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
// 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 std::mem::{replace, swap};
use std::ops::{Range, RangeBounds};
use std::ptr::null;
use std::sync::atomic::{AtomicPtr, Ordering};
use crate::nodes::chunk::Chunk;
use crate::sync::Lock;
use crate::util::{to_range, PoolRef, Ref};
use crate::vector::{
Iter, IterMut, RRBPool, Vector,
VectorInner::{Full, Inline, Single},
RRB,
};
/// Focused indexing over a [`Vector`][Vector].
///
/// By remembering the last tree node accessed through an index lookup and the
/// path we took to get there, we can speed up lookups for adjacent indices
/// tremendously. Lookups on indices in the same node are instantaneous, and
/// lookups on sibling nodes are also very fast.
///
/// A `Focus` can also be used as a restricted view into a vector, using the
/// [`narrow`][narrow] and [`split_at`][split_at] methods.
///
/// # When should I use a `Focus` for better performance?
///
/// `Focus` is useful when you need to perform a large number of index lookups
/// that are more likely than not to be close to each other. It's usually worth
/// using a `Focus` in any situation where you're batching a lot of index
/// lookups together, even if they're not obviously adjacent - there's likely
/// to be some performance gain for even completely random access.
///
/// If you're just iterating forwards or backwards over the [`Vector`][Vector]
/// in order, you're better off with a regular iterator, which, in fact, is
/// implemented using a `Focus`, but provides a simpler interface.
///
/// If you're just doing a very small number of index lookups, the setup cost
/// for the `Focus` is probably not worth it.
///
/// A `Focus` is never faster than an index lookup on a small [`Vector`][Vector]
/// with a length below the internal RRB tree's branching factor of 64.
///
/// # Examples
///
/// This example is contrived, as the better way to iterate forwards or
/// backwards over a vector is with an actual iterator. Even so, the version
/// using a `Focus` should run nearly an order of magnitude faster than the
/// version using index lookups at a length of 1000. It should also be noted
/// that [`vector::Iter`][Iter] is actually implemented using a `Focus` behind
/// the scenes, so the performance of the two should be identical.
///
/// ```rust
/// # #[macro_use] extern crate imbl;
/// # use imbl::vector::Vector;
/// # use std::iter::FromIterator;
/// let mut vec: Vector<i64> = Vector::from_iter(0..1000);
///
/// // Summing a vector, the slow way:
/// let mut sum = 0;
/// for i in 0..1000 {
/// sum += *vec.get(i).unwrap();
/// }
/// assert_eq!(499500, sum);
///
/// // Summing a vector faster using a Focus:
/// let mut sum = 0;
/// let mut focus = vec.focus();
/// for i in 0..1000 {
/// sum += *focus.get(i).unwrap();
/// }
/// assert_eq!(499500, sum);
///
/// // And the easy way, for completeness:
/// let sum: i64 = vec.iter().sum();
/// assert_eq!(499500, sum);
/// ```
///
/// [Vector]: enum.Vector.html
/// [Iter]: struct.Iter.html
/// [narrow]: #method.narrow
/// [split_at]: #method.split_at
pub enum Focus<'a, A> {
#[doc(hidden)]
/// The Single variant is a focus of a simple Vector that can be represented as a single slice.
Single(&'a [A]),
#[doc(hidden)]
/// The Full variant is a focus of a more complex Vector that cannot be represented as a single slice.
Full(TreeFocus<A>),
}
impl<'a, A> Focus<'a, A>
where
A: 'a,
{
/// Construct a `Focus` for a [`Vector`][Vector].
///
/// [Vector]: enum.Vector.html
pub fn new(vector: &'a Vector<A>) -> Self {
match &vector.vector {
Inline(_, chunk) => Focus::Single(chunk),
Single(_, chunk) => Focus::Single(chunk),
Full(_, tree) => Focus::Full(TreeFocus::new(tree)),
}
}
/// Get the length of the focused [`Vector`][Vector].
///
/// [Vector]: enum.Vector.html
pub fn len(&self) -> usize {
match self {
Focus::Single(chunk) => chunk.len(),
Focus::Full(tree) => tree.len(),
}
}
/// Test if the focused [`Vector`][Vector] is empty.
