compiler/rustc_ast/src/util/classify.rs

   1 //! Routines the parser uses to classify AST nodes
   2
   3 // Predicates on exprs and stmts that the pretty-printer and parser use
   4
   5 use crate::ast;
   6
   7 /// Does this expression require a semicolon to be treated
   8 /// as a statement? The negation of this: 'can this expression
   9 /// be used as a statement without a semicolon' -- is used
  10 /// as an early-bail-out in the parser so that, for instance,
  11 ///     if true {...} else {...}
  12 ///      |x| 5
  13 /// isn't parsed as (if true {...} else {...} | x) | 5
  14 pub fn expr_requires_semi_to_be_stmt(e: &ast::Expr) -> bool {
  15     match e.kind {
  16         ast::ExprKind::If(..)
  17         | ast::ExprKind::Match(..)
  18         | ast::ExprKind::Block(..)
  19         | ast::ExprKind::While(..)
  20         | ast::ExprKind::Loop(..)
  21         | ast::ExprKind::ForLoop(..)
  22         | ast::ExprKind::TryBlock(..) => false,
  23         _ => true,
  24     }
  25 }