Files
addr2line
adler
aho_corasick
ansi_term
atty
backtrace
base64
bincode
bitflags
bitmaps
bstr
byteorder
bytes
bytesize
cargo
cargo_platform
cfg_if
chrono
clap
color_backtrace
corpus_database
corpus_database_dsl
corpus_extractor
corpus_manager
corpus_manager_driver
corpus_queries_derive
corpus_queries_impl
crates_index
crates_io
crc32fast
crossbeam_queue
crossbeam_utils
crypto_hash
csv
csv_core
curl
curl_sys
darling
darling_core
darling_macro
datafrog
datapond
datapond_derive
datapond_macro
either
encoding_rs
env_logger
error_chain
failure
failure_derive
filetime
flate2
fnv
foreign_types
foreign_types_shared
form_urlencoded
fs2
futures
futures_channel
futures_core
futures_io
futures_macro
futures_sink
futures_task
futures_util
async_await
future
io
lock
stream
task
getrandom
gimli
git2
git2_curl
glob
globset
h2
hashbrown
heck
hex
home
http
http_body
httparse
httpdate
humantime
hyper
hyper_tls
ident_case
idna
ignore
im_rc
indexmap
iovec
ipnet
itertools
itoa
jobserver
lazy_static
lazycell
libc
libgit2_sys
libnghttp2_sys
libssh2_sys
libz_sys
lock_api
log
log_derive
matches
maybe_uninit
memchr
mime
miniz_oxide
mio
mio_uds
native_tls
nix
num_cpus
num_integer
num_traits
object
once_cell
opener
openssl
openssl_probe
openssl_sys
parking_lot
parking_lot_core
percent_encoding
pest
pin_project
pin_project_lite
pin_utils
ppv_lite86
print_stats
proc_macro2
proc_macro_error
proc_macro_error_attr
proc_macro_hack
proc_macro_nested
quick_error
quote
rand
rand_chacha
rand_core
rand_xoshiro
regex
regex_automata
regex_syntax
remove_dir_all
reqwest
rustc
rustc_demangle
rustc_hash
rustc_workspace_hack
rustfix
rustwide
ryu
same_file
scopeguard
semver
semver_parser
serde
serde_derive
serde_ignored
serde_json
serde_urlencoded
shell_escape
signal_hook_registry
simplelog
sized_chunks
slab
smallvec
socket2
strip_ansi_escapes
strsim
structopt
structopt_derive
syn
synstructure
tar
tempdir
tempfile
termcolor
textwrap
thiserror
thiserror_impl
thread_local
time
tinyvec
tinyvec_macros
tokio
future
io
loom
macros
net
park
runtime
sync
task
time
util
tokio_executor
tokio_io
tokio_native_tls
tokio_process
tokio_reactor
tokio_signal
tokio_stream
tokio_sync
tokio_util
toml
tower_service
tracing
tracing_core
tracing_futures
try_lock
typenum
ucd_trie
unicode_bidi
unicode_normalization
unicode_segmentation
unicode_width
unicode_xid
url
utf8parse
vec_map
vte
walkdir
want
xattr
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

use crate::vector::FocusMut;
use rand_core::{RngCore, SeedableRng};
use std::cmp::Ordering;

fn gen_range<R: RngCore>(rng: &mut R, min: usize, max: usize) -> usize {
    let range = max - min;
    min + (rng.next_u64() as usize % range)
}

// Ported from the Java version at:
//    http://www.cs.princeton.edu/~rs/talks/QuicksortIsOptimal.pdf
// Should be O(n) to O(n log n)
fn do_quicksort<A, F, R>(
    vector: &mut FocusMut<'_, A>,
    left: usize,
    right: usize,
    cmp: &F,
    rng: &mut R,
) where
    A: Clone,
    F: Fn(&A, &A) -> Ordering,
    R: RngCore,
{
    if right <= left {
        return;
    }

    let l = left as isize;
    let r = right as isize;
    let p = gen_range(rng, left, right + 1) as isize;
    let mut l1 = l;
    let mut r1 = r;
    let mut l2 = l - 1;
    let mut r2 = r;

    vector.swap(r as usize, p as usize);
    loop {
        while l1 != r && vector.pair(l1 as usize, r as usize, |a, b| cmp(a, b)) == Ordering::Less {
            l1 += 1;
        }
        r1 -= 1;
        while r1 != r && vector.pair(r as usize, r1 as usize, |a, b| cmp(a, b)) == Ordering::Less {
            if r1 == l {
                break;
            }
            r1 -= 1;
        }
        if l1 >= r1 {
            break;
        }
        vector.swap(l1 as usize, r1 as usize);
        if l1 != r && vector.pair(l1 as usize, r as usize, |a, b| cmp(a, b)) == Ordering::Equal {
            l2 += 1;
            vector.swap(l2 as usize, l1 as usize);
        }
        if r1 != r && vector.pair(r as usize, r1 as usize, |a, b| cmp(a, b)) == Ordering::Equal {
            r2 -= 1;
            vector.swap(r1 as usize, r2 as usize);
        }
    }
    vector.swap(l1 as usize, r as usize);

    r1 = l1 - 1;
    l1 += 1;
    let mut k = l;
    while k < l2 {
        vector.swap(k as usize, r1 as usize);
        r1 -= 1;
        k += 1;
    }
    k = r - 1;
    while k > r2 {
        vector.swap(l1 as usize, k as usize);
        k -= 1;
        l1 += 1;
    }

    if r1 >= 0 {
        do_quicksort(vector, left, r1 as usize, cmp, rng);
    }
    do_quicksort(vector, l1 as usize, right, cmp, rng);
}

pub(crate) fn quicksort<A, F>(vector: &mut FocusMut<'_, A>, left: usize, right: usize, cmp: &F)
where
    A: Clone,
    F: Fn(&A, &A) -> Ordering,
{
    let mut rng = rand_xoshiro::Xoshiro256Plus::seed_from_u64(0);
    do_quicksort(vector, left, right, cmp, &mut rng);
}

#[cfg(test)]
mod test {
    use super::*;
    use crate::test::is_sorted;
    use crate::vector::proptest::vector;
    use ::proptest::num::i32;
    use ::proptest::proptest;

    proptest! {
        #[test]
        fn test_quicksort(ref input in vector(i32::ANY, 0..1000)) {
            let mut vec = input.clone();
            let len = vec.len();
            if len > 1 {
                quicksort(&mut vec.focus_mut(), 0, len - 1, &Ord::cmp);
            }
            assert!(is_sorted(vec));
        }
    }
}