///
/// [Vector]: enum.Vector.html
pub fn is_empty(&self) -> bool {
self.len() == 0
}
/// Get a reference to the value at a given index.
pub fn get(&mut self, index: usize) -> Option<&A> {
match self {
Focus::Single(chunk) => chunk.get(index),
Focus::Full(tree) => tree.get(index),
}
}
/// Get a reference to the value at a given index.
///
/// Panics if the index is out of bounds.
pub fn index(&mut self, index: usize) -> &A {
self.get(index).expect("index out of bounds")
}
/// Get the chunk for the given index.
///
/// This gives you a reference to the leaf node that contains the index,
/// along with its start and end indices.
pub fn chunk_at(&mut self, index: usize) -> (Range<usize>, &[A]) {
let len = self.len();
if index >= len {
panic!("vector::Focus::chunk_at: index out of bounds");
}
match self {
Focus::Single(chunk) => (0..len, chunk),
Focus::Full(tree) => tree.get_chunk(index),
}
}
/// Narrow the focus onto a subslice of the vector.
///
/// `Focus::narrow(range)` has the same effect as `&slice[range]`, without
/// actually modifying the underlying vector.
///
/// Panics if the range isn't fully inside the current focus.
///
/// ## Examples
///
/// ```rust
/// # #[macro_use] extern crate imbl;
/// # use imbl::vector::Vector;
/// # use std::iter::FromIterator;
/// let vec = Vector::from_iter(0..1000);
/// let narrowed = vec.focus().narrow(100..200);
/// let narrowed_vec = narrowed.into_iter().cloned().collect();
/// assert_eq!(Vector::from_iter(100..200), narrowed_vec);
/// ```
///
/// [slice::split_at]: https://doc.rust-lang.org/std/primitive.slice.html#method.split_at
/// [Vector::split_at]: enum.Vector.html#method.split_at
#[must_use]
pub fn narrow<R>(self, range: R) -> Self
where
R: RangeBounds<usize>,
{
let r = to_range(&range, self.len());
if r.start >= r.end || r.start >= self.len() {
panic!("vector::Focus::narrow: range out of bounds");
}
match self {
Focus::Single(chunk) => Focus::Single(&chunk[r]),
Focus::Full(tree) => Focus::Full(tree.narrow(r)),
}
}
/// Split the focus into two.
///
/// Given an index `index`, consume the focus and produce two new foci, the
/// left onto indices `0..index`, and the right onto indices `index..N`
/// where `N` is the length of the current focus.
///
/// Panics if the index is out of bounds.
///
/// This is the moral equivalent of [`slice::split_at`][slice::split_at], in
/// that it leaves the underlying data structure unchanged, unlike
/// [`Vector::split_at`][Vector::split_at].
///
/// ## Examples
///
/// ```rust
/// # #[macro_use] extern crate imbl;
/// # use imbl::vector::Vector;
/// # use std::iter::FromIterator;
/// let vec = Vector::from_iter(0..1000);
/// let (left, right) = vec.focus().split_at(500);
/// let left_vec = left.into_iter().cloned().collect();
/// let right_vec = right.into_iter().cloned().collect();
/// assert_eq!(Vector::from_iter(0..500), left_vec);
/// assert_eq!(Vector::from_iter(500..1000), right_vec);
/// ```
///
/// [slice::split_at]: https://doc.rust-lang.org/std/primitive.slice.html#method.split_at
/// [Vector::split_at]: enum.Vector.html#method.split_at
pub fn split_at(self, index: usize) -> (Self, Self) {
if index >= self.len() {
panic!("vector::Focus::split_at: index out of bounds");
}
match self {
Focus::Single(chunk) => {
let (left, right) = chunk.split_at(index);
(Focus::Single(left), Focus::Single(right))
}
Focus::Full(tree) => {
let (left, right) = tree.split_at(index);
(Focus::Full(left), Focus::Full(right))
}
}
}
}
impl<'a, A> IntoIterator for Focus<'a, A>
where
A: Clone + 'a,
{
type Item = &'a A;
type IntoIter = Iter<'a, A>;
fn into_iter(self) -> Self::IntoIter {
Iter::from_focus(self)
}
}
impl<'a, A> Clone for Focus<'a, A>
where
A: Clone + 'a,
{
fn clone(&self) -> Self {
match self {
Focus::Single(chunk) => Focus::Single(chunk),
Focus::Full(tree) => Focus::Full(tree.clone()),
}
}
}
pub struct TreeFocus<A> {
/// A clone of the Vector's internal tree that this focus points to. A clone ensures that we don't require a
/// reference to the original tree.
