Struct fyi_msg::Msg [−][src]
pub struct Msg(_);
Expand description
Message.
The Msg
struct provides a partitioned, contiguous byte source to hold
arbitrary messages of the “Error: Oh no!” variety. They can be modified
efficiently in place (per-part) and printed to STDOUT
with Msg::print
or STDERR
with Msg::eprint
.
Take a look at examples/msg
, which covers just about all the standard use
cases.
There are two crate feature gates that augment this struct (at the expense of additional dependencies):
fitted
adds theMsg::fitted
method, which returns a byte slice that should fit within a given display width, shrinking the message part of the message as necessary to make room (leaving prefixes and suffixes in tact).timestamps
addsMsg::with_timestamp
andMsg::set_timestamp
methods for adding a local datetime value before the prefix.
Everything else comes stock!
Examples
use fyi_msg::{Msg, MsgKind}; Msg::new(MsgKind::Success, "You did it!") .with_newline(true) .print();
There are a bunch of built-in prefix types, each of which (except
MsgKind::Confirm
) has a corresponding “quick” method on this struct,
like Msg::error
, Msg::success
, etc. See MsgKind
for the full
list. These are equivalent to chaining Msg::new
and Msg::with_newline
for the given type.
Confirmations have a convenience macro instead, confirm
,
that handles all the setup and prompting, returning a simple bool
indicating the yes/noness of the user response.
Again, the examples/msg
demo covers just about all the possibilities.
Conversion
While Msg
objects are perfectly usable as-is, they can be easily
converted to other formats. They dereference to a byte slice and implement
AsRef<[u8]>
and Borrow<[u8]>
. They also implement AsRef<str>
and
Borrow<str>
for stringy situations. And if you want to consume the struct
into an owned type, there’s also Msg::into_vec
and Msg::into_string
.
Implementations
New Message.
This creates a new message with a built-in prefix (which can be
MsgKind::None
, though in that case, Msg::plain
is better).
If your prefix choice is built-in and known at compile time and you
want the message to have a trailing line break, consider using the
corresponding dedicated method instead (Msg::error
, Msg::success
,
etc.), as it will be slightly faster.
Examples
use fyi_msg::{Msg, MsgKind}; let msg = Msg::new(MsgKind::Info, "This is a message.");
Custom Prefix.
This creates a new message with a user-defined prefix and color. See here for a BASH color code primer.
The prefix you provide will automatically have a ": "
added to the
end, so you should pass “Prefix” rather than “Prefix:”.
If you don’t like the colonics, use Msg::custom_preformatted
instead.
Examples
use fyi_msg::{Msg, MsgKind}; let msg = Msg::custom("Prefix", 199, "This message has a pink prefix.");
Custom Prefix (Pre-formatted)
Same as Msg::custom
, except no validation or formatting is applied
to the provided prefix. This can be useful in cases where the prefix
requires special spacing, delimiters, or formatting that don’t match
the default format.
It is worth noting that when using this method, you must provide the punctuation and space that will separate the prefix and message parts, otherwise you’ll end up with “prefixmessage” glued together.
Examples
use fyi_msg::{Msg, MsgKind}; let msg = Msg::custom_preformatted( "e.g. ", "This message has an unformatted prefix." );
New Message Without Any Prefix.
This is a streamlined equivalent of calling Msg::new
with a
MsgKind::None
.
Examples
use fyi_msg::Msg; let msg = Msg::plain("This message has no prefix.");
Built-ins.
This contains convenience methods for creating a new message with a
built-in prefix and trailing line break. All of the stock kinds are covered
except for MsgKind::Confirm
, which does not have trailing line breaks
in its prompt form, and is kind of weird to use without a prompt.
Speaking of, there is a dedicated confirm
macro, that
renders the message with the right prefix, pops the prompt, and returns the
bool
.
New Crunched
This is a convenience method to create a thusly prefixed message with a trailing line break.
This is equivalent to combining Msg::new
with Msg::with_newline
,
but optimized for this specific prefix.
