add Graphemes iterator; tidy unicode exports

- Graphemes and GraphemeIndices structs implement iterators over
  grapheme clusters analogous to the Chars and CharOffsets for chars in
  a string. Iterator and DoubleEndedIterator are available for both.

- tidied up the exports for libunicode. crate root exports are now moved
  into more appropriate module locations:
  - UnicodeStrSlice, Words, Graphemes, GraphemeIndices are in str module
  - UnicodeChar exported from char instead of crate root
  - canonical_combining_class is exported from str rather than crate root

Since libunicode's exports have changed, programs that previously relied
on the old export locations will need to change their `use` statements
to reflect the new ones. See above for more information on where the new
exports live.

closes #7043
[breaking-change]

1 files changed, 284 insertions, 6 deletions

diff --git a/src/libcollections/str.rs b/src/libcollections/str.rs
index 798046c461d..9e98088cf77 100644
--- a/src/libcollections/str.rs
+++ b/src/libcollections/str.rs
@@ -88,7 +88,7 @@ pub use core::str::{eq_slice, is_utf8, is_utf16, Utf16Items};
 pub use core::str::{Utf16Item, ScalarValue, LoneSurrogate, utf16_items};
 pub use core::str::{truncate_utf16_at_nul, utf8_char_width, CharRange};
 pub use core::str::{Str, StrSlice};
-pub use unicode::{Words, UnicodeStrSlice};
+pub use unicode::str::{UnicodeStrSlice, Words, Graphemes, GraphemeIndices};
 
 /*
 Section: Creating a string
@@ -284,8 +284,6 @@ pub struct Decompositions<'a> {
 impl<'a> Iterator<char> for Decompositions<'a> {
     #[inline]
     fn next(&mut self) -> Option<char> {
-        use unicode::canonical_combining_class;
-
         match self.buffer.as_slice().head() {
             Some(&(c, 0)) => {
                 self.sorted = false;
@@ -309,7 +307,7 @@ impl<'a> Iterator<char> for Decompositions<'a> {
                 let buffer = &mut self.buffer;
                 let sorted = &mut self.sorted;
                 decomposer(ch, |d| {
-                    let class = canonical_combining_class(d);
+                    let class = unicode::char::canonical_combining_class(d);
                     if class == 0 && !*sorted {
                         canonical_sort(buffer.as_mut_slice());
                         *sorted = true;
@@ -1021,7 +1019,7 @@ mod tests {
     use string::String;
     use vec::Vec;
 
-    use unicode::UnicodeChar;
+    use unicode::char::UnicodeChar;
 
     #[test]
     fn test_eq_slice() {
@@ -2110,7 +2108,7 @@ mod tests {
         assert_eq!("\u0301a".nfkd_chars().collect::<String>(),
                    String::from_str("\u0301a"));
         assert_eq!("\ud4db".nfkd_chars().collect::<String>(),
-String::from_str("\u1111\u1171\u11b6"));
+                   String::from_str("\u1111\u1171\u11b6"));
         assert_eq!("\uac1c".nfkd_chars().collect::<String>(), String::from_str("\u1100\u1162"));
     }
 
@@ -2126,6 +2124,286 @@ String::from_str("\u1111\u1171\u11b6"));
     }
 
     #[test]
+    fn test_graphemes() {
+        use std::iter::order;
+        // official Unicode test data
+        // from http://www.unicode.org/Public/UCD/latest/ucd/auxiliary/GraphemeBreakTest.txt
+        let test_same = [
