Struct DirEntry 

pub struct DirEntry { /* private fields */ }

A struct representing a directory entry with minimal memory overhead.

This struct is designed for high-performance file system traversal and analysis. It holds metadata and a path to a file or directory, optimised for size and efficient access to its components.

The struct’s memory footprint is

• Path: 16 bytes, Box<CStr>, retaining compatibility for use in libc but converting to &[u8] trivially(as deref)
• File type: 1-byte enum representing the entry’s type (file, directory, etc.).
• Inode: 8-byte integer for the file’s unique inode number.
• Depth: 4-byte integer indicating the entry’s depth from the root.
• File name index: 8-byte integer pointing to the start of the file name within the path buffer.
• is traversible cache: 1 byte Cell<Option<bool>> an Implementation detail that avoids recalling stat on symlinks

Examples

use fdf::fs::DirEntry;
use std::path::Path;
use std::fs::File;
use std::io::Write;
use std::sync::Arc;



// Create a temporary directory for the test
let temp_dir = std::env::temp_dir();


let file_path = temp_dir.join("test_file.txt");

// Create a file inside the temporary directory

let mut file = File::create(&file_path).expect("Failed to create file");
writeln!(file, "Hello, world!").expect("Failed to write to file");


// Create a DirEntry from the temporary file path
let entry = DirEntry::new(&file_path).unwrap();
assert!(entry.is_regular_file());
assert_eq!(entry.file_name(), b"test_file.txt");

Implementations

impl DirEntry

pub fn is_executable(&self) -> bool

Checks if the entry is an executable file.

This is a costly operation as it performs an access system call.

Examples

  use fdf::fs::DirEntry;
  use std::fs::{self, File};
  use std::os::unix::fs::PermissionsExt;
  use std::sync::Arc;

  let temp_dir = std::env::temp_dir();
  let exe_path = temp_dir.join("my_executable");
  File::create(&exe_path).unwrap().set_permissions(fs::Permissions::from_mode(0o755)).unwrap();

  let entry = DirEntry::new(&exe_path).unwrap();
  assert!(entry.is_executable());

  let non_exe_path = temp_dir.join("my_file");
  File::create(&non_exe_path).unwrap();
  let non_exe_entry = DirEntry::new(&non_exe_path).unwrap();
  assert!(!non_exe_entry.is_executable());
  fs::remove_file(exe_path).unwrap();
  fs::remove_file(non_exe_path).unwrap();

pub const fn as_ptr(&self) -> *const c_char

Returns a raw pointer to the underlying C string.

This provides access to the null-terminated C string representation of the file path for use with FFI functions.

pub const fn as_path(&self) -> &Path

Returns the underlying path as a Path

pub const fn as_os_str(&self) -> &OsStr

Returns the underlying path as an OsStr

pub const fn is_block_device(&self) -> bool

Cost free check for block devices

pub fn to_string_lossy(&self) -> Cow<'_, str>

pub const fn as_str(&self) -> Result<&str, Utf8Error>

Returns the underlying bytes as a UTF-8 string slice if valid.

Errors

Returns Err if the bytes are not valid UTF-8.

pub const fn is_char_device(&self) -> bool

Cost free check for character devices

pub const fn is_pipe(&self) -> bool

Cost free check for pipes (FIFOs)

pub const fn is_socket(&self) -> bool

Cost free check for sockets

pub const fn is_regular_file(&self) -> bool

Cost free check for regular files

pub const fn is_dir(&self) -> bool

Cost free check for directories

pub const fn is_unknown(&self) -> bool

Cost free check for unknown file types

pub const fn is_symlink(&self) -> bool

Cost free check for symlinks

pub fn is_empty(&self) -> bool

Checks if the entry is empty.

For files, it checks if the size is zero. For directories, it checks if there are no entries. This is a costly operation as it requires system calls (stat or getdents/readdir).

Examples

use fdf::fs::DirEntry;
use std::fs::{self, File};
use std::io::Write;
use std::sync::Arc;
let temp_dir = std::env::temp_dir();

// Check an empty file.
let empty_file_path = temp_dir.join("empty.txt");
File::create(&empty_file_path).unwrap();
let empty_entry = DirEntry::new(&empty_file_path).unwrap();
assert!(empty_entry.is_empty());

// Check a non-empty file.
let non_empty_file_path = temp_dir.join("not_empty.txt");
File::create(&non_empty_file_path).unwrap().write_all(b"Hello").unwrap();
let non_empty_entry = DirEntry::new(&non_empty_file_path).unwrap();
assert!(!non_empty_entry.is_empty());

// Check an empty directory.
let empty_dir_path = temp_dir.join("empty_dir");
fs::create_dir(&empty_dir_path).unwrap();
let empty_dir_entry = DirEntry::new(&empty_dir_path).unwrap();
assert!(empty_dir_entry.is_empty());

fs::remove_file(empty_file_path).unwrap();
fs::remove_file(non_empty_file_path).unwrap();
fs::remove_dir(empty_dir_path).unwrap();

pub const fn as_cstr(&self) -> &CStr

Returns the full path of this directory entry as a CStr.

This function provides direct access to the underlying null-terminated C string representing the entry’s absolute or relative path (depending on how it was created).

The returned reference is valid for the lifetime of the DirEntry and does not allocate.

Examples

use fdf::fs::DirEntry;
use std::fs::File;
use std::io::Write;
use std::os::unix::ffi::OsStrExt;
// Create a temporary file
let tmp = std::env::temp_dir().join("as_cstr_test.txt");
File::create(&tmp).unwrap().write_all(b"data").unwrap();

// Create a DirEntry from the file path
let entry = DirEntry::new(&tmp).unwrap();

// Retrieve full path as a CStr
let cstr = entry.as_cstr();

// It should match the full path string plus null terminator
let expected = std::ffi::CString::new(tmp.as_os_str().as_bytes()).unwrap();
assert_eq!(cstr.to_bytes_with_nul(), expected.to_bytes_with_nul());

// The CStr can be converted back to &str (if valid UTF-8)
let path_str = cstr.to_str().unwrap();
assert!(path_str.ends_with("as_cstr_test.txt"));
std::fs::remove_file(tmp).unwrap();

pub fn file_name_cstr(&self) -> &CStr

Returns the file name component of the entry as a CStr.

