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perf(cli): optimize html entity decoding with byte slice lookahead #661

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d-oit merged 2 commits into from
Oct 9, 2026
Merged

perf(cli): optimize html entity decoding with byte slice lookahead #661

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71fb7c3
perf(cli): optimize html entity decoding with byte slice lookahead
d-oit Oct 9, 2026
1767c3c
perf(cli): optimize html entity decoding with byte slice lookahead
d-oit Oct 9, 2026
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93 changes: 41 additions & 52 deletions cli/benches/decode_entities_bench.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -25,79 +25,68 @@ fn decode_entities_old(text: &str) -> String {
.replace("\u{2060}", "") // Remove word joiner
}

// Proposed optimized implementation
// Proposed optimized implementation using byte slice lookahead
fn decode_entities_optimized(text: &str) -> String {
if !text.contains('&') && !text.contains('\u{2060}') {
return text.to_string();
}

let mut result = String::with_capacity(text.len());
let mut chars = text.char_indices().peekable();
let bytes = text.as_bytes();
let len = bytes.len();
let mut result = String::with_capacity(len);
let mut i = 0;

while let Some((_, ch)) = chars.next() {
if ch == '&' {
let mut found_semi = false;
let mut end_idx = 0;
let temp_chars = chars.clone();
while i < len {
let b = bytes[i];

for (idx, next_ch) in temp_chars.take(10) {
if next_ch == ';' {
found_semi = true;
end_idx = idx + 1;
break;
}
}

if found_semi {
let start_idx = if let Some(&(idx, _)) = chars.peek() {
idx
} else {
end_idx
};

let entity = &text[start_idx..end_idx];
if b == b'&' {
let rest = &bytes[i + 1..];
let limit = rest.len().min(10);
if let Some(semi_pos) = rest[..limit].iter().position(|&c| c == b';') {
let entity = &text[i + 1..i + 1 + semi_pos];
let decoded = match entity {
"lt;" => Some("<"),
"gt;" => Some(">"),
"quot;" => Some("\""),
"#x27;" | "#39;" => Some("'"),
"nbsp;" => Some(" "),
"copy;" => Some("©"),
"reg;" => Some("®"),
"trade;" => Some("™"),
"ndash;" => Some("–"),
"mdash;" => Some("—"),
"lsquo;" => Some("‘"),
"rsquo;" => Some("’"),
"ldquo;" => Some("“"),
"rdquo;" => Some("”"),
"#91;" => Some("["),
"#93;" => Some("]"),
"#8288;" => Some(""),
"amp;" => Some("&"),
"lt" => Some("<"),
"gt" => Some(">"),
"quot" => Some("\""),
"#x27" | "#39" => Some("'"),
"nbsp" => Some(" "),
"copy" => Some("©"),
"reg" => Some("®"),
"trade" => Some("™"),
"ndash" => Some("–"),
"mdash" => Some("—"),
"lsquo" => Some("‘"),
"rsquo" => Some("’"),
"ldquo" => Some("“"),
"rdquo" => Some("”"),
"#91" => Some("["),
"#93" => Some("]"),
"#8288" => Some(""),
"amp" => Some("&"),
_ => None,
};

if let Some(d) = decoded {
result.push_str(d);
// Advance main iterator to after the semicolon
while let Some(&(idx, _)) = chars.peek() {
if idx < end_idx {
chars.next();
} else {
break;
}
}
i += 1 + semi_pos + 1;
continue;
}
}
}

if ch == '\u{2060}' {
if b == 0xE2 && i + 2 < len && bytes[i + 1] == 0x81 && bytes[i + 2] == 0xA0 {
i += 3;
continue;
}

result.push(ch);
if b.is_ascii() {
result.push(b as char);
i += 1;
} else {
let ch = text[i..].chars().next().unwrap();
result.push(ch);
i += ch.len_utf8();
}
}

result
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95 changes: 42 additions & 53 deletions cli/src/providers/direct_fetch.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -91,80 +91,69 @@ impl crate::providers::UrlProvider for DirectFetchProvider {
}
}

/// Decode basic HTML entities using a single-pass scanner for performance
/// Decode basic HTML entities using a byte-slice lookahead scanner for optimal performance
fn decode_entities(text: &str) -> String {
if !text.contains('&') && !text.contains('\u{2060}') {
return text.to_string();
}

let mut result = String::with_capacity(text.len());
let mut chars = text.char_indices().peekable();
let bytes = text.as_bytes();
let len = bytes.len();
let mut result = String::with_capacity(len);
let mut i = 0;

while let Some((_, ch)) = chars.next() {
if ch == '&' {
let mut found_semi = false;
let mut end_idx = 0;
let temp_chars = chars.clone();
while i < len {
let b = bytes[i];

for (idx, next_ch) in temp_chars.take(10) {
if next_ch == ';' {
found_semi = true;
end_idx = idx + 1;
break;
}
}

if found_semi {
let start_idx = if let Some(&(idx, _)) = chars.peek() {
idx
} else {
end_idx
};

let entity = &text[start_idx..end_idx];
if b == b'&' {
let rest = &bytes[i + 1..];
let limit = rest.len().min(10);
if let Some(semi_pos) = rest[..limit].iter().position(|&c| c == b';') {
let entity = &text[i + 1..i + 1 + semi_pos];
let decoded = match entity {
"lt;" => Some("<"),
"gt;" => Some(">"),
"quot;" => Some("\""),
"#x27;" | "#39;" => Some("'"),
"nbsp;" => Some(" "),
"copy;" => Some("©"),
"reg;" => Some("®"),
"trade;" => Some("™"),
"ndash;" => Some("–"),
"mdash;" => Some("—"),
"lsquo;" => Some("‘"),
"rsquo;" => Some("’"),
"ldquo;" => Some("“"),
"rdquo;" => Some("”"),
"#91;" => Some("["),
"#93;" => Some("]"),
"#8288;" => Some(""),
"amp;" => Some("&"),
"lt" => Some("<"),
"gt" => Some(">"),
"quot" => Some("\""),
"#x27" | "#39" => Some("'"),
"nbsp" => Some(" "),
"copy" => Some("©"),
"reg" => Some("®"),
"trade" => Some("™"),
"ndash" => Some("–"),
"mdash" => Some("—"),
"lsquo" => Some("‘"),
"rsquo" => Some("’"),
"ldquo" => Some("“"),
"rdquo" => Some("”"),
"#91" => Some("["),
"#93" => Some("]"),
"#8288" => Some(""),
"amp" => Some("&"),
_ => None,
};

if let Some(d) = decoded {
result.push_str(d);
// Advance main iterator to after the semicolon
while let Some(&(idx, _)) = chars.peek() {
if idx < end_idx {
chars.next();
} else {
break;
}
}
i += 1 + semi_pos + 1;
continue;
}
}
}

if ch == '\u{2060}' {
// Remove word joiner
// Byte check for \u{2060} word joiner (UTF-8 sequence: 0xE2 0x81 0xA0)
if b == 0xE2 && i + 2 < len && bytes[i + 1] == 0x81 && bytes[i + 2] == 0xA0 {
i += 3;
continue;
}

result.push(ch);
if b.is_ascii() {
result.push(b as char);
i += 1;
} else {
let ch = text[i..].chars().next().unwrap();
result.push(ch);
i += ch.len_utf8();
}
}

result
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