Struct memmap2::Mmap[][src]

pub struct Mmap { /* fields omitted */ }
Expand description

A handle to an immutable memory mapped buffer.

A Mmap may be backed by a file, or it can be anonymous map, backed by volatile memory. Use MmapOptions or map() to create a file-backed memory map. To create an immutable anonymous memory map, first create a mutable anonymous memory map, and then make it immutable with MmapMut::make_read_only().

A file backed Mmap is created by &File reference, and will remain valid even after the File is dropped. In other words, the Mmap handle is completely independent of the File used to create it. For consistency, on some platforms this is achieved by duplicating the underlying file handle. The memory will be unmapped when the Mmap handle is dropped.

Dereferencing and accessing the bytes of the buffer may result in page faults (e.g. swapping the mapped pages into physical memory) though the details of this are platform specific.

Mmap is Sync and Send.

Safety

All file-backed memory map constructors are marked unsafe because of the potential for Undefined Behavior (UB) using the map if the underlying file is subsequently modified, in or out of process. Applications must consider the risk and take appropriate precautions when using file-backed maps. Solutions such as file permissions, locks or process-private (e.g. unlinked) files exist but are platform specific and limited.

Example

use memmap2::MmapOptions;
use std::io::Write;
use std::fs::File;

let file = File::open("README.md")?;
let mmap = unsafe { MmapOptions::new().map(&file)? };
assert_eq!(b"# memmap2", &mmap[0..9]);

See MmapMut for the mutable version.

Implementations

impl Mmap[src]

pub unsafe fn map(file: &File) -> Result<Mmap>[src]

Creates a read-only memory map backed by a file.

This is equivalent to calling MmapOptions::new().map(file).

Errors

This method returns an error when the underlying system call fails, which can happen for a variety of reasons, such as when the file is not open with read permissions.

Example

use std::fs::File;
use std::io::Read;

use memmap2::Mmap;

let mut file = File::open("LICENSE-APACHE")?;

let mut contents = Vec::new();
file.read_to_end(&mut contents)?;

let mmap = unsafe { Mmap::map(&file)?  };

assert_eq!(&contents[..], &mmap[..]);

pub fn make_mut(self) -> Result<MmapMut>[src]

Transition the memory map to be writable.

If the memory map is file-backed, the file must have been opened with write permissions.

Errors

This method returns an error when the underlying system call fails, which can happen for a variety of reasons, such as when the file is not open with writable permissions.

Example

use memmap2::Mmap;
use std::ops::DerefMut;
use std::io::Write;

let file = /* file opened with write permissions */
let mmap = unsafe { Mmap::map(&file)? };
// ... use the read-only memory map ...
let mut mut_mmap = mmap.make_mut()?;
mut_mmap.deref_mut().write_all(b"hello, world!")?;

Methods from Deref<Target = [u8]>

pub const fn len(&self) -> usize1.0.0 (const: 1.39.0)[src]

Returns the number of elements in the slice.

Examples

let a = [1, 2, 3];
assert_eq!(a.len(), 3);

pub const fn is_empty(&self) -> bool1.0.0 (const: 1.39.0)[src]

Returns true if the slice has a length of 0.

Examples

let a = [1, 2, 3];
assert!(!a.is_empty());

pub const fn first(&self) -> Option<&T>1.0.0[src]

Returns the first element of the slice, or None if it is empty.

Examples

let v = [10, 40, 30];
assert_eq!(Some(&10), v.first());

let w: &[i32] = &[];
assert_eq!(None, w.first());

pub const fn split_first(&self) -> Option<(&T, &[T])>1.5.0[src]

Returns the first and all the rest of the elements of the slice, or None if it is empty.

Examples

let x = &[0, 1, 2];

if let Some((first, elements)) = x.split_first() {
    assert_eq!(first, &0);
    assert_eq!(elements, &[1, 2]);
}

pub const fn split_last(&self) -> Option<(&T, &[T])>1.5.0[src]

Returns the last and all the rest of the elements of the slice, or None if it is empty.

Examples

let x = &[0, 1, 2];

if let Some((last, elements)) = x.split_last() {
    assert_eq!(last, &2);
    assert_eq!(elements, &[0, 1]);
}

pub const fn last(&self) -> Option<&T>1.0.0[src]

Returns the last element of the slice, or None if it is empty.

Examples

let v = [10, 40, 30];
assert_eq!(Some(&30), v.last());

let w: &[i32] = &[];
assert_eq!(None, w.last());

pub fn get<I>(&self, index: I) -> Option<&<I as SliceIndex<[T]>>::Output> where
    I: SliceIndex<[T]>, 
1.0.0[src]

Returns a reference to an element or subslice depending on the type of index.