Examples
use fyi_msg::Msg; Msg::crunched("Hello World").print(); // Crunched: Hello World
New Debug
This is a convenience method to create a thusly prefixed message with a trailing line break.
This is equivalent to combining Msg::new
with Msg::with_newline
,
but optimized for this specific prefix.
Examples
use fyi_msg::Msg; Msg::debug("Hello World").print(); // Debug: Hello World
New Done
This is a convenience method to create a thusly prefixed message with a trailing line break.
This is equivalent to combining Msg::new
with Msg::with_newline
,
but optimized for this specific prefix.
Examples
use fyi_msg::Msg; Msg::done("Hello World").print(); // Done: Hello World
New Info
This is a convenience method to create a thusly prefixed message with a trailing line break.
This is equivalent to combining Msg::new
with Msg::with_newline
,
but optimized for this specific prefix.
Examples
use fyi_msg::Msg; Msg::info("Hello World").print(); // Info: Hello World
New Error
This is a convenience method to create a thusly prefixed message with a trailing line break.
This is equivalent to combining Msg::new
with Msg::with_newline
,
but optimized for this specific prefix.
Examples
use fyi_msg::Msg; Msg::error("Hello World").print(); // Error: Hello World
New Notice
This is a convenience method to create a thusly prefixed message with a trailing line break.
This is equivalent to combining Msg::new
with Msg::with_newline
,
but optimized for this specific prefix.
Examples
use fyi_msg::Msg; Msg::notice("Hello World").print(); // Notice: Hello World
New Success
This is a convenience method to create a thusly prefixed message with a trailing line break.
This is equivalent to combining Msg::new
with Msg::with_newline
,
but optimized for this specific prefix.
Examples
use fyi_msg::Msg; Msg::success("Hello World").print(); // Success: Hello World
New Task
This is a convenience method to create a thusly prefixed message with a trailing line break.
This is equivalent to combining Msg::new
with Msg::with_newline
,
but optimized for this specific prefix.
Examples
use fyi_msg::Msg; Msg::task("Hello World").print(); // Task: Hello World
New Warning
This is a convenience method to create a thusly prefixed message with a trailing line break.
This is equivalent to combining Msg::new
with Msg::with_newline
,
but optimized for this specific prefix.
Examples
use fyi_msg::Msg; Msg::warning("Hello World").print(); // Warning: Hello World
With Flags.
This can be used to quickly set indentation, timestamps, and/or a trailing line break, but only affirmatively; it will not unset any missing value.
There are 2-3 flags total (depending on whether or not the timestamps
feature has been enabled):
FLAG_INDENT
indents the message one level (four spaces);FLAG_NEWLINE
adds a trailing line break to the end;FLAG_TIMESTAMP
adds a[YYYY-MM-DD HH:MM:SS]
-style timestamp between the indentation and prefix;
Examples
use fyi_msg::{Msg, FLAG_INDENT, FLAG_NEWLINE}; let msg = Msg::plain("Indented message with trailing line.") .with_flags(FLAG_INDENT | FLAG_NEWLINE);
With Indent.
Indent the message using four spaces per indent
. To remove
indentation, pass 0
. Large values are capped at a maximum of 4
levels of indentation.
Examples
use fyi_msg::Msg; let msg = Msg::plain("Indented message.") .with_indent(1);
With Timestamp.
Disable, enable, and/or recalculate the timestamp prefix for the message.
This requires the timestamps
crate feature.
Examples
use fyi_msg::Msg; let msg = Msg::plain("Timestamped message.") .with_timestamp(true);
With Linebreak.
Add a trailing linebreak to the end of the message. This is either one or none; calling it multiple times won’t add more lines.
Without a linebreak, Msg::print
is analogous to print!()
,
whereas with a linebreak, it is more like println!()
. (The newline
isn’t limited to print contexts, but that’s mainly what it is for.)
Examples
use fyi_msg::Msg; let msg = Msg::plain("This has a trailing newline.") .with_newline(true);
With Prefix.
Set or reset the message prefix.
