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Make double ended string searchers use dependent fingers (fixes #47175)

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This commit is contained in:
Manish Goregaokar 2018-01-05 11:11:30 +05:30
parent dd582ac38e
commit ff55725a15
1 changed files with 10 additions and 6 deletions
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16
src/libcore/str/pattern.rs
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@ -284,7 +284,7 @@ unsafe impl<'a> Searcher<'a> for CharSearcher<'a> {
#[inline]
fn next(&mut self) -> SearchStep {
let old_finger = self.finger;
let slice = unsafe { self.haystack.get_unchecked(old_finger..self.haystack.len()) };
let slice = unsafe { self.haystack.get_unchecked(old_finger..self.finger_back) };
let mut iter = slice.chars();
let old_len = iter.iter.len();
if let Some(ch) = iter.next() {
@ -304,7 +304,8 @@ unsafe impl<'a> Searcher<'a> for CharSearcher<'a> {
fn next_match(&mut self) -> Option<(usize, usize)> {
loop {
// get the haystack after the last character found
let bytes = if let Some(slice) = self.haystack.as_bytes().get(self.finger..) {
let bytes = if let Some(slice) = self.haystack.as_bytes()
.get(self.finger..self.finger_back) {
slice
} else {
return None;
@ -340,7 +341,7 @@ unsafe impl<'a> Searcher<'a> for CharSearcher<'a> {
}
} else {
// found nothing, exit
self.finger = self.haystack.len();
self.finger = self.finger_back;
return None;
}
}
@ -353,7 +354,7 @@ unsafe impl<'a> ReverseSearcher<'a> for CharSearcher<'a> {
#[inline]
fn next_back(&mut self) -> SearchStep {
let old_finger = self.finger_back;
let slice = unsafe { self.haystack.slice_unchecked(0, old_finger) };
let slice = unsafe { self.haystack.slice_unchecked(self.finger, old_finger) };
let mut iter = slice.chars();
let old_len = iter.iter.len();
if let Some(ch) = iter.next_back() {
@ -374,7 +375,7 @@ unsafe impl<'a> ReverseSearcher<'a> for CharSearcher<'a> {
let haystack = self.haystack.as_bytes();
loop {
// get the haystack up to but not including the last character searched
let bytes = if let Some(slice) = haystack.get(..self.finger_back) {
let bytes = if let Some(slice) = haystack.get(self.finger..self.finger_back) {
slice
} else {
return None;
@ -382,6 +383,9 @@ unsafe impl<'a> ReverseSearcher<'a> for CharSearcher<'a> {
// the last byte of the utf8 encoded needle
let last_byte = unsafe { *self.utf8_encoded.get_unchecked(self.utf8_size - 1) };
if let Some(index) = memchr::memrchr(last_byte, bytes) {
// we searched a slice that was offset by self.finger,
// add self.finger to recoup the original index
let index = self.finger + index;
// memrchr will return the index of the byte we wish to
// find. In case of an ASCII character, this is indeed
// were we wish our new finger to be ("after" the found
@ -412,7 +416,7 @@ unsafe impl<'a> ReverseSearcher<'a> for CharSearcher<'a> {
// found the last byte when searching in reverse.
self.finger_back = index;
} else {
self.finger_back = 0;
self.finger_back = self.finger;
// found nothing, exit
return None;
}