parser/grammar/patterns.rs
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use super::*;
pub(super) const PATTERN_FIRST: TokenSet =
expressions::LITERAL_FIRST.union(paths::PATH_FIRST).union(TokenSet::new(&[
T![box],
T![ref],
T![mut],
T![const],
T!['('],
T!['['],
T![&],
T![_],
T![-],
T![.],
]));
const PAT_TOP_FIRST: TokenSet = PATTERN_FIRST.union(TokenSet::new(&[T![|]]));
/// Set of possible tokens at the start of a range pattern's end bound.
const RANGE_PAT_END_FIRST: TokenSet =
expressions::LITERAL_FIRST.union(paths::PATH_FIRST).union(TokenSet::new(&[T![-], T![const]]));
/// Parses a pattern list separated by pipes `|`.
pub(crate) fn pattern(p: &mut Parser<'_>) {
pattern_r(p, PAT_RECOVERY_SET);
}
pub(crate) fn pattern_single(p: &mut Parser<'_>) {
pattern_single_r(p, PAT_RECOVERY_SET);
}
/// Parses a pattern list separated by pipes `|`
/// using the given `recovery_set`.
pub(super) fn pattern_top_r(p: &mut Parser<'_>, recovery_set: TokenSet) {
pattern_r(p, recovery_set);
}
// test or_pattern
// fn main() {
// match () {
// (_ | _) => (),
// &(_ | _) => (),
// (_ | _,) => (),
// [_ | _,] => (),
// }
// }
/// Parses a pattern list separated by pipes `|`, with no leading `|`,using the
/// given `recovery_set`.
fn pattern_r(p: &mut Parser<'_>, recovery_set: TokenSet) {
let m = p.start();
let has_leading_pipe = p.eat(T![|]);
pattern_single_r(p, recovery_set);
if !p.at(T![|]) && !has_leading_pipe {
m.abandon(p);
return;
}
while p.eat(T![|]) {
pattern_single_r(p, recovery_set);
}
m.complete(p, OR_PAT);
}
fn pattern_single_r(p: &mut Parser<'_>, recovery_set: TokenSet) {
// test range_pat
// fn main() {
// match 92 {
// 0 ... 100 => (),
// 101 ..= 200 => (),
// 200 .. 301 => (),
// 302 .. => (),
// ..= 303 => (),
// }
//
// match Some(10 as u8) {
// Some(0) | None => (),
// Some(1..) => (),
// Some(..=2) => (),
// }
//
// match () {
// S { a: 0 } => (),
// S { a: 1.. } => (),
// S { a: ..=2 } => (),
// }
//
// match () {
// [0] => (),
// [1..] => (),
// [..=2] => (),
// }
//
// match (10 as u8, 5 as u8) {
// (0, _) => (),
// (1.., _) => (),
// (..=2, _) => (),
// }
// }
if p.at(T![..=]) {
let m = p.start();
p.bump(T![..=]);
atom_pat(p, recovery_set);
m.complete(p, RANGE_PAT);
return;
}
// test exclusive_range_pat
// fn main() {
// match 42 {
// ..0 => {}
// 1..2 => {}
// }
// }
// test dot_dot_pat
// fn main() {
// let .. = ();
// //
// // Tuples
// //
// let (a, ..) = ();
// let (a, ..,) = ();
// let Tuple(a, ..) = ();
// let Tuple(a, ..,) = ();
// let (.., ..) = ();
// let Tuple(.., ..) = ();
// let (.., a, ..) = ();
// let Tuple(.., a, ..) = ();
// //
// // Slices
// //
// let [..] = ();
// let [head, ..] = ();
// let [head, tail @ ..] = ();
// let [head, .., cons] = ();
// let [head, mid @ .., cons] = ();
// let [head, .., .., cons] = ();
// let [head, .., mid, tail @ ..] = ();
// let [head, .., mid, .., cons] = ();
// }
if p.at(T![..]) {
let m = p.start();
p.bump(T![..]);
if p.at_ts(RANGE_PAT_END_FIRST) {
atom_pat(p, recovery_set);
m.complete(p, RANGE_PAT);
} else {
m.complete(p, REST_PAT);
}
return;
}
if let Some(lhs) = atom_pat(p, recovery_set) {
for range_op in [T![...], T![..=], T![..]] {
if p.at(range_op) {
let m = lhs.precede(p);
p.bump(range_op);
// testing if we're at one of the following positions:
// `0 .. =>`
// ^
// `let 0 .. =`
// ^
// `let 0..: _ =`
// ^
// (1.., _)
// ^
// `Some(0 .. )`
// ^
// `S { t: 0.. }`
// ^
// `[0..]`
// ^
// `0 .. if`
// ^
if matches!(
p.current(),
T![=] | T![,] | T![:] | T![')'] | T!['}'] | T![']'] | T![if] | EOF
) {
// test half_open_range_pat
// fn f() {
// let 0 .. = 1u32;
// let 0..: _ = 1u32;
//
// match 42 {
// 0 .. if true => (),
// _ => (),
// }
// }
} else {
atom_pat(p, recovery_set);
}
m.complete(p, RANGE_PAT);
return;
}
}
}
}
const PAT_RECOVERY_SET: TokenSet =
TokenSet::new(&[T![let], T![if], T![while], T![loop], T![match], T![')'], T![,], T![=]]);
fn atom_pat(p: &mut Parser<'_>, recovery_set: TokenSet) -> Option<CompletedMarker> {
let m = match p.current() {
T![box] => box_pat(p),
T![ref] | T![mut] => ident_pat(p, true),
T![const] => const_block_pat(p),
IDENT => match p.nth(1) {
// Checks the token after an IDENT to see if a pattern is a path (Struct { .. }) or macro
// (T![x]).
