refactor: moving Splice into splice.rs
This commit is contained in:
C
parent
434e5d1422
commit
17593f258b
@ -79,6 +79,11 @@ pub use self::drain_filter::DrainFilter;
|
||||
|
||||
mod drain_filter;
|
||||
|
||||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||||
pub use self::splice::Splice;
|
||||
|
||||
mod splice;
|
||||
|
||||
/// A contiguous growable array type, written `Vec<T>` but pronounced 'vector'.
|
||||
///
|
||||
/// # Examples
|
||||
@ -3462,131 +3467,3 @@ unsafe impl<T, A: Allocator> TrustedLen for Drain<'_, T, A> {}
|
||||
|
||||
#[stable(feature = "fused", since = "1.26.0")]
|
||||
impl<T, A: Allocator> FusedIterator for Drain<'_, T, A> {}
|
||||
|
||||
/// A splicing iterator for `Vec`.
|
||||
///
|
||||
/// This struct is created by [`Vec::splice()`].
|
||||
/// See its documentation for more.
|
||||
///
|
||||
/// # Example
|
||||
///
|
||||
/// ```
|
||||
/// let mut v = vec![0, 1, 2];
|
||||
/// let new = [7, 8];
|
||||
/// let iter: std::vec::Splice<_> = v.splice(1.., new.iter().cloned());
|
||||
/// ```
|
||||
#[derive(Debug)]
|
||||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||||
pub struct Splice<
|
||||
'a,
|
||||
I: Iterator + 'a,
|
||||
#[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + 'a = Global,
|
||||
> {
|
||||
drain: Drain<'a, I::Item, A>,
|
||||
replace_with: I,
|
||||
}
|
||||
|
||||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||||
impl<I: Iterator, A: Allocator> Iterator for Splice<'_, I, A> {
|
||||
type Item = I::Item;
|
||||
|
||||
fn next(&mut self) -> Option<Self::Item> {
|
||||
self.drain.next()
|
||||
}
|
||||
|
||||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||||
self.drain.size_hint()
|
||||
}
|
||||
}
|
||||
|
||||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||||
impl<I: Iterator, A: Allocator> DoubleEndedIterator for Splice<'_, I, A> {
|
||||
fn next_back(&mut self) -> Option<Self::Item> {
|
||||
self.drain.next_back()
|
||||
}
|
||||
}
|
||||
|
||||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||||
impl<I: Iterator, A: Allocator> ExactSizeIterator for Splice<'_, I, A> {}
|
||||
|
||||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||||
impl<I: Iterator, A: Allocator> Drop for Splice<'_, I, A> {
|
||||
fn drop(&mut self) {
|
||||
self.drain.by_ref().for_each(drop);
|
||||
|
||||
unsafe {
|
||||
if self.drain.tail_len == 0 {
|
||||
self.drain.vec.as_mut().extend(self.replace_with.by_ref());
|
||||
return;
|
||||
}
|
||||
|
||||
// First fill the range left by drain().
|
||||
if !self.drain.fill(&mut self.replace_with) {
|
||||
return;
|
||||
}
|
||||
|
||||
// There may be more elements. Use the lower bound as an estimate.
|
||||
// FIXME: Is the upper bound a better guess? Or something else?
|
||||
let (lower_bound, _upper_bound) = self.replace_with.size_hint();
|
||||
if lower_bound > 0 {
|
||||
self.drain.move_tail(lower_bound);
|
||||
if !self.drain.fill(&mut self.replace_with) {
|
||||
return;
|
||||
}
|
||||
}
|
||||
|
||||
// Collect any remaining elements.
|
||||
// This is a zero-length vector which does not allocate if `lower_bound` was exact.
|
||||
let mut collected = self.replace_with.by_ref().collect::<Vec<I::Item>>().into_iter();
|
||||
// Now we have an exact count.
|
||||
if collected.len() > 0 {
|
||||
self.drain.move_tail(collected.len());
|
||||
let filled = self.drain.fill(&mut collected);
|
||||
debug_assert!(filled);
|
||||
debug_assert_eq!(collected.len(), 0);
|
||||
}
|
||||
}
|
||||
// Let `Drain::drop` move the tail back if necessary and restore `vec.len`.
