Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 848 insertions, 0 deletions

diff --git a/third_party/rust/rayon/src/str.rs b/third_party/rust/rayon/src/str.rs
new file mode 100644
index 0000000000..c85754e3d8
--- /dev/null
+++ b/third_party/rust/rayon/src/str.rs
@@ -0,0 +1,848 @@
+//! Parallel iterator types for [strings][std::str]
+//!
+//! You will rarely need to interact with this module directly unless you need
+//! to name one of the iterator types.
+//!
+//! Note: [`ParallelString::par_split()`] and [`par_split_terminator()`]
+//! reference a `Pattern` trait which is not visible outside this crate.
+//! This trait is intentionally kept private, for use only by Rayon itself.
+//! It is implemented for `char`, `&[char]`, and any function or closure
+//! `F: Fn(char) -> bool + Sync + Send`.
+//!
+//! [`ParallelString::par_split()`]: trait.ParallelString.html#method.par_split
+//! [`par_split_terminator()`]: trait.ParallelString.html#method.par_split_terminator
+//!
+//! [std::str]: https://doc.rust-lang.org/stable/std/str/
+
+use crate::iter::plumbing::*;
+use crate::iter::*;
+use crate::split_producer::*;
+
+/// Test if a byte is the start of a UTF-8 character.
+/// (extracted from `str::is_char_boundary`)
+#[inline]
+fn is_char_boundary(b: u8) -> bool {
+    // This is bit magic equivalent to: b < 128 || b >= 192
+    (b as i8) >= -0x40
+}
+
+/// Find the index of a character boundary near the midpoint.
+#[inline]
+fn find_char_midpoint(chars: &str) -> usize {
+    let mid = chars.len() / 2;
+
+    // We want to split near the midpoint, but we need to find an actual
+    // character boundary.  So we look at the raw bytes, first scanning
+    // forward from the midpoint for a boundary, then trying backward.
+    let (left, right) = chars.as_bytes().split_at(mid);
+    match right.iter().copied().position(is_char_boundary) {
+        Some(i) => mid + i,
+        None => left
+            .iter()
+            .copied()
+            .rposition(is_char_boundary)
+            .unwrap_or(0),
+    }
+}
+
+/// Try to split a string near the midpoint.
+#[inline]
+fn split(chars: &str) -> Option<(&str, &str)> {
+    let index = find_char_midpoint(chars);
+    if index > 0 {
+        Some(chars.split_at(index))
+    } else {
+        None
+    }
+}
+
+/// Parallel extensions for strings.
+pub trait ParallelString {
+    /// Returns a plain string slice, which is used to implement the rest of
+    /// the parallel methods.
+    fn as_parallel_string(&self) -> &str;
+
+    /// Returns a parallel iterator over the characters of a string.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rayon::prelude::*;
+    /// let max = "hello".par_chars().max_by_key(|c| *c as i32);
+    /// assert_eq!(Some('o'), max);
+    /// ```
+    fn par_chars(&self) -> Chars<'_> {
+        Chars {
+            chars: self.as_parallel_string(),
+        }
+    }
+
+    /// Returns a parallel iterator over the characters of a string, with their positions.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rayon::prelude::*;
+    /// let min = "hello".par_char_indices().min_by_key(|&(_i, c)| c as i32);
+    /// assert_eq!(Some((1, 'e')), min);
+    /// ```
+    fn par_char_indices(&self) -> CharIndices<'_> {
+        CharIndices {
+            chars: self.as_parallel_string(),
+        }
+    }
+
+    /// Returns a parallel iterator over the bytes of a string.
+    ///
+    /// Note that multi-byte sequences (for code points greater than `U+007F`)
+    /// are produced as separate items, but will not be split across threads.
+    /// If you would prefer an indexed iterator without that guarantee, consider
+    /// `string.as_bytes().par_iter().copied()` instead.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rayon::prelude::*;
+    /// let max = "hello".par_bytes().max();
+    /// assert_eq!(Some(b'o'), max);
+    /// ```
+    fn par_bytes(&self) -> Bytes<'_> {
+        Bytes {
+            chars: self.as_parallel_string(),
+        }
+    }
+
+    /// Returns a parallel iterator over a string encoded as UTF-16.
