diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs index aa6614b0af4f7..d92eaee6f0c8e 100644 --- a/src/librustc/hir/lowering.rs +++ b/src/librustc/hir/lowering.rs @@ -84,6 +84,7 @@ pub struct LoweringContext<'a> { trait_impls: BTreeMap>, trait_default_impl: BTreeMap, + catch_scopes: Vec, loop_scopes: Vec, is_in_loop_condition: bool, @@ -123,6 +124,7 @@ pub fn lower_crate(sess: &Session, trait_impls: BTreeMap::new(), trait_default_impl: BTreeMap::new(), exported_macros: Vec::new(), + catch_scopes: Vec::new(), loop_scopes: Vec::new(), is_in_loop_condition: false, type_def_lifetime_params: DefIdMap(), @@ -261,6 +263,21 @@ impl<'a> LoweringContext<'a> { span } + fn with_catch_scope(&mut self, catch_id: NodeId, f: F) -> T + where F: FnOnce(&mut LoweringContext) -> T + { + let len = self.catch_scopes.len(); + self.catch_scopes.push(catch_id); + + let result = f(self); + assert_eq!(len + 1, self.catch_scopes.len(), + "catch scopes should be added and removed in stack order"); + + self.catch_scopes.pop().unwrap(); + + result + } + fn with_loop_scope(&mut self, loop_id: NodeId, f: F) -> T where F: FnOnce(&mut LoweringContext) -> T { @@ -295,15 +312,17 @@ impl<'a> LoweringContext<'a> { result } - fn with_new_loop_scopes(&mut self, f: F) -> T + fn with_new_scopes(&mut self, f: F) -> T where F: FnOnce(&mut LoweringContext) -> T { let was_in_loop_condition = self.is_in_loop_condition; self.is_in_loop_condition = false; + let catch_scopes = mem::replace(&mut self.catch_scopes, Vec::new()); let loop_scopes = mem::replace(&mut self.loop_scopes, Vec::new()); let result = f(self); - mem::replace(&mut self.loop_scopes, loop_scopes); + self.catch_scopes = catch_scopes; + self.loop_scopes = loop_scopes; self.is_in_loop_condition = was_in_loop_condition; @@ -1065,7 +1084,7 @@ impl<'a> LoweringContext<'a> { self.record_body(value, None)) } ItemKind::Fn(ref decl, unsafety, constness, abi, ref generics, ref body) => { - self.with_new_loop_scopes(|this| { + self.with_new_scopes(|this| { let body = this.lower_block(body); let body = this.expr_block(body, ThinVec::new()); let body_id = this.record_body(body, Some(decl)); @@ -1665,13 +1684,17 @@ impl<'a> LoweringContext<'a> { this.lower_opt_sp_ident(opt_ident), hir::LoopSource::Loop)) } + ExprKind::Catch(ref body) => { + // FIXME(cramertj): Add catch to HIR + self.with_catch_scope(e.id, |this| hir::ExprBlock(this.lower_block(body))) + } ExprKind::Match(ref expr, ref arms) => { hir::ExprMatch(P(self.lower_expr(expr)), arms.iter().map(|x| self.lower_arm(x)).collect(), hir::MatchSource::Normal) } ExprKind::Closure(capture_clause, ref decl, ref body, fn_decl_span) => { - self.with_new_loop_scopes(|this| { + self.with_new_scopes(|this| { this.with_parent_def(e.id, |this| { let expr = this.lower_expr(body); hir::ExprClosure(this.lower_capture_clause(capture_clause), @@ -2069,6 +2092,12 @@ impl<'a> LoweringContext<'a> { // Err(err) => #[allow(unreachable_code)] // return Carrier::from_error(From::from(err)), // } + + // FIXME(cramertj): implement breaking to catch + if !self.catch_scopes.is_empty() { + bug!("`?` in catch scopes is unimplemented") + } + let unstable_span = self.allow_internal_unstable("?", e.span); // Carrier::translate() diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs index fa320d2ca8b6c..a456fa512254c 100644 --- a/src/libsyntax/ast.rs +++ b/src/libsyntax/ast.rs @@ -935,6 +935,8 @@ pub enum ExprKind { Closure(CaptureBy, P, P, Span), /// A block (`{ ... }`) Block(P), + /// A catch block (`catch { ... }`) + Catch(P), /// An assignment (`a = foo()`) Assign(P, P), diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs index e7bf16eae9ee6..15913d56d162f 100644 --- a/src/libsyntax/feature_gate.rs +++ b/src/libsyntax/feature_gate.rs @@ -339,6 +339,9 @@ declare_features! ( // `extern "x86-interrupt" fn()` (active, abi_x86_interrupt, "1.17.0", Some(40180)), + + // Allows the `catch {...