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Function tokenizer::preprocess 3x faster #66

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Merged
merged 5 commits into from
Dec 18, 2014
Merged

Function tokenizer::preprocess 3x faster #66

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ea6c1b7
Benchmark for preprocess function
ayosec Dec 18, 2014
9b4ec49
preprocess function in one pass
ayosec Dec 18, 2014
5f46180
Reduce match branches
ayosec Dec 18, 2014
0656606
Remove redundant UTF-8 check
ayosec Dec 18, 2014
2f08b15
Simplify match block removing code for multi-byte chars
ayosec Dec 18, 2014
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Simplify match block removing code for multi-byte chars
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@ayosec
ayosec committed Dec 18, 2014
commit 2f08b15c621e77e6446b14b2a3134c07b012a408
35 changes: 7 additions & 28 deletions src/tokenizer.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -43,36 +43,15 @@ fn preprocess(input: &str) -> String {
let bytes = input.as_bytes();
let mut result: Vec<u8> = Vec::with_capacity(bytes.len());
let mut last: u8 = 0;
let mut offset: uint = 0;
while offset < bytes.len() {
let byte = bytes[offset];
match byte {
b'\n' if last == b'\r' => (),
b'\r' | b'\n' | b'\x0C' => result.push(b'\n'),
b'\0' => result.push_all("\u{FFFD}".as_bytes()),
_ if byte < 128 => result.push(byte),
_ => {
// Multi-byte character
result.push(byte);
let remaining = bytes.len() - offset;
if remaining >= 3 && byte >= 0xF0 {
result.push(bytes[offset + 1]);
result.push(bytes[offset + 2]);
result.push(bytes[offset + 3]);
offset += 3;
} else if remaining >= 2 && byte >= 0xE0 {
result.push(bytes[offset + 1]);
result.push(bytes[offset + 2]);
offset += 2;
} else if remaining >= 1 && byte >= 0xC0 {
result.push(bytes[offset + 1]);
offset += 1;
}
}
for byte in bytes.iter() {
match *byte {
b'\n' if last == b'\r' => (),
b'\r' | b'\x0C' => result.push(b'\n'),
b'\0' => result.push_all("\u{FFFD}".as_bytes()),
_ => result.push(*byte),
}

last = byte;
offset += 1;
last = *byte;
}

unsafe { String::from_utf8_unchecked(result) }
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