pub struct Argue { /* private fields */ }
Expand description
Argue
is an agnostic CLI argument parser. Unlike more robust libraries
like clap, Argue
does not hold
information about expected or required arguments; it merely parses the raw
arguments into a consistent state so the implementor can query them as
needed.
Post-processing is an exercise largely left to the implementing library to
do in its own way, in its own time. Argue
exposes several methods for
quickly querying the individual pieces of the set, but it can also be
dereferenced to a slice or consumed into an owned vector for fully manual
processing if desired.
Arguments are processed and held as bytes — Cow<'static, [u8]>
— rather
than (os)strings, again leaving the choice of later conversion entirely up
to the implementor. For non-Musl Linux systems, this is almost entirely
non-allocating as CLI arguments map directly back to the CStr
pointers.
For other systems, Argue
falls back to std::env::args_os
, so requires
a bit more allocation.
For simple applications, this agnostic approach can significantly reduce the overhead of processing CLI arguments, but because handling is left to the implementing library, it might be too tedious or limiting for more complex use cases.
Assumptions
Argue
is built for speed and simplicity, and as such, contains a number
of assumptions and limitations that might make it unsuitable for use.
Keys
A “key” is an argument entry beginning with one or two dashes -
and an
ASCII letter (A..=Z
or a..=z
). Entries with one dash are “short”, and
can only consist of two bytes. Entries with two dashes are “long” and can
be however long they want to be.
If a short key entry is longer than two bytes, everything in range 2..
is
assumed to be a value and is split off into its own entry. For example,
-kVal
is equivalent to -k Val
.
If a long key contains an =
, it is likewise assumed to be a key/value
pair, and will be split into two at that index. For example, --key=Val
is
equivalent to --key Val
.
A key without a value is called a “switch”. It is true
if present,
false
if not.
A key with one value is called an “option”. Multi-value options are not supported.
Trailing Arguments
All values beginning after the last known switch or option value are considered to be trailing arguments. Any number (including zero) of trailing arguments can be provided.
Restrictions
- Keys are not checked for uniqueness, but only the first occurrence of a given key will ever match.
- A given argument set may only include up to 15 keys. If that number is exceeded,
Argue
will print an error and terminate the thread with a status code of1
. - The total number of keys, values, and arguments may not exceed
u16::MAX
. - A glued
--key=Val
expression cannot be longer thanu16::MAX
bytes. - Argument parsing stops if a passthrough separator
--
is found. Anything up to that point is parsed as usual; everything after is discarded.
Examples
Argue
follows a builder pattern for construction, with a few odds and
ends tucked away as flags.
use std::borrow::Cow;
use argyle::{Argue, FLAG_REQUIRED};
// Parse the env arguments, aborting if the set is empty.
let args = Argue::new(FLAG_REQUIRED).unwrap();
// Check to see what's there.
let switch: bool = args.switch(b"-s");
let option: Option<&[u8]> = args.option(b"--my-opt");
let extras: &[Cow<'static, [u8]>] = args.args();
If you just want a clean set to iterate over, Argue
can be dereferenced
to a slice:
let arg_slice: &[Cow<'static, [u8]>] = *args;
Or it can be converted into an owned Vector:
let args: Vec<Cow<'static, [u8]>> = args.take();
Implementations
sourceimpl Argue
impl Argue
sourcepub fn new(flags: u8) -> Result<Self, ArgyleError>
pub fn new(flags: u8) -> Result<Self, ArgyleError>
New Instance.
For non-musl Linux targets, this populates arguments from the
environment by hooking directly into argv
, avoiding unnecessary
allocations.
For other Unix systems, this simply parses the owned output of
std::env::args_os
.
The first (command path) argument is always excluded.
Errors
This method will bubble any processing errors or aborts (like the discovery of version or help flags).
Examples
use argyle::Argue;
let args = Argue::new(0);
sourcepub fn with_flags(self, flags: u8) -> Result<Self, ArgyleError>
👎 Deprecated since 0.5.5: set flags during Argue::new
pub fn with_flags(self, flags: u8) -> Result<Self, ArgyleError>
set flags during Argue::new
With Flags.