tree: RRB<A>,
/// The view represents the range of the tree that this TreeFocus can see. The view can be narrowed by calling
/// either the narrow or split_at methods.
view: Range<usize>,
/// The tree version of the Vector is represented as the concatenation of 2 chunks, followed by the tree root,
/// followed by 2 chunks. The middle_range refers to the range of the Vector that the tree covers.
middle_range: Range<usize>,
/// This implementation of a focus stores only a single chunk for the Vector. This chunk can refer to one of the 4
/// chunks front/back chunks or one of the leaves of the tree. The target_ptr is the pointer to the actual chunk
/// in question. The target_range is the range that the chunk represents.
target_range: Range<usize>,
target_ptr: *const Chunk<A>,
}
impl<A> Clone for TreeFocus<A> {
fn clone(&self) -> Self {
let tree = self.tree.clone();
TreeFocus {
view: self.view.clone(),
middle_range: self.middle_range.clone(),
target_range: 0..0,
target_ptr: null(),
tree,
}
}
}
unsafe impl<A: Send> Send for TreeFocus<A> {}
unsafe impl<A: Sync> Sync for TreeFocus<A> {}
#[inline]
fn contains<A: Ord>(range: &Range<A>, index: &A) -> bool {
*index >= range.start && *index < range.end
}
impl<A> TreeFocus<A> {
/// Creates a new TreeFocus for a Vector's RRB tree.
fn new(tree: &RRB<A>) -> Self {
let middle_start = tree.outer_f.len() + tree.inner_f.len();
let middle_end = middle_start + tree.middle.len();
TreeFocus {
tree: tree.clone(),
view: 0..tree.length,
middle_range: middle_start..middle_end,
target_range: 0..0,
target_ptr: null(),
}
}
/// Returns the number of elements that the TreeFocus is valid for.
fn len(&self) -> usize {
self.view.end - self.view.start
}
/// Restricts the TreeFocus to a subrange of itself.
fn narrow(self, mut view: Range<usize>) -> Self {
view.start += self.view.start;
view.end += self.view.start;
TreeFocus {
view,
middle_range: self.middle_range.clone(),
target_range: 0..0,
target_ptr: null(),
tree: self.tree,
}
}
/// Splits the TreeFocus into two disjoint foci. The first TreeFocus is valid for ..index while the
/// second is valid for index.. .
fn split_at(self, index: usize) -> (Self, Self) {
let len = self.len();
let left = self.clone().narrow(0..index);
let right = self.narrow(index..len);
(left, right)
}
/// Computes an absolute index in the RRBTree for the given index relative to the start of this TreeFocus.
fn physical_index(&self, index: usize) -> usize {
debug_assert!(index < self.view.end);
self.view.start + index
}
/// Computes a range relative to the TreeFocus given one that is absolute in the RRBTree.
fn logical_range(&self, range: &Range<usize>) -> Range<usize> {
(range.start - self.view.start)..(range.end - self.view.start)
}
/// Sets the internal chunk to the one that contains the given absolute index.
fn set_focus(&mut self, index: usize) {
if index < self.middle_range.start {
let outer_len = self.tree.outer_f.len();
if index < outer_len {
self.target_range = 0..outer_len;
self.target_ptr = &*self.tree.outer_f;
} else {
self.target_range = outer_len..self.middle_range.start;
self.target_ptr = &*self.tree.inner_f;
}
} else if index >= self.middle_range.end {
let outer_start = self.middle_range.end + self.tree.inner_b.len();
if index < outer_start {
self.target_range = self.middle_range.end..outer_start;
self.target_ptr = &*self.tree.inner_b;
} else {
self.target_range = outer_start..self.tree.length;
self.target_ptr = &*self.tree.outer_b;
}
} else {
let tree_index = index - self.middle_range.start;
let (range, ptr) = self
.tree
.middle
.lookup_chunk(self.tree.middle_level, 0, tree_index);
self.target_range =
(range.start + self.middle_range.start)..(range.end + self.middle_range.start);
self.target_ptr = ptr;
}
}
/// Gets the chunk that this TreeFocus is focused on.
