Auto merge of #33103 - ranma42:escape-unicode-last, r=alexcrichton

Implement `last` for `EscapeUnicode`

The implementation is quite trivial as the last character is always `'{'`.
As a side-effect it also improves the implementation of `last` for `EscapeUnicode`.

Part of #24214, split from #31049.

Maybe this (and the other changes that I will split from #31049) should wait for a test like `ed_iterator_specializations` to be added. Would it be sufficient to do the same for each possible escape length?

1 files changed, 12 insertions, 0 deletions

diff --git a/src/libcore/char.rs b/src/libcore/char.rs
index 140403884b9..65b9a27bb68 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`.