This method can be used to set additional parsing options in cases
where the struct was initialized without calling Argue::new
.
This will only ever enable flags; it will not disable existing flags.
Errors
This method will bubble any processing errors or aborts (like the discovery of version or help flags).
Examples
use argyle::{Argue, FLAG_REQUIRED};
let args = Argue::new(0).unwrap().with_flags(FLAG_REQUIRED);
sourcepub fn with_list(self) -> Self
pub fn with_list(self) -> Self
Add Arguments From a Text File.
When chained to new()
, if either “-l” or “–list” options are found,
the subsequent value (if any) is read as a text file, and each non-
empty line within is appended to the set as additional arguments,
exactly as if they were provided directly.
No judgments are passed on the contents of the file. If a line has length, it is appended.
Note: if using this approach to seed a command with file paths, make sure those paths are absolute as their relativity will likely be lost in translation.
This method always transparently returns self
.
Examples
use argyle::Argue;
let mut args = Argue::new(0).unwrap().with_list();
sourceimpl Argue
impl Argue
Casting.
These methods convert Argue
into different data structures.
sourcepub fn take(self) -> Vec<Cow<'static, [u8]>>
pub fn take(self) -> Vec<Cow<'static, [u8]>>
Into Owned Vec.
Use this method to consume the struct and return the parsed arguments
as a Vec<Cow<[u8]>>
.
If you merely want something to iterate over, you can alternatively dereference the struct to a string slice.
Examples
use argyle::Argue;
use std::borrow::Cow;
let args: Vec<Cow<[u8]>> = Argue::new(0).unwrap().take();
sourceimpl Argue
impl Argue
Queries.
These methods allow data to be questioned and extracted.
sourcepub fn peek(&self) -> Option<&[u8]>
pub fn peek(&self) -> Option<&[u8]>
First Entry.
Borrow the first entry, if any.
Examples
use argyle::Argue;
let mut args = Argue::new(0);
if let Some("happy") = args.peek() { ... }
sourcepub unsafe fn peek_unchecked(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
pub unsafe fn peek_unchecked(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
First Entry.
Borrow the first entry without first checking for its existence.
Safety
This assumes a first argument exists; it will panic if the set is empty.
Examples
use argyle::{Argue, FLAG_REQUIRED};
let args = Argue::new(FLAG_REQUIRED).unwrap();
// This is actually safe because FLAG_REQUIRED would have errored out
// if nothing were present.
let first: &[u8] = unsafe { args.peek_unchecked() };
sourcepub fn switch2(&self, short: &[u8], long: &[u8]) -> bool
pub fn switch2(&self, short: &[u8], long: &[u8]) -> bool
Switch x2.
This is a convenience method that checks for the existence of two
switches at once, returning true
if either are present. Generally
you would use this for a flag that has both a long and short version.
Examples
use argyle::Argue;
let mut args = Argue::new(0).unwrap();
let switch: bool = args.switch2(b"-s", b"--my-switch");
sourcepub fn bitflags<'a, N, I>(&self, pairs: I) -> N where
N: BitOr<Output = N> + Default,
I: IntoIterator<Item = (&'a [u8], N)>,
pub fn bitflags<'a, N, I>(&self, pairs: I) -> N where
N: BitOr<Output = N> + Default,
I: IntoIterator<Item = (&'a [u8], N)>,
Switches As Bitflags.
If you have a lot of switches that directly correspond to bitflags, you can pass them all to this method and receive the appropriate combined flag value back.
This does not conflict with Argue::switch
; if some of your flags
require special handling you can mix-and-match calls.
Note: the default value of N
is used as a starting point. For u8
,
u16
, etc., that’s just 0
, but if using a custom type, make sure its
default state is the equivalent of “no flags”.
Examples
use argyle::Argue;
let mut args = Argue::new(0).unwrap();
let flags: u8 = args.bitflags([
(&b"-o"[..], 0b0000_0001),
(&b"-t"[..], 0b0000_0010),
]);
sourcepub fn option(&self, key: &[u8]) -> Option<&[u8]>
pub fn option(&self, key: &[u8]) -> Option<&[u8]>
Option.