fn get_focus(&self) -> &Chunk<A> {
unsafe { &*self.target_ptr }
}
/// Gets the value at the given index relative to the TreeFocus.
pub fn get(&mut self, index: usize) -> Option<&A> {
if index >= self.len() {
return None;
}
let phys_index = self.physical_index(index);
if !contains(&self.target_range, &phys_index) {
self.set_focus(phys_index);
}
let target_phys_index = phys_index - self.target_range.start;
Some(&self.get_focus()[target_phys_index])
}
/// Gets the chunk for an index as a slice and its corresponding range within the TreeFocus.
pub fn get_chunk(&mut self, index: usize) -> (Range<usize>, &[A]) {
let phys_index = self.physical_index(index);
if !contains(&self.target_range, &phys_index) {
self.set_focus(phys_index);
}
let mut slice: &[A] = self.get_focus();
let mut left = 0;
let mut right = 0;
if self.target_range.start < self.view.start {
left = self.view.start - self.target_range.start;
}
if self.target_range.end > self.view.end {
right = self.target_range.end - self.view.end;
}
slice = &slice[left..(slice.len() - right)];
let phys_range = (self.target_range.start + left)..(self.target_range.end - right);
(self.logical_range(&phys_range), slice)
}
}
/// A mutable version of [`Focus`][Focus].
///
/// See [`Focus`][Focus] for more details.
///
/// You can only build one `FocusMut` at a time for a vector, effectively
/// keeping a lock on the vector until you're done with the focus, which relies
/// on the structure of the vector not changing while it exists.
///
/// ```rust,compile_fail
/// # #[macro_use] extern crate imbl;
/// # use imbl::vector::Vector;
/// # use std::iter::FromIterator;
/// let mut vec = Vector::from_iter(0..1000);
/// let focus1 = vec.focus_mut();
/// // Fails here in 2015 edition because you're creating
/// // two mutable references to the same thing.
/// let focus2 = vec.focus_mut();
/// // Fails here in 2018 edition because creating focus2
/// // made focus1's lifetime go out of scope.
/// assert_eq!(Some(&0), focus1.get(0));
/// ```
///
/// On the other hand, you can split that one focus into multiple sub-focuses,
/// which is safe because they can't overlap:
///
/// ```rust
/// # #[macro_use] extern crate imbl;
/// # use imbl::vector::Vector;
/// # use std::iter::FromIterator;
/// let mut vec = Vector::from_iter(0..1000);
/// let focus = vec.focus_mut();
/// let (mut left, mut right) = focus.split_at(500);
/// assert_eq!(Some(&0), left.get(0));
/// assert_eq!(Some(&500), right.get(0));
/// ```
///
/// These sub-foci also work as a lock on the vector, even if the focus they
/// were created from goes out of scope.
///
/// ```rust,compile_fail
/// # #[macro_use] extern crate imbl;
/// # use imbl::vector::Vector;
/// # use std::iter::FromIterator;
/// let mut vec = Vector::from_iter(0..1000);
/// let (left, right) = {
/// let focus = vec.focus_mut();
/// focus.split_at(500)
/// };
/// // `left` and `right` are still in scope even if `focus` isn't, so we can't
/// // create another focus:
/// let focus2 = vec.focus_mut();
/// assert_eq!(Some(&0), left.get(0));
/// ```
///
/// [Focus]: enum.Focus.html
pub enum FocusMut<'a, A> {
#[doc(hidden)]
/// The Single variant is a focusmut of a simple Vector that can be represented as a single slice.
Single(RRBPool<A>, &'a mut [A]),
#[doc(hidden)]
/// The Full variant is a focus of a more complex Vector that cannot be represented as a single slice.
