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Allow attributes on top level expression

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A top level expression is either
- a expression statement or
- the last expression in a block
This commit is contained in:
pcpthm 2019-03-19 17:24:02 +09:00
parent 1cd18f9237
commit ffed132e52
8 changed files with 231 additions and 35 deletions
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83
crates/ra_parser/src/grammar/expressions.rs
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@ -8,10 +8,10 @@ const EXPR_FIRST: TokenSet = LHS_FIRST;
pub(super) fn expr(p: &mut Parser) -> BlockLike {
let r = Restrictions { forbid_structs: false, prefer_stmt: false };
expr_bp(p, r, 1)
expr_bp(p, r, 1).1
}
pub(super) fn expr_stmt(p: &mut Parser) -> BlockLike {
pub(super) fn expr_stmt(p: &mut Parser) -> (Option<CompletedMarker>, BlockLike) {
let r = Restrictions { forbid_structs: false, prefer_stmt: true };
expr_bp(p, r, 1)
}
@ -55,7 +55,13 @@ pub(crate) fn expr_block_contents(p: &mut Parser) {
// test block_items
// fn a() { fn b() {} }
let m = p.start();
let has_attrs = p.at(POUND);
// test attr_on_expr_stmt
// fn foo() {
// #[A] foo();
// #[B] bar!{}
// #[C] #[D] {}
// #[D] return ();
// }
attributes::outer_attributes(p);
if p.at(LET_KW) {
let_stmt(p, m);
@ -67,35 +73,48 @@ pub(crate) fn expr_block_contents(p: &mut Parser) {
Err(m) => m,
};
if has_attrs {
m.abandon(p);
p.error("expected a let statement or an item after attributes in block");
} else {
let is_blocklike = expressions::expr_stmt(p) == BlockLike::Block;
if p.at(R_CURLY) {
m.abandon(p);
} else {
// test no_semi_after_block
// fn foo() {
// if true {}
// loop {}
// match () {}
// while true {}
// for _ in () {}
// {}
// {}
// macro_rules! test {
// () => {}
// }
// test!{}
// }
if is_blocklike {
p.eat(SEMI);
let (cm, blocklike) = expr_stmt(p);
let cm = match cm {
None => {
if p.at(R_CURLY) {
m.abandon(p);
} else {
p.expect(SEMI);
m.complete(p, EXPR_STMT);
}
m.complete(p, EXPR_STMT);
continue;
}
Some(cm) => cm,
};
if p.at(R_CURLY) {
// test attr_on_last_expr_in_block
// fn foo() {
// { #[A] bar!()? }
// #[B] &()
// }
m.contract_child(p, cm);
} else {
// test no_semi_after_block
// fn foo() {
// if true {}
// loop {}
// match () {}
// while true {}
// for _ in () {}
// {}
// {}
// macro_rules! test {
// () => {}
// }
// test!{}
// }
if blocklike.is_block() {
p.eat(SEMI);
} else {
p.expect(SEMI);
}
m.complete(p, EXPR_STMT);
}
}
@ -176,7 +195,7 @@ fn current_op(p: &Parser) -> (u8, Op) {
}
// Parses expression with binding power of at least bp.
fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) -> BlockLike {
fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) -> (Option<CompletedMarker>, BlockLike) {
let mut lhs = match lhs(p, r) {
Some((lhs, blocklike)) => {
// test stmt_bin_expr_ambiguity
@ -185,11 +204,11 @@ fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) -> BlockLike {
// {1} &2;
// }
if r.prefer_stmt && blocklike.is_block() {
return BlockLike::Block;
return (Some(lhs), BlockLike::Block);
}
lhs
}
None => return BlockLike::NotBlock,
None => return (None, BlockLike::NotBlock),
};
loop {
@ -208,7 +227,7 @@ fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) -> BlockLike {
expr_bp(p, r, op_bp + 1);
lhs = m.complete(p, if is_range { RANGE_EXPR } else { BIN_EXPR });
}
BlockLike::NotBlock
(Some(lhs), BlockLike::NotBlock)
}
const LHS_FIRST: TokenSet =