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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711
//! `FixedBitSet` is a simple fixed size set of bits.
//!
//! ### Crate features
//!
//! - `std` (default feature)
//! Disabling this feature disables using std and instead uses crate alloc.
//!
//! ### SIMD Acceleration
//! `fixedbitset` is written with SIMD in mind. The backing store and set operations will use aligned SIMD data types and instructions when compiling
//! for compatible target platforms. The use of SIMD generally enables better performance in many set and batch operations (i.e. intersection/union/inserting a range).
//!
//! When SIMD is not available on the target, the crate will gracefully fallback to a default implementation. It is intended to add support for other SIMD architectures
//! once they appear in stable Rust.
//!
//! Currently only SSE2/AVX/AVX2 on x86/x86_64 and wasm32 SIMD are supported as this is what stable Rust supports.
#![no_std]
#![deny(clippy::undocumented_unsafe_blocks)]
extern crate alloc;
use alloc::{vec, vec::Vec};
mod block;
mod range;
#[cfg(feature = "serde")]
extern crate serde;
#[cfg(feature = "serde")]
mod serde_impl;
use core::fmt::Write;
use core::fmt::{Binary, Display, Error, Formatter};
use core::cmp::Ordering;
use core::hash::Hash;
use core::iter::{Chain, FusedIterator};
use core::mem::ManuallyDrop;
use core::mem::MaybeUninit;
use core::ops::{BitAnd, BitAndAssign, BitOr, BitOrAssign, BitXor, BitXorAssign, Index};
use core::ptr::NonNull;
pub use range::IndexRange;
pub(crate) const BITS: usize = core::mem::size_of::<Block>() * 8;
#[cfg(feature = "serde")]
pub(crate) const BYTES: usize = core::mem::size_of::<Block>();
use block::Block as SimdBlock;
pub type Block = usize;
#[inline]
fn div_rem(x: usize, denominator: usize) -> (usize, usize) {
(x / denominator, x % denominator)
}
fn vec_into_parts<T>(vec: Vec<T>) -> (NonNull<T>, usize, usize) {
let mut vec = ManuallyDrop::new(vec);
(
// SAFETY: A Vec's internal pointer is always non-null.
unsafe { NonNull::new_unchecked(vec.as_mut_ptr()) },
vec.capacity(),
vec.len(),
)
}
/// `FixedBitSet` is a simple fixed size set of bits that each can
/// be enabled (1 / **true**) or disabled (0 / **false**).
///
/// The bit set has a fixed capacity in terms of enabling bits (and the
/// capacity can grow using the `grow` method).
///
/// Derived traits depend on both the zeros and ones, so [0,1] is not equal to
/// [0,1,0].
#[derive(Debug, Eq)]
pub struct FixedBitSet {
pub(crate) data: NonNull<MaybeUninit<SimdBlock>>,
capacity: usize,
/// length in bits
pub(crate) length: usize,
}
// SAFETY: FixedBitset contains no thread-local state and can be safely sent between threads
unsafe impl Send for FixedBitSet {}
// SAFETY: FixedBitset does not provide simultaneous unsynchronized mutable access to the
// underlying buffer.
unsafe impl Sync for FixedBitSet {}
impl FixedBitSet {
/// Create a new empty **FixedBitSet**.
pub const fn new() -> Self {
FixedBitSet {
data: NonNull::dangling(),
capacity: 0,
length: 0,
}
}
/// Create a new **FixedBitSet** with a specific number of bits,
/// all initially clear.
pub fn with_capacity(bits: usize) -> Self {
let (mut blocks, rem) = div_rem(bits, SimdBlock::BITS);
blocks += (rem > 0) as usize;
Self::from_blocks_and_len(vec![SimdBlock::NONE; blocks], bits)
}
#[inline]
fn from_blocks_and_len(data: Vec<SimdBlock>, length: usize) -> Self {
let (data, capacity, _) = vec_into_parts(data);
FixedBitSet {
data: data.cast(),
capacity,
length,
}
}
/// Create a new **FixedBitSet** with a specific number of bits,
/// initialized from provided blocks.
///
/// If the blocks are not the exact size needed for the capacity
/// they will be padded with zeros (if shorter) or truncated to
/// the capacity (if longer).
///
/// For example:
/// ```
/// let data = vec![4];
/// let bs = fixedbitset::FixedBitSet::with_capacity_and_blocks(4, data);
/// assert_eq!(format!("{:b}", bs), "0010");
/// ```
pub fn with_capacity_and_blocks<I: IntoIterator<Item = Block>>(bits: usize, blocks: I) -> Self {
let mut bitset = Self::with_capacity(bits);
for (subblock, value) in bitset.as_mut_slice().iter_mut().zip(blocks.into_iter()) {
*subblock = value;
}
bitset
}
/// Grow capacity to **bits**, all new bits initialized to zero
#[inline]
pub fn grow(&mut self, bits: usize) {
#[cold]
#[track_caller]
#[inline(never)]
fn do_grow(slf: &mut FixedBitSet, bits: usize) {
// SAFETY: The provided fill is initialized to NONE.
unsafe { slf.grow_inner(bits, MaybeUninit::new(SimdBlock::NONE)) };
}
if bits > self.length {
do_grow(self, bits);
}
}
/// # Safety
/// If `fill` is uninitialized, the memory must not be accessed and must be immediately
/// written over
#[inline(always)]
unsafe fn grow_inner(&mut self, bits: usize, fill: MaybeUninit<SimdBlock>) {
// SAFETY: The data pointer and capacity were created from a Vec initially. The block
// len is identical to that of the original.
let mut data = unsafe {
Vec::from_raw_parts(self.data.as_ptr(), self.simd_block_len(), self.capacity)
};
let (mut blocks, rem) = div_rem(bits, SimdBlock::BITS);
blocks += (rem > 0) as usize;
data.resize(blocks, fill);
let (data, capacity, _) = vec_into_parts(data);
self.data = data;
self.capacity = capacity;
self.length = bits;
}
#[inline]
unsafe fn get_unchecked(&self, subblock: usize) -> &Block {
&*self.data.as_ptr().cast::<Block>().add(subblock)
}
#[inline]
unsafe fn get_unchecked_mut(&mut self, subblock: usize) -> &mut Block {
&mut *self.data.as_ptr().cast::<Block>().add(subblock)
}
#[inline]
fn usize_len(&self) -> usize {
let (mut blocks, rem) = div_rem(self.length, BITS);
blocks += (rem > 0) as usize;
blocks
}
#[inline]
fn simd_block_len(&self) -> usize {
let (mut blocks, rem) = div_rem(self.length, SimdBlock::BITS);
blocks += (rem > 0) as usize;
blocks
}
#[inline]
fn batch_count_ones(blocks: impl IntoIterator<Item = Block>) -> usize {
blocks.into_iter().map(|x| x.count_ones() as usize).sum()
}
#[inline]
fn as_simd_slice(&self) -> &[SimdBlock] {
// SAFETY: The slice constructed is within bounds of the underlying allocation. This function
// is called with a read-only borrow so no other write can happen as long as the returned borrow lives.