Full(RRBPool<A>, TreeFocusMut<'a, A>),
}
impl<'a, A> FocusMut<'a, A>
where
A: 'a,
{
/// Get the length of the focused `Vector`.
pub fn len(&self) -> usize {
match self {
FocusMut::Single(_, chunk) => chunk.len(),
FocusMut::Full(_, tree) => tree.len(),
}
}
/// Test if the focused `Vector` is empty.
pub fn is_empty(&self) -> bool {
self.len() == 0
}
/// Narrow the focus onto a subslice of the vector.
///
/// `FocusMut::narrow(range)` has the same effect as `&slice[range]`, without
/// actually modifying the underlying vector.
///
/// Panics if the range isn't fully inside the current focus.
///
/// ## Examples
///
/// ```rust
/// # #[macro_use] extern crate imbl;
/// # use imbl::vector::Vector;
/// # use std::iter::FromIterator;
/// let mut vec = Vector::from_iter(0..1000);
/// let narrowed = vec.focus_mut().narrow(100..200);
/// let narrowed_vec = narrowed.unmut().into_iter().cloned().collect();
/// assert_eq!(Vector::from_iter(100..200), narrowed_vec);
/// ```
///
/// [slice::split_at]: https://doc.rust-lang.org/std/primitive.slice.html#method.split_at
/// [Vector::split_at]: enum.Vector.html#method.split_at
#[must_use]
pub fn narrow<R>(self, range: R) -> Self
where
R: RangeBounds<usize>,
{
let r = to_range(&range, self.len());
if r.start > r.end || r.start > self.len() {
panic!("vector::FocusMut::narrow: range out of bounds");
}
match self {
FocusMut::Single(pool, chunk) => FocusMut::Single(pool, &mut chunk[r]),
FocusMut::Full(pool, tree) => FocusMut::Full(pool, tree.narrow(r)),
}
}
/// Split the focus into two.
///
/// Given an index `index`, consume the focus and produce two new foci, the
/// left onto indices `0..index`, and the right onto indices `index..N`
/// where `N` is the length of the current focus.
///
/// Panics if the index is out of bounds.
///
/// This is the moral equivalent of [`slice::split_at`][slice::split_at], in
/// that it leaves the underlying data structure unchanged, unlike
/// [`Vector::split_at`][Vector::split_at].
///
/// ## Examples
///
/// ```rust
/// # #[macro_use] extern crate imbl;
/// # use imbl::vector::Vector;
/// # use std::iter::FromIterator;
/// let mut vec = Vector::from_iter(0..1000);
/// {
/// let (left, right) = vec.focus_mut().split_at(500);
/// for ptr in left {
/// *ptr += 100;
/// }
/// for ptr in right {
/// *ptr -= 100;
/// }
/// }
/// let expected = Vector::from_iter(100..600)
/// + Vector::from_iter(400..900);
/// assert_eq!(expected, vec);
/// ```
///
/// [slice::split_at]: https://doc.rust-lang.org/std/primitive.slice.html#method.split_at
/// [Vector::split_at]: enum.Vector.html#method.split_at
#[allow(clippy::redundant_clone)]
pub fn split_at(self, index: usize) -> (Self, Self) {
if index > self.len() {
panic!("vector::FocusMut::split_at: index out of bounds");
}
match self {
FocusMut::Single(pool, chunk) => {
let (left, right) = chunk.split_at_mut(index);
(
FocusMut::Single(pool.clone(), left),
FocusMut::Single(pool, right),
)
}
FocusMut::Full(pool, tree) => {
let (left, right) = tree.split_at(index);
(
FocusMut::Full(pool.clone(), left),
FocusMut::Full(pool, right),
)
}
}
}
/// Convert a `FocusMut` into a `Focus`.
pub fn unmut(self) -> Focus<'a, A> {
match self {
FocusMut::Single(_, chunk) => Focus::Single(chunk),
FocusMut::Full(_, mut tree) => Focus::Full(TreeFocus {
tree: {
let t = tree.tree.lock().unwrap();
(*t).clone()
},
view: tree.view.clone(),
middle_range: tree.middle_range.clone(),
target_range: 0..0,
target_ptr: null(),
}),
}
}
}
impl<'a, A> FocusMut<'a, A>
where
A: Clone + 'a,
{
/// Construct a `FocusMut` for a `Vector`.