  • If given a position, returns a reference to the element at that position or None if out of bounds.
  • If given a range, returns the subslice corresponding to that range, or None if out of bounds.

Examples

let v = [10, 40, 30];
assert_eq!(Some(&40), v.get(1));
assert_eq!(Some(&[10, 40][..]), v.get(0..2));
assert_eq!(None, v.get(3));
assert_eq!(None, v.get(0..4));

pub unsafe fn get_unchecked<I>(
    &self,
    index: I
) -> &<I as SliceIndex<[T]>>::Output where
    I: SliceIndex<[T]>, 
1.0.0[src]

Returns a reference to an element or subslice, without doing bounds checking.

For a safe alternative see get.

Safety

Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used.

Examples

let x = &[1, 2, 4];

unsafe {
    assert_eq!(x.get_unchecked(1), &2);
}

pub const fn as_ptr(&self) -> *const T1.0.0 (const: 1.32.0)[src]

Returns a raw pointer to the slice’s buffer.

The caller must ensure that the slice outlives the pointer this function returns, or else it will end up pointing to garbage.

The caller must also ensure that the memory the pointer (non-transitively) points to is never written to (except inside an UnsafeCell) using this pointer or any pointer derived from it. If you need to mutate the contents of the slice, use as_mut_ptr.

Modifying the container referenced by this slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.

Examples

let x = &[1, 2, 4];
let x_ptr = x.as_ptr();

unsafe {
    for i in 0..x.len() {
        assert_eq!(x.get_unchecked(i), &*x_ptr.add(i));
    }
}

pub const fn as_ptr_range(&self) -> Range<*const T>1.48.0[src]

Returns the two raw pointers spanning the slice.

The returned range is half-open, which means that the end pointer points one past the last element of the slice. This way, an empty slice is represented by two equal pointers, and the difference between the two pointers represents the size of the slice.

See as_ptr for warnings on using these pointers. The end pointer requires extra caution, as it does not point to a valid element in the slice.

This function is useful for interacting with foreign interfaces which use two pointers to refer to a range of elements in memory, as is common in C++.

It can also be useful to check if a pointer to an element refers to an element of this slice:

let a = [1, 2, 3];
let x = &a[1] as *const _;
let y = &5 as *const _;

assert!(a.as_ptr_range().contains(&x));
assert!(!a.as_ptr_range().contains(&y));

pub fn iter(&self) -> Iter<'_, T>1.0.0[src]

Returns an iterator over the slice.

Examples

let x = &[1, 2, 4];
let mut iterator = x.iter();

assert_eq!(iterator.next(), Some(&1));
assert_eq!(iterator.next(), Some(&2));
assert_eq!(iterator.next(), Some(&4));
assert_eq!(iterator.next(), None);

pub fn windows(&self, size: usize) -> Windows<'_, T>1.0.0[src]

Returns an iterator over all contiguous windows of length size. The windows overlap. If the slice is shorter than size, the iterator returns no values.

Panics

Panics if size is 0.

Examples

let slice = ['r', 'u', 's', 't'];
let mut iter = slice.windows(2);
assert_eq!(iter.next().unwrap(), &['r', 'u']);
assert_eq!(iter.next().unwrap(), &['u', 's']);
assert_eq!(iter.next().unwrap(), &['s', 't']);
assert!(iter.next().is_none());

If the slice is shorter than size:

let slice = ['f', 'o', 'o'];
let mut iter = slice.windows(4);
assert!(iter.next().is_none());

pub fn chunks(&self, chunk_size: usize) -> Chunks<'_, T>1.0.0[src]

Returns an iterator over chunk_size elements of the slice at a time, starting at the beginning of the slice.

The chunks are slices and do not overlap. If chunk_size does not divide the length of the slice, then the last chunk will not have length chunk_size.

See chunks_exact for a variant of this iterator that returns chunks of always exactly chunk_size elements, and rchunks for the same iterator but starting at the end of the slice.

Panics

Panics if chunk_size is 0.

Examples

let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.chunks(2);
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert_eq!(iter.next().unwrap(), &['m']);
assert!(iter.next().is_none());

pub fn chunks_exact(&self, chunk_size: usize) -> ChunksExact<'_, T>1.31.0[src]

Returns an iterator over chunk_size elements of the slice at a time, starting at the beginning of the slice.

The chunks are slices and do not overlap. If chunk_size does not divide the length of the slice, then the last up to chunk_size-1 elements will be omitted and can be retrieved from the remainder function of the iterator.

