1 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Routines the parser uses to classify AST nodes
13 // Predicates on exprs and stmts that the pretty-printer and parser use
15 use ast::{self, BlockCheckMode};
17 /// Does this expression require a semicolon to be treated
18 /// as a statement? The negation of this: 'can this expression
19 /// be used as a statement without a semicolon' -- is used
20 /// as an early-bail-out in the parser so that, for instance,
21 /// if true {...} else {...}
23 /// isn't parsed as (if true {...} else {...} | x) | 5
24 pub fn expr_requires_semi_to_be_stmt(e: &ast::Expr) -> bool {
26 ast::ExprKind::If(..) |
27 ast::ExprKind::IfLet(..) |
28 ast::ExprKind::Match(..) |
29 ast::ExprKind::Block(_) |
30 ast::ExprKind::While(..) |
31 ast::ExprKind::WhileLet(..) |
32 ast::ExprKind::Loop(..) |
33 ast::ExprKind::ForLoop(..) => false,
38 pub fn expr_is_simple_block(e: &ast::Expr) -> bool {
40 ast::ExprKind::Block(ref block) => block.rules == BlockCheckMode::Default,
45 /// this statement requires a semicolon after it.
46 /// note that in one case (`stmt_semi`), we've already
47 /// seen the semicolon, and thus don't need another.
48 pub fn stmt_ends_with_semi(stmt: &ast::StmtKind) -> bool {
50 ast::StmtKind::Local(_) => true,
51 ast::StmtKind::Expr(ref e) => expr_requires_semi_to_be_stmt(e),
52 ast::StmtKind::Item(_) |
53 ast::StmtKind::Semi(..) |
54 ast::StmtKind::Mac(..) => false,