diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/libcollections/vec.rs | 250 |
1 files changed, 124 insertions, 126 deletions
diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs index efbabb5a6f4..bf9c2ae49a0 100644 --- a/src/libcollections/vec.rs +++ b/src/libcollections/vec.rs @@ -782,6 +782,130 @@ impl<T> Vec<T> { } } + /// Removes consecutive elements in the vector that resolve to the same key. + /// + /// If the vector is sorted, this removes all duplicates. + /// + /// # Examples + /// + /// ``` + /// #![feature(dedup_by)] + /// + /// let mut vec = vec![10, 20, 21, 30, 20]; + /// + /// vec.dedup_by_key(|i| *i / 10); + /// + /// assert_eq!(vec, [10, 20, 30, 20]); + /// ``` + #[unstable(feature = "dedup_by", reason = "recently added", issue = "37087")] + #[inline] + pub fn dedup_by_key<F, K>(&mut self, mut key: F) where F: FnMut(&mut T) -> K, K: PartialEq { + self.dedup_by(|a, b| key(a) == key(b)) + } + + /// Removes consecutive elements in the vector that resolve to the same key. + /// + /// If the vector is sorted, this removes all duplicates. + /// + /// # Examples + /// + /// ``` + /// #![feature(dedup_by)] + /// use std::ascii::AsciiExt; + /// + /// let mut vec = vec!["foo", "bar", "Bar", "baz", "bar"]; + /// + /// vec.dedup_by(|a, b| a.eq_ignore_ascii_case(b)); + /// + /// assert_eq!(vec, ["foo", "bar", "baz", "bar"]); + /// ``` + #[unstable(feature = "dedup_by", reason = "recently added", issue = "37087")] + pub fn dedup_by<F>(&mut self, mut same_bucket: F) where F: FnMut(&mut T, &mut T) -> bool { + unsafe { + // Although we have a mutable reference to `self`, we cannot make + // *arbitrary* changes. The `PartialEq` comparisons could panic, so we + // must ensure that the vector is in a valid state at all time. + // + // The way that we handle this is by using swaps; we iterate + // over all the elements, swapping as we go so that at the end + // the elements we wish to keep are in the front, and those we + // wish to reject are at the back. We can then truncate the + // vector. This operation is still O(n). + // + // Example: We start in this state, where `r` represents "next + // read" and `w` represents "next_write`. + // + // r + // +---+---+---+---+---+---+ + // | 0 | 1 | 1 | 2 | 3 | 3 | + // +---+---+---+---+---+---+ + // w + // + // Comparing self[r] against self[w-1], this is not a duplicate, so + // we swap self[r] and self[w] (no effect as r==w) and then increment both + // r and w, leaving us with: + // + // r + // +---+---+---+---+---+---+ + // | 0 | 1 | 1 | 2 | 3 | 3 | + // +---+---+---+---+---+---+ + // w + // + // Comparing self[r] against self[w-1], this value is a duplicate, + // so we increment `r` but leave everything else unchanged: + // + // r + // +---+---+---+---+---+---+ + // | 0 | 1 | 1 | 2 | 3 | 3 | + // +---+---+---+---+---+---+ + // w + // + // Comparing self[r] against self[w-1], this is not a duplicate, + // so swap self[r] and self[w] and advance r and w: + // + // r + // +---+---+---+---+---+---+ + // | 0 | 1 | 2 | 1 | 3 | 3 | + // +---+---+---+---+---+---+ + // w + // + // Not a duplicate, repeat: + // + // r + // +---+---+---+---+---+---+ + // | 0 | 1 | 2 | 3 | 1 | 3 | + // +---+---+---+---+---+---+ + // w + // + // Duplicate, advance r. End of vec. Truncate to w. + + let ln = self.len(); + if ln <= 1 { + return; + } + + // Avoid bounds checks by using raw pointers. + let p = self.as_mut_ptr(); + let mut r: usize = 1; + let mut w: usize = 1; + + while r < ln { + let p_r = p.offset(r as isize); + let p_wm1 = p.offset((w - 1) as isize); + if !same_bucket(&mut *p_r, &mut *p_wm1) { + if r != w { + let p_w = p_wm1.offset(1); + mem::swap(&mut *p_r, &mut *p_w); + } + w += 1; + } + r += 1; + } + + self.truncate(w); + } + } + /// Appends an element to the back of a collection. /// /// # Panics @@ -1162,132 +1286,6 @@ impl<T: PartialEq> Vec<T> { } } -impl<T> Vec<T> { - /// Removes consecutive elements in the vector that resolve to the same key. - /// - /// If the vector is sorted, this removes all duplicates. - /// - /// # Examples - /// - /// ``` - /// #![feature(dedup_by)] - /// - /// let mut vec = vec![10, 20, 21, 30, 20]; - /// - /// vec.dedup_by_key(|i| *i / 10); - /// - /// assert_eq!