1 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT 2 // file at the top-level directory of this distribution and at 3 // http://rust-lang.org/COPYRIGHT. 4 // 5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or 6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license 7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your 8 // option. This file may not be copied, modified, or distributed 9 // except according to those terms. 10 11 //! A contiguous growable array type with heap-allocated contents, written 12 //! `Vec<'bump, T>`. 13 //! 14 //! Vectors have `O(1)` indexing, amortized `O(1)` push (to the end) and 15 //! `O(1)` pop (from the end). 16 //! 17 //! # Examples 18 //! 19 //! You can explicitly create a [`Vec<'bump, T>`] with [`new`]: 20 //! 21 //! ``` 22 //! use bumpalo::{Bump, collections::Vec}; 23 //! 24 //! let b = Bump::new(); 25 //! let v: Vec<i32> = Vec::new_in(&b); 26 //! ``` 27 //! 28 //! ...or by using the [`vec!`] macro: 29 //! 30 //! ``` 31 //! use bumpalo::{Bump, collections::Vec}; 32 //! 33 //! let b = Bump::new(); 34 //! 35 //! let v: Vec<i32> = bumpalo::vec![in &b]; 36 //! 37 //! let v = bumpalo::vec![in &b; 1, 2, 3, 4, 5]; 38 //! 39 //! let v = bumpalo::vec![in &b; 0; 10]; // ten zeroes 40 //! ``` 41 //! 42 //! You can [`push`] values onto the end of a vector (which will grow the vector 43 //! as needed): 44 //! 45 //! ``` 46 //! use bumpalo::{Bump, collections::Vec}; 47 //! 48 //! let b = Bump::new(); 49 //! 50 //! let mut v = bumpalo::vec![in &b; 1, 2]; 51 //! 52 //! v.push(3); 53 //! ``` 54 //! 55 //! Popping values works in much the same way: 56 //! 57 //! ``` 58 //! use bumpalo::{Bump, collections::Vec}; 59 //! 60 //! let b = Bump::new(); 61 //! 62 //! let mut v = bumpalo::vec![in &b; 1, 2]; 63 //! 64 //! let two = v.pop(); 65 //! ``` 66 //! 67 //! Vectors also support indexing (through the [`Index`] and [`IndexMut`] traits): 68 //! 69 //! ``` 70 //! use bumpalo::{Bump, collections::Vec}; 71 //! 72 //! let b = Bump::new(); 73 //! 74 //! let mut v = bumpalo::vec![in &b; 1, 2, 3]; 75 //! let three = v[2]; 76 //! v[1] = v[1] + 5; 77 //! ``` 78 //! 79 //! [`Vec<'bump, T>`]: ./struct.Vec.html 80 //! [`new`]: ./struct.Vec.html#method.new 81 //! [`push`]: ./struct.Vec.html#method.push 82 //! [`Index`]: https://doc.rust-lang.org/nightly/std/ops/trait.Index.html 83 //! [`IndexMut`]: ../../std/ops/trait.IndexMut.html 84 //! [`vec!`]: ../../macro.vec.html 85 86 use super::raw_vec::RawVec; 87 use crate::Bump; 88 use core::cmp::Ordering; 89 use core::fmt; 90 use core::hash::{self, Hash}; 91 use core::iter::FusedIterator; 92 use core::marker::PhantomData; 93 use core::mem; 94 use core::ops; 95 use core::ops::Bound::{Excluded, Included, Unbounded}; 96 use core::ops::{Index, IndexMut, RangeBounds}; 97 use core::ptr; 98 use core::ptr::NonNull; 99 use core::slice; 100 101 unsafe fn arith_offset<T>(p: *const T, offset: isize) -> *const T { 102 p.offset(offset) 103 } 104 105 fn partition_dedup_by<T, F>(s: &mut [T], mut same_bucket: F) -> (&mut [T], &mut [T]) 106 where 107 F: FnMut(&mut T, &mut T) -> bool, 108 { 109 // Although we have a mutable reference to `s`, we cannot make 110 // *arbitrary* changes. The `same_bucket` calls could panic, so we 111 // must ensure that the slice is in a valid state at all times. 112 // 113 // The way that we handle this is by using swaps; we iterate 114 // over all the elements, swapping as we go so that at the end 115 // the elements we wish to keep are in the front, and those we 116 // wish to reject are at the back. We can then split the slice. 117 // This operation is still O(n). 118 // 119 // Example: We start in this state, where `r` represents "next 120 // read" and `w` represents "next_write`. 121 // 122 // r 123 // +---+---+---+---+---+---+ 124 // | 0 | 1 | 1 | 2 | 3 | 3 | 125 // +---+---+---+---+---+---+ 126 // w 127 // 128 // Comparing s[r] against s[w-1], this is not a duplicate, so 129 // we swap s[r] and s[w] (no effect as r==w) and then increment both 130 // r and w, leaving us with: 131 // 132 // r 133 // +---+---+---+---+---+---+ 134 // | 0 | 1 | 1 | 2 | 3 | 3 | 135 // +---+---+---+---+---+---+ 136 // w 137 // 138 // Comparing s[r] against s[w-1], this value is a duplicate, 139 // so we increment `r` but leave everything else unchanged: 140 // 141 // r 142 // +---+---+---+---+---+---+ 143 // | 0 | 1 | 1 | 2 | 3 | 3 | 144 // +---+---+---+---+---+---+ 145 // w 146 // 147 // Comparing s[r] against s[w-1], this is not a duplicate, 148 // so swap s[r] and s[w] and advance r and w: 149 // 150 // r 151 // +---+---+---+---+---+---+ 152 // | 0 | 1 | 2 | 1 | 3 | 3 | 153 // +---+---+---+---+---+---+ 154 // w 155 // 156 // Not a duplicate, repeat: 157 // 158 // r 159 // +---+---+---+---+---+---+ 160 // | 0 | 1 | 2 | 3 | 1 | 3 | 161 // +---+---+---+---+---+---+ 162 // w 163 // 164 // Duplicate, advance r. End of slice. Split at w. 165 166 let len = s.len(); 167 if len <= 1 { 168 return (s, &mut []); 169 } 170 171 let ptr = s.as_mut_ptr(); 172 let mut next_read: usize = 1; 173 let mut next_write: usize = 1; 174 175 unsafe { 176 // Avoid bounds checks by using raw pointers. 177 while next_read < len { 178 let ptr_read = ptr.add(next_read); 179 let prev_ptr_write = ptr.add(next_write - 1); 180 if !same_bucket(&mut *ptr_read, &mut *prev_ptr_write) { 181 if next_read != next_write { 182 let ptr_write = prev_ptr_write.offset(1); 183 mem::swap(&mut *ptr_read, &mut *ptr_write); 184 } 185 next_write += 1; 186 } 187 next_read += 1; 188 } 189 } 190 191 s.split_at_mut(next_write) 192 } 193 194 unsafe fn offset_from<T>(p: *const T, origin: *const T) -> isize 195 where 196 T: Sized, 197 { 198 let pointee_size = mem::size_of::<T>(); 199 assert!(0 < pointee_size && pointee_size <= isize::max_value() as usize); 200 201 // This is the same sequence that Clang emits for pointer subtraction. 202 // It can be neither `nsw` nor `nuw` because the input is treated as 203 // unsigned but then the output is treated as signed, so neither works. 204 let d = isize::wrapping_sub(p as _, origin as _); 205 d / (pointee_size as isize) 206 } 207 208 /// Creates a [`Vec`] containing the arguments. 209 /// 210 /// `vec!` allows `Vec`s to be defined with the same syntax as array expressions. 211 /// There are two forms of this macro: 212 /// 213 /// - Create a [`Vec`] containing a given list of elements: 214 /// 215 /// ``` 216 /// use bumpalo::{Bump, vec}; 217 /// 218 /// let b = Bump::new(); 219 /// let v = bumpalo::vec![in &b; 1, 2, 3]; 220 /// assert_eq!(v[0], 1); 221 /// assert_eq!(v[1], 2); 222 /// assert_eq!(v[2], 3); 223 /// ``` 224 /// 225 /// - Create a [`Vec`] from a given element and size: 226 /// 227 /// ``` 228 /// use bumpalo::{Bump, vec}; 229 /// 230 /// let b = Bump::new(); 231 /// let v = bumpalo::vec![in &b; 1; 3]; 232 /// assert_eq!(v, [1, 1, 1]); 233 /// ``` 234 /// 235 /// Note that unlike array expressions this syntax supports all elements 236 /// which implement [`Clone`] and the number of elements doesn't have to be 237 /// a constant. 238 /// 239 /// This will use `clone` to duplicate an expression, so one should be careful 240 /// using this with types having a nonstandard `Clone` implementation. For 241 /// example, `bumpalo::vec![in ≎ Rc::new(1); 5]` will create a vector of five references 242 /// to the same boxed integer value, not five references pointing to independently 243 /// boxed integers. 244 /// 245 /// [`Vec`]: ../collections/vec/struct.Vec.html 246 /// [`Clone`]: https://doc.rust-lang.org/nightly/std/clone/trait.Clone.html 247 #[macro_export] 248 macro_rules! vec { 249 (in $bump:expr; $elem:expr; $n:expr) => {{ 250 let n = $n; 251 let mut v = $crate::collections::Vec::with_capacity_in(n, $bump); 252 if n > 0 { 253 let elem = $elem; 254 for _ in 0..n - 1 { 255 v.push(elem.clone()); 256 } 257 v.push(elem); 258 } 259 v 260 }}; 261 (in $bump:expr) => { $crate::collections::Vec::new_in($bump) }; 262 (in $bump:expr; $($x:expr),*) => {{ 263 let mut v = $crate::collections::Vec::new_in($bump); 264 $( v.push($x); )* 265 v 266 }}; 267 (in $bump:expr; $($x:expr,)*) => (bumpalo::vec![in $bump; $($x),*]) 268 } 269 270 /// A contiguous growable array type, written `Vec<'bump, T>` but pronounced 'vector'. 271 /// 272 /// # Examples 273 /// 274 /// ``` 275 /// use bumpalo::{Bump, collections::Vec}; 276 /// 277 /// let b = Bump::new(); 278 /// 279 /// let mut vec = Vec::new_in(&b); 280 /// vec.push(1); 281 /// vec.push(2); 282 /// 283 /// assert_eq!(vec.len(), 2); 284 /// assert_eq!(vec[0], 1); 285 /// 286 /// assert_eq!(vec.pop(), Some(2)); 287 /// assert_eq!(vec.len(), 1); 288 /// 289 /// vec[0] = 7; 290 /// assert_eq!(vec[0], 7); 291 /// 292 /// vec.extend([1, 2, 3].iter().cloned()); 293 /// 294 /// for x in &vec { 295 /// println!("{}", x); 296 /// } 297 /// assert_eq!(vec, [7, 1, 2, 3]); 298 /// ``` 299 /// 300 /// The [`vec!`] macro is provided to make initialization more convenient: 301 /// 302 /// ``` 303 /// use bumpalo::{Bump, collections::Vec}; 304 /// 305 /// let b = Bump::new(); 306 /// 307 /// let mut vec = bumpalo::vec![in &b; 1, 2, 3]; 308 /// vec.push(4); 309 /// assert_eq!