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syntax: Optimize some literal parsing #53521

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Merged
merged 1 commit into from
Aug 21, 2018
Merged

syntax: Optimize some literal parsing #53521

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10 changes: 4 additions & 6 deletions src/libsyntax/parse/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -532,7 +532,7 @@ fn byte_lit(lit: &str) -> (u8, usize) {
fn byte_str_lit(lit: &str) -> Lrc<Vec<u8>> {
let mut res = Vec::with_capacity(lit.len());

let error = |i| format!("lexer should have rejected {} at {}", lit, i);
let error = |i| panic!("lexer should have rejected {} at {}", lit, i);

/// Eat everything up to a non-whitespace
fn eat<I: Iterator<Item=(usize, u8)>>(it: &mut iter::Peekable<I>) {
Expand All @@ -551,12 +551,11 @@ fn byte_str_lit(lit: &str) -> Lrc<Vec<u8>> {
loop {
match chars.next() {
Some((i, b'\\')) => {
let em = error(i);
match chars.peek().expect(&em).1 {
match chars.peek().unwrap_or_else(|| error(i)).1 {
b'\n' => eat(&mut chars),
b'\r' => {
chars.next();
if chars.peek().expect(&em).1 != b'\n' {
if chars.peek().unwrap_or_else(|| error(i)).1 != b'\n' {
panic!("lexer accepted bare CR");
}
eat(&mut chars);
Expand All @@ -573,8 +572,7 @@ fn byte_str_lit(lit: &str) -> Lrc<Vec<u8>> {
}
},
Some((i, b'\r')) => {
let em = error(i);
if chars.peek().expect(&em).1 != b'\n' {
if chars.peek().unwrap_or_else(|| error(i)).1 != b'\n' {
panic!("lexer accepted bare CR");
}
chars.next();
Expand Down