+    ///
+    /// Note that surrogate pairs (for code points greater than `U+FFFF`) are
+    /// produced as separate items, but will not be split across threads.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rayon::prelude::*;
+    ///
+    /// let max = "hello".par_encode_utf16().max();
+    /// assert_eq!(Some(b'o' as u16), max);
+    ///
+    /// let text = "Zażółć gęślą jaźń";
+    /// let utf8_len = text.len();
+    /// let utf16_len = text.par_encode_utf16().count();
+    /// assert!(utf16_len <= utf8_len);
+    /// ```
+    fn par_encode_utf16(&self) -> EncodeUtf16<'_> {
+        EncodeUtf16 {
+            chars: self.as_parallel_string(),
+        }
+    }
+
+    /// Returns a parallel iterator over substrings separated by a
+    /// given character or predicate, similar to `str::split`.
+    ///
+    /// Note: the `Pattern` trait is private, for use only by Rayon itself.
+    /// It is implemented for `char`, `&[char]`, and any function or closure
+    /// `F: Fn(char) -> bool + Sync + Send`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rayon::prelude::*;
+    /// let total = "1, 2, buckle, 3, 4, door"
+    ///    .par_split(',')
+    ///    .filter_map(|s| s.trim().parse::<i32>().ok())
+    ///    .sum();
+    /// assert_eq!(10, total);
+    /// ```
+    fn par_split<P: Pattern>(&self, separator: P) -> Split<'_, P> {
+        Split::new(self.as_parallel_string(), separator)
+    }
+
+    /// Returns a parallel iterator over substrings terminated by a
+    /// given character or predicate, similar to `str::split_terminator`.
+    /// It's equivalent to `par_split`, except it doesn't produce an empty
+    /// substring after a trailing terminator.
+    ///
+    /// Note: the `Pattern` trait is private, for use only by Rayon itself.
+    /// It is implemented for `char`, `&[char]`, and any function or closure
+    /// `F: Fn(char) -> bool + Sync + Send`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rayon::prelude::*;
+    /// let parts: Vec<_> = "((1 + 3) * 2)"
+    ///     .par_split_terminator(|c| c == '(' || c == ')')
+    ///     .collect();
+    /// assert_eq!(vec!["", "", "1 + 3", " * 2"], parts);
+    /// ```
+    fn par_split_terminator<P: Pattern>(&self, terminator: P) -> SplitTerminator<'_, P> {
+        SplitTerminator::new(self.as_parallel_string(), terminator)
+    }
+
+    /// Returns a parallel iterator over the lines of a string, ending with an
+    /// optional carriage return and with a newline (`\r\n` or just `\n`).
+    /// The final line ending is optional, and line endings are not included in
+    /// the output strings.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rayon::prelude::*;
+    /// let lengths: Vec<_> = "hello world\nfizbuzz"
+    ///     .par_lines()
+    ///     .map(|l| l.len())
+    ///     .collect();
+    /// assert_eq!(vec![11, 7], lengths);
+    /// ```
+    fn par_lines(&self) -> Lines<'_> {
+        Lines(self.as_parallel_string())
+    }
+
+    /// Returns a parallel iterator over the sub-slices of a string that are
+    /// separated by any amount of whitespace.
+    ///
+    /// As with `str::split_whitespace`, 'whitespace' is defined according to
+    /// the terms of the Unicode Derived Core Property `White_Space`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rayon::prelude::*;
+    /// let longest = "which is the longest word?"
+    ///     .par_split_whitespace()
+    ///     .max_by_key(|word| word.len());
+    /// assert_eq!(Some("longest"), longest);
+    /// ```
+    fn par_split_whitespace(&self) -> SplitWhitespace<'_> {
+        SplitWhitespace(self.as_parallel_string())
+    }
+
+    /// Returns a parallel iterator over substrings that match a
+    /// given character or predicate, similar to `str::matches`.
+    ///
+    /// Note: the `Pattern` trait is private, for use only by Rayon itself.
+    /// It is implemented for `char`, `&[char]`, and any function or closure
+    /// `F: Fn(char) -> bool + Sync + Send`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rayon::prelude::*;
+    /// let total = "1, 2, buckle, 3, 4, door"
+    ///    .par_matches(char::is_numeric)
+    ///    .map(|s| s.parse::<i32>().expect("digit"))
+    ///    .sum();
+    /// assert_eq!(10, total);
+    /// ```
+    fn par_matches<P: Pattern>(&self, pattern: P) -> Matches<'_, P> {
+        Matches {
+            chars: self.as_parallel_string(),
+            pattern,
+        }
+    }
+
+    /// Returns a parallel iterator over substrings that match a given character
+    /// or predicate, with their positions, similar to `str::match_indices`.