(vec, [1, 2, 3, 4]); 310 /// ``` 311 /// 312 /// It can also initialize each element of a `Vec<'bump, T>` with a given value. 313 /// This may be more efficient than performing allocation and initialization 314 /// in separate steps, especially when initializing a vector of zeros: 315 /// 316 /// ``` 317 /// use bumpalo::{Bump, collections::Vec}; 318 /// 319 /// let b = Bump::new(); 320 /// 321 /// let vec = bumpalo::vec![in &b; 0; 5]; 322 /// assert_eq!(vec, [0, 0, 0, 0, 0]); 323 /// 324 /// // The following is equivalent, but potentially slower: 325 /// let mut vec1 = Vec::with_capacity_in(5, &b); 326 /// vec1.resize(5, 0); 327 /// ``` 328 /// 329 /// Use a `Vec<'bump, T>` as an efficient stack: 330 /// 331 /// ``` 332 /// use bumpalo::{Bump, collections::Vec}; 333 /// 334 /// let b = Bump::new(); 335 /// 336 /// let mut stack = Vec::new_in(&b); 337 /// 338 /// stack.push(1); 339 /// stack.push(2); 340 /// stack.push(3); 341 /// 342 /// while let Some(top) = stack.pop() { 343 /// // Prints 3, 2, 1 344 /// println!("{}", top); 345 /// } 346 /// ``` 347 /// 348 /// # Indexing 349 /// 350 /// The `Vec` type allows to access values by index, because it implements the 351 /// [`Index`] trait. An example will be more explicit: 352 /// 353 /// ``` 354 /// use bumpalo::{Bump, collections::Vec}; 355 /// 356 /// let b = Bump::new(); 357 /// 358 /// let v = bumpalo::vec![in &b; 0, 2, 4, 6]; 359 /// println!("{}", v[1]); // it will display '2' 360 /// ``` 361 /// 362 /// However be careful: if you try to access an index which isn't in the `Vec`, 363 /// your software will panic! You cannot do this: 364 /// 365 /// ```should_panic 366 /// use bumpalo::{Bump, collections::Vec}; 367 /// 368 /// let b = Bump::new(); 369 /// 370 /// let v = bumpalo::vec![in &b; 0, 2, 4, 6]; 371 /// println!("{}", v[6]); // it will panic! 372 /// ``` 373 /// 374 /// In conclusion: always check if the index you want to get really exists 375 /// before doing it. 376 /// 377 /// # Slicing 378 /// 379 /// A `Vec` can be mutable. Slices, on the other hand, are read-only objects. 380 /// To get a slice, use `&`. Example: 381 /// 382 /// ``` 383 /// use bumpalo::{Bump, collections::Vec}; 384 /// 385 /// fn read_slice(slice: &[usize]) { 386 /// // ... 387 /// } 388 /// 389 /// let b = Bump::new(); 390 /// 391 /// let v = bumpalo::vec![in &b; 0, 1]; 392 /// read_slice(&v); 393 /// 394 /// // ... and that's all! 395 /// // you can also do it like this: 396 /// let x : &[usize] = &v; 397 /// ``` 398 /// 399 /// In Rust, it's more common to pass slices as arguments rather than vectors 400 /// when you just want to provide a read access. The same goes for [`String`] and 401 /// [`&str`]. 402 /// 403 /// # Capacity and reallocation 404 /// 405 /// The capacity of a vector is the amount of space allocated for any future 406 /// elements that will be added onto the vector. This is not to be confused with 407 /// the *length* of a vector, which specifies the number of actual elements 408 /// within the vector. If a vector's length exceeds its capacity, its capacity 409 /// will automatically be increased, but its elements will have to be 410 /// reallocated. 411 /// 412 /// For example, a vector with capacity 10 and length 0 would be an empty vector 413 /// with space for 10 more elements. Pushing 10 or fewer elements onto the 414 /// vector will not change its capacity or cause reallocation to occur. However, 415 /// if the vector's length is increased to 11, it will have to reallocate, which 416 /// can be slow. For this reason, it is recommended to use [`Vec::with_capacity_in`] 417 /// whenever possible to specify how big the vector is expected to get. 418 /// 419 /// # Guarantees 420 /// 421 /// Due to its incredibly fundamental nature, `Vec` makes a lot of guarantees 422 /// about its design. This ensures that it's as low-overhead as possible in 423 /// the general case, and can be correctly manipulated in primitive ways 424 /// by unsafe code. Note that these guarantees refer to an unqualified `Vec<'bump, T>`. 425 /// If additional type parameters are added (e.g. to support custom allocators), 426 /// overriding their defaults may change the behavior. 427 /// 428 /// Most fundamentally, `Vec` is and always will be a (pointer, capacity, length) 429 /// triplet. No more, no less. The order of these fields is completely 430 /// unspecified, and you should use the appropriate methods to modify these. 431 /// The pointer will never be null, so this type is null-pointer-optimized. 432 /// 433 /// However, the pointer may not actually point to allocated memory. In particular, 434 /// if you construct a `Vec` with capacity 0 via [`Vec::new_in`], [`bumpalo::vec![in bump]`][`vec!`], 435 /// [`Vec::with_capacity_in(0)`][`Vec::with_capacity_in`], or by calling [`shrink_to_fit`] 436 /// on an empty Vec, it will not allocate memory. Similarly, if you store zero-sized 437 /// types inside a `Vec`, it will not allocate space for them. *Note that in this case 438 /// the `Vec` may not report a [`capacity`] of 0*. `Vec` will allocate if and only 439 /// if [`mem::size_of::<T>`]`() * capacity() > 0`. In general, `Vec`'s allocation 440 /// details are very subtle — if you intend to allocate memory using a `Vec` 441 /// and use it for something else (either to pass to unsafe code, or to build your 442 /// own memory-backed collection), be sure to deallocate this memory by using 443 /// `from_raw_parts` to recover the `Vec` and then dropping it. 444 /// 445 /// If a `Vec` *has* allocated memory, then the memory it points to is on the heap 446 /// (as defined by the allocator Rust is configured to use by default), and its 447 /// pointer points to [`len`] initialized, contiguous elements in order (what 448 /// you would see if you coerced it to a slice), followed by [`capacity`]` - 449 /// `[`len`] logically uninitialized, contiguous elements. 450 /// 451 /// `Vec` will never perform a "small optimization" where elements are actually 452 /// stored on the stack for two reasons: 453 /// 454 /// * It would make it more difficult for unsafe code to correctly manipulate 455 /// a `Vec`. The contents of a `Vec` wouldn't have a stable address if it were 456 /// only moved, and it would be more difficult to determine if a `Vec` had 457 /// actually allocated memory. 458 /// 459 /// * It would penalize the general case, incurring an additional branch 460 /// on every access. 461 /// 462 /// `Vec` will never automatically shrink itself, even if completely empty. This 463 /// ensures no unnecessary allocations or deallocations occur. Emptying a `Vec` 464 /// and then filling it back up to the same [`len`] should incur no calls to 465 /// the allocator. If you wish to free up unused memory, use 466 /// [`shrink_to_fit`][`shrink_to_fit`]. 467 /// 468 /// [`push`] and [`insert`] will never (re)allocate if the reported capacity is 469 /// sufficient. [`push`] and [`insert`] *will* (re)allocate if 470 /// [`len`]` == `[`capacity`]. That is, the reported capacity is completely 471 /// accurate, and can be relied on. It can even be used to manually free the memory 472 /// allocated by a `Vec` if desired. Bulk insertion methods *may* reallocate, even 473 /// when not necessary. 474 /// 475 /// `Vec` does not guarantee any particular growth strategy when reallocating 476 /// when full, nor when [`reserve`] is called. The current strategy is basic 477 /// and it may prove desirable to use a non-constant growth factor. Whatever 478 /// strategy is used will of course guarantee `O(1)` amortized [`push`]. 479 /// 480 /// `bumpalo::vec![in bump; x; n]`, `bumpalo::vec![in bump; a, b, c, d]`, and 481 /// [`Vec::with_capacity_in(n)`][`Vec::with_capacity_in`], will all produce a 482 /// `Vec` with exactly the requested capacity. If [`len`]` == `[`capacity`], (as 483 /// is the case for the [`vec!`] macro), then a `Vec<'bump, T>` can be converted 484 /// to and from a [`Box<[T]>`][owned slice] without reallocating or moving the 485 /// elements. 486 /// 487 /// `Vec` will not specifically overwrite any data that is removed from it, 488 /// but also won't specifically preserve it. Its uninitialized memory is 489 /// scratch space that it may use however it wants. It will generally just do 490 /// whatever is most efficient or otherwise easy to implement. Do not rely on 491 /// removed data to be erased for security purposes. Even if you drop a `Vec`, its 492 /// buffer may simply be reused by another `Vec`. Even if you zero a `Vec`'s memory 493 /// first, that may not actually happen because the optimizer does not consider 494 /// this a side-effect that must be preserved. There is one case which we will 495 /// not break, however: using `unsafe` code to write to the excess capacity, 496 /// and then increasing the length to match, is always valid. 497 /// 498 /// `Vec` does not currently guarantee the order in which elements are dropped. 499 /// The order has changed in the past and may change again. 500 /// 501 /// [`vec!