本系列錄製的影片主要放在B站上Rust死靈書學習影片
Rust 死靈書相關的原始碼資料在github.com/anonymousGiga/Rustonomi...
本節主要對之前實現的MyVec進行測試,程式碼如下:
#![feature(ptr_internals)]
use std::mem;
use std::alloc::{alloc, realloc, dealloc, Layout, handle_alloc_error};
use std::ptr::{Unique, self};
use std::ops::{Deref, DerefMut};
use std::slice;
#[derive(Debug)]
struct RawVec<T> {
ptr: Unique<T>,
cap: usize,
}
impl<T> RawVec<T> {
fn new() -> Self {
//assert!(mem::size_of::<T>() != 0, "還沒準備好處理零尺寸型別");
let cap = if mem::size_of::<T>() == 0 { !0 } else { 0 };
RawVec { ptr: Unique::dangling(), cap: cap }
}
fn grow(&mut self) {
unsafe {
let align = mem::align_of::<T>();
let elem_size = mem::size_of::<T>();
assert!(elem_size != 0, "capacity overflow");
let layout: Layout;
let (new_cap, ptr) = if self.cap == 0 {
layout = Layout::from_size_align_unchecked(elem_size, align);
let ptr = alloc(layout);
(1, ptr)
} else {
let new_cap = self.cap * 2;
let old_num_bytes = self.cap * elem_size;
assert!(old_num_bytes <= (isize::MAX as usize) / 2,
"capacity overflow");
let new_num_bytes = old_num_bytes * 2;
layout = Layout::from_size_align_unchecked(new_num_bytes, align);
let ptr = realloc(self.ptr.as_ptr() as *mut _,
layout,
new_num_bytes);
(new_cap, ptr)
};
if ptr.is_null() { handle_alloc_error(layout); }
if let Some(ptr) = Unique::new(ptr as *mut _) {
self.ptr = ptr;
} else {
panic!("error!");
}
self.cap = new_cap;
}
}
}
impl<T> Drop for RawVec<T> {
fn drop(&mut self) {
let elem_size = mem::size_of::<T>();
if self.cap != 0 && elem_size != 0 {
let align = mem::align_of::<T>();
let elem_size = mem::size_of::<T>();
let num_bytes = elem_size * self.cap;
unsafe {
let layout: Layout = Layout::from_size_align_unchecked(num_bytes, align);
dealloc(self.ptr.as_ptr() as *mut _, layout)
}
println!("release memory in drop function!");
}
}
}
struct IntoIter<T> {
_buf: RawVec<T>,
iter: RawValIter<T>,
}
impl<T> Drop for IntoIter<T> {
fn drop(&mut self) {
for _ in &mut *self {}
}
}
#[derive(Debug)]
pub struct MyVec<T> {
buf: RawVec<T>,
len: usize,
}
impl<T> MyVec<T> {
fn ptr(&self) -> *mut T {
self.buf.ptr.as_ptr()
}
fn cap(&self) -> usize {
self.buf.cap
}
pub fn new() -> Self {
MyVec { buf: RawVec::new(), len: 0 }
}
fn push(&mut self, elem: T) {
if self.len == self.cap() {
self.buf.grow();
}
//關鍵點在於要直接覆蓋,因為不知道記憶體之前是否有東西
unsafe {
ptr::write(self.ptr().offset(self.len as isize), elem);
}
self.len += 1;
}
fn pop(&mut self) -> Option<T> {
if self.len == 0 {
None
} else {
self.len -= 1;
unsafe {
Some(ptr::read(self.ptr().offset(self.len as isize)))
}
}
}
fn insert(&mut self, index: usize, elem: T) {
assert!(index <= self.len, "越界");
if self.cap() == self.len {
self.buf.grow();
}
unsafe {
if index < self.len {
ptr::copy(self.ptr().offset(index as isize),
self.ptr().offset((index as isize) + 1),
self.len - index);
}
ptr::write(self.ptr().offset(index as isize), elem);
self.len += 1;
}
}
fn remove(&mut self, index: usize) -> T {
assert!(index < self.len, "越界");
unsafe {
self.len -= 1;
let result = ptr::read(self.ptr().offset(index as isize));
ptr::copy(self.ptr().offset(index as isize + 1),
self.ptr().offset(index as isize),
self.len - index);
result
}
}
fn into_iter(self) -> IntoIter<T> {
unsafe {
let iter = RawValIter::new(&self);
let buf = ptr::read(&self.buf);
mem::forget(self);
IntoIter {
iter: iter,
_buf: buf,
}
}
}
}
impl<T> Drop for MyVec<T> {
fn drop(&mut self) {
while let Some(_) = self.pop() {}
}
}
impl<T> Deref for MyVec<T> {
type Target = [T];
fn deref(&self) -> &[T] {
unsafe {
slice::from_raw_parts(self.buf.ptr.as_ptr(), self.len)
