From 167b510b7c59ad4d87993059401b94a5e1d1f8ff Mon Sep 17 00:00:00 2001
From: Andrea Canciani <ranma42@gmail.com>
Date: Mon, 18 Jan 2016 17:46:53 +0100
Subject: [PATCH 1/2] Implement `last` for `EscapeUnicode`

Part of #24214.
---
 src/libcore/char.rs | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/libcore/char.rs b/src/libcore/char.rs
index 140403884b96d..65b9a27bb68e2 100644
--- a/src/libcore/char.rs
+++ b/src/libcore/char.rs
@@ -471,6 +471,18 @@ impl Iterator for EscapeUnicode {
         let n = n + self.hex_digit_idx;
         (n, Some(n))
     }
+
+    fn last(self) -> Option<char> {
+        match self.state {
+            EscapeUnicodeState::Done => None,
+
+            EscapeUnicodeState::RightBrace |
+            EscapeUnicodeState::Value |
+            EscapeUnicodeState::LeftBrace |
+            EscapeUnicodeState::Type |
+            EscapeUnicodeState::Backslash => Some('}'),
+        }
+    }
 }
 
 /// An iterator that yields the literal escape code of a `char`.

From 8169fa2fe84b6e3944f7362d3e73ba763a2da1d9 Mon Sep 17 00:00:00 2001
From: Andrea Canciani <ranma42@gmail.com>
Date: Wed, 4 May 2016 12:08:11 +0200
Subject: [PATCH 2/2] Add test for `EscapeUnicode` specializations

---
 src/libcoretest/char.rs | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/src/libcoretest/char.rs b/src/libcoretest/char.rs
index 41fd742c9e011..e959e71daf73f 100644
--- a/src/libcoretest/char.rs
+++ b/src/libcoretest/char.rs
@@ -262,4 +262,37 @@ fn ed_iterator_specializations() {
     assert_eq!('\''.escape_default().last(), Some('\''));
 }
 
+#[test]
+fn eu_iterator_specializations() {
+    fn check(c: char) {
+        let len = c.escape_unicode().count();
+
+        // Check OoB
+        assert_eq!(c.escape_unicode().nth(len), None);
+
+        // For all possible in-bound offsets
+        let mut iter = c.escape_unicode();
+        for offset in 0..len {
+            // Check last
+            assert_eq!(iter.clone().last(), Some('}'));
 
+            // Check counting
+            assert_eq!(iter.clone().count(), len - offset);
+
+            // Check nth
+            assert_eq!(c.escape_unicode().nth(offset), iter.next());
+        }
+
+        // Check post-last
+        assert_eq!(iter.clone().last(), None);
+        assert_eq!(iter.clone().count(), 0);
+    }
+
+    check('\u{0}');
+    check('\u{1}');
+    check('\u{12}');
+    check('\u{123}');
+    check('\u{1234}');
+    check('\u{12340}');
+    check('\u{10FFFF}');
+}