327 lines
9.8 KiB
Rust
327 lines
9.8 KiB
Rust
// 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
|
|
|
|
use core::container::{Container, Mutable};
|
|
use core::cmp::Ord;
|
|
use core::iter::BaseIter;
|
|
use core::prelude::*;
|
|
use core::ptr::addr_of;
|
|
use core::vec;
|
|
|
|
#[abi = "rust-intrinsic"]
|
|
extern "C" mod rusti {
|
|
fn move_val_init<T>(dst: &mut T, +src: T);
|
|
fn init<T>() -> T;
|
|
}
|
|
|
|
pub struct PriorityQueue<T> {
|
|
priv data: ~[T],
|
|
}
|
|
|
|
impl<T:Ord> BaseIter<T> for PriorityQueue<T> {
|
|
/// Visit all values in the underlying vector.
|
|
///
|
|
/// The values are **not** visited in order.
|
|
fn each(&self, f: &fn(&T) -> bool) { self.data.each(f) }
|
|
fn size_hint(&self) -> Option<uint> { self.data.size_hint() }
|
|
}
|
|
|
|
impl<T:Ord> Container for PriorityQueue<T> {
|
|
/// Returns the length of the queue
|
|
fn len(&const self) -> uint { vec::uniq_len(&const self.data) }
|
|
|
|
/// Returns true if a queue contains no elements
|
|
fn is_empty(&const self) -> bool { self.len() == 0 }
|
|
}
|
|
|
|
impl<T:Ord> Mutable for PriorityQueue<T> {
|
|
/// Drop all items from the queue
|
|
fn clear(&mut self) { self.data.truncate(0) }
|
|
}
|
|
|
|
pub impl <T:Ord> PriorityQueue<T> {
|
|
/// Returns the greatest item in the queue - fails if empty
|
|
fn top(&self) -> &'self T { &self.data[0] }
|
|
|
|
/// Returns the greatest item in the queue - None if empty
|
|
fn maybe_top(&self) -> Option<&'self T> {
|
|
if self.is_empty() { None } else { Some(self.top()) }
|
|
}
|
|
|
|
/// Returns the number of elements the queue can hold without reallocating
|
|
fn capacity(&self) -> uint { vec::capacity(&self.data) }
|
|
|
|
fn reserve(&mut self, n: uint) { vec::reserve(&mut self.data, n) }
|
|
|
|
fn reserve_at_least(&mut self, n: uint) {
|
|
vec::reserve_at_least(&mut self.data, n)
|
|
}
|
|
|
|
/// Pop the greatest item from the queue - fails if empty
|
|
fn pop(&mut self) -> T {
|
|
let mut item = self.data.pop();
|
|
if !self.is_empty() { item <-> self.data[0]; self.siftdown(0); }
|
|
item
|
|
}
|
|
|
|
/// Pop the greatest item from the queue - None if empty
|
|
fn maybe_pop(&mut self) -> Option<T> {
|
|
if self.is_empty() { None } else { Some(self.pop()) }
|
|
}
|
|
|
|
/// Push an item onto the queue
|
|
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
|
|
fn push_pop(&mut self, mut item: T) -> T {
|
|
if !self.is_empty() && self.data[0] > item {
|
|
item <-> self.data[0];
|
|
self.siftdown(0);
|
|
}
|
|
item
|
|
}
|
|
|
|
/// Optimized version of a pop followed by a push - fails if empty
|
|
fn replace(&mut self, mut item: T) -> T {
|
|
item <-> self.data[0];
|
|
self.siftdown(0);
|
|
item
|
|
}
|
|
|
|
/// Consume the PriorityQueue and return the underlying vector
|
|
fn to_vec(self) -> ~[T] { let PriorityQueue{data: v} = self; v }
|
|
|
|
/// Consume the PriorityQueue and return a vector in sorted
|
|
/// (ascending) order
|
|
fn to_sorted_vec(self) -> ~[T] {
|
|
let mut q = self;
|
|
let mut end = q.len();
|
|
while end > 1 {
|
|
end -= 1;
|
|
q.data[end] <-> q.data[0];
|
|
q.siftdown_range(0, end)
|
|
}
|
|
q.to_vec()
|
|
}
|
|
|
|
/// Create an empty PriorityQueue
|
|
fn new() -> PriorityQueue<T> { PriorityQueue{data: ~[],} }
|
|
|
|
/// Create a PriorityQueue from a vector (heapify)
|
|
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
|
|
// junk 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.