unsafe { core::slice::from_raw_parts(self.data.as_ptr().cast(), self.simd_block_len()) }
}
#[inline]
fn as_mut_simd_slice(&mut self) -> &mut [SimdBlock] {
// SAFETY: The slice constructed is within bounds of the underlying allocation. This function
// is called with a mutable borrow so no other read or write can happen as long as the returned borrow lives.
unsafe { core::slice::from_raw_parts_mut(self.data.as_ptr().cast(), self.simd_block_len()) }
}
#[inline]
fn as_simd_slice_uninit(&self) -> &[MaybeUninit<SimdBlock>] {
// SAFETY: The slice constructed is within bounds of the underlying allocation. This function
// is called with a read-only borrow so no other write can happen as long as the returned borrow lives.
unsafe { core::slice::from_raw_parts(self.data.as_ptr(), self.simd_block_len()) }
}
#[inline]
fn as_mut_simd_slice_uninit(&mut self) -> &mut [MaybeUninit<SimdBlock>] {
// SAFETY: The slice constructed is within bounds of the underlying allocation. This function
// is called with a mutable borrow so no other read or write can happen as long as the returned borrow lives.
unsafe { core::slice::from_raw_parts_mut(self.data.as_ptr(), self.simd_block_len()) }
}
/// Grows the internal size of the bitset before inserting a bit
///
/// Unlike `insert`, this cannot panic, but may allocate if the bit is outside of the existing buffer's range.
///
/// This is faster than calling `grow` then `insert` in succession.
#[inline]
pub fn grow_and_insert(&mut self, bits: usize) {
self.grow(bits + 1);
let (blocks, rem) = div_rem(bits, BITS);
// SAFETY: The above grow ensures that the block is inside the Vec's allocation.
unsafe {
*self.get_unchecked_mut(blocks) |= 1 << rem;
}
}
/// The length of the [`FixedBitSet`] in bits.
///
/// Note: `len` includes both set and unset bits.
/// ```
/// # use fixedbitset::FixedBitSet;
/// let bitset = FixedBitSet::with_capacity(10);
/// // there are 0 set bits, but 10 unset bits
/// assert_eq!(bitset.len(), 10);
/// ```
/// `len` does not return the count of set bits. For that, use
/// [`bitset.count_ones(..)`](FixedBitSet::count_ones) instead.
#[inline]
pub fn len(&self) -> usize {
self.length
}
/// `true` if the [`FixedBitSet`] is empty.
///
/// Note that an "empty" `FixedBitSet` is a `FixedBitSet` with
/// no bits (meaning: it's length is zero). If you want to check
/// if all bits are unset, use [`FixedBitSet::is_clear`].
///
/// ```
/// # use fixedbitset::FixedBitSet;
/// let bitset = FixedBitSet::with_capacity(10);
/// assert!(!bitset.is_empty());
///
/// let bitset = FixedBitSet::with_capacity(0);
/// assert!(bitset.is_empty());
/// ```
#[inline]
pub fn is_empty(&self) -> bool {
self.len() == 0
}
/// `true` if all bits in the [`FixedBitSet`] are unset.
///
/// As opposed to [`FixedBitSet::is_empty`], which is `true` only for
/// sets without any bits, set or unset.
///
/// ```
/// # use fixedbitset::FixedBitSet;
/// let mut bitset = FixedBitSet::with_capacity(10);
/// assert!(bitset.is_clear());
///
/// bitset.insert(2);
/// assert!(!bitset.is_clear());
/// ```
///
/// This is equivalent to [`bitset.count_ones(..) == 0`](FixedBitSet::count_ones).
#[inline]
pub fn is_clear(&self) -> bool {
self.as_simd_slice().iter().all(|block| block.is_empty())
}
/// Finds the lowest set bit in the bitset.
///
/// Returns `None` if there aren't any set bits.
///
/// ```
/// # use fixedbitset::FixedBitSet;
/// let mut bitset = FixedBitSet::with_capacity(10);
/// assert_eq!(bitset.minimum(), None);
///
/// bitset.insert(2);
/// assert_eq!(bitset.minimum(), Some(2));
/// bitset.insert(8);
/// assert_eq!(bitset.minimum(), Some(2));
/// ```
#[inline]
pub fn minimum(&self) -> Option<usize> {
let (block_idx, block) = self
.as_simd_slice()
.iter()
.enumerate()
.find(|&(_, block)| !block.is_empty())?;
let mut inner = 0;
let mut trailing = 0;
for subblock in block.into_usize_array() {
if subblock != 0 {
trailing = subblock.trailing_zeros() as usize;
break;
} else {
inner += BITS;
}
}
Some(block_idx * SimdBlock::BITS + inner + trailing)
}
/// Finds the highest set bit in the bitset.
///
/// Returns `None` if there aren't any set bits.
///
/// ```
/// # use fixedbitset::FixedBitSet;
/// let mut bitset = FixedBitSet::with_capacity(10);
/// assert_eq!(bitset.maximum(), None);
///
/// bitset.insert(8);
/// assert_eq!(bitset.maximum(), Some(8));
/// bitset.insert(2);
/// assert_eq!(bitset.maximum(), Some(8));
/// ```
#[inline]
pub fn maximum(&self) -> Option<usize> {
let (block_idx, block) = self
.as_simd_slice()
.iter()
.rev()
.enumerate()
.find(|&(_, block)| !block.is_empty())?;
let mut inner = 0;
let mut leading = 0;
for subblock in block.into_usize_array().iter().rev() {
if *subblock != 0 {
leading = subblock.leading_zeros() as usize;
break;
} else {
inner += BITS;
}
}
let max = self.simd_block_len() * SimdBlock::BITS;
Some(max - block_idx * SimdBlock::BITS - inner - leading - 1)
}
/// `true` if all bits in the [`FixedBitSet`] are set.