This slice is a view into the internal path buffer and includes the null terminator. It is guaranteed to be valid UTF-8 if and only if the file name is UTF-8.

Useful within the openat calls

Examples

use fdf::fs::DirEntry;
use std::fs::File;
use std::io::Write;

// Create a temporary file
let tmp = std::env::temp_dir().join("file_name_cstr_test.txt");
File::create(&tmp).unwrap().write_all(b"abc").unwrap();

// Build DirEntry
let entry = DirEntry::new(&tmp).unwrap();

// Extract file name as CStr
let cstr = entry.file_name_cstr();

// It should match the file name plus null terminator
assert_eq!(cstr.to_bytes_with_nul(), b"file_name_cstr_test.txt\0");

// We can also convert it to a &str
assert_eq!(cstr.to_str().unwrap(), "file_name_cstr_test.txt");

std::fs::remove_file(tmp).unwrap();

use fdf::fs::DirEntry;
use std::fs::File;

 // File name with spaces
let tmp = std::env::temp_dir().join("some name.txt");
File::create(&tmp).unwrap();



let entry = DirEntry::new(&tmp).unwrap();
let name = entry.file_name_cstr();

assert_eq!(name.to_str().unwrap(), "some name.txt");

std::fs::remove_file(tmp).unwrap();




let root_dir=DirEntry::new("/");

assert!(root_dir.is_err() || root_dir.is_ok_and(|x| x.file_name_cstr()==c"/"));

pub fn file_name(&self) -> &[u8]

Returns the name of the file (as bytes, no null terminator) ( Returns / or . when they are the entry)

use fdf::fs::DirEntry;
use std::fs::File;

// File name with spaces
let tmp = std::env::temp_dir().join("some name.txt");
File::create(&tmp).unwrap();



let entry = DirEntry::new(&tmp).unwrap();
let name = entry.file_name();

assert_eq!(name, b"some name.txt");

std::fs::remove_file(tmp).unwrap();




let root_dir=DirEntry::new("/");

assert!(root_dir.is_err() || root_dir.is_ok_and(|x| x.file_name()==b"/"));
// if on certain systems, root dir requires permissions, so we have to be careful (esp android)

let dot_dir=DirEntry::new(".");
assert!(dot_dir.is_ok_and(|x| x.file_name()==b"."));

pub fn to_inner(self) -> Box<CStr>

Takes the value of the path and gives the raw representation as a boxed Cstr

pub fn to_full_path(&self) -> Result<Self>

Converts a directory entry to a full, canonical path, resolving all symlinks

This is a costly operation as it involves a system call (realpath). If the filetype is a symlink, it invokes a stat call to find the realtype, otherwise stat is not called.

Errors

Returns an Err

It can be one of the following, FileType::AccessDenied, (EACCESS) FileType::TooManySymbolicLinks, ( ELOOP) FileType::InvalidPath (ENOENT) (There may be more, this documentation is not complete) TODO!

Examples

these tests are broken on macos because of funky stuff with mac’s privacy/security settings.

use fdf::fs::DirEntry;
use std::path::Path;
use std::fs;
use std::sync::Arc;
use std::os::unix::ffi::OsStrExt as _;
use std::os::unix::fs::symlink;
let temp_dir = std::env::temp_dir();
let target_path = temp_dir.join("target_file_full_path.txt");
fs::File::create(&target_path).unwrap();
let symlink_path = temp_dir.join("link_to_target_full_path.txt");
symlink(&target_path, &symlink_path).unwrap();

// Create a DirEntry from the symlink path
let entry = DirEntry::new(&symlink_path).unwrap();
assert!(entry.is_symlink());

// Canonicalise the path
let full_entry = entry.to_full_path().unwrap();

// The full path of the canonicalised entry should match the target path.
assert_eq!(full_entry.as_bytes(), target_path.as_os_str().as_bytes());

fs::remove_file(&symlink_path).unwrap();
fs::remove_file(&target_path).unwrap();

pub fn parent(&self) -> Option<&[u8]>

Returns the parent path as byte slice, or None if at root.

Examples

Basic usage with a temporary directory and file:

use fdf::fs::DirEntry;
use std::fs::File;
use std::os::unix::ffi::OsStrExt;
let tmp = std::env::temp_dir().join("fdf_parent_test_dir");
let _ = std::fs::remove_dir_all(&tmp);
std::fs::create_dir_all(&tmp).unwrap();
let file_path = tmp.join("file.txt");
File::create(&file_path).unwrap();

let entry = DirEntry::new(&file_path).unwrap();
assert_eq!(entry.parent().unwrap(), tmp.as_os_str().as_bytes());

std::fs::remove_file(&file_path).unwrap();
std::fs::remove_dir_all(&tmp).unwrap();

Root path yields None for parent (guarded to avoid failing on unusual systems): dot entries return an empty byte slice, mirroring semantics from stdlib.

use fdf::fs::DirEntry;

let root = DirEntry::new("/");
if let Ok(e) = root {
    assert!(e.parent().is_none());
}

let dot=DirEntry::new(".");
if let Ok(dotentry)=dot{
let parent=dotentry.parent();
assert!(dotentry.parent().is_some_and(|x| x.is_empty()));
}

pub fn is_readable(&self) -> bool

Checks if the file or directory is readable by the current process.

This uses the access system call with R_OK to check read permissions without actually opening the file. It follows symlinks.

Returns

true if the current process has read permission, false otherwise.

false if the file doesn’t exist or on permission errors.

pub fn is_writable(&self) -> bool

Checks if the file or directory is writable by the current process.

This uses the access system call with W_OK to check write permissions without actually opening the file. It follows symlinks.

Returns

true if the current process has write permission, false otherwise. false if the file doesn’t exist or on permission errors.

pub fn exists(&self) -> bool

Checks if the file exists.

This makes a system call to check file existence.

pub fn get_lstatat(&self, fd: &FileDes) -> Result<stat>

Gets file metadata using lstatat for a file relative to a directory file descriptor.

This function uses fstatat with AT_SYMLINK_NOFOLLOW to get metadata without following symbolic links, similar to lstat but relative to a directory fd.

