Auto merge of #59591 - kennytm:needle-api, r=<try>

[WIP] Implement Needle API (RFC 2500)

cc #56345

----

Insta-stable changes:

* `impl Index<Range***> for OsStr` cannot be gated and is insta-stable.

I'll add more comments after the crater run.

Author: bors

src/liballoc/boxed.rs

@@ -78,6 +78,7 @@ use core::hash::{Hash, Hasher};
 use core::iter::{Iterator, FromIterator, FusedIterator};
 use core::marker::{Unpin, Unsize};
 use core::mem;
+use core::needle::Needle;
 use core::pin::Pin;
 use core::ops::{
     CoerceUnsized, DispatchFromDyn, Deref, DerefMut, Receiver, Generator, GeneratorState
@@ -919,3 +920,35 @@ impl<F: ?Sized + Future + Unpin> Future for Box<F> {
         F::poll(Pin::new(&mut *self), cx)
     }
 }
+
+#[unstable(feature = "needle", issue = "56345")]
+impl<'p, 'h, T: PartialEq + 'p + 'h> Needle<&'h [T]> for &'p Box<[T]> {
+    type Searcher = <&'p [T] as Needle<&'h [T]>>::Searcher;
+    type Consumer = <&'p [T] as Needle<&'h [T]>>::Consumer;
+
+    #[inline]
+    fn into_searcher(self) -> Self::Searcher {
+        <&'p [T] as Needle<&'h [T]>>::into_searcher(&**self)
+    }
+
+    #[inline]
+    fn into_consumer(self) -> Self::Consumer {
+        <&'p [T] as Needle<&'h [T]>>::into_consumer(&**self)
+    }
+}
+
+#[unstable(feature = "needle", issue = "56345")]
+impl<'p, 'h, T: PartialEq + 'p + 'h> Needle<&'h mut [T]> for &'p Box<[T]> {
+    type Searcher = <&'p [T] as Needle<&'h mut [T]>>::Searcher;
+    type Consumer = <&'p [T] as Needle<&'h mut [T]>>::Consumer;
+
+    #[inline]
+    fn into_searcher(self) -> Self::Searcher {
+        <&'p [T] as Needle<&'h mut [T]>>::into_searcher(&**self)
+    }
+
+    #[inline]
+    fn into_consumer(self) -> Self::Consumer {
+        <&'p [T] as Needle<&'h mut [T]>>::into_consumer(&**self)
+    }
+}

src/liballoc/lib.rs

@@ -91,7 +91,7 @@
 #![feature(needs_allocator)]
 #![feature(nll)]
 #![feature(optin_builtin_traits)]
-#![feature(pattern)]
+#![feature(needle)]
 #![feature(ptr_internals)]
 #![feature(ptr_offset_from)]
 #![feature(rustc_attrs)]

src/liballoc/slice.rs

@@ -92,6 +92,7 @@ use core::cmp::Ordering::{self, Less};
 use core::mem::{self, size_of};
 use core::ptr;
 use core::{u8, u16, u32};
+use core::needle::{ext, Needle, Searcher, Consumer};
 
 use crate::borrow::ToOwned;
 use crate::boxed::Box;
@@ -485,6 +486,40 @@ impl<T> [T] {
         }
         buf
     }
+
+    /// Replaces all matches of a predicate with another slice.
+    #[unstable(feature = "slice_needle_methods", issue = "56345")]
+    #[inline]
+    #[must_use = "this returns the replaced slice as a new allocation, \
+                  without modifying the original"]
+    pub fn replace<'s: 'a, 'a, F>(&'s self, from: F, to: &'a [T]) -> Vec<T>
+    where
+        T: Clone,
+        F: Needle<&'a [T]>,
+        F::Searcher: Searcher<[T]>, // FIXME: RFC 2089
+        F::Consumer: Consumer<[T]>, // FIXME: RFC 2089
+    {
+        let mut result = Vec::with_capacity(self.len());
+        ext::replace_with(self, from, |_| to, |s| result.extend_from_slice(s));
+        result
+    }
+
+    /// Replaces first N matches of a predicate with another slice.
+    #[unstable(feature = "slice_needle_methods", issue = "56345")]
+    #[inline]
+    #[must_use = "this returns the replaced slice as a new allocation, \
+                  without modifying the original"]
+    pub fn replacen<'s: 'a, 'a, F>(&'s self, from: F, to: &'a [T], count: usize) -> Vec<T>
+    where
+        T: Clone,
+        F: Needle<&'a [T]>,
+        F::Searcher: Searcher<[T]>, // FIXME: RFC 2089
+        F::Consumer: Consumer<[T]>, // FIXME: RFC 2089
+    {
+        let mut result = Vec::with_capacity(self.len());
+        ext::replacen_with(self, from, |_| to, count, |s| result.extend_from_slice(s));
+        result
+    }
 }
 
 #[lang = "slice_u8_alloc"]

src/liballoc/str.rs

@@ -28,14 +28,14 @@
 // It's cleaner to just turn off the unused_imports warning than to fix them.
 #![allow(unused_imports)]
 
-use core::borrow::Borrow;
-use core::str::pattern::{Pattern, Searcher, ReverseSearcher, DoubleEndedSearcher};
+use core::fmt;
+use core::needle::{ext, Needle, Searcher, Consumer};
 use core::mem;
 use core::ptr;
 use core::iter::FusedIterator;
 use core::unicode::conversions;
 