Return the value corresponding to key
, if present. “Value” in this
case means the entry immediately following the key. Multi-value
options are not supported.
Note: this method is the only way Argue
knows whether or not a key
is an option (with a value) or a switch. Be sure to request all
possible options before requesting the trailing arguments to ensure
the division between named and trailing is properly set.
Examples
use argyle::Argue;
let mut args = Argue::new(0).unwrap();
let opt: Option<&[u8]> = args.option(b"--my-opt");
sourcepub fn option2(&self, short: &[u8], long: &[u8]) -> Option<&[u8]>
pub fn option2(&self, short: &[u8], long: &[u8]) -> Option<&[u8]>
Option x2.
This is a convenience method that checks for the existence of two options at once, returning the first found value, if any. Generally you would use this for a flag that has both a long and short version.
Examples
use argyle::Argue;
let mut args = Argue::new(0).unwrap();
let opt: Option<&[u8]> = args.option2(b"-o", b"--my-opt");
sourcepub fn args(&self) -> &[Cow<'static, [u8]>]
pub fn args(&self) -> &[Cow<'static, [u8]>]
Trailing Arguments.
This returns a slice from the end of the result set assumed to represent unnamed arguments. The boundary for the split is determined by the position of the last known key (or key value).
It is important to query any expected options prior to calling this method, as the existence of those options might shift the boundary.
If there are no arguments, an empty slice is returned.
Examples
use argyle::Argue;
use std::borrow::Cow;
let mut args = Argue::new(0).unwrap();
let extras: &[Cow<[u8]>] = args.args();
sourcepub fn arg(&self, idx: usize) -> Option<&[u8]>
pub fn arg(&self, idx: usize) -> Option<&[u8]>
Arg at Index.
Pluck the nth trailing argument by index (starting from zero).
Note, this is different than dereferencing the whole Argue
struct
and requesting its zero index; that would refer to the first CLI
argument of any kind, which could be a subcommand or key.
sourcepub fn first_arg(&self) -> Result<&[u8], ArgyleError>
pub fn first_arg(&self) -> Result<&[u8], ArgyleError>
First Trailing Argument.
Return the first trailing argument, or print an error and exit the thread if there isn’t one.
As with other arg-related methods, it is important to query all options first, as that helps the struct determine the boundary between named and unnamed values.
Errors
This method will return an error if there is no first argument.
Examples
use argyle::Argue;
let mut args = Argue::new(0).unwrap();
let opt: &[u8] = args.first_arg().unwrap();
sourceimpl Argue
impl Argue
sourcepub fn option_os(&self, key: &[u8]) -> Option<&OsStr>
pub fn option_os(&self, key: &[u8]) -> Option<&OsStr>
Option as OsStr
.
This works just like Argue::option
, except it returns the value as
an OsStr
instead of bytes.
sourcepub fn option2_os(&self, short: &[u8], long: &[u8]) -> Option<&OsStr>
pub fn option2_os(&self, short: &[u8], long: &[u8]) -> Option<&OsStr>
Option x2 as OsStr
.
This works just like Argue::option2
, except it returns the value as
an OsStr
instead of bytes.
sourcepub fn args_os(&self) -> ArgsOsStr<'_>ⓘNotable traits for ArgsOsStr<'a>impl<'a> Iterator for ArgsOsStr<'a> type Item = &'a OsStr;
pub fn args_os(&self) -> ArgsOsStr<'_>ⓘNotable traits for ArgsOsStr<'a>impl<'a> Iterator for ArgsOsStr<'a> type Item = &'a OsStr;
Trailing Arguments as OsStr
.
This works just like Argue::args
, except it returns an iterator
that yields OsStr
instead of bytes.
sourcepub fn arg_os(&self, idx: usize) -> Option<&OsStr>
pub fn arg_os(&self, idx: usize) -> Option<&OsStr>
Arg at Index as OsStr
.
