core: skip emitting rejects if result doesn't cary it

library/alloc/src/str.rs

@@ -10,6 +10,7 @@
 use core::borrow::{Borrow, BorrowMut};
 use core::iter::FusedIterator;
 use core::mem::MaybeUninit;
+use core::pattern::{Pattern, Utf8Pattern};
 #[stable(feature = "encode_utf16", since = "1.8.0")]
 pub use core::str::EncodeUtf16;
 #[stable(feature = "split_ascii_whitespace", since = "1.34.0")]
@@ -20,7 +21,6 @@ pub use core::str::SplitInclusive;
 pub use core::str::SplitWhitespace;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::str::pattern;
-use core::str::pattern::{DoubleEndedSearcher, Pattern, ReverseSearcher, Searcher, Utf8Pattern};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::str::{Bytes, CharIndices, Chars, from_utf8, from_utf8_mut};
 #[stable(feature = "str_escape", since = "1.34.0")]
@@ -308,7 +308,10 @@ impl str {
                   without modifying the original"]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
-    pub fn replace<P: Pattern>(&self, from: P, to: &str) -> String {
+    pub fn replace<P>(&self, from: P, to: &str) -> String
+    where
+        P: Pattern<str>,
+    {
         // Fast path for replacing a single ASCII character with another.
         if let Some(from_byte) = match from.as_utf8_pattern() {
             Some(Utf8Pattern::StringPattern(s)) => match s.as_bytes() {
@@ -369,7 +372,10 @@ impl str {
     #[must_use = "this returns the replaced string as a new allocation, \
                   without modifying the original"]
     #[stable(feature = "str_replacen", since = "1.16.0")]
-    pub fn replacen<P: Pattern>(&self, pat: P, to: &str, count: usize) -> String {
+    pub fn replacen<P>(&self, pat: P, to: &str, count: usize) -> String
+    where
+        P: Pattern<str>,
+    {
         // Hope to reduce the times of re-allocation
         let mut result = String::with_capacity(32);
         let mut last_end = 0;

library/alloc/src/string.rs

@@ -53,7 +53,7 @@ use core::ops::Add;
 #[cfg(not(no_global_oom_handling))]
 use core::ops::AddAssign;
 use core::ops::{self, Range, RangeBounds};
-use core::str::pattern::{Pattern, Utf8Pattern};
+use core::pattern::{Pattern, Utf8Pattern};
 use core::{fmt, hash, hint, ptr, slice};
 
 #[cfg(not(no_global_oom_handling))]
@@ -1601,8 +1601,11 @@ impl String {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[unstable(feature = "string_remove_matches", issue = "72826")]
-    pub fn remove_matches<P: Pattern>(&mut self, pat: P) {
-        use core::str::pattern::Searcher;
+    pub fn remove_matches<'a, P>(&'a mut self, pat: P)
+    where
+        P: Pattern<str>,
+    {
+        use core::pattern::Searcher;
 
         let rejections = {
             let mut searcher = pat.into_searcher(self);
@@ -2165,7 +2168,10 @@ impl String {
     /// [replacen]: ../../std/primitive.str.html#method.replacen
     #[cfg(not(no_global_oom_handling))]
     #[unstable(feature = "string_replace_in_place", issue = "147949")]
-    pub fn replace_first<P: Pattern>(&mut self, from: P, to: &str) {
+    pub fn replace_first<'a, P>(&'a mut self, from: P, to: &str)
+    where
+        P: Pattern<str>,
+    {
         let range = match self.match_indices(from).next() {
             Some((start, match_str)) => start..start + match_str.len(),
             None => return,
@@ -2191,9 +2197,10 @@ impl String {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[unstable(feature = "string_replace_in_place", issue = "147949")]
-    pub fn replace_last<P: Pattern>(&mut self, from: P, to: &str)
+    pub fn replace_last<'a, P>(&'a mut self, from: P, to: &str)
     where
-        for<'a> P::Searcher<'a>: core::str::pattern::ReverseSearcher<'a>,
+        P: Pattern<str>,
+        for<'x> P::Searcher<'x>: core::pattern::ReverseSearcher<'x, str>,
     {
         let range = match self.rmatch_indices(from).next() {
             Some((start, match_str)) => start..start + match_str.len(),
@@ -2688,10 +2695,10 @@ impl<'a> Extend<&'a core::ascii::Char> for String {
     reason = "API not fully fleshed out and ready to be stabilized",
     issue = "27721"
 )]
-impl<'b> Pattern for &'b String {
-    type Searcher<'a> = <&'b str as Pattern>::Searcher<'a>;
+impl<'b> Pattern<str> for &'b String {
+    type Searcher<'h> = <&'b str as Pattern<str>>::Searcher<'h>;
 