pub fn new(vector: &'a mut Vector<A>) -> Self {
match &mut vector.vector {
Inline(pool, chunk) => FocusMut::Single(pool.clone(), chunk),
Single(pool, chunk) => FocusMut::Single(
pool.clone(),
PoolRef::make_mut(&pool.value_pool, chunk).as_mut_slice(),
),
Full(pool, tree) => FocusMut::Full(pool.clone(), TreeFocusMut::new(tree)),
}
}
/// Get a reference to the value at a given index.
pub fn get(&mut self, index: usize) -> Option<&A> {
self.get_mut(index).map(|r| &*r)
}
/// Get a mutable reference to the value at a given index.
pub fn get_mut(&mut self, index: usize) -> Option<&mut A> {
match self {
FocusMut::Single(_, chunk) => chunk.get_mut(index),
FocusMut::Full(pool, tree) => tree.get(pool, index),
}
}
/// Get a reference to the value at a given index.
///
/// Panics if the index is out of bounds.
pub fn index(&mut self, index: usize) -> &A {
&*self.index_mut(index)
}
/// Get a mutable reference to the value at a given index.
///
/// Panics if the index is out of bounds.
#[allow(clippy::should_implement_trait)] // would if I could
pub fn index_mut(&mut self, index: usize) -> &mut A {
self.get_mut(index).expect("index out of bounds")
}
/// Update the value at a given index.
///
/// Returns `None` if the index is out of bounds, or the replaced value
/// otherwise.
pub fn set(&mut self, index: usize, value: A) -> Option<A> {
self.get_mut(index).map(|pos| replace(pos, value))
}
/// Swap the values at two given indices.
///
/// Panics if either index is out of bounds.
///
/// If the indices are equal, this function returns without doing anything.
pub fn swap(&mut self, a: usize, b: usize) {
if a == b {
return;
}
self.pair(a, b, |left, right| swap(left, right));
}
/// Lookup two indices simultaneously and run a function over them.
///
/// Useful because the borrow checker won't let you have more than one
/// mutable reference into the same data structure at any given time.
///
/// Panics if either index is out of bounds, or if they are the same index.
///
/// # Examples
///
/// ```rust
/// # #[macro_use] extern crate imbl;
/// # use imbl::vector::Vector;
/// # use std::iter::FromIterator;
/// let mut vec = vector![1, 2, 3, 4, 5];
/// vec.focus_mut().pair(1, 3, |a, b| *a += *b);
/// assert_eq!(vector![1, 6, 3, 4, 5], vec);
/// ```
pub fn pair<F, B>(&mut self, a: usize, b: usize, mut f: F) -> B
where
F: FnMut(&mut A, &mut A) -> B,
{
if a == b {
panic!("vector::FocusMut::pair: indices cannot be equal!");
}
let pa: *mut A = self.index_mut(a);
let pb: *mut A = self.index_mut(b);
unsafe { f(&mut *pa, &mut *pb) }
}
/// Lookup three indices simultaneously and run a function over them.
///
/// Useful because the borrow checker won't let you have more than one
/// mutable reference into the same data structure at any given time.
///
/// Panics if any index is out of bounds, or if any indices are equal.
///
/// # Examples
///
/// ```rust
/// # #[macro_use] extern crate imbl;
/// # use imbl::vector::Vector;
/// # use std::iter::FromIterator;
/// let mut vec = vector![1, 2, 3, 4, 5];
/// vec.focus_mut().triplet(0, 2, 4, |a, b, c| *a += *b + *c);
/// assert_eq!(vector![9, 2, 3, 4, 5], vec);
/// ```
pub fn triplet<F, B>(&mut self, a: usize, b: usize, c: usize, mut f: F) -> B
where
F: FnMut(&mut A, &mut A, &mut A) -> B,
{
if a == b || b == c || a == c {
panic!("vector::FocusMut::triplet: indices cannot be equal!");
}
let pa: *mut A = self.index_mut(a);
let pb: *mut A = self.index_mut(b);
let pc: *mut A = self.index_mut(c);
unsafe { f(&mut *pa, &mut *pb, &mut *pc) }
}
/// Get the chunk for the given index.