This works just like Argue::arg
, except it returns the value as an
OsStr
instead of bytes.
sourcepub fn first_arg_os(&self) -> Result<&OsStr, ArgyleError>
pub fn first_arg_os(&self) -> Result<&OsStr, ArgyleError>
First Trailing Argument as OsStr
This works just like Argue::first_arg
except it returns the value
as an OsStr
instead of bytes.
Errors
This method will return an error if there is no first argument.
Methods from Deref<Target = [Cow<'static, [u8]>]>
sourcepub fn flatten(&self) -> &[T]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
🔬 This is a nightly-only experimental API. (slice_flatten
)
pub fn flatten(&self) -> &[T]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
slice_flatten
)Takes a &[[T; N]]
, and flattens it to a &[T]
.
Panics
This panics if the length of the resulting slice would overflow a usize
.
This is only possible when flattening a slice of arrays of zero-sized
types, and thus tends to be irrelevant in practice. If
size_of::<T>() > 0
, this will never panic.
Examples
#![feature(slice_flatten)]
assert_eq!([[1, 2, 3], [4, 5, 6]].flatten(), &[1, 2, 3, 4, 5, 6]);
assert_eq!(
[[1, 2, 3], [4, 5, 6]].flatten(),
[[1, 2], [3, 4], [5, 6]].flatten(),
);
let slice_of_empty_arrays: &[[i32; 0]] = &[[], [], [], [], []];
assert!(slice_of_empty_arrays.flatten().is_empty());
let empty_slice_of_arrays: &[[u32; 10]] = &[];
assert!(empty_slice_of_arrays.flatten().is_empty());
1.0.0 · sourcepub fn first(&self) -> Option<&T>
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());
1.5.0 · sourcepub fn split_first(&self) -> Option<(&T, &[T])>
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]);
}
1.5.0 · sourcepub fn split_last(&self) -> Option<(&T, &[T])>
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]);
}
1.0.0 · sourcepub fn last(&self) -> Option<&T>
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());
1.0.0 · sourcepub fn get<I>(&self, index: I) -> Option<&<I as SliceIndex<[T]>>::Output> where
I: SliceIndex<[T]>,
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));
1.0.0 · sourcepub unsafe fn get_unchecked<I>(
&self,
index: I
) -> &<I as SliceIndex<[T]>>::Output where
I: SliceIndex<[T]>,
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.
Examples
let x = &[1, 2, 4];
unsafe {
assert_eq!(x.get_unchecked(1), &2);
}
1.0.0 · sourcepub fn as_ptr(&self) -> *const T
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 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));
}
}
1.48.0 · sourcepub fn as_ptr_range(&self) -> Range<*const T>
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));
1.0.0 · sourcepub fn iter(&self) -> Iter<'_, T>
pub fn iter(&self) -> Iter<'_, T>
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);
1.0.0 · sourcepub fn windows(&self, size: usize) -> Windows<'_, T>
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 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());
1.0.0 · sourcepub fn chunks(&self, chunk_size: usize) -> Chunks<'_, T>
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.
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());
1.31.0 · sourcepub fn chunks_exact(&self, chunk_size: usize) -> ChunksExact<'_, T>
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.
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']);
sourcepub unsafe fn as_chunks_unchecked<const N: usize>(&self) -> &[[T; N]]
🔬 This is a nightly-only experimental API. (slice_as_chunks
)
pub unsafe fn as_chunks_unchecked<const N: usize>(&self) -> &[[T; N]]
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 (akaself.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
sourcepub fn as_chunks<const N: usize>(&self) -> (&[[T; N]], &[T])
🔬 This is a nightly-only experimental API. (slice_as_chunks
)
pub fn as_chunks<const N: usize>(&self) -> (&[[T; N]], &[T])
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']);
sourcepub fn as_rchunks<const N: usize>(&self) -> (&[T], &[[T; N]])
🔬 This is a nightly-only experimental API. (slice_as_chunks
)
pub fn as_rchunks<const N: usize>(&self) -> (&[T], &[[T; N]])
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']]);
sourcepub fn array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N>
🔬 This is a nightly-only experimental API. (array_chunks
)
pub fn array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N>
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']);
sourcepub fn array_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N>
🔬 This is a nightly-only experimental API. (array_windows
)
pub fn array_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N>
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());
1.31.0 · sourcepub fn rchunks(&self, chunk_size: usize) -> RChunks<'_, T>
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.