Examples
use fyi_msg::{Msg, MsgKind}; assert_eq!( Msg::plain("Hello world.").with_prefix(MsgKind::Success), Msg::new(MsgKind::Success, "Hello world.") );
#[must_use]pub fn with_custom_prefix<S>(self, prefix: S, color: u8) -> Self where
S: AsRef<str>,
[src]
#[must_use]pub fn with_custom_prefix<S>(self, prefix: S, color: u8) -> Self where
S: AsRef<str>,
[src]With Custom Prefix.
Set or reset the message with a user-defined prefix and color.
Examples
use fyi_msg::Msg; assert_eq!( Msg::plain("Hello world.").with_custom_prefix("Prefix", 4), Msg::custom("Prefix", 4, "Hello world.") );
With Message.
Set or reset the message portion of the message.
Examples
use fyi_msg::Msg; // A contrived example… let mut msg = Msg::plain("Should I say this?") .with_msg("No, this!");
With Suffix.
Set or reset the message suffix.
Unlike prefixes, there are no built-in suffixes, and as such, no assumptions or automatic formatting is applied. The value you set must include any spacing, delimiters, and formatting needed to have it look right. Generally you’ll want to at least have a leading space, otherwise you’ll get “messagesuffix” all glued together.
Examples
use fyi_msg::Msg; // A contrived example… let mut msg = Msg::plain("5,000 matching files were found.") .with_suffix(" (75%)");
Set Indentation.
This is the setter companion to the Msg::with_indent
builder
method. Refer to that documentation for more information.
Set Timestamp.
This is the setter companion to the Msg::with_timestamp
builder
method. Refer to that documentation for more information.
This requires the timestamps
crate feature.
Set Linebreak.
This is the setter companion to the Msg::with_newline
builder
method. Refer to that documentation for more information.
Set Prefix.
This is the setter companion to the Msg::with_prefix
builder
method. Refer to that documentation for more information.
Set Custom Prefix.
This is the setter companion to the Msg::with_custom_prefix
builder
method. Refer to that documentation for more information.
Set Message.
This is the setter companion to the Msg::with_msg
builder method.
Refer to that documentation for more information.
Set Suffix.
This is the setter companion to the Msg::with_suffix
builder
method. Refer to that documentation for more information.
Bytes Saved Suffix.
A lot of our own programs crunch data and report the savings as a suffix. This section just adds a quick helper for that.
Bytes Saved Suffix.
A lot of our own programs using this lib crunch data and report the savings as a suffix. This method just provides a quick way to generate that.
As Bytes.
Return the entire message as a byte slice. Alternatively, you could
dereference the struct or use Msg::as_ref
or Msg::borrow
.
As Str.
Return the entire message as a string slice. Alternatively, you could
use Msg::as_ref
or Msg::borrow
.
Into Vec.
Consume the message, returning an owned Vec<u8>
.
Into String.
Consume the message, returning an owned string.
Capped Width Slice.
This will return a byte string that should fit a given console width if
printed. This is subject to the usual disclaimers of “Unicode is
monstrously complicated…”, but it does its best, and will be more
accurate than simply chopping to the Msg::len
.
Only the user-defined message portion of the Msg
will be trimmed for
space. Prefixes, suffixes, the trailing newline, etc., are left
unchanged.
If the message cannot be made to fit, an empty byte string is returned.
This requires the fitted
crate feature.
Locked Print to STDOUT
.
This is equivalent to calling either print!()
or println()
depending on whether or not a trailing linebreak has been set.
In fact, Msg
does implement Display
, so you could do just that,
but this method avoids the allocation penalty.
Examples
use fyi_msg::Msg; Msg::plain("Hello world!").with_newline(true).print();
Locked Print to STDERR
.
This is equivalent to calling either eprint!()
or eprintln()
depending on whether or not a trailing linebreak has been set.
In fact, Msg
does implement Display
, so you could do just that,
but this method avoids the allocation penalty.
Examples
use fyi_msg::Msg; Msg::error("Oh no!").with_newline(true).eprint();
Print and Die.
