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Fix parsing of "postfix" range expressions.

Browse source 
Right now they are handled in `postfix_dot_expr`, but that doesn't allow it to
correctly handle precedence. Integrate it more tightly with the Pratt parser
instead.

Also includes a drive-by fix for parsing `match .. {}`.

Fixes #2242.
This commit is contained in:
Geoffry Song 2019-11-15 00:08:43 -08:00
parent 3ad11973ac
commit 989cebc99c
7 changed files with 142 additions and 30 deletions
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54
crates/ra_parser/src/grammar/expressions.rs
View file

@ -290,6 +290,25 @@ fn expr_bp(p: &mut Parser, r: Restrictions, bp: u8) -> (Option<CompletedMarker>,
let m = lhs.precede(p);
p.bump(op);
if is_range {
// test postfix_range
// fn foo() {
// let x = 1..;
// match 1.. { _ => () };
// match a.b()..S { _ => () };
// }
let has_trailing_expression =
p.at_ts(EXPR_FIRST) && !(r.forbid_structs && p.at(T!['{']));
if !has_trailing_expression {
if op == T![..=] {
p.error("expected expression to end inclusive range");
}
// no RHS
lhs = m.complete(p, RANGE_EXPR);
break;
}
}
expr_bp(p, r, op_bp + 1);
lhs = m.complete(p, if is_range { RANGE_EXPR } else { BIN_EXPR });
}
@ -330,7 +349,7 @@ fn lhs(p: &mut Parser, r: Restrictions) -> Option<(CompletedMarker, BlockLike)>
if p.at(op) {
m = p.start();
p.bump(op);
if p.at_ts(EXPR_FIRST) {
if p.at_ts(EXPR_FIRST) && !(r.forbid_structs && p.at(T!['{'])) {
expr_bp(p, r, 2);
}
return Some((m.complete(p, RANGE_EXPR), BlockLike::NotBlock));
@ -344,13 +363,7 @@ fn lhs(p: &mut Parser, r: Restrictions) -> Option<(CompletedMarker, BlockLike)>
// }
//
let (lhs, blocklike) = atom::atom_expr(p, r)?;
return Some(postfix_expr(
p,
lhs,
blocklike,
!(r.prefer_stmt && blocklike.is_block()),
r.forbid_structs,
));
return Some(postfix_expr(p, lhs, blocklike, !(r.prefer_stmt && blocklike.is_block())));
}
};
// parse the interior of the unary expression
@ -366,7 +379,6 @@ fn postfix_expr(
// `while true {break}; ();`
mut block_like: BlockLike,
mut allow_calls: bool,
forbid_structs: bool,
) -> (CompletedMarker, BlockLike) {
loop {
lhs = match p.current() {
@ -380,7 +392,7 @@ fn postfix_expr(
// }
T!['('] if allow_calls => call_expr(p, lhs),
T!['['] if allow_calls => index_expr(p, lhs),
T![.] => match postfix_dot_expr(p, lhs, forbid_structs) {
T![.] => match postfix_dot_expr(p, lhs) {
Ok(it) => it,
Err(it) => {
lhs = it;
@ -398,7 +410,6 @@ fn postfix_expr(
fn postfix_dot_expr(
p: &mut Parser,
lhs: CompletedMarker,
forbid_structs: bool,
) -> Result<CompletedMarker, CompletedMarker> {
assert!(p.at(T![.]));
if p.nth(1) == IDENT && (p.nth(2) == T!['('] || p.nth_at(2, T![::])) {
@ -418,25 +429,8 @@ fn postfix_expr(
return Ok(m.complete(p, AWAIT_EXPR));
}
// test postfix_range
// fn foo() {
// let x = 1..;
// match 1.. { _ => () };
// match a.b()..S { _ => () };
// }
for &(op, la) in &[(T![..=], 3), (T![..], 2)] {
if p.at(op) {
let next_token = p.nth(la);
let has_trailing_expression =
!(forbid_structs && next_token == T!['{']) && EXPR_FIRST.contains(next_token);
return if has_trailing_expression {
Err(lhs)
} else {
let m = lhs.precede(p);
p.bump(op);
Ok(m.complete(p, RANGE_EXPR))
};
}
if p.at(T![..=]) || p.at(T![..]) {
return Err(lhs);
}
Ok(field_expr(p, lhs))

3
crates/ra_syntax/test_data/parser/err/0038_endless_inclusive_range.rs Normal file
View file

@ -0,0 +1,3 @@
fn main() {
0..=;
}

24
crates/ra_syntax/test_data/parser/err/0038_endless_inclusive_range.txt Normal file
View file

