<!DOCTYPE HTML> <html lang="en"> <head> <meta charset="UTF-8"> <title>Final Code - </title> <meta content="text/html; charset=utf-8" http-equiv="Content-Type"> <meta name="description" content=""> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="theme-color" content="#ffffff" /> <base href=""> <link rel="stylesheet" href="book.css"> <link href="https://fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,700italic,800italic,400,300,600,700,800" rel="stylesheet" type="text/css"> <link href="https://fonts.googleapis.com/css?family=Source+Code+Pro:500" rel="stylesheet" type="text/css"> <link rel="shortcut icon" href="favicon.png"> <!-- Font Awesome --> <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.3.0/css/font-awesome.min.css"> <link rel="stylesheet" href="highlight.css"> <link rel="stylesheet" href="tomorrow-night.css"> <link rel="stylesheet" href="ayu-highlight.css"> <!-- Custom theme --> <!-- Fetch 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href="working-with-unsafe.html"><strong aria-hidden="true">1.3.</strong> Working with Unsafe</a></li></ol></li><li><a href="data.html"><strong aria-hidden="true">2.</strong> Data Layout</a></li><li><ol class="section"><li><a href="repr-rust.html"><strong aria-hidden="true">2.1.</strong> repr(Rust)</a></li><li><a href="exotic-sizes.html"><strong aria-hidden="true">2.2.</strong> Exotically Sized Types</a></li><li><a href="other-reprs.html"><strong aria-hidden="true">2.3.</strong> Other reprs</a></li></ol></li><li><a href="ownership.html"><strong aria-hidden="true">3.</strong> Ownership</a></li><li><ol class="section"><li><a href="references.html"><strong aria-hidden="true">3.1.</strong> References</a></li><li><a href="aliasing.html"><strong aria-hidden="true">3.2.</strong> Aliasing</a></li><li><a href="lifetimes.html"><strong aria-hidden="true">3.3.</strong> Lifetimes</a></li><li><a href="lifetime-mismatch.html"><strong aria-hidden="true">3.4.</strong> Limits of Lifetimes</a></li><li><a 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Operator</a></li><li><a href="casts.html"><strong aria-hidden="true">4.3.</strong> Casts</a></li><li><a href="transmutes.html"><strong aria-hidden="true">4.4.</strong> Transmutes</a></li></ol></li><li><a href="uninitialized.html"><strong aria-hidden="true">5.</strong> Uninitialized Memory</a></li><li><ol class="section"><li><a href="checked-uninit.html"><strong aria-hidden="true">5.1.</strong> Checked</a></li><li><a href="drop-flags.html"><strong aria-hidden="true">5.2.</strong> Drop Flags</a></li><li><a href="unchecked-uninit.html"><strong aria-hidden="true">5.3.</strong> Unchecked</a></li></ol></li><li><a href="obrm.html"><strong aria-hidden="true">6.</strong> Ownership Based Resource Management</a></li><li><ol class="section"><li><a href="constructors.html"><strong aria-hidden="true">6.1.</strong> Constructors</a></li><li><a href="destructors.html"><strong aria-hidden="true">6.2.</strong> Destructors</a></li><li><a href="leaking.html"><strong aria-hidden="true">6.3.</strong> Leaking</a></li></ol></li><li><a href="unwinding.html"><strong aria-hidden="true">7.</strong> Unwinding</a></li><li><ol class="section"><li><a href="exception-safety.html"><strong aria-hidden="true">7.1.</strong> Exception Safety</a></li><li><a href="poisoning.html"><strong aria-hidden="true">7.2.</strong> Poisoning</a></li></ol></li><li><a href="concurrency.html"><strong aria-hidden="true">8.</strong> Concurrency</a></li><li><ol class="section"><li><a href="races.html"><strong aria-hidden="true">8.1.</strong> Races</a></li><li><a href="send-and-sync.html"><strong aria-hidden="true">8.2.</strong> Send and Sync</a></li><li><a href="atomics.html"><strong aria-hidden="true">8.3.</strong> Atomics</a></li></ol></li><li><a href="vec.html"><strong aria-hidden="true">9.</strong> Implementing Vec</a></li><li><ol class="section"><li><a href="vec-layout.html"><strong aria-hidden="true">9.1.</strong> Layout</a></li><li><a href="vec-alloc.html"><strong aria-hidden="true">9.2.</strong> Allocating</a></li><li><a href="vec-push-pop.html"><strong aria-hidden="true">9.3.</strong> Push and Pop</a></li><li><a href="vec-dealloc.html"><strong aria-hidden="true">9.4.</strong> Deallocating</a></li><li><a href="vec-deref.html"><strong aria-hidden="true">9.5.</strong> Deref</a></li><li><a href="vec-insert-remove.html"><strong aria-hidden="true">9.6.</strong> Insert and Remove</a></li><li><a href="vec-into-iter.html"><strong aria-hidden="true">9.7.</strong> IntoIter</a></li><li><a href="vec-raw.html"><strong aria-hidden="true">9.8.</strong> RawVec</a></li><li><a href="vec-drain.html"><strong aria-hidden="true">9.9.</strong> Drain</a></li><li><a href="vec-zsts.html"><strong aria-hidden="true">9.10.</strong> Handling Zero-Sized Types</a></li><li><a href="vec-final.html" class="active"><strong aria-hidden="true">9.11.</strong> Final Code</a></li></ol></li><li><a href="arc-and-mutex.html"><strong aria-hidden="true">10.</strong> Implementing Arc and Mutex</a></li><li><a href="ffi.html"><strong aria-hidden="true">11.