Struct heapless::Vec [−][src]
pub struct Vec<T, const N: usize> { /* fields omitted */ }
A fixed capacity Vec
Examples
use heapless::Vec; // A vector with a fixed capacity of 8 elements allocated on the stack let mut vec = Vec::<_, 8>::new(); vec.push(1); vec.push(2); assert_eq!(vec.len(), 2); assert_eq!(vec[0], 1); assert_eq!(vec.pop(), Some(2)); assert_eq!(vec.len(), 1); vec[0] = 7; assert_eq!(vec[0], 7); vec.extend([1, 2, 3].iter().cloned()); for x in &vec { println!("{}", x); } assert_eq!(*vec, [7, 1, 2, 3]);
Implementations
impl<T, const N: usize> Vec<T, N>
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impl<T, const N: usize> Vec<T, N>
[src]pub const fn new() -> Self
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Constructs a new, empty vector with a fixed capacity of N
Examples
use heapless::Vec; // allocate the vector on the stack let mut x: Vec<u8, 16> = Vec::new(); // allocate the vector in a static variable static mut X: Vec<u8, 16> = Vec::new();
Vec
const
constructor; wrap the returned value in Vec
pub fn from_slice(other: &[T]) -> Result<Self, ()> where
T: Clone,
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T: Clone,
Constructs a new vector with a fixed capacity of N
and fills it
with the provided slice.
This is equivalent to the following code:
use heapless::Vec; let mut v: Vec<u8, 16> = Vec::new(); v.extend_from_slice(&[1, 2, 3]).unwrap();
pub fn as_slice(&self) -> &[T]
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Extracts a slice containing the entire vector.
Equivalent to &s[..]
.
Examples
use heapless::Vec; let buffer: Vec<u8, 5> = Vec::from_slice(&[1, 2, 3, 5, 8]).unwrap(); assert_eq!(buffer.as_slice(), &[1, 2, 3, 5, 8]);
pub const fn capacity(&self) -> usize
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Returns the maximum number of elements the vector can hold.
pub fn clear(&mut self)
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Clears the vector, removing all values.
pub fn extend<I>(&mut self, iter: I) where
I: IntoIterator<Item = T>,
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I: IntoIterator<Item = T>,
pub fn extend_from_slice(&mut self, other: &[T]) -> Result<(), ()> where
T: Clone,
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T: Clone,
Clones and appends all elements in a slice to the Vec
.
Iterates over the slice other
, clones each element, and then appends
it to this Vec
. The other
vector is traversed in-order.
Examples
use heapless::Vec; let mut vec = Vec::<u8, 8>::new(); vec.push(1).unwrap(); vec.extend_from_slice(&[2, 3, 4]).unwrap(); assert_eq!(*vec, [1, 2, 3, 4]);
pub fn pop(&mut self) -> Option<T>
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Removes the last element from a vector and returns it, or None
if it’s empty
pub fn push(&mut self, item: T) -> Result<(), T>
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Appends an item
to the back of the collection
Returns back the item
if the vector is full
pub unsafe fn push_unchecked(&mut self, item: T)
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pub fn truncate(&mut self, len: usize)
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Shortens the vector, keeping the first len
elements and dropping the rest.
pub fn resize(&mut self, new_len: usize, value: T) -> Result<(), ()> where
T: Clone,
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T: Clone,
Resizes the Vec in-place so that len is equal to new_len.
If new_len is greater than len, the Vec is extended by the difference, with each additional slot filled with value. If new_len is less than len, the Vec is simply truncated.
See also resize_default
.
pub fn resize_default(&mut self, new_len: usize) -> Result<(), ()> where
T: Clone + Default,
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T: Clone + Default,
Resizes the Vec
in-place so that len
is equal to new_len
.
If new_len
is greater than len
, the Vec
is extended by the
difference, with each additional slot filled with Default::default()
.
If new_len
is less than len
, the Vec
is simply truncated.
See also resize
.
pub unsafe fn set_len(&mut self, new_len: usize)
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Forces the length of the vector to new_len
.
This is a low-level operation that maintains none of the normal
invariants of the type. Normally changing the length of a vector
is done using one of the safe operations instead, such as
truncate
, resize
, extend
, or clear
.
Safety
new_len
must be less than or equal tocapacity()
.- The elements at
old_len..new_len
must be initialized.
Examples
This method can be useful for situations in which the vector is serving as a buffer for other code, particularly over FFI:
use heapless::Vec; pub fn get_dictionary(&self) -> Option<Vec<u8, 32768>> { // Per the FFI method's docs, "32768 bytes is always enough". let mut dict = Vec::new(); let mut dict_length = 0; // SAFETY: When `deflateGetDictionary` returns `Z_OK`, it holds that: // 1. `dict_length` elements were initialized. // 2. `dict_length` <= the capacity (32_768) // which makes `set_len` safe to call. unsafe { // Make the FFI call... let r = deflateGetDictionary(self.strm, dict.as_mut_ptr(), &mut dict_length); if r == Z_OK { // ...and update the length to what was initialized. dict.set_len(dict_length); Some(dict) } else { None } } }
While the following example is sound, there is a memory leak since
the inner vectors were not freed prior to the set_len
call:
use core::iter::FromIterator; use heapless::Vec; let mut vec = Vec::<Vec<u8, 3>, 3>::from_iter( [ Vec::from_iter([1, 0, 0].iter().cloned()), Vec::from_iter([0, 1, 0].iter().cloned()), Vec::from_iter([0, 0, 1].iter().cloned()), ] .iter() .cloned() ); // SAFETY: // 1. `old_len..0` is empty so no elements need to be initialized. // 2. `0 <= capacity` always holds whatever `capacity` is. unsafe { vec.set_len(0); }
Normally, here, one would use clear
instead to correctly drop
the contents and thus not leak memory.
pub fn swap_remove(&mut self, index: usize) -> T
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Removes an element from the vector and returns it.
