diff --git a/src/libcollections/str.rs b/src/libcollections/str.rs index 3a289e4ef3738..6379155800b17 100644 --- a/src/libcollections/str.rs +++ b/src/libcollections/str.rs @@ -74,8 +74,8 @@ use slice::SliceConcatExt; pub use core::str::{FromStr, Utf8Error, Str}; pub use core::str::{Lines, LinesAny, MatchIndices, SplitStr, CharRange}; -pub use core::str::{Split, SplitTerminator}; -pub use core::str::{SplitN, RSplitN}; +pub use core::str::{Split, SplitTerminator, SplitN}; +pub use core::str::{RSplit, RSplitN}; pub use core::str::{from_utf8, CharEq, Chars, CharIndices, Bytes}; pub use core::str::{from_utf8_unchecked, from_c_str, ParseBoolError}; pub use unicode::str::{Words, Graphemes, GraphemeIndices}; @@ -699,6 +699,34 @@ impl str { core_str::StrExt::split_terminator(&self[..], pat) } + /// An iterator over substrings of `self`, separated by a pattern, + /// starting from the end of the string. + /// + /// # Examples + /// + /// Simple patterns: + /// + /// ``` + /// let v: Vec<&str> = "Mary had a little lamb".rsplit(' ').collect(); + /// assert_eq!(v, ["lamb", "little", "a", "had", "Mary"]); + /// + /// let v: Vec<&str> = "lion::tiger::leopard".rsplit("::").collect(); + /// assert_eq!(v, ["leopard", "tiger", "lion"]); + /// ``` + /// + /// More complex patterns with a lambda: + /// + /// ``` + /// let v: Vec<&str> = "abc1def2ghi".rsplit(|c: char| c.is_numeric()).collect(); + /// assert_eq!(v, ["ghi", "def", "abc"]); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn rsplit<'a, P: Pattern<'a>>(&'a self, pat: P) -> RSplit<'a, P> + where P::Searcher: ReverseSearcher<'a> + { + core_str::StrExt::rsplit(&self[..], pat) + } + /// An iterator over substrings of `self`, separated by characters matched by a pattern, /// starting from the end of the string. /// diff --git a/src/libcollectionstest/str.rs b/src/libcollectionstest/str.rs index 79c2d719862a9..2498b27395a4c 100644 --- a/src/libcollectionstest/str.rs +++ b/src/libcollectionstest/str.rs @@ -910,6 +910,20 @@ fn test_split_char_iterator_no_trailing() { assert_eq!(split, ["", "Märy häd ä little lämb", "Little lämb"]); } +#[test] +fn test_rsplit() { + let data = "\nMäry häd ä little lämb\nLittle lämb\n"; + + let split: Vec<&str> = data.rsplit(' ').collect(); + assert_eq!(split, ["lämb\n", "lämb\nLittle", "little", "ä", "häd", "\nMäry"]); + + let split: Vec<&str> = data.rsplit("lämb").collect(); + assert_eq!(split, ["\n", "\nLittle ", "\nMäry häd ä little "]); + + let split: Vec<&str> = data.rsplit(|c: char| c == 'ä').collect(); + assert_eq!(split, ["mb\n", "mb\nLittle l", " little l", "d ", "ry h", "\nM"]); +} + #[test] fn test_words() { let data = "\n \tMäry häd\tä little lämb\nLittle lämb\n"; diff --git a/src/libcore/str/mod.rs b/src/libcore/str/mod.rs index e8181395b5c1e..fc2aa256f05f4 100644 --- a/src/libcore/str/mod.rs +++ b/src/libcore/str/mod.rs @@ -111,7 +111,24 @@ macro_rules! delegate_iter { self.0.size_hint() } } - } + }; + (pattern reverse $te:ty : $ti:ty) => { + #[stable(feature = "rust1", since = "1.0.0")] + impl<'a, P: Pattern<'a>> Iterator for $ti + where P::Searcher: ReverseSearcher<'a> + { + type Item = $te; + + #[inline] + fn next(&mut self) -> Option<$te> { + self.0.next() + } + #[inline] + fn size_hint(&self) -> (usize, Option) { + self.0.size_hint() + } + } + }; } /// A