@ -0,0 +1,24 @@
SOURCE_FILE@[0; 24)
FN_DEF@[0; 23)
FN_KW@[0; 2) "fn"
WHITESPACE@[2; 3) " "
NAME@[3; 7)
IDENT@[3; 7) "main"
PARAM_LIST@[7; 9)
L_PAREN@[7; 8) "("
R_PAREN@[8; 9) ")"
WHITESPACE@[9; 10) " "
BLOCK_EXPR@[10; 23)
BLOCK@[10; 23)
L_CURLY@[10; 11) "{"
WHITESPACE@[11; 16) "\n "
EXPR_STMT@[16; 21)
RANGE_EXPR@[16; 20)
LITERAL@[16; 17)
INT_NUMBER@[16; 17) "0"
DOTDOTEQ@[17; 20) "..="
SEMI@[20; 21) ";"
WHITESPACE@[21; 22) "\n"
R_CURLY@[22; 23) "}"
WHITESPACE@[23; 24) "\n"
error 20: expected expression to end inclusive range

4
crates/ra_syntax/test_data/parser/ok/0060_as_range.rs Normal file
View file

@ -0,0 +1,4 @@
fn main() {
0 as usize ..;
1 + 2 as usize ..;
}

56
crates/ra_syntax/test_data/parser/ok/0060_as_range.txt Normal file
View file

@ -0,0 +1,56 @@
SOURCE_FILE@[0; 56)
FN_DEF@[0; 55)
FN_KW@[0; 2) "fn"
WHITESPACE@[2; 3) " "
NAME@[3; 7)
IDENT@[3; 7) "main"
PARAM_LIST@[7; 9)
L_PAREN@[7; 8) "("
R_PAREN@[8; 9) ")"
WHITESPACE@[9; 10) " "
BLOCK_EXPR@[10; 55)
BLOCK@[10; 55)
L_CURLY@[10; 11) "{"
WHITESPACE@[11; 16) "\n "
EXPR_STMT@[16; 30)
RANGE_EXPR@[16; 29)
CAST_EXPR@[16; 26)
LITERAL@[16; 17)
INT_NUMBER@[16; 17) "0"
WHITESPACE@[17; 18) " "
AS_KW@[18; 20) "as"
WHITESPACE@[20; 21) " "
PATH_TYPE@[21; 26)
PATH@[21; 26)
PATH_SEGMENT@[21; 26)
NAME_REF@[21; 26)
IDENT@[21; 26) "usize"
WHITESPACE@[26; 27) " "
DOTDOT@[27; 29) ".."
SEMI@[29; 30) ";"
WHITESPACE@[30; 35) "\n "
EXPR_STMT@[35; 53)
RANGE_EXPR@[35; 52)
BIN_EXPR@[35; 49)
LITERAL@[35; 36)
INT_NUMBER@[35; 36) "1"
WHITESPACE@[36; 37) " "
PLUS@[37; 38) "+"
WHITESPACE@[38; 39) " "
CAST_EXPR@[39; 49)
LITERAL@[39; 40)
INT_NUMBER@[39; 40) "2"
WHITESPACE@[40; 41) " "
AS_KW@[41; 43) "as"
WHITESPACE@[43; 44) " "
PATH_TYPE@[44; 49)
PATH@[44; 49)
PATH_SEGMENT@[44; 49)
NAME_REF@[44; 49)
IDENT@[44; 49) "usize"
WHITESPACE@[49; 50) " "
DOTDOT@[50; 52) ".."
SEMI@[52; 53) ";"
WHITESPACE@[53; 54) "\n"
R_CURLY@[54; 55) "}"
WHITESPACE@[55; 56) "\n"

4
crates/ra_syntax/test_data/parser/ok/0061_match_full_range.rs Normal file
View file

@ -0,0 +1,4 @@
fn main() {
match .. {
}
}

27
crates/ra_syntax/test_data/parser/ok/0061_match_full_range.txt Normal file
View file

@ -0,0 +1,27 @@
SOURCE_FILE@[0; 35)
FN_DEF@[0; 34)
FN_KW@[0; 2) "fn"
WHITESPACE@[2; 3) " "
NAME@[3; 7)
IDENT@[3; 7) "main"
PARAM_LIST@[7; 9)
L_PAREN@[7; 8) "("
R_PAREN@[8; 9) ")"
WHITESPACE@[9; 10) " "
BLOCK_EXPR@[10; 34)
BLOCK@[10; 34)
L_CURLY@[10; 11) "{"
WHITESPACE@[11; 16) "\n "
MATCH_EXPR@[16; 32)
MATCH_KW@[16; 21) "match"
WHITESPACE@[21; 22) " "
RANGE_EXPR@[22; 24)
DOTDOT@[22; 24) ".."
WHITESPACE@[24; 25) " "
MATCH_ARM_LIST@[25; 32)
L_CURLY@[25; 26) "{"
WHITESPACE@[26; 31) "\n "
R_CURLY@[31; 32) "}"
WHITESPACE@[32; 33) "\n"
R_CURLY@[33; 34) "}"
WHITESPACE@[34; 35) "\n"