|
|
|
|
priv fn siftup(&mut self, start: uint, mut pos: uint) {
|
|
unsafe {
|
|
let new = *addr_of(&self.data[pos]);
|
|
|
|
while pos > start {
|
|
let parent = (pos - 1) >> 1;
|
|
if new > self.data[parent] {
|
|
let mut x = rusti::init();
|
|
x <-> self.data[parent];
|
|
rusti::move_val_init(&mut self.data[pos], x);
|
|
pos = parent;
|
|
loop
|
|
}
|
|
break
|
|
}
|
|
rusti::move_val_init(&mut self.data[pos], new);
|
|
}
|
|
}
|
|
|
|
priv fn siftdown_range(&mut self, mut pos: uint, end: uint) {
|
|
unsafe {
|
|
let start = pos;
|
|
let new = *addr_of(&self.data[pos]);
|
|
|
|
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 mut x = rusti::init();
|
|
x <-> self.data[child];
|
|
rusti::move_val_init(&mut self.data[pos], x);
|
|
pos = child;
|
|
child = 2 * pos + 1;
|
|
}
|
|
|
|
rusti::move_val_init(&mut self.data[pos], new);
|
|
self.siftup(start, pos);
|
|
}
|
|
}
|
|
|
|
priv fn siftdown(&mut self, pos: uint) {
|
|
let len = self.len();
|
|
self.siftdown_range(pos, len);
|
|
}
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use sort::merge_sort;
|
|
use core::cmp::le;
|
|
use priority_queue::PriorityQueue::{from_vec, new};
|
|
|
|
#[test]
|
|
fn test_top_and_pop() {
|
|
let data = ~[2, 4, 6, 2, 1, 8, 10, 3, 5, 7, 0, 9, 1];
|
|
let mut sorted = merge_sort(data, le);
|
|
let mut heap = from_vec(data);
|
|
while !heap.is_empty() {
|
|
assert!(heap.top() == sorted.last());
|
|
assert!(heap.pop() == sorted.pop());
|
|
}
|
|
}
|
|
|
|
#[test]
|
|
fn test_push() {
|
|
let mut heap = from_vec(~[2, 4, 9]);
|
|
assert!(heap.len() == 3);
|
|
assert!(*heap.top() == 9);
|
|
heap.push(11);
|
|
assert!(heap.len() == 4);
|
|
assert!(*heap.top() == 11);
|
|
heap.push(5);
|
|
assert!(heap.len() == 5);
|
|
assert!(*heap.top() == 11);
|
|
heap.push(27);
|
|
assert!(heap.len() == 6);
|
|
assert!(*heap.top() == 27);
|
|
heap.push(3);
|
|
assert!(heap.len() == 7);
|
|
assert!(*heap.top() == 27);
|
|
heap.push(103);
|
|
assert!(heap.len() == 8);
|
|
assert!(*heap.top() == 103);
|
|
}
|
|
|
|
#[test]
|
|
fn test_push_unique() {
|
|
let mut heap = from_vec(~[~2, ~4, ~9]);
|
|
assert!(heap.len() == 3);
|
|
assert!(*heap.top() == ~9);
|
|
heap.push(~11);
|
|
assert!(heap.len() == 4);
|
|
assert!(*heap.top() == ~11);
|
|
heap.push(~5);
|
|
assert!(heap.len() == 5);
|
|
assert!(*heap.top() == ~11);
|
|
heap.push(~27);
|
|
assert!(heap.len() == 6);
|
|
assert!(*heap.top() == ~27);
|
|
heap.push(~3);
|
|
assert!(heap.len() == 7);
|
|
assert!(*heap.top() == ~27);
|
|
heap.push(~103);
|
|
assert!(heap.len() == 8);
|
|
assert!(*heap.top() == ~103);
|
|
}
|
|
|
|
#[test]
|
|
fn test_push_pop() {
|
|
let mut heap = from_vec(~[5, 5, 2, 1, 3]);
|
|
assert!(heap.len() == 5);
|
|
assert!(heap.push_pop(6) == 6);
|
|
assert!(heap.len() == 5);
|
|
assert!(heap.push_pop(0) == 5);
|
|
assert!(heap.len() == 5);
|
|
assert!(heap.push_pop(4) == 5);
|
|
assert!(heap.len() == 5);
|
|
assert!(heap.push_pop(1) == 4);
|
|
assert!(heap.len() == 5);
|
|
}
|
|
|
|
#[test]
|
|
fn test_replace() {
|
|
let mut heap = from_vec(~[5, 5, 2, 1, 3]);
|
|
assert!(heap.len() == 5);
|
|
assert!(heap.replace(6) == 5);
|
|
assert!(heap.len() == 5);
|
|
assert!(heap.replace(0) == 6);
|
|
assert!(heap.len() == 5);
|
|
assert!(heap.replace(4) == 5);
|
|
assert!(heap.len() == 5);
|
|
assert!(heap.replace(1) == 4);
|
|
assert!(heap.len() == 5);
|
|
}
|
|
|
|
fn check_to_vec(data: ~[int]) {
|
|
let heap = from_vec(data);
|
|
assert!(merge_sort(heap.to_vec(), le) == merge_sort(data, le));
|
|
assert!(heap.to_sorted_vec() == merge_sort(data, le));
|
|
}
|
|
|
|
#[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]
|
|
#[ignore(cfg(windows))]
|
|
fn test_empty_pop() { let mut heap = new::<int>(); heap.pop(); }
|
|
|
|
#[test]
|
|
fn test_empty_maybe_pop() {
|
|
let mut heap = new::<int>();
|
|
assert!(heap.maybe_pop().is_none());
|
|
}
|
|
|
|
#[test]
|
|
#[should_fail]
|
|
#[ignore(cfg(windows))]
|
|
fn test_empty_top() { let empty = new::<int>(); empty.top(); }
|
|
|
|
#[test]
|
|
fn test_empty_maybe_top() {
|
|
let empty = new::<int>();
|
|
assert!(empty.maybe_top().is_none());
|
|
}
|
|
|
|
#[test]
|
|
#[should_fail]
|
|
#[ignore(cfg(windows))]
|
|
fn test_empty_replace() { let mut heap = new(); heap.replace(5); }
|
|
}
|