|
||||
}
|
||||
}
|
||||
|
||||
/// Private helper methods for `Splice::drop`
|
||||
impl<T, A: Allocator> Drain<'_, T, A> {
|
||||
/// The range from `self.vec.len` to `self.tail_start` contains elements
|
||||
/// that have been moved out.
|
||||
/// Fill that range as much as possible with new elements from the `replace_with` iterator.
|
||||
/// Returns `true` if we filled the entire range. (`replace_with.next()` didn’t return `None`.)
|
||||
unsafe fn fill<I: Iterator<Item = T>>(&mut self, replace_with: &mut I) -> bool {
|
||||
let vec = unsafe { self.vec.as_mut() };
|
||||
let range_start = vec.len;
|
||||
let range_end = self.tail_start;
|
||||
let range_slice = unsafe {
|
||||
slice::from_raw_parts_mut(vec.as_mut_ptr().add(range_start), range_end - range_start)
|
||||
};
|
||||
|
||||
for place in range_slice {
|
||||
if let Some(new_item) = replace_with.next() {
|
||||
unsafe { ptr::write(place, new_item) };
|
||||
vec.len += 1;
|
||||
} else {
|
||||
return false;
|
||||
}
|
||||
}
|
||||
true
|
||||
}
|
||||
|
||||
/// Makes room for inserting more elements before the tail.
|
||||
unsafe fn move_tail(&mut self, additional: usize) {
|
||||
let vec = unsafe { self.vec.as_mut() };
|
||||
let len = self.tail_start + self.tail_len;
|
||||
vec.buf.reserve(len, additional);
|
||||
|
||||
let new_tail_start = self.tail_start + additional;
|
||||
unsafe {
|
||||
let src = vec.as_ptr().add(self.tail_start);
|
||||
let dst = vec.as_mut_ptr().add(new_tail_start);
|
||||
ptr::copy(src, dst, self.tail_len);
|
||||
}
|
||||
self.tail_start = new_tail_start;
|
||||
}
|
||||
}
|
||||
|
||||
133
library/alloc/src/vec/splice.rs
Normal file
133
library/alloc/src/vec/splice.rs
Normal file
@ -0,0 +1,133 @@
|
||||
use crate::alloc::{Allocator, Global};
|
||||
use core::ptr::{self};
|
||||
use core::slice::{self};
|
||||
|
||||
use super::{Vec, Drain};
|
||||
|
||||
/// A splicing iterator for `Vec`.
|
||||
///
|
||||
/// This struct is created by [`Vec::splice()`].
|
||||
/// See its documentation for more.
|
||||
///
|
||||
/// # Example
|
||||
///
|
||||
/// ```
|
||||
/// let mut v = vec![0, 1, 2];
|
||||
/// let new = [7, 8];
|
||||
/// let iter: std::vec::Splice<_> = v.splice(1.., new.iter().cloned());
|
||||
/// ```
|
||||
#[derive(Debug)]
|
||||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||||
pub struct Splice<
|
||||
'a,
|
||||
I: Iterator + 'a,
|
||||
#[unstable(feature = "allocator_api", issue = "32838")] A: Allocator + 'a = Global,
|
||||
> {
|
||||
pub(super) drain: Drain<'a, I::Item, A>,
|
||||
pub(super) replace_with: I,
|
||||
}
|
||||
|
||||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||||
impl<I: Iterator, A: Allocator> Iterator for Splice<'_, I, A> {
|
||||
type Item = I::Item;
|
||||
|
||||
fn next(&mut self) -> Option<Self::Item> {
|
||||
self.drain.next()
|
||||
}
|
||||
|
||||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||||
self.drain.size_hint()
|
||||
}
|
||||
}
|
||||
|
||||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||||
impl<I: Iterator, A: Allocator> DoubleEndedIterator for Splice<'_, I, A> {
|
||||
fn next_back(&mut self) -> Option<Self::Item> {
|
||||
self.drain.next_back()
|
||||
}
|
||||
}
|
||||
|
||||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||||
impl<I: Iterator, A: Allocator> ExactSizeIterator for Splice<'_, I, A> {}
|
||||
|
||||
#[stable(feature = "vec_splice", since = "1.21.0")]
|
||||
impl<I: Iterator, A: Allocator> Drop for Splice<'_, I, A> {
|
||||
fn drop(&mut self) {
|
||||
self.drain.by_ref().for_each(drop);
|
||||
|
||||
unsafe {
|
||||
if self.drain.tail_len == 0 {
|
||||
self.drain.vec.as_mut().extend(self.replace_with.by_ref());
|
||||
return;
|
||||
}
|
||||
|
||||
// First fill the range left by drain().
