src/libsyntax/parse/classify.rs


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//! Routines the parser uses to classify AST nodes

// Predicates on exprs and stmts that the pretty-printer and parser use

use crate::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::Match(..) |
        ast::ExprKind::Block(..) |
        ast::ExprKind::While(..) |
        ast::ExprKind::Loop(..) |
        ast::ExprKind::ForLoop(..) |
        ast::ExprKind::TryBlock(..) => false,
        _ => true,
    }
}