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|
mod atom;
pub(crate) use self::atom::match_arm_list;
pub(super) use self::atom::{literal, LITERAL_FIRST};
use super::*;
pub(super) enum StmtWithSemi {
Yes,
No,
Optional,
}
const EXPR_FIRST: TokenSet = LHS_FIRST;
pub(super) fn expr(p: &mut Parser) -> BlockLike {
let r = Restrictions { forbid_structs: false, prefer_stmt: false };
let mut dollar_lvl = 0;
expr_bp(p, r, 1, &mut dollar_lvl).1
}
pub(super) fn expr_stmt(p: &mut Parser) -> (Option<CompletedMarker>, BlockLike) {
let r = Restrictions { forbid_structs: false, prefer_stmt: true };
let mut dollar_lvl = 0;
expr_bp(p, r, 1, &mut dollar_lvl)
}
fn expr_no_struct(p: &mut Parser) {
let r = Restrictions { forbid_structs: true, prefer_stmt: false };
let mut dollar_lvl = 0;
expr_bp(p, r, 1, &mut dollar_lvl);
}
// test block
// fn a() {}
// fn b() { let _ = 1; }
// fn c() { 1; 2; }
// fn d() { 1; 2 }
pub(crate) fn block(p: &mut Parser) {
if !p.at(T!['{']) {
p.error("expected a block");
return;
}
let m = p.start();
p.bump();
expr_block_contents(p);
p.expect(T!['}']);
m.complete(p, BLOCK);
}
fn is_expr_stmt_attr_allowed(kind: SyntaxKind) -> bool {
match kind {
BIN_EXPR | RANGE_EXPR | IF_EXPR => false,
_ => true,
}
}
pub(super) fn stmt(p: &mut Parser, with_semi: StmtWithSemi) {
// test block_items
// fn a() { fn b() {} }
let m = p.start();
// test attr_on_expr_stmt
// fn foo() {
// #[A] foo();
// #[B] bar!{}
// #[C] #[D] {}
// #[D] return ();
// }
let has_attrs = p.at(T![#]);
attributes::outer_attributes(p);
if p.at(T![let]) {
let_stmt(p, m, with_semi);
return;
}
let m = match items::maybe_item(p, m, items::ItemFlavor::Mod) {
Ok(()) => return,
Err(m) => m,
};
let (cm, blocklike) = expr_stmt(p);
let kind = cm.as_ref().map(|cm| cm.kind()).unwrap_or(ERROR);
if has_attrs && !is_expr_stmt_attr_allowed(kind) {
// test_err attr_on_expr_not_allowed
// fn foo() {
// #[A] 1 + 2;
// #[B] if true {};
// }
p.error(format!("attributes are not allowed on {:?}", kind));
}
if p.at(T!['}']) {
// test attr_on_last_expr_in_block
// fn foo() {
// { #[A] bar!()? }
// #[B] &()
// }
if let Some(cm) = cm {
cm.undo_completion(p).abandon(p);
m.complete(p, kind);
} else {
m.abandon(p);
}
} else {
// test no_semi_after_block
// fn foo() {
// if true {}
// loop {}
// match () {}
// while true {}
// for _ in () {}
// {}
// {}
// macro_rules! test {
// () => {}
// }
// test!{}
// }
match with_semi {
StmtWithSemi::Yes => {
if blocklike.is_block() {
p.eat(T![;]);
} else {
p.expect(T![;]);
}
}
StmtWithSemi::No => {}
StmtWithSemi::Optional => {
if p.at(T![;]) {
p.eat(T![;]);
}
}
}
m.complete(p, EXPR_STMT);
}
// test let_stmt
// fn foo() {
// let a;
