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.
(It is effectively a wrapper around std::env::args_os
.)
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 owned bytes rather than (os)strings, again leaving the choice of later conversion entirely up to the implementor.
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.
- 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 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: &[Vec<u8>] = args.args();
If you just want a clean set to iterate over, Argue
can be dereferenced
to a slice:
let arg_slice: &[Vec<u8>] = &args;
Or it can be converted into an owned Vector:
let args: Vec<Vec<u8>> = args.take();
Implementations§
source§impl Argue
impl Argue
§Instantiation and Builder Patterns.
sourcepub fn new(chk_flags: u8) -> Result<Self, ArgyleError>
pub fn new(chk_flags: u8) -> Result<Self, ArgyleError>
§New Instance.
This simply parses the owned output of std::env::args_os
.
§Examples
use argyle::{Argue, ArgyleError, FLAG_VERSION};
// Parse, but abort if -V/--version is present.
let args = match Argue::new(FLAG_VERSION) {
Ok(a) => a, // No abort.
// The version flags were present.
Err(ArgyleError::WantsVersion) => {
println!("MyApp v{}", env!("CARGO_PKG_VERSION"));
return;
},
// This probably won't happen with only FLAG_VERSION set, but just
// in case…
Err(e) => {
println!("Error: {}", e);
return;
},
};
// If we're here, check whatever random args your program needs.
let quiet: bool = args.switch(b"-q");
let foo: Option<&[u8]> = args.option2(b"-f", b"--foo");
§Errors
This method’s result may represent an actual error, or some form of
abort, such as the presence of -V
/--version
when FLAG_VERSION
was passed to the constructor.
Generally you’d want to match the specific ArgyleError
variant to
make sure you’re taking the appropriate action.
sourcepub fn with_list(self) -> Self
pub fn with_list(self) -> Self
§With “Trailing” Arguments From a Text File or STDIN.
Read lines from the text file — or STDIN if “-” — specified by the
built-in -l
/--list
option (if present), appending them to the set
as “trailing” arguments. (One argument per line.)
These arguments, if any, along with anything the user included in the
actual command, will then be accessible the usual way, via methods like
Argue::args
, etc.
Note that the input must be valid UTF-8. Its lines will be trimmed and checked for length before inclusion, but won’t otherwise be altered.
§Examples
use argyle::Argue;
let mut args = Argue::new(0).unwrap().with_list();
for arg in args.args() {
// Do something…
}
sourcepub fn with_trailing_args<B, I>(self, args: I) -> Self
pub fn with_trailing_args<B, I>(self, args: I) -> Self
§With “Trailing” Arguments.
Append arbitrary strings to the set as “trailing” arguments, making
them — along with anything the user included in the actual command —
available via methods like Argue::args
, etc.
Note that arguments are trimmed and checked for length before being added, but are otherwise passed through as-are.
§Examples
use argyle::Argue;
let mut args = Argue::new(0)
.unwrap()
.with_trailing_args(&["apples", "bananas", "carrots"]);
sourcepub fn check_keys(&self, switches: &[&[u8]], options: &[&[u8]]) -> Option<&[u8]>
pub fn check_keys(&self, switches: &[&[u8]], options: &[&[u8]]) -> Option<&[u8]>
§Verify Keys.
Return the first key-like entry in the collection that is not a valid switch or option.
Key-like, in this context, means anything beginning with one or two dashes, followed by an ASCII letter, that does not directly follow a valid option (as that would make it a value).
Note: depending on the context, this may return a false positive. For example, a program expecting file paths as trailing arguments might receive something key-like-but-not-a-key like “–foo.jpg”.
source§impl Argue
impl Argue
§Casting.
These methods convert Argue
into different data structures.
sourcepub fn take(self) -> Vec<Vec<u8>>
pub fn take(self) -> Vec<Vec<u8>>
§Into Owned Vec.
Use this method to consume the struct and return the parsed arguments
as a Vec<Vec<u8>>
.
If you merely want something to iterate over, you can alternatively dereference the struct to a string slice.
If you’re only interested in the trailing arguments, use
Argue::take_trailing
instead.
§Examples
use argyle::Argue;
let args: Vec<Vec<u8>> = Argue::new(0).unwrap().take();
sourcepub fn take_trailing(self) -> Vec<Vec<u8>>
pub fn take_trailing(self) -> Vec<Vec<u8>>
§Take Trailing Arguments.