+    ///
+    /// Note: the `Pattern` trait is private, for use only by Rayon itself.
+    /// It is implemented for `char`, `&[char]`, and any function or closure
+    /// `F: Fn(char) -> bool + Sync + Send`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use rayon::prelude::*;
+    /// let digits: Vec<_> = "1, 2, buckle, 3, 4, door"
+    ///    .par_match_indices(char::is_numeric)
+    ///    .collect();
+    /// assert_eq!(digits, vec![(0, "1"), (3, "2"), (14, "3"), (17, "4")]);
+    /// ```
+    fn par_match_indices<P: Pattern>(&self, pattern: P) -> MatchIndices<'_, P> {
+        MatchIndices {
+            chars: self.as_parallel_string(),
+            pattern,
+        }
+    }
+}
+
+impl ParallelString for str {
+    #[inline]
+    fn as_parallel_string(&self) -> &str {
+        self
+    }
+}
+
+// /////////////////////////////////////////////////////////////////////////
+
+/// We hide the `Pattern` trait in a private module, as its API is not meant
+/// for general consumption.  If we could have privacy on trait items, then it
+/// would be nicer to have its basic existence and implementors public while
+/// keeping all of the methods private.
+mod private {
+    use crate::iter::plumbing::Folder;
+
+    /// Pattern-matching trait for `ParallelString`, somewhat like a mix of
+    /// `std::str::pattern::{Pattern, Searcher}`.
+    ///
+    /// Implementing this trait is not permitted outside of `rayon`.
+    pub trait Pattern: Sized + Sync + Send {
+        private_decl! {}
+        fn find_in(&self, haystack: &str) -> Option<usize>;
+        fn rfind_in(&self, haystack: &str) -> Option<usize>;
+        fn is_suffix_of(&self, haystack: &str) -> bool;
+        fn fold_splits<'ch, F>(&self, haystack: &'ch str, folder: F, skip_last: bool) -> F
+        where
+            F: Folder<&'ch str>;
+        fn fold_matches<'ch, F>(&self, haystack: &'ch str, folder: F) -> F
+        where
+            F: Folder<&'ch str>;
+        fn fold_match_indices<'ch, F>(&self, haystack: &'ch str, folder: F, base: usize) -> F
+        where
+            F: Folder<(usize, &'ch str)>;
+    }
+}
+use self::private::Pattern;
+
+#[inline]
+fn offset<T>(base: usize) -> impl Fn((usize, T)) -> (usize, T) {
+    move |(i, x)| (base + i, x)
+}
+
+macro_rules! impl_pattern {
+    (&$self:ident => $pattern:expr) => {
+        private_impl! {}
+
+        #[inline]
+        fn find_in(&$self, chars: &str) -> Option<usize> {
+            chars.find($pattern)
+        }
+
+        #[inline]
+        fn rfind_in(&$self, chars: &str) -> Option<usize> {
+            chars.rfind($pattern)
+        }
+
+        #[inline]
+        fn is_suffix_of(&$self, chars: &str) -> bool {
+            chars.ends_with($pattern)
+        }
+
+        fn fold_splits<'ch, F>(&$self, chars: &'ch str, folder: F, skip_last: bool) -> F
+        where
+            F: Folder<&'ch str>,
+        {
+            let mut split = chars.split($pattern);
+            if skip_last {
+                split.next_back();
+            }
+            folder.consume_iter(split)
+        }
+
+        fn fold_matches<'ch, F>(&$self, chars: &'ch str, folder: F) -> F
+        where
+            F: Folder<&'ch str>,
+        {
+            folder.consume_iter(chars.matches($pattern))
+        }
+
+        fn fold_match_indices<'ch, F>(&$self, chars: &'ch str, folder: F, base: usize) -> F
+        where
+            F: Folder<(usize, &'ch str)>,
+        {
+            folder.consume_iter(chars.match_indices($pattern).map(offset(base)))
+        }
+    }
+}
+
+impl Pattern for char {
+    impl_pattern!(&self => *self);
+}
+
+impl Pattern for &[char] {
+    impl_pattern!(&self => *self);
+}
+
+impl<FN: Sync + Send + Fn(char) -> bool> Pattern for FN {
+    impl_pattern!(&self => self);
+}
+
+// /////////////////////////////////////////////////////////////////////////
+
+/// Parallel iterator over the characters of a string
+#[derive(Debug, Clone)]
+pub struct Chars<'ch> {
+    chars: &'ch str,
+}
+
+struct CharsProducer<'ch> {
+    chars: &'ch str,
+}
+
+impl<'ch> ParallelIterator for Chars<'ch> {
+    type Item = char;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        bridge_unindexed(CharsProducer { chars: self.chars }, consumer)
+    }
+}
+
+impl<'ch> UnindexedProducer for CharsProducer<'ch> {
+    type Item = char;
+
+    fn split(self) -> (Self, Option<Self>) {
+        match split(self.chars) {
+            Some((left, right)) => (
