt(p: &mut Parser, m: Marker) { assert!(p.at(LET_KW)); p.bump(); patterns::pattern(p); if p.at(COLON) { types::ascription(p); } if p.eat(EQ) { expressions::expr(p); } p.expect(SEMI); m.complete(p, LET_STMT); } } #[derive(Clone, Copy)] struct Restrictions { forbid_structs: bool, prefer_stmt: bool, } enum Op { Simple, Composite(SyntaxKind, u8), } fn current_op(p: &Parser) -> (u8, Op) { if let Some(t) = p.current3() { match t { (L_ANGLE, L_ANGLE, EQ) => return (1, Op::Composite(SHLEQ, 3)), (R_ANGLE, R_ANGLE, EQ) => return (1, Op::Composite(SHREQ, 3)), _ => (), } } if let Some(t) = p.current2() { match t { (PLUS, EQ) => return (1, Op::Composite(PLUSEQ, 2)), (MINUS, EQ) => return (1, Op::Composite(MINUSEQ, 2)), (STAR, EQ) => return (1, Op::Composite(STAREQ, 2)), (SLASH, EQ) => return (1, Op::Composite(SLASHEQ, 2)), (PIPE, EQ) => return (1, Op::Composite(PIPEEQ, 2)), (AMP, EQ) => return (1, Op::Composite(AMPEQ, 2)), (CARET, EQ) => return (1, Op::Composite(CARETEQ, 2)), (PIPE, PIPE) => return (3, Op::Composite(PIPEPIPE, 2)), (AMP, AMP) => return (4, Op::Composite(AMPAMP, 2)), (L_ANGLE, EQ) => return (5, Op::Composite(LTEQ, 2)), (R_ANGLE, EQ) => return (5, Op::Composite(GTEQ, 2)), (L_ANGLE, L_ANGLE) => return (9, Op::Composite(SHL, 2)), (R_ANGLE, R_ANGLE) => return (9, Op::Composite(SHR, 2)), _ => (), } } let bp = match p.current() { EQ => 1, DOTDOT | DOTDOTEQ => 2, EQEQ | NEQ | L_ANGLE | R_ANGLE => 5, PIPE => 6, CARET => 7, AMP => 8, MINUS | PLUS => 10, STAR | SLASH | PERCENT => 11, _ => 0, }; (bp, Op::Simple) } // Parses expression with binding power of at least bp. fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) -> 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 BlockLike::Block; } lhs } None => return BlockLike::NotBlock, }; loop { let is_range = p.current() == DOTDOT || p.current() == DOTDOTEQ; let (op_bp, op) = current_op(p); if op_bp < bp { break; } let m = lhs.precede(p); match op { Op::Simple => p.bump(), Op::Composite(kind, n) => { p.bump_compound(kind, n); } } expr_bp(p, r, op_bp + 1); lhs = m.complete(p, if is_range { RANGE_EXPR } else { BIN_EXPR }); } BlockLike::NotBlock } const LHS_FIRST: TokenSet = atom::ATOM_EXPR_FIRST.union(token_set![AMP, STAR, EXCL, DOTDOT, DOTDOTEQ, 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(); // } AMP => { m = p.start(); p.bump(); p.eat(MUT_KW); REF_EXPR } // test unary_expr // fn foo() { // **&1; // !!true; // --1; // } STAR | EXCL | MINUS => { m = p.start(); p.bump(); PREFIX_EXPR } // test full_range_expr // fn foo() { xs[..]; } DOTDOT | DOTDOTEQ => { m = p.start(); p.bump(); if p.at_ts(EXPR_FIRST) { expr_bp(p, r, 2); } return Some((m.complete(p, RANGE_EXPR), BlockLike::NotBlock)); } _ => { let (lhs, blocklike) = atom::atom_expr(p, r)?; return Some(( postfix_expr(p, lhs, !(r.prefer_stmt && blocklike.is_block())), blocklike, )); } }; 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 allow_calls: bool, ) -> CompletedMarker { loop { lhs = match p.current() { // test stmt_postfix_expr_ambiguity // fn foo() { // match () { // _ => {} // () => {} // [] => {} // } // } L_PAREN if allow_calls => call_expr(p, lhs), L_BRACK if allow_calls => index_expr(p, lhs), DOT if p.nth(1) == IDENT && (p.nth(2) == L_PAREN || p.nth(2) == COLONCOLON) => { method_call_expr(p, lhs) } DOT => field_expr(p, lhs), // test postfix_range // fn foo() { let x = 1..; } DOTDOT | DOTDOTEQ if !EXPR_FIRST.contains(p.nth(1)) => { let m = lhs.precede(p); p.bump(); m.complete(p, RANGE_EXPR) } QUESTION => try_expr(p, lhs), AS_KW => cast_expr(p, lhs), _ => break, }; allow_calls = true } 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(L_PAREN)); 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(L_BRACK)); let m = lhs.precede(p); p.bump(); expr(p); p.expect(R_BRACK); 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(DOT) && p.nth(1) == IDENT && (p.nth(2) == L_PAREN || p.nth(2) == COLONCOLON)); let m = lhs.precede(p); p.bump(); name_ref(p); type_args::opt_type_arg_list(p, true); if p.at(L_PAREN) { arg_list(p); } m.complete(p, METHOD_CALL_EXPR) } // test field_expr // fn foo() { // x.foo; // x.0.bar; // } fn field_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker { assert!(p.at(DOT)); let m = lhs.precede(p); p.bump(); if p.at(IDENT) { name_ref(p) } else if p.at(INT_NUMBER) { p.bump() } 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(QUESTION)); let m = lhs.precede(p); p.bump(); m.complete(p, TRY_EXPR) } // test cast_expr // fn foo() { // 82 as i32; // 81 as i8 + 1; // 79 as i16 - 1; // } fn cast_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker { assert!(p.at(AS_KW)); let m = lhs.precede(p); p.bump(); // 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(L_PAREN)); let m = p.start(); p.bump(); while !p.at(R_PAREN) && !p.at(EOF) { if !p.at_ts(EXPR_FIRST) { p.error("expected expression"); break; } expr(p); if !p.at(R_PAREN) && !p.expect(COMMA) { break; } } p.eat(R_PAREN); 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) || p.at(L_ANGLE)); let m = p.start(); paths::expr_path(p); match p.current() { L_CURLY if !r.forbid_structs => { named_field_list(p); (m.complete(p, STRUCT_LIT), BlockLike::NotBlock) } EXCL => { let block_like = items::macro_call_after_excl(p); return (m.complete(p, MACRO_CALL), block_like); } _ => (m.complete(p, PATH_EXPR), BlockLike::NotBlock), } } // test struct_lit // fn foo() { // S {}; // S { x, y: 32, }; // S { x, y: 32, ..Default::default() }; // } pub(crate) fn named_field_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() { IDENT => { let m = p.start(); name_ref(p); if p.eat(COLON) { expr(p); } m.complete(p, NAMED_FIELD); } DOTDOT => { p.bump(); expr(p); } L_CURLY => error_block(p, "expected a field"), _ => p.err_and_bump("expected identifier"), } if !p.at(R_CURLY) { p.expect(COMMA); } } p.expect(R_CURLY); m.complete(p, NAMED_FIELD_LIST); }