-    fn into_searcher(self, haystack: &str) -> <&'b str as Pattern>::Searcher<'_> {
+    fn into_searcher<'h>(self, haystack: &'h str) -> <&'b str as Pattern<str>>::Searcher<'h> {
         self[..].into_searcher(haystack)
     }
 
@@ -2706,22 +2713,22 @@ impl<'b> Pattern for &'b String {
     }
 
     #[inline]
-    fn strip_prefix_of(self, haystack: &str) -> Option<&str> {
+    fn strip_prefix_of<'h>(self, haystack: &'h str) -> Option<&'h str> {
         self[..].strip_prefix_of(haystack)
     }
 
     #[inline]
-    fn is_suffix_of<'a>(self, haystack: &'a str) -> bool
+    fn is_suffix_of<'h>(self, haystack: &'h str) -> bool
     where
-        Self::Searcher<'a>: core::str::pattern::ReverseSearcher<'a>,
+        Self::Searcher<'h>: core::pattern::ReverseSearcher<'h, str>,
     {
         self[..].is_suffix_of(haystack)
     }
 
     #[inline]
-    fn strip_suffix_of<'a>(self, haystack: &'a str) -> Option<&'a str>
+    fn strip_suffix_of<'h>(self, haystack: &'h str) -> Option<&'h str>
     where
-        Self::Searcher<'a>: core::str::pattern::ReverseSearcher<'a>,
+        Self::Searcher<'h>: core::pattern::ReverseSearcher<'h, str>,
     {
         self[..].strip_suffix_of(haystack)
     }

library/alloctests/tests/str.rs

@@ -836,6 +836,18 @@ fn test_trim_matches() {
     assert_eq!("123foo1bar123".trim_matches(|c: char| c.is_numeric()), "foo1bar");
 }
 
+#[test]
+fn test_trim_matches_with_str_pattern() {
+    assert_eq!("abc".trim_start_matches("ab"), "c");
+    assert_eq!("xyzabcxyz".trim_start_matches("xyz"), "abcxyz");
+    assert_eq!("abcabc".trim_start_matches("abc"), "");
+    assert_eq!("ababab".trim_start_matches("ab"), "");
+
+    assert_eq!("abcab".trim_end_matches("ab"), "abc");
+    assert_eq!("xyzabcxyz".trim_end_matches("xyz"), "xyzabc");
+    assert_eq!("abcabc".trim_end_matches("abc"), "");
+}
+
 #[test]
 fn test_trim_start() {
     assert_eq!("".trim_start(), "");
@@ -2009,14 +2021,14 @@ fn test_repeat() {
 }
 
 mod pattern {
-    use std::str::pattern::SearchStep::{self, Done, Match, Reject};
-    use std::str::pattern::{Pattern, ReverseSearcher, Searcher};
+    use std::pattern::SearchStep::{self, Done, Match, Reject};
+    use std::pattern::{Pattern, ReverseSearcher, Searcher};
 
