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-rw-r--r--src/libextra/priority_queue.rs388
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diff --git a/src/libextra/priority_queue.rs b/src/libextra/priority_queue.rs
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-// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-//! A priority queue implemented with a binary heap
-
-#[allow(missing_doc)];
-
-use std::clone::Clone;
-use std::unstable::intrinsics::{move_val_init, init};
-use std::util::{replace, swap};
-use std::vec;
-
-/// A priority queue implemented with a binary heap
-#[deriving(Clone)]
-pub struct PriorityQueue<T> {
-    priv data: ~[T],
-}
-
-impl<T:Ord> Container for PriorityQueue<T> {
-    /// Returns the length of the queue
-    fn len(&self) -> uint { self.data.len() }
-}
-
-impl<T:Ord> Mutable for PriorityQueue<T> {
-    /// Drop all items from the queue
-    fn clear(&mut self) { self.data.truncate(0) }
-}
-
-impl<T:Ord> PriorityQueue<T> {
-    /// An iterator visiting all values in underlying vector, in
-    /// arbitrary order.
-    pub fn iter<'a>(&'a self) -> Items<'a, T> {
-        Items { iter: self.data.iter() }
-    }
-
-    /// Returns the greatest item in the queue - fails if empty
-    pub fn top<'a>(&'a self) -> &'a T { &self.data[0] }
-
-    /// Returns the greatest item in the queue - None if empty
-    pub fn maybe_top<'a>(&'a self) -> Option<&'a T> {
-        if self.is_empty() { None } else { Some(self.top()) }
-    }
-
-    /// Returns the number of elements the queue can hold without reallocating
-    pub fn capacity(&self) -> uint { self.data.capacity() }
-
-    /// Reserve capacity for exactly n elements in the PriorityQueue.
-    /// Do nothing if the capacity is already sufficient.
-    pub fn reserve_exact(&mut self, n: uint) { self.data.reserve_exact(n) }
-
-    /// Reserve capacity for at least n elements in the PriorityQueue.
-    /// Do nothing if the capacity is already sufficient.
-    pub fn reserve(&mut self, n: uint) {
-        self.data.reserve(n)
-    }
-
-    /// Pop the greatest item from the queue - fails if empty
-    pub fn pop(&mut self) -> T {
-        let mut item = self.data.pop().unwrap();
-        if !self.is_empty() {
-            swap(&mut item, &mut self.data[0]);
-            self.siftdown(0);
-        }
-        item
-    }
-
-    /// Pop the greatest item from the queue - None if empty
-    pub fn maybe_pop(&mut self) -> Option<T> {
-        if self.is_empty() { None } else { Some(self.pop()) }
-    }
-
-    /// Push an item onto the queue
-    pub fn push(&mut self, item: T) {
-        self.data.push(item);
-        let new_len = self.len() - 1;
-        self.siftup(0, new_len);
-    }
-
-    /// Optimized version of a push followed by a pop
-    pub fn push_pop(&mut self, mut item: T) -> T {
-        if !self.is_empty() && self.data[0] > item {
-            swap(&mut item, &mut self.data[0]);
-            self.siftdown(0);
-        }
-        item
-    }
-
-    /// Optimized version of a pop followed by a push - fails if empty
-    pub fn replace(&mut self, mut item: T) -> T {
-        swap(&mut item, &mut self.data[0]);
-        self.siftdown(0);
-        item
-    }
-
-    /// Consume the PriorityQueue and return the underlying vector
-    pub fn to_vec(self) -> ~[T] { let PriorityQueue{data: v} = self; v }
-
-    /// Consume the PriorityQueue and return a vector in sorted
-    /// (ascending) order
-    pub fn to_sorted_vec(self) -> ~[T] {
-        let mut q = self;
-        let mut end = q.len();
-        while end > 1 {
-            end -= 1;
-            q.data.swap(0, end);
-            q.siftdown_range(0, end)
-        }
-        q.to_vec()
-    }
-
-    /// Create an empty PriorityQueue
-    pub fn new() -> PriorityQueue<T> { PriorityQueue{data: ~[],} }
-
-    /// Create a PriorityQueue from a vector (heapify)
-    pub fn from_vec(xs: ~[T]) -> PriorityQueue<T> {
-        let mut q = PriorityQueue{data: xs,};
-        let mut n = q.len() / 2;
-        while n > 0 {
-            n -= 1;
-            q.siftdown(n)
-        }
-        q
-    }
-
-    // The implementations of siftup and siftdown use unsafe blocks in
-    // order to move an element out of the vector (leaving behind a
-    // zeroed element), shift along the others and move it back into the
-    // vector over the junk element.  This reduces the constant factor
-    // compared to using swaps, which involves twice as many moves.