`]: ../../macro.vec.html 502 /// [`Index`]: https://doc.rust-lang.org/nightly/std/ops/trait.Index.html 503 /// [`String`]: https://doc.rust-lang.org/nightly/std/string/struct.String.html 504 /// [`&str`]: https://doc.rust-lang.org/nightly/std/primitive.str.html 505 /// [`Vec::with_capacity_in`]: ./struct.Vec.html#method.with_capacity_in 506 /// [`Vec::new_in`]: ./struct.Vec.html#method.new 507 /// [`shrink_to_fit`]: ./struct.Vec.html#method.shrink_to_fit 508 /// [`capacity`]: ./struct.Vec.html#method.capacity 509 /// [`mem::size_of::<T>`]: https://doc.rust-lang.org/nightly/std/mem/fn.size_of.html 510 /// [`len`]: ./struct.Vec.html#method.len 511 /// [`push`]: ./struct.Vec.html#method.push 512 /// [`insert`]: ./struct.Vec.html#method.insert 513 /// [`reserve`]: ./struct.Vec.html#method.reserve 514 /// [owned slice]: https://doc.rust-lang.org/nightly/std/boxed/struct.Box.html 515 pub struct Vec<'bump, T: 'bump> { 516 buf: RawVec<'bump, T>, 517 len: usize, 518 } 519 520 //////////////////////////////////////////////////////////////////////////////// 521 // Inherent methods 522 //////////////////////////////////////////////////////////////////////////////// 523 524 impl<'bump, T: 'bump> Vec<'bump, T> { 525 /// Constructs a new, empty `Vec<'bump, T>`. 526 /// 527 /// The vector will not allocate until elements are pushed onto it. 528 /// 529 /// # Examples 530 /// 531 /// ``` 532 /// # #![allow(unused_mut)] 533 /// use bumpalo::{Bump, collections::Vec}; 534 /// 535 /// let b = Bump::new(); 536 /// let mut vec: Vec<i32> = Vec::new_in(&b); 537 /// ``` 538 #[inline] 539 pub fn new_in(bump: &'bump Bump) -> Vec<'bump, T> { 540 Vec { 541 buf: RawVec::new_in(bump), 542 len: 0, 543 } 544 } 545 546 /// Constructs a new, empty `Vec<'bump, T>` with the specified capacity. 547 /// 548 /// The vector will be able to hold exactly `capacity` elements without 549 /// reallocating. If `capacity` is 0, the vector will not allocate. 550 /// 551 /// It is important to note that although the returned vector has the 552 /// *capacity* specified, the vector will have a zero *length*. For an 553 /// explanation of the difference between length and capacity, see 554 /// *[Capacity and reallocation]*. 555 /// 556 /// [Capacity and reallocation]: #capacity-and-reallocation 557 /// 558 /// # Examples 559 /// 560 /// ``` 561 /// use bumpalo::{Bump, collections::Vec}; 562 /// 563 /// let b = Bump::new(); 564 /// 565 /// let mut vec = Vec::with_capacity_in(10, &b); 566 /// 567 /// // The vector contains no items, even though it has capacity for more 568 /// assert_eq!(vec.len(), 0); 569 /// 570 /// // These are all done without reallocating... 571 /// for i in 0..10 { 572 /// vec.push(i); 573 /// } 574 /// 575 /// // ...but this may make the vector reallocate 576 /// vec.push(11); 577 /// ``` 578 #[inline] 579 pub fn with_capacity_in(capacity: usize, bump: &'bump Bump) -> Vec<'bump, T> { 580 Vec { 581 buf: RawVec::with_capacity_in(capacity, bump), 582 len: 0, 583 } 584 } 585 586 /// Construct a new `Vec` from the given iterator's items. 587 /// 588 /// # Examples 589 /// 590 /// ``` 591 /// use bumpalo::{Bump, collections::Vec}; 592 /// use std::iter; 593 /// 594 /// let b = Bump::new(); 595 /// let v = Vec::from_iter_in(iter::repeat(7).take(3), &b); 596 /// assert_eq!(v, [7, 7, 7]); 597 /// ``` 598 pub fn from_iter_in<I: IntoIterator<Item = T>>(iter: I, bump: &'bump Bump) -> Vec<'bump, T> { 599 let mut v = Vec::new_in(bump); 600 v.extend(iter); 601 v 602 } 603 604 /// Creates a `Vec<'bump, T>` directly from the raw components of another vector. 605 /// 606 /// # Safety 607 /// 608 /// This is highly unsafe, due to the number of invariants that aren't 609 /// checked: 610 /// 611 /// * `ptr` needs to have been previously allocated via [`String`]/`Vec<'bump, T>` 612 /// (at least, it's highly likely to be incorrect if it wasn't). 613 /// * `ptr`'s `T` needs to have the same size and alignment as it was allocated with. 614 /// * `length` needs to be less than or equal to `capacity`. 615 /// * `capacity` needs to be the capacity that the pointer was allocated with. 616 /// 617 /// Violating these may cause problems like corrupting the allocator's 618 /// internal data structures. For example it is **not** safe 619 /// to build a `Vec<u8>` from a pointer to a C `char` array and a `size_t`. 620 /// 621 /// The ownership of `ptr` is effectively transferred to the 622 /// `Vec<'bump, T>` which may then deallocate, reallocate or change the 623 /// contents of memory pointed to by the pointer at will. Ensure 624 /// that nothing else uses the pointer after calling this 625 /// function. 626 /// 627 /// [`String`]: https://doc.rust-lang.org/nightly/std/string/struct.String.html 628 /// 629 /// # Examples 630 /// 631 /// ``` 632 /// use bumpalo::{Bump, collections::Vec}; 633 /// 634 /// use std::ptr; 635 /// use std::mem; 636 /// 637 /// let b = Bump::new(); 638 /// 639 /// let mut v = bumpalo::vec![in &b; 1, 2, 3]; 640 /// 641 /// // Pull out the various important pieces of information about `v` 642 /// let p = v.as_mut_ptr(); 643 /// let len = v.len(); 644 /// let cap = v.capacity(); 645 /// 646 /// unsafe { 647 /// // Cast `v` into the void: no destructor run, so we are in 648 /// // complete control of the allocation to which `p` points. 649 /// mem::forget(v); 650 /// 651 /// // Overwrite memory with 4, 5, 6 652 /// for i in 0..len as isize { 653 /// ptr::write(p.offset(i), 4 + i); 654 /// } 655 /// 656 /// // Put everything back together into a Vec 657 /// let rebuilt = Vec::from_raw_parts_in(p, len, cap, &b); 658 /// assert_eq!(rebuilt, [4, 5, 6]); 659 /// } 660 /// ``` 661 pub unsafe fn from_raw_parts_in( 662 ptr: *mut T, 663 length: usize, 664 capacity: usize, 665 bump: &'bump Bump, 666 ) -> Vec<'bump, T> { 667 Vec { 668 buf: RawVec::from_raw_parts_in(ptr, capacity, bump), 669 len: length, 670 } 671 } 672 673 /// Returns the number of elements the vector can hold without 674 /// reallocating. 675 /// 676 /// # Examples 677 /// 678 /// ``` 679 /// use bumpalo::{Bump, collections::Vec}; 680 /// 681 /// let b = Bump::new(); 682 /// let vec: Vec<i32> = Vec::with_capacity_in(10, &b); 683 /// assert_eq!(vec.capacity(), 10); 684 /// ``` 685 #[inline] 686 pub fn capacity(&self) -> usize { 687 self.buf.cap() 688 } 689 690 /// Reserves capacity for at least `additional` more elements to be inserted 691 /// in the given `Vec<'bump, T>`. The collection may reserve more space to avoid 692 /// frequent reallocations. After calling `reserve`, capacity will be 693 /// greater than or equal to `self.len() + additional`. Does nothing if 694 /// capacity is already sufficient. 695 /// 696 /// # Panics 697 /// 698 /// Panics if the new capacity overflows `usize`. 699 /// 700 /// # Examples 701 /// 702 /// ``` 703 /// use bumpalo::{Bump, collections::Vec}; 704 /// 705 /// let b = Bump::new(); 706 /// let mut vec = bumpalo::vec![in &b; 1]; 707 /// vec.reserve(10); 708 /// assert!(vec.capacity() >= 11); 709 /// ``` 710 pub fn reserve(&mut self, additional: usize) { 711 self.buf.reserve(self.len, additional); 712 } 713 714 /// Reserves the minimum capacity for exactly `additional` more elements to 715 /// be inserted in the given `Vec<'bump, T>`. After calling `reserve_exact`, 716 /// capacity will be greater than or equal to `self.len() + additional`. 717 /// Does nothing if the capacity is already sufficient. 718 /// 719 /// Note that the allocator may give the collection more space than it 720 /// requests. Therefore capacity can not be relied upon to be precisely 721 /// minimal. Prefer `reserve` if future insertions are expected. 722 /// 723 /// # Panics 724 /// 725 /// Panics if the new capacity overflows `usize`. 726 /// 727 /// # Examples 728 /// 729 /// ``` 730 /// use bumpalo::{Bump, collections::Vec}; 731 /// 732 /// let b = Bump::new(); 733 /// let mut vec = bumpalo::vec![in &b; 1]; 734 /// vec.reserve_exact(10); 735 /// assert!(vec.capacity() >= 11); 736 /// ``` 737 pub fn reserve_exact(&mut self, additional: usize) { 738 self.buf.reserve_exact(self.len, additional); 739 } 740 741 /// Shrinks the capacity of the vector as much as possible. 742 /// 743 /// It will drop down as close as possible to the length but the allocator 744 /// may still inform the vector that there is space for a few more elements. 745 /// 746 /// # Examples 747 /// 748 /// ``` 749 /// use bumpalo::{Bump, collections::Vec}; 750 /// 751 /// let b = Bump::new(); 752 /// 753 /// let mut vec = Vec::with_capacity_in(10, &b); 754 /// vec.extend([1, 2, 3].iter().cloned()); 755 /// assert_eq!(vec.capacity(), 10); 756 /// vec.shrink_to_fit(); 757 /// assert!(vec.capacity() >= 3); 758 /// ``` 759 pub fn shrink_to_fit(&mut self) { 760 if self.capacity() != self.len { 761 self.buf.shrink_to_fit(self.len); 762 } 763 } 764 765 /// Converts the vector into `&'bump [T]`. 766 /// 767 /// # Examples 768 /// 769 /// ``` 770 /// use bumpalo::{Bump, collections::Vec}; 771 /// 772 /// let b = Bump::new(); 773 /// let v = bumpalo::vec![in &b; 1, 2, 3]; 774 /// 775 /// let slice = v.into_bump_slice(); 776 /// assert_eq!(slice, [1, 2, 3]); 777 /// ``` 778 pub fn into_bump_slice(self) -> &'bump [T] { 779 unsafe { 780 let ptr = self.as_ptr(); 781 let len = self.len(); 782 mem::forget(self); 783 slice::from_raw_parts(ptr, len) 784 } 785 } 786 787 /// Converts the vector into `&'bump mut [T]`. 