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Micro-optimize lookahead in composite tokens #5083

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Jun 26, 2020
Merged

Micro-optimize lookahead in composite tokens #5083

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15 changes: 11 additions & 4 deletions crates/ra_parser/src/parser.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -127,17 +127,24 @@ impl<'t> Parser<'t> {

fn at_composite2(&self, n: usize, k1: SyntaxKind, k2: SyntaxKind) -> bool {
let t1 = self.token_source.lookahead_nth(n);
if t1.kind != k1 || !t1.is_jointed_to_next {
return false;
}
let t2 = self.token_source.lookahead_nth(n + 1);
t1.kind == k1 && t1.is_jointed_to_next && t2.kind == k2
t2.kind == k2
}

fn at_composite3(&self, n: usize, k1: SyntaxKind, k2: SyntaxKind, k3: SyntaxKind) -> bool {
let t1 = self.token_source.lookahead_nth(n);
if t1.kind != k1 || !t1.is_jointed_to_next {
return false;
}
let t2 = self.token_source.lookahead_nth(n + 1);
if t2.kind != k2 || !t2.is_jointed_to_next {
return false;
}
let t3 = self.token_source.lookahead_nth(n + 2);
(t1.kind == k1 && t1.is_jointed_to_next)
&& (t2.kind == k2 && t2.is_jointed_to_next)
&& t3.kind == k3
t3.kind == k3
}

/// Checks if the current token is in `kinds`.
Expand Down