Arguments

fd - Directory file descriptor to use as the base for relative path resolution

Returns

A stat structure containing file metadata on success.

Errors

Returns DirEntryError::IOError if the stat operation fails

pub fn get_lstat(&self) -> Result<stat>

Gets file status information without following symlinks.

This performs an lstat system call to retrieve metadata about the file, including type, permissions, size, and timestamps. Unlike stat, lstat returns information about the symlink itself rather than the target.

Errors

Returns an error if:

• The file doesn’t exist
• Permission is denied
• The path is invalid
• System call fails for any other reason

Returns DirEntryError::IOError if the stat operation fails

A stat structure containing file metadata on success.

pub fn get_stat(&self) -> Result<stat>

Gets file status information by following symlinks.

This performs a stat system call to retrieve metadata about the file, including type, permissions, size, and timestamps. Unlike lstat, stat follows symbolic links and returns information about the target file rather than the link itself.

Errors

Returns an error if:

• The file doesn’t exist
• Permission is denied
• The path is invalid
• A symlink target doesn’t exist
• System call fails for any other reason

Returns DirEntryError::IOError if the stat operation fails

A stat structure containing file metadata on success.

pub fn get_statat(&self, fd: &FileDes) -> Result<stat>

Gets file metadata using statat for a file relative to a directory file descriptor.

This function uses fstatat with AT_SYMLINK_FOLLOW to get metadata by following symbolic links, similar to stat but relative to a directory fd.

Arguments

fd - Directory file descriptor to use as the base for relative path resolution

Returns

A stat structure containing file metadata on success.

Errors

Returns DirEntryError::IOError if the stat operation fails

pub const fn as_bytes(&self) -> &[u8]

Cost free conversion to bytes (because it is already is bytes)

pub const fn len(&self) -> usize

Returns the length of the path string in bytes.

The length excludes the internal null terminator, so it matches what you’d expect from a regular Rust string slice length.

Examples

use fdf::fs::DirEntry;
use std::fs::File;

let tmp = std::env::temp_dir().join("test_file.txt");
File::create(&tmp).unwrap();

let entry = DirEntry::new(&tmp).unwrap();
// Length matches the path string without null terminator
assert_eq!(entry.len(), tmp.as_os_str().len());

std::fs::remove_file(tmp).unwrap();

pub const fn file_type(&self) -> FileType

Returns the file type of the file (eg directory, regular file, etc)

pub const fn depth(&self) -> usize

Returns the depth relative to the start directory, this is cost free

pub const fn ino(&self) -> u64

Returns the inode number of the file, cost free check

This is a unique identifier for the file on the filesystem, it is not the same as the file name or path, it is a number that identifies the file on the

pub fn filter<F: Fn(&Self) -> bool>(&self, func: F) -> bool

Applies a filter condition

pub const fn file_name_index(&self) -> usize

Returns the length of the base path (eg /home/user/ is 6 ‘/home/’) and ‘/’ is 0

pub fn is_traversible(&self) -> bool

Checks if the file is a directory or symlink (but internally a directory)

pub const fn is_hidden(&self) -> bool

Checks if the file is hidden (e.g., .gitignore, .config).

A file is considered hidden if its filename (not the full path) starts with a dot (‘.’) character.

Useful for filtering out hidden files in directory listings.

Examples

use fdf::fs::DirEntry;
use std::fs::File;
use std::io::Write;

// Create a temporary hidden file
let tmp = std::env::temp_dir().join(".hidden_file.txt");
File::create(&tmp).unwrap().write_all(b"content").unwrap();

// Build DirEntry
let entry = DirEntry::new(&tmp).unwrap();

// Check if it's hidden
assert!(entry.is_hidden());

std::fs::remove_file(tmp).unwrap();

use fdf::fs::DirEntry;
use std::fs::File;

// Regular non-hidden file
let tmp = std::env::temp_dir().join("visible_file.txt");
File::create(&tmp).unwrap();

let entry = DirEntry::new(&tmp).unwrap();
assert!(!entry.is_hidden());

std::fs::remove_file(tmp).unwrap();

use fdf::fs::DirEntry;
use std::fs::File;

// File with multiple dots but not hidden
let tmp = std::env::temp_dir().join("backup.old.txt");
File::create(&tmp).unwrap();

let entry = DirEntry::new(&tmp).unwrap();
assert!(!entry.is_hidden());

std::fs::remove_file(tmp).unwrap();

use fdf::fs::DirEntry;
use std::fs::File;

// Edge case: just a dot
let tmp = std::env::temp_dir().join(".helo");
File::create(&tmp).unwrap();

let entry = DirEntry::new(&tmp).unwrap();
assert!(entry.is_hidden());

std::fs::remove_file(tmp).unwrap();

pub fn dirname(&self) -> &[u8]

Returns the directory name of the file (as bytes)

use fdf::fs::DirEntry;
use std::fs::File;
use std::io::Write;

// Test 1: Regular file path with directory structure
let tmp = std::env::temp_dir().join("test_dir/file.txt");
if let Some(parent) = tmp.parent() {
   std::fs::create_dir_all(parent).unwrap();
   }
   File::create(&tmp).unwrap();

   let entry = DirEntry::new(&tmp).unwrap();
   assert_eq!(entry.dirname(), b"test_dir");

   std::fs::remove_file(&tmp).unwrap();
   std::fs::remove_dir_all(tmp.parent().unwrap()).unwrap();


   let root_dir=DirEntry::new("/");
   assert!(root_dir.is_err() || root_dir.is_ok_and(|x| x.dirname()==b"/"));

pub fn extension(&self) -> Option<&[u8]>

Extracts the extension of the file name, if any.

The extension is defined as the substring after the last dot (.) character in the file name, excluding cases where the dot is the final character.

Examples

use fdf::fs::DirEntry;
use std::env::temp_dir;

let tmp=std::env::temp_dir();
let file_test=tmp.join("file.txt");
 std::fs::File::create(&file_test).unwrap();

let path = DirEntry::new(&file_test).unwrap();
assert_eq!(path.extension(), Some(b"txt".as_ref()));
 std::fs::remove_file(&file_test).unwrap();

let root_dir=DirEntry::new("/");
assert!(root_dir.is_err() || root_dir.is_ok_and(|path| path.extension().is_none()));

pub fn new<T: AsRef<OsStr>>(path: T) -> Result<Self>

Creates a new DirEntry from the given path.