788 /// 789 /// # Examples 790 /// 791 /// ``` 792 /// use bumpalo::{Bump, collections::Vec}; 793 /// 794 /// let b = Bump::new(); 795 /// let v = bumpalo::vec![in &b; 1, 2, 3]; 796 /// 797 /// let mut slice = v.into_bump_slice_mut(); 798 /// 799 /// slice[0] = 3; 800 /// slice[2] = 1; 801 /// 802 /// assert_eq!(slice, [3, 2, 1]); 803 /// ``` 804 pub fn into_bump_slice_mut(mut self) -> &'bump mut [T] { 805 let ptr = self.as_mut_ptr(); 806 let len = self.len(); 807 mem::forget(self); 808 809 unsafe { 810 slice::from_raw_parts_mut(ptr, len) 811 } 812 } 813 814 /// Shortens the vector, keeping the first `len` elements and dropping 815 /// the rest. 816 /// 817 /// If `len` is greater than the vector's current length, this has no 818 /// effect. 819 /// 820 /// The [`drain`] method can emulate `truncate`, but causes the excess 821 /// elements to be returned instead of dropped. 822 /// 823 /// Note that this method has no effect on the allocated capacity 824 /// of the vector. 825 /// 826 /// # Examples 827 /// 828 /// Truncating a five element vector to two elements: 829 /// 830 /// ``` 831 /// use bumpalo::{Bump, collections::Vec}; 832 /// 833 /// let b = Bump::new(); 834 /// 835 /// let mut vec = bumpalo::vec![in &b; 1, 2, 3, 4, 5]; 836 /// vec.truncate(2); 837 /// assert_eq!(vec, [1, 2]); 838 /// ``` 839 /// 840 /// No truncation occurs when `len` is greater than the vector's current 841 /// length: 842 /// 843 /// ``` 844 /// use bumpalo::{Bump, collections::Vec}; 845 /// 846 /// let b = Bump::new(); 847 /// 848 /// let mut vec = bumpalo::vec![in &b; 1, 2, 3]; 849 /// vec.truncate(8); 850 /// assert_eq!(vec, [1, 2, 3]); 851 /// ``` 852 /// 853 /// Truncating when `len == 0` is equivalent to calling the [`clear`] 854 /// method. 855 /// 856 /// ``` 857 /// use bumpalo::{Bump, collections::Vec}; 858 /// 859 /// let b = Bump::new(); 860 /// 861 /// let mut vec = bumpalo::vec![in &b; 1, 2, 3]; 862 /// vec.truncate(0); 863 /// assert_eq!(vec, []); 864 /// ``` 865 /// 866 /// [`clear`]: #method.clear 867 /// [`drain`]: #method.drain 868 pub fn truncate(&mut self, len: usize) { 869 let current_len = self.len; 870 unsafe { 871 let mut ptr = self.as_mut_ptr().add(self.len); 872 // Set the final length at the end, keeping in mind that 873 // dropping an element might panic. Works around a missed 874 // optimization, as seen in the following issue: 875 // https://github.com/rust-lang/rust/issues/51802 876 let mut local_len = SetLenOnDrop::new(&mut self.len); 877 878 // drop any extra elements 879 for _ in len..current_len { 880 local_len.decrement_len(1); 881 ptr = ptr.offset(-1); 882 ptr::drop_in_place(ptr); 883 } 884 } 885 } 886 887 /// Extracts a slice containing the entire vector. 888 /// 889 /// Equivalent to `&s[..]`. 890 /// 891 /// # Examples 892 /// 893 /// ``` 894 /// use bumpalo::{Bump, collections::Vec}; 895 /// use std::io::{self, Write}; 896 /// 897 /// let b = Bump::new(); 898 /// 899 /// let buffer = bumpalo::vec![in &b; 1, 2, 3, 5, 8]; 900 /// io::sink().write(buffer.as_slice()).unwrap(); 901 /// ``` 902 #[inline] 903 pub fn as_slice(&self) -> &[T] { 904 self 905 } 906 907 /// Extracts a mutable slice of the entire vector. 908 /// 909 /// Equivalent to `&mut s[..]`. 910 /// 911 /// # Examples 912 /// 913 /// ``` 914 /// use bumpalo::{Bump, collections::Vec}; 915 /// use std::io::{self, Read}; 916 /// 917 /// let b = Bump::new(); 918 /// let mut buffer = bumpalo::vec![in &b; 0; 3]; 919 /// io::repeat(0b101).read_exact(buffer.as_mut_slice()).unwrap(); 920 /// ``` 921 #[inline] 922 pub fn as_mut_slice(&mut self) -> &mut [T] { 923 self 924 } 925 926 /// Sets the length of a vector. 927 /// 928 /// This will explicitly set the size of the vector, without actually 929 /// modifying its buffers, so it is up to the caller to ensure that the 930 /// vector is actually the specified size. 931 /// 932 /// # Safety 933 /// 934 /// - `new_len` must be less than or equal to [`capacity()`]. 935 /// - The elements at `old_len..new_len` must be initialized. 936 /// 937 /// # Examples 938 /// 939 /// ``` 940 /// use bumpalo::{Bump, collections::Vec}; 941 /// 942 /// use std::ptr; 943 /// 944 /// let b = Bump::new(); 945 /// 946 /// let mut vec = bumpalo::vec![in &b; 'r', 'u', 's', 't']; 947 /// 948 /// unsafe { 949 /// ptr::drop_in_place(&mut vec[3]); 950 /// vec.set_len(3); 951 /// } 952 /// assert_eq!(vec, ['r', 'u', 's']); 953 /// ``` 954 /// 955 /// In this example, there is a memory leak since the memory locations 956 /// owned by the inner vectors were not freed prior to the `set_len` call: 957 /// 958 /// ``` 959 /// use bumpalo::{Bump, collections::Vec}; 960 /// 961 /// let b = Bump::new(); 962 /// 963 /// let mut vec = bumpalo::vec![in &b; 964 /// bumpalo::vec![in &b; 1, 0, 0], 965 /// bumpalo::vec![in &b; 0, 1, 0], 966 /// bumpalo::vec![in &b; 0, 0, 1]]; 967 /// unsafe { 968 /// vec.set_len(0); 969 /// } 970 /// ``` 971 /// 972 /// In this example, the vector gets expanded from zero to four items 973 /// without any memory allocations occurring, resulting in vector 974 /// values of unallocated memory: 975 /// 976 /// ``` 977 /// use bumpalo::{Bump, collections::Vec}; 978 /// 979 /// let b = Bump::new(); 980 /// 981 /// let mut vec: Vec<char> = Vec::new_in(&b); 982 /// 983 /// unsafe { 984 /// vec.set_len(4); 985 /// } 986 /// ``` 987 #[inline] 988 pub unsafe fn set_len(&mut self, new_len: usize) { 989 self.len = new_len; 990 } 991 992 /// Removes an element from the vector and returns it. 993 /// 994 /// The removed element is replaced by the last element of the vector. 995 /// 996 /// This does not preserve ordering, but is O(1). 997 /// 998 /// # Panics 999 /// 1000 /// Panics if `index` is out of bounds. 1001 /// 1002 /// # Examples 1003 /// 1004 /// ``` 1005 /// use bumpalo::{Bump, collections::Vec}; 1006 /// 1007 /// let b = Bump::new(); 1008 /// 1009 /// let mut v = bumpalo::vec![in &b; "foo", "bar", "baz", "qux"]; 1010 /// 1011 /// assert_eq!(v.swap_remove(1), "bar"); 1012 /// assert_eq!(v, ["foo", "qux", "baz"]); 1013 /// 1014 /// assert_eq!(v.swap_remove(0), "foo"); 1015 /// assert_eq!(v, ["baz", "qux"]); 1016 /// ``` 1017 #[inline] 1018 pub fn swap_remove(&mut self, index: usize) -> T { 1019 unsafe { 1020 // We replace self[index] with the last element. Note that if the 1021 // bounds check on hole succeeds there must be a last element (which 1022 // can be self[index] itself). 1023 let hole: *mut T = &mut self[index]; 1024 let last = ptr::read(self.get_unchecked(self.len - 1)); 1025 self.len -= 1; 1026 ptr::replace(hole, last) 1027 } 1028 } 1029 1030 /// Inserts an element at position `index` within the vector, shifting all 1031 /// elements after it to the right. 1032 /// 1033 /// # Panics 1034 /// 1035 /// Panics if `index > len`. 1036 /// 1037 /// # Examples 1038 /// 1039 /// ``` 1040 /// use bumpalo::{Bump, collections::Vec}; 1041 /// 1042 /// let b = Bump::new(); 1043 /// 1044 /// let mut vec = bumpalo::vec![in &b; 1, 2, 3]; 1045 /// vec.insert(1, 4); 1046 /// assert_eq!(vec, [1, 4, 2, 3]); 1047 /// vec.insert(4, 5); 1048 /// assert_eq!(vec, [1, 4, 2, 3, 5]); 1049 /// ``` 1050 pub fn insert(&mut self, index: usize, element: T) { 1051 let len = self.len(); 1052 assert!(index <= len); 1053 1054 // space for the new element 1055 if len == self.buf.cap() { 1056 self.reserve(1); 1057 } 1058 1059 unsafe { 1060 // infallible 1061 // The spot to put the new value 1062 { 1063 let p = self.as_mut_ptr().add(index); 1064 // Shift everything over to make space. (Duplicating the 1065 // `index`th element into two consecutive places.) 1066 ptr::copy(p, p.offset(1), len - index); 1067 // Write it in, overwriting the first copy of the `index`th 1068 // element. 1069 ptr::write(p, element); 1070 } 1071 self.set_len(len + 1); 1072 } 1073 } 1074 1075 /// Removes and returns the element at position `index` within the vector, 1076 /// shifting all elements after it to the left. 1077 /// 1078 /// # Panics 1079 /// 1080 /// Panics if `index` is out of bounds. 1081 /// 1082 /// # Examples 1083 /// 1084 /// ``` 1085 /// use bumpalo::{Bump, collections::Vec}; 1086 /// 1087 /// let b = Bump::new(); 1088 /// 1089 /// let mut v = bumpalo::vec![in &b; 1, 2, 3]; 1090 /// assert_eq!(v.remove(1), 2); 1091 /// assert_eq!(v, [1, 3]); 1092 /// ``` 1093 pub fn remove(&mut self, index: usize) -> T { 1094 let len = self.len(); 1095 assert!(index < len); 1096 unsafe { 1097 // infallible 1098 let ret; 1099 { 1100 // the place we are taking from. 1101 let ptr = self.as_mut_ptr().add(index); 1102 // copy it out, unsafely having a copy of the value on 1103 // the stack and in the vector at the same time. 1104 ret = ptr::read(ptr); 1105 1106 // Shift everything down to fill in that spot. 1107 ptr::copy(ptr.offset(1), ptr, len - index - 1); 1108 } 1109 self.set_len(len - 1); 1110 ret 1111 } 1112 } 1113 1114 /// Retains only the elements specified by the predicate. 1115 /// 1116 /// In other words, remove all elements `e` such that `f(&e)` returns `false`. 1117 /// This method operates in place and preserves the order of the retained 1118 /// elements. 