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Rollup merge of #122858 - nnethercote:tweak-parse_dot_suffix_expr, r=est31

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Tweak `parse_dot_suffix_expr`

I find this function hard to understand, so I rewrote it.

r? ```@est31```
This commit is contained in:
Matthias Krüger 2024-03-25 11:00:12 +01:00 committed by GitHub
commit 4cae68b0cf
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1 changed files with 50 additions and 48 deletions
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98
compiler/rustc_parse/src/parser/expr.rs
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@ -16,7 +16,6 @@ use core::mem;
use core::ops::ControlFlow;
use rustc_ast::ptr::P;
use rustc_ast::token::{self, Delimiter, Token, TokenKind};
use rustc_ast::tokenstream::Spacing;
use rustc_ast::util::case::Case;
use rustc_ast::util::classify;
use rustc_ast::util::parser::{prec_let_scrutinee_needs_par, AssocOp, Fixity};
@ -999,13 +998,57 @@ impl<'a> Parser<'a> {
}
pub fn parse_dot_suffix_expr(&mut self, lo: Span, base: P<Expr>) -> PResult<'a, P<Expr>> {
// At this point we've consumed something like `expr.` and `self.token` holds the token
// after the dot.
match self.token.uninterpolate().kind {
token::Ident(..) => self.parse_dot_suffix(base, lo),
token::Literal(token::Lit { kind: token::Integer, symbol, suffix }) => {
Ok(self.parse_expr_tuple_field_access(lo, base, symbol, suffix, None))
let ident_span = self.token.span;
self.bump();
Ok(self.mk_expr_tuple_field_access(lo, ident_span, base, symbol, suffix))
}
token::Literal(token::Lit { kind: token::Float, symbol, suffix }) => {
Ok(self.parse_expr_tuple_field_access_float(lo, base, symbol, suffix))
Ok(match self.break_up_float(symbol, self.token.span) {
// 1e2
DestructuredFloat::Single(sym, _sp) => {
// `foo.1e2`: a single complete dot access, fully consumed. We end up with
// the `1e2` token in `self.prev_token` and the following token in
// `self.token`.
let ident_span = self.token.span;
self.bump();
self.mk_expr_tuple_field_access(lo, ident_span, base, sym, suffix)
}
// 1.
DestructuredFloat::TrailingDot(sym, ident_span, dot_span) => {
// `foo.1.`: a single complete dot access and the start of another.
// We end up with the `sym` (`1`) token in `self.prev_token` and a dot in
// `self.token`.
assert!(suffix.is_none());
self.token = Token::new(token::Ident(sym, IdentIsRaw::No), ident_span);
self.bump_with((Token::new(token::Dot, dot_span), self.token_spacing));
self.mk_expr_tuple_field_access(lo, ident_span, base, sym, None)
}
// 1.2 | 1.2e3
DestructuredFloat::MiddleDot(
sym1,
ident1_span,
_dot_span,
sym2,
ident2_span,
) => {
// `foo.1.2` (or `foo.1.2e3`): two complete dot accesses. We end up with
// the `sym2` (`2` or `2e3`) token in `self.prev_token` and the following
// token in `self.token`.
let next_token2 =
Token::new(token::Ident(sym2, IdentIsRaw::No), ident2_span);
self.bump_with((next_token2, self.token_spacing));
self.bump();
let base1 =
self.mk_expr_tuple_field_access(lo, ident1_span, base, sym1, None);
self.mk_expr_tuple_field_access(lo, ident2_span, base1, sym2, suffix)
}
DestructuredFloat::Error => base,
})
}
_ => {
self.error_unexpected_after_dot();
@ -1119,41 +1162,6 @@ impl<'a> Parser<'a> {
}
}
fn parse_expr_tuple_field_access_float(
&mut self,
lo: Span,
base: P<Expr>,
float: Symbol,
suffix: Option<Symbol>,
) -> P<Expr> {
match self.break_up_float(float, self.token.span) {
// 1e2
DestructuredFloat::Single(sym, _sp) => {
self.parse_expr_tuple_field_access(lo, base, sym, suffix, None)
}
// 1.
DestructuredFloat::TrailingDot(sym, ident_span, dot_span) => {
assert!(suffix.is_none());
self.token = Token::new(token::Ident(sym, IdentIsRaw::No), ident_span);
let next_token = (Token::new(token::Dot, dot_span), self.token_spacing);
self.parse_expr_tuple_field_access(lo, base, sym, None, Some(next_token))
}
// 1.2 | 1.2e3
DestructuredFloat::MiddleDot(symbol1, ident1_span, dot_span, symbol2, ident2_span) => {
self.token = Token::new(token::Ident(symbol1, IdentIsRaw::No), ident1_span);
// This needs to be `Spacing::Alone` to prevent regressions.
// See issue #76399 and PR #76285 for more details
let next_token1 = (Token::new(token::Dot, dot_span), Spacing::Alone);
let base1 =
self.parse_expr_tuple_field_access(lo, base, symbol1, None, Some(next_token1));
let next_token2 = Token::new(token::Ident(symbol2, IdentIsRaw::No), ident2_span);
self.bump_with((next_token2, self.token_spacing)); // `.`
self.parse_expr_tuple_field_access(lo, base1, symbol2, suffix, None)
}
DestructuredFloat::Error => base,
}
}
/// Parse the field access used in offset_of, matched by `$(e:expr)+`.
/// Currently returns a list of idents. However, it should be possible in
/// future to also do array indices, which might be arbitrary expressions.
@ -1255,24 +1263,18 @@ impl<'a> Parser<'a> {
Ok(fields.into_iter().collect())
}
fn parse_expr_tuple_field_access(
fn mk_expr_tuple_field_access(
&mut self,
lo: Span,
ident_span: Span,
base: P<Expr>,
field: Symbol,
suffix: Option<Symbol>,
next_token: Option<(Token, Spacing)>,
) -> P<Expr> {
match next_token {
Some(next_token) => self.bump_with(next_token),
None => self.bump(),
}
let span = self.prev_token.span;
let field = ExprKind::Field(base, Ident::new(field, span));
if let Some(suffix) = suffix {
self.expect_no_tuple_index_suffix(span, suffix);
self.expect_no_tuple_index_suffix(ident_span, suffix);
}
self.mk_expr(lo.to(span), field)
self.mk_expr(lo.to(ident_span), ExprKind::Field(base, Ident::new(field, ident_span)))
}
/// Parse a function call expression, `expr(...)`.