///
/// ```
/// # use fixedbitset::FixedBitSet;
/// let mut bitset = FixedBitSet::with_capacity(10);
/// assert!(!bitset.is_full());
///
/// bitset.insert_range(..);
/// assert!(bitset.is_full());
/// ```
///
/// This is equivalent to [`bitset.count_ones(..) == bitset.len()`](FixedBitSet::count_ones).
#[inline]
pub fn is_full(&self) -> bool {
self.contains_all_in_range(..)
}
/// Return **true** if the bit is enabled in the **FixedBitSet**,
/// **false** otherwise.
///
/// Note: bits outside the capacity are always disabled.
///
/// Note: Also available with index syntax: `bitset[bit]`.
#[inline]
pub fn contains(&self, bit: usize) -> bool {
(bit < self.length)
// SAFETY: The above check ensures that the block and bit are within bounds.
.then(|| unsafe { self.contains_unchecked(bit) })
.unwrap_or(false)
}
/// Return **true** if the bit is enabled in the **FixedBitSet**,
/// **false** otherwise.
///
/// Note: unlike `contains`, calling this with an invalid `bit`
/// is undefined behavior.
///
/// # Safety
/// `bit` must be less than `self.len()`
#[inline]
pub unsafe fn contains_unchecked(&self, bit: usize) -> bool {
let (block, i) = div_rem(bit, BITS);
(self.get_unchecked(block) & (1 << i)) != 0
}
/// Clear all bits.
#[inline]
pub fn clear(&mut self) {
for elt in self.as_mut_simd_slice().iter_mut() {
*elt = SimdBlock::NONE
}
}
/// Enable `bit`.
///
/// **Panics** if **bit** is out of bounds.
#[inline]
pub fn insert(&mut self, bit: usize) {
assert!(
bit < self.length,
"insert at index {} exceeds fixedbitset size {}",
bit,
self.length
);
// SAFETY: The above assertion ensures that the block is inside the Vec's allocation.
unsafe {
self.insert_unchecked(bit);
}
}
/// Enable `bit` without any length checks.
///
/// # Safety
/// `bit` must be less than `self.len()`
#[inline]
pub unsafe fn insert_unchecked(&mut self, bit: usize) {
let (block, i) = div_rem(bit, BITS);
// SAFETY: The above assertion ensures that the block is inside the Vec's allocation.
unsafe {
*self.get_unchecked_mut(block) |= 1 << i;
}
}
/// Disable `bit`.
///
/// **Panics** if **bit** is out of bounds.
#[inline]
pub fn remove(&mut self, bit: usize) {
assert!(
bit < self.length,
"remove at index {} exceeds fixedbitset size {}",
bit,
self.length
);
// SAFETY: The above assertion ensures that the block is inside the Vec's allocation.
unsafe {
self.remove_unchecked(bit);
}
}
/// Disable `bit` without any bounds checking.
///
/// # Safety
/// `bit` must be less than `self.len()`
#[inline]
pub unsafe fn remove_unchecked(&mut self, bit: usize) {
let (block, i) = div_rem(bit, BITS);
// SAFETY: The above assertion ensures that the block is inside the Vec's allocation.
unsafe {
*self.get_unchecked_mut(block) &= !(1 << i);
}
}
/// Enable `bit`, and return its previous value.
///
/// **Panics** if **bit** is out of bounds.
#[inline]
pub fn put(&mut self, bit: usize) -> bool {
assert!(
bit < self.length,
"put at index {} exceeds fixedbitset size {}",
bit,
self.length
);
// SAFETY: The above assertion ensures that the block is inside the Vec's allocation.
unsafe { self.put_unchecked(bit) }
}
/// Enable `bit`, and return its previous value without doing any bounds checking.
///
/// # Safety
/// `bit` must be less than `self.len()`
#[inline]
pub unsafe fn put_unchecked(&mut self, bit: usize) -> bool {
let (block, i) = div_rem(bit, BITS);
// SAFETY: The above assertion ensures that the block is inside the Vec's allocation.
unsafe {
let word = self.get_unchecked_mut(block);
let prev = *word & (1 << i) != 0;
*word |= 1 << i;
prev
}
}
/// Toggle `bit` (inverting its state).
///
/// ***Panics*** if **bit** is out of bounds
#[inline]
pub fn toggle(&mut self, bit: usize) {
assert!(
bit < self.length,
"toggle at index {} exceeds fixedbitset size {}",
bit,
self.length
);
// SAFETY: The above assertion ensures that the block is inside the Vec's allocation.
unsafe {
self.toggle_unchecked(bit);
}
}
/// Toggle `bit` (inverting its state) without any bounds checking.
///
/// # Safety
/// `bit` must be less than `self.len()`
#[inline]
pub unsafe fn toggle_unchecked(&mut self, bit: usize) {
let (block, i) = div_rem(bit, BITS);
// SAFETY: The above assertion ensures that the block is inside the Vec's allocation.
unsafe {
*self.get_unchecked_mut(block) ^= 1 << i;
}
}
/// Sets a bit to the provided `enabled` value.
///
/// **Panics** if **bit** is out of bounds.
#[inline]
pub fn set(&mut self, bit: usize, enabled: bool) {
assert!(
bit < self.length,
"set at index {} exceeds fixedbitset size {}",
bit,
self.length
);
// SAFETY: The above assertion ensures that the block is inside the Vec's allocation.
unsafe {
self.set_unchecked(bit, enabled);
}
}
/// Sets a bit to the provided `enabled` value without doing any bounds checking.
///
/// # Safety
/// `bit` must be less than `self.len()`
#[inline]
pub unsafe fn set_unchecked(&mut self, bit: usize, enabled: bool) {
let (block, i) = div_rem(bit, BITS);
// SAFETY: The above assertion ensures that the block is inside the Vec's allocation.
let elt = unsafe { self.get_unchecked_mut(block) };
if enabled {
*elt |= 1 << i;
} else {
*elt &= !(1 << i);
}
}
/// Copies boolean value from specified bit to the specified bit.
///
/// If `from` is out-of-bounds, `to` will be unset.
///
/// **Panics** if **to** is out of bounds.