-use crate::borrow::ToOwned;
+use crate::borrow::{Borrow, ToOwned};
 use crate::boxed::Box;
 use crate::slice::{SliceConcatExt, SliceIndex};
 use crate::string::String;
@@ -62,8 +62,6 @@ pub use core::str::{from_utf8, from_utf8_mut, Chars, CharIndices, Bytes};
 pub use core::str::{from_utf8_unchecked, from_utf8_unchecked_mut, ParseBoolError};
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::str::SplitWhitespace;
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::str::pattern;
 #[stable(feature = "encode_utf16", since = "1.8.0")]
 pub use core::str::EncodeUtf16;
 #[stable(feature = "split_ascii_whitespace", since = "1.34.0")]
@@ -255,15 +253,14 @@ impl str {
                   without modifying the original"]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
-    pub fn replace<'a, P: Pattern<'a>>(&'a self, from: P, to: &str) -> String {
-        let mut result = String::new();
-        let mut last_end = 0;
-        for (start, part) in self.match_indices(from) {
-            result.push_str(unsafe { self.get_unchecked(last_end..start) });
-            result.push_str(to);
-            last_end = start + part.len();
-        }
-        result.push_str(unsafe { self.get_unchecked(last_end..self.len()) });
+    pub fn replace<'s: 'a, 'a, P>(&'s self, from: P, to: &'a str) -> String
+    where
+        P: Needle<&'a str>,
+        P::Searcher: Searcher<str>, // FIXME: RFC 2089
+        P::Consumer: Consumer<str>, // FIXME: RFC 2089
+    {
+        let mut result = String::with_capacity(self.len());
+        ext::replace_with(self, from, |_| to, |s| result.push_str(s));
         result
     }
 
@@ -295,16 +292,15 @@ 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<'a, P: Pattern<'a>>(&'a self, pat: P, to: &str, count: usize) -> String {
+    pub fn replacen<'s: 'a, 'a, P>(&'s self, pat: P, to: &'a str, count: usize) -> String
+    where
+        P: Needle<&'a str>,
+        P::Searcher: Searcher<str>, // FIXME: RFC 2089
+        P::Consumer: Consumer<str>, // FIXME: RFC 2089
+    {
         // Hope to reduce the times of re-allocation
-        let mut result = String::with_capacity(32);
-        let mut last_end = 0;
-        for (start, part) in self.match_indices(pat).take(count) {
-            result.push_str(unsafe { self.get_unchecked(last_end..start) });
-            result.push_str(to);
-            last_end = start + part.len();
-        }
-        result.push_str(unsafe { self.get_unchecked(last_end..self.len()) });
+        let mut result = String::with_capacity(self.len());
+        ext::replacen_with(self, pat, |_| to, count, |s| result.push_str(s));
         result
     }
 

src/liballoc/string.rs

@@ -53,7 +53,8 @@ use core::iter::{FromIterator, FusedIterator};
 use core::ops::{self, Add, AddAssign, Index, IndexMut, RangeBounds};
 use core::ops::Bound::{Excluded, Included, Unbounded};
 use core::ptr;
-use core::str::{pattern::Pattern, lossy};
+use core::needle::Needle;
+use core::str::lossy;
 
 use crate::borrow::{Cow, ToOwned};
 use crate::collections::CollectionAllocErr;
@@ -1792,24 +1793,19 @@ impl<'a> Extend<Cow<'a, str>> for String {
 }
 
 /// A convenience impl that delegates to the impl for `&str`
-#[unstable(feature = "pattern",
-           reason = "API not fully fleshed out and ready to be stabilized",
-           issue = "27721")]
-impl<'a, 'b> Pattern<'a> for &'b String {
-    type Searcher = <&'b str as Pattern<'a>>::Searcher;
-
-    fn into_searcher(self, haystack: &'a str) -> <&'b str as Pattern<'a>>::Searcher {
-        self[..].into_searcher(haystack)
-    }
+#[unstable(feature = "needle", issue = "56345")]
+impl<'a, 'b> Needle<&'a str> for &'b String {
+    type Searcher = <&'b str as Needle<&'a str>>::Searcher;
+    type Consumer = <&'b str as Needle<&'a str>>::Consumer;
 
     #[inline]
-    fn is_contained_in(self, haystack: &'a str) -> bool {
-        self[..].is_contained_in(haystack)
+    fn into_searcher(self) -> Self::Searcher {
+        <&'b str as Needle<&'a str>>::into_searcher(&**self)
     }
 
     #[inline]
-    fn is_prefix_of(self, haystack: &'a str) -> bool {
-        self[..].is_prefix_of(haystack)
+    fn into_consumer(self) -> Self::Consumer {
+        <&'b str as Needle<&'a str>>::into_consumer(&**self)
     }
 }
 

src/liballoc/tests/lib.rs

@@ -2,11 +2,13 @@
 #![feature(box_syntax)]
 #![feature(drain_filter)]
 #![feature(exact_size_is_empty)]
-#![feature(pattern)]
 #![feature(repeat_generic_slice)]
+#![feature(needle)]
 #![feature(try_reserve)]
 #![feature(unboxed_closures)]
 #![feature(vecdeque_rotate)]
+#![feature(mut_str_needle_methods)]
+#![feature(slice_needle_methods)]
 
 use std::hash::{Hash, Hasher};
 use std::collections::hash_map::DefaultHasher;