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Eliminate precedence arithmetic from rustc_ast_pretty

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David Tolnay 2024-11-28 13:44:46 -08:00
parent 7442931d49
commit c02032cd6a
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1 changed files with 15 additions and 24 deletions
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39
compiler/rustc_ast_pretty/src/pprust/state/expr.rs
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@ -276,21 +276,22 @@ impl<'a> State<'a> {
fixup: FixupContext,
) {
let assoc_op = AssocOp::from_ast_binop(op.node);
let prec = assoc_op.precedence() as i8;
let fixity = assoc_op.fixity();
let binop_prec = assoc_op.precedence() as i8;
let left_prec = lhs.precedence();
let right_prec = rhs.precedence();
let (left_prec, right_prec) = match fixity {
Fixity::Left => (prec, prec + 1),
Fixity::Right => (prec + 1, prec),
Fixity::None => (prec + 1, prec + 1),
let (mut left_needs_paren, right_needs_paren) = match assoc_op.fixity() {
Fixity::Left => (left_prec < binop_prec, right_prec <= binop_prec),
Fixity::Right => (left_prec <= binop_prec, right_prec < binop_prec),
Fixity::None => (left_prec <= binop_prec, right_prec <= binop_prec),
};
let left_prec = match (&lhs.kind, op.node) {
match (&lhs.kind, op.node) {
// These cases need parens: `x as i32 < y` has the parser thinking that `i32 < y` is
// the beginning of a path type. It starts trying to parse `x as (i32 < y ...` instead
// of `(x as i32) < ...`. We need to convince it _not_ to do that.
(&ast::ExprKind::Cast { .. }, ast::BinOpKind::Lt | ast::BinOpKind::Shl) => {
parser::PREC_FORCE_PAREN
left_needs_paren = true;
}
// We are given `(let _ = a) OP b`.
//
@ -300,26 +301,16 @@ impl<'a> State<'a> {
// - Otherwise, e.g. when we have `(let a = b) < c` in AST,
// parens are required since the parser would interpret `let a = b < c` as
// `let a = (b < c)`. To achieve this, we force parens.
(&ast::ExprKind::Let { .. }, _) if !parser::needs_par_as_let_scrutinee(prec) => {
parser::PREC_FORCE_PAREN
(&ast::ExprKind::Let { .. }, _) if !parser::needs_par_as_let_scrutinee(binop_prec) => {
left_needs_paren = true;
}
_ => left_prec,
};
self.print_expr_cond_paren(
lhs,
lhs.precedence() < left_prec,
fixup.leftmost_subexpression(),
);
_ => {}
}
self.print_expr_cond_paren(lhs, left_needs_paren, fixup.leftmost_subexpression());
self.space();
self.word_space(op.node.as_str());
self.print_expr_cond_paren(
rhs,
rhs.precedence() < right_prec,
fixup.subsequent_subexpression(),
);
self.print_expr_cond_paren(rhs, right_needs_paren, fixup.subsequent_subexpression());
}
fn print_expr_unary(&mut self, op: ast::UnOp, expr: &ast::Expr, fixup: FixupContext) {