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#![no_std]
#![cfg_attr(test, feature(plugin))]
#![cfg_attr(test, plugin(quickcheck_macros))]
#[cfg(test)] extern crate quickcheck;
#[cfg(test)] extern crate std;
use core::mem;
#[inline] pub fn push<A, F: Fn(&A, &A) -> bool>(arity: usize, f: F, xs: &mut [A]) {
assert!(xs.len() > 0);
let mut n = xs.len() - 1;
loop {
if n == 0 { return };
let m = (n-1)/arity;
if !f(&xs[n], &xs[m]) { return };
xs.swap(m, n);
n = m;
}
}
#[inline] pub fn pop<A, F: Fn(&A, &A) -> bool>(arity: usize, f: F, xs: &mut [A]) {
assert!(xs.len() > 0);
let l = xs.len()-1;
xs.swap(0, l);
sift_down(arity, f, &mut xs[0..l], 0);
}
#[inline] pub fn build<A, F: Fn(&A, &A) -> bool>(arity: usize, f: F, xs: &mut [A]) {
if xs.len() <= 1 { return };
for k in (0..xs.len()>>1).rev() { sift_down(arity, &f, xs, k) }
}
#[inline] pub fn sort<A, F: Fn(&A, &A) -> bool>(arity: usize, f: F, xs: &mut [A]) {
for l in (1..xs.len()).rev() {
pop(arity, &f, &mut xs[0..l+1]);
}
}
#[inline] pub fn replace_root<A, F: Fn(&A, &A) -> bool>(arity: usize, f: F, xs: &mut [A], x: A) -> A {
assert!(xs.len() > 0);
let y = mem::replace(&mut xs[0], x);
sift_down(arity, f, xs, 0);
y
}
#[inline] fn sift_down<A, F: Fn(&A, &A) -> bool>(arity: usize, f: F, xs: &mut [A], mut m: usize) {
let g: &Fn(Option<&A>, Option<&A>) -> bool = &|opt_x, opt_y| map_opt_2_or(false, &f, opt_x, opt_y);
loop {
if m >= xs.len() { return };
let n = {
let mut n = m;
for k in (0..arity).map(|k| arity*m+k+1) { if g(xs.get(k), Some(&xs[n])) { n = k } }
n
};
if m == n { return };
xs.swap(m, n);
m = n;
}
}
#[inline] pub fn is_heap<A, F: Fn(&A, &A) -> bool>(arity: usize, f: F, xs: &[A]) -> bool {
let g: &Fn(Option<&A>, Option<&A>) -> bool = &|opt_x, opt_y| map_opt_2_or(false, &f, opt_x, opt_y);
!(0..xs.len()).any(|n| (0..arity).any(|k| g(xs.get(n*arity+k+1), Some(&xs[n]))))
}
#[inline] fn map_opt_2_or<A, B, C, F: Fn(A, B) -> C>(c: C, f: F, opt_a: Option<A>, opt_b: Option<B>) -> C {
match (opt_a, opt_b) { (Some(a), Some(b)) => f(a, b), _ => c }
}
#[cfg(test)] mod tests {
use quickcheck::*;
use std::vec::*;
use super::*;
fn greater<A: Ord>(x: &A, y: &A) -> bool { x > y }
fn is_sorted(xs: &[usize]) -> bool {
(1..xs.len()).all(|k| xs[k-1] <= xs[k])
}
#[quickcheck] fn build_test(arity: usize, mut xv: Vec<usize>) -> TestResult {
if arity <= 1 { return TestResult::discard() };
let xs = &mut xv[..];
build(arity, greater, xs);
TestResult::from_bool(is_heap(arity, greater, xs))
}
#[quickcheck] fn push_test(arity: usize, mut xv: Vec<usize>) -> TestResult {
if arity <= 1 { return TestResult::discard() };
if xv.len() == 0 { return TestResult::discard() };
let xs = &mut xv[..];
let l = xs.len();
build(arity, greater, &mut xs[0..l]);
push(arity, greater, xs);
TestResult::from_bool(is_heap(arity, greater, xs))
}
#[quickcheck] fn pop_test(arity: usize, mut xv: Vec<usize>) -> TestResult {
if arity <= 1 { return TestResult::discard() };
if xv.len() == 0 { return TestResult::discard() };
let xs = &mut xv[..];
let l = xs.len()-1;
build(arity, greater, xs);
pop(arity, greater, xs);
TestResult::from_bool(is_heap(arity, greater, &mut xs[0..l]) && xs[l] >= xs[0])
}
#[quickcheck] fn sort_test(arity: usize, mut xv: Vec<usize>) -> TestResult {
if arity <= 1 { return TestResult::discard() };
let xs = &mut xv[..];
build(arity, greater, xs);
sort(arity, greater, xs);
TestResult::from_bool(is_sorted(xs))
}
}