This constructor attempts to resolve metadata for the provided path using a lstat call. If successful, it initialises a DirEntry with the path, file type, inode, and some derived metadata such as depth and file name index.

Examples

use fdf::fs::DirEntry;
use std::env;

   // Use the system temporary directory
   let tmp = env::temp_dir();

   // Create a DirEntry from the temporary directory path
   let entry = DirEntry::new(tmp)?;

   println!("inode: {}", entry.ino());
   Ok(())
   }

Errors

The following returns an DirEntryError::IOError error when the file doesn’t exist:

use fdf::{fs::DirEntry, DirEntryError};
use std::fs;

// Verify the path doesn't exist first
let nonexistent_path = "/definitely/not/a/real/file/lalalalalalalalalalalal";
assert!(!fs::metadata(nonexistent_path).is_ok());

   // This will return an DirEntry::IOError because the file does not exist
let result = DirEntry::new(nonexistent_path);
match result {
       Ok(_) => panic!("this should never happen!"),
       Err(DirEntryError::IOError(_)) => {}, // Expected error
       Err(_) => panic!("Expected  error, got different error"),
       }

pub fn modified_time(&self) -> Result<DateTime<Utc>>

Returns the last modification time of the file in UTC.

This method performs an lstat system call to retrieve metadata for the entry. Unlike stat, it does not follow symbolic links. If the entry is a symlink, the modification time of the link itself is returned rather than that of its target.

Errors

Returns an Err if:

• The lstat call fails (for example, due to insufficient permissions or an invalid path).
• The timestamp retrieved from the OS cannot be represented as a valid DateTime<Utc>.

Notes

The timestamp is constructed using seconds (st_mtime) and nanoseconds (st_mtimensec) from the underlying stat structure. These values are cast to u32 internally to match the expected type for chrono::DateTime::from_timestamp.

Examples

use fdf::fs::DirEntry;
use chrono::Utc;

let entry = DirEntry::new("/tmp/example.txt").unwrap();
let modified = entry.modified_time().unwrap();

println!("Last modified at: {}", modified.with_timezone(&Utc));

pub fn file_size(&self) -> Result<u64>

Gets the file size in bytes.

This method retrieves the file size by calling get_lstat() and extracting the st_size field from the stat structure. Unlike get_stat(), this method does not follow symbolic links - it returns the size of the symlink itself rather than the target file.

Errors

Returns an error if:

• The file doesn’t exist
• Permission is denied
• The path is invalid
• The lstat system call fails for any other reason

Returns

The size of the file in bytes as an u64. For symbolic links, this returns the length of the symlink path itself, not the target file size.

pub fn readdir(&self) -> Result<ReadDir>

Returns an iterator over directory entries using the readdir API.

This provides a higher-level, more portable interface for directory iteration compared to getdents. Suitable for most use cases where maximum performance isn’t critical.

Errors

Returns Err if:

• The entry is not a directory
• Permission restrictions prevent reading the directory
• The directory has been removed or become inaccessible
• Any other system error occurs during directory opening/reading

Examples

use fdf::fs::DirEntry;
use std::fs::{self, File};
use std::io::Write;
use std::sync::Arc;

// Create a temporary directory with test files
let temp_dir = std::env::temp_dir().join("test_readdir");
fs::create_dir(&temp_dir).unwrap();

// Create test files
File::create(temp_dir.join("file1.txt")).unwrap().write_all(b"test").unwrap();
File::create(temp_dir.join("file2.txt")).unwrap().write_all(b"test").unwrap();
fs::create_dir(temp_dir.join("subdir")).unwrap();

// Create DirEntry for the temporary directory
let entry = DirEntry::new(&temp_dir).unwrap();

// Use readdir to iterate through directory contents
let mut entries: Vec<_> = entry.readdir().unwrap().collect();
entries.sort_by_key(|e| e.file_name().to_vec());

// Should contain 3 entries: 2 files and 1 directory
assert_eq!(entries.len(), 3);
assert!(entries.iter().any(|e| e.file_name() == b"file1.txt"));
assert!(entries.iter().any(|e| e.file_name() == b"file2.txt"));
assert!(entries.iter().any(|e| e.file_name() == b"subdir"));
fs::remove_dir_all(&temp_dir).unwrap();

pub fn getdents(&self) -> Result<GetDents>

Low-level directory iterator using the getdents64 system call.

This method provides high-performance directory scanning by using a large buffer (typically ~4.1KB) to minimise system calls. It’s Linux-specific and generally faster than readdir for bulk directory operations.

Errors

Returns Err if:

• The entry is not a directory
• Permission restrictions prevent reading the directory
• The directory file descriptor cannot be opened
• Buffer allocation fails
• Any other system error occurs during the getdents operation

Platform Specificity

This method is only available on Linux targets due to its dependence on the getdents64 system call.

Examples

use fdf::fs::DirEntry;
use std::fs::{self, File};
use std::io::Write;
use std::sync::Arc;

// Create a temporary directory with test files
let temp_dir = std::env::temp_dir().join("test_getdents");
fs::create_dir(&temp_dir).unwrap();

// Create test files
File::create(temp_dir.join("file1.txt")).unwrap().write_all(b"test").unwrap();
File::create(temp_dir.join("file2.txt")).unwrap().write_all(b"test").unwrap();
fs::create_dir(temp_dir.join("subdir")).unwrap();

// Create DirEntry for the temporary directory
let entry= DirEntry::new(&temp_dir).unwrap();

// Use getdents to iterate through directory contents
let mut entries: Vec<_> = entry.getdents().unwrap().collect();
entries.sort_by_key(|e| e.file_name().to_vec());

// Should contain 3 entries: 2 files and 1 directory
assert_eq!(entries.len(), 3);
assert!(entries.iter().any(|e| e.file_name() == b"file1.txt"));
assert!(entries.iter().any(|e| e.file_name() == b"file2.txt"));
assert!(entries.iter().any(|e| e.file_name() == b"subdir"));

// Clean up
fs::remove_dir_all(&temp_dir).unwrap();

Methods from Deref<Target = [u8]>

pub fn is_ascii(&self) -> bool

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

An empty slice returns true.

pub fn as_ascii(&self) -> Option<&[AsciiChar]>

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

If this slice is_ascii, returns it as a slice of ASCII characters, otherwise returns None.

pub unsafe fn as_ascii_unchecked(&self) -> &[AsciiChar]

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

Converts this slice of bytes into a slice of ASCII characters, without checking whether they’re valid.