+            ("\u0020\u0020", &["\u0020", "\u0020"]), ("\u0020\u0308\u0020", &["\u0020\u0308",
+            "\u0020"]), ("\u0020\u000D", &["\u0020", "\u000D"]), ("\u0020\u0308\u000D",
+            &["\u0020\u0308", "\u000D"]), ("\u0020\u000A", &["\u0020", "\u000A"]),
+            ("\u0020\u0308\u000A", &["\u0020\u0308", "\u000A"]), ("\u0020\u0001", &["\u0020",
+            "\u0001"]), ("\u0020\u0308\u0001", &["\u0020\u0308", "\u0001"]), ("\u0020\u0300",
+            &["\u0020\u0300"]), ("\u0020\u0308\u0300", &["\u0020\u0308\u0300"]), ("\u0020\u1100",
+            &["\u0020", "\u1100"]), ("\u0020\u0308\u1100", &["\u0020\u0308", "\u1100"]),
+            ("\u0020\u1160", &["\u0020", "\u1160"]), ("\u0020\u0308\u1160", &["\u0020\u0308",
+            "\u1160"]), ("\u0020\u11A8", &["\u0020", "\u11A8"]), ("\u0020\u0308\u11A8",
+            &["\u0020\u0308", "\u11A8"]), ("\u0020\uAC00", &["\u0020", "\uAC00"]),
+            ("\u0020\u0308\uAC00", &["\u0020\u0308", "\uAC00"]), ("\u0020\uAC01", &["\u0020",
+            "\uAC01"]), ("\u0020\u0308\uAC01", &["\u0020\u0308", "\uAC01"]), ("\u0020\U0001F1E6",
+            &["\u0020", "\U0001F1E6"]), ("\u0020\u0308\U0001F1E6", &["\u0020\u0308",
+            "\U0001F1E6"]), ("\u0020\u0378", &["\u0020", "\u0378"]), ("\u0020\u0308\u0378",
+            &["\u0020\u0308", "\u0378"]), ("\u000D\u0020", &["\u000D", "\u0020"]),
+            ("\u000D\u0308\u0020", &["\u000D", "\u0308", "\u0020"]), ("\u000D\u000D", &["\u000D",
+            "\u000D"]), ("\u000D\u0308\u000D", &["\u000D", "\u0308", "\u000D"]), ("\u000D\u000A",
+            &["\u000D\u000A"]), ("\u000D\u0308\u000A", &["\u000D", "\u0308", "\u000A"]),
+            ("\u000D\u0001", &["\u000D", "\u0001"]), ("\u000D\u0308\u0001", &["\u000D", "\u0308",
+            "\u0001"]), ("\u000D\u0300", &["\u000D", "\u0300"]), ("\u000D\u0308\u0300",
+            &["\u000D", "\u0308\u0300"]), ("\u000D\u0903", &["\u000D", "\u0903"]),
+            ("\u000D\u1100", &["\u000D", "\u1100"]), ("\u000D\u0308\u1100", &["\u000D", "\u0308",
+            "\u1100"]), ("\u000D\u1160", &["\u000D", "\u1160"]), ("\u000D\u0308\u1160",
+            &["\u000D", "\u0308", "\u1160"]), ("\u000D\u11A8", &["\u000D", "\u11A8"]),
+            ("\u000D\u0308\u11A8", &["\u000D", "\u0308", "\u11A8"]), ("\u000D\uAC00", &["\u000D",
+            "\uAC00"]), ("\u000D\u0308\uAC00", &["\u000D", "\u0308", "\uAC00"]), ("\u000D\uAC01",
+            &["\u000D", "\uAC01"]), ("\u000D\u0308\uAC01", &["\u000D", "\u0308", "\uAC01"]),
+            ("\u000D\U0001F1E6", &["\u000D", "\U0001F1E6"]), ("\u000D\u0308\U0001F1E6",
+            &["\u000D", "\u0308", "\U0001F1E6"]), ("\u000D\u0378", &["\u000D", "\u0378"]),
+            ("\u000D\u0308\u0378", &["\u000D", "\u0308", "\u0378"]), ("\u000A\u0020", &["\u000A",
+            "\u0020"]), ("\u000A\u0308\u0020", &["\u000A", "\u0308", "\u0020"]), ("\u000A\u000D",
+            &["\u000A", "\u000D"]), ("\u000A\u0308\u000D", &["\u000A", "\u0308", "\u000D"]),
+            ("\u000A\u000A", &["\u000A", "\u000A"]), ("\u000A\u0308\u000A", &["\u000A", "\u0308",
+            "\u000A"]), ("\u000A\u0001", &["\u000A", "\u0001"]), ("\u000A\u0308\u0001",
+            &["\u000A", "\u0308", "\u0001"]), ("\u000A\u0300", &["\u000A", "\u0300"]),