// let b: i32;
// let c = 92;
// let d: i32 = 92;
// let e: !;
// let _: ! = {};
// }
fn let_stmt(p: &mut Parser, m: Marker, with_semi: StmtWithSemi) {
assert!(p.at(T![let]));
p.bump();
patterns::pattern(p);
if p.at(T![:]) {
types::ascription(p);
}
if p.eat(T![=]) {
expressions::expr(p);
}
match with_semi {
StmtWithSemi::Yes => {
p.expect(T![;]);
}
StmtWithSemi::No => {}
StmtWithSemi::Optional => {
if p.at(T![;]) {
p.eat(T![;]);
}
}
}
m.complete(p, LET_STMT);
}
}
pub(crate) fn expr_block_contents(p: &mut Parser) {
// This is checked by a validator
attributes::inner_attributes(p);
while !p.at(EOF) && !p.at(T!['}']) {
// test nocontentexpr
// fn foo(){
// ;;;some_expr();;;;{;;;};;;;Ok(())
// }
// test nocontentexpr_after_item
// fn simple_function() {
// enum LocalEnum {
// One,
// Two,
// };
// fn f() {};
// struct S {};
// }
if p.current() == T![;] {
p.bump();
continue;
}
stmt(p, StmtWithSemi::Yes)
}
}
#[derive(Clone, Copy)]
struct Restrictions {
forbid_structs: bool,
prefer_stmt: bool,
}
enum Op {
Simple,
Composite(SyntaxKind, u8),
}
fn current_op(p: &Parser) -> (u8, Op) {
if let Some(t) = p.current3() {
match t {
(T![<], T![<], T![=]) => return (1, Op::Composite(T![<<=], 3)),
(T![>], T![>], T![=]) => return (1, Op::Composite(T![>>=], 3)),
_ => (),
}
}
if let Some(t) = p.current2() {
match t {
(T![+], T![=]) => return (1, Op::Composite(T![+=], 2)),
(T![-], T![=]) => return (1, Op::Composite(T![-=], 2)),
(T![*], T![=]) => return (1, Op::Composite(T![*=], 2)),
(T![%], T![=]) => return (1, Op::Composite(T![%=], 2)),
(T![/], T![=]) => return (1, Op::Composite(T![/=], 2)),
(T![|], T![=]) => return (1, Op::Composite(T![|=], 2)),
(T![&], T![=]) => return (1, Op::Composite(T![&=], 2)),
(T![^], T![=]) => return (1, Op::Composite(T![^=], 2)),
(T![|], T![|]) => return (3, Op::Composite(T![||], 2)),
(T![&], T![&]) => return (4, Op::Composite(T![&&], 2)),
(T![<], T![=]) => return (5, Op::Composite(T![<=], 2)),
(T![>], T![=]) => return (5, Op::Composite(T![>=], 2)),
(T![<], T![<]) => return (9, Op::Composite(T![<<], 2)),
(T![>], T![>]) => return (9, Op::Composite(T![>>], 2)),
_ => (),
}
}
let bp = match p.current() {
T![=] => 1,
T![..] | T![..=] => 2,
T![==] | T![!=] | T![<] | T![>] => 5,
T![|] => 6,
T![^] => 7,
T![&] => 8,
T![-] | T![+] => 10,
T![*] | T![/] | T![%] => 11,
_ => 0,
};
(bp, Op::Simple)
}
// Parses expression with binding power of at least bp.
fn expr_bp(
p: &mut Parser,
r: Restrictions,
mut bp: u8,
dollar_lvl: &mut usize,
) -> (Option<CompletedMarker>, BlockLike) {
// `newly_dollar_open` is a flag indicated that dollar is just closed after lhs, e.g.
// `$1$ + a`
// We use this flag to skip handling it.