1119 /// 1120 /// # Examples 1121 /// 1122 /// ``` 1123 /// use bumpalo::{Bump, collections::Vec}; 1124 /// 1125 /// let b = Bump::new(); 1126 /// 1127 /// let mut vec = bumpalo::vec![in &b; 1, 2, 3, 4]; 1128 /// vec.retain(|&x| x%2 == 0); 1129 /// assert_eq!(vec, [2, 4]); 1130 /// ``` 1131 pub fn retain<F>(&mut self, mut f: F) 1132 where 1133 F: FnMut(&T) -> bool, 1134 { 1135 self.drain_filter(|x| !f(x)); 1136 } 1137 1138 fn drain_filter<'a, F>(&'a mut self, filter: F) -> DrainFilter<'a, 'bump, T, F> 1139 where 1140 F: FnMut(&mut T) -> bool, 1141 { 1142 let old_len = self.len(); 1143 1144 // Guard against us getting leaked (leak amplification) 1145 unsafe { 1146 self.set_len(0); 1147 } 1148 1149 DrainFilter { 1150 vec: self, 1151 idx: 0, 1152 del: 0, 1153 old_len, 1154 pred: filter, 1155 } 1156 } 1157 1158 /// Removes all but the first of consecutive elements in the vector that resolve to the same 1159 /// key. 1160 /// 1161 /// If the vector is sorted, this removes all duplicates. 1162 /// 1163 /// # Examples 1164 /// 1165 /// ``` 1166 /// use bumpalo::{Bump, collections::Vec}; 1167 /// 1168 /// let b = Bump::new(); 1169 /// 1170 /// let mut vec = bumpalo::vec![in &b; 10, 20, 21, 30, 20]; 1171 /// 1172 /// vec.dedup_by_key(|i| *i / 10); 1173 /// 1174 /// assert_eq!(vec, [10, 20, 30, 20]); 1175 /// ``` 1176 #[inline] 1177 pub fn dedup_by_key<F, K>(&mut self, mut key: F) 1178 where 1179 F: FnMut(&mut T) -> K, 1180 K: PartialEq, 1181 { 1182 self.dedup_by(|a, b| key(a) == key(b)) 1183 } 1184 1185 /// Removes all but the first of consecutive elements in the vector satisfying a given equality 1186 /// relation. 1187 /// 1188 /// The `same_bucket` function is passed references to two elements from the vector and 1189 /// must determine if the elements compare equal. The elements are passed in opposite order 1190 /// from their order in the slice, so if `same_bucket(a, b)` returns `true`, `a` is removed. 1191 /// 1192 /// If the vector is sorted, this removes all duplicates. 1193 /// 1194 /// # Examples 1195 /// 1196 /// ``` 1197 /// use bumpalo::{Bump, collections::Vec}; 1198 /// 1199 /// let b = Bump::new(); 1200 /// 1201 /// let mut vec = bumpalo::vec![in &b; "foo", "bar", "Bar", "baz", "bar"]; 1202 /// 1203 /// vec.dedup_by(|a, b| a.eq_ignore_ascii_case(b)); 1204 /// 1205 /// assert_eq!(vec, ["foo", "bar", "baz", "bar"]); 1206 /// ``` 1207 pub fn dedup_by<F>(&mut self, same_bucket: F) 1208 where 1209 F: FnMut(&mut T, &mut T) -> bool, 1210 { 1211 let len = { 1212 let (dedup, _) = partition_dedup_by(self.as_mut_slice(), same_bucket); 1213 dedup.len() 1214 }; 1215 self.truncate(len); 1216 } 1217 1218 /// Appends an element to the back of a collection. 1219 /// 1220 /// # Panics 1221 /// 1222 /// Panics if the number of elements in the vector overflows a `usize`. 1223 /// 1224 /// # Examples 1225 /// 1226 /// ``` 1227 /// use bumpalo::{Bump, collections::Vec}; 1228 /// 1229 /// let b = Bump::new(); 1230 /// 1231 /// let mut vec = bumpalo::vec![in &b; 1, 2]; 1232 /// vec.push(3); 1233 /// assert_eq!(vec, [1, 2, 3]); 1234 /// ``` 1235 #[inline] 1236 pub fn push(&mut self, value: T) { 1237 // This will panic or abort if we would allocate > isize::MAX bytes 1238 // or if the length increment would overflow for zero-sized types. 1239 if self.len == self.buf.cap() { 1240 self.reserve(1); 1241 } 1242 unsafe { 1243 let end = self.as_mut_ptr().add(self.len); 1244 ptr::write(end, value); 1245 self.len += 1; 1246 } 1247 } 1248 1249 /// Removes the last element from a vector and returns it, or [`None`] if it 1250 /// is empty. 1251 /// 1252 /// [`None`]: https://doc.rust-lang.org/nightly/std/option/enum.Option.html#variant.None 1253 /// 1254 /// # Examples 1255 /// 1256 /// ``` 1257 /// use bumpalo::{Bump, collections::Vec}; 1258 /// 1259 /// let b = Bump::new(); 1260 /// 1261 /// let mut vec = bumpalo::vec![in &b; 1, 2, 3]; 1262 /// assert_eq!(vec.pop(), Some(3)); 1263 /// assert_eq!(vec, [1, 2]); 1264 /// ``` 1265 #[inline] 1266 pub fn pop(&mut self) -> Option<T> { 1267 if self.len == 0 { 1268 None 1269 } else { 1270 unsafe { 1271 self.len -= 1; 1272 Some(ptr::read(self.get_unchecked(self.len()))) 1273 } 1274 } 1275 } 1276 1277 /// Moves all the elements of `other` into `Self`, leaving `other` empty. 1278 /// 1279 /// # Panics 1280 /// 1281 /// Panics if the number of elements in the vector overflows a `usize`. 1282 /// 1283 /// # Examples 1284 /// 1285 /// ``` 1286 /// use bumpalo::{Bump, collections::Vec}; 1287 /// 1288 /// let b = Bump::new(); 1289 /// 1290 /// let mut vec = bumpalo::vec![in &b; 1, 2, 3]; 1291 /// let mut vec2 = bumpalo::vec![in &b; 4, 5, 6]; 1292 /// vec.append(&mut vec2); 1293 /// assert_eq!(vec, [1, 2, 3, 4, 5, 6]); 1294 /// assert_eq!(vec2, []); 1295 /// ``` 1296 #[inline] 1297 pub fn append(&mut self, other: &mut Self) { 1298 unsafe { 1299 self.append_elements(other.as_slice() as _); 1300 other.set_len(0); 1301 } 1302 } 1303 1304 /// Appends elements to `Self` from other buffer. 1305 #[inline] 1306 unsafe fn append_elements(&mut self, other: *const [T]) { 1307 let count = (*other).len(); 1308 self.reserve(count); 1309 let len = self.len(); 1310 ptr::copy_nonoverlapping(other as *const T, self.get_unchecked_mut(len), count); 1311 self.len += count; 1312 } 1313 1314 /// Creates a draining iterator that removes the specified range in the vector 1315 /// and yields the removed items. 1316 /// 1317 /// Note 1: The element range is removed even if the iterator is only 1318 /// partially consumed or not consumed at all. 1319 /// 1320 /// Note 2: It is unspecified how many elements are removed from the vector 1321 /// if the `Drain` value is leaked. 1322 /// 1323 /// # Panics 1324 /// 1325 /// Panics if the starting point is greater than the end point or if 1326 /// the end point is greater than the length of the vector. 1327 /// 1328 /// # Examples 1329 /// 1330 /// ``` 1331 /// use bumpalo::{Bump, collections::Vec}; 1332 /// 1333 /// let b = Bump::new(); 1334 /// 1335 /// let mut v = bumpalo::vec![in &b; 1, 2, 3]; 1336 /// 1337 /// let mut u: Vec<_> = Vec::new_in(&b); 1338 /// u.extend(v.drain(1..)); 1339 /// 1340 /// assert_eq!(v, &[1]); 1341 /// assert_eq!(u, &[2, 3]); 1342 /// 1343 /// // A full range clears the vector 1344 /// v.drain(..); 1345 /// assert_eq!(v, &[]); 1346 /// ``` 1347 pub fn drain<R>(&mut self, range: R) -> Drain<T> 1348 where 1349 R: RangeBounds<usize>, 1350 { 1351 // Memory safety 1352 // 1353 // When the Drain is first created, it shortens the length of 1354 // the source vector to make sure no uninitialized or moved-from elements 1355 // are accessible at all if the Drain's destructor never gets to run. 1356 // 1357 // Drain will ptr::read out the values to remove. 1358 // When finished, remaining tail of the vec is copied back to cover 1359 // the hole, and the vector length is restored to the new length. 1360 // 1361 let len = self.len(); 1362 let start = match range.start_bound() { 1363 Included(&n) => n, 1364 Excluded(&n) => n + 1, 1365 Unbounded => 0, 1366 }; 1367 let end = match range.end_bound() { 1368 Included(&n) => n + 1, 1369 Excluded(&n) => n, 1370 Unbounded => len, 1371 }; 1372 assert!(start <= end); 1373 assert!(end <= len); 1374 1375 unsafe { 1376 // set self.vec length's to start, to be safe in case Drain is leaked 1377 self.set_len(start); 1378 // Use the borrow in the IterMut to indicate borrowing behavior of the 1379 // whole Drain iterator (like &mut T). 1380 let range_slice = slice::from_raw_parts_mut(self.as_mut_ptr().add(start), end - start); 1381 Drain { 1382 tail_start: end, 1383 tail_len: len - end, 1384 iter: range_slice.iter(), 1385 vec: NonNull::from(self), 1386 } 1387 } 1388 } 1389 1390 /// Clears the vector, removing all values. 1391 /// 1392 /// Note that this method has no effect on the allocated capacity 1393 /// of the vector. 1394 /// 1395 /// # Examples 1396 /// 1397 /// ``` 1398 /// use bumpalo::{Bump, collections::Vec}; 1399 /// 1400 /// let b = Bump::new(); 1401 /// 1402 /// let mut v = bumpalo::vec![in &b; 1, 2, 3]; 1403 /// 1404 /// v.clear(); 1405 /// 1406 /// assert!(v.is_empty()); 1407 /// ``` 1408 #[inline] 1409 pub fn clear(&mut self) { 1410 self.truncate(0) 1411 } 1412 1413 /// Returns the number of elements in the vector, also referred to 1414 /// as its 'length'. 1415 /// 1416 /// # Examples 1417 /// 1418 /// ``` 1419 /// use bumpalo::{Bump, collections::Vec}; 1420 /// 1421 /// let b = Bump::new(); 1422 /// 1423 /// let a = bumpalo::vec![in &b; 1, 2, 3]; 1424 /// assert_eq!(a.len(), 3); 1425 /// ``` 1426 #[inline] 1427 pub fn len(&self) -> usize { 1428 self.len 1429 } 1430 1431 /// Returns `true` if the vector contains no elements. 1432 /// 1433 /// # Examples 1434 /// 1435 /// ``` 1436 /// use bumpalo::{Bump, collections::Vec}; 1437 /// 1438 /// let b = Bump::new(); 1439 /// 1440 /// let mut v = Vec::new_in(&b); 1441 /// assert!(v.is_empty()); 1442 /// 1443 /// v.push(1); 1444 /// assert!(!v.is_empty()); 1445 /// ``` 1446 pub fn is_empty(&self) -> bool { 1447 self.len() == 0 1448 } 1449 1450 /// Splits the collection into two at the given index. 1451 /// 1452 /// Returns a newly allocated `Self`. `self` contains elements `[0, at)`, 1453 /// and the returned `Self` contains elements `[at, len)`. 