Due to each chunk having exactly chunk_size elements, the compiler can often optimize the resulting code better than in the case of chunks.

See chunks for a variant of this iterator that also returns the remainder as a smaller chunk, and rchunks_exact for the same iterator but starting at the end of the slice.

Panics

Panics if chunk_size is 0.

Examples

let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.chunks_exact(2);
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['m']);

pub unsafe fn as_chunks_unchecked<const N: usize>(&self) -> &[[T; N]]

Notable traits for &'_ [u8]

impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
[src]

🔬 This is a nightly-only experimental API. (slice_as_chunks)

Splits the slice into a slice of N-element arrays, assuming that there’s no remainder.

Safety

This may only be called when

  • The slice splits exactly into N-element chunks (aka self.len() % N == 0).
  • N != 0.

Examples

#![feature(slice_as_chunks)]
let slice: &[char] = &['l', 'o', 'r', 'e', 'm', '!'];
let chunks: &[[char; 1]] =
    // SAFETY: 1-element chunks never have remainder
    unsafe { slice.as_chunks_unchecked() };
assert_eq!(chunks, &[['l'], ['o'], ['r'], ['e'], ['m'], ['!']]);
let chunks: &[[char; 3]] =
    // SAFETY: The slice length (6) is a multiple of 3
    unsafe { slice.as_chunks_unchecked() };
assert_eq!(chunks, &[['l', 'o', 'r'], ['e', 'm', '!']]);

// These would be unsound:
// let chunks: &[[_; 5]] = slice.as_chunks_unchecked() // The slice length is not a multiple of 5
// let chunks: &[[_; 0]] = slice.as_chunks_unchecked() // Zero-length chunks are never allowed

pub fn as_chunks<const N: usize>(&self) -> (&[[T; N]], &[T])[src]

🔬 This is a nightly-only experimental API. (slice_as_chunks)

Splits the slice into a slice of N-element arrays, starting at the beginning of the slice, and a remainder slice with length strictly less than N.

Panics

Panics if N is 0. This check will most probably get changed to a compile time error before this method gets stabilized.

Examples

#![feature(slice_as_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let (chunks, remainder) = slice.as_chunks();
assert_eq!(chunks, &[['l', 'o'], ['r', 'e']]);
assert_eq!(remainder, &['m']);

pub fn as_rchunks<const N: usize>(&self) -> (&[T], &[[T; N]])[src]

🔬 This is a nightly-only experimental API. (slice_as_chunks)

Splits the slice into a slice of N-element arrays, starting at the end of the slice, and a remainder slice with length strictly less than N.

Panics

Panics if N is 0. This check will most probably get changed to a compile time error before this method gets stabilized.

Examples

#![feature(slice_as_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let (remainder, chunks) = slice.as_rchunks();
assert_eq!(remainder, &['l']);
assert_eq!(chunks, &[['o', 'r'], ['e', 'm']]);

pub fn array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N>[src]

🔬 This is a nightly-only experimental API. (array_chunks)

Returns an iterator over N elements of the slice at a time, starting at the beginning of the slice.

The chunks are array references and do not overlap. If N does not divide the length of the slice, then the last up to N-1 elements will be omitted and can be retrieved from the remainder function of the iterator.

This method is the const generic equivalent of chunks_exact.

Panics

Panics if N is 0. This check will most probably get changed to a compile time error before this method gets stabilized.

Examples

#![feature(array_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.array_chunks();
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['m']);

pub fn array_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N>[src]

🔬 This is a nightly-only experimental API. (array_windows)

Returns an iterator over overlapping windows of N elements of a slice, starting at the beginning of the slice.

This is the const generic equivalent of windows.

If N is greater than the size of the slice, it will return no windows.

Panics

Panics if N is 0. This check will most probably get changed to a compile time error before this method gets stabilized.

Examples

#![feature(array_windows)]
let slice = [0, 1, 2, 3];
let mut iter = slice.array_windows();
assert_eq!(iter.next().unwrap(), &[0, 1]);
assert_eq!(iter.next().unwrap(), &[1, 2]);
assert_eq!(iter.next().unwrap(), &[2, 3]);
assert!(iter.next().is_none());

pub fn rchunks(&self, chunk_size: usize) -> RChunks<'_, T>1.31.0[src]

Returns an iterator over chunk_size elements of the slice at a time, starting at the end of the slice.

The chunks are slices and do not overlap. If chunk_size does not divide the length of the slice, then the last chunk will not have length chunk_size.

See rchunks_exact for a variant of this iterator that returns chunks of always exactly chunk_size elements, and chunks for the same iterator but starting at the beginning of the slice.