Safety

Every byte in the slice must be in 0..=127, or else this is UB.

pub fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool

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<'_>

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

Examples

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 trim_ascii_start(&self) -> &[u8]

Returns a byte slice with leading ASCII whitespace bytes removed.

‘Whitespace’ refers to the definition used by u8::is_ascii_whitespace.

Examples

assert_eq!(b" \t hello world\n".trim_ascii_start(), b"hello world\n");
assert_eq!(b"  ".trim_ascii_start(), b"");
assert_eq!(b"".trim_ascii_start(), b"");

pub fn trim_ascii_end(&self) -> &[u8]

Returns a byte slice with trailing ASCII whitespace bytes removed.

‘Whitespace’ refers to the definition used by u8::is_ascii_whitespace.

Examples

assert_eq!(b"\r hello world\n ".trim_ascii_end(), b"\r hello world");
assert_eq!(b"  ".trim_ascii_end(), b"");
assert_eq!(b"".trim_ascii_end(), b"");

pub fn trim_ascii(&self) -> &[u8]

Returns a byte slice with leading and trailing ASCII whitespace bytes removed.

‘Whitespace’ refers to the definition used by u8::is_ascii_whitespace.

Examples

assert_eq!(b"\r hello world\n ".trim_ascii(), b"hello world");
assert_eq!(b"  ".trim_ascii(), b"");
assert_eq!(b"".trim_ascii(), b"");

pub fn len(&self) -> usize

Returns the number of elements in the slice.

Examples

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

pub fn is_empty(&self) -> bool

Returns true if the slice has a length of 0.

Examples

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

let b: &[i32] = &[];
assert!(b.is_empty());

pub fn first(&self) -> Option<&T>

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 fn split_first(&self) -> Option<(&T, &[T])>

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 fn split_last(&self) -> Option<(&T, &[T])>

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 fn last(&self) -> Option<&T>

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 first_chunk<const N: usize>(&self) -> Option<&[T; N]>

Returns an array reference to the first N items in the slice.

If the slice is not at least N in length, this will return None.

Examples

let u = [10, 40, 30];
assert_eq!(Some(&[10, 40]), u.first_chunk::<2>());

let v: &[i32] = &[10];
assert_eq!(None, v.first_chunk::<2>());

let w: &[i32] = &[];
assert_eq!(Some(&[]), w.first_chunk::<0>());

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

Returns an array reference to the first N items in the slice and the remaining slice.

If the slice is not at least N in length, this will return None.

Examples

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

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

assert_eq!(None, x.split_first_chunk::<4>());

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

Returns an array reference to the last N items in the slice and the remaining slice.

If the slice is not at least N in length, this will return None.

Examples

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

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

assert_eq!(None, x.split_last_chunk::<4>());

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

Returns an array reference to the last N items in the slice.

If the slice is not at least N in length, this will return None.

Examples

let u = [10, 40, 30];
assert_eq!(Some(&[40, 30]), u.last_chunk::<2>());

let v: &[i32] = &[10];
assert_eq!(None, v.last_chunk::<2>());

let w: &[i32] = &[];
assert_eq!(Some(&[]), w.last_chunk::<0>());

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

where I: SliceIndex<[T]>,

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]>,

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.

You can think of this like .get(index).unwrap_unchecked(). It’s UB to call .get_unchecked(len), even if you immediately convert to a pointer. And it’s UB to call .get_unchecked(..len + 1), .get_unchecked(..=len), or similar.

Examples

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

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

pub fn as_ptr(&self) -> *const T

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 dangling.

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 fn as_ptr_range(&self) -> Range<*const T>

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 as_array<const N: usize>(&self) -> Option<&[T; N]>

Gets a reference to the underlying array.

If N is not exactly equal to the length of self, then this method returns None.

pub fn iter(&self) -> Iter<'_, T>

Returns an iterator over the slice.

The iterator yields all items from start to end.

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>

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 zero.

Examples

let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.windows(3);
assert_eq!(iter.next().unwrap(), &['l', 'o', 'r']);
assert_eq!(iter.next().unwrap(), &['o', 'r', 'e']);
assert_eq!(iter.next().unwrap(), &['r', 'e', 'm']);
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());

Because the Iterator trait cannot represent the required lifetimes, there is no windows_mut analog to windows; [0,1,2].windows_mut(2).collect() would violate the rules of references (though a LendingIterator analog is possible). You can sometimes use Cell::as_slice_of_cells in conjunction with windows instead:

use std::cell::Cell;

let mut array = ['R', 'u', 's', 't', ' ', '2', '0', '1', '5'];
let slice = &mut array[..];
let slice_of_cells: &[Cell<char>] = Cell::from_mut(slice).as_slice_of_cells();
for w in slice_of_cells.windows(3) {
    Cell::swap(&w[0], &w[2]);
}
assert_eq!(array, ['s', 't', ' ', '2', '0', '1', '5', 'u', 'R']);

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

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.

If your chunk_size is a constant, consider using as_chunks instead, which will give references to arrays of exactly that length, rather than slices.

Panics

Panics if chunk_size is zero.

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>

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.

If your chunk_size is a constant, consider using as_chunks instead, which will give references to arrays of exactly that length, rather than slices.

Panics

Panics if chunk_size is zero.

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]]

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

This is the inverse operation to as_flattened.

As this is unsafe, consider whether you could use as_chunks or as_rchunks instead, perhaps via something like if let (chunks, []) = slice.as_chunks() or let (chunks, []) = slice.as_chunks() else { unreachable!() };.

Safety

This may only be called when

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

Examples

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])

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.