#[inline]
pub fn copy_bit(&mut self, from: usize, to: usize) {
assert!(
to < self.length,
"copy to index {} exceeds fixedbitset size {}",
to,
self.length
);
let enabled = self.contains(from);
// SAFETY: The above assertion ensures that the block is inside the Vec's allocation.
unsafe { self.set_unchecked(to, enabled) };
}
/// Copies boolean value from specified bit to the specified bit.
///
/// Note: unlike `copy_bit`, calling this with an invalid `from`
/// is undefined behavior.
///
/// # Safety
/// `to` must both be less than `self.len()`
#[inline]
pub unsafe fn copy_bit_unchecked(&mut self, from: usize, to: usize) {
// SAFETY: Caller must ensure that `from` is within bounds.
let enabled = self.contains_unchecked(from);
// SAFETY: Caller must ensure that `to` is within bounds.
self.set_unchecked(to, enabled);
}
/// Count the number of set bits in the given bit range.
///
/// This function is potentially much faster than using `ones(other).count()`.
/// Use `..` to count the whole content of the bitset.
///
/// **Panics** if the range extends past the end of the bitset.
#[inline]
pub fn count_ones<T: IndexRange>(&self, range: T) -> usize {
Self::batch_count_ones(Masks::new(range, self.length).map(|(block, mask)| {
// SAFETY: Masks cannot return a block index that is out of range.
unsafe { *self.get_unchecked(block) & mask }
}))
}
/// Count the number of unset bits in the given bit range.
///
/// This function is potentially much faster than using `zeroes(other).count()`.
/// Use `..` to count the whole content of the bitset.
///
/// **Panics** if the range extends past the end of the bitset.
#[inline]
pub fn count_zeroes<T: IndexRange>(&self, range: T) -> usize {
Self::batch_count_ones(Masks::new(range, self.length).map(|(block, mask)| {
// SAFETY: Masks cannot return a block index that is out of range.
unsafe { !*self.get_unchecked(block) & mask }
}))
}
/// Sets every bit in the given range to the given state (`enabled`)
///
/// Use `..` to set the whole bitset.
///
/// **Panics** if the range extends past the end of the bitset.
#[inline]
pub fn set_range<T: IndexRange>(&mut self, range: T, enabled: bool) {
if enabled {
self.insert_range(range);
} else {
self.remove_range(range);
}
}
/// Enables every bit in the given range.
///
/// Use `..` to make the whole bitset ones.
///
/// **Panics** if the range extends past the end of the bitset.
#[inline]
pub fn insert_range<T: IndexRange>(&mut self, range: T) {
for (block, mask) in Masks::new(range, self.length) {
// SAFETY: Masks cannot return a block index that is out of range.
let block = unsafe { self.get_unchecked_mut(block) };
*block |= mask;
}
}
/// Disables every bit in the given range.
///
/// Use `..` to make the whole bitset ones.
///
/// **Panics** if the range extends past the end of the bitset.
#[inline]
pub fn remove_range<T: IndexRange>(&mut self, range: T) {
for (block, mask) in Masks::new(range, self.length) {
// SAFETY: Masks cannot return a block index that is out of range.
let block = unsafe { self.get_unchecked_mut(block) };
*block &= !mask;
}
}
/// Toggles (inverts) every bit in the given range.
///
/// Use `..` to toggle the whole bitset.
///
/// **Panics** if the range extends past the end of the bitset.
#[inline]
pub fn toggle_range<T: IndexRange>(&mut self, range: T) {
for (block, mask) in Masks::new(range, self.length) {
// SAFETY: Masks cannot return a block index that is out of range.
let block = unsafe { self.get_unchecked_mut(block) };
*block ^= mask;
}
}
/// Checks if the bitset contains every bit in the given range.
///
/// **Panics** if the range extends past the end of the bitset.
#[inline]
pub fn contains_all_in_range<T: IndexRange>(&self, range: T) -> bool {
for (block, mask) in Masks::new(range, self.length) {
// SAFETY: Masks cannot return a block index that is out of range.
let block = unsafe { self.get_unchecked(block) };
if block & mask != mask {
return false;
}
}
true
}
/// Checks if the bitset contains at least one set bit in the given range.
///
/// **Panics** if the range extends past the end of the bitset.
#[inline]
pub fn contains_any_in_range<T: IndexRange>(&self, range: T) -> bool {
for (block, mask) in Masks::new(range, self.length) {
// SAFETY: Masks cannot return a block index that is out of range.
let block = unsafe { self.get_unchecked(block) };
if block & mask != 0 {
return true;
}
}
false
}
/// View the bitset as a slice of `Block` blocks
#[inline]
pub fn as_slice(&self) -> &[Block] {
// SAFETY: The bits from both usize and Block are required to be reinterprettable, and
// neither have any padding or alignment issues. The slice constructed is within bounds
// of the underlying allocation. This function is called with a read-only borrow so
// no other write can happen as long as the returned borrow lives.
unsafe {
let ptr = self.data.as_ptr().cast::<Block>();
core::slice::from_raw_parts(ptr, self.usize_len())
}
}
/// View the bitset as a mutable slice of `Block` blocks. Writing past the bitlength in the last
/// will cause `contains` to return potentially incorrect results for bits past the bitlength.
#[inline]
pub fn as_mut_slice(&mut self) -> &mut [Block] {
// SAFETY: The bits from both usize and Block are required to be reinterprettable, and
// neither have any padding or alignment issues. The slice constructed is within bounds
// of the underlying allocation. This function is called with a mutable borrow so
// no other read or write can happen as long as the returned borrow lives.
unsafe {
let ptr = self.data.as_ptr().cast::<Block>();
core::slice::from_raw_parts_mut(ptr, self.usize_len())
}
}
/// Iterates over all enabled bits.
///
/// Iterator element is the index of the `1` bit, type `usize`.
#[inline]
pub fn ones(&self) -> Ones {
match self.as_slice().split_first() {
Some((&first_block, rem)) => {
let (&last_block, rem) = rem.split_last().unwrap_or((&0, rem));
Ones {
bitset_front: first_block,
bitset_back: last_block,
block_idx_front: 0,
block_idx_back: (1 + rem.len()) * BITS,
remaining_blocks: rem.iter(),
}
}
None => Ones {
bitset_front: 0,
bitset_back: 0,
block_idx_front: 0,
block_idx_back: 0,
remaining_blocks: [].iter(),
},
}
}
/// Iterates over all enabled bits.
///
/// Iterator element is the index of the `1` bit, type `usize`.