1454 /// 1455 /// Note that the capacity of `self` does not change. 1456 /// 1457 /// # Panics 1458 /// 1459 /// Panics if `at > len`. 1460 /// 1461 /// # Examples 1462 /// 1463 /// ``` 1464 /// use bumpalo::{Bump, collections::Vec}; 1465 /// 1466 /// let b = Bump::new(); 1467 /// 1468 /// let mut vec = bumpalo::vec![in &b; 1,2,3]; 1469 /// let vec2 = vec.split_off(1); 1470 /// assert_eq!(vec, [1]); 1471 /// assert_eq!(vec2, [2, 3]); 1472 /// ``` 1473 #[inline] 1474 pub fn split_off(&mut self, at: usize) -> Self { 1475 assert!(at <= self.len(), "`at` out of bounds"); 1476 1477 let other_len = self.len - at; 1478 let mut other = Vec::with_capacity_in(other_len, self.buf.bump()); 1479 1480 // Unsafely `set_len` and copy items to `other`. 1481 unsafe { 1482 self.set_len(at); 1483 other.set_len(other_len); 1484 1485 ptr::copy_nonoverlapping(self.as_ptr().add(at), other.as_mut_ptr(), other.len()); 1486 } 1487 other 1488 } 1489 } 1490 1491 impl<'bump, T: 'bump + Clone> Vec<'bump, T> { 1492 /// Resizes the `Vec` in-place so that `len` is equal to `new_len`. 1493 /// 1494 /// If `new_len` is greater than `len`, the `Vec` is extended by the 1495 /// difference, with each additional slot filled with `value`. 1496 /// If `new_len` is less than `len`, the `Vec` is simply truncated. 1497 /// 1498 /// This method requires [`Clone`] to be able clone the passed value. If 1499 /// you need more flexibility (or want to rely on [`Default`] instead of 1500 /// [`Clone`]), use [`resize_with`]. 1501 /// 1502 /// # Examples 1503 /// 1504 /// ``` 1505 /// use bumpalo::{Bump, collections::Vec}; 1506 /// 1507 /// let b = Bump::new(); 1508 /// 1509 /// let mut vec = bumpalo::vec![in &b; "hello"]; 1510 /// vec.resize(3, "world"); 1511 /// assert_eq!(vec, ["hello", "world", "world"]); 1512 /// 1513 /// let mut vec = bumpalo::vec![in &b; 1, 2, 3, 4]; 1514 /// vec.resize(2, 0); 1515 /// assert_eq!(vec, [1, 2]); 1516 /// ``` 1517 /// 1518 /// [`Clone`]: https://doc.rust-lang.org/nightly/std/clone/trait.Clone.html 1519 /// [`Default`]: https://doc.rust-lang.org/nightly/std/default/trait.Default.html 1520 /// [`resize_with`]: #method.resize_with 1521 pub fn resize(&mut self, new_len: usize, value: T) { 1522 let len = self.len(); 1523 1524 if new_len > len { 1525 self.extend_with(new_len - len, ExtendElement(value)) 1526 } else { 1527 self.truncate(new_len); 1528 } 1529 } 1530 1531 /// Clones and appends all elements in a slice to the `Vec`. 1532 /// 1533 /// Iterates over the slice `other`, clones each element, and then appends 1534 /// it to this `Vec`. The `other` vector is traversed in-order. 1535 /// 1536 /// Note that this function is same as [`extend`] except that it is 1537 /// specialized to work with slices instead. If and when Rust gets 1538 /// specialization this function will likely be deprecated (but still 1539 /// available). 1540 /// 1541 /// # Examples 1542 /// 1543 /// ``` 1544 /// use bumpalo::{Bump, collections::Vec}; 1545 /// 1546 /// let b = Bump::new(); 1547 /// 1548 /// let mut vec = bumpalo::vec![in &b; 1]; 1549 /// vec.extend_from_slice(&[2, 3, 4]); 1550 /// assert_eq!(vec, [1, 2, 3, 4]); 1551 /// ``` 1552 /// 1553 /// [`extend`]: #method.extend 1554 pub fn extend_from_slice(&mut self, other: &[T]) { 1555 self.extend(other.iter().cloned()) 1556 } 1557 } 1558 1559 // This code generalises `extend_with_{element,default}`. 1560 trait ExtendWith<T> { 1561 fn next(&mut self) -> T; 1562 fn last(self) -> T; 1563 } 1564 1565 struct ExtendElement<T>(T); 1566 impl<T: Clone> ExtendWith<T> for ExtendElement<T> { 1567 fn next(&mut self) -> T { 1568 self.0.clone() 1569 } 1570 fn last(self) -> T { 1571 self.0 1572 } 1573 } 1574 1575 impl<'bump, T: 'bump> Vec<'bump, T> { 1576 /// Extend the vector by `n` values, using the given generator. 1577 fn extend_with<E: ExtendWith<T>>(&mut self, n: usize, mut value: E) { 1578 self.reserve(n); 1579 1580 unsafe { 1581 let mut ptr = self.as_mut_ptr().add(self.len()); 1582 // Use SetLenOnDrop to work around bug where compiler 1583 // may not realize the store through `ptr` through self.set_len() 1584 // don't alias. 1585 let mut local_len = SetLenOnDrop::new(&mut self.len); 1586 1587 // Write all elements except the last one 1588 for _ in 1..n { 1589 ptr::write(ptr, value.next()); 1590 ptr = ptr.offset(1); 1591 // Increment the length in every step in case next() panics 1592 local_len.increment_len(1); 1593 } 1594 1595 if n > 0 { 1596 // We can write the last element directly without cloning needlessly 1597 ptr::write(ptr, value.last()); 1598 local_len.increment_len(1); 1599 } 1600 1601 // len set by scope guard 1602 } 1603 } 1604 } 1605 1606 // Set the length of the vec when the `SetLenOnDrop` value goes out of scope. 1607 // 1608 // The idea is: The length field in SetLenOnDrop is a local variable 1609 // that the optimizer will see does not alias with any stores through the Vec's data 1610 // pointer. This is a workaround for alias analysis issue #32155 1611 struct SetLenOnDrop<'a> { 1612 len: &'a mut usize, 1613 local_len: usize, 1614 } 1615 1616 impl<'a> SetLenOnDrop<'a> { 1617 #[inline] 1618 fn new(len: &'a mut usize) -> Self { 1619 SetLenOnDrop { 1620 local_len: *len, 1621 len, 1622 } 1623 } 1624 1625 #[inline] 1626 fn increment_len(&mut self, increment: usize) { 1627 self.local_len += increment; 1628 } 1629 1630 #[inline] 1631 fn decrement_len(&mut self, decrement: usize) { 1632 self.local_len -= decrement; 1633 } 1634 } 1635 1636 impl<'a> Drop for SetLenOnDrop<'a> { 1637 #[inline] 1638 fn drop(&mut self) { 1639 *self.len = self.local_len; 1640 } 1641 } 1642 1643 impl<'bump, T: 'bump + PartialEq> Vec<'bump, T> { 1644 /// Removes consecutive repeated elements in the vector according to the 1645 /// [`PartialEq`] trait implementation. 1646 /// 1647 /// If the vector is sorted, this removes all duplicates. 1648 /// 1649 /// # Examples 1650 /// 1651 /// ``` 1652 /// use bumpalo::{Bump, collections::Vec}; 1653 /// 1654 /// let b = Bump::new(); 1655 /// 1656 /// let mut vec = bumpalo::vec![in &b; 1, 2, 2, 3, 2]; 1657 /// 1658 /// vec.dedup(); 1659 /// 1660 /// assert_eq!(vec, [1, 2, 3, 2]); 1661 /// ``` 1662 #[inline] 1663 pub fn dedup(&mut self) { 1664 self.dedup_by(|a, b| a == b) 1665 } 1666 } 1667 1668 //////////////////////////////////////////////////////////////////////////////// 1669 // Common trait implementations for Vec 1670 //////////////////////////////////////////////////////////////////////////////// 1671 1672 impl<'bump, T: 'bump + Clone> Clone for Vec<'bump, T> { 1673 #[cfg(not(test))] 1674 fn clone(&self) -> Vec<'bump, T> { 1675 let mut v = Vec::with_capacity_in(self.len(), self.buf.bump()); 1676 v.extend(self.iter().cloned()); 1677 v 1678 } 1679 1680 // HACK(japaric): with cfg(test) the inherent `[T]::to_vec` method, which is 1681 // required for this method definition, is not available. Instead use the 1682 // `slice::to_vec` function which is only available with cfg(test) 1683 // NB see the slice::hack module in slice.rs for more information 1684 #[cfg(test)] 1685 fn clone(&self) -> Vec<'bump, T> { 1686 let mut v = Vec::new_in(self.buf.bump()); 1687 v.extend(self.iter().cloned()); 1688 v 1689 } 1690 } 1691 1692 impl<'bump, T: 'bump + Hash> Hash for Vec<'bump, T> { 1693 #[inline] 1694 fn hash<H: hash::Hasher>(&self, state: &mut H) { 1695 Hash::hash(&**self, state) 1696 } 1697 } 1698 1699 impl<'bump, T, I> Index<I> for Vec<'bump, T> 1700 where 1701 I: ::core::slice::SliceIndex<[T]>, 1702 { 1703 type Output = I::Output; 1704 1705 #[inline] 1706 fn index(&self, index: I) -> &Self::Output { 1707 Index::index(&**self, index) 1708 } 1709 } 1710 1711 impl<'bump, T, I> IndexMut<I> for Vec<'bump, T> 1712 where 1713 I: ::core::slice::SliceIndex<[T]>, 1714 { 1715 #[inline] 1716 fn index_mut(&mut self, index: I) -> &mut Self::Output { 1717 IndexMut::index_mut(&mut **self, index) 1718 } 1719 } 1720 1721 impl<'bump, T: 'bump> ops::Deref for Vec<'bump, T> { 1722 type Target = [T]; 1723 1724 fn deref(&self) -> &[T] { 1725 unsafe { 1726 let p = self.buf.ptr(); 1727 // assume(!p.is_null()); 1728 slice::from_raw_parts(p, self.len) 1729 } 1730 } 1731 } 1732 1733 impl<'bump, T: 'bump> ops::DerefMut for Vec<'bump, T> { 1734 fn deref_mut(&mut self) -> &mut [T] { 1735 unsafe { 1736 let ptr = self.buf.ptr(); 1737 // assume(!ptr.is_null()); 1738 slice::from_raw_parts_mut(ptr, self.len) 1739 } 1740 } 1741 } 1742 1743 impl<'bump, T: 'bump> IntoIterator for Vec<'bump, T> { 1744 type Item = T; 1745 type IntoIter = IntoIter<T>; 1746 1747 /// Creates a consuming iterator, that is, one that moves each value out of 1748 /// the vector (from start to end). The vector cannot be used after calling 1749 /// this. 1750 /// 1751 /// # Examples 1752 /// 1753 /// ``` 1754 /// use bumpalo::{Bump, collections::Vec}; 1755 /// 1756 /// let b = Bump::new(); 1757 /// 1758 /// let v = bumpalo::vec![in &b; "a".to_string(), "b".to_string()]; 1759 /// for s in v.into_iter() { 1760 /// // s has type String, not &String 1761 /// println!