+            ("\u000A\u0308\u0300", &["\u000A", "\u0308\u0300"]), ("\u000A\u0903", &["\u000A",
+            "\u0903"]), ("\u000A\u1100", &["\u000A", "\u1100"]), ("\u000A\u0308\u1100",
+            &["\u000A", "\u0308", "\u1100"]), ("\u000A\u1160", &["\u000A", "\u1160"]),
+            ("\u000A\u0308\u1160", &["\u000A", "\u0308", "\u1160"]), ("\u000A\u11A8", &["\u000A",
+            "\u11A8"]), ("\u000A\u0308\u11A8", &["\u000A", "\u0308", "\u11A8"]), ("\u000A\uAC00",
+            &["\u000A", "\uAC00"]), ("\u000A\u0308\uAC00", &["\u000A", "\u0308", "\uAC00"]),
+            ("\u000A\uAC01", &["\u000A", "\uAC01"]), ("\u000A\u0308\uAC01", &["\u000A", "\u0308",
+            "\uAC01"]), ("\u000A\U0001F1E6", &["\u000A", "\U0001F1E6"]),
+            ("\u000A\u0308\U0001F1E6", &["\u000A", "\u0308", "\U0001F1E6"]), ("\u000A\u0378",
+            &["\u000A", "\u0378"]), ("\u000A\u0308\u0378", &["\u000A", "\u0308", "\u0378"]),
+            ("\u0001\u0020", &["\u0001", "\u0020"]), ("\u0001\u0308\u0020", &["\u0001", "\u0308",
+            "\u0020"]), ("\u0001\u000D", &["\u0001", "\u000D"]), ("\u0001\u0308\u000D",
+            &["\u0001", "\u0308", "\u000D"]), ("\u0001\u000A", &["\u0001", "\u000A"]),
+            ("\u0001\u0308\u000A", &["\u0001", "\u0308", "\u000A"]), ("\u0001\u0001", &["\u0001",
+            "\u0001"]), ("\u0001\u0308\u0001", &["\u0001", "\u0308", "\u0001"]), ("\u0001\u0300",
+            &["\u0001", "\u0300"]), ("\u0001\u0308\u0300", &["\u0001", "\u0308\u0300"]),
+            ("\u0001\u0903", &["\u0001", "\u0903"]), ("\u0001\u1100", &["\u0001", "\u1100"]),
+            ("\u0001\u0308\u1100", &["\u0001", "\u0308", "\u1100"]), ("\u0001\u1160", &["\u0001",
+            "\u1160"]), ("\u0001\u0308\u1160", &["\u0001", "\u0308", "\u1160"]), ("\u0001\u11A8",
+            &["\u0001", "\u11A8"]), ("\u0001\u0308\u11A8", &["\u0001", "\u0308", "\u11A8"]),
+            ("\u0001\uAC00", &["\u0001", "\uAC00"]), ("\u0001\u0308\uAC00", &["\u0001", "\u0308",
+            "\uAC00"]), ("\u0001\uAC01", &["\u0001", "\uAC01"]), ("\u0001\u0308\uAC01",
+            &["\u0001", "\u0308", "\uAC01"]), ("\u0001\U0001F1E6", &["\u0001", "\U0001F1E6"]),
+            ("\u0001\u0308\U0001F1E6", &["\u0001", "\u0308", "\U0001F1E6"]), ("\u0001\u0378",
+            &["\u0001", "\u0378"]), ("\u0001\u0308\u0378", &["\u0001", "\u0308", "\u0378"]),
+            ("\u0300\u0020", &["\u0300", "\u0020"]), ("\u0300\u0308\u0020", &["\u0300\u0308",
+            "\u0020"]), ("\u0300\u000D", &["\u0300", "\u000D"]), ("\u0300\u0308\u000D",
+            &["\u0300\u0308", "\u000D"]), ("\u0300\u000A", &["\u0300", "\u000A"]),
+            ("\u0300\u0308\u000A", &["\u0300\u0308", "\u000A"]), ("\u0300\u0001", &["\u0300",
+            "\u0001"]), ("\u0300\u0308\u0001", &["\u0300\u0308", "\u0001"]), ("\u0300\u0300",
+            &["\u0300\u0300"]), ("\u0300\u0308\u0300", &["\u0300\u0308\u0300"]), ("\u0300\u1100",
+            &["\u0300", "\u1100"]), ("\u0300\u0308\u1100", &["\u0300\u0308", "\u1100"]),
+            ("\u0300\u1160", &["\u0300", "\u1160"]), ("\u0300\u0308\u1160", &["\u0300\u0308",
+            "\u1160"]), ("\u0300\u11A8", &["\u0300", "\u11A8"]), ("\u0300\u0308\u11A8",
+            &["\u0300\u0308", "\u11A8"]), ("\u0300\uAC00", &["\u0300", "\uAC00"]),
