alamb commented on code in PR #6118:
URL: https://github.com/apache/arrow-rs/pull/6118#discussion_r1693931753
##########
arrow-string/src/predicate.rs:
##########
@@ -128,14 +130,32 @@ impl<'a> Predicate<'a> {
}
}
-fn starts_with_ignore_ascii_case(haystack: &str, needle: &str) -> bool {
- let end = haystack.len().min(needle.len());
- haystack.is_char_boundary(end) &&
needle.eq_ignore_ascii_case(&haystack[..end])
+fn starts_with(haystack: &str, needle: &str, byte_eq_kernel: impl Fn((&u8,
&u8)) -> bool) -> bool {
+ if needle.len() > haystack.len() {
+ false
+ } else {
+ std::iter::zip(haystack.as_bytes(),
needle.as_bytes()).all(byte_eq_kernel)
+ }
+}
+
+fn ends_with(haystack: &str, needle: &str, byte_eq_kernel: impl Fn((&u8, &u8))
-> bool) -> bool {
Review Comment:
```suggestion
/// This is faster than `str::starts_ends` for small strings. See
/// https://github.com/apache/arrow-rs/issues/6107
fn ends_with(haystack: &str, needle: &str, byte_eq_kernel: impl Fn((&u8,
&u8)) -> bool) -> bool {
```
##########
arrow-string/src/predicate.rs:
##########
@@ -128,14 +130,32 @@ impl<'a> Predicate<'a> {
}
}
-fn starts_with_ignore_ascii_case(haystack: &str, needle: &str) -> bool {
- let end = haystack.len().min(needle.len());
- haystack.is_char_boundary(end) &&
needle.eq_ignore_ascii_case(&haystack[..end])
+fn starts_with(haystack: &str, needle: &str, byte_eq_kernel: impl Fn((&u8,
&u8)) -> bool) -> bool {
Review Comment:
I think it might be worth leaving some comments here explaining that this
implementation is faster than std::str for shorter strings with a pointer to
the context
```suggestion
/// This is faster than `str::starts_with` for small strings. See
/// https://github.com/apache/arrow-rs/issues/6107
fn starts_with(haystack: &str, needle: &str, byte_eq_kernel: impl Fn((&u8,
&u8)) -> bool) -> bool {
```
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