bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

Make offset_of field parsing use metavariable which handles any spacing

Browse source
This commit is contained in:
George Bateman 2024-01-02 22:12:35 +00:00
parent e51e98dde6
commit 09bb07e38f
No known key found for this signature in database
GPG key ID: C417AA9C4039EFCF
13 changed files with 294 additions and 264 deletions
Download patch file Download diff file Expand all files Collapse all files

164
compiler/rustc_parse/src/parser/expr.rs
View file

@ -1023,7 +1023,7 @@ impl<'a> Parser<'a> {
// we should break everything including floats into more basic proc-macro style
// tokens in the lexer (probably preferable).
// See also `TokenKind::break_two_token_op` which does similar splitting of `>>` into `>`.
fn break_up_float(&mut self, float: Symbol) -> DestructuredFloat {
fn break_up_float(&self, float: Symbol, span: Span) -> DestructuredFloat {
#[derive(Debug)]
enum FloatComponent {
IdentLike(String),
@ -1053,7 +1053,6 @@ impl<'a> Parser<'a> {
// With proc macros the span can refer to anything, the source may be too short,
// or too long, or non-ASCII. It only makes sense to break our span into components
// if its underlying text is identical to our float literal.
let span = self.token.span;
let can_take_span_apart =
|| self.span_to_snippet(span).as_deref() == Ok(float_str).as_deref();
@ -1115,7 +1114,7 @@ impl<'a> Parser<'a> {
float: Symbol,
suffix: Option<Symbol>,
) -> P<Expr> {
match self.break_up_float(float) {
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)
@ -1143,40 +1142,105 @@ impl<'a> Parser<'a> {
}
}
fn parse_field_name_maybe_tuple(&mut self) -> PResult<'a, ThinVec<Ident>> {
let token::Literal(token::Lit { kind: token::Float, symbol, suffix }) = self.token.kind
else {
return Ok(thin_vec![self.parse_field_name()?]);
};
Ok(match self.break_up_float(symbol) {
// 1e2
DestructuredFloat::Single(sym, sp) => {
self.bump();
thin_vec![Ident::new(sym, sp)]
/// 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.
fn parse_floating_field_access(&mut self) -> PResult<'a, P<[Ident]>> {
let mut fields = Vec::new();
let mut trailing_dot = None;
loop {
// This is expected to use a metavariable $(args:expr)+, but the builtin syntax
// could be called directly. Calling `parse_expr` allows this function to only
// consider `Expr`s.
let expr = self.parse_expr()?;
let mut current = &expr;
let start_idx = fields.len();
loop {
match current.kind {
ExprKind::Field(ref left, right) => {
// Field access is read right-to-left.
fields.insert(start_idx, right);
trailing_dot = None;
current = left;
}
// Parse this both to give helpful error messages and to
// verify it can be done with this parser setup.
ExprKind::Index(ref left, ref _right, span) => {
self.sess.emit_err(errors::ArrayIndexInOffsetOf(span));
current = left;
}
ExprKind::Lit(token::Lit {
kind: token::Float | token::Integer,
symbol,
suffix,
}) => {
if let Some(suffix) = suffix {
self.expect_no_tuple_index_suffix(current.span, suffix);
}
match self.break_up_float(symbol, current.span) {
// 1e2
DestructuredFloat::Single(sym, sp) => {
trailing_dot = None;
fields.insert(start_idx, Ident::new(sym, sp));
}
// 1.
DestructuredFloat::TrailingDot(sym, sym_span, dot_span) => {
assert!(suffix.is_none());
trailing_dot = Some(dot_span);
fields.insert(start_idx, Ident::new(sym, sym_span));
}
// 1.2 | 1.2e3
DestructuredFloat::MiddleDot(
symbol1,
span1,
_dot_span,
symbol2,
span2,
) => {
trailing_dot = None;
fields.insert(start_idx, Ident::new(symbol2, span2));
fields.insert(start_idx, Ident::new(symbol1, span1));
}
DestructuredFloat::Error => {
trailing_dot = None;
fields.insert(start_idx, Ident::new(symbol, self.prev_token.span));
}
}
break;
}
ExprKind::Path(None, Path { ref segments, .. }) => {
match &segments[..] {
[PathSegment { ident, args: None, .. }] => {
trailing_dot = None;
fields.insert(start_idx, *ident)
}
_ => {
self.sess.emit_err(errors::InvalidOffsetOf(current.span));
break;
}
}
break;
}
_ => {
self.sess.emit_err(errors::InvalidOffsetOf(current.span));
break;
}
}
}
// 1.
DestructuredFloat::TrailingDot(sym, sym_span, dot_span) => {
assert!(suffix.is_none());
// Analogous to `Self::break_and_eat`
self.break_last_token = true;
// This might work, in cases like `1. 2`, and might not,
// in cases like `offset_of!(Ty, 1.)`. It depends on what comes
// after the float-like token, and therefore we have to make
// the other parts of the parser think that there is a dot literal.
self.token = Token::new(token::Ident(sym, false), sym_span);
self.bump_with((Token::new(token::Dot, dot_span), self.token_spacing));
thin_vec![Ident::new(sym, sym_span)]
if matches!(self.token.kind, token::CloseDelim(..) | token::Comma) {
break;
} else if trailing_dot.is_none() {
// This loop should only repeat if there is a trailing dot.
self.sess.emit_err(errors::InvalidOffsetOf(self.token.span));
break;
}
// 1.2 | 1.2e3
DestructuredFloat::MiddleDot(symbol1, ident1_span, _dot_span, symbol2, ident2_span) => {
self.bump();
thin_vec![Ident::new(symbol1, ident1_span), Ident::new(symbol2, ident2_span)]
}
DestructuredFloat::Error => {
self.bump();
thin_vec![Ident::new(symbol, self.prev_token.span)]
}
})
}
if let Some(dot) = trailing_dot {
self.sess.emit_err(errors::InvalidOffsetOf(dot));
}
Ok(fields.into_iter().collect())
}
fn parse_expr_tuple_field_access(
@ -1907,15 +1971,29 @@ impl<'a> Parser<'a> {
let container = self.parse_ty()?;
self.expect(&TokenKind::Comma)?;
let seq_sep = SeqSep { sep: Some(token::Dot), trailing_sep_allowed: false };
let (fields, _trailing, _recovered) = self.parse_seq_to_before_end(
&TokenKind::CloseDelim(Delimiter::Parenthesis),
seq_sep,
Parser::parse_field_name_maybe_tuple,
)?;
let fields = fields.into_iter().flatten().collect::<Vec<_>>();
let fields = self.parse_floating_field_access()?;
let trailing_comma = self.eat_noexpect(&TokenKind::Comma);
if let Err(mut e) =
self.expect_one_of(&[], &[TokenKind::CloseDelim(Delimiter::Parenthesis)])
{
if trailing_comma {
e.note("unexpected third argument to offset_of");
} else {
e.note("offset_of expects dot-separated field and variant names");
}
e.emit();
}
// Eat tokens until the macro call ends.
if self.may_recover() {
while !matches!(self.token.kind, token::CloseDelim(..) | token::Eof) {
self.bump();
}
}
let span = lo.to(self.token.span);
Ok(self.mk_expr(span, ExprKind::OffsetOf(container, fields.into())))
Ok(self.mk_expr(span, ExprKind::OffsetOf(container, fields)))
}
/// Returns a string literal if the next token is a string literal.