/// Unlike `ones`, this function consumes the `FixedBitset`.
pub fn into_ones(self) -> IntoOnes {
let ptr = self.data.as_ptr().cast();
let len = self.simd_block_len() * SimdBlock::USIZE_COUNT;
// SAFETY:
// - ptr comes from self.data, so it is valid;
// - self.data is valid for self.data.len() SimdBlocks,
// which is exactly self.data.len() * SimdBlock::USIZE_COUNT usizes;
// - we will keep this slice around only as long as self.data is,
// so it won't become dangling.
let slice = unsafe { core::slice::from_raw_parts(ptr, len) };
// SAFETY: The data pointer and capacity were created from a Vec initially. The block
// len is identical to that of the original.
let data: Vec<SimdBlock> = unsafe {
Vec::from_raw_parts(
self.data.as_ptr().cast(),
self.simd_block_len(),
self.capacity,
)
};
let mut iter = slice.iter().copied();
core::mem::forget(self);
IntoOnes {
bitset_front: iter.next().unwrap_or(0),
bitset_back: iter.next_back().unwrap_or(0),
block_idx_front: 0,
block_idx_back: len.saturating_sub(1) * BITS,
remaining_blocks: iter,
_buf: data,
}
}
/// Iterates over all disabled bits.
///
/// Iterator element is the index of the `0` bit, type `usize`.
#[inline]
pub fn zeroes(&self) -> Zeroes {
match self.as_slice().split_first() {
Some((&block, rem)) => Zeroes {
bitset: !block,
block_idx: 0,
len: self.len(),
remaining_blocks: rem.iter(),
},
None => Zeroes {
bitset: !0,
block_idx: 0,
len: self.len(),
remaining_blocks: [].iter(),
},
}
}
/// Returns a lazy iterator over the intersection of two `FixedBitSet`s
pub fn intersection<'a>(&'a self, other: &'a FixedBitSet) -> Intersection<'a> {
Intersection {
iter: self.ones(),
other,
}
}
/// Returns a lazy iterator over the union of two `FixedBitSet`s.
pub fn union<'a>(&'a self, other: &'a FixedBitSet) -> Union<'a> {
Union {
iter: self.ones().chain(other.difference(self)),
}
}
/// Returns a lazy iterator over the difference of two `FixedBitSet`s. The difference of `a`
/// and `b` is the elements of `a` which are not in `b`.
pub fn difference<'a>(&'a self, other: &'a FixedBitSet) -> Difference<'a> {
Difference {
iter: self.ones(),
other,
}
}
/// Returns a lazy iterator over the symmetric difference of two `FixedBitSet`s.
/// The symmetric difference of `a` and `b` is the elements of one, but not both, sets.
pub fn symmetric_difference<'a>(&'a self, other: &'a FixedBitSet) -> SymmetricDifference<'a> {
SymmetricDifference {
iter: self.difference(other).chain(other.difference(self)),
}
}
/// In-place union of two `FixedBitSet`s.
///
/// On calling this method, `self`'s capacity may be increased to match `other`'s.
pub fn union_with(&mut self, other: &FixedBitSet) {
if other.len() >= self.len() {
self.grow(other.len());
}
self.as_mut_simd_slice()
.iter_mut()
.zip(other.as_simd_slice().iter())
.for_each(|(x, y)| *x |= *y);
}
/// In-place intersection of two `FixedBitSet`s.
///
/// On calling this method, `self`'s capacity will remain the same as before.
pub fn intersect_with(&mut self, other: &FixedBitSet) {
let me = self.as_mut_simd_slice();
let other = other.as_simd_slice();
me.iter_mut().zip(other.iter()).for_each(|(x, y)| {
*x &= *y;
});
let mn = core::cmp::min(me.len(), other.len());
for wd in &mut me[mn..] {
*wd = SimdBlock::NONE;
}
}
/// In-place difference of two `FixedBitSet`s.
///
/// On calling this method, `self`'s capacity will remain the same as before.
pub fn difference_with(&mut self, other: &FixedBitSet) {
self.as_mut_simd_slice()
.iter_mut()
.zip(other.as_simd_slice().iter())
.for_each(|(x, y)| {
*x &= !*y;
});
// There's no need to grow self or do any other adjustments.
//
// * If self is longer than other, the bits at the end of self won't be affected since other
// has them implicitly set to 0.
// * If other is longer than self, the bits at the end of other are irrelevant since self
// has them set to 0 anyway.
}
/// In-place symmetric difference of two `FixedBitSet`s.
///
/// On calling this method, `self`'s capacity may be increased to match `other`'s.
pub fn symmetric_difference_with(&mut self, other: &FixedBitSet) {
if other.len() >= self.len() {
self.grow(other.len());
}
self.as_mut_simd_slice()
.iter_mut()
.zip(other.as_simd_slice().iter())
.for_each(|(x, y)| {
*x ^= *y;
});
}
/// Computes how many bits would be set in the union between two bitsets.
///
/// This is potentially much faster than using `union(other).count()`. Unlike
/// other methods like using [`union_with`] followed by [`count_ones`], this
/// does not mutate in place or require separate allocations.
#[inline]
pub fn union_count(&self, other: &FixedBitSet) -> usize {
let me = self.as_slice();
let other = other.as_slice();
let count = Self::batch_count_ones(me.iter().zip(other.iter()).map(|(x, y)| (*x | *y)));
match other.len().cmp(&me.len()) {
Ordering::Greater => count + Self::batch_count_ones(other[me.len()..].iter().copied()),
Ordering::Less => count + Self::batch_count_ones(me[other.len()..].iter().copied()),
Ordering::Equal => count,
}
}
/// Computes how many bits would be set in the intersection between two bitsets.
///
/// This is potentially much faster than using `intersection(other).count()`. Unlike
/// other methods like using [`intersect_with`] followed by [`count_ones`], this
/// does not mutate in place or require separate allocations.
#[inline]
pub fn intersection_count(&self, other: &FixedBitSet) -> usize {
Self::batch_count_ones(
self.as_slice()
.iter()
.zip(other.as_slice())
.map(|(x, y)| (*x & *y)),
)
}
/// Computes how many bits would be set in the difference between two bitsets.
///
/// This is potentially much faster than using `difference(other).count()`. Unlike
/// other methods like using [`difference_with`] followed by [`count_ones`], this
/// does not mutate in place or require separate allocations.
