use core::ops::{Deref, DerefMut};
use core::ptr;
+use crate::collections::TryReserveError;
use crate::slice;
use crate::vec::{self, AsIntoIter, Vec};
self.data.reserve(additional);
}
+ /// Tries to reserve the minimum capacity for exactly `additional`
+ /// elements to be inserted in the given `BinaryHeap<T>`. After calling
+ /// `try_reserve_exact`, capacity will be greater than or equal to
+ /// `self.len() + additional` if it returns `Ok(())`.
+ /// Does nothing if the capacity is already sufficient.
+ ///
+ /// Note that the allocator may give the collection more space than it
+ /// requests. Therefore, capacity can not be relied upon to be precisely
+ /// minimal. Prefer [`try_reserve`] if future insertions are expected.
+ ///
+ /// [`try_reserve`]: BinaryHeap::try_reserve
+ ///
+ /// # Errors
+ ///
+ /// If the capacity overflows, or the allocator reports a failure, then an error
+ /// is returned.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// #![feature(try_reserve_binary_heap)]
+ /// use std::collections::BinaryHeap;
+ /// use std::collections::TryReserveError;
+ ///
+ /// fn find_max_slow(data: &[u32]) -> Result<Option<u32>, TryReserveError> {
+ /// let mut heap = BinaryHeap::new();
+ ///
+ /// // Pre-reserve the memory, exiting if we can't
+ /// heap.try_reserve_exact(data.len())?;
+ ///
+ /// // Now we know this can't OOM in the middle of our complex work
+ /// heap.extend(data.iter());
+ ///
+ /// Ok(heap.pop())
+ /// }
+ /// # find_max_slow(&[1, 2, 3]).expect("why is the test harness OOMing on 12 bytes?");
+ /// ```
+ #[unstable(feature = "try_reserve_binary_heap", issue = "none")]
+ pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), TryReserveError> {
+ self.data.try_reserve_exact(additional)
+ }
+
+ /// Tries to reserve capacity for at least `additional` more elements to be inserted
+ /// in the given `BinaryHeap<T>`. The collection may reserve more space to avoid
+ /// frequent reallocations. After calling `try_reserve`, capacity will be
+ /// greater than or equal to `self.len() + additional`. Does nothing if
+ /// capacity is already sufficient.
+ ///
+ /// # Errors
+ ///
+ /// If the capacity overflows, or the allocator reports a failure, then an error
+ /// is returned.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// #![feature(try_reserve_binary_heap)]
+ /// use std::collections::BinaryHeap;
+ /// use std::collections::TryReserveError;
+ ///
+ /// fn find_max_slow(data: &[u32]) -> Result<Option<u32>, TryReserveError> {
+ /// let mut heap = BinaryHeap::new();
+ ///
+ /// // Pre-reserve the memory, exiting if we can't
+ /// heap.try_reserve(data.len())?;
+ ///
+ /// // Now we know this can't OOM in the middle of our complex work
+ /// heap.extend(data.iter());
+ ///
+ /// Ok(heap.pop())
+ /// }
+ /// # find_max_slow(&[1, 2, 3]).expect("why is the test harness OOMing on 12 bytes?");
+ /// ```
+ #[unstable(feature = "try_reserve_binary_heap", issue = "none")]
+ pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> {
+ self.data.try_reserve(additional)
+ }
+
/// Discards as much additional capacity as possible.
///
/// # Examples