+            ("\u0300\u0308\uAC00", &["\u0300\u0308", "\uAC00"]), ("\u0300\uAC01", &["\u0300",
+            "\uAC01"]), ("\u0300\u0308\uAC01", &["\u0300\u0308", "\uAC01"]), ("\u0300\U0001F1E6",
+            &["\u0300", "\U0001F1E6"]), ("\u0300\u0308\U0001F1E6", &["\u0300\u0308",
+            "\U0001F1E6"]), ("\u0300\u0378", &["\u0300", "\u0378"]), ("\u0300\u0308\u0378",
+            &["\u0300\u0308", "\u0378"]), ("\u0903\u0020", &["\u0903", "\u0020"]),
+            ("\u0903\u0308\u0020", &["\u0903\u0308", "\u0020"]), ("\u0903\u000D", &["\u0903",
+            "\u000D"]), ("\u0903\u0308\u000D", &["\u0903\u0308", "\u000D"]), ("\u0903\u000A",
+            &["\u0903", "\u000A"]), ("\u0903\u0308\u000A", &["\u0903\u0308", "\u000A"]),
+            ("\u0903\u0001", &["\u0903", "\u0001"]), ("\u0903\u0308\u0001", &["\u0903\u0308",
+            "\u0001"]), ("\u0903\u0300", &["\u0903\u0300"]), ("\u0903\u0308\u0300",
+            &["\u0903\u0308\u0300"]), ("\u0903\u1100", &["\u0903", "\u1100"]),
+            ("\u0903\u0308\u1100", &["\u0903\u0308", "\u1100"]), ("\u0903\u1160", &["\u0903",
+            "\u1160"]), ("\u0903\u0308\u1160", &["\u0903\u0308", "\u1160"]), ("\u0903\u11A8",
+            &["\u0903", "\u11A8"]), ("\u0903\u0308\u11A8", &["\u0903\u0308", "\u11A8"]),
+            ("\u0903\uAC00", &["\u0903", "\uAC00"]), ("\u0903\u0308\uAC00", &["\u0903\u0308",
+            "\uAC00"]), ("\u0903\uAC01", &["\u0903", "\uAC01"]), ("\u0903\u0308\uAC01",
+            &["\u0903\u0308", "\uAC01"]), ("\u0903\U0001F1E6", &["\u0903", "\U0001F1E6"]),
+            ("\u0903\u0308\U0001F1E6", &["\u0903\u0308", "\U0001F1E6"]), ("\u0903\u0378",
+            &["\u0903", "\u0378"]), ("\u0903\u0308\u0378", &["\u0903\u0308", "\u0378"]),
+            ("\u1100\u0020", &["\u1100", "\u0020"]), ("\u1100\u0308\u0020", &["\u1100\u0308",
+            "\u0020"]), ("\u1100\u000D", &["\u1100", "\u000D"]), ("\u1100\u0308\u000D",
+            &["\u1100\u0308", "\u000D"]), ("\u1100\u000A", &["\u1100", "\u000A"]),
+            ("\u1100\u0308\u000A", &["\u1100\u0308", "\u000A"]), ("\u1100\u0001", &["\u1100",
+            "\u0001"]), ("\u1100\u0308\u0001", &["\u1100\u0308", "\u0001"]), ("\u1100\u0300",
+            &["\u1100\u0300"]), ("\u1100\u0308\u0300", &["\u1100\u0308\u0300"]), ("\u1100\u1100",
+            &["\u1100\u1100"]), ("\u1100\u0308\u1100", &["\u1100\u0308", "\u1100"]),
+            ("\u1100\u1160", &["\u1100\u1160"]), ("\u1100\u0308\u1160", &["\u1100\u0308",
+            "\u1160"]), ("\u1100\u11A8", &["\u1100", "\u11A8"]), ("\u1100\u0308\u11A8",
+            &["\u1100\u0308", "\u11A8"]), ("\u1100\uAC00", &["\u1100\uAC00"]),
+            ("\u1100\u0308\uAC00", &["\u1100\u0308", "\uAC00"]), ("\u1100\uAC01",
+            &["\u1100\uAC01"]), ("\u1100\u0308\uAC01", &["\u1100\u0308", "\uAC01"]),
+            ("\u1100\U0001F1E6", &["\u1100", "\U0001F1E6"]), ("\u1100\u0308\U0001F1E6",
+            &["\u1100\u0308", "\U0001F1E6"]), ("\u1100\u0378", &["\u1100", "\u0378"]),
+            ("\u1100\u0308\u0378", &["\u1100\u0308", "\u0378"]), ("\u1160\u0020", &["\u1160",
+            "\u0020"]), ("\u1160\u0308\u0020", &["\u1160\u0308", "\u0020"]), ("\u1160\u000D",
+            &["\u1160", "\u000D"]), ("\u1160\u0308\u000D", &["\u1160\u0308", "\u000D"]),
