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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 {
!matches!(
e.kind,
ast::ExprKind::If(..)
| ast::ExprKind::Match(..)
| ast::ExprKind::Block(..)
| ast::ExprKind::While(..)
| ast::ExprKind::Loop(..)
| ast::ExprKind::ForLoop(..)
| ast::ExprKind::TryBlock(..)
)
}
/// If an expression ends with `}`, returns the innermost expression ending in the `}`
pub fn expr_trailing_brace(mut expr: &ast::Expr) -> Option<&ast::Expr> {
use ast::ExprKind::*;
loop {
match &expr.kind {
AddrOf(_, _, e)
| Assign(_, e, _)
| AssignOp(_, _, e)
| Binary(_, _, e)
| Box(e)
| Break(_, Some(e))
| Closure(.., e, _)
| Let(_, e, _)
| Range(_, Some(e), _)
| Ret(Some(e))
| Unary(_, e)
| Yield(Some(e)) => {
expr = e;
}
Async(..) | Block(..) | ForLoop(..) | If(..) | Loop(..) | Match(..) | Struct(..)
| TryBlock(..) | While(..) => break Some(expr),
_ => break None,
}
}
}
|