let mut newly_dollar_open = if p.at_l_dollar() {
*dollar_lvl += p.eat_l_dollars();
true
} else {
false
};
let mut lhs = match lhs(p, r, dollar_lvl) {
Some((lhs, blocklike)) => {
// test stmt_bin_expr_ambiguity
// fn foo() {
// let _ = {1} & 2;
// {1} &2;
// }
if r.prefer_stmt && blocklike.is_block() {
return (Some(lhs), BlockLike::Block);
}
lhs
}
None => return (None, BlockLike::NotBlock),
};
loop {
if *dollar_lvl > 0 && p.at_r_dollar() {
*dollar_lvl -= p.eat_r_dollars(*dollar_lvl);
if !newly_dollar_open {
// We "pump" bp for make it highest priority
bp = 255;
}
newly_dollar_open = false;
}
let is_range = p.current() == T![..] || p.current() == T![..=];
let (op_bp, op) = current_op(p);
if op_bp < bp {
break;
}
let m = lhs.precede(p);
match op {
Op::Simple => p.bump(),
Op::Composite(kind, n) => {
p.bump_compound(kind, n);
}
}
expr_bp(p, r, op_bp + 1, dollar_lvl);
lhs = m.complete(p, if is_range { RANGE_EXPR } else { BIN_EXPR });
}
(Some(lhs), BlockLike::NotBlock)
}
const LHS_FIRST: TokenSet =
atom::ATOM_EXPR_FIRST.union(token_set![AMP, STAR, EXCL, DOTDOT, DOTDOTEQ, MINUS]);
fn lhs(
p: &mut Parser,
r: Restrictions,
dollar_lvl: &mut usize,
) -> Option<(CompletedMarker, BlockLike)> {
let m;
let kind = match p.current() {
// test ref_expr
// fn foo() {
// let _ = &1;
// let _ = &mut &f();
// }
T![&] => {
m = p.start();
p.bump();
p.eat(T![mut]);
REF_EXPR
}
// test unary_expr
// fn foo() {
// **&1;
// !!true;
// --1;
// }
T![*] | T![!] | T![-] => {
m = p.start();
p.bump();
PREFIX_EXPR
}
// test full_range_expr
// fn foo() { xs[..]; }
T![..] | T![..=] => {
m = p.start();
p.bump();
if p.at_ts(EXPR_FIRST) {
expr_bp(p, r, 2, dollar_lvl);
}
return Some((m.complete(p, RANGE_EXPR), BlockLike::NotBlock));
}
_ => {
let (lhs, blocklike) = atom::atom_expr(p, r)?;
return Some(postfix_expr(p, lhs, blocklike, !(r.prefer_stmt && blocklike.is_block())));
}
};
expr_bp(p, r, 255, dollar_lvl);
Some((m.complete(p, kind), BlockLike::NotBlock))
}
fn postfix_expr(
p: &mut Parser,
mut lhs: CompletedMarker,
// Calls are disallowed if the type is a block and we prefer statements because the call cannot be disambiguated from a tuple
// E.g. `while true {break}();` is parsed as
// `while true {break}; ();`
mut block_like: BlockLike,
mut allow_calls: bool,
) -> (CompletedMarker, BlockLike) {
loop {
lhs = match p.current() {
// test stmt_postfix_expr_ambiguity
// fn foo() {
// match () {
// _ => {}
// () => {}
// [] => {}
// }
// }
T!['('] if allow_calls => call_expr(p, lhs),
T!['['] if allow_calls => index_expr(p, lhs),
T![.] if p.nth(1) == IDENT && (p.nth(2) == T!['('] || p.nth(2) == T![::]) => {
method_call_expr(p, lhs)
}
T![.] if p.nth(1) == AWAIT_KW => {
// test await_expr
// fn foo() {
// x.await;
// x.0.await;
// x.0().await?.hello();
// }
let m = lhs.precede(p);
p.bump();
p.bump();
m.complete(p, AWAIT_EXPR)
}
T![.] => field_expr(p, lhs),
// test postfix_range
// fn foo() { let x = 1..; }
T![..] | T![..=] if !EXPR_FIRST.contains(p.nth(1)) => {
let m = lhs.precede(p);
p.bump();
m.complete(p, RANGE_EXPR)
}
T![?] => try_expr(p, lhs),
T![as] => cast_expr(p, lhs),
_ => break,
};
allow_calls = true;
block_like = BlockLike::NotBlock;
}
(lhs, block_like)
}
// test call_expr
// fn foo() {
// let _ = f();
// let _ = f()(1)(1, 2,);
// let _ = f(<Foo>::func());
// f(<Foo as Trait>::func());
// }
fn call_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker {
assert!(p.at(T!['(']));
let m = lhs.precede(p);
arg_list(p);
m.complete(p, CALL_EXPR)
}
// test index_expr
// fn foo() {
// x[1][2];
// }
fn index_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker {
assert!(p.at(T!['[']));
let m = lhs.precede(p);
p.bump();
expr(p);
p.expect(T![']']);
m.complete(p, INDEX_EXPR)
}
// test method_call_expr
// fn foo() {
// x.foo();
// y.bar::<T>(1, 2,);
// }
fn method_call_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker {
assert!(p.at(T![.]) && p.nth(1) == IDENT && (p.nth(2) == T!['('] || p.nth(2) == T![::]));
let m = lhs.precede(p);
p.bump();
name_ref(p);
type_args::opt_type_arg_list(p, true);
if p.at(T!['(']) {
arg_list(p);
}
m.complete(p, METHOD_CALL_EXPR)
}
// test field_expr
// fn foo() {
// x.foo;
// x.0.bar;
// x.0();
// }
// test_err bad_tuple_index_expr
// fn foo() {
// x.0.;
// x.1i32;
// x.0x01;
// }
#[allow(clippy::if_same_then_else)]
fn field_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker {
assert!(p.at(T![.]));
let m = lhs.precede(p);
p.bump();
if p.at(IDENT) {
name_ref(p)
} else if p.at(INT_NUMBER) {
p.bump();
} else if p.at(FLOAT_NUMBER) {
// FIXME: How to recover and instead parse INT + T![.]?
