auto merge of #11061 : huonw/rust/opt-unsafe-vec, r=alexcrichton
Before: ``` test vec::bench::random_inserts ... bench: 15025 ns/iter (+/- 409) test vec::bench::random_removes ... bench: 16063 ns/iter (+/- 276) ``` After: ``` test vec::bench::random_inserts ... bench: 5257 ns/iter (+/- 321) test vec::bench::random_removes ... bench: 4980 ns/iter (+/- 94) ```
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@ -1400,6 +1400,22 @@ pub trait OwnedVector<T> {
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/// elements after position i one position to the right.
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fn insert(&mut self, i: uint, x:T);
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/// Remove and return the element at position `i` within `v`,
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/// shifting all elements after position `i` one position to the
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/// left. Returns `None` if `i` is out of bounds.
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///
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/// # Example
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/// ```rust
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/// let mut v = ~[1, 2, 3];
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/// assert_eq!(v.remove_opt(1), Some(2));
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/// assert_eq!(v, ~[1, 3]);
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///
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/// assert_eq!(v.remove_opt(4), None);
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/// // v is unchanged:
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/// assert_eq!(v, ~[1, 3]);
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/// ```
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fn remove_opt(&mut self, i: uint) -> Option<T>;
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/// Remove and return the element at position i within v, shifting
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/// all elements after position i one position to the left.
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fn remove(&mut self, i: uint) -> T;
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@ -1609,66 +1625,59 @@ impl<T> OwnedVector<T> for ~[T] {
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}
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fn shift_opt(&mut self) -> Option<T> {
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match self.len() {
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0 => None,
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1 => self.pop_opt(),
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2 => {
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let last = self.pop();
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let first = self.pop_opt();
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self.push(last);
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first
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}
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len => {
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unsafe {
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let next_len = len - 1;
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let ptr = self.as_ptr();
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// copy out the head element, for the moment it exists
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// unsafely on the stack and as the first element of the
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// vector.
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let head = ptr::read_ptr(ptr);
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// Memcpy everything to the left one element (leaving the
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// last element unsafely in two consecutive memory
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// locations)
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ptr::copy_memory(self.as_mut_ptr(), ptr.offset(1), next_len);
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// set the new length, which means the second instance of
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// the last element is forgotten.
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self.set_len(next_len);
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Some(head)
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}
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}
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}
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self.remove_opt(0)
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}
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fn unshift(&mut self, x: T) {
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let v = util::replace(self, ~[x]);
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self.push_all_move(v);
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self.insert(0, x)
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}
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fn insert(&mut self, i: uint, x:T) {
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fn insert(&mut self, i: uint, x: T) {
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let len = self.len();
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assert!(i <= len);
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// space for the new element
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self.reserve_additional(1);
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self.push(x);
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let mut j = len;
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while j > i {
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self.swap(j, j - 1);
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j -= 1;
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unsafe { // infallible
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// The spot to put the new value
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let p = self.as_mut_ptr().offset(i as int);
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// Shift everything over to make space. (Duplicating the
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// `i`th element into two consecutive places.)
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ptr::copy_memory(p.offset(1), p, len - i);
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// Write it in, overwriting the first copy of the `i`th
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// element.
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intrinsics::move_val_init(&mut *p, x);
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self.set_len(len + 1);
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}
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}
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fn remove(&mut self, i: uint) -> T {
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let len = self.len();
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assert!(i < len);
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let mut j = i;
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while j < len - 1 {
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self.swap(j, j + 1);
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j += 1;
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#[inline]
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fn remove(&mut self, i: uint) -> T {
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match self.remove_opt(i) {
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Some(t) => t,
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None => fail!("remove: the len is {} but the index is {}", self.len(), i)
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}
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}
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fn remove_opt(&mut self, i: uint) -> Option<T> {
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let len = self.len();
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if i < len {
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unsafe { // infallible
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// the place we are taking from.
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let ptr = self.as_mut_ptr().offset(i as int);
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// copy it out, unsafely having a copy of the value on
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// the stack and in the vector at the same time.
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let ret = Some(ptr::read_ptr(ptr as *T));
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// Shift everything down to fill in that spot.
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ptr::copy_memory(ptr, ptr.offset(1), len - i - 1);
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self.set_len(len - 1);
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ret
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}
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} else {
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None
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}
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self.pop()
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}
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fn swap_remove(&mut self, index: uint) -> T {
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let ln = self.len();
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@ -3380,6 +3389,29 @@ mod tests {
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a.insert(4, 5);
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}
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#[test]
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fn test_remove_opt() {
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let mut a = ~[1,2,3,4];
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assert_eq!(a.remove_opt(2), Some(3));
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assert_eq!(a, ~[1,2,4]);
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assert_eq!(a.remove_opt(2), Some(4));
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assert_eq!(a, ~[1,2]);
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assert_eq!(a.remove_opt(2), None);
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assert_eq!(a, ~[1,2]);
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assert_eq!(a.remove_opt(0), Some(1));
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assert_eq!(a, ~[2]);
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assert_eq!(a.remove_opt(0), Some(2));
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assert_eq!(a, ~[]);
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assert_eq!(a.remove_opt(0), None);
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assert_eq!(a.remove_opt(10), None);
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}
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#[test]
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fn test_remove() {
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let mut a = ~[1, 2, 3, 4];
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@ -4092,6 +4124,7 @@ mod bench {
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use vec::VectorVector;
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use option::*;
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use ptr;
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use rand::{weak_rng, Rng};
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#[bench]
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fn iterator(bh: &mut BenchHarness) {
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@ -4268,4 +4301,28 @@ mod bench {
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}
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});
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}
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#[bench]
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fn random_inserts(bh: &mut BenchHarness) {
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let mut rng = weak_rng();
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bh.iter(|| {
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let mut v = vec::from_elem(30, (0u, 0u));
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for _ in range(0, 100) {
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let l = v.len();
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v.insert(rng.gen::<uint>() % (l + 1),
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(1, 1));
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}
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})
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}
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#[bench]
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fn random_removes(bh: &mut BenchHarness) {
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let mut rng = weak_rng();
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bh.iter(|| {
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let mut v = vec::from_elem(130, (0u, 0u));
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for _ in range(0, 100) {
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let l = v.len();
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v.remove(rng.gen::<uint>() % l);
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}
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})
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}
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}
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