Implement `last` for `EscapeUnicode`

Part of #24214.

diff --git a/src/libcore/char.rs b/src/libcore/char.rs
index 140403884b96df89d8fbc5e470e2c0a574264c72..65b9a27bb68e2a47da6b7b375a125221d9de1f5a 100644 (file)
--- a/src/libcore/char.rs
+++ b/src/libcore/char.rs
@@ -471,6 +471,18 @@ fn size_hint(&self) -> (usize, Option<usize>) {
         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`.