("{}", s); 1762 /// } 1763 /// ``` 1764 #[inline] 1765 fn into_iter(mut self) -> IntoIter<T> { 1766 unsafe { 1767 let begin = self.as_mut_ptr(); 1768 // assume(!begin.is_null()); 1769 let end = if mem::size_of::<T>() == 0 { 1770 arith_offset(begin as *const i8, self.len() as isize) as *const T 1771 } else { 1772 begin.add(self.len()) as *const T 1773 }; 1774 mem::forget(self); 1775 IntoIter { 1776 phantom: PhantomData, 1777 ptr: begin, 1778 end, 1779 } 1780 } 1781 } 1782 } 1783 1784 impl<'a, 'bump, T> IntoIterator for &'a Vec<'bump, T> { 1785 type Item = &'a T; 1786 type IntoIter = slice::Iter<'a, T>; 1787 1788 fn into_iter(self) -> slice::Iter<'a, T> { 1789 self.iter() 1790 } 1791 } 1792 1793 impl<'a, 'bump, T> IntoIterator for &'a mut Vec<'bump, T> { 1794 type Item = &'a mut T; 1795 type IntoIter = slice::IterMut<'a, T>; 1796 1797 fn into_iter(self) -> slice::IterMut<'a, T> { 1798 self.iter_mut() 1799 } 1800 } 1801 1802 impl<'bump, T: 'bump> Extend<T> for Vec<'bump, T> { 1803 #[inline] 1804 fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) { 1805 let iter = iter.into_iter(); 1806 self.reserve(iter.size_hint().0); 1807 1808 for t in iter { 1809 self.push(t); 1810 } 1811 } 1812 } 1813 1814 impl<'bump, T: 'bump> Vec<'bump, T> { 1815 /// Creates a splicing iterator that replaces the specified range in the vector 1816 /// with the given `replace_with` iterator and yields the removed items. 1817 /// `replace_with` does not need to be the same length as `range`. 1818 /// 1819 /// Note 1: The element range is removed even if the iterator is not 1820 /// consumed until the end. 1821 /// 1822 /// Note 2: It is unspecified how many elements are removed from the vector, 1823 /// if the `Splice` value is leaked. 1824 /// 1825 /// Note 3: The input iterator `replace_with` is only consumed 1826 /// when the `Splice` value is dropped. 1827 /// 1828 /// Note 4: This is optimal if: 1829 /// 1830 /// * The tail (elements in the vector after `range`) is empty, 1831 /// * or `replace_with` yields fewer elements than `range`’s length 1832 /// * or the lower bound of its `size_hint()` is exact. 1833 /// 1834 /// Otherwise, a temporary vector is allocated and the tail is moved twice. 1835 /// 1836 /// # Panics 1837 /// 1838 /// Panics if the starting point is greater than the end point or if 1839 /// the end point is greater than the length of the vector. 1840 /// 1841 /// # Examples 1842 /// 1843 /// ``` 1844 /// use bumpalo::{Bump, collections::Vec}; 1845 /// 1846 /// let b = Bump::new(); 1847 /// 1848 /// let mut v = bumpalo::vec![in &b; 1, 2, 3]; 1849 /// let new = [7, 8]; 1850 /// let u: Vec<_> = Vec::from_iter_in(v.splice(..2, new.iter().cloned()), &b); 1851 /// assert_eq!(v, &[7, 8, 3]); 1852 /// assert_eq!(u, &[1, 2]); 1853 /// ``` 1854 #[inline] 1855 pub fn splice<R, I>(&mut self, range: R, replace_with: I) -> Splice<I::IntoIter> 1856 where 1857 R: RangeBounds<usize>, 1858 I: IntoIterator<Item = T>, 1859 { 1860 Splice { 1861 drain: self.drain(range), 1862 replace_with: replace_with.into_iter(), 1863 } 1864 } 1865 } 1866 1867 /// Extend implementation that copies elements out of references before pushing them onto the Vec. 1868 /// 1869 /// This implementation is specialized for slice iterators, where it uses [`copy_from_slice`] to 1870 /// append the entire slice at once. 1871 /// 1872 /// [`copy_from_slice`]: https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.copy_from_slice 1873 impl<'a, 'bump, T: 'a + Copy> Extend<&'a T> for Vec<'bump, T> { 1874 fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) { 1875 self.extend(iter.into_iter().cloned()) 1876 } 1877 } 1878 1879 macro_rules! __impl_slice_eq1 { 1880 ($Lhs: ty, $Rhs: ty) => { 1881 __impl_slice_eq1! { $Lhs, $Rhs, Sized } 1882 }; 1883 ($Lhs: ty, $Rhs: ty, $Bound: ident) => { 1884 impl<'a, 'b, A: $Bound, B> PartialEq<$Rhs> for $Lhs 1885 where 1886 A: PartialEq<B>, 1887 { 1888 #[inline] 1889 fn eq(&self, other: &$Rhs) -> bool { 1890 self[..] == other[..] 1891 } 1892 } 1893 }; 1894 } 1895 1896 __impl_slice_eq1! { Vec<'a, A>, Vec<'b, B> } 1897 __impl_slice_eq1! { Vec<'a, A>, &'b [B] } 1898 __impl_slice_eq1! { Vec<'a, A>, &'b mut [B] } 1899 // __impl_slice_eq1! { Cow<'a, [A]>, Vec<'b, B>, Clone } 1900 1901 macro_rules! array_impls { 1902 ($($N: expr)+) => { 1903 $( 1904 // NOTE: some less important impls are omitted to reduce code bloat 1905 __impl_slice_eq1! { Vec<'a, A>, [B; $N] } 1906 __impl_slice_eq1! { Vec<'a, A>, &'b [B; $N] } 1907 // __impl_slice_eq1! { Vec<A>, &'b mut [B; $N] } 1908 // __impl_slice_eq1! { Cow<'a, [A]>, [B; $N], Clone } 1909 // __impl_slice_eq1! { Cow<'a, [A]>, &'b [B; $N], Clone } 1910 // __impl_slice_eq1! { Cow<'a, [A]>, &'b mut [B; $N], Clone } 1911 )+ 1912 } 1913 } 1914 1915 array_impls! { 1916 0 1 2 3 4 5 6 7 8 9 1917 10 11 12 13 14 15 16 17 18 19 1918 20 21 22 23 24 25 26 27 28 29 1919 30 31 32 1920 } 1921 1922 /// Implements comparison of vectors, lexicographically. 1923 impl<'bump, T: 'bump + PartialOrd> PartialOrd for Vec<'bump, T> { 1924 #[inline] 1925 fn partial_cmp(&self, other: &Vec<'bump, T>) -> Option<Ordering> { 1926 PartialOrd::partial_cmp(&**self, &**other) 1927 } 1928 } 1929 1930 impl<'bump, T: 'bump + Eq> Eq for Vec<'bump, T> {} 1931 1932 /// Implements ordering of vectors, lexicographically. 1933 impl<'bump, T: 'bump + Ord> Ord for Vec<'bump, T> { 1934 #[inline] 1935 fn cmp(&self, other: &Vec<'bump, T>) -> Ordering { 1936 Ord::cmp(&**self, &**other) 1937 } 1938 } 1939 1940 impl<'bump, T: 'bump + fmt::Debug> fmt::Debug for Vec<'bump, T> { 1941 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { 1942 fmt::Debug::fmt(&**self, f) 1943 } 1944 } 1945 1946 impl<'bump, T: 'bump> AsRef<Vec<'bump, T>> for Vec<'bump, T> { 1947 fn as_ref(&self) -> &Vec<'bump, T> { 1948 self 1949 } 1950 } 1951 1952 impl<'bump, T: 'bump> AsMut<Vec<'bump, T>> for Vec<'bump, T> { 1953 fn as_mut(&mut self) -> &mut Vec<'bump, T> { 1954 self 1955 } 1956 } 1957 1958 impl<'bump, T: 'bump> AsRef<[T]> for Vec<'bump, T> { 1959 fn as_ref(&self) -> &[T] { 1960 self 1961 } 1962 } 1963 1964 impl<'bump, T: 'bump> AsMut<[T]> for Vec<'bump, T> { 1965 fn as_mut(&mut self) -> &mut [T] { 1966 self 1967 } 1968 } 1969 1970 // // note: test pulls in libstd, which causes errors here 1971 // #[cfg(not(test))] 1972 // impl<'bump, T: 'bump> From<Vec<'bump, T>> for Box<[T]> { 1973 // fn from(v: Vec<'bump, T>) -> Box<[T]> { 1974 // v.into_boxed_slice() 1975 // } 1976 // } 1977 1978 //////////////////////////////////////////////////////////////////////////////// 1979 // Clone-on-write 1980 //////////////////////////////////////////////////////////////////////////////// 1981 1982 // impl<'a, 'bump, T: Clone> From<Vec<'bump, T>> for Cow<'a, [T]> { 1983 // fn from(v: Vec<'bump, T>) -> Cow<'a, [T]> { 1984 // Cow::Owned(v) 1985 // } 1986 // } 1987 1988 // impl<'a, 'bump, T: Clone> From<&'a Vec<'bump, T>> for Cow<'a, [T]> { 1989 // fn from(v: &'a Vec<'bump, T>) -> Cow<'a, [T]> { 1990 // Cow::Borrowed(v.as_slice()) 1991 // } 1992 // } 1993 1994 //////////////////////////////////////////////////////////////////////////////// 1995 // Iterators 1996 //////////////////////////////////////////////////////////////////////////////// 1997 1998 /// An iterator that moves out of a vector. 1999 /// 2000 /// This `struct` is created by the `into_iter` method on [`Vec`][`Vec`] (provided 2001 /// by the [`IntoIterator`] trait). 2002 /// 2003 /// [`Vec`]: struct.Vec.html 2004 /// [`IntoIterator`]: https://doc.rust-lang.org/nightly/std/iter/trait.IntoIterator.html 2005 pub struct IntoIter<T> { 2006 phantom: PhantomData<T>, 2007 ptr: *const T, 2008 end: *const T, 2009 } 2010 2011 impl<T: fmt::Debug> fmt::Debug for IntoIter<T> { 2012 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { 2013 f.debug_tuple("IntoIter").field(&self.as_slice()).finish() 2014 } 2015 } 2016 2017 impl<'bump, T: 'bump> IntoIter<T> { 2018 /// Returns the remaining items of this iterator as a slice. 2019 /// 2020 /// # Examples 2021 /// 2022 /// ``` 2023 /// use bumpalo::{Bump, collections::Vec}; 2024 /// 2025 /// let b = Bump::new(); 2026 /// 2027 /// let vec = bumpalo::vec![in &b; 'a', 'b', 'c']; 2028 /// let mut into_iter = vec.into_iter(); 2029 /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']); 2030 /// let _ = into_iter.next().unwrap(); 2031 /// assert_eq!(into_iter.as_slice(), &['b', 'c']); 2032 /// ``` 2033 pub fn as_slice(&self) -> &[T] { 2034 unsafe { slice::from_raw_parts(self.ptr, self.len()) } 2035 } 2036 2037 /// Returns the remaining items of this iterator as a mutable slice. 2038 /// 2039 /// # Examples 2040 /// 2041 /// ``` 2042 /// use bumpalo::{Bump, collections::Vec}; 2043 /// 2044 /// let b = Bump::new(); 2045 /// 2046 /// let vec = bumpalo::vec![in &b; 'a', 'b', 'c']; 2047 /// let mut into_iter = vec.into_iter(); 2048 /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']); 2049 /// into_iter.as_mut_slice()[2] = 'z'; 2050 /// assert_eq!(into_iter.next().unwrap(), 'a'); 2051 /// assert_eq!(into_iter.next().unwrap(), 'b'); 2052 /// assert_eq!