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 { + 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`. 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}'); +}