}` expression + (active, catch_expr, "1.17.0", Some(31436)), ); declare_features! ( @@ -1287,6 +1290,9 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> { } } } + ast::ExprKind::Catch(_) => { + gate_feature_post!(&self, catch_expr, e.span, "`catch` expression is experimental"); + } _ => {} } visit::walk_expr(self, e); diff --git a/src/libsyntax/fold.rs b/src/libsyntax/fold.rs index aa968f03d6887..9f11d0173d6d5 100644 --- a/src/libsyntax/fold.rs +++ b/src/libsyntax/fold.rs @@ -1269,6 +1269,7 @@ pub fn noop_fold_expr(Expr {id, node, span, attrs}: Expr, folder: &mu }; } ExprKind::Try(ex) => ExprKind::Try(folder.fold_expr(ex)), + ExprKind::Catch(body) => ExprKind::Catch(folder.fold_block(body)), }, id: folder.new_id(id), span: folder.new_span(span), diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs index ff7918cc2783a..8f66c1a2b8cf6 100644 --- a/src/libsyntax/parse/parser.rs +++ b/src/libsyntax/parse/parser.rs @@ -2280,6 +2280,12 @@ impl<'a> Parser<'a> { BlockCheckMode::Unsafe(ast::UserProvided), attrs); } + if self.is_catch_expr() { + assert!(self.eat_keyword(keywords::Do)); + assert!(self.eat_keyword(keywords::Catch)); + let lo = self.prev_span.lo; + return self.parse_catch_expr(lo, attrs); + } if self.eat_keyword(keywords::Return) { if self.token.can_begin_expr() { let e = self.parse_expr()?; @@ -3099,6 +3105,16 @@ impl<'a> Parser<'a> { Ok(self.mk_expr(span_lo, hi, ExprKind::Loop(body, opt_ident), attrs)) } + /// Parse a `do catch {...}` expression (`do catch` token already eaten) + pub fn parse_catch_expr(&mut self, span_lo: BytePos, mut attrs: ThinVec) + -> PResult<'a, P> + { + let (iattrs, body) = self.parse_inner_attrs_and_block()?; + attrs.extend(iattrs); + let hi = body.span.hi; + Ok(self.mk_expr(span_lo, hi, ExprKind::Catch(body), attrs)) + } + // `match` token already eaten fn parse_match_expr(&mut self, mut attrs: ThinVec) -> PResult<'a, P> { let match_span = self.prev_span; @@ -3706,6 +3722,15 @@ impl<'a> Parser<'a> { }) } + fn is_catch_expr(&mut self) -> bool { + self.token.is_keyword(keywords::Do) && + self.look_ahead(1, |t| t.is_keyword(keywords::Catch)) && + self.look_ahead(2, |t| *t == token::OpenDelim(token::Brace)) && + + // prevent `while catch {} {}`, `if catch {} {} else {}`, etc. + !self.restrictions.contains(Restrictions::RESTRICTION_NO_STRUCT_LITERAL) + } + fn is_union_item(&self) -> bool { self.token.is_keyword(keywords::Union) && self.look_ahead(1, |t| t.is_ident() && !t.is_any_keyword()) @@ -4882,6 +4907,7 @@ impl<'a> Parser<'a> { /// Parse struct Foo { ... } fn parse_item_struct(&mut self) -> PResult<'a, ItemInfo> { let class_name = self.parse_ident()?; + let mut generics = self.parse_generics()?; // There is a special case worth noting here, as reported in issue #17904. @@ -4931,6 +4957,7 @@ impl<'a> Parser<'a> { /// Parse union Foo { ... } fn parse_item_union(&mut self) -> PResult<'a, ItemInfo> { let class_name = self.parse_ident()?; + let mut generics = self.parse_generics()?; let vdata = if self.token.is_keyword(keywords::Where) { diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs index 5b65aac92b81c..25601f2420e8a 100644 --- a/src/libsyntax/parse/token.rs +++ b/src/libsyntax/parse/token.rs @@ -86,6 +86,7 @@ fn ident_can_begin_expr(ident: ast::Ident) -> bool { !ident_token.is_any_keyword() || ident_token.is_path_segment_keyword() || [ + keywords::Do.name(), keywords::Box.name(), keywords::Break.name(), keywords::Continue.name(), diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs index 3efadbd00d1e0..83753f398a376 100644 --- a/src/libsyntax/print/pprust.rs +++ b/src/libsyntax/print/pprust.rs @@ -2279,6 +2279,11 @@ impl<'a> State<'a> { self.print_expr(e)?; word(&mut self.s, "?")