(into_iter.next().unwrap(), 'z'); 2053 /// ``` 2054 pub fn as_mut_slice(&mut self) -> &mut [T] { 2055 unsafe { slice::from_raw_parts_mut(self.ptr as *mut T, self.len()) } 2056 } 2057 } 2058 2059 unsafe impl<T: Send> Send for IntoIter<T> {} 2060 unsafe impl<T: Sync> Sync for IntoIter<T> {} 2061 2062 impl<'bump, T: 'bump> Iterator for IntoIter<T> { 2063 type Item = T; 2064 2065 #[inline] 2066 fn next(&mut self) -> Option<T> { 2067 unsafe { 2068 if self.ptr as *const _ == self.end { 2069 None 2070 } else if mem::size_of::<T>() == 0 { 2071 // purposefully don't use 'ptr.offset' because for 2072 // vectors with 0-size elements this would return the 2073 // same pointer. 2074 self.ptr = arith_offset(self.ptr as *const i8, 1) as *mut T; 2075 2076 // Make up a value of this ZST. 2077 Some(mem::zeroed()) 2078 } else { 2079 let old = self.ptr; 2080 self.ptr = self.ptr.offset(1); 2081 2082 Some(ptr::read(old)) 2083 } 2084 } 2085 } 2086 2087 #[inline] 2088 fn size_hint(&self) -> (usize, Option<usize>) { 2089 let exact = if mem::size_of::<T>() == 0 { 2090 (self.end as usize).wrapping_sub(self.ptr as usize) 2091 } else { 2092 unsafe { offset_from(self.end, self.ptr) as usize } 2093 }; 2094 (exact, Some(exact)) 2095 } 2096 2097 #[inline] 2098 fn count(self) -> usize { 2099 self.len() 2100 } 2101 } 2102 2103 impl<'bump, T: 'bump> DoubleEndedIterator for IntoIter<T> { 2104 #[inline] 2105 fn next_back(&mut self) -> Option<T> { 2106 unsafe { 2107 if self.end == self.ptr { 2108 None 2109 } else if mem::size_of::<T>() == 0 { 2110 // See above for why 'ptr.offset' isn't used 2111 self.end = arith_offset(self.end as *const i8, -1) as *mut T; 2112 2113 // Make up a value of this ZST. 2114 Some(mem::zeroed()) 2115 } else { 2116 self.end = self.end.offset(-1); 2117 2118 Some(ptr::read(self.end)) 2119 } 2120 } 2121 } 2122 } 2123 2124 impl<'bump, T: 'bump> ExactSizeIterator for IntoIter<T> {} 2125 2126 impl<'bump, T: 'bump> FusedIterator for IntoIter<T> {} 2127 2128 /// A draining iterator for `Vec<'bump, T>`. 2129 /// 2130 /// This `struct` is created by the [`drain`] method on [`Vec`]. 2131 /// 2132 /// [`drain`]: struct.Vec.html#method.drain 2133 /// [`Vec`]: struct.Vec.html 2134 pub struct Drain<'a, 'bump, T: 'a + 'bump> { 2135 /// Index of tail to preserve 2136 tail_start: usize, 2137 /// Length of tail 2138 tail_len: usize, 2139 /// Current remaining range to remove 2140 iter: slice::Iter<'a, T>, 2141 vec: NonNull<Vec<'bump, T>>, 2142 } 2143 2144 impl<'a, 'bump, T: 'a + 'bump + fmt::Debug> fmt::Debug for Drain<'a, 'bump, T> { 2145 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { 2146 f.debug_tuple("Drain").field(&self.iter.as_slice()).finish() 2147 } 2148 } 2149 2150 unsafe impl<'a, 'bump, T: Sync> Sync for Drain<'a, 'bump, T> {} 2151 unsafe impl<'a, 'bump, T: Send> Send for Drain<'a, 'bump, T> {} 2152 2153 impl<'a, 'bump, T> Iterator for Drain<'a, 'bump, T> { 2154 type Item = T; 2155 2156 #[inline] 2157 fn next(&mut self) -> Option<T> { 2158 self.iter 2159 .next() 2160 .map(|elt| unsafe { ptr::read(elt as *const _) }) 2161 } 2162 2163 fn size_hint(&self) -> (usize, Option<usize>) { 2164 self.iter.size_hint() 2165 } 2166 } 2167 2168 impl<'a, 'bump, T> DoubleEndedIterator for Drain<'a, 'bump, T> { 2169 #[inline] 2170 fn next_back(&mut self) -> Option<T> { 2171 self.iter 2172 .next_back() 2173 .map(|elt| unsafe { ptr::read(elt as *const _) }) 2174 } 2175 } 2176 2177 impl<'a, 'bump, T> Drop for Drain<'a, 'bump, T> { 2178 fn drop(&mut self) { 2179 // exhaust self first 2180 self.for_each(drop); 2181 2182 if self.tail_len > 0 { 2183 unsafe { 2184 let source_vec = self.vec.as_mut(); 2185 // memmove back untouched tail, update to new length 2186 let start = source_vec.len(); 2187 let tail = self.tail_start; 2188 if tail != start { 2189 let src = source_vec.as_ptr().add(tail); 2190 let dst = source_vec.as_mut_ptr().add(start); 2191 ptr::copy(src, dst, self.tail_len); 2192 } 2193 source_vec.set_len(start + self.tail_len); 2194 } 2195 } 2196 } 2197 } 2198 2199 impl<'a, 'bump, T> ExactSizeIterator for Drain<'a, 'bump, T> {} 2200 2201 impl<'a, 'bump, T> FusedIterator for Drain<'a, 'bump, T> {} 2202 2203 /// A splicing iterator for `Vec`. 2204 /// 2205 /// This struct is created by the [`splice()`] method on [`Vec`]. See its 2206 /// documentation for more. 2207 /// 2208 /// [`splice()`]: struct.Vec.html#method.splice 2209 /// [`Vec`]: struct.Vec.html 2210 #[derive(Debug)] 2211 pub struct Splice<'a, 'bump, I: Iterator + 'a + 'bump> { 2212 drain: Drain<'a, 'bump, I::Item>, 2213 replace_with: I, 2214 } 2215 2216 impl<'a, 'bump, I: Iterator> Iterator for Splice<'a, 'bump, I> { 2217 type Item = I::Item; 2218 2219 fn next(&mut self) -> Option<Self::Item> { 2220 self.drain.next() 2221 } 2222 2223 fn size_hint(&self) -> (usize, Option<usize>) { 2224 self.drain.size_hint() 2225 } 2226 } 2227 2228 impl<'a, 'bump, I: Iterator> DoubleEndedIterator for Splice<'a, 'bump, I> { 2229 fn next_back(&mut self) -> Option<Self::Item> { 2230 self.drain.next_back() 2231 } 2232 } 2233 2234 impl<'a, 'bump, I: Iterator> ExactSizeIterator for Splice<'a, 'bump, I> {} 2235 2236 impl<'a, 'bump, I: Iterator> Drop for Splice<'a, 'bump, I> { 2237 fn drop(&mut self) { 2238 self.drain.by_ref().for_each(drop); 2239 2240 unsafe { 2241 if self.drain.tail_len == 0 { 2242 self.drain.vec.as_mut().extend(self.replace_with.by_ref()); 2243 return; 2244 } 2245 2246 // First fill the range left by drain(). 2247 if !self.drain.fill(&mut self.replace_with) { 2248 return; 2249 } 2250 2251 // There may be more elements. Use the lower bound as an estimate. 2252 // FIXME: Is the upper bound a better guess? Or something else? 2253 let (lower_bound, _upper_bound) = self.replace_with.size_hint(); 2254 if lower_bound > 0 { 2255 self.drain.move_tail(lower_bound); 2256 if !self.drain.fill(&mut self.replace_with) { 2257 return; 2258 } 2259 } 2260 2261 // Collect any remaining elements. 2262 // This is a zero-length vector which does not allocate if `lower_bound` was exact. 2263 let mut collected = Vec::new_in(self.drain.vec.as_ref().buf.bump()); 2264 collected.extend(self.replace_with.by_ref()); 2265 let mut collected = collected.into_iter(); 2266 // Now we have an exact count. 2267 if collected.len() > 0 { 2268 self.drain.move_tail(collected.len()); 2269 let filled = self.drain.fill(&mut collected); 2270 debug_assert!(filled); 2271 debug_assert_eq!(collected.len(), 0); 2272 } 2273 } 2274 // Let `Drain::drop` move the tail back if necessary and restore `vec.len`. 2275 } 2276 } 2277 2278 /// Private helper methods for `Splice::drop` 2279 impl<'a, 'bump, T> Drain<'a, 'bump, T> { 2280 /// The range from `self.vec.len` to `self.tail_start` contains elements 2281 /// that have been moved out. 2282 /// Fill that range as much as possible with new elements from the `replace_with` iterator. 2283 /// Return whether we filled the entire range. (`replace_with.next()` didn’t return `None`.) 2284 unsafe fn fill<I: Iterator<Item = T>>(&mut self, replace_with: &mut I) -> bool { 2285 let vec = self.vec.as_mut(); 2286 let range_start = vec.len; 2287 let range_end = self.tail_start; 2288 let range_slice = 2289 slice::from_raw_parts_mut(vec.as_mut_ptr().add(range_start), range_end - range_start); 2290 2291 for place in range_slice { 2292 if let Some(new_item) = replace_with.next() { 2293 ptr::write(place, new_item); 2294 vec.len += 1; 2295 } else { 2296 return false; 2297 } 2298 } 2299 true 2300 } 2301 2302 /// Make room for inserting more elements before the tail. 2303 unsafe fn move_tail(&mut self, extra_capacity: usize) { 2304 let vec = self.vec.as_mut(); 2305 let used_capacity = self.tail_start + self.tail_len; 2306 vec.buf.reserve(used_capacity, extra_capacity); 2307 2308 let new_tail_start = self.tail_start + extra_capacity; 2309 let src = vec.as_ptr().add(self.tail_start); 2310 let dst = vec.as_mut_ptr().add(new_tail_start); 2311 ptr::copy(src, dst, self.tail_len); 2312 self.tail_start = new_tail_start; 2313 } 2314 } 2315 2316 /// An iterator produced by calling `drain_filter` on Vec. 2317 #[derive(Debug)] 2318 pub struct DrainFilter<'a, 'bump: 'a, T: 'a + 'bump, F> 2319 where 2320 F: FnMut(&mut T) -> bool, 2321 { 2322 vec: &'a mut Vec<'bump, T>, 2323 idx: usize, 2324 del: usize, 2325 old_len: usize, 2326 pred: F, 2327 } 2328 2329 impl<'a, 'bump, T, F> Iterator for DrainFilter<'a, 'bump, T, F> 2330 where 2331 F: FnMut(&mut T) -> bool, 2332 { 2333 type Item = T; 2334 2335 fn next(&mut self) -> Option<T> { 2336 unsafe { 2337 while self.idx != self.old_len { 2338 let i = self.idx; 2339 self.idx += 1; 2340 let v = slice::from_raw_parts_mut(self.vec.as_mut_ptr(), self.old_len); 2341 if (self.pred)(&mut v[i]) { 2342 self.del += 1; 2343 return Some(ptr::read(&v[i])); 2344 } else if self.del > 0 { 2345 let del = self.del; 2346 let src: *const T = &v[i]; 2347 let dst: *mut T = &mut v[i - del]; 2348 // This is safe because self.vec has length 0 2349 // thus its elements will not have Drop::drop 2350 // called on them in the event of a panic. 2351 ptr::copy_nonoverlapping(src, dst, 1); 2352 } 2353 } 2354 None 2355 } 2356 } 2357 2358 fn size_hint(&self) -> (usize, Option<usize>) { 2359 (0, Some(self.old_len - self.idx)) 2360 } 2361 } 2362 2363 impl<'a, 'bump, T, F> Drop for DrainFilter<'a, 'bump, T, F> 2364 where 2365 F: FnMut(&mut T) -> bool, 2366 { 2367 fn drop(&mut self) { 2368 self.for_each(drop); 2369 unsafe { 2370 self.vec.set_len(self.old_len - self.del); 2371 } 2372 } 2373 } 2374