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
expr_requires_semi_to_be_stmt(e: &ast::Expr) -> bool14 pub fn expr_requires_semi_to_be_stmt(e: &ast::Expr) -> bool {
15 !matches!(
16 e.kind,
17 ast::ExprKind::If(..)
18 | ast::ExprKind::Match(..)
19 | ast::ExprKind::Block(..)
20 | ast::ExprKind::While(..)
21 | ast::ExprKind::Loop(..)
22 | ast::ExprKind::ForLoop(..)
23 | ast::ExprKind::TryBlock(..)
24 | ast::ExprKind::ConstBlock(..)
25 )
26 }
27
28 /// If an expression ends with `}`, returns the innermost expression ending in the `}`
expr_trailing_brace(mut expr: &ast::Expr) -> Option<&ast::Expr>29 pub fn expr_trailing_brace(mut expr: &ast::Expr) -> Option<&ast::Expr> {
30 use ast::ExprKind::*;
31
32 loop {
33 match &expr.kind {
34 AddrOf(_, _, e)
35 | Assign(_, e, _)
36 | AssignOp(_, _, e)
37 | Binary(_, _, e)
38 | Break(_, Some(e))
39 | Let(_, e, _)
40 | Range(_, Some(e), _)
41 | Ret(Some(e))
42 | Unary(_, e)
43 | Yield(Some(e)) => {
44 expr = e;
45 }
46 Closure(closure) => {
47 expr = &closure.body;
48 }
49 Async(..) | Block(..) | ForLoop(..) | If(..) | Loop(..) | Match(..) | Struct(..)
50 | TryBlock(..) | While(..) => break Some(expr),
51 _ => break None,
52 }
53 }
54 }
55