Panics

Panics if chunk_size is 0.

Examples

let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert_eq!(iter.next().unwrap(), &['l']);
assert!(iter.next().is_none());

pub fn rchunks_exact(&self, chunk_size: usize) -> RChunksExact<'_, T>1.31.0[src]

Returns an iterator over chunk_size elements of the slice at a time, starting at the end of the slice.

The chunks are slices and do not overlap. If chunk_size does not divide the length of the slice, then the last up to chunk_size-1 elements will be omitted and can be retrieved from the remainder function of the iterator.

Due to each chunk having exactly chunk_size elements, the compiler can often optimize the resulting code better than in the case of chunks.

See rchunks for a variant of this iterator that also returns the remainder as a smaller chunk, and chunks_exact for the same iterator but starting at the beginning of the slice.

Panics

Panics if chunk_size is 0.

Examples

let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks_exact(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['l']);

pub fn group_by<F>(&self, pred: F) -> GroupBy<'_, T, F> where
    F: FnMut(&T, &T) -> bool
[src]

🔬 This is a nightly-only experimental API. (slice_group_by)

Returns an iterator over the slice producing non-overlapping runs of elements using the predicate to separate them.

The predicate is called on two elements following themselves, it means the predicate is called on slice[0] and slice[1] then on slice[1] and slice[2] and so on.

Examples

#![feature(slice_group_by)]

let slice = &[1, 1, 1, 3, 3, 2, 2, 2];

let mut iter = slice.group_by(|a, b| a == b);

assert_eq!(iter.next(), Some(&[1, 1, 1][..]));
assert_eq!(iter.next(), Some(&[3, 3][..]));
assert_eq!(iter.next(), Some(&[2, 2, 2][..]));
assert_eq!(iter.next(), None);

This method can be used to extract the sorted subslices:

#![feature(slice_group_by)]

let slice = &[1, 1, 2, 3, 2, 3, 2, 3, 4];

let mut iter = slice.group_by(|a, b| a <= b);

assert_eq!(iter.next(), Some(&[1, 1, 2, 3][..]));
assert_eq!(iter.next(), Some(&[2, 3][..]));
assert_eq!(iter.next(), Some(&[2, 3, 4][..]));
assert_eq!(iter.next(), None);

pub fn split_at(&self, mid: usize) -> (&[T], &[T])1.0.0[src]

Divides one slice into two at an index.

The first will contain all indices from [0, mid) (excluding the index mid itself) and the second will contain all indices from [mid, len) (excluding the index len itself).

Panics

Panics if mid > len.

Examples

let v = [1, 2, 3, 4, 5, 6];

{
   let (left, right) = v.split_at(0);
   assert_eq!(left, []);
   assert_eq!(right, [1, 2, 3, 4, 5, 6]);
}

{
    let (left, right) = v.split_at(2);
    assert_eq!(left, [1, 2]);
    assert_eq!(right, [3, 4, 5, 6]);
}

{
    let (left, right) = v.split_at(6);
    assert_eq!(left, [1, 2, 3, 4, 5, 6]);
    assert_eq!(right, []);
}

pub fn split<F>(&self, pred: F) -> Split<'_, T, F> where
    F: FnMut(&T) -> bool
1.0.0[src]

Returns an iterator over subslices separated by elements that match pred. The matched element is not contained in the subslices.

Examples

let slice = [10, 40, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());

If the first element is matched, an empty slice will be the first item returned by the iterator. Similarly, if the last element in the slice is matched, an empty slice will be the last item returned by the iterator:

let slice = [10, 40, 33];
let mut iter = slice.split(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &[]);
assert!(iter.next().is_none());

If two matched elements are directly adjacent, an empty slice will be present between them:

let slice = [10, 6, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[10]);
assert_eq!(iter.next().unwrap(), &[]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());

pub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F> where
    F: FnMut(&T) -> bool
1.51.0[src]

Returns an iterator over subslices separated by elements that match pred. The matched element is contained in the end of the previous subslice as a terminator.

Examples

let slice = [10, 40, 33, 20];
let mut iter = slice.split_inclusive(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[10, 40, 33]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());

If the last element of the slice is matched, that element will be considered the terminator of the preceding slice. That slice will be the last item returned by the iterator.

let slice = [3, 10, 40, 33];
let mut iter = slice.split_inclusive(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[3]);
assert_eq!(iter.next().unwrap(), &[10, 40, 33]);
assert!(iter.next().is_none());

pub fn rsplit<F>(&self, pred: F) -> RSplit<'_, T, F> where
    F: FnMut(&T) -> bool
1.27.0[src]

Returns an iterator over subslices separated by elements that match pred, starting at the end of the slice and working backwards. The matched element is not contained in the subslices.