? } + ast::ExprKind::Catch(ref blk) => { + self.head("do catch")?; + space(&mut self.s)?; + self.print_block_with_attrs(&blk, attrs)? + } } self.ann.post(self, NodeExpr(expr))?; self.end() diff --git a/src/libsyntax/symbol.rs b/src/libsyntax/symbol.rs index c278171aa109a..6642c60d256b3 100644 --- a/src/libsyntax/symbol.rs +++ b/src/libsyntax/symbol.rs @@ -221,9 +221,10 @@ declare_keywords! { (53, Default, "default") (54, StaticLifetime, "'static") (55, Union, "union") + (56, Catch, "catch") // A virtual keyword that resolves to the crate root when used in a lexical scope. - (56, CrateRoot, "{{root}}") + (57, CrateRoot, "{{root}}") } // If an interner exists in TLS, return it. Otherwise, prepare a fresh one. diff --git a/src/libsyntax/visit.rs b/src/libsyntax/visit.rs index ee7dd18247b21..a5333f3bb6a6e 100644 --- a/src/libsyntax/visit.rs +++ b/src/libsyntax/visit.rs @@ -779,6 +779,9 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) { ExprKind::Try(ref subexpression) => { visitor.visit_expr(subexpression) } + ExprKind::Catch(ref body) => { + visitor.visit_block(body) + } } visitor.visit_expr_post(expression) diff --git a/src/test/compile-fail/catch-in-match.rs b/src/test/compile-fail/catch-in-match.rs new file mode 100644 index 0000000000000..9f9968e81242a --- /dev/null +++ b/src/test/compile-fail/catch-in-match.rs @@ -0,0 +1,15 @@ +// Copyright 2017 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#![feature(catch_expr)] + +fn main() { + match do catch { false } { _ => {} } //~ ERROR expected expression, found reserved keyword `do` +} diff --git a/src/test/compile-fail/catch-in-while.rs b/src/test/compile-fail/catch-in-while.rs new file mode 100644 index 0000000000000..cb8613ee60b42 --- /dev/null +++ b/src/test/compile-fail/catch-in-while.rs @@ -0,0 +1,15 @@ +// Copyright 2017 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#![feature(catch_expr)] + +fn main() { + while do catch { false } {} //~ ERROR expected expression, found reserved keyword `do` +} diff --git a/src/test/compile-fail/feature-gate-catch_expr.rs b/src/test/compile-fail/feature-gate-catch_expr.rs new file mode 100644 index 0000000000000..5568a5cf0aac2 --- /dev/null +++ b/src/test/compile-fail/feature-gate-catch_expr.rs @@ -0,0 +1,17 @@ +// Copyright 2017 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +pub fn main() { + let catch_result = do catch { //~ ERROR `catch` expression is experimental + let x = 5; + x + }; + assert_eq!(catch_result, 5); +} diff --git a/src/test/run-pass/catch-expr.rs b/src/test/run-pass/catch-expr.rs new file mode 100644 index 0000000000000..a9b28a534a348 --- /dev/null +++ b/src/test/run-pass/catch-expr.rs @@ -0,0 +1,32 @@ +// Copyright 2017 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#![feature(catch_expr)] + +struct catch {} + +pub fn main() { + let catch_result = do catch { + let x = 5; + x + }; + assert_eq!(catch_result, 5); + + let mut catch = true; + while catch { catch = false; } + assert_eq!(catch, false); + + catch = if catch { false } else { true }; + assert_eq!(catch, true); + + match catch { + _ => {} + }; +}