#[inline]
pub fn difference_count(&self, other: &FixedBitSet) -> usize {
Self::batch_count_ones(
self.as_slice()
.iter()
.zip(other.as_slice().iter())
.map(|(x, y)| (*x & !*y)),
)
}
/// Computes how many bits would be set in the symmetric difference between two bitsets.
///
/// This is potentially much faster than using `symmetric_difference(other).count()`. Unlike
/// other methods like using [`symmetric_difference_with`] followed by [`count_ones`], this
/// does not mutate in place or require separate allocations.
#[inline]
pub fn symmetric_difference_count(&self, other: &FixedBitSet) -> usize {
let me = self.as_slice();
let other = other.as_slice();
let count = Self::batch_count_ones(me.iter().zip(other.iter()).map(|(x, y)| (*x ^ *y)));
match other.len().cmp(&me.len()) {
Ordering::Greater => count + Self::batch_count_ones(other[me.len()..].iter().copied()),
Ordering::Less => count + Self::batch_count_ones(me[other.len()..].iter().copied()),
Ordering::Equal => count,
}
}
/// Returns `true` if `self` has no elements in common with `other`. This
/// is equivalent to checking for an empty intersection.
pub fn is_disjoint(&self, other: &FixedBitSet) -> bool {
self.as_simd_slice()
.iter()
.zip(other.as_simd_slice())
.all(|(x, y)| (*x & *y).is_empty())
}
/// Returns `true` if the set is a subset of another, i.e. `other` contains
/// at least all the values in `self`.
pub fn is_subset(&self, other: &FixedBitSet) -> bool {
let me = self.as_simd_slice();
let other = other.as_simd_slice();
me.iter()
.zip(other.iter())
.all(|(x, y)| x.andnot(*y).is_empty())
&& me.iter().skip(other.len()).all(|x| x.is_empty())
}
/// Returns `true` if the set is a superset of another, i.e. `self` contains
/// at least all the values in `other`.
pub fn is_superset(&self, other: &FixedBitSet) -> bool {
other.is_subset(self)
}
}
impl Hash for FixedBitSet {
fn hash<H: core::hash::Hasher>(&self, state: &mut H) {
self.length.hash(state);
self.as_simd_slice().hash(state);
}
}
impl PartialEq for FixedBitSet {
fn eq(&self, other: &Self) -> bool {
self.length == other.length && self.as_simd_slice().eq(other.as_simd_slice())
}
}
impl PartialOrd for FixedBitSet {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl Ord for FixedBitSet {
fn cmp(&self, other: &Self) -> Ordering {
self.length
.cmp(&other.length)
.then_with(|| self.as_simd_slice().cmp(other.as_simd_slice()))
}
}
impl Default for FixedBitSet {
fn default() -> Self {
Self::new()
}
}
impl Drop for FixedBitSet {
fn drop(&mut self) {
// SAFETY: The data pointer and capacity were created from a Vec initially. The block
// len is identical to that of the original.
drop(unsafe {
Vec::from_raw_parts(self.data.as_ptr(), self.simd_block_len(), self.capacity)
});
}
}
impl Binary for FixedBitSet {
fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
if f.alternate() {
f.write_str("0b")?;
}
for i in 0..self.length {
if self[i] {
f.write_char('1')?;
} else {
f.write_char('0')?;
}
}
Ok(())
}
}
impl Display for FixedBitSet {
fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
Binary::fmt(&self, f)
}
}
/// An iterator producing elements in the difference of two sets.
///
/// This struct is created by the [`FixedBitSet::difference`] method.
pub struct Difference<'a> {
iter: Ones<'a>,
other: &'a FixedBitSet,
}
impl<'a> Iterator for Difference<'a> {
type Item = usize;
#[inline]
fn next(&mut self) -> Option<Self::Item> {
self.iter.by_ref().find(|&nxt| !self.other.contains(nxt))
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
impl<'a> DoubleEndedIterator for Difference<'a> {
fn next_back(&mut self) -> Option<Self::Item> {
self.iter
.by_ref()
.rev()
.find(|&nxt| !self.other.contains(nxt))
}
}
// Difference will continue to return None once it first returns None.
impl<'a> FusedIterator for Difference<'a> {}
/// An iterator producing elements in the symmetric difference of two sets.
///
/// This struct is created by the [`FixedBitSet::symmetric_difference`] method.
pub struct SymmetricDifference<'a> {
iter: Chain<Difference<'a>, Difference<'a>>,
}
impl<'a> Iterator for SymmetricDifference<'a> {
type Item = usize;
#[inline]
fn next(&mut self) -> Option<Self::Item> {
self.iter.next()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
impl<'a> DoubleEndedIterator for SymmetricDifference<'a> {
fn next_back(&mut self) -> Option<Self::Item> {
self.iter.next_back()
}
}
// SymmetricDifference will continue to return None once it first returns None.
impl<'a> FusedIterator for SymmetricDifference<'a> {}
/// An iterator producing elements in the intersection of two sets.
///
/// This struct is created by the [`FixedBitSet::intersection`] method.
pub struct Intersection<'a> {
iter: Ones<'a>,
other: &'a FixedBitSet,
}
impl<'a> Iterator for Intersection<'a> {
type Item = usize; // the bit position of the '1'
#[inline]
fn next(&mut self) -> Option<Self::Item> {
self.iter.by_ref().find(|&nxt| self.other.contains(nxt))
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
impl<'a> DoubleEndedIterator for Intersection<'a> {
fn next_back(&mut self) -> Option<Self::Item> {
self.iter
.by_ref()
.rev()
.find(|&nxt| self.other.contains(nxt))
}
}
// Intersection will continue to return None once it first returns None.
impl<'a> FusedIterator for Intersection<'a> {}
/// An iterator producing elements in the union of two sets.