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());
1.31.0 · sourcepub fn rchunks_exact(&self, chunk_size: usize) -> RChunksExact<'_, T>
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 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']);
sourcepub fn group_by<F>(&self, pred: F) -> GroupBy<'_, T, F> where
F: FnMut(&T, &T) -> bool,
🔬 This is a nightly-only experimental API. (slice_group_by
)
pub fn group_by<F>(&self, pred: F) -> GroupBy<'_, T, F> where
F: FnMut(&T, &T) -> bool,
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);
1.0.0 · sourcepub fn split_at(&self, mid: usize) -> (&[T], &[T])
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
.
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, []);
}
sourcepub unsafe fn split_at_unchecked(&self, mid: usize) -> (&[T], &[T])
🔬 This is a nightly-only experimental API. (slice_split_at_unchecked
)
pub unsafe fn split_at_unchecked(&self, mid: usize) -> (&[T], &[T])
slice_split_at_unchecked
)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
#![feature(slice_split_at_unchecked)]
let v = [1, 2, 3, 4, 5, 6];
unsafe {
let (left, right) = v.split_at_unchecked(0);
assert_eq!(left, []);
assert_eq!(right, [1, 2, 3, 4, 5, 6]);
}
unsafe {
let (left, right) = v.split_at_unchecked(2);
assert_eq!(left, [1, 2]);
assert_eq!(right, [3, 4, 5, 6]);
}
unsafe {
let (left, right) = v.split_at_unchecked(6);
assert_eq!(left, [1, 2, 3, 4, 5, 6]);
assert_eq!(right, []);
}
sourcepub fn split_array_ref<const N: usize>(&self) -> (&[T; N], &[T])
🔬 This is a nightly-only experimental API. (split_array
)
pub fn split_array_ref<const N: usize>(&self) -> (&[T; N], &[T])
split_array
)Divides one slice into an array and a remainder slice at an index.
The array will contain all indices from [0, N)
(excluding
the index N
itself) and the slice will contain all
indices from [N, len)
(excluding the index len
itself).
Panics
Panics if N > len
.
Examples
#![feature(split_array)]
let v = &[1, 2, 3, 4, 5, 6][..];
{
let (left, right) = v.split_array_ref::<0>();
assert_eq!(left, &[]);
assert_eq!(right, [1, 2, 3, 4, 5, 6]);
}
{
let (left, right) = v.split_array_ref::<2>();
assert_eq!(left, &[1, 2]);
assert_eq!(right, [3, 4, 5, 6]);
}
{
let (left, right) = v.split_array_ref::<6>();
assert_eq!(left, &[1, 2, 3, 4, 5, 6]);
assert_eq!(right, []);
}
sourcepub fn rsplit_array_ref<const N: usize>(&self) -> (&[T], &[T; N])
🔬 This is a nightly-only experimental API. (split_array
)
pub fn rsplit_array_ref<const N: usize>(&self) -> (&[T], &[T; N])
split_array
)Divides one slice into an array and a remainder slice at an index from the end.
The slice will contain all indices from [0, len - N)
(excluding
the index len - N
itself) and the array will contain all
indices from [len - N, len)
(excluding the index len
itself).
Panics
Panics if N > len
.