Split off and return the instance’s (owned) trailing arguments, discarding everything else.
As with other trailing argument-related methods, make sure you query expected options before calling this method, otherwise it might mistake a final associated value for a trailing argument.
Of course, that matters less here than elsewhere since you’ll lose access to the switches and options anyway. Haha.
If you want everything, use Argue::take
instead.
§Examples
use argyle::Argue;
let trailing: Vec<Vec<u8>> = Argue::new(0).unwrap().take_trailing();
source§impl Argue
impl Argue
§Queries.
These methods allow data to be questioned and extracted.
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 switch_count(&self, key: &[u8]) -> usize
pub fn switch_count(&self, key: &[u8]) -> usize
sourcepub fn switch2_count(&self, short: &[u8], long: &[u8]) -> usize
pub fn switch2_count(&self, short: &[u8], long: &[u8]) -> usize
sourcepub fn switch_by_prefix(&self, prefix: &[u8]) -> Option<&[u8]>
pub fn switch_by_prefix(&self, prefix: &[u8]) -> Option<&[u8]>
§Switch By Prefix.
If you have multiple, mutually exclusive switches that all begin with the same prefix, this method can be used to quickly return the first match (stripped of the common prefix).
If no match is found, or an exact match is found — i.e. leaving the
key empty — None
is returned.
Do not use this if you have options sharing this prefix; Argue
doesn’t know the difference so will simply return whatever it finds
first.
§Examples
use argyle::Argue;
let mut args = Argue::new(0).unwrap();
match args.switch_by_prefix(b"--dump-") {
Some(b"addresses") => {}, // --dump-addresses
Some(b"names") => {}, // --dump-names
_ => {}, // No matches.
}
sourcepub fn bitflags<'a, N, I>(&self, pairs: I) -> N
pub fn bitflags<'a, N, I>(&self, pairs: I) -> 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.
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.
This will only ever match the last occurrence. For options that
may be specified more than once, use Argue::option_values
instead.
§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.
This will only ever match the last occurrence. For options that
may be specified more than once, use Argue::option2_values
instead.
§Examples
use argyle::Argue;
let mut args = Argue::new(0).unwrap();
let opt: Option<&[u8]> = args.option2(b"-o", b"--my-opt");
sourcepub fn option_values<'a>(
&'a self,
key: &'a [u8],
delimiter: Option<u8>,
) -> Options<'a> ⓘ
pub fn option_values<'a>( &'a self, key: &'a [u8], delimiter: Option<u8>, ) -> Options<'a> ⓘ
§Option Value(s) Iterator.
Return any and all values corresponding to key
(meaning the entries
immediately following each instance of key
).
This is useful for programs that accept the same flag multiple times, or those expecting a byte-delimited value, like a comma-separated list.
When using delimiter
, each value will be carved up by the specified
byte and returned separately.
§Examples
use argyle::Argue;
let mut args = Argue::new(0).unwrap();
for v in args.option_values(b"--my-option", None) {
println!("{:?}", std::str::from_utf8(v));
}
sourcepub fn option2_values<'a>(
&'a self,
short: &'a [u8],
long: &'a [u8],
delimiter: Option<u8>,
) -> Options<'a> ⓘ
pub fn option2_values<'a>( &'a self, short: &'a [u8], long: &'a [u8], delimiter: Option<u8>, ) -> Options<'a> ⓘ
§Option 2x Value(s) Iterator.
Return any and all values corresponding to either the short
or long
version of a key (meaning the entries immediately following each
instance of them).
This is useful for programs that accept the same flag multiple times, or those expecting a byte-delimited value, like a comma-separated list.
When using delimiter
, each value will be carved up by the specified
byte and returned separately.
§Examples
use argyle::Argue;
let mut args = Argue::new(0).unwrap();
for v in args.option2_values(b"-o", b"--my-opt", None) {
println!("{:?}", std::str::from_utf8(v));
}
sourcepub fn option_by_prefix(&self, prefix: &[u8]) -> Option<(&[u8], &[u8])>
pub fn option_by_prefix(&self, prefix: &[u8]) -> Option<(&[u8], &[u8])>
§Option By Prefix.
If you have multiple, mutually exclusive options that all begin with the same prefix, this method can be used to quickly return the first matching key (stripped of the common prefix) and value.