///
/// This gives you a reference to the leaf node that contains the index,
/// along with its start and end indices.
pub fn chunk_at(&mut self, index: usize) -> (Range<usize>, &mut [A]) {
let len = self.len();
if index >= len {
panic!("vector::FocusMut::chunk_at: index out of bounds");
}
match self {
FocusMut::Single(_, chunk) => (0..len, chunk),
FocusMut::Full(pool, tree) => {
let (range, chunk) = tree.get_chunk(pool, index);
(range, chunk)
}
}
}
}
impl<'a, A> IntoIterator for FocusMut<'a, A>
where
A: Clone + 'a,
{
type Item = &'a mut A;
type IntoIter = IterMut<'a, A>;
fn into_iter(self) -> Self::IntoIter {
IterMut::from_focus(self)
}
}
impl<'a, A> From<FocusMut<'a, A>> for Focus<'a, A>
where
A: Clone + 'a,
{
fn from(f: FocusMut<'a, A>) -> Focus<'a, A> {
f.unmut()
}
}
// NOTE: The documentation the mutable version is similar to the non-mutable version. I will comment for the places
// where there are differences, otherwise the documentation is copied directly.
pub struct TreeFocusMut<'a, A> {
/// The tree that this TreeFocusMut refers to. Unlike the non-mutable version, TreeFocusMut needs to store a
/// mutable reference. Additionally, there may be multiple TreeFocusMuts that refer to the same tree so we need a
/// Lock to synchronise the changes.
tree: Lock<&'a mut RRB<A>>,
/// The view represents the range of the tree that this TreeFocusMut can see. The view can be narrowed by calling
/// either the narrow or split_at methods.
view: Range<usize>,
/// The tree version of the Vector is represented as the concatenation of 2 chunks, followed by the tree root,
/// followed by 2 chunks. The middle_range refers to the range of the Vector that the tree covers.
middle_range: Range<usize>,
/// This implementation of a focusmut stores only a single chunk for the Vector. This chunk can refer to one of the
/// 4 chunks front/back chunks or one of the leaves of the tree. The target_ptr is the pointer to the actual chunk
/// in question. The target_range is the range that the chunk represents.
target_range: Range<usize>,
/// Not actually sure why this needs to be an atomic, it seems like it is unneccessary. This is just a pointer to
/// the chunk referred to above.
target_ptr: AtomicPtr<Chunk<A>>,
}
impl<'a, A> TreeFocusMut<'a, A>
where
A: 'a,
{
/// Creates a new TreeFocusMut for a Vector's RRB tree.
fn new(tree: &'a mut RRB<A>) -> Self {
let middle_start = tree.outer_f.len() + tree.inner_f.len();
let middle_end = middle_start + tree.middle.len();
TreeFocusMut {
view: 0..tree.length,
tree: Lock::new(tree),
middle_range: middle_start..middle_end,
target_range: 0..0,
target_ptr: AtomicPtr::default(),
}
}
/// Returns the number of elements that the TreeFocusMut is valid for.
fn len(&self) -> usize {
self.view.end - self.view.start
}
/// Restricts the TreeFocusMut to a subrange of itself.
fn narrow(self, mut view: Range<usize>) -> Self {
view.start += self.view.start;
view.end += self.view.start;
TreeFocusMut {
view,
middle_range: self.middle_range.clone(),
target_range: 0..0,
target_ptr: AtomicPtr::default(),
tree: self.tree,
}
}
/// Splits the TreeFocusMut into two disjoint foci. The first TreeFocusMut is valid for ..index while the
/// second is valid for index.. .