Examples
#![feature(split_array)]
let v = &[1, 2, 3, 4, 5, 6][..];
{
let (left, right) = v.rsplit_array_ref::<0>();
assert_eq!(left, [1, 2, 3, 4, 5, 6]);
assert_eq!(right, &[]);
}
{
let (left, right) = v.rsplit_array_ref::<2>();
assert_eq!(left, [1, 2, 3, 4]);
assert_eq!(right, &[5, 6]);
}
{
let (left, right) = v.rsplit_array_ref::<6>();
assert_eq!(left, []);
assert_eq!(right, &[1, 2, 3, 4, 5, 6]);
}
1.0.0 · sourcepub fn split<F>(&self, pred: F) -> Split<'_, T, F> where
F: FnMut(&T) -> bool,
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());
1.51.0 · sourcepub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F> where
F: FnMut(&T) -> bool,
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());
1.27.0 · sourcepub fn rsplit<F>(&self, pred: F) -> RSplit<'_, T, F> where
F: FnMut(&T) -> bool,
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);
1.0.0 · sourcepub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<'_, T, F> where
F: FnMut(&T) -> bool,
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:?}");
}
1.0.0 · sourcepub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<'_, T, F> where
F: FnMut(&T) -> bool,
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:?}");
}
1.0.0 · sourcepub fn contains(&self, x: &T) -> bool where
T: PartialEq<T>,
pub fn contains(&self, x: &T) -> bool where
T: PartialEq<T>,
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"));
1.0.0 · sourcepub fn starts_with(&self, needle: &[T]) -> bool where
T: PartialEq<T>,
pub fn starts_with(&self, needle: &[T]) -> bool where
T: PartialEq<T>,
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(&[]));
1.0.0 · sourcepub fn ends_with(&self, needle: &[T]) -> bool where
T: PartialEq<T>,
pub fn ends_with(&self, needle: &[T]) -> bool where
T: PartialEq<T>,
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(&[]));
1.51.0 · sourcepub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]> where
P: SlicePattern<Item = T> + ?Sized,
T: PartialEq<T>,
pub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]> where
P: SlicePattern<Item = T> + ?Sized,
T: PartialEq<T>,
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()));
1.51.0 · sourcepub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]> where
P: SlicePattern<Item = T> + ?Sized,
T: PartialEq<T>,
pub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]> where
P: SlicePattern<Item = T> + ?Sized,
T: PartialEq<T>,
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);
1.0.0 · sourcepub fn binary_search(&self, x: &T) -> Result<usize, usize> where
T: Ord,
pub fn binary_search(&self, x: &T) -> Result<usize, usize> where
T: Ord,
Binary searches this slice for a given element.
This behaves similary to contains
if this slice is sorted.
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 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);
// The above is equivalent to `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]);
1.0.0 · sourcepub fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize> where
F: FnMut(&'a T) -> Ordering,
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.
This behaves similarly to contains
if this slice is sorted.
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. 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, });
1.10.0 · sourcepub 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,
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.
This behaves similarly to contains
if this slice is sorted.
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. 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, });
1.30.0 · sourcepub unsafe fn align_to<U>(&self) -> (&[T], &[U], &[T])
pub unsafe fn align_to<U>(&self) -> (&[T], &[U], &[T])
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);
}
sourcepub fn as_simd<const LANES: usize>(&self) -> (&[T], &[Simd<T, LANES>], &[T]) where
T: SimdElement,
Simd<T, LANES>: AsRef<[T; LANES]>,
LaneCount<LANES>: SupportedLaneCount,
🔬 This is a nightly-only experimental API. (portable_simd
)
pub fn as_simd<const LANES: usize>(&self) -> (&[T], &[Simd<T, LANES>], &[T]) where
T: SimdElement,
Simd<T, LANES>: AsRef<[T; LANES]>,
LaneCount<LANES>: SupportedLaneCount,
portable_simd
)Split a slice into a prefix, a middle of aligned SIMD types, and a suffix.
This is a safe wrapper around slice::align_to
, so has the same weak
postconditions as that method. You’re only assured that
self.len() == prefix.len() + middle.len() * LANES + suffix.len()
.
Notably, all of the following are possible:
prefix.len() >= LANES
.middle.is_empty()
despiteself.len() >= 3 * LANES
.suffix.len() >= LANES
.
That said, this is a safe method, so if you’re only writing safe code, then this can at most cause incorrect logic, not unsoundness.
