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Merged
youknowone merged 4 commits into from
Feb 17, 2023
Merged

Optimize bytes-like (l|r)strip #4500

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f9f2be1
optimize bytes-like (l|r)strip
dannasman Feb 14, 2023
49a81d2
fix formatting
dannasman Feb 14, 2023
8b5e6aa
change return type of bytesinner (l|r)strip
dannasman Feb 16, 2023
e43d7b9
Merge branch 'RustPython:main' into bytes_lrstrip
dannasman Feb 16, 2023
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fix formatting
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@dannasman
dannasman committed Feb 14, 2023
commit 49a81d2003eafb2d66c8bb5b5991d55f25571eb4
12 changes: 10 additions & 2 deletions vm/src/builtins/bytes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -366,7 +366,11 @@ impl PyBytes {
}

#[pymethod]
fn lstrip(zelf: PyRef<Self>, chars: OptionalOption<PyBytesInner>, vm: &VirtualMachine) -> PyRef<Self> {
fn lstrip(
zelf: PyRef<Self>,
chars: OptionalOption<PyBytesInner>,
vm: &VirtualMachine,
) -> PyRef<Self> {
Comment on lines +369 to +373
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@youknowone youknowone Feb 15, 2023

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I found bytes.lstrip has different issue to str.lstrip. zelf.inner.lstrip already returns Vec<u8>, which means unnecessary copy happened.
I think this duplication check need to be done inside zelf.inner.lstip. otherwise zelf.inner.lstip also could return &[u8] instead of Vec<u8>, but it may not be easy due to lifetime.

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@dannasman dannasman Feb 15, 2023

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I see. If the zelf.inner.lstrip returns &[u8] is it possible to turn &[u8] to Vec<u8> without copying the values or is there a implementation for turning &[u8] directly to PyBytesInner? Because otherwise zelf.inner.elements is unnecessarily copied in the case of duplication.

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@dannasman dannasman Feb 15, 2023 •
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Could wrapping the return value of zelf.inner.lstrip in Option be an option? In that case it would return None on duplication and Some(stripped) would be returned in other cases.

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@fanninpm fanninpm Feb 16, 2023

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PyBytesInner is a wrapper around Vec<u8>, so allocation is inevitable. Fortunately, converting a Vec<u8> into a PyBytesInner only takes ownership of that Vec<u8>.

let stripped = zelf.inner.lstrip(chars);
if stripped == zelf.as_bytes().to_vec() {
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@fanninpm fanninpm Feb 15, 2023

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Does this work?

Suggested change
if stripped == zelf.as_bytes().to_vec() {
if stripped == zelf.as_bytes() {

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@youknowone youknowone Feb 16, 2023

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I think &stripped == zelf.as_bytes() works, but still stripped is Vec<u8>.

zelf
Expand All @@ -376,7 +380,11 @@ impl PyBytes {
}

#[pymethod]
fn rstrip(zelf: PyRef<Self>, chars: OptionalOption<PyBytesInner>, vm: &VirtualMachine) -> PyRef<Self> {
fn rstrip(
zelf: PyRef<Self>,
chars: OptionalOption<PyBytesInner>,
vm: &VirtualMachine,
) -> PyRef<Self> {
let stripped = zelf.inner.rstrip(chars);
if stripped == zelf.as_bytes().to_vec() {
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@fanninpm fanninpm Feb 15, 2023

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Suggested change
if stripped == zelf.as_bytes().to_vec() {
if stripped == zelf.as_bytes() {

zelf
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