+            ("\u1160\u000A", &["\u1160", "\u000A"]), ("\u1160\u0308\u000A", &["\u1160\u0308",
+            "\u000A"]), ("\u1160\u0001", &["\u1160", "\u0001"]), ("\u1160\u0308\u0001",
+            &["\u1160\u0308", "\u0001"]), ("\u1160\u0300", &["\u1160\u0300"]),
+            ("\u1160\u0308\u0300", &["\u1160\u0308\u0300"]), ("\u1160\u1100", &["\u1160",
+            "\u1100"]), ("\u1160\u0308\u1100", &["\u1160\u0308", "\u1100"]), ("\u1160\u1160",
+            &["\u1160\u1160"]), ("\u1160\u0308\u1160", &["\u1160\u0308", "\u1160"]),
+            ("\u1160\u11A8", &["\u1160\u11A8"]), ("\u1160\u0308\u11A8", &["\u1160\u0308",
+            "\u11A8"]), ("\u1160\uAC00", &["\u1160", "\uAC00"]), ("\u1160\u0308\uAC00",
+            &["\u1160\u0308", "\uAC00"]), ("\u1160\uAC01", &["\u1160", "\uAC01"]),
+            ("\u1160\u0308\uAC01", &["\u1160\u0308", "\uAC01"]), ("\u1160\U0001F1E6", &["\u1160",
+            "\U0001F1E6"]), ("\u1160\u0308\U0001F1E6", &["\u1160\u0308", "\U0001F1E6"]),
+            ("\u1160\u0378", &["\u1160", "\u0378"]), ("\u1160\u0308\u0378", &["\u1160\u0308",
+            "\u0378"]), ("\u11A8\u0020", &["\u11A8", "\u0020"]), ("\u11A8\u0308\u0020",
+            &["\u11A8\u0308", "\u0020"]), ("\u11A8\u000D", &["\u11A8", "\u000D"]),
+            ("\u11A8\u0308\u000D", &["\u11A8\u0308", "\u000D"]), ("\u11A8\u000A", &["\u11A8",
+            "\u000A"]), ("\u11A8\u0308\u000A", &["\u11A8\u0308", "\u000A"]), ("\u11A8\u0001",
+            &["\u11A8", "\u0001"]), ("\u11A8\u0308\u0001", &["\u11A8\u0308", "\u0001"]),
+            ("\u11A8\u0300", &["\u11A8\u0300"]), ("\u11A8\u0308\u0300", &["\u11A8\u0308\u0300"]),
+            ("\u11A8\u1100", &["\u11A8", "\u1100"]), ("\u11A8\u0308\u1100", &["\u11A8\u0308",
+            "\u1100"]), ("\u11A8\u1160", &["\u11A8", "\u1160"]), ("\u11A8\u0308\u1160",
+            &["\u11A8\u0308", "\u1160"]), ("\u11A8\u11A8", &["\u11A8\u11A8"]),
+            ("\u11A8\u0308\u11A8", &["\u11A8\u0308", "\u11A8"]), ("\u11A8\uAC00", &["\u11A8",
+            "\uAC00"]), ("\u11A8\u0308\uAC00", &["\u11A8\u0308", "\uAC00"]), ("\u11A8\uAC01",
+            &["\u11A8", "\uAC01"]), ("\u11A8\u0308\uAC01", &["\u11A8\u0308", "\uAC01"]),
+            ("\u11A8\U0001F1E6", &["\u11A8", "\U0001F1E6"]), ("\u11A8\u0308\U0001F1E6",
+            &["\u11A8\u0308", "\U0001F1E6"]), ("\u11A8\u0378", &["\u11A8", "\u0378"]),
+            ("\u11A8\u0308\u0378", &["\u11A8\u0308", "\u0378"]), ("\uAC00\u0020", &["\uAC00",
+            "\u0020"]), ("\uAC00\u0308\u0020", &["\uAC00\u0308", "\u0020"]), ("\uAC00\u000D",
+            &["\uAC00", "\u000D"]), ("\uAC00\u0308\u000D", &["\uAC00\u0308", "\u000D"]),
+            ("\uAC00\u000A", &["\uAC00", "\u000A"]), ("\uAC00\u0308\u000A", &["\uAC00\u0308",
+            "\u000A"]), ("\uAC00\u0001", &["\uAC00", "\u0001"]), ("\uAC00\u0308\u0001",
+            &["\uAC00\u0308", "\u0001"]), ("\uAC00\u0300", &["\uAC00\u0300"]),
+            ("\uAC00\u0308\u0300", &["\uAC00\u0308\u0300"]), ("\uAC00\u1100", &["\uAC00",
+            "\u1100"]), ("\uAC00\u0308\u1100", &["\uAC00\u0308", "\u1100"]), ("\uAC00\u1160",
+            &["\uAC00\u1160"]), ("\uAC00\u0308\u1160", &["\uAC00\u0308", "\u1160"]),