If no match is found, an exact match is found — i.e. leaving the
key empty — or no value follows, None
is returned.
Do not use this if you have switches sharing this prefix; Argue
doesn’t know the difference so will simply return whatever it finds
first.
§Examples
use argyle::Argue;
let mut args = Argue::new(0).unwrap();
match args.option_by_prefix(b"--color-") {
Some((b"solid", val)) => {}, // --color-solid, green
Some((b"dashed", val)) => {}, // --color-dashed, blue
_ => {}, // No matches.
}
sourcepub fn args(&self) -> &[Vec<u8>]
pub fn args(&self) -> &[Vec<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;
let mut args = Argue::new(0).unwrap();
let extras: &[Vec<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.
source§impl Argue
impl Argue
§Misc Indexing.
sourcepub fn get(&self, idx: usize) -> Option<&[u8]>
pub fn get(&self, idx: usize) -> Option<&[u8]>
§Get Argument.
This is the non-panicking way to index into a specific subcommand, key,
value, etc. It will be returned if it exists, otherwise you’ll get None
if the index is out of range.
If you know the index is valid, you can leverage the std::ops::Index
trait to fetch the value directly.
source§impl Argue
impl Argue
§OsStr
Methods.
sourcepub fn switch_by_prefix_os(&self, prefix: &[u8]) -> Option<&OsStr>
pub fn switch_by_prefix_os(&self, prefix: &[u8]) -> Option<&OsStr>
§Switch Starting With… as OsStr
.
This works just like Argue::switch_by_prefix
, except it returns the
value as an OsStr
instead of bytes.
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 option_values_os<'a>(
&'a self,
key: &'a [u8],
delimiter: Option<u8>,
) -> OptionsOsStr<'a> ⓘ
pub fn option_values_os<'a>( &'a self, key: &'a [u8], delimiter: Option<u8>, ) -> OptionsOsStr<'a> ⓘ
§Option Value(s) Iterator.
This works just like Argue::option_values
, except it returns the value
as an OsStr
instead of bytes.
sourcepub fn option2_values_os<'a>(
&'a self,
short: &'a [u8],
long: &'a [u8],
delimiter: Option<u8>,
) -> OptionsOsStr<'a> ⓘ
pub fn option2_values_os<'a>( &'a self, short: &'a [u8], long: &'a [u8], delimiter: Option<u8>, ) -> OptionsOsStr<'a> ⓘ
§Option 2x Value(s) Iterator.
This works just like Argue::option2_values
, except it returns the value
as an OsStr
instead of bytes.
sourcepub fn option_by_prefix_os(&self, prefix: &[u8]) -> Option<(&OsStr, &OsStr)>
pub fn option_by_prefix_os(&self, prefix: &[u8]) -> Option<(&OsStr, &OsStr)>
§Option Starting With… as OsStr
.
This works just like Argue::option_by_prefix
, except it returns the
key/value as OsStr
instead of bytes.
Methods from Deref<Target = [Vec<u8>]>§
sourcepub fn as_str(&self) -> &str
🔬This is a nightly-only experimental API. (ascii_char
)
pub fn as_str(&self) -> &str
ascii_char
)Views this slice of ASCII characters as a UTF-8 str
.
sourcepub fn as_bytes(&self) -> &[u8] ⓘ
🔬This is a nightly-only experimental API. (ascii_char
)
pub fn as_bytes(&self) -> &[u8] ⓘ
ascii_char
)Views this slice of ASCII characters as a slice of u8
bytes.
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.
sourcepub fn as_ascii(&self) -> Option<&[AsciiChar]>
🔬This is a nightly-only experimental API. (ascii_char
)
pub fn as_ascii(&self) -> Option<&[AsciiChar]>
ascii_char
)If this slice is_ascii
, returns it as a slice of
ASCII characters, otherwise returns None
.
sourcepub unsafe fn as_ascii_unchecked(&self) -> &[AsciiChar]
🔬This is a nightly-only experimental API. (ascii_char
)
pub unsafe fn as_ascii_unchecked(&self) -> &[AsciiChar]
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.