-    fn siftup(&mut self, start: uint, mut pos: uint) {
-        unsafe {
-            let new = replace(&mut self.data[pos], init());
-
-            while pos > start {
-                let parent = (pos - 1) >> 1;
-                if new > self.data[parent] {
-                    let x = replace(&mut self.data[parent], init());
-                    move_val_init(&mut self.data[pos], x);
-                    pos = parent;
-                    continue
-                }
-                break
-            }
-            move_val_init(&mut self.data[pos], new);
-        }
-    }
-
-    fn siftdown_range(&mut self, mut pos: uint, end: uint) {
-        unsafe {
-            let start = pos;
-            let new = replace(&mut self.data[pos], init());
-
-            let mut child = 2 * pos + 1;
-            while child < end {
-                let right = child + 1;
-                if right < end && !(self.data[child] > self.data[right]) {
-                    child = right;
-                }
-                let x = replace(&mut self.data[child], init());
-                move_val_init(&mut self.data[pos], x);
-                pos = child;
-                child = 2 * pos + 1;
-            }
-
-            move_val_init(&mut self.data[pos], new);
-            self.siftup(start, pos);
-        }
-    }
-
-    fn siftdown(&mut self, pos: uint) {
-        let len = self.len();
-        self.siftdown_range(pos, len);
-    }
-}
-
-/// PriorityQueue iterator
-pub struct Items <'a, T> {
-    priv iter: vec::Items<'a, T>,
-}
-
-impl<'a, T> Iterator<&'a T> for Items<'a, T> {
-    #[inline]
-    fn next(&mut self) -> Option<(&'a T)> { self.iter.next() }
-
-    #[inline]
-    fn size_hint(&self) -> (uint, Option<uint>) { self.iter.size_hint() }
-}
-
-impl<T: Ord> FromIterator<T> for PriorityQueue<T> {
-    fn from_iterator<Iter: Iterator<T>>(iter: &mut Iter) -> PriorityQueue<T> {
-        let mut q = PriorityQueue::new();
-        q.extend(iter);
-
-        q
-    }
-}
-
-impl<T: Ord> Extendable<T> for PriorityQueue<T> {
-    fn extend<Iter: Iterator<T>>(&mut self, iter: &mut Iter) {
-        let (lower, _) = iter.size_hint();
-
-        let len = self.capacity();
-        self.reserve(len + lower);
-
-        for elem in *iter {
-            self.push(elem);
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use priority_queue::PriorityQueue;
-
-    #[test]
-    fn test_iterator() {
-        let data = ~[5, 9, 3];
-        let iterout = ~[9, 5, 3];
-        let pq = PriorityQueue::from_vec(data);
-        let mut i = 0;
-        for el in pq.iter() {
-            assert_eq!(*el, iterout[i]);
-            i += 1;
-        }
-    }
-
-    #[test]
-    fn test_top_and_pop() {
-        let data = ~[2u, 4, 6, 2, 1, 8, 10, 3, 5, 7, 0, 9, 1];
-        let mut sorted = data.clone();
-        sorted.sort();
-        let mut heap = PriorityQueue::from_vec(data);
-        while !heap.is_empty() {
-            assert_eq!(heap.top(), sorted.last().unwrap());
-            assert_eq!(heap.pop(), sorted.pop().unwrap());
-        }
-    }
-
-    #[test]
-    fn test_push() {
-        let mut heap = PriorityQueue::from_vec(~[2, 4, 9]);
-        assert_eq!(heap.len(), 3);
-        assert!(*heap.top() == 9);
-        heap.push(11);
-        assert_eq!(heap.len(), 4);
-        assert!(*heap.top() == 11);
-        heap.push(5);
-        assert_eq!(heap.len(), 5);
-        assert!(*heap.top() == 11);
-        heap.push(27);
-        assert_eq!(heap.len(), 6);
-        assert!(*heap.top() == 27);
-        heap.push(3);
-        assert_eq!(heap.len(), 7);
-        assert!(*heap.top() == 27);
-        heap.push(103);
-        assert_eq!(heap.len(), 8);
-        assert!(*heap.top() == 103);