+            ("\uAC00\u11A8", &["\uAC00\u11A8"]), ("\uAC00\u0308\u11A8", &["\uAC00\u0308",
+            "\u11A8"]), ("\uAC00\uAC00", &["\uAC00", "\uAC00"]), ("\uAC00\u0308\uAC00",
+            &["\uAC00\u0308", "\uAC00"]), ("\uAC00\uAC01", &["\uAC00", "\uAC01"]),
+            ("\uAC00\u0308\uAC01", &["\uAC00\u0308", "\uAC01"]), ("\uAC00\U0001F1E6", &["\uAC00",
+            "\U0001F1E6"]), ("\uAC00\u0308\U0001F1E6", &["\uAC00\u0308", "\U0001F1E6"]),
+            ("\uAC00\u0378", &["\uAC00", "\u0378"]), ("\uAC00\u0308\u0378", &["\uAC00\u0308",
+            "\u0378"]), ("\uAC01\u0020", &["\uAC01", "\u0020"]), ("\uAC01\u0308\u0020",
+            &["\uAC01\u0308", "\u0020"]), ("\uAC01\u000D", &["\uAC01", "\u000D"]),
+            ("\uAC01\u0308\u000D", &["\uAC01\u0308", "\u000D"]), ("\uAC01\u000A", &["\uAC01",
+            "\u000A"]), ("\uAC01\u0308\u000A", &["\uAC01\u0308", "\u000A"]), ("\uAC01\u0001",
+            &["\uAC01", "\u0001"]), ("\uAC01\u0308\u0001", &["\uAC01\u0308", "\u0001"]),
+            ("\uAC01\u0300", &["\uAC01\u0300"]), ("\uAC01\u0308\u0300", &["\uAC01\u0308\u0300"]),
+            ("\uAC01\u1100", &["\uAC01", "\u1100"]), ("\uAC01\u0308\u1100", &["\uAC01\u0308",
+            "\u1100"]), ("\uAC01\u1160", &["\uAC01", "\u1160"]), ("\uAC01\u0308\u1160",
+            &["\uAC01\u0308", "\u1160"]), ("\uAC01\u11A8", &["\uAC01\u11A8"]),
+            ("\uAC01\u0308\u11A8", &["\uAC01\u0308", "\u11A8"]), ("\uAC01\uAC00", &["\uAC01",
+            "\uAC00"]), ("\uAC01\u0308\uAC00", &["\uAC01\u0308", "\uAC00"]), ("\uAC01\uAC01",
+            &["\uAC01", "\uAC01"]), ("\uAC01\u0308\uAC01", &["\uAC01\u0308", "\uAC01"]),
+            ("\uAC01\U0001F1E6", &["\uAC01", "\U0001F1E6"]), ("\uAC01\u0308\U0001F1E6",
+            &["\uAC01\u0308", "\U0001F1E6"]), ("\uAC01\u0378", &["\uAC01", "\u0378"]),
+            ("\uAC01\u0308\u0378", &["\uAC01\u0308", "\u0378"]), ("\U0001F1E6\u0020",
+            &["\U0001F1E6", "\u0020"]), ("\U0001F1E6\u0308\u0020", &["\U0001F1E6\u0308",
+            "\u0020"]), ("\U0001F1E6\u000D", &["\U0001F1E6", "\u000D"]),
+            ("\U0001F1E6\u0308\u000D", &["\U0001F1E6\u0308", "\u000D"]), ("\U0001F1E6\u000A",
+            &["\U0001F1E6", "\u000A"]), ("\U0001F1E6\u0308\u000A", &["\U0001F1E6\u0308",
+            "\u000A"]), ("\U0001F1E6\u0001", &["\U0001F1E6", "\u0001"]),
+            ("\U0001F1E6\u0308\u0001", &["\U0001F1E6\u0308", "\u0001"]), ("\U0001F1E6\u0300",
+            &["\U0001F1E6\u0300"]), ("\U0001F1E6\u0308\u0300", &["\U0001F1E6\u0308\u0300"]),
+            ("\U0001F1E6\u1100", &["\U0001F1E6", "\u1100"]), ("\U0001F1E6\u0308\u1100",
+            &["\U0001F1E6\u0308", "\u1100"]), ("\U0001F1E6\u1160", &["\U0001F1E6", "\u1160"]),
+            ("\U0001F1E6\u0308\u1160", &["\U0001F1E6\u0308", "\u1160"]), ("\U0001F1E6\u11A8",
+            &["\U0001F1E6", "\u11A8"]), ("\U0001F1E6\u0308\u11A8", &["\U0001F1E6\u0308",
+            "\u11A8"]), ("\U0001F1E6\uAC00", &["\U0001F1E6", "\uAC00"]),
+            ("\U0001F1E6\u0308\uAC00", &["\U0001F1E6\u0308", "\uAC00"]), ("\U0001F1E6\uAC01",
+            &["\U0001F1E6", "\uAC01"]), ("\U0001F1E6\u0308\uAC01", &["\U0001F1E6\u0308",
+            "\uAC01"]), ("\U0001F1E6\U0001F1E6", &["\U0001F1E6\U0001F1E6"]),