(vec, [10, 20, 30, 20]); - /// ``` - #[unstable(feature = "dedup_by", reason = "recently added", issue = "37087")] - #[inline] - pub fn dedup_by_key<F, K>(&mut self, mut key: F) where F: FnMut(&mut T) -> K, K: PartialEq { - self.dedup_by(|a, b| key(a) == key(b)) - } - - /// Removes consecutive elements in the vector that resolve to the same key. - /// - /// If the vector is sorted, this removes all duplicates. - /// - /// # Examples - /// - /// ``` - /// #![feature(dedup_by)] - /// use std::ascii::AsciiExt; - /// - /// let mut vec = vec!["foo", "bar", "Bar", "baz", "bar"]; - /// - /// vec.dedup_by(|a, b| a.eq_ignore_ascii_case(b)); - /// - /// assert_eq!(vec, ["foo", "bar", "baz", "bar"]); - /// ``` - #[unstable(feature = "dedup_by", reason = "recently added", issue = "37087")] - pub fn dedup_by<F>(&mut self, mut same_bucket: F) where F: FnMut(&mut T, &mut T) -> bool { - unsafe { - // Although we have a mutable reference to `self`, we cannot make - // *arbitrary* changes. The `PartialEq` comparisons could panic, so we - // must ensure that the vector is in a valid state at all time. - // - // The way that we handle this is by using swaps; we iterate - // over all the elements, swapping as we go so that at the end - // the elements we wish to keep are in the front, and those we - // wish to reject are at the back. We can then truncate the - // vector. This operation is still O(n). - // - // Example: We start in this state, where `r` represents "next - // read" and `w` represents "next_write`. - // - // r - // +---+---+---+---+---+---+ - // | 0 | 1 | 1 | 2 | 3 | 3 | - // +---+---+---+---+---+---+ - // w - // - // Comparing self[r] against self[w-1], this is not a duplicate, so - // we swap self[r] and self[w] (no effect as r==w) and then increment both - // r and w, leaving us with: - // - // r - // +---+---+---+---+---+---+ - // | 0 | 1 | 1 | 2 | 3 | 3 | - // +---+---+---+---+---+---+ - // w - // - // Comparing self[r] against self[w-1], this value is a duplicate, - // so we increment `r` but leave everything else unchanged: - // - // r - // +---+---+---+---+---+---+ - // | 0 | 1 | 1 | 2 | 3 | 3 | - // +---+---+---+---+---+---+ - // w - // - // Comparing self[r] against self[w-1], this is not a duplicate, - // so swap self[r] and self[w] and advance r and w: - // - // r - // +---+---+---+---+---+---+ - // | 0 | 1 | 2 | 1 | 3 | 3 | - // +---+---+---+---+---+---+ - // w - // - // Not a duplicate, repeat: - // - // r - // +---+---+---+---+---+---+ - // | 0 | 1 | 2 | 3 | 1 | 3 | - // +---+---+---+---+---+---+ - // w - // - // Duplicate, advance r. End of vec. Truncate to w. - - let ln = self.len(); - if ln <= 1 { - return; - } - - // Avoid bounds checks by using raw pointers. - let p = self.as_mut_ptr(); - let mut r: usize = 1; - let mut w: usize = 1; - - while r < ln { - let p_r = p.offset(r as isize); - let p_wm1 = p.offset((w - 1) as isize); - if !same_bucket(&mut *p_r, &mut *p_wm1) { - if r != w { - let p_w = p_wm1.offset(1); - mem::swap(&mut *p_r, &mut *p_w); - } - w += 1; - } - r += 1; - } - - self.truncate(w); - } - } -} - //////////////////////////////////////////////////////////////////////////////// // Internal methods and functions //////////////////////////////////////////////////////////////////////////////// |