Examples

let slice = [11, 22, 33, 0, 44, 55];
let mut iter = slice.rsplit(|num| *num == 0);

assert_eq!(iter.next().unwrap(), &[44, 55]);
assert_eq!(iter.next().unwrap(), &[11, 22, 33]);
assert_eq!(iter.next(), None);

As with split(), if the first or last element is matched, an empty slice will be the first (or last) item returned by the iterator.

let v = &[0, 1, 1, 2, 3, 5, 8];
let mut it = v.rsplit(|n| *n % 2 == 0);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next().unwrap(), &[3, 5]);
assert_eq!(it.next().unwrap(), &[1, 1]);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next(), None);

pub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<'_, T, F> where
    F: FnMut(&T) -> bool
1.0.0[src]

Returns an iterator over subslices separated by elements that match pred, limited to returning at most n items. The matched element is not contained in the subslices.

The last element returned, if any, will contain the remainder of the slice.

Examples

Print the slice split once by numbers divisible by 3 (i.e., [10, 40], [20, 60, 50]):

let v = [10, 40, 30, 20, 60, 50];

for group in v.splitn(2, |num| *num % 3 == 0) {
    println!("{:?}", group);
}

pub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<'_, T, F> where
    F: FnMut(&T) -> bool
1.0.0[src]

Returns an iterator over subslices separated by elements that match pred limited to returning at most n items. This starts at the end of the slice and works backwards. The matched element is not contained in the subslices.

The last element returned, if any, will contain the remainder of the slice.

Examples

Print the slice split once, starting from the end, by numbers divisible by 3 (i.e., [50], [10, 40, 30, 20]):

let v = [10, 40, 30, 20, 60, 50];

for group in v.rsplitn(2, |num| *num % 3 == 0) {
    println!("{:?}", group);
}

pub fn contains(&self, x: &T) -> bool where
    T: PartialEq<T>, 
1.0.0[src]

Returns true if the slice contains an element with the given value.

Examples

let v = [10, 40, 30];
assert!(v.contains(&30));
assert!(!v.contains(&50));

If you do not have a &T, but some other value that you can compare with one (for example, String implements PartialEq<str>), you can use iter().any:

let v = [String::from("hello"), String::from("world")]; // slice of `String`
assert!(v.iter().any(|e| e == "hello")); // search with `&str`
assert!(!v.iter().any(|e| e == "hi"));

pub fn starts_with(&self, needle: &[T]) -> bool where
    T: PartialEq<T>, 
1.0.0[src]

Returns true if needle is a prefix of the slice.

Examples

let v = [10, 40, 30];
assert!(v.starts_with(&[10]));
assert!(v.starts_with(&[10, 40]));
assert!(!v.starts_with(&[50]));
assert!(!v.starts_with(&[10, 50]));

Always returns true if needle is an empty slice:

let v = &[10, 40, 30];
assert!(v.starts_with(&[]));
let v: &[u8] = &[];
assert!(v.starts_with(&[]));

pub fn ends_with(&self, needle: &[T]) -> bool where
    T: PartialEq<T>, 
1.0.0[src]

Returns true if needle is a suffix of the slice.

Examples

let v = [10, 40, 30];
assert!(v.ends_with(&[30]));
assert!(v.ends_with(&[40, 30]));
assert!(!v.ends_with(&[50]));
assert!(!v.ends_with(&[50, 30]));

Always returns true if needle is an empty slice:

let v = &[10, 40, 30];
assert!(v.ends_with(&[]));
let v: &[u8] = &[];
assert!(v.ends_with(&[]));

#[must_use = "returns the subslice without modifying the original"]
pub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]> where
    T: PartialEq<T>,
    P: SlicePattern<Item = T> + ?Sized
1.51.0[src]

Returns a subslice with the prefix removed.

If the slice starts with prefix, returns the subslice after the prefix, wrapped in Some. If prefix is empty, simply returns the original slice.

If the slice does not start with prefix, returns None.

Examples

let v = &[10, 40, 30];
assert_eq!(v.strip_prefix(&[10]), Some(&[40, 30][..]));
assert_eq!(v.strip_prefix(&[10, 40]), Some(&[30][..]));
assert_eq!(v.strip_prefix(&[50]), None);
assert_eq!(v.strip_prefix(&[10, 50]), None);

let prefix : &str = "he";
assert_eq!(b"hello".strip_prefix(prefix.as_bytes()),
           Some(b"llo".as_ref()));

#[must_use = "returns the subslice without modifying the original"]
pub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]> where
    T: PartialEq<T>,
    P: SlicePattern<Item = T> + ?Sized
1.51.0[src]

Returns a subslice with the suffix removed.