+                CharsProducer { chars: left },
+                Some(CharsProducer { chars: right }),
+            ),
+            None => (self, None),
+        }
+    }
+
+    fn fold_with<F>(self, folder: F) -> F
+    where
+        F: Folder<Self::Item>,
+    {
+        folder.consume_iter(self.chars.chars())
+    }
+}
+
+// /////////////////////////////////////////////////////////////////////////
+
+/// Parallel iterator over the characters of a string, with their positions
+#[derive(Debug, Clone)]
+pub struct CharIndices<'ch> {
+    chars: &'ch str,
+}
+
+struct CharIndicesProducer<'ch> {
+    index: usize,
+    chars: &'ch str,
+}
+
+impl<'ch> ParallelIterator for CharIndices<'ch> {
+    type Item = (usize, char);
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        let producer = CharIndicesProducer {
+            index: 0,
+            chars: self.chars,
+        };
+        bridge_unindexed(producer, consumer)
+    }
+}
+
+impl<'ch> UnindexedProducer for CharIndicesProducer<'ch> {
+    type Item = (usize, char);
+
+    fn split(self) -> (Self, Option<Self>) {
+        match split(self.chars) {
+            Some((left, right)) => (
+                CharIndicesProducer {
+                    chars: left,
+                    ..self
+                },
+                Some(CharIndicesProducer {
+                    chars: right,
+                    index: self.index + left.len(),
+                }),
+            ),
+            None => (self, None),
+        }
+    }
+
+    fn fold_with<F>(self, folder: F) -> F
+    where
+        F: Folder<Self::Item>,
+    {
+        let base = self.index;
+        folder.consume_iter(self.chars.char_indices().map(offset(base)))
+    }
+}
+
+// /////////////////////////////////////////////////////////////////////////
+
+/// Parallel iterator over the bytes of a string
+#[derive(Debug, Clone)]
+pub struct Bytes<'ch> {
+    chars: &'ch str,
+}
+
+struct BytesProducer<'ch> {
+    chars: &'ch str,
+}
+
+impl<'ch> ParallelIterator for Bytes<'ch> {
+    type Item = u8;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        bridge_unindexed(BytesProducer { chars: self.chars }, consumer)
+    }
+}
+
+impl<'ch> UnindexedProducer for BytesProducer<'ch> {
+    type Item = u8;
+
+    fn split(self) -> (Self, Option<Self>) {
+        match split(self.chars) {
+            Some((left, right)) => (
+                BytesProducer { chars: left },
+                Some(BytesProducer { chars: right }),
+            ),
+            None => (self, None),
+        }
+    }
+
+    fn fold_with<F>(self, folder: F) -> F
+    where
+        F: Folder<Self::Item>,
+    {
+        folder.consume_iter(self.chars.bytes())
+    }
+}
+
+// /////////////////////////////////////////////////////////////////////////
+
+/// Parallel iterator over a string encoded as UTF-16
+#[derive(Debug, Clone)]
+pub struct EncodeUtf16<'ch> {
+    chars: &'ch str,
+}
+
+struct EncodeUtf16Producer<'ch> {
+    chars: &'ch str,
+}
+
+impl<'ch> ParallelIterator for EncodeUtf16<'ch> {
+    type Item = u16;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        bridge_unindexed(EncodeUtf16Producer { chars: self.chars }, consumer)
+    }
+}
+
+impl<'ch> UnindexedProducer for EncodeUtf16Producer<'ch> {
+    type Item = u16;
+
+    fn split(self) -> (Self, Option<Self>) {
+        match split(self.chars) {
+            Some((left, right)) => (
+                EncodeUtf16Producer { chars: left },
+                Some(EncodeUtf16Producer { chars: right }),
+            ),
+            None => (self, None),
+        }
+    }
+
+    fn fold_with<F>(self, folder: F) -> F
+    where
+        F: Folder<Self::Item>,
+    {
+        folder.consume_iter(self.chars.encode_utf16())
+    }
+}
+
+// /////////////////////////////////////////////////////////////////////////
+
+/// Parallel iterator over substrings separated by a pattern
+#[derive(Debug, Clone)]
+pub struct Split<'ch, P: Pattern> {
+    chars: &'ch str,
+    separator: P,
+}
+
+impl<'ch, P: Pattern> Split<'ch, P> {
+    fn new(chars: &'ch str, separator: P) -> Self {
+        Split { chars, separator }
+    }
+}
+
+impl<'ch, P: Pattern> ParallelIterator for Split<'ch, P> {
+    type Item = &'ch str;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        let producer = SplitProducer::new(self.chars, &self.separator);
+        bridge_unindexed(producer, consumer)
+    }
+}
+
+/// Implement support for `SplitProducer`.