T!['('] | T!['{'] | T![!] => path_or_macro_pat(p),
T![:] if p.nth_at(1, T![::]) => path_or_macro_pat(p),
_ => ident_pat(p, true),
},
// test type_path_in_pattern
// fn main() { let <_>::Foo = (); }
_ if paths::is_path_start(p) => path_or_macro_pat(p),
_ if is_literal_pat_start(p) => literal_pat(p),
T![_] => wildcard_pat(p),
T![&] => ref_pat(p),
T!['('] => tuple_pat(p),
T!['['] => slice_pat(p),
_ => {
p.err_recover("expected pattern", recovery_set);
return None;
}
};
Some(m)
}
fn is_literal_pat_start(p: &Parser<'_>) -> bool {
p.at(T![-]) && (p.nth(1) == INT_NUMBER || p.nth(1) == FLOAT_NUMBER)
|| p.at_ts(expressions::LITERAL_FIRST)
}
// test literal_pattern
// fn main() {
// match () {
// -1 => (),
// 92 => (),
// 'c' => (),
// "hello" => (),
// }
// }
fn literal_pat(p: &mut Parser<'_>) -> CompletedMarker {
assert!(is_literal_pat_start(p));
let m = p.start();
p.eat(T![-]);
expressions::literal(p);
m.complete(p, LITERAL_PAT)
}
// test path_part
// fn foo() {
// let foo::Bar = ();
// let ::Bar = ();
// let Bar { .. } = ();
// let Bar(..) = ();
// }
fn path_or_macro_pat(p: &mut Parser<'_>) -> CompletedMarker {
assert!(paths::is_path_start(p));
let m = p.start();
paths::expr_path(p);
let kind = match p.current() {
T!['('] => {
tuple_pat_fields(p);
TUPLE_STRUCT_PAT
}
T!['{'] => {
record_pat_field_list(p);
RECORD_PAT
}
// test marco_pat
// fn main() {
// let m!(x) = 0;
// }
T![!] => {
items::macro_call_after_excl(p);
return m.complete(p, MACRO_CALL).precede(p).complete(p, MACRO_PAT);
}
_ => PATH_PAT,
};
m.complete(p, kind)
}
// test tuple_pat_fields
// fn foo() {
// let S() = ();
// let S(_) = ();
// let S(_,) = ();
// let S(_, .. , x) = ();
// let S(| a) = ();
// }
fn tuple_pat_fields(p: &mut Parser<'_>) {
assert!(p.at(T!['(']));
p.bump(T!['(']);
pat_list(p, T![')']);
p.expect(T![')']);
}
// test record_pat_field
// fn foo() {
// let S { 0: 1 } = ();
// let S { x: 1 } = ();
// let S { #[cfg(any())] x: 1 } = ();
// }
fn record_pat_field(p: &mut Parser<'_>) {
match p.current() {
IDENT | INT_NUMBER if p.nth(1) == T![:] => {
name_ref_or_index(p);
p.bump(T![:]);
// test record_field_pat_leading_or
// fn foo() { let R { a: | 1 | 2 } = 0; }
pattern(p);
}
// test_err record_pat_field_eq_recovery
// fn main() {
// let S { field = foo };
// }
IDENT | INT_NUMBER if p.nth(1) == T![=] => {
name_ref_or_index(p);
p.err_and_bump("expected `:`");
pattern(p);
}
T![box] => {
// FIXME: not all box patterns should be allowed
box_pat(p);
}
T![ref] | T![mut] | IDENT => {
ident_pat(p, false);
}
_ => {
p.err_and_bump("expected identifier");
}
}
}
// test record_pat_field_list
// fn foo() {
// let S {} = ();
// let S { f, ref mut g } = ();
// let S { h: _, ..} = ();
// let S { h: _, } = ();
// let S { #[cfg(any())] .. } = ();
// }
fn record_pat_field_list(p: &mut Parser<'_>) {
assert!(p.at(T!['{']));
let m = p.start();
p.bump(T!['{']);
while !p.at(EOF) && !p.at(T!['}']) {
let m = p.start();
attributes::outer_attrs(p);
match p.current() {
// A trailing `..` is *not* treated as a REST_PAT.