+            ("\U0001F1E6\u0308\U0001F1E6", &["\U0001F1E6\u0308", "\U0001F1E6"]),
+            ("\U0001F1E6\u0378", &["\U0001F1E6", "\u0378"]), ("\U0001F1E6\u0308\u0378",
+            &["\U0001F1E6\u0308", "\u0378"]), ("\u0378\u0020", &["\u0378", "\u0020"]),
+            ("\u0378\u0308\u0020", &["\u0378\u0308", "\u0020"]), ("\u0378\u000D", &["\u0378",
+            "\u000D"]), ("\u0378\u0308\u000D", &["\u0378\u0308", "\u000D"]), ("\u0378\u000A",
+            &["\u0378", "\u000A"]), ("\u0378\u0308\u000A", &["\u0378\u0308", "\u000A"]),
+            ("\u0378\u0001", &["\u0378", "\u0001"]), ("\u0378\u0308\u0001", &["\u0378\u0308",
+            "\u0001"]), ("\u0378\u0300", &["\u0378\u0300"]), ("\u0378\u0308\u0300",
+            &["\u0378\u0308\u0300"]), ("\u0378\u1100", &["\u0378", "\u1100"]),
+            ("\u0378\u0308\u1100", &["\u0378\u0308", "\u1100"]), ("\u0378\u1160", &["\u0378",
+            "\u1160"]), ("\u0378\u0308\u1160", &["\u0378\u0308", "\u1160"]), ("\u0378\u11A8",
+            &["\u0378", "\u11A8"]), ("\u0378\u0308\u11A8", &["\u0378\u0308", "\u11A8"]),
+            ("\u0378\uAC00", &["\u0378", "\uAC00"]), ("\u0378\u0308\uAC00", &["\u0378\u0308",
+            "\uAC00"]), ("\u0378\uAC01", &["\u0378", "\uAC01"]), ("\u0378\u0308\uAC01",
+            &["\u0378\u0308", "\uAC01"]), ("\u0378\U0001F1E6", &["\u0378", "\U0001F1E6"]),
+            ("\u0378\u0308\U0001F1E6", &["\u0378\u0308", "\U0001F1E6"]), ("\u0378\u0378",
+            &["\u0378", "\u0378"]), ("\u0378\u0308\u0378", &["\u0378\u0308", "\u0378"]),
+            ("\u0061\U0001F1E6\u0062", &["\u0061", "\U0001F1E6", "\u0062"]),
+            ("\U0001F1F7\U0001F1FA", &["\U0001F1F7\U0001F1FA"]),
+            ("\U0001F1F7\U0001F1FA\U0001F1F8", &["\U0001F1F7\U0001F1FA\U0001F1F8"]),
+            ("\U0001F1F7\U0001F1FA\U0001F1F8\U0001F1EA",
+            &["\U0001F1F7\U0001F1FA\U0001F1F8\U0001F1EA"]),
+            ("\U0001F1F7\U0001F1FA\u200B\U0001F1F8\U0001F1EA", &["\U0001F1F7\U0001F1FA", "\u200B",
+            "\U0001F1F8\U0001F1EA"]), ("\U0001F1E6\U0001F1E7\U0001F1E8",
+            &["\U0001F1E6\U0001F1E7\U0001F1E8"]), ("\U0001F1E6\u200D\U0001F1E7\U0001F1E8",
+            &["\U0001F1E6\u200D", "\U0001F1E7\U0001F1E8"]),
+            ("\U0001F1E6\U0001F1E7\u200D\U0001F1E8", &["\U0001F1E6\U0001F1E7\u200D",
+            "\U0001F1E8"]), ("\u0020\u200D\u0646", &["\u0020\u200D", "\u0646"]),
+            ("\u0646\u200D\u0020", &["\u0646\u200D", "\u0020"]),
+        ];
+
+        let test_diff = [
+            ("\u0020\u0903", &["\u0020\u0903"], &["\u0020", "\u0903"]), ("\u0020\u0308\u0903",
+            &["\u0020\u0308\u0903"], &["\u0020\u0308", "\u0903"]), ("\u000D\u0308\u0903",
+            &["\u000D", "\u0308\u0903"], &["\u000D", "\u0308", "\u0903"]), ("\u000A\u0308\u0903",
+            &["\u000A", "\u0308\u0903"], &["\u000A", "\u0308", "\u0903"]), ("\u0001\u0308\u0903",
+            &["\u0001", "\u0308\u0903"], &["\u0001", "\u0308", "\u0903"]), ("\u0300\u0903",
+            &["\u0300\u0903"], &["\u0300", "\u0903"]), ("\u0300\u0308\u0903",
+            &["\u0300\u0308\u0903"], &["\u0300\u0308", "\u0903"]), ("\u0903\u0903",
+            &["\u0903\u0903"], &["\u0903", "\u0903"]), ("\u0903\u0308\u0903",
+            &["\u0903\u0308\u0903"], &["\u0903\u0308", "\u0903"]), ("\u1100\u0903",