The remainder is meaningful in the division sense. Given let (chunks, remainder) = slice.as_chunks(), then:

• chunks.len() equals slice.len() / N,
• remainder.len() equals slice.len() % N, and
• slice.len() equals chunks.len() * N + remainder.len().

You can flatten the chunks back into a slice-of-T with as_flattened.

Panics

Panics if N is zero.

Note that this check is against a const generic parameter, not a runtime value, and thus a particular monomorphization will either always panic or it will never panic.

Examples

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

If you expect the slice to be an exact multiple, you can combine let-else with an empty slice pattern:

let slice = ['R', 'u', 's', 't'];
let (chunks, []) = slice.as_chunks::<2>() else {
    panic!("slice didn't have even length")
};
assert_eq!(chunks, &[['R', 'u'], ['s', 't']]);

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

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.

The remainder is meaningful in the division sense. Given let (remainder, chunks) = slice.as_rchunks(), then:

• remainder.len() equals slice.len() % N,
• chunks.len() equals slice.len() / N, and
• slice.len() equals chunks.len() * N + remainder.len().

You can flatten the chunks back into a slice-of-T with as_flattened.

Panics

Panics if N is zero.

Note that this check is against a const generic parameter, not a runtime value, and thus a particular monomorphization will either always panic or it will never panic.

Examples

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_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N>

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 zero.

Note that this check is against a const generic parameter, not a runtime value, and thus a particular monomorphization will either always panic or it will never panic.

Examples

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>

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.

If your chunk_size is a constant, consider using as_rchunks instead, which will give references to arrays of exactly that length, rather than slices.

Panics

Panics if chunk_size is zero.

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>

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 rchunks.

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.

If your chunk_size is a constant, consider using as_rchunks instead, which will give references to arrays of exactly that length, rather than slices.

Panics

Panics if chunk_size is zero.

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 chunk_by<F>(&self, pred: F) -> ChunkBy<'_, T, F>

where F: FnMut(&T, &T) -> bool,

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

The predicate is called for every pair of consecutive elements, meaning that it is called on slice[0] and slice[1], followed by slice[1] and slice[2], and so on.

Examples

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

let mut iter = slice.chunk_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:

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

let mut iter = slice.chunk_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])

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. For a non-panicking alternative see split_at_checked.

Examples

let v = ['a', 'b', 'c'];

{
   let (left, right) = v.split_at(0);
   assert_eq!(left, []);
   assert_eq!(right, ['a', 'b', 'c']);
}

{
    let (left, right) = v.split_at(2);
    assert_eq!(left, ['a', 'b']);
    assert_eq!(right, ['c']);
}

{
    let (left, right) = v.split_at(3);
    assert_eq!(left, ['a', 'b', 'c']);
    assert_eq!(right, []);
}

pub unsafe fn split_at_unchecked(&self, mid: usize) -> (&[T], &[T])

Divides one slice into two at an index, without doing bounds checking.

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).

For a safe alternative see split_at.

Safety

Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used. The caller has to ensure that 0 <= mid <= self.len().

Examples

let v = ['a', 'b', 'c'];

unsafe {
   let (left, right) = v.split_at_unchecked(0);
   assert_eq!(left, []);
   assert_eq!(right, ['a', 'b', 'c']);
}

unsafe {
    let (left, right) = v.split_at_unchecked(2);
    assert_eq!(left, ['a', 'b']);
    assert_eq!(right, ['c']);
}

unsafe {
    let (left, right) = v.split_at_unchecked(3);
    assert_eq!(left, ['a', 'b', 'c']);
    assert_eq!(right, []);
}

pub fn split_at_checked(&self, mid: usize) -> Option<(&[T], &[T])>

Divides one slice into two at an index, returning None if the slice is too short.

If mid ≤ len returns a pair of slices where 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).

Otherwise, if mid > len, returns None.

Examples

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

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

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

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

assert_eq!(None, v.split_at_checked(7));

pub fn split<F>(&self, pred: F) -> Split<'_, T, F>

where F: FnMut(&T) -> bool,

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,

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,

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,

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,

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 split_once<F>(&self, pred: F) -> Option<(&[T], &[T])>

where F: FnMut(&T) -> bool,

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

Splits the slice on the first element that matches the specified predicate.

If any matching elements are present in the slice, returns the prefix before the match and suffix after. The matching element itself is not included. If no elements match, returns None.

Examples

#![feature(slice_split_once)]
let s = [1, 2, 3, 2, 4];
assert_eq!(s.split_once(|&x| x == 2), Some((
    &[1][..],
    &[3, 2, 4][..]
)));
assert_eq!(s.split_once(|&x| x == 0), None);

pub fn rsplit_once<F>(&self, pred: F) -> Option<(&[T], &[T])>

where F: FnMut(&T) -> bool,

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

Splits the slice on the last element that matches the specified predicate.

If any matching elements are present in the slice, returns the prefix before the match and suffix after. The matching element itself is not included. If no elements match, returns None.

Examples

#![feature(slice_split_once)]
let s = [1, 2, 3, 2, 4];
assert_eq!(s.rsplit_once(|&x| x == 2), Some((
    &[1, 2, 3][..],
    &[4][..]
)));
assert_eq!(s.rsplit_once(|&x| x == 0), None);

pub fn contains(&self, x: &T) -> bool

where T: PartialEq,

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

This operation is O(n).

Note that if you have a sorted slice, binary_search may be faster.

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,

Returns true if needle is a prefix of the slice or equal to the slice.

Examples

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

Returns true if needle is a suffix of the slice or equal to the slice.

Examples

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

pub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]>

where P: SlicePattern<Item = T> + ?Sized, T: PartialEq,

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 prefix is equal to the original slice, returns an empty 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(&[10, 40, 30]), Some(&[][..]));
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()));

pub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]>

where P: SlicePattern<Item = T> + ?Sized, T: PartialEq,

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 suffix is equal to the original slice, returns an empty 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(&[10, 40, 30]), Some(&[][..]));
assert_eq!(v.strip_suffix(&[50]), None);
assert_eq!(v.strip_suffix(&[50, 30]), None);

pub fn strip_circumfix<S, P>(&self, prefix: &P, suffix: &S) -> Option<&[T]>

where T: PartialEq, S: SlicePattern<Item = T> + ?Sized, P: SlicePattern<Item = T> + ?Sized,

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

Returns a subslice with the prefix and suffix removed.