T![.] if p.at(T![..]) => {
p.bump(T![..]);
m.complete(p, REST_PAT);
}
T!['{'] => {
error_block(p, "expected ident");
m.abandon(p);
}
_ => {
record_pat_field(p);
m.complete(p, RECORD_PAT_FIELD);
}
}
if !p.at(T!['}']) {
p.expect(T![,]);
}
}
p.expect(T!['}']);
m.complete(p, RECORD_PAT_FIELD_LIST);
}
// test placeholder_pat
// fn main() { let _ = (); }
fn wildcard_pat(p: &mut Parser<'_>) -> CompletedMarker {
assert!(p.at(T![_]));
let m = p.start();
p.bump(T![_]);
m.complete(p, WILDCARD_PAT)
}
// test ref_pat
// fn main() {
// let &a = ();
// let &mut b = ();
// }
fn ref_pat(p: &mut Parser<'_>) -> CompletedMarker {
assert!(p.at(T![&]));
let m = p.start();
p.bump(T![&]);
p.eat(T![mut]);
pattern_single(p);
m.complete(p, REF_PAT)
}
// test tuple_pat
// fn main() {
// let (a, b, ..) = ();
// let (a,) = ();
// let (..) = ();
// let () = ();
// let (| a | a, | b) = ((),());
// }
fn tuple_pat(p: &mut Parser<'_>) -> CompletedMarker {
assert!(p.at(T!['(']));
let m = p.start();
p.bump(T!['(']);
let mut has_comma = false;
let mut has_pat = false;
let mut has_rest = false;
// test_err tuple_pat_leading_comma
// fn foo() {
// let (,);
// }
if p.eat(T![,]) {
p.error("expected pattern");
has_comma = true;
}
while !p.at(EOF) && !p.at(T![')']) {
has_pat = true;
if !p.at_ts(PAT_TOP_FIRST) {
p.error("expected a pattern");
break;
}
has_rest |= p.at(T![..]);
pattern(p);
if !p.at(T![')']) {
has_comma = true;
p.expect(T![,]);
}
}
p.expect(T![')']);
m.complete(p, if !has_comma && !has_rest && has_pat { PAREN_PAT } else { TUPLE_PAT })
}
// test slice_pat
// fn main() {
// let [a, b, ..] = [];
// let [| a, ..] = [];
// }
fn slice_pat(p: &mut Parser<'_>) -> CompletedMarker {
assert!(p.at(T!['[']));
let m = p.start();
p.bump(T!['[']);
pat_list(p, T![']']);
p.expect(T![']']);
m.complete(p, SLICE_PAT)
}
fn pat_list(p: &mut Parser<'_>, ket: SyntaxKind) {
while !p.at(EOF) && !p.at(ket) {
pattern(p);
if !p.eat(T![,]) {
if p.at_ts(PAT_TOP_FIRST) {
p.error(format!("expected {:?}, got {:?}", T![,], p.current()));
} else {
break;
}
}
}
}
// test bind_pat
// fn main() {
// let a = ();
// let mut b = ();
// let ref c = ();
// let ref mut d = ();
// let e @ _ = ();
// let ref mut f @ g @ _ = ();
// }
fn ident_pat(p: &mut Parser<'_>, with_at: bool) -> CompletedMarker {
assert!(matches!(p.current(), T![ref] | T![mut] | IDENT));
let m = p.start();
p.eat(T![ref]);
p.eat(T![mut]);
name_r(p, PAT_RECOVERY_SET);
if with_at && p.eat(T![@]) {
pattern_single(p);
}
m.complete(p, IDENT_PAT)
}
// test box_pat
// fn main() {
// let box i = ();
// let box Outer { box i, j: box Inner(box &x) } = ();
// let box ref mut i = ();
// }
fn box_pat(p: &mut Parser<'_>) -> CompletedMarker {
assert!(p.at(T![box]));
let m = p.start();
p.bump(T![box]);
pattern_single(p);
m.complete(p, BOX_PAT)
}
// test const_block_pat
// fn main() {
// let const { 15 } = ();
// let const { foo(); bar() } = ();
//
// match 42 {
// const { 0 } .. const { 1 } => (),
// .. const { 0 } => (),
// const { 2 } .. => (),
// }
//
// let (const { () },) = ();
// }
fn const_block_pat(p: &mut Parser<'_>) -> CompletedMarker {
assert!(p.at(T![const]));
let m = p.start();
p.bump(T![const]);
expressions::block_expr(p);
m.complete(p, CONST_BLOCK_PAT)
}