</strong> FFI</a></li></ol> </nav> <div id="page-wrapper" class="page-wrapper"> <div class="page"> <div id="menu-bar" class="menu-bar"> <div id="menu-bar-sticky-container"> <div class="left-buttons"> <button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar"> <i class="fa fa-bars"></i> </button> <button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list"> <i class="fa fa-paint-brush"></i> </button> <ul id="theme-list" class="theme-popup" aria-label="submenu"> <li><button class="theme" id="light">Light <span class="default">(default)</span></button></li> <li><button class="theme" id="rust">Rust</button></li> <li><button class="theme" id="coal">Coal</button></li> <li><button class="theme" id="navy">Navy</button></li> <li><button 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std::ptr::{Unique, self}; use std::mem; use std::ops::{Deref, DerefMut}; use std::marker::PhantomData; use std::heap::{Alloc, Layout, Heap}; struct RawVec<T> { ptr: Unique<T>, cap: usize, } impl<T> RawVec<T> { fn new() -> Self { // !0 is usize::MAX. This branch should be stripped at compile time. let cap = if mem::size_of::<T>() == 0 { !0 } else { 0 }; // Unique::empty() doubles as "unallocated" and "zero-sized allocation" RawVec { ptr: Unique::empty(), cap: cap } } fn grow(&mut self) { unsafe { let elem_size = mem::size_of::<T>(); // since we set the capacity to usize::MAX when elem_size is // 0, getting to here necessarily means the Vec is overfull. assert!(elem_size != 0, "capacity overflow"); let (new_cap, ptr) = if self.cap == 0 { let ptr = Heap.alloc(Layout::array::<T>(1).unwrap()); (1, ptr) } else { let new_cap = 2 * self.cap; let ptr = Heap.realloc(self.ptr.as_ptr() as *mut _, Layout::array::<T>(self.cap).unwrap(), Layout::array::<T>(new_cap).unwrap()); (new_cap, ptr) }; // If allocate or reallocate fail, oom let ptr = match ptr { Ok(ptr) => ptr, Err(err) => Heap.oom(err), }; self.ptr = Unique::new_unchecked(ptr as *mut _); 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 { unsafe { Heap.dealloc(self.ptr.as_ptr() as *mut _, Layout::array::<T>(self.cap).unwrap()); } } } } pub struct Vec<T> { buf: RawVec<T>, len: usize, } impl<T> Vec<T> { fn ptr(&self) -> *mut T { self.buf.ptr.as_ptr() } fn cap(&self) -> usize { self.buf.cap } pub fn new() -> Self { Vec { buf: RawVec::new(), len: 0 } } pub fn push(&mut self, elem: T) { if self.len == self.cap() { self.buf.grow(); } unsafe { ptr::write(self.ptr().offset(self.len as isize), elem); } // Can't fail, we'll OOM first. self.len += 1; } pub 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))) } } } pub fn insert(&mut self, index: usize, elem: T) { assert!(index <= self.len, "index out of bounds"); 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; } } pub fn remove(&mut self, index: usize) -> T { assert!(index < self.len, "index out of bounds"); 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 } } pub 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, } } } pub fn drain(&mut self) -> Drain<T> { unsafe { let iter = RawValIter::new(&self); // this is a mem::forget safety thing. If Drain is forgotten, we just // leak the whole Vec's contents. Also we need to do this *eventually* // anyway, so why not do it now? self.len = 0; Drain { iter: iter, vec: PhantomData, } } } } impl<T> Drop for Vec<T> { fn drop(&mut self) { while let Some(_) = self.pop() {} // allocation is handled by RawVec } } impl<T> Deref for Vec<T> { type Target = [T]; fn deref(&self) -> &[T] { unsafe { ::std::slice::from_raw_parts(self.ptr(), self.len) } } } impl<T> DerefMut for Vec<T> { fn deref_mut(&mut self) -> &mut [T] { unsafe { ::std::slice::from_raw_parts_mut(self.ptr(), self.len) } } } 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 { 1 } 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)) } } } } pub struct IntoIter<T> { _buf: RawVec<T>, // we don't actually care about this. Just need it to live. iter: RawValIter<T>, } 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() } } impl<T> Drop for IntoIter<T> { fn drop(&mut self) { for _ in &mut *self {} } } pub struct Drain<'a, T: 'a> { vec: PhantomData<&'a mut Vec<T>>, iter: RawValIter<T>, } impl<'a, T> Iterator for Drain<'a, T> { type Item = T; fn next(&mut self) -> Option<T> { self.iter.next_back() } 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) { // pre-drain the iter for _ in &mut self.iter {} } } /// Abort the process, we're out of memory! /// /// In practice this is probably dead code on most OSes fn oom() { ::std::process::exit(-9999); } # fn main() {} </code></pre></pre> </main> <nav class="nav-wrapper" aria-label="Page navigation"> <!-- Mobile navigation buttons --> <a rel="prev" href="vec-zsts.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> <a rel="next" href="arc-and-mutex.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> <div style="clear: both"></div> </nav> </div> </div> <nav class="nav-wide-wrapper" aria-label="Page navigation"> <a href="vec-zsts.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> <a href="arc-and-mutex.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> </nav> </div> <!-- Local fallback for Font Awesome --> <script> if (getComputedStyle(document.querySelector(".fa")).fontFamily !== "FontAwesome") { var link = document.createElement('link'); link.rel = 'stylesheet'; link.type = 'text/css'; link.href = '_FontAwesome/css/font-awesome.css'; document.head.insertBefore(link, document.head.firstChild) } </script> <script src="highlight.js"></script> <script src="book.js"></script> <!-- Custom JS script --> </body> </html>