     macro_rules! make_test {
         ($name:ident, $p:expr, $h:expr, [$($e:expr,)*]) => {
             #[allow(unused_imports)]
             mod $name {
-                use std::str::pattern::SearchStep::{Match, Reject};
+                use std::pattern::SearchStep::{Match, Reject};
                 use super::{cmp_search_to_vec};
                 #[test]
                 fn fwd() {
@@ -2032,7 +2044,8 @@ mod pattern {
 
     fn cmp_search_to_vec<P>(rev: bool, pat: P, haystack: &str, right: Vec<SearchStep>)
     where
-        P: for<'a> Pattern<Searcher<'a>: ReverseSearcher<'a>>,
+        P: Pattern<str>,
+        for<'x> P::Searcher<'x>: ReverseSearcher<'x, str>,
     {
         let mut searcher = pat.into_searcher(haystack);
         let mut v = vec![];
@@ -2107,12 +2120,7 @@ mod pattern {
             Match(7, 7),
         ]
     );
-    make_test!(
-        str_searcher_multibyte_haystack,
-        " ",
-        "├──",
-        [Reject(0, 3), Reject(3, 6), Reject(6, 9),]
-    );
+    make_test!(str_searcher_multibyte_haystack, " ", "├──", [Reject(0, 9),]);
     make_test!(
         str_searcher_empty_needle_multibyte_haystack,
         "",
@@ -2143,18 +2151,8 @@ mod pattern {
             Reject(6, 7),
         ]
     );
-    make_test!(
-        char_searcher_multibyte_haystack,
-        ' ',
-        "├──",
-        [Reject(0, 3), Reject(3, 6), Reject(6, 9),]
-    );
-    make_test!(
-        char_searcher_short_haystack,
-        '\u{1F4A9}',
-        "* \t",
-        [Reject(0, 1), Reject(1, 2), Reject(2, 3),]
-    );
+    make_test!(char_searcher_multibyte_haystack, ' ', "├──", [Reject(0, 9),]);
+    make_test!(char_searcher_short_haystack, '\u{1F4A9}', "* \t", [Reject(0, 3),]);
 
     // See #85462
     #[test]
@@ -2196,6 +2194,21 @@ mod pattern {
             assert_eq!(searcher.next_back(), SearchStep::Done);
         }
     }
+
+    #[test]
+    fn str_searcher_empty_needle_interleaved() {
+        let mut searcher = "".into_searcher("abc");
+
+        assert_eq!(searcher.next(), SearchStep::Match(0, 0));
+        assert_eq!(searcher.next_back(), SearchStep::Match(3, 3));
+        assert_eq!(searcher.next(), SearchStep::Reject(0, 1));
+        assert_eq!(searcher.next_back(), SearchStep::Reject(2, 3));
+        assert_eq!(searcher.next(), SearchStep::Match(1, 1));
+        assert_eq!(searcher.next_back(), SearchStep::Match(2, 2));
+        assert_eq!(searcher.next(), SearchStep::Reject(1, 2));
+        assert_eq!(searcher.next_back(), SearchStep::Done);
+        assert_eq!(searcher.next(), SearchStep::Done);
+    }
 }
 
 macro_rules! generate_iterator_test {
@@ -2290,11 +2303,11 @@ generate_iterator_test! {
 
 #[test]
 fn different_str_pattern_forwarding_lifetimes() {
-    use std::str::pattern::Pattern;
+    use std::pattern::Pattern;
 
     fn foo<P>(p: P)
     where
-        for<'b> &'b P: Pattern,
+        for<'b> &'b P: Pattern<str>,
     {
         for _ in 0..3 {
             "asdf".find(&p);

library/core/src/lib.rs

@@ -326,8 +326,10 @@ pub mod unsafe_binder;
 
 pub mod fmt;
 pub mod hash;
+pub mod pattern;
 pub mod slice;
 pub mod str;
+pub mod str_bytes;
 pub mod time;
 
 pub mod wtf8;