fn split_at(self, index: usize) -> (Self, Self) {
let len = self.len();
debug_assert!(index <= len);
let left = TreeFocusMut {
view: self.view.start..(self.view.start + index),
middle_range: self.middle_range.clone(),
target_range: 0..0,
target_ptr: AtomicPtr::default(),
tree: self.tree.clone(),
};
let right = TreeFocusMut {
view: (self.view.start + index)..(self.view.start + len),
middle_range: self.middle_range.clone(),
target_range: 0..0,
target_ptr: AtomicPtr::default(),
tree: self.tree,
};
(left, right)
}
/// Computes an absolute index in the RRBTree for the given index relative to the start of this TreeFocusMut.
fn physical_index(&self, index: usize) -> usize {
debug_assert!(index < self.view.end);
self.view.start + index
}
/// Computes a range relative to the TreeFocusMut given one that is absolute in the RRBTree.
fn logical_range(&self, range: &Range<usize>) -> Range<usize> {
(range.start - self.view.start)..(range.end - self.view.start)
}
/// Gets the chunk for an index and its corresponding range within the TreeFocusMut.
fn get_focus(&mut self) -> &mut Chunk<A> {
unsafe { &mut *self.target_ptr.load(Ordering::Relaxed) }
}
}
impl<'a, A> TreeFocusMut<'a, A>
where
A: Clone + 'a,
{
/// Sets the internal chunk to the one that contains the given absolute index.
fn set_focus(&mut self, pool: &RRBPool<A>, index: usize) {
let mut tree = self
.tree
.lock()
.expect("imbl::vector::Focus::set_focus: unable to acquire exclusive lock on Vector");
if index < self.middle_range.start {
let outer_len = tree.outer_f.len();
if index < outer_len {
self.target_range = 0..outer_len;
self.target_ptr.store(
PoolRef::make_mut(&pool.value_pool, &mut tree.outer_f),
Ordering::Relaxed,
);
} else {
self.target_range = outer_len..self.middle_range.start;
self.target_ptr.store(
PoolRef::make_mut(&pool.value_pool, &mut tree.inner_f),
Ordering::Relaxed,
);
}
} else if index >= self.middle_range.end {
let outer_start = self.middle_range.end + tree.inner_b.len();
if index < outer_start {
self.target_range = self.middle_range.end..outer_start;
self.target_ptr.store(
PoolRef::make_mut(&pool.value_pool, &mut tree.inner_b),
Ordering::Relaxed,
);
} else {
self.target_range = outer_start..tree.length;
self.target_ptr.store(
PoolRef::make_mut(&pool.value_pool, &mut tree.outer_b),
Ordering::Relaxed,
);
}
} else {
let tree_index = index - self.middle_range.start;
let level = tree.middle_level;
let middle = Ref::make_mut(&mut tree.middle);
let (range, ptr) = middle.lookup_chunk_mut(pool, level, 0, tree_index);
self.target_range =
(range.start + self.middle_range.start)..(range.end + self.middle_range.start);
self.target_ptr.store(ptr, Ordering::Relaxed);
}
}
/// Gets the value at the given index relative to the TreeFocusMut.
pub fn get(&mut self, pool: &RRBPool<A>, index: usize) -> Option<&mut A> {
if index >= self.len() {
return None;
}
let phys_index = self.physical_index(index);
if !contains(&self.target_range, &phys_index) {
self.set_focus(pool, phys_index);
}
let target_phys_index = phys_index - self.target_range.start;
Some(&mut self.get_focus()[target_phys_index])
}
/// Gets the chunk for an index as a slice and its corresponding range within the TreeFocusMut.
pub fn get_chunk(&mut self, pool: &RRBPool<A>, index: usize) -> (Range<usize>, &mut [A]) {
let phys_index = self.physical_index(index);
if !contains(&self.target_range, &phys_index) {
self.set_focus(pool, phys_index);
}
let mut left = 0;
let mut right = 0;
if self.target_range.start < self.view.start {
left = self.view.start - self.target_range.start;
}
if self.target_range.end > self.view.end {
right = self.target_range.end - self.view.end;
}
let phys_range = (self.target_range.start + left)..(self.target_range.end - right);
let log_range = self.logical_range(&phys_range);
let slice_len = self.get_focus().len();
let slice = &mut (self.get_focus().as_mut_slice())[left..(slice_len - right)];
(log_range, slice)
}
}