parser/grammar/params.rs
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use crate::grammar::attributes::ATTRIBUTE_FIRST;
use super::*;
// test param_list
// fn a() {}
// fn b(x: i32) {}
// fn c(x: i32, ) {}
// fn d(x: i32, y: ()) {}
// test_err empty_param_slot
// fn f(y: i32, ,t: i32) {}
pub(super) fn param_list_fn_def(p: &mut Parser<'_>) {
list_(p, Flavor::FnDef);
}
pub(super) fn param_list_fn_ptr(p: &mut Parser<'_>) {
list_(p, Flavor::FnPointer);
}
pub(super) fn param_list_closure(p: &mut Parser<'_>) {
list_(p, Flavor::Closure);
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum Flavor {
FnDef, // Includes trait fn params; omitted param idents are not supported
FnPointer,
Closure,
}
fn list_(p: &mut Parser<'_>, flavor: Flavor) {
use Flavor::*;
let (bra, ket) = match flavor {
Closure => (T![|], T![|]),
FnDef | FnPointer => (T!['('], T![')']),
};
let list_marker = p.start();
p.bump(bra);
let mut param_marker = None;
if let FnDef = flavor {
// test self_param_outer_attr
// fn f(#[must_use] self) {}
let m = p.start();
attributes::outer_attrs(p);
match opt_self_param(p, m) {
Ok(()) => {}
Err(m) => param_marker = Some(m),
}
}
while !p.at(EOF) && !p.at(ket) {
// test param_outer_arg
// fn f(#[attr1] pat: Type) {}
let m = match param_marker.take() {
Some(m) => m,
None => {
let m = p.start();
attributes::outer_attrs(p);
m
}
};
if !p.at_ts(PARAM_FIRST.union(ATTRIBUTE_FIRST)) {
p.error("expected value parameter");
m.abandon(p);
if p.eat(T![,]) {
continue;
}
break;
}
param(p, m, flavor);
if !p.eat(T![,]) {
if p.at_ts(PARAM_FIRST.union(ATTRIBUTE_FIRST)) {
p.error("expected `,`");
} else {
break;
}
}
}
if let Some(m) = param_marker {
m.abandon(p);
}
p.expect(ket);
list_marker.complete(p, PARAM_LIST);
}
const PARAM_FIRST: TokenSet = patterns::PATTERN_FIRST.union(types::TYPE_FIRST);
fn param(p: &mut Parser<'_>, m: Marker, flavor: Flavor) {
match flavor {
// test param_list_vararg
// extern "C" { fn printf(format: *const i8, ..., _: u8) -> i32; }
Flavor::FnDef | Flavor::FnPointer if p.eat(T![...]) => {}
// test fn_def_param
// fn foo(..., (x, y): (i32, i32)) {}
Flavor::FnDef => {
patterns::pattern(p);
if !variadic_param(p) {
if p.at(T![:]) {
types::ascription(p);
} else {
// test_err missing_fn_param_type
// fn f(x y: i32, z, t: i32) {}
p.error("missing type for function parameter");
}
}
}
// test fn_pointer_param_ident_path
// type Foo = fn(Bar::Baz);
// type Qux = fn(baz: Bar::Baz);
// test fn_pointer_unnamed_arg
// type Foo = fn(_: bar);
Flavor::FnPointer => {
if (p.at(IDENT) || p.at(UNDERSCORE)) && p.nth(1) == T![:] && !p.nth_at(1, T![::]) {
patterns::pattern_single(p);
if !variadic_param(p) {
if p.at(T![:]) {
types::ascription(p);
} else {
p.error("missing type for function parameter");
}
}
} else {
types::type_(p);
}
}
// test closure_params
// fn main() {
// let foo = |bar, baz: Baz, qux: Qux::Quux| ();
// }
Flavor::Closure => {
patterns::pattern_single(p);
if p.at(T![:]) && !p.at(T![::]) {
types::ascription(p);
}
}
}
m.complete(p, PARAM);
}
fn variadic_param(p: &mut Parser<'_>) -> bool {
if p.at(T![:]) && p.nth_at(1, T![...]) {
p.bump(T![:]);
p.bump(T![...]);
true
} else {
false
}
}
// test self_param
// impl S {
// fn a(self) {}
// fn b(&self,) {}
// fn c(&'a self,) {}
// fn d(&'a mut self, x: i32) {}
// fn e(mut self) {}
// }
fn opt_self_param(p: &mut Parser<'_>, m: Marker) -> Result<(), Marker> {
if p.at(T![self]) || p.at(T![mut]) && p.nth(1) == T![self] {
p.eat(T![mut]);
self_as_name(p);
// test arb_self_types
// impl S {
// fn a(self: &Self) {}
// fn b(mut self: Box<Self>) {}
// }
if p.at(T![:]) {
types::ascription(p);
}
} else {
let la1 = p.nth(1);
let la2 = p.nth(2);
let la3 = p.nth(3);
if !matches!(
(p.current(), la1, la2, la3),
(T![&], T![self], _, _)
| (T![&], T![mut] | LIFETIME_IDENT, T![self], _)
| (T![&], LIFETIME_IDENT, T![mut], T![self])
) {
return Err(m);
}
p.bump(T![&]);
if p.at(LIFETIME_IDENT) {
lifetime(p);
}
p.eat(T![mut]);
self_as_name(p);
}
m.complete(p, SELF_PARAM);
if !p.at(T![')']) {
p.expect(T![,]);
}
Ok(())
}
fn self_as_name(p: &mut Parser<'_>) {
let m = p.start();
p.bump(T![self]);
m.complete(p, NAME);
}