///
/// This struct is created by the [`FixedBitSet::union`] method.
pub struct Union<'a> {
iter: Chain<Ones<'a>, Difference<'a>>,
}
impl<'a> Iterator for Union<'a> {
type Item = usize;
#[inline]
fn next(&mut self) -> Option<Self::Item> {
self.iter.next()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
impl<'a> DoubleEndedIterator for Union<'a> {
fn next_back(&mut self) -> Option<Self::Item> {
self.iter.next_back()
}
}
// Union will continue to return None once it first returns None.
impl<'a> FusedIterator for Union<'a> {}
struct Masks {
first_block: usize,
first_mask: usize,
last_block: usize,
last_mask: usize,
}
impl Masks {
#[inline]
fn new<T: IndexRange>(range: T, length: usize) -> Masks {
let start = range.start().unwrap_or(0);
let end = range.end().unwrap_or(length);
assert!(
start <= end && end <= length,
"invalid range {}..{} for a fixedbitset of size {}",
start,
end,
length
);
let (first_block, first_rem) = div_rem(start, BITS);
let (last_block, last_rem) = div_rem(end, BITS);
Masks {
first_block,
first_mask: usize::MAX << first_rem,
last_block,
last_mask: (usize::MAX >> 1) >> (BITS - last_rem - 1),
// this is equivalent to `MAX >> (BITS - x)` with correct semantics when x == 0.
}
}
}
impl Iterator for Masks {
type Item = (usize, usize);
#[inline]
fn next(&mut self) -> Option<Self::Item> {
match self.first_block.cmp(&self.last_block) {
Ordering::Less => {
let res = (self.first_block, self.first_mask);
self.first_block += 1;
self.first_mask = !0;
Some(res)
}
Ordering::Equal => {
let mask = self.first_mask & self.last_mask;
let res = if mask == 0 {
None
} else {
Some((self.first_block, mask))
};
self.first_block += 1;
res
}
Ordering::Greater => None,
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
(self.first_block..=self.last_block).size_hint()
}
}
// Masks will continue to return None once it first returns None.
impl FusedIterator for Masks {}
// Masks's size_hint implementation is exact. It never returns an
// unbounded value and always returns an exact number of values.
impl ExactSizeIterator for Masks {}
/// An iterator producing the indices of the set bit in a set.
///
/// This struct is created by the [`FixedBitSet::ones`] method.
pub struct Ones<'a> {
bitset_front: usize,
bitset_back: usize,
block_idx_front: usize,
block_idx_back: usize,
remaining_blocks: core::slice::Iter<'a, usize>,
}
impl<'a> Ones<'a> {
#[inline]
pub fn last_positive_bit_and_unset(n: &mut usize) -> usize {
// Find the last set bit using x & -x
let last_bit = *n & n.wrapping_neg();
// Find the position of the last set bit
let position = last_bit.trailing_zeros();
// Unset the last set bit
*n &= *n - 1;
position as usize
}
#[inline]
fn first_positive_bit_and_unset(n: &mut usize) -> usize {
/* Identify the first non zero bit */
let bit_idx = n.leading_zeros();
/* set that bit to zero */
let mask = !((1_usize) << (BITS as u32 - bit_idx - 1));
n.bitand_assign(mask);
bit_idx as usize
}
}
impl<'a> DoubleEndedIterator for Ones<'a> {
fn next_back(&mut self) -> Option<Self::Item> {
while self.bitset_back == 0 {
match self.remaining_blocks.next_back() {
None => {
if self.bitset_front != 0 {
self.bitset_back = 0;
self.block_idx_back = self.block_idx_front;
return Some(
self.block_idx_front + BITS
- Self::first_positive_bit_and_unset(&mut self.bitset_front)
- 1,
);
} else {
return None;
}
}
Some(next_block) => {
self.bitset_back = *next_block;
self.block_idx_back -= BITS;
}
};
}
Some(
self.block_idx_back - Self::first_positive_bit_and_unset(&mut self.bitset_back) + BITS
- 1,
)
}
}
impl<'a> Iterator for Ones<'a> {
type Item = usize; // the bit position of the '1'
#[inline]
fn next(&mut self) -> Option<Self::Item> {
while self.bitset_front == 0 {
match self.remaining_blocks.next() {
Some(next_block) => {
self.bitset_front = *next_block;
self.block_idx_front += BITS;
}
None => {
if self.bitset_back != 0 {
// not needed for iteration, but for size_hint
self.block_idx_front = self.block_idx_back;
self.bitset_front = 0;
return Some(
self.block_idx_back
+ Self::last_positive_bit_and_unset(&mut self.bitset_back),
);
} else {
return None;
}
}
};
}
Some(self.block_idx_front + Self::last_positive_bit_and_unset(&mut self.bitset_front))
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
(
0,
(Some(self.block_idx_back - self.block_idx_front + 2 * BITS)),
)
}
}
// Ones will continue to return None once it first returns None.
impl<'a> FusedIterator for Ones<'a> {}
/// An iterator producing the indices of the set bit in a set.
///
/// This struct is created by the [`FixedBitSet::ones`] method.
pub struct Zeroes<'a> {
bitset: usize,
block_idx: usize,
len: usize,
remaining_blocks: core::slice::Iter<'a, usize>,
}
impl<'a> Iterator for Zeroes<'a> {
type Item = usize; // the bit position of the '1'
#[inline]
fn next(&mut self) -> Option<Self::Item> {
while self.bitset == 0 {
self.bitset = !*self.remaining_blocks.next()?;
self.block_idx += BITS;
}
let t = self.bitset & (0_usize).wrapping_sub(self.bitset);
let r = self.bitset.trailing_zeros() as usize;
self.bitset ^= t;
let bit = self.block_idx + r;
// The remaining zeroes beyond the length of the bitset must be excluded.
if bit < self.len {
Some(bit)
} else {
None
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
(0, Some(self.len))
}
}
// Zeroes will stop returning Some when exhausted.
impl<'a> FusedIterator for Zeroes<'a> {}
impl Clone for FixedBitSet {
#[inline]
fn clone(&self) -> Self {
Self::from_blocks_and_len(Vec::from(self.as_simd_slice()), self.length)
}
#[inline]
fn clone_from(&mut self, source: &Self) {
if self.length < source.length {
// SAFETY: `fill` is uninitialized, but is immediately initialized from `source`.
unsafe { self.grow_inner(source.length, MaybeUninit::uninit()) };
}
let me = self.as_mut_simd_slice_uninit();
let them = source.as_simd_slice_uninit();
match me.len().cmp(&them.len()) {
Ordering::Greater => {
let (head, tail) = me.split_at_mut(them.len());
head.copy_from_slice(them);
tail.fill(MaybeUninit::new(SimdBlock::NONE));
}
Ordering::Equal => me.copy_from_slice(them),
// The grow_inner above ensures that self is at least as large as source.
// so this branch is unreachable.
Ordering::Less => {}
}
self.length = source.length;
}
}
/// Return **true** if the bit is enabled in the bitset,
/// or **false** otherwise.
