bendns' repos / rust-analyzer
Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/parser/src/grammar/expressions.rs')
-rw-r--r--crates/parser/src/grammar/expressions.rs91
1 files changed, 52 insertions, 39 deletions
diff --git a/crates/parser/src/grammar/expressions.rs b/crates/parser/src/grammar/expressions.rs
index a884d8b6ec..1cbd166323 100644
--- a/crates/parser/src/grammar/expressions.rs
+++ b/crates/parser/src/grammar/expressions.rs
@@ -4,8 +4,8 @@ use crate::grammar::attributes::ATTRIBUTE_FIRST;
use super::*;
-pub(crate) use self::atom::{block_expr, match_arm_list};
-pub(super) use self::atom::{literal, LITERAL_FIRST};
+pub(crate) use atom::{block_expr, match_arm_list};
+pub(super) use atom::{literal, LITERAL_FIRST};
#[derive(PartialEq, Eq)]
pub(super) enum Semicolon {
@@ -188,47 +188,56 @@ struct Restrictions {
prefer_stmt: bool,
}
+enum Associativity {
+ Left,
+ Right,
+}
+
/// Binding powers of operators for a Pratt parser.
///
/// See <https://matklad.github.io/2020/04/13/simple-but-powerful-pratt-parsing.html>
+///
+/// Note that Rust doesn't define associativity for some infix operators (e.g. `==` and `..`) and
+/// requires parentheses to disambiguate. We just treat them as left associative.
#[rustfmt::skip]
-fn current_op(p: &Parser<'_>) -> (u8, SyntaxKind) {
- const NOT_AN_OP: (u8, SyntaxKind) = (0, T![@]);
+fn current_op(p: &Parser<'_>) -> (u8, SyntaxKind, Associativity) {
+ use Associativity::*;
+ const NOT_AN_OP: (u8, SyntaxKind, Associativity) = (0, T![@], Left);
match p.current() {
- T![|] if p.at(T![||]) => (3, T![||]),
- T![|] if p.at(T![|=]) => (1, T![|=]),
- T![|] => (6, T![|]),
- T![>] if p.at(T![>>=]) => (1, T![>>=]),
- T![>] if p.at(T![>>]) => (9, T![>>]),
- T![>] if p.at(T![>=]) => (5, T![>=]),
- T![>] => (5, T![>]),
+ T![|] if p.at(T![||]) => (3, T![||], Left),
+ T![|] if p.at(T![|=]) => (1, T![|=], Right),
+ T![|] => (6, T![|], Left),
+ T![>] if p.at(T![>>=]) => (1, T![>>=], Right),
+ T![>] if p.at(T![>>]) => (9, T![>>], Left),
+ T![>] if p.at(T![>=]) => (5, T![>=], Left),
+ T![>] => (5, T![>], Left),
T![=] if p.at(T![=>]) => NOT_AN_OP,
- T![=] if p.at(T![==]) => (5, T![==]),
- T![=] => (1, T![=]),
- T![<] if p.at(T![<=]) => (5, T![<=]),
- T![<] if p.at(T![<<=]) => (1, T![<<=]),
- T![<] if p.at(T![<<]) => (9, T![<<]),
- T![<] => (5, T![<]),
- T![+] if p.at(T![+=]) => (1, T![+=]),
- T![+] => (10, T![+]),
- T![^] if p.at(T![^=]) => (1, T![^=]),
- T![^] => (7, T![^]),
- T![%] if p.at(T![%=]) => (1, T![%=]),
- T![%] => (11, T![%]),
- T![&] if p.at(T![&=]) => (1, T![&=]),
+ T![=] if p.at(T![==]) => (5, T![==], Left),
+ T![=] => (1, T![=], Right),
+ T![<] if p.at(T![<=]) => (5, T![<=], Left),
+ T![<] if p.at(T![<<=]) => (1, T![<<=], Right),
+ T![<] if p.at(T![<<]) => (9, T![<<], Left),
+ T![<] => (5, T![<], Left),
+ T![+] if p.at(T![+=]) => (1, T![+=], Right),
+ T![+] => (10, T![+], Left),
+ T![^] if p.at(T![^=]) => (1, T![^=], Right),
+ T![^] => (7, T![^], Left),
+ T![%] if p.at(T![%=]) => (1, T![%=], Right),
+ T![%] => (11, T![%], Left),
+ T![&] if p.at(T![&=]) => (1, T![&=], Right),
// If you update this, remember to update `expr_let()` too.
- T![&] if p.at(T![&&]) => (4, T![&&]),
- T![&] => (8, T![&]),
- T![/] if p.at(T![/=]) => (1, T![/=]),
- T![/] => (11, T![/]),
- T![*] if p.at(T![*=]) => (1, T![*=]),
- T![*] => (11, T![*]),
- T![.] if p.at(T![..=]) => (2, T![..=]),
- T![.] if p.at(T![..]) => (2, T![..]),
- T![!] if p.at(T![!=]) => (5, T![!=]),
- T![-] if p.at(T![-=]) => (1, T![-=]),
- T![-] => (10, T![-]),
- T![as] => (12, T![as]),
+ T![&] if p.at(T![&&]) => (4, T![&&], Left),
+ T![&] => (8, T![&], Left),
+ T![/] if p.at(T![/=]) => (1, T![/=], Right),
+ T![/] => (11, T![/], Left),
+ T![*] if p.at(T![*=]) => (1, T![*=], Right),
+ T![*] => (11, T![*], Left),
+ T![.] if p.at(T![..=]) => (2, T![..=], Left),
+ T![.] if p.at(T![..]) => (2, T![..], Left),
+ T![!] if p.at(T![!=]) => (5, T![!=], Left),
+ T![-] if p.at(T![-=]) => (1, T![-=], Right),
+ T![-] => (10, T![-], Left),
+ T![as] => (12, T![as], Left),
_ => NOT_AN_OP
}
@@ -273,7 +282,7 @@ fn expr_bp(
loop {
let is_range = p.at(T![..]) || p.at(T![..=]);
- let (op_bp, op) = current_op(p);
+ let (op_bp, op, associativity) = current_op(p);
if op_bp < bp {
break;
}
@@ -306,7 +315,11 @@ fn expr_bp(
}
}
- expr_bp(p, None, Restrictions { prefer_stmt: false, ..r }, op_bp + 1);
+ let op_bp = match associativity {
+ Associativity::Left => op_bp + 1,
+ Associativity::Right => op_bp,
+ };
+ expr_bp(p, None, Restrictions { prefer_stmt: false, ..r }, op_bp);
lhs = m.complete(p, if is_range { RANGE_EXPR } else { BIN_EXPR });
}
Some((lhs, BlockLike::NotBlock))
@@ -417,7 +430,7 @@ fn postfix_expr(
allow_calls = true;
block_like = BlockLike::NotBlock;
}
- return (lhs, block_like);
+ (lhs, block_like)
}
fn postfix_dot_expr<const FLOAT_RECOVERY: bool>(