add code examples · rust-lang/rust@a85ee3e (original) (raw)
`@@ -557,6 +557,32 @@ impl Vec {
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`/// assert_eq!(rebuilt, [4, 5, 6]);
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`/// }
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```` /// ```
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///
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/// Using memory that was allocated elsewhere:
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///
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/// ```rust
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/// #![feature(allocator_api)]
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///
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/// use std::alloc::{AllocError, Allocator, Global, Layout};
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///
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/// fn main() {
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/// let layout = Layout::array::(16).expect("overflow cannot happen");
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///
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/// let vec = unsafe {
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/// let mem = match Global.allocate(layout) {
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/// Ok(mem) => mem.cast::().as_ptr(),
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/// Err(AllocError) => return,
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/// };
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///
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/// mem.write(1_000_000);
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///
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/// Vec::from_raw_parts_in(mem, 1, 16, Global)
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/// };
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///
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/// assert_eq!(vec, &[1_000_000]);
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/// assert_eq!(vec.capacity(), 16);
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/// }
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/// ```
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`#[inline]
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`#[stable(feature = "rust1", since = "1.0.0")]
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`pub unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Self {
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`@@ -669,7 +695,7 @@ impl<T, A: Allocator> Vec<T, A> {
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`` /// See the safety documentation of [pointer::offset].
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`///
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`` /// These requirements are always upheld by any ptr that has been allocated
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/// via Vec<T>. Other allocation sources are allowed if the invariants are
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/// via Vec<T, A>. Other allocation sources are allowed if the invariants are
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`/// upheld.
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`///
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`/// Violating these may cause problems like corrupting the allocator's
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`@@ -727,6 +753,29 @@ impl<T, A: Allocator> Vec<T, A> {
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`/// assert_eq!(rebuilt, [4, 5, 6]);
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`/// }
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```` /// ```
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///
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/// Using memory that was allocated elsewhere:
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///
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/// ```rust
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/// use std::alloc::{alloc, Layout};
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///
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/// fn main() {
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/// let layout = Layout::array::(16).expect("overflow cannot happen");
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/// let vec = unsafe {
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/// let mem = alloc(layout).cast::();
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/// if mem.is_null() {
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/// return;
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/// }
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///
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/// mem.write(1_000_000);
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///
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/// Vec::from_raw_parts(mem, 1, 16)
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/// };
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///
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/// assert_eq!(vec, &[1_000_000]);
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/// assert_eq!(vec.capacity(), 16);
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/// }
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/// ```
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`#[inline]
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`#[unstable(feature = "allocator_api", issue = "32838")]
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`pub unsafe fn from_raw_parts_in(ptr: *mut T, length: usize, capacity: usize, alloc: A) -> Self {
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