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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. | |
4 | // | |
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. | |
10 | ||
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11 | //! Routines the parser uses to classify AST nodes |
12 | ||
13 | // Predicates on exprs and stmts that the pretty-printer and parser use | |
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14 | |
15 | use ast; | |
223e47cc | 16 | |
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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 {...} | |
22 | /// |x| 5 | |
23 | /// isn't parsed as (if true {...} else {...} | x) | 5 | |
24 | pub fn expr_requires_semi_to_be_stmt(e: &ast::Expr) -> bool { | |
223e47cc | 25 | match e.node { |
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26 | ast::ExprIf(..) |
27 | | ast::ExprIfLet(..) | |
28 | | ast::ExprMatch(..) | |
29 | | ast::ExprBlock(_) | |
30 | | ast::ExprWhile(..) | |
31 | | ast::ExprWhileLet(..) | |
32 | | ast::ExprLoop(..) | |
33 | | ast::ExprForLoop(..) => false, | |
34 | _ => true | |
223e47cc LB |
35 | } |
36 | } | |
37 | ||
1a4d82fc | 38 | pub fn expr_is_simple_block(e: &ast::Expr) -> bool { |
223e47cc | 39 | match e.node { |
1a4d82fc JJ |
40 | ast::ExprBlock(ref block) => block.rules == ast::DefaultBlock, |
41 | _ => false | |
223e47cc LB |
42 | } |
43 | } | |
44 | ||
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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::Stmt_) -> bool { | |
49 | match *stmt { | |
50 | ast::StmtDecl(ref d, _) => { | |
223e47cc | 51 | match d.node { |
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52 | ast::DeclLocal(_) => true, |
53 | ast::DeclItem(_) => false | |
223e47cc LB |
54 | } |
55 | } | |
92a42be0 | 56 | ast::StmtExpr(ref e, _) => { expr_requires_semi_to_be_stmt(e) } |
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57 | ast::StmtSemi(..) => { false } |
58 | ast::StmtMac(..) => { false } | |
223e47cc LB |
59 | } |
60 | } |