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");
1.80.0 · sourcepub fn trim_ascii_start(&self) -> &[u8] ⓘ
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"");
1.80.0 · sourcepub fn trim_ascii_end(&self) -> &[u8] ⓘ
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"");
1.80.0 · sourcepub fn trim_ascii(&self) -> &[u8] ⓘ
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"");
1.0.0 · sourcepub fn is_empty(&self) -> bool
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());
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());
1.77.0 · sourcepub fn first_chunk<const N: usize>(&self) -> Option<&[T; N]>
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>());
1.77.0 · sourcepub fn split_first_chunk<const N: usize>(&self) -> Option<(&[T; N], &[T])>
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>());
1.77.0 · sourcepub fn split_last_chunk<const N: usize>(&self) -> Option<(&[T], &[T; N])>
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>());
1.77.0 · sourcepub fn last_chunk<const N: usize>(&self) -> Option<&[T; N]>
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>());
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]>>::Outputwhere
I: SliceIndex<[T]>,
pub unsafe fn get_unchecked<I>(
&self,
index: I,
) -> &<I as SliceIndex<[T]>>::Outputwhere
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);
}
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 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));
}
}
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.
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);
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 = ['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());
There’s no windows_mut
, as that existing would let safe code violate the
“only one &mut
at a time to the same thing” rule. However, you can sometimes
use Cell::as_slice_of_cells
in
conjunction with windows
to accomplish something similar:
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']);
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']);
If you expect the slice to be an exact multiple, you can combine
let
-else
with an empty slice pattern:
#![feature(slice_as_chunks)]
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']]);
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 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.
§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']);
1.77.0 · sourcepub fn chunk_by<F>(&self, pred: F) -> ChunkBy<'_, T, F>
pub fn chunk_by<F>(&self, pred: F) -> ChunkBy<'_, T, F>
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);
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
. For a non-panicking alternative see
split_at_checked
.
§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, []);
}
1.79.0 · sourcepub unsafe fn split_at_unchecked(&self, mid: usize) -> (&[T], &[T])
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 = [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, []);
}
1.80.0 · sourcepub fn split_at_checked(&self, mid: usize) -> Option<(&[T], &[T])>
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));
1.0.0 · sourcepub fn split<F>(&self, pred: F) -> Split<'_, T, F>
pub fn split<F>(&self, pred: F) -> Split<'_, T, F>
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>
pub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F>
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>
pub fn rsplit<F>(&self, pred: F) -> RSplit<'_, T, F>
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>
pub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<'_, T, F>
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>
pub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<'_, T, F>
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:?}");
}
sourcepub fn split_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
🔬This is a nightly-only experimental API. (slice_split_once
)
pub fn split_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
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);
sourcepub fn rsplit_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
🔬This is a nightly-only experimental API. (slice_split_once
)
pub fn rsplit_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
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);
1.0.0 · sourcepub fn contains(&self, x: &T) -> boolwhere
T: PartialEq,
pub fn contains(&self, x: &T) -> boolwhere
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"));
1.0.0 · sourcepub fn starts_with(&self, needle: &[T]) -> boolwhere
T: PartialEq,
pub fn starts_with(&self, needle: &[T]) -> boolwhere
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(&[]));
1.0.0 · sourcepub fn ends_with(&self, needle: &[T]) -> boolwhere
T: PartialEq,
pub fn ends_with(&self, needle: &[T]) -> boolwhere
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(&[]));
1.51.0 · sourcepub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]>
pub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[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 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()));
1.51.0 · sourcepub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]>
pub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[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 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);
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. 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]);
1.0.0 · sourcepub fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize>
pub fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize>
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, });
1.10.0 · sourcepub fn binary_search_by_key<'a, B, F>(
&'a self,
b: &B,
f: F,
) -> Result<usize, usize>
pub fn binary_search_by_key<'a, B, F>( &'a self, b: &B, f: F, ) -> Result<usize, usize>
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, });
1.30.0 · sourcepub unsafe fn align_to<U>(&self) -> (&[T], &[U], &[T])
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);
}
sourcepub fn as_simd<const LANES: usize>(&self) -> (&[T], &[Simd<T, LANES>], &[T])
🔬This is a nightly-only experimental API. (portable_simd
)
pub fn as_simd<const LANES: usize>(&self) -> (&[T], &[Simd<T, LANES>], &[T])
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);
1.83.0 · sourcepub fn is_sorted(&self) -> boolwhere
T: PartialOrd,
pub fn is_sorted(&self) -> boolwhere
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());
1.83.0 · sourcepub fn is_sorted_by<'a, F>(&'a self, compare: F) -> bool
pub fn is_sorted_by<'a, F>(&'a self, compare: F) -> 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));
1.83.0 · sourcepub fn is_sorted_by_key<'a, F, K>(&'a self, f: F) -> bool
pub fn is_sorted_by_key<'a, F, K>(&'a self, f: F) -> bool
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()));
1.52.0 · sourcepub fn partition_point<P>(&self, pred: P) -> usize
pub fn partition_point<P>(&self, pred: P) -> usize
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]);
sourcepub fn elem_offset(&self, element: &T) -> Option<usize>
🔬This is a nightly-only experimental API. (substr_range
)
pub fn elem_offset(&self, element: &T) -> Option<usize>
substr_range
)Returns the index that an element reference points to.