+impl<'ch, P: Pattern> Fissile<P> for &'ch str {
+    fn length(&self) -> usize {
+        self.len()
+    }
+
+    fn midpoint(&self, end: usize) -> usize {
+        // First find a suitable UTF-8 boundary.
+        find_char_midpoint(&self[..end])
+    }
+
+    fn find(&self, separator: &P, start: usize, end: usize) -> Option<usize> {
+        separator.find_in(&self[start..end])
+    }
+
+    fn rfind(&self, separator: &P, end: usize) -> Option<usize> {
+        separator.rfind_in(&self[..end])
+    }
+
+    fn split_once(self, index: usize) -> (Self, Self) {
+        let (left, right) = self.split_at(index);
+        let mut right_iter = right.chars();
+        right_iter.next(); // skip the separator
+        (left, right_iter.as_str())
+    }
+
+    fn fold_splits<F>(self, separator: &P, folder: F, skip_last: bool) -> F
+    where
+        F: Folder<Self>,
+    {
+        separator.fold_splits(self, folder, skip_last)
+    }
+}
+
+// /////////////////////////////////////////////////////////////////////////
+
+/// Parallel iterator over substrings separated by a terminator pattern
+#[derive(Debug, Clone)]
+pub struct SplitTerminator<'ch, P: Pattern> {
+    chars: &'ch str,
+    terminator: P,
+}
+
+struct SplitTerminatorProducer<'ch, 'sep, P: Pattern> {
+    splitter: SplitProducer<'sep, P, &'ch str>,
+    skip_last: bool,
+}
+
+impl<'ch, P: Pattern> SplitTerminator<'ch, P> {
+    fn new(chars: &'ch str, terminator: P) -> Self {
+        SplitTerminator { chars, terminator }
+    }
+}
+
+impl<'ch, 'sep, P: Pattern + 'sep> SplitTerminatorProducer<'ch, 'sep, P> {
+    fn new(chars: &'ch str, terminator: &'sep P) -> Self {
+        SplitTerminatorProducer {
+            splitter: SplitProducer::new(chars, terminator),
+            skip_last: chars.is_empty() || terminator.is_suffix_of(chars),
+        }
+    }
+}
+
+impl<'ch, P: Pattern> ParallelIterator for SplitTerminator<'ch, P> {
+    type Item = &'ch str;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        let producer = SplitTerminatorProducer::new(self.chars, &self.terminator);
+        bridge_unindexed(producer, consumer)
+    }
+}
+
+impl<'ch, 'sep, P: Pattern + 'sep> UnindexedProducer for SplitTerminatorProducer<'ch, 'sep, P> {
+    type Item = &'ch str;
+
+    fn split(mut self) -> (Self, Option<Self>) {
+        let (left, right) = self.splitter.split();
+        self.splitter = left;
+        let right = right.map(|right| {
+            let skip_last = self.skip_last;
+            self.skip_last = false;
+            SplitTerminatorProducer {
+                splitter: right,
+                skip_last,
+            }
+        });
+        (self, right)
+    }
+
+    fn fold_with<F>(self, folder: F) -> F
+    where
+        F: Folder<Self::Item>,
+    {
+        self.splitter.fold_with(folder, self.skip_last)
+    }
+}
+
+// /////////////////////////////////////////////////////////////////////////
+
+/// Parallel iterator over lines in a string
+#[derive(Debug, Clone)]
+pub struct Lines<'ch>(&'ch str);
+
+#[inline]
+fn no_carriage_return(line: &str) -> &str {
+    line.strip_suffix('\r').unwrap_or(line)
+}
+
+impl<'ch> ParallelIterator for Lines<'ch> {
+    type Item = &'ch str;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.0
+            .par_split_terminator('\n')
+            .map(no_carriage_return)
+            .drive_unindexed(consumer)
+    }
+}
+
+// /////////////////////////////////////////////////////////////////////////
+