}
}
}
impl<T> DerefMut for MyVec<T> {
fn deref_mut(&mut self) -> &mut [T] {
unsafe {
slice::from_raw_parts_mut(self.buf.ptr.as_ptr(), self.len)
}
}
}
//為IntoIter實現迭代器
impl<T> Iterator for IntoIter<T> {
type Item = T;
fn next(&mut self) -> Option<T> {
self.iter.next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
impl<T> DoubleEndedIterator for IntoIter<T> {
fn next_back(&mut self) -> Option<T> {
self.iter.next_back()
}
}
struct RawValIter<T> {
start: *const T,
end: *const T,
}
impl<T> RawValIter<T> {
unsafe fn new(slice: &[T]) -> Self {
RawValIter {
start: slice.as_ptr(),
end: if mem::size_of::<T>() == 0 {
((slice.as_ptr() as usize) + slice.len()) as *const _
} else if slice.len() == 0 {
slice.as_ptr()
} else {
slice.as_ptr().offset(slice.len() as isize)
}
}
}
}
impl<T> Iterator for RawValIter<T> {
type Item = T;
fn next(&mut self) -> Option<T> {
if self.start == self.end {
None
} else {
unsafe {
let result = ptr::read(self.start);
self.start = if mem::size_of::<T>() == 0 {
(self.start as usize + 1) as *const _
} else {
self.start.offset(1)
};
Some(result)
}
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
let elem_size = mem::size_of::<T>();
let len = (self.end as usize - self.start as usize)
/ if elem_size == 0 { 0 } else { elem_size };
(len, Some(len))
}
}
impl<T> DoubleEndedIterator for RawValIter<T> {
fn next_back(&mut self) -> Option<T> {
if self.start == self.end {
None
} else {
unsafe {
self.end = if mem::size_of::<T>() == 0 {
(self.end as usize - 1) as *const _
} else {
self.end.offset(-1)
};
Some(ptr::read(self.end))
}
}
}
}
use std::marker::PhantomData;
//Drain是一個API集合,將容器內資料的所有權移出,卻不佔有容器本身
struct Drain<'a, T: 'a> {
vec: PhantomData<&'a mut MyVec<T>>,
iter: RawValIter<T>,
}
impl<'a, T> Iterator for Drain<'a, T> {
type Item = T;
fn next(&mut self) -> Option<T> {
self.iter.next()
}
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
impl<'a, T> DoubleEndedIterator for Drain<'a, T> {
fn next_back(&mut self) -> Option<T> { self.iter.next_back() }
}
impl<'a, T> Drop for Drain<'a, T> {
fn drop(&mut self) {
for _ in &mut self.iter {}
}
}
impl<T> MyVec<T> {
fn drain(&mut self) -> Drain<T> {
unsafe {
let iter = RawValIter::new(&self);
self.len = 0;
Drain {
iter: iter,
vec: PhantomData,
}
}
}
}
fn main() {
tests::create_push_pop();
tests::iter_test();
tests::test_drain();
tests::test_zst();
println!("All tests finished OK");
}
mod tests {
use crate::MyVec;
pub fn create_push_pop() {
let mut v = MyVec::new();
v.push(1);
assert_eq!(1, v.len());
assert_eq!(1, v[0]);
for i in v.iter_mut() {
*i += 1;
}
v.insert(0, 5);
let x = v.pop();
assert_eq!(Some(2), x);
assert_eq!(1, v.len());
v.push(10);
let x = v.remove(0);
assert_eq!(5, x);
assert_eq!(1, v.len());
}
pub fn iter_test() {
let mut v = MyVec::new();
for i in 0..10 {
v.push(Box::new(i))
}
let mut iter = v.into_iter();
let first = iter.next().unwrap();
let last = iter.next_back().unwrap();
drop(iter);
assert_eq!(0, *first);
assert_eq!(9, *last);
}
pub fn test_drain() {
let mut v = MyVec::new();
for i in 0..10 {
v.push(Box::new(i))
}
{
let mut drain = v.drain();
let first = drain.next().unwrap();
let last = drain.next_back().unwrap();
assert_eq!(0, *first);
assert_eq!(9, *last);
}
assert_eq!(0, v.len());
v.push(Box::new(1));
assert_eq!(1, *v.pop().unwrap());
}
pub fn test_zst() {
let mut v = MyVec::new();
for _i in 0..10 {
v.push(())
}
let mut count = 0;
for _ in v.into_iter() {
count += 1
}
assert_eq!(10, count);
}
}
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