Returns None
if element
does not point within the slice or if it points between elements.
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.elem_offset(num), Some(2));
Returning None
with an in-between 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.elem_offset(ok_elm), Some(0)); // Points to element 0
assert_eq!(arr.elem_offset(weird_elm), None); // Points between element 0 and 1
sourcepub fn subslice_range(&self, subslice: &[T]) -> Option<Range<usize>>
🔬This is a nightly-only experimental API. (substr_range
)
pub fn subslice_range(&self, subslice: &[T]) -> Option<Range<usize>>
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 points between elements.
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));
1.80.0 · sourcepub fn as_flattened(&self) -> &[T]
pub fn as_flattened(&self) -> &[T]
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
assert_eq!([[1, 2, 3], [4, 5, 6]].as_flattened(), &[1, 2, 3, 4, 5, 6]);
assert_eq!(
[[1, 2, 3], [4, 5, 6]].as_flattened(),
[[1, 2], [3, 4], [5, 6]].as_flattened(),
);
let slice_of_empty_arrays: &[[i32; 0]] = &[[], [], [], [], []];
assert!(slice_of_empty_arrays.as_flattened().is_empty());
let empty_slice_of_arrays: &[[u32; 10]] = &[];
assert!(empty_slice_of_arrays.as_flattened().is_empty());
1.79.0 · sourcepub fn utf8_chunks(&self) -> Utf8Chunks<'_>
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.
§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);
}
1.0.0 · sourcepub fn to_vec(&self) -> Vec<T>where
T: Clone,
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.
sourcepub fn to_vec_in<A>(&self, alloc: A) -> Vec<T, A>
🔬This is a nightly-only experimental API. (allocator_api
)
pub fn to_vec_in<A>(&self, alloc: A) -> Vec<T, A>
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 ⓘ
pub fn concat<Item>(&self) -> <[T] as Concat<Item>>::Output ⓘ
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 ⓘ
pub fn join<Separator>( &self, sep: Separator, ) -> <[T] as Join<Separator>>::Output ⓘ
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 ⓘ
👎Deprecated since 1.3.0: renamed to join
pub fn connect<Separator>( &self, sep: Separator, ) -> <[T] as Join<Separator>>::Output ⓘ
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>
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
.
1.23.0 · sourcepub fn to_ascii_lowercase(&self) -> Vec<u8>
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§
source§impl<'a> FromIterator<&'a [u8]> for Argue
impl<'a> FromIterator<&'a [u8]> for Argue
source§impl FromIterator<OsString> for Argue
impl FromIterator<OsString> for Argue
source§impl Index<usize> for Argue
impl Index<usize> for Argue
source§fn index(&self, idx: usize) -> &Self::Output
fn index(&self, idx: usize) -> &Self::Output
§Argument by Index.
This returns the nth CLI argument, which could be a subcommand, key, value, or trailing argument.
If you’re only interested in trailing arguments, use Argue::arg
instead.
If you want everything, you can alternatively dereference Argue
into a slice.
§Panics
This will panic if the index is out of range. Use Argue::len
to
confirm the length ahead of time, or Argue::get
, which wraps the
answer in an Option
instead of panicking.
Auto Trait Implementations§
impl !Freeze for Argue
impl !RefUnwindSafe for Argue
impl Send for Argue
impl !Sync for Argue
impl Unpin for Argue
impl UnwindSafe for Argue
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
source§impl<T> CloneToUninit for Twhere
T: Clone,
impl<T> CloneToUninit for Twhere
T: Clone,
source§unsafe fn clone_to_uninit(&self, dst: *mut T)
unsafe fn clone_to_uninit(&self, dst: *mut T)
clone_to_uninit
)