p.bump();
} else {
p.error("expected field name or number")
}
m.complete(p, FIELD_EXPR)
}
// test try_expr
// fn foo() {
// x?;
// }
fn try_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker {
assert!(p.at(T![?]));
let m = lhs.precede(p);
p.bump();
m.complete(p, TRY_EXPR)
}
// test cast_expr
// fn foo() {
// 82 as i32;
// 81 as i8 + 1;
// 79 as i16 - 1;
// 0x36 as u8 <= 0x37;
// }
fn cast_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker {
assert!(p.at(T![as]));
let m = lhs.precede(p);
p.bump();
// Use type_no_bounds(), because cast expressions are not
// allowed to have bounds.
types::type_no_bounds(p);
m.complete(p, CAST_EXPR)
}
fn arg_list(p: &mut Parser) {
assert!(p.at(T!['(']));
let m = p.start();
p.bump();
while !p.at(T![')']) && !p.at(EOF) {
if !p.at_ts(EXPR_FIRST) {
p.error("expected expression");
break;
}
expr(p);
if !p.at(T![')']) && !p.expect(T![,]) {
break;
}
}
p.eat(T![')']);
m.complete(p, ARG_LIST);
}
// test path_expr
// fn foo() {
// let _ = a;
// let _ = a::b;
// let _ = ::a::<b>;
// let _ = format!();
// }
fn path_expr(p: &mut Parser, r: Restrictions) -> (CompletedMarker, BlockLike) {
assert!(paths::is_path_start(p) || p.at(T![<]));
let m = p.start();
paths::expr_path(p);
match p.current() {
T!['{'] if !r.forbid_structs => {
named_field_list(p);
(m.complete(p, STRUCT_LIT), BlockLike::NotBlock)
}
T![!] => {
let block_like = items::macro_call_after_excl(p);
(m.complete(p, MACRO_CALL), block_like)
}
_ => (m.complete(p, PATH_EXPR), BlockLike::NotBlock),
}
}
// test struct_lit
// fn foo() {
// S {};
// S { x, y: 32, };
// S { x, y: 32, ..Default::default() };
// }
pub(crate) fn named_field_list(p: &mut Parser) {
assert!(p.at(T!['{']));
let m = p.start();
p.bump();
while !p.at(EOF) && !p.at(T!['}']) {
match p.current() {
// test struct_literal_field_with_attr
// fn main() {
// S { #[cfg(test)] field: 1 }
// }
IDENT | T![#] => {
let m = p.start();
attributes::outer_attributes(p);
name_ref(p);
if p.eat(T![:]) {
expr(p);
}
m.complete(p, NAMED_FIELD);
}
T![..] => {
p.bump();
expr(p);
}
T!['{'] => error_block(p, "expected a field"),
_ => p.err_and_bump("expected identifier"),
}
if !p.at(T!['}']) {
p.expect(T![,]);
}
}
p.expect(T!['}']);
m.complete(p, NAMED_FIELD_LIST);
}
|