///
/// Note: bits outside the capacity are always disabled, and thus
/// indexing a FixedBitSet will not panic.
impl Index<usize> for FixedBitSet {
type Output = bool;
#[inline]
fn index(&self, bit: usize) -> &bool {
if self.contains(bit) {
&true
} else {
&false
}
}
}
/// Sets the bit at index **i** to **true** for each item **i** in the input **src**.
impl Extend<usize> for FixedBitSet {
fn extend<I: IntoIterator<Item = usize>>(&mut self, src: I) {
let iter = src.into_iter();
for i in iter {
if i >= self.len() {
self.grow(i + 1);
}
self.put(i);
}
}
}
/// Return a FixedBitSet containing bits set to **true** for every bit index in
/// the iterator, other bits are set to **false**.
impl FromIterator<usize> for FixedBitSet {
fn from_iter<I: IntoIterator<Item = usize>>(src: I) -> Self {
let mut fbs = FixedBitSet::with_capacity(0);
fbs.extend(src);
fbs
}
}
pub struct IntoOnes {
bitset_front: Block,
bitset_back: Block,
block_idx_front: usize,
block_idx_back: usize,
remaining_blocks: core::iter::Copied<core::slice::Iter<'static, usize>>,
// Keep buf along so that `remaining_blocks` remains valid.
_buf: Vec<SimdBlock>,
}
impl IntoOnes {
#[inline]
pub fn last_positive_bit_and_unset(n: &mut Block) -> usize {
// Find the last set bit using x & -x
let last_bit = *n & n.wrapping_neg();
// Find the position of the last set bit
let position = last_bit.trailing_zeros();
// Unset the last set bit
*n &= *n - 1;
position as usize
}
#[inline]
fn first_positive_bit_and_unset(n: &mut Block) -> usize {
/* Identify the first non zero bit */
let bit_idx = n.leading_zeros();
/* set that bit to zero */
let mask = !((1_usize) << (BITS as u32 - bit_idx - 1));
n.bitand_assign(mask);
bit_idx as usize
}
}
impl DoubleEndedIterator for IntoOnes {
fn next_back(&mut self) -> Option<Self::Item> {
while self.bitset_back == 0 {
match self.remaining_blocks.next_back() {
None => {
if self.bitset_front != 0 {
self.bitset_back = 0;
self.block_idx_back = self.block_idx_front;
return Some(
self.block_idx_front + BITS
- Self::first_positive_bit_and_unset(&mut self.bitset_front)
- 1,
);
} else {
return None;
}
}
Some(next_block) => {
self.bitset_back = next_block;
self.block_idx_back -= BITS;
}
};
}
Some(
self.block_idx_back - Self::first_positive_bit_and_unset(&mut self.bitset_back) + BITS
- 1,
)
}
}
impl Iterator for IntoOnes {
type Item = usize; // the bit position of the '1'
#[inline]
fn next(&mut self) -> Option<Self::Item> {
while self.bitset_front == 0 {
match self.remaining_blocks.next() {
Some(next_block) => {
self.bitset_front = next_block;
self.block_idx_front += BITS;
}
None => {
if self.bitset_back != 0 {
// not needed for iteration, but for size_hint
self.block_idx_front = self.block_idx_back;
self.bitset_front = 0;
return Some(
self.block_idx_back
+ Self::last_positive_bit_and_unset(&mut self.bitset_back),
);
} else {
return None;
}
}
};
}
Some(self.block_idx_front + Self::last_positive_bit_and_unset(&mut self.bitset_front))
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
(
0,
(Some(self.block_idx_back - self.block_idx_front + 2 * BITS)),
)
}
}
// Ones will continue to return None once it first returns None.
impl FusedIterator for IntoOnes {}
impl<'a> BitAnd for &'a FixedBitSet {
type Output = FixedBitSet;
fn bitand(self, other: &FixedBitSet) -> FixedBitSet {
let (short, long) = {
if self.len() <= other.len() {
(self.as_simd_slice(), other.as_simd_slice())
} else {
(other.as_simd_slice(), self.as_simd_slice())
}
};
let mut data = Vec::from(short);
for (data, block) in data.iter_mut().zip(long.iter()) {
*data &= *block;
}
let len = core::cmp::min(self.len(), other.len());
FixedBitSet::from_blocks_and_len(data, len)
}
}
impl BitAndAssign for FixedBitSet {
fn bitand_assign(&mut self, other: Self) {
self.intersect_with(&other);
}
}
impl BitAndAssign<&Self> for FixedBitSet {
fn bitand_assign(&mut self, other: &Self) {
self.intersect_with(other);
}
}
impl<'a> BitOr for &'a FixedBitSet {
type Output = FixedBitSet;
fn bitor(self, other: &FixedBitSet) -> FixedBitSet {
let (short, long) = {
if self.len() <= other.len() {
(self.as_simd_slice(), other.as_simd_slice())
} else {
(other.as_simd_slice(), self.as_simd_slice())
}
};
let mut data = Vec::from(long);
for (data, block) in data.iter_mut().zip(short.iter()) {
*data |= *block;
}
let len = core::cmp::max(self.len(), other.len());
FixedBitSet::from_blocks_and_len(data, len)
}
}
impl BitOrAssign for FixedBitSet {
fn bitor_assign(&mut self, other: Self) {
self.union_with(&other);
}
}
impl BitOrAssign<&Self> for FixedBitSet {
fn bitor_assign(&mut self, other: &Self) {
self.union_with(other);
}
}
impl<'a> BitXor for &'a FixedBitSet {
type Output = FixedBitSet;
fn bitxor(self, other: &FixedBitSet) -> FixedBitSet {
let (short, long) = {
if self.len() <= other.len() {
(self.as_simd_slice(), other.as_simd_slice())
} else {
(other.as_simd_slice(), self.as_simd_slice())
}
};
let mut data = Vec::from(long);
for (data, block) in data.iter_mut().zip(short.iter()) {
*data ^= *block;
}
let len = core::cmp::max(self.len(), other.len());
FixedBitSet::from_blocks_and_len(data, len)
}
}
impl BitXorAssign for FixedBitSet {
fn bitxor_assign(&mut self, other: Self) {
self.symmetric_difference_with(&other);
}
}
impl BitXorAssign<&Self> for FixedBitSet {
fn bitxor_assign(&mut self, other: &Self) {
self.symmetric_difference_with(other);
}
}