If the slice ends with suffix, returns the subslice before the suffix, wrapped in Some. If suffix is empty, simply returns the original slice.

If the slice does not end with suffix, returns None.

Examples

let v = &[10, 40, 30];
assert_eq!(v.strip_suffix(&[30]), Some(&[10, 40][..]));
assert_eq!(v.strip_suffix(&[40, 30]), Some(&[10][..]));
assert_eq!(v.strip_suffix(&[50]), None);
assert_eq!(v.strip_suffix(&[50, 30]), None);

Binary searches this sorted slice for a given element.

If the value is found then Result::Ok is returned, containing the index of the matching element. If there are multiple matches, then any one of the matches could be returned. If the value is not found then Result::Err is returned, containing the index where a matching element could be inserted while maintaining sorted order.

See also binary_search_by, binary_search_by_key, and partition_point.

Examples

Looks up a series of four elements. The first is found, with a uniquely determined position; the second and third are not found; the fourth could match any position in [1, 4].

let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];

assert_eq!(s.binary_search(&13),  Ok(9));
assert_eq!(s.binary_search(&4),   Err(7));
assert_eq!(s.binary_search(&100), Err(13));
let r = s.binary_search(&1);
assert!(match r { Ok(1..=4) => true, _ => false, });

If you want to insert an item to a sorted vector, while maintaining sort order:

let mut s = vec![0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let num = 42;
let idx = s.binary_search(&num).unwrap_or_else(|x| x);
s.insert(idx, num);
assert_eq!(s, [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 42, 55]);

pub fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize> where
    F: FnMut(&'a T) -> Ordering
1.0.0[src]

Binary searches this sorted slice with a comparator function.

The comparator function should implement an order consistent with the sort order of the underlying slice, returning an order code that indicates whether its argument is Less, Equal or Greater the desired target.

If the value is found then Result::Ok is returned, containing the index of the matching element. If there are multiple matches, then any one of the matches could be returned. If the value is not found then Result::Err is returned, containing the index where a matching element could be inserted while maintaining sorted order.

See also binary_search, binary_search_by_key, and partition_point.

Examples

Looks up a series of four elements. The first is found, with a uniquely determined position; the second and third are not found; the fourth could match any position in [1, 4].

let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];

let seek = 13;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Ok(9));
let seek = 4;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(7));
let seek = 100;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(13));
let seek = 1;
let r = s.binary_search_by(|probe| probe.cmp(&seek));
assert!(match r { Ok(1..=4) => true, _ => false, });

pub fn binary_search_by_key<'a, B, F>(
    &'a self,
    b: &B,
    f: F
) -> Result<usize, usize> where
    F: FnMut(&'a T) -> B,
    B: Ord
1.10.0[src]

Binary searches this sorted slice with a key extraction function.

Assumes that the slice is sorted by the key, for instance with sort_by_key using the same key extraction function.

If the value is found then Result::Ok is returned, containing the index of the matching element. If there are multiple matches, then any one of the matches could be returned. If the value is not found then Result::Err is returned, containing the index where a matching element could be inserted while maintaining sorted order.

See also binary_search, binary_search_by, and partition_point.

Examples

Looks up a series of four elements in a slice of pairs sorted by their second elements. The first is found, with a uniquely determined position; the second and third are not found; the fourth could match any position in [1, 4].

let s = [(0, 0), (2, 1), (4, 1), (5, 1), (3, 1),
         (1, 2), (2, 3), (4, 5), (5, 8), (3, 13),
         (1, 21), (2, 34), (4, 55)];

assert_eq!(s.binary_search_by_key(&13, |&(a, b)| b),  Ok(9));
assert_eq!(s.binary_search_by_key(&4, |&(a, b)| b),   Err(7));
assert_eq!(s.binary_search_by_key(&100, |&(a, b)| b), Err(13));
let r = s.binary_search_by_key(&1, |&(a, b)| b);
assert!(match r { Ok(1..=4) => true, _ => false, });

pub unsafe fn align_to<U>(&self) -> (&[T], &[U], &[T])1.30.0[src]

Transmute the slice to a slice of another type, ensuring alignment of the types is maintained.

This method splits the slice into three distinct slices: prefix, correctly aligned middle slice of a new type, and the suffix slice. The method may make the middle slice the greatest length possible for a given type and input slice, but only your algorithm’s performance should depend on that, not its correctness. It is permissible for all of the input data to be returned as the prefix or suffix slice.