If the slice starts with prefix and ends with suffix, returns the subslice after the prefix and before the suffix, wrapped in Some.

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

Examples

#![feature(strip_circumfix)]

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

pub fn trim_prefix<P>(&self, prefix: &P) -> &[T]

where P: SlicePattern<Item = T> + ?Sized, T: PartialEq,

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

Returns a subslice with the optional prefix removed.

If the slice starts with prefix, returns the subslice after the prefix. If prefix is empty or the slice does not start with prefix, simply returns the original slice. If prefix is equal to the original slice, returns an empty slice.

Examples

#![feature(trim_prefix_suffix)]

let v = &[10, 40, 30];

// Prefix present - removes it
assert_eq!(v.trim_prefix(&[10]), &[40, 30][..]);
assert_eq!(v.trim_prefix(&[10, 40]), &[30][..]);
assert_eq!(v.trim_prefix(&[10, 40, 30]), &[][..]);

// Prefix absent - returns original slice
assert_eq!(v.trim_prefix(&[50]), &[10, 40, 30][..]);
assert_eq!(v.trim_prefix(&[10, 50]), &[10, 40, 30][..]);

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

pub fn trim_suffix<P>(&self, suffix: &P) -> &[T]

where P: SlicePattern<Item = T> + ?Sized, T: PartialEq,

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

Returns a subslice with the optional suffix removed.

If the slice ends with suffix, returns the subslice before the suffix. If suffix is empty or the slice does not end with suffix, simply returns the original slice. If suffix is equal to the original slice, returns an empty slice.

Examples

#![feature(trim_prefix_suffix)]

let v = &[10, 40, 30];

// Suffix present - removes it
assert_eq!(v.trim_suffix(&[30]), &[10, 40][..]);
assert_eq!(v.trim_suffix(&[40, 30]), &[10][..]);
assert_eq!(v.trim_suffix(&[10, 40, 30]), &[][..]);

// Suffix absent - returns original slice
assert_eq!(v.trim_suffix(&[50]), &[10, 40, 30][..]);
assert_eq!(v.trim_suffix(&[50, 30]), &[10, 40, 30][..]);

pub fn binary_search(&self, x: &T) -> Result<usize, usize>

where T: Ord,

Binary searches this slice for a given element. If the slice is not sorted, the returned result is unspecified and meaningless.

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. The index is chosen deterministically, but is subject to change in future versions of Rust. 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 find that whole range of matching items, rather than an arbitrary matching one, that can be done using partition_point:

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

let low = s.partition_point(|x| x < &1);
assert_eq!(low, 1);
let high = s.partition_point(|x| x <= &1);
assert_eq!(high, 5);
let r = s.binary_search(&1);
assert!((low..high).contains(&r.unwrap()));

assert!(s[..low].iter().all(|&x| x < 1));
assert!(s[low..high].iter().all(|&x| x == 1));
assert!(s[high..].iter().all(|&x| x > 1));

// For something not found, the "range" of equal items is empty
assert_eq!(s.partition_point(|x| x < &11), 9);
assert_eq!(s.partition_point(|x| x <= &11), 9);
assert_eq!(s.binary_search(&11), Err(9));

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

let mut s = vec![0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let num = 42;
let idx = s.partition_point(|&x| x <= num);
// If `num` is unique, `s.partition_point(|&x| x < num)` (with `<`) is equivalent to
// `s.binary_search(&num).unwrap_or_else(|x| x)`, but using `<=` will allow `insert`
// to shift less elements.
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,

Binary searches this slice with a comparator function.

The comparator function should return an order code that indicates whether its argument is Less, Equal or Greater the desired target. If the slice is not sorted or if the comparator function does not implement an order consistent with the sort order of the underlying slice, the returned result is unspecified and meaningless.

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. The index is chosen deterministically, but is subject to change in future versions of Rust. 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,

Binary searches this 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 slice is not sorted by the key, the returned result is unspecified and meaningless.

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. The index is chosen deterministically, but is subject to change in future versions of Rust. 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])

Transmutes 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 middle part will be as big as possible under the given alignment constraint and element size.

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 as_simd<const LANES: usize>(&self) -> (&[T], &[Simd<T, LANES>], &[T])

where Simd<T, LANES>: AsRef<[T; LANES]>, T: SimdElement, LaneCount<LANES>: SupportedLaneCount,

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

Splits a slice into a prefix, a middle of aligned SIMD types, and a suffix.

This is a safe wrapper around slice::align_to, so inherits the same guarantees as that method.

Panics

This will panic if the size of the SIMD type is different from LANES times that of the scalar.

At the time of writing, the trait restrictions on Simd<T, LANES> keeps that from ever happening, as only power-of-two numbers of lanes are supported. It’s possible that, in the future, those restrictions might be lifted in a way that would make it possible to see panics from this method for something like LANES == 3.

Examples

#![feature(portable_simd)]
use core::simd::prelude::*;

let short = &[1, 2, 3];
let (prefix, middle, suffix) = short.as_simd::<4>();
assert_eq!(middle, []); // Not enough elements for anything in the middle

// They might be split in any possible way between prefix and suffix
let it = prefix.iter().chain(suffix).copied();
assert_eq!(it.collect::<Vec<_>>(), vec![1, 2, 3]);

fn basic_simd_sum(x: &[f32]) -> f32 {
    use std::ops::Add;
    let (prefix, middle, suffix) = x.as_simd();
    let sums = f32x4::from_array([
        prefix.iter().copied().sum(),
        0.0,
        0.0,
        suffix.iter().copied().sum(),
    ]);
    let sums = middle.iter().copied().fold(sums, f32x4::add);
    sums.reduce_sum()
}

let numbers: Vec<f32> = (1..101).map(|x| x as _).collect();
assert_eq!(basic_simd_sum(&numbers[1..99]), 4949.0);

pub fn is_sorted(&self) -> bool

where T: PartialOrd,

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

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<'a, F>(&'a self, compare: F) -> bool

where F: FnMut(&'a T, &'a T) -> bool,

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 whether two elements are to be considered in sorted order.

