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|
use crate::util::{
prefilter::PrefilterI,
search::{MatchKind, Span},
};
#[derive(Clone, Debug)]
pub(crate) struct Memmem {
#[cfg(not(all(feature = "std", feature = "perf-literal-substring")))]
_unused: (),
#[cfg(all(feature = "std", feature = "perf-literal-substring"))]
finder: memchr::memmem::Finder<'static>,
}
impl Memmem {
pub(crate) fn new<B: AsRef<[u8]>>(
_kind: MatchKind,
needles: &[B],
) -> Option<Memmem> {
#[cfg(not(all(feature = "std", feature = "perf-literal-substring")))]
{
None
}
#[cfg(all(feature = "std", feature = "perf-literal-substring"))]
{
if needles.len() != 1 {
return None;
}
let needle = needles[0].as_ref();
let finder = memchr::memmem::Finder::new(needle).into_owned();
Some(Memmem { finder })
}
}
}
impl PrefilterI for Memmem {
fn find(&self, haystack: &[u8], span: Span) -> Option<Span> {
#[cfg(not(all(feature = "std", feature = "perf-literal-substring")))]
{
unreachable!()
}
#[cfg(all(feature = "std", feature = "perf-literal-substring"))]
{
self.finder.find(&haystack[span]).map(|i| {
let start = span.start + i;
let end = start + self.finder.needle().len();
Span { start, end }
})
}
}
fn prefix(&self, haystack: &[u8], span: Span) -> Option<Span> {
#[cfg(not(all(feature = "std", feature = "perf-literal-substring")))]
{
unreachable!()
}
#[cfg(all(feature = "std", feature = "perf-literal-substring"))]
{
let needle = self.finder.needle();
if haystack[span].starts_with(needle) {
Some(Span { end: span.start + needle.len(), ..span })
} else {
None
}
}
}
fn memory_usage(&self) -> usize {
#[cfg(not(all(feature = "std", feature = "perf-literal-substring")))]
{
unreachable!()
}
#[cfg(all(feature = "std", feature = "perf-literal-substring"))]
{
self.finder.needle().len()
}
}
fn is_fast(&self) -> bool {
#[cfg(not(all(feature = "std", feature = "perf-literal-substring")))]
{
unreachable!()
}
#[cfg(all(feature = "std", feature = "perf-literal-substring"))]
{
true
}
}
}
|