trait to abstract the idea of creating a new instance of a type from a @@ -553,6 +570,19 @@ struct CharSplitsN<'a, P: Pattern<'a>> { invert: bool, } +/// An iterator over the substrings of a string, separated by a +/// pattern, in reverse order. +struct RCharSplits<'a, P: Pattern<'a>> { + /// The slice remaining to be iterated + start: usize, + end: usize, + matcher: P::Searcher, + /// Whether an empty string at the end of iteration is allowed + allow_final_empty: bool, + finished: bool, +} + + /// An iterator over the lines of a string, separated by `\n`. #[stable(feature = "rust1", since = "1.0.0")] pub struct Lines<'a> { @@ -646,6 +676,43 @@ where P::Searcher: DoubleEndedSearcher<'a> { } } +impl<'a, P: Pattern<'a>> RCharSplits<'a, P> { + #[inline] + fn get_remainder(&mut self) -> Option<&'a str> { + if !self.finished && (self.allow_final_empty || self.end - self.start > 0) { + self.finished = true; + unsafe { + let string = self.matcher.haystack().slice_unchecked(self.start, self.end); + Some(string) + } + } else { + None + } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<'a, P: Pattern<'a>> Iterator for RCharSplits<'a, P> + where P::Searcher: ReverseSearcher<'a> +{ + type Item = &'a str; + + #[inline] + fn next(&mut self) -> Option<&'a str> { + if self.finished { return None } + + let haystack = self.matcher.haystack(); + match self.matcher.next_match_back() { + Some((a, b)) => unsafe { + let elt = haystack.slice_unchecked(b, self.end); + self.end = a; + Some(elt) + }, + None => self.get_remainder(), + } + } +} + /// The internal state of an iterator that searches for matches of a substring /// within a larger string using two-way search #[derive(Clone)] @@ -1321,6 +1388,11 @@ delegate_iter!{pattern &'a str : SplitTerminator<'a, P>} pub struct SplitN<'a, P: Pattern<'a>>(CharSplitsN<'a, P>); delegate_iter!{pattern forward &'a str : SplitN<'a, P>} +/// Return type of `StrExt::rsplit` +#[stable(feature = "rust1", since = "1.0.0")] +pub struct RSplit<'a, P: Pattern<'a>>(RCharSplits<'a, P>); +delegate_iter!{pattern reverse &'a str : RSplit<'a, P>} + /// Return type of `StrExt::rsplitn` #[stable(feature = "rust1", since = "1.0.0")] pub struct RSplitN<'a, P: Pattern<'a>>(CharSplitsN<'a, P>); @@ -1340,6 +1412,8 @@ pub trait StrExt { fn split<'a, P: Pattern<'a>>(&'a self, pat: P) -> Split<'a, P>; fn splitn<'a, P: Pattern<'a>>(&'a self, count: usize, pat: P) -> SplitN<'a, P>; fn split_terminator<'a, P: Pattern<'a>>(&'a self, pat: P) -> SplitTerminator<'a, P>; + fn rsplit<'a, P: Pattern<'a>>(&'a self, pat: P) -> RSplit<'a, P> + where P::Searcher: ReverseSearcher<'a>; fn rsplitn<'a, P: Pattern<'a>>(&'a self, count: usize, pat: P) -> RSplitN<'a, P>; fn match_indices<'a, P: Pattern<'a>>(&'a self, pat: P) -> MatchIndices<'a, P>; #[allow(deprecated) /* for SplitStr */] @@ -1436,6 +1510,19 @@ impl StrExt for str { }) } + #[inline] + fn rsplit<'a, P: Pattern<'a>>(&'a self, pat: P) -> RSplit<'a, P> + where P::Searcher: ReverseSearcher<'a> + { + RSplit(RCharSplits { + start: 0, + end: self.len(), + matcher: pat.into_searcher(self), + allow_final_empty: true, + finished: false, + }) + } + #[inline] fn rsplitn<'a, P: Pattern<'a>>(&'a self, count: usize, pat: P) -> RSplitN<'a, P> { RSplitN(CharSplitsN {