This method has no purpose when either input element T or output element U are zero-sized and will return the original slice without splitting anything.

Safety

This method is essentially a transmute with respect to the elements in the returned middle slice, so all the usual caveats pertaining to transmute::<T, U> also apply here.

Examples

Basic usage:

unsafe {
    let bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
    let (prefix, shorts, suffix) = bytes.align_to::<u16>();
    // less_efficient_algorithm_for_bytes(prefix);
    // more_efficient_algorithm_for_aligned_shorts(shorts);
    // less_efficient_algorithm_for_bytes(suffix);
}

pub fn is_sorted(&self) -> bool where
    T: PartialOrd<T>, 
[src]

🔬 This is a nightly-only experimental API. (is_sorted)

new API

Checks if the elements of this slice are sorted.

That is, for each element a and its following element b, a <= b must hold. If the slice yields exactly zero or one element, true is returned.

Note that if Self::Item is only PartialOrd, but not Ord, the above definition implies that this function returns false if any two consecutive items are not comparable.

Examples

#![feature(is_sorted)]
let empty: [i32; 0] = [];

assert!([1, 2, 2, 9].is_sorted());
assert!(![1, 3, 2, 4].is_sorted());
assert!([0].is_sorted());
assert!(empty.is_sorted());
assert!(![0.0, 1.0, f32::NAN].is_sorted());

pub fn is_sorted_by<F>(&self, compare: F) -> bool where
    F: FnMut(&T, &T) -> Option<Ordering>, 
[src]

🔬 This is a nightly-only experimental API. (is_sorted)

new API

Checks if the elements of this slice are sorted using the given comparator function.

Instead of using PartialOrd::partial_cmp, this function uses the given compare function to determine the ordering of two elements. Apart from that, it’s equivalent to is_sorted; see its documentation for more information.

pub fn is_sorted_by_key<F, K>(&self, f: F) -> bool where
    K: PartialOrd<K>,
    F: FnMut(&T) -> K, 
[src]

🔬 This is a nightly-only experimental API. (is_sorted)

new API

Checks if the elements of this slice are sorted using the given key extraction function.

Instead of comparing the slice’s elements directly, this function compares the keys of the elements, as determined by f. Apart from that, it’s equivalent to is_sorted; see its documentation for more information.

Examples

#![feature(is_sorted)]

assert!(["c", "bb", "aaa"].is_sorted_by_key(|s| s.len()));
assert!(![-2i32, -1, 0, 3].is_sorted_by_key(|n| n.abs()));

pub fn partition_point<P>(&self, pred: P) -> usize where
    P: FnMut(&T) -> bool
1.52.0[src]

Returns the index of the partition point according to the given predicate (the index of the first element of the second partition).

The slice is assumed to be partitioned according to the given predicate. This means that all elements for which the predicate returns true are at the start of the slice and all elements for which the predicate returns false are at the end. For example, [7, 15, 3, 5, 4, 12, 6] is a partitioned under the predicate x % 2 != 0 (all odd numbers are at the start, all even at the end).

If this slice is not partitioned, the returned result is unspecified and meaningless, as this method performs a kind of binary search.

See also binary_search, binary_search_by, and binary_search_by_key.

Examples

let v = [1, 2, 3, 3, 5, 6, 7];
let i = v.partition_point(|&x| x < 5);

assert_eq!(i, 4);
assert!(v[..i].iter().all(|&x| x < 5));
assert!(v[i..].iter().all(|&x| !(x < 5)));

pub fn is_ascii(&self) -> bool1.23.0[src]

Checks if all bytes in this slice are within the ASCII range.

pub fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool1.23.0[src]

Checks that two slices are an ASCII case-insensitive match.

Same as to_ascii_lowercase(a) == to_ascii_lowercase(b), but without allocating and copying temporaries.

pub fn escape_ascii(&self) -> EscapeAscii<'_>[src]

🔬 This is a nightly-only experimental API. (inherent_ascii_escape)

Returns an iterator that produces an escaped version of this slice, treating it as an ASCII string.

Examples

#![feature(inherent_ascii_escape)]

let s = b"0\t\r\n'\"\\\x9d";
let escaped = s.escape_ascii().to_string();
assert_eq!(escaped, "0\\t\\r\\n\\'\\\"\\\\\\x9d");

pub fn to_vec(&self) -> Vec<T, Global> where
    T: Clone
1.0.0[src]

Copies self into a new Vec.

Examples

let s = [10, 40, 30];
let x = s.to_vec();
// Here, `s` and `x` can be modified independently.

pub fn to_vec_in<A>(&self, alloc: A) -> Vec<T, A> where
    T: Clone,
    A: Allocator
[src]

🔬 This is a nightly-only experimental API. (allocator_api)

Copies self into a new Vec with an allocator.