The removed element is replaced by the last element of the vector.
This does not preserve ordering, but is O(1).
Panics
Panics if index
is out of bounds.
Examples
use heapless::Vec; let mut v: Vec<_, 8> = Vec::new(); v.push("foo").unwrap(); v.push("bar").unwrap(); v.push("baz").unwrap(); v.push("qux").unwrap(); assert_eq!(v.swap_remove(1), "bar"); assert_eq!(&*v, ["foo", "qux", "baz"]); assert_eq!(v.swap_remove(0), "foo"); assert_eq!(&*v, ["baz", "qux"]);
pub unsafe fn swap_remove_unchecked(&mut self, index: usize) -> T
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Removes an element from the vector and returns it.
The removed element is replaced by the last element of the vector.
This does not preserve ordering, but is O(1).
Safety
Assumes index
within bounds.
Examples
use heapless::Vec; let mut v: Vec<_, 8> = Vec::new(); v.push("foo").unwrap(); v.push("bar").unwrap(); v.push("baz").unwrap(); v.push("qux").unwrap(); assert_eq!(unsafe { v.swap_remove_unchecked(1) }, "bar"); assert_eq!(&*v, ["foo", "qux", "baz"]); assert_eq!(unsafe { v.swap_remove_unchecked(0) }, "foo"); assert_eq!(&*v, ["baz", "qux"]);
pub fn is_full(&self) -> bool
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Returns true if the vec is full
pub fn starts_with(&self, needle: &[T]) -> bool where
T: PartialEq,
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T: PartialEq,
Returns true
if needle
is a prefix of the Vec.
Always returns true
if needle
is an empty slice.
Examples
use heapless::Vec; let v: Vec<_, 8> = Vec::from_slice(b"abc").unwrap(); assert_eq!(v.starts_with(b""), true); assert_eq!(v.starts_with(b"ab"), true); assert_eq!(v.starts_with(b"bc"), false);
pub fn ends_with(&self, needle: &[T]) -> bool where
T: PartialEq,
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T: PartialEq,
Returns true
if needle
is a suffix of the Vec.
Always returns true
if needle
is an empty slice.
Examples
use heapless::Vec; let v: Vec<_, 8> = Vec::from_slice(b"abc").unwrap(); assert_eq!(v.ends_with(b""), true); assert_eq!(v.ends_with(b"ab"), false); assert_eq!(v.ends_with(b"bc"), true);
Trait Implementations
impl<T, const N: usize> Clone for Vec<T, N> where
T: Clone,
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impl<T, const N: usize> Clone for Vec<T, N> where
T: Clone,
[src]fn clone(&self) -> Self
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pub fn clone_from(&mut self, source: &Self)
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impl<'a, T, const N: usize> Extend<&'a T> for Vec<T, N> where
T: 'a + Copy,
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impl<'a, T, const N: usize> Extend<&'a T> for Vec<T, N> where
T: 'a + Copy,
[src]fn extend<I>(&mut self, iter: I) where
I: IntoIterator<Item = &'a T>,
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I: IntoIterator<Item = &'a T>,
pub fn extend_one(&mut self, item: A)
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pub fn extend_reserve(&mut self, additional: usize)
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impl<T, const N: usize> Extend<T> for Vec<T, N>
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impl<T, const N: usize> Extend<T> for Vec<T, N>
[src]fn extend<I>(&mut self, iter: I) where
I: IntoIterator<Item = T>,
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I: IntoIterator<Item = T>,
pub fn extend_one(&mut self, item: A)
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pub fn extend_reserve(&mut self, additional: usize)
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impl<T, const N: usize> FromIterator<T> for Vec<T, N>
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impl<T, const N: usize> FromIterator<T> for Vec<T, N>
[src]fn from_iter<I>(iter: I) -> Self where
I: IntoIterator<Item = T>,
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I: IntoIterator<Item = T>,
impl<'a, T, const N: usize> IntoIterator for &'a Vec<T, N>
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impl<'a, T, const N: usize> IntoIterator for &'a Vec<T, N>
[src]impl<'a, T, const N: usize> IntoIterator for &'a mut Vec<T, N>
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impl<'a, T, const N: usize> IntoIterator for &'a mut Vec<T, N>
[src]impl<T, const N: usize> IntoIterator for Vec<T, N>
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impl<T, const N: usize> IntoIterator for Vec<T, N>
[src]impl<A, B, const N: usize, const M: usize> PartialEq<&'_ [B; M]> for Vec<A, N> where
A: PartialEq<B>,
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impl<A, B, const N: usize, const M: usize> PartialEq<&'_ [B; M]> for Vec<A, N> where
A: PartialEq<B>,
[src]impl<A, B, const N: usize, const M: usize> PartialEq<[B; M]> for Vec<A, N> where
A: PartialEq<B>,
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impl<A, B, const N: usize, const M: usize> PartialEq<[B; M]> for Vec<A, N> where
A: PartialEq<B>,
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