|
||||
if !self.drain.fill(&mut self.replace_with) {
|
||||
return;
|
||||
}
|
||||
|
||||
// There may be more elements. Use the lower bound as an estimate.
|
||||
// FIXME: Is the upper bound a better guess? Or something else?
|
||||
let (lower_bound, _upper_bound) = self.replace_with.size_hint();
|
||||
if lower_bound > 0 {
|
||||
self.drain.move_tail(lower_bound);
|
||||
if !self.drain.fill(&mut self.replace_with) {
|
||||
return;
|
||||
}
|
||||
}
|
||||
|
||||
// Collect any remaining elements.
|
||||
// This is a zero-length vector which does not allocate if `lower_bound` was exact.
|
||||
let mut collected = self.replace_with.by_ref().collect::<Vec<I::Item>>().into_iter();
|
||||
// Now we have an exact count.
|
||||
if collected.len() > 0 {
|
||||
self.drain.move_tail(collected.len());
|
||||
let filled = self.drain.fill(&mut collected);
|
||||
debug_assert!(filled);
|
||||
debug_assert_eq!(collected.len(), 0);
|
||||
}
|
||||
}
|
||||
// Let `Drain::drop` move the tail back if necessary and restore `vec.len`.
|
||||
}
|
||||
}
|
||||
|
||||
/// Private helper methods for `Splice::drop`
|
||||
impl<T, A: Allocator> Drain<'_, T, A> {
|
||||
/// The range from `self.vec.len` to `self.tail_start` contains elements
|
||||
/// that have been moved out.
|
||||
/// Fill that range as much as possible with new elements from the `replace_with` iterator.
|
||||
/// Returns `true` if we filled the entire range. (`replace_with.next()` didn’t return `None`.)
|
||||
unsafe fn fill<I: Iterator<Item = T>>(&mut self, replace_with: &mut I) -> bool {
|
||||
let vec = unsafe { self.vec.as_mut() };
|
||||
let range_start = vec.len;
|
||||
let range_end = self.tail_start;
|
||||
let range_slice = unsafe {
|
||||
slice::from_raw_parts_mut(vec.as_mut_ptr().add(range_start), range_end - range_start)
|
||||
};
|
||||
|
||||
for place in range_slice {
|
||||
if let Some(new_item) = replace_with.next() {
|
||||
unsafe { ptr::write(place, new_item) };
|
||||
vec.len += 1;
|
||||
} else {
|
||||
return false;
|
||||
}
|
||||
}
|
||||
true
|
||||
}
|
||||
|
||||
/// Makes room for inserting more elements before the tail.
|
||||
unsafe fn move_tail(&mut self, additional: usize) {
|
||||
let vec = unsafe { self.vec.as_mut() };
|
||||
let len = self.tail_start + self.tail_len;
|
||||
vec.buf.reserve(len, additional);
|
||||
|
||||
let new_tail_start = self.tail_start + additional;
|
||||
unsafe {
|
||||
let src = vec.as_ptr().add(self.tail_start);
|
||||
let dst = vec.as_mut_ptr().add(new_tail_start);
|
||||
ptr::copy(src, dst, self.tail_len);
|
||||
}
|
||||
self.tail_start = new_tail_start;
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user