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// Copyright 2012 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 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. //! Routines the parser uses to classify AST nodes // Predicates on exprs and stmts that the pretty-printer and parser use use ast; /// Does this expression require a semicolon to be treated /// as a statement? The negation of this: 'can this expression /// be used as a statement without a semicolon' -- is used /// as an early-bail-out in the parser so that, for instance, /// if true {...} else {...} /// |x| 5 /// isn't parsed as (if true {...} else {...} | x) | 5 pub fn expr_requires_semi_to_be_stmt(e: &ast::Expr) -> bool { match e.node { ast::ExprKind::If(..) | ast::ExprKind::IfLet(..) | ast::ExprKind::Match(..) | ast::ExprKind::Block(..) | ast::ExprKind::While(..) | ast::ExprKind::WhileLet(..) | ast::ExprKind::Loop(..) | ast::ExprKind::ForLoop(..) | ast::ExprKind::Catch(..) => false, _ => true, } } /// this statement requires a semicolon after it. /// note that in one case (`stmt_semi`), we've already /// seen the semicolon, and thus don't need another. pub fn stmt_ends_with_semi(stmt: &ast::StmtKind) -> bool { match *stmt { ast::StmtKind::Local(_) => true, ast::StmtKind::Expr(ref e) => expr_requires_semi_to_be_stmt(e), ast::StmtKind::Item(_) | ast::StmtKind::Semi(..) | ast::StmtKind::Mac(..) => false, } }