Examples

assert!([1, 2, 2, 9].is_sorted_by(|a, b| a <= b));
assert!(![1, 2, 2, 9].is_sorted_by(|a, b| a < b));

assert!([0].is_sorted_by(|a, b| true));
assert!([0].is_sorted_by(|a, b| false));

let empty: [i32; 0] = [];
assert!(empty.is_sorted_by(|a, b| false));
assert!(empty.is_sorted_by(|a, b| true));

pub fn is_sorted_by_key<'a, F, K>(&'a self, f: F) -> bool

where F: FnMut(&'a T) -> K, K: PartialOrd,

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

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,

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 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)));

If all elements of the slice match the predicate, including if the slice is empty, then the length of the slice will be returned:

let a = [2, 4, 8];
assert_eq!(a.partition_point(|x| x < &100), a.len());
let a: [i32; 0] = [];
assert_eq!(a.partition_point(|x| x < &100), 0);

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

pub fn element_offset(&self, element: &T) -> Option<usize>

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

Returns the index that an element reference points to.

Returns None if element does not point to the start of an element within the slice.

This method is useful for extending slice iterators like slice::split.

Note that this uses pointer arithmetic and does not compare elements. To find the index of an element via comparison, use .iter().position() instead.

Panics

Panics if T is zero-sized.

Examples

Basic usage:

#![feature(substr_range)]

let nums: &[u32] = &[1, 7, 1, 1];
let num = &nums[2];

assert_eq!(num, &1);
assert_eq!(nums.element_offset(num), Some(2));

Returning None with an unaligned element:

#![feature(substr_range)]

let arr: &[[u32; 2]] = &[[0, 1], [2, 3]];
let flat_arr: &[u32] = arr.as_flattened();

let ok_elm: &[u32; 2] = flat_arr[0..2].try_into().unwrap();
let weird_elm: &[u32; 2] = flat_arr[1..3].try_into().unwrap();

assert_eq!(ok_elm, &[0, 1]);
assert_eq!(weird_elm, &[1, 2]);

assert_eq!(arr.element_offset(ok_elm), Some(0)); // Points to element 0
assert_eq!(arr.element_offset(weird_elm), None); // Points between element 0 and 1

pub fn subslice_range(&self, subslice: &[T]) -> Option<Range<usize>>

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

Returns the range of indices that a subslice points to.

Returns None if subslice does not point within the slice or if it is not aligned with the elements in the slice.

This method does not compare elements. Instead, this method finds the location in the slice that subslice was obtained from. To find the index of a subslice via comparison, instead use .windows().position().

This method is useful for extending slice iterators like slice::split.

Note that this may return a false positive (either Some(0..0) or Some(self.len()..self.len())) if subslice has a length of zero and points to the beginning or end of another, separate, slice.

Panics

Panics if T is zero-sized.

Examples

Basic usage:

#![feature(substr_range)]

let nums = &[0, 5, 10, 0, 0, 5];

let mut iter = nums
    .split(|t| *t == 0)
    .map(|n| nums.subslice_range(n).unwrap());

assert_eq!(iter.next(), Some(0..0));
assert_eq!(iter.next(), Some(1..3));
assert_eq!(iter.next(), Some(4..4));
assert_eq!(iter.next(), Some(5..6));

pub fn as_slice(&self) -> &[T]

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

Returns the same slice &[T].

This method is redundant when used directly on &[T], but it helps dereferencing other “container” types to slices, for example Box<[T]> or Arc<[T]>.

pub fn utf8_chunks(&self) -> Utf8Chunks<'_>

Creates an iterator over the contiguous valid UTF-8 ranges of this slice, and the non-UTF-8 fragments in between.

See the Utf8Chunk type for documentation of the items yielded by this iterator.

Examples

This function formats arbitrary but mostly-UTF-8 bytes into Rust source code in the form of a C-string literal (c"...").

use std::fmt::Write as _;

pub fn cstr_literal(bytes: &[u8]) -> String {
    let mut repr = String::new();
    repr.push_str("c\"");
    for chunk in bytes.utf8_chunks() {
        for ch in chunk.valid().chars() {
            // Escapes \0, \t, \r, \n, \\, \', \", and uses \u{...} for non-printable characters.
            write!(repr, "{}", ch.escape_debug()).unwrap();
        }
        for byte in chunk.invalid() {
            write!(repr, "\\x{:02X}", byte).unwrap();
        }
    }
    repr.push('"');
    repr
}

fn main() {
    let lit = cstr_literal(b"\xferris the \xf0\x9f\xa6\x80\x07");
    let expected = stringify!(c"\xFErris the 🦀\u{7}");
    assert_eq!(lit, expected);
}

pub fn to_vec(&self) -> Vec<T>

where T: Clone,

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 A: Allocator, T: Clone,

🔬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>

where T: Copy,

Creates a vector by copying a slice n times.

Panics

This function will panic if the capacity would overflow.

Examples

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

where [T]: Concat<Item>, Item: ?Sized,

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

where [T]: Join<Separator>,

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

where [T]: Join<Separator>,

👎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>

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>

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 DirEntry

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

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<Path> for DirEntry

fn as_ref(&self) -> &Path

Converts this type into a shared reference of the (usually inferred) input type.

impl Clone for DirEntry

fn clone(&self) -> DirEntry

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for DirEntry

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

Formats the value using the given formatter.

impl Deref for DirEntry

type Target = [u8]

The resulting type after dereferencing.

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

Dereferences the value.

impl Display for DirEntry

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

Formats the value using the given formatter.

impl<'drnt> From<&'drnt DirEntry> for &'drnt CStr

fn from(entry: &'drnt DirEntry) -> &'drnt CStr

Converts to this type from the input type.

impl From<DirEntry> for PathBuf

fn from(entry: DirEntry) -> Self

Converts to this type from the input type.

impl TryFrom<&[u8]> for DirEntry

type Error = DirEntryError

The type returned in the event of a conversion error.

fn try_from(path: &[u8]) -> Result<Self>

Performs the conversion.

impl TryFrom<&OsStr> for DirEntry

type Error = DirEntryError

The type returned in the event of a conversion error.

fn try_from(path: &OsStr) -> Result<Self>

Performs the conversion.