+            &["\u1100\u0903"], &["\u1100", "\u0903"]), ("\u1100\u0308\u0903",
+            &["\u1100\u0308\u0903"], &["\u1100\u0308", "\u0903"]), ("\u1160\u0903",
+            &["\u1160\u0903"], &["\u1160", "\u0903"]), ("\u1160\u0308\u0903",
+            &["\u1160\u0308\u0903"], &["\u1160\u0308", "\u0903"]), ("\u11A8\u0903",
+            &["\u11A8\u0903"], &["\u11A8", "\u0903"]), ("\u11A8\u0308\u0903",
+            &["\u11A8\u0308\u0903"], &["\u11A8\u0308", "\u0903"]), ("\uAC00\u0903",
+            &["\uAC00\u0903"], &["\uAC00", "\u0903"]), ("\uAC00\u0308\u0903",
+            &["\uAC00\u0308\u0903"], &["\uAC00\u0308", "\u0903"]), ("\uAC01\u0903",
+            &["\uAC01\u0903"], &["\uAC01", "\u0903"]), ("\uAC01\u0308\u0903",
+            &["\uAC01\u0308\u0903"], &["\uAC01\u0308", "\u0903"]), ("\U0001F1E6\u0903",
+            &["\U0001F1E6\u0903"], &["\U0001F1E6", "\u0903"]), ("\U0001F1E6\u0308\u0903",
+            &["\U0001F1E6\u0308\u0903"], &["\U0001F1E6\u0308", "\u0903"]), ("\u0378\u0903",
+            &["\u0378\u0903"], &["\u0378", "\u0903"]), ("\u0378\u0308\u0903",
+            &["\u0378\u0308\u0903"], &["\u0378\u0308", "\u0903"]),
+        ];
+
+        for &(s, g) in test_same.iter() {
+            // test forward iterator
+            assert!(order::equals(s.graphemes(true), g.iter().map(|&x| x)));
+            assert!(order::equals(s.graphemes(false), g.iter().map(|&x| x)));
+
+            // test reverse iterator
+            assert!(order::equals(s.graphemes(true).rev(), g.iter().rev().map(|&x| x)));
+            assert!(order::equals(s.graphemes(false).rev(), g.iter().rev().map(|&x| x)));
+        }
+
+        for &(s, gt, gf) in test_diff.iter() {
+            // test forward iterator
+            assert!(order::equals(s.graphemes(true), gt.iter().map(|&x| x)));
+            assert!(order::equals(s.graphemes(false), gf.iter().map(|&x| x)));
+
+            // test reverse iterator
+            assert!(order::equals(s.graphemes(true).rev(), gt.iter().rev().map(|&x| x)));
+            assert!(order::equals(s.graphemes(false).rev(), gf.iter().rev().map(|&x| x)));
+        }
+
+        // test the indices iterators
+        let s = "a̐éö̲\r\n";
+        let gr_inds = s.grapheme_indices(true).collect::<Vec<(uint, &str)>>();
+        assert_eq!(gr_inds.as_slice(), &[(0u, "a̐"), (3, "é"), (6, "ö̲"), (11, "\r\n")]);
+        let gr_inds = s.grapheme_indices(true).rev().collect::<Vec<(uint, &str)>>();
+        assert_eq!(gr_inds.as_slice(), &[(11, "\r\n"), (6, "ö̲"), (3, "é"), (0u, "a̐")]);
+        let mut gr_inds = s.grapheme_indices(true);
+        let e1 = gr_inds.size_hint();
+        assert_eq!(e1, (1, Some(13)));
+        let c = gr_inds.count();
+        assert_eq!(c, 4);
+        let e2 = gr_inds.size_hint();
+        assert_eq!(e2, (0, Some(0)));
+
+        // make sure the reverse iterator does the right thing with "\n" at beginning of string
+        let s = "\n\r\n\r";
+        let gr = s.graphemes(true).rev().collect::<Vec<&str>>();
+        assert_eq!(gr.as_slice(), &["\r", "\r\n", "\n"]);
+    }
+
+    #[test]
     fn test_split_strator() {
         fn t(s: &str, sep: &str, u: &[&str]) {
             let v: Vec<&str> = s.split_str(sep).collect();