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)]
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;
use std::simd::f32x4;
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);
sourcepub fn is_sorted(&self) -> bool where
T: PartialOrd<T>,
🔬 This is a nightly-only experimental API. (is_sorted
)
pub fn is_sorted(&self) -> bool where
T: PartialOrd<T>,
is_sorted
)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());
sourcepub fn is_sorted_by<F>(&self, compare: F) -> bool where
F: FnMut(&T, &T) -> Option<Ordering>,
🔬 This is a nightly-only experimental API. (is_sorted
)
pub fn is_sorted_by<F>(&self, compare: F) -> bool where
F: FnMut(&T, &T) -> Option<Ordering>,
is_sorted
)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.
sourcepub fn is_sorted_by_key<F, K>(&self, f: F) -> bool where
F: FnMut(&T) -> K,
K: PartialOrd<K>,
🔬 This is a nightly-only experimental API. (is_sorted
)
pub fn is_sorted_by_key<F, K>(&self, f: F) -> bool where
F: FnMut(&T) -> K,
K: PartialOrd<K>,
is_sorted
)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()));
1.52.0 · sourcepub fn partition_point<P>(&self, pred: P) -> usize where
P: FnMut(&T) -> bool,
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 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)));
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]);
1.23.0 · sourcepub fn is_ascii(&self) -> bool
pub fn is_ascii(&self) -> bool
Checks if all bytes in this slice are within the ASCII range.
1.23.0 · sourcepub fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool
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.
1.60.0 · sourcepub fn escape_ascii(&self) -> EscapeAscii<'_>
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");
sourcepub fn trim_ascii_start(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
🔬 This is a nightly-only experimental API. (byte_slice_trim_ascii
)
pub fn trim_ascii_start(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
byte_slice_trim_ascii
)Returns a byte slice with leading ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
Examples
#![feature(byte_slice_trim_ascii)]
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"");
sourcepub fn trim_ascii_end(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
🔬 This is a nightly-only experimental API. (byte_slice_trim_ascii
)
pub fn trim_ascii_end(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
byte_slice_trim_ascii
)Returns a byte slice with trailing ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
Examples
#![feature(byte_slice_trim_ascii)]
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"");
sourcepub fn trim_ascii(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
🔬 This is a nightly-only experimental API. (byte_slice_trim_ascii
)
pub fn trim_ascii(&self) -> &[u8]ⓘNotable traits for &'_ [u8]impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]
byte_slice_trim_ascii
)Returns a byte slice with leading and trailing ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
Examples
#![feature(byte_slice_trim_ascii)]
assert_eq!(b"\r hello world\n ".trim_ascii(), b"hello world");
assert_eq!(b" ".trim_ascii(), b"");
assert_eq!(b"".trim_ascii(), b"");
1.0.0 · sourcepub fn to_vec(&self) -> Vec<T, Global> where
T: Clone,
pub fn to_vec(&self) -> Vec<T, Global> 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.
sourcepub 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
)
pub fn to_vec_in<A>(&self, alloc: A) -> Vec<T, A> where
A: Allocator,
T: Clone,
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.
1.0.0 · sourcepub 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>,
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>,
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]);
1.3.0 · sourcepub 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>,
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>,
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]);
1.0.0 · sourcepub 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>,
👎 Deprecated since 1.3.0: renamed to join
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>,
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]);
1.23.0 · sourcepub fn to_ascii_uppercase(&self) -> Vec<u8, Global>
pub fn to_ascii_uppercase(&self) -> Vec<u8, Global>
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
.
1.23.0 · sourcepub fn to_ascii_lowercase(&self) -> Vec<u8, Global>
pub fn to_ascii_lowercase(&self) -> Vec<u8, Global>
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
Auto Trait Implementations
impl !RefUnwindSafe for Argue
impl Send for Argue
impl !Sync for Argue
impl Unpin for Argue
impl UnwindSafe for Argue
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<T> ToOwned for T where
T: Clone,
impl<T> ToOwned for T where
T: Clone,
type Owned = T
type Owned = T
The resulting type after obtaining ownership.
sourcefn clone_into(&self, target: &mut T)
fn clone_into(&self, target: &mut T)
toowned_clone_into
)Uses borrowed data to replace owned data, usually by cloning. Read more