+/// Parallel iterator over substrings separated by whitespace
+#[derive(Debug, Clone)]
+pub struct SplitWhitespace<'ch>(&'ch str);
+
+#[inline]
+fn not_empty(s: &&str) -> bool {
+    !s.is_empty()
+}
+
+impl<'ch> ParallelIterator for SplitWhitespace<'ch> {
+    type Item = &'ch str;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        self.0
+            .par_split(char::is_whitespace)
+            .filter(not_empty)
+            .drive_unindexed(consumer)
+    }
+}
+
+// /////////////////////////////////////////////////////////////////////////
+
+/// Parallel iterator over substrings that match a pattern
+#[derive(Debug, Clone)]
+pub struct Matches<'ch, P: Pattern> {
+    chars: &'ch str,
+    pattern: P,
+}
+
+struct MatchesProducer<'ch, 'pat, P: Pattern> {
+    chars: &'ch str,
+    pattern: &'pat P,
+}
+
+impl<'ch, P: Pattern> ParallelIterator for Matches<'ch, P> {
+    type Item = &'ch str;
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        let producer = MatchesProducer {
+            chars: self.chars,
+            pattern: &self.pattern,
+        };
+        bridge_unindexed(producer, consumer)
+    }
+}
+
+impl<'ch, 'pat, P: Pattern> UnindexedProducer for MatchesProducer<'ch, 'pat, P> {
+    type Item = &'ch str;
+
+    fn split(self) -> (Self, Option<Self>) {
+        match split(self.chars) {
+            Some((left, right)) => (
+                MatchesProducer {
+                    chars: left,
+                    ..self
+                },
+                Some(MatchesProducer {
+                    chars: right,
+                    ..self
+                }),
+            ),
+            None => (self, None),
+        }
+    }
+
+    fn fold_with<F>(self, folder: F) -> F
+    where
+        F: Folder<Self::Item>,
+    {
+        self.pattern.fold_matches(self.chars, folder)
+    }
+}
+
+// /////////////////////////////////////////////////////////////////////////
+
+/// Parallel iterator over substrings that match a pattern, with their positions
+#[derive(Debug, Clone)]
+pub struct MatchIndices<'ch, P: Pattern> {
+    chars: &'ch str,
+    pattern: P,
+}
+
+struct MatchIndicesProducer<'ch, 'pat, P: Pattern> {
+    index: usize,
+    chars: &'ch str,
+    pattern: &'pat P,
+}
+
+impl<'ch, P: Pattern> ParallelIterator for MatchIndices<'ch, P> {
+    type Item = (usize, &'ch str);
+
+    fn drive_unindexed<C>(self, consumer: C) -> C::Result
+    where
+        C: UnindexedConsumer<Self::Item>,
+    {
+        let producer = MatchIndicesProducer {
+            index: 0,
+            chars: self.chars,
+            pattern: &self.pattern,
+        };
+        bridge_unindexed(producer, consumer)
+    }
+}
+
+impl<'ch, 'pat, P: Pattern> UnindexedProducer for MatchIndicesProducer<'ch, 'pat, P> {
+    type Item = (usize, &'ch str);
+
+    fn split(self) -> (Self, Option<Self>) {
+        match split(self.chars) {
+            Some((left, right)) => (
+                MatchIndicesProducer {
+                    chars: left,
+                    ..self
+                },
+                Some(MatchIndicesProducer {
+                    chars: right,
+                    index: self.index + left.len(),
+                    ..self
+                }),
+            ),
+            None => (self, None),
+        }
+    }
+
+    fn fold_with<F>(self, folder: F) -> F
+    where
+        F: Folder<Self::Item>,
+    {
+        self.pattern
+            .fold_match_indices(self.chars, folder, self.index)
+    }
+}