Examples

#![feature(allocator_api)]

use std::alloc::System;

let s = [10, 40, 30];
let x = s.to_vec_in(System);
// Here, `s` and `x` can be modified independently.

pub fn repeat(&self, n: usize) -> Vec<T, Global> where
    T: Copy
1.40.0[src]

Creates a vector by repeating a slice n times.

Panics

This function will panic if the capacity would overflow.

Examples

Basic usage:

assert_eq!([1, 2].repeat(3), vec![1, 2, 1, 2, 1, 2]);

A panic upon overflow:

// this will panic at runtime
b"0123456789abcdef".repeat(usize::MAX);

pub fn concat<Item>(&self) -> <[T] as Concat<Item>>::Output

Notable traits for &'_ [u8]

impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
where
    Item: ?Sized,
    [T]: Concat<Item>, 
1.0.0[src]

Flattens a slice of T into a single value Self::Output.

Examples

assert_eq!(["hello", "world"].concat(), "helloworld");
assert_eq!([[1, 2], [3, 4]].concat(), [1, 2, 3, 4]);

pub fn join<Separator>(
    &self,
    sep: Separator
) -> <[T] as Join<Separator>>::Output

Notable traits for &'_ [u8]

impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
where
    [T]: Join<Separator>, 
1.3.0[src]

Flattens a slice of T into a single value Self::Output, placing a given separator between each.

Examples

assert_eq!(["hello", "world"].join(" "), "hello world");
assert_eq!([[1, 2], [3, 4]].join(&0), [1, 2, 0, 3, 4]);
assert_eq!([[1, 2], [3, 4]].join(&[0, 0][..]), [1, 2, 0, 0, 3, 4]);

pub fn connect<Separator>(
    &self,
    sep: Separator
) -> <[T] as Join<Separator>>::Output

Notable traits for &'_ [u8]

impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
where
    [T]: Join<Separator>, 
1.0.0[src]

👎 Deprecated since 1.3.0:

renamed to join

Flattens a slice of T into a single value Self::Output, placing a given separator between each.

Examples

assert_eq!(["hello", "world"].connect(" "), "hello world");
assert_eq!([[1, 2], [3, 4]].connect(&0), [1, 2, 0, 3, 4]);

pub fn to_ascii_uppercase(&self) -> Vec<u8, Global>1.23.0[src]

Returns a vector containing a copy of this slice where each byte is mapped to its ASCII upper case equivalent.

ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.

To uppercase the value in-place, use make_ascii_uppercase.

pub fn to_ascii_lowercase(&self) -> Vec<u8, Global>1.23.0[src]

Returns a vector containing a copy of this slice where each byte is mapped to its ASCII lower case equivalent.

ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.

To lowercase the value in-place, use make_ascii_lowercase.

Trait Implementations

impl AsRef<[u8]> for Mmap[src]

fn as_ref(&self) -> &[u8]

Notable traits for &'_ [u8]

impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
[src]

Performs the conversion.

impl Debug for Mmap[src]

fn fmt(&self, fmt: &mut Formatter<'_>) -> Result[src]

Formats the value using the given formatter. Read more

impl Deref for Mmap[src]

type Target = [u8]

The resulting type after dereferencing.

fn deref(&self) -> &[u8]

Notable traits for &'_ [u8]

impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
[src]

Dereferences the value.

Auto Trait Implementations

impl RefUnwindSafe for Mmap

impl Send for Mmap

impl Sync for Mmap

impl Unpin for Mmap

impl UnwindSafe for Mmap

Blanket Implementations

impl<T> Any for T where
    T: 'static + ?Sized
[src]

pub fn type_id(&self) -> TypeId[src]

Gets the TypeId of self. Read more

impl<T> Borrow<T> for T where
    T: ?Sized
[src]

pub fn borrow(&self) -> &T[src]

Immutably borrows from an owned value. Read more

impl<T> BorrowMut<T> for T where
    T: ?Sized
[src]

pub fn borrow_mut(&mut self) -> &mut T[src]

Mutably borrows from an owned value. Read more

impl<T> From<T> for T[src]

pub fn from(t: T) -> T[src]

Performs the conversion.

impl<T, U> Into<U> for T where
    U: From<T>, 
[src]

pub fn into(self) -> U[src]

Performs the conversion.

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 
[src]

type Error = Infallible

The type returned in the event of a conversion error.

pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>[src]

Performs the conversion.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 
[src]

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>[src]

Performs the conversion.