Iterators which split strings on Grapheme Cluster or Word boundaries, according to the Unicode Standard Annex #29 rules.

Documentation
use unicode_segmentation::UnicodeSegmentation;
fn main() {
    let s = "a̐éö̲\r\n";
    let g = s.graphemes(true).collect::<Vec<&str>>();
    let b: &[_] = &["a̐", "é", "ö̲", "\r\n"];
    assert_eq!(g, b);
    let s = "The quick (\"brown\") fox can't jump 32.3 feet, right?";
    let w = s.unicode_words().collect::<Vec<&str>>();
    let b: &[_] = &["The", "quick", "brown", "fox", "can't", "jump", "32.3", "feet", "right"];
    assert_eq!(w, b);
    let s = "The quick (\"brown\")  fox";
    let w = s.split_word_bounds().collect::<Vec<&str>>();
    let b: &[_] = &["The", " ", "quick", " ", "(", "\"", "brown", "\"", ")", "  ", "fox"];
    assert_eq!(w, b);
}
no_std
unicode-segmentation does not depend on libstd, so it can be used in crates with the #![no_std] attribute.
crates.io
You can use this package in your project by adding the following to your Cargo.toml:
[dependencies]
unicode-segmentation = "1.10.1"
Change Log
1.11.0
- #124 Update data to Unicode 15.1
 - #128 Add 
size_hint to iterators 
1.10.1
- #113 Use criterion.rs for word benchmarks
 - #112 Improve table search speed through lookups
 
1.10.0
- #107 Upgrade to Unicode 15.0.0
 - #104 Supersedes and fixes #75
 
1.9.0
- #101 Upgrade to Unicode 14.0.0
 
1.8.0
- #100 * #100 - Increase 
#[inline] opportunities, resulting in 15-40% performance improvement. - #95 Implement debug for Graphemes
 - #94 Add Initial fuzzer for oss-fuzz integration
 - #93 Fix  unused imports and deprecated pattern warnings
 - #91 Made local variable immutable by moving it into loop
 - #91 Add new iterator UnicodeWordIndices and unicode_word_indices
 
1.7.1
- Update docs on version number
 
1.7.0
- #87 Upgrade to Unicode 13
 - #79 Implement a special-case lookup for ascii grapheme categories
 - #77 Optimization for grapheme iteration
 
1.6.0
- #72 Upgrade to Unicode 12
 
1.5.0
- #68 Upgrade to Unicode 11
 
1.4.0
- #56 Upgrade to Unicode 10
 
1.3.0
- #24 Add support for sentence boundaries
 - #44 Treat 
gc=No as a subset of gc=N 
1.2.1
- #37: Fix panic in 
provide_context. - #40: Fix crash in 
prev_boundary. 
1.2.0
- New 
GraphemeCursor API allows random access and bidirectional iteration. - Fixed incorrect splitting of certain emoji modifier sequences.
 
1.1.0
- Add 
as_str methods to the iterator types. 
1.0.3
- Code cleanup and additional tests.
 
1.0.1
- Fix a bug affecting some grapheme clusters containing Prepend characters.
 
1.0.0
- Upgrade to Unicode 9.0.0.