-    }
-
-    #[test]
-    fn test_push_unique() {
-        let mut heap = PriorityQueue::from_vec(~[~2, ~4, ~9]);
-        assert_eq!(heap.len(), 3);
-        assert!(*heap.top() == ~9);
-        heap.push(~11);
-        assert_eq!(heap.len(), 4);
-        assert!(*heap.top() == ~11);
-        heap.push(~5);
-        assert_eq!(heap.len(), 5);
-        assert!(*heap.top() == ~11);
-        heap.push(~27);
-        assert_eq!(heap.len(), 6);
-        assert!(*heap.top() == ~27);
-        heap.push(~3);
-        assert_eq!(heap.len(), 7);
-        assert!(*heap.top() == ~27);
-        heap.push(~103);
-        assert_eq!(heap.len(), 8);
-        assert!(*heap.top() == ~103);
-    }
-
-    #[test]
-    fn test_push_pop() {
-        let mut heap = PriorityQueue::from_vec(~[5, 5, 2, 1, 3]);
-        assert_eq!(heap.len(), 5);
-        assert_eq!(heap.push_pop(6), 6);
-        assert_eq!(heap.len(), 5);
-        assert_eq!(heap.push_pop(0), 5);
-        assert_eq!(heap.len(), 5);
-        assert_eq!(heap.push_pop(4), 5);
-        assert_eq!(heap.len(), 5);
-        assert_eq!(heap.push_pop(1), 4);
-        assert_eq!(heap.len(), 5);
-    }
-
-    #[test]
-    fn test_replace() {
-        let mut heap = PriorityQueue::from_vec(~[5, 5, 2, 1, 3]);
-        assert_eq!(heap.len(), 5);
-        assert_eq!(heap.replace(6), 5);
-        assert_eq!(heap.len(), 5);
-        assert_eq!(heap.replace(0), 6);
-        assert_eq!(heap.len(), 5);
-        assert_eq!(heap.replace(4), 5);
-        assert_eq!(heap.len(), 5);
-        assert_eq!(heap.replace(1), 4);
-        assert_eq!(heap.len(), 5);
-    }
-
-    fn check_to_vec(mut data: ~[int]) {
-        let heap = PriorityQueue::from_vec(data.clone());
-        let mut v = heap.clone().to_vec();
-        v.sort();
-        data.sort();
-
-        assert_eq!(v, data);
-        assert_eq!(heap.to_sorted_vec(), data);
-    }
-
-    #[test]
-    fn test_to_vec() {
-        check_to_vec(~[]);
-        check_to_vec(~[5]);
-        check_to_vec(~[3, 2]);
-        check_to_vec(~[2, 3]);
-        check_to_vec(~[5, 1, 2]);
-        check_to_vec(~[1, 100, 2, 3]);
-        check_to_vec(~[1, 3, 5, 7, 9, 2, 4, 6, 8, 0]);
-        check_to_vec(~[2, 4, 6, 2, 1, 8, 10, 3, 5, 7, 0, 9, 1]);
-        check_to_vec(~[9, 11, 9, 9, 9, 9, 11, 2, 3, 4, 11, 9, 0, 0, 0, 0]);
-        check_to_vec(~[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
-        check_to_vec(~[10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0]);
-        check_to_vec(~[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 0, 0, 1, 2]);
-        check_to_vec(~[5, 4, 3, 2, 1, 5, 4, 3, 2, 1, 5, 4, 3, 2, 1]);
-    }
-
-    #[test]
-    #[should_fail]
-    fn test_empty_pop() {
-        let mut heap: PriorityQueue<int> = PriorityQueue::new();
-        heap.pop();
-    }
-
-    #[test]
-    fn test_empty_maybe_pop() {
-        let mut heap: PriorityQueue<int> = PriorityQueue::new();
-        assert!(heap.maybe_pop().is_none());
-    }
-
-    #[test]
-    #[should_fail]
-    fn test_empty_top() {
-        let empty: PriorityQueue<int> = PriorityQueue::new();
-        empty.top();
-    }
-
-    #[test]
-    fn test_empty_maybe_top() {
-        let empty: PriorityQueue<int> = PriorityQueue::new();
-        assert!(empty.maybe_top().is_none());
-    }
-
-    #[test]
-    #[should_fail]
-    fn test_empty_replace() {
-        let mut heap: PriorityQueue<int> = PriorityQueue::new();
-        heap.replace(5);
-    }
-
-    #[test]
-    fn test_from_iter() {
-        let xs = ~[9u, 8, 7, 6, 5, 4, 3, 2, 1];
-
-        let mut q: PriorityQueue<uint> = xs.rev_iter().map(|&x| x).collect();
-
-        for &x in xs.iter() {
-            assert_eq!(q.pop(), x);
-        }
-    }
-}