This is a convenience method for printing a message to STDERR
and
terminating the thread with the provided exit code. Generally you’d
want to pass a non-zero value here.
Be careful calling this method in parallel contexts as it will only stop the current thread, not the entire program execution.
Examples
use fyi_msg::Msg; Msg::error("Oh no!").with_newline(true).die(1); unreachable!();
Prompt.
This produces a simple y/N input prompt, requiring the user type “Y” or
“N” to proceed. Positive values return true
, negative values return
false
. The default (if the user just hits
Note: the prompt normalizes the suffix and newline parts for display. If your message contains these parts, they will be ignored by the prompt action, but will be retained in the original struct should you wish to use it in some other manner later in your code.
Every example in the docs shows this in combination with the built-in
MsgKind::Confirm
prefix, but this can be called on any Msg
object. The main thing worth noting is the suffix portion is
overridden for display, so don’t bother putting anything there.
Example
use fyi_msg::{confirm, Msg, MsgKind}; // The manual way: if Msg::new(MsgKind::Confirm, "Do you like chickens?").prompt() { println!("That's great! They like you too!"); } // The macro way: if confirm!("Do you like chickens?") { println!("That's great! They like you too!"); }
Methods from Deref<Target = [u8]>
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());
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]); }
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]); }
Returns the last element of the slice, or None
if it is empty.
Examples
let v = [10, 40, 30]; assert_eq!(Some(&30), v.last()); let w: &[i32] = &[]; assert_eq!(None, w.last());
pub fn get<I>(&self, index: I) -> Option<&<I as SliceIndex<[T]>>::Output> where
I: SliceIndex<[T]>,
1.0.0[src]
pub fn get<I>(&self, index: I) -> Option<&<I as SliceIndex<[T]>>::Output> where
I: SliceIndex<[T]>,
1.0.0[src]Returns a reference to an element or subslice depending on the type of index.
- If given a position, returns a reference to the element at that
position or
None
if out of bounds. - If given a range, returns the subslice corresponding to that range,
or
None
if out of bounds.
Examples
let v = [10, 40, 30]; assert_eq!(Some(&40), v.get(1)); assert_eq!(Some(&[10, 40][..]), v.get(0..2)); assert_eq!(None, v.get(3)); assert_eq!(None, v.get(0..4));
pub unsafe fn get_unchecked<I>(
&self,
index: I
) -> &<I as SliceIndex<[T]>>::Output where
I: SliceIndex<[T]>,
1.0.0[src]
pub unsafe fn get_unchecked<I>(
&self,
index: I
) -> &<I as SliceIndex<[T]>>::Output where
I: SliceIndex<[T]>,
1.0.0[src]Returns a reference to an element or subslice, without doing bounds checking.
For a safe alternative see get
.
Safety
Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used.
Examples
let x = &[1, 2, 4]; unsafe { assert_eq!(x.get_unchecked(1), &2); }
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)); } }
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));
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);
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());
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());
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']);
🔬 This is a nightly-only experimental API. (slice_as_chunks
)
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
🔬 This is a nightly-only experimental API. (slice_as_chunks
)
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']);
🔬 This is a nightly-only experimental API. (slice_as_chunks
)
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']]);
🔬 This is a nightly-only experimental API. (array_chunks
)
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']);
🔬 This is a nightly-only experimental API. (array_windows
)
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());
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());
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']);
🔬 This is a nightly-only experimental API. (slice_group_by
)
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);
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, []); }
Returns an iterator over subslices separated by elements that match
pred
. The matched element is not contained in the subslices.
Examples
let slice = [10, 40, 33, 20]; let mut iter = slice.split(|num| num % 3 == 0); assert_eq!(iter.next().unwrap(), &[10, 40]); assert_eq!(iter.next().unwrap(), &[20]); assert!(iter.next().is_none());
If the first element is matched, an empty slice will be the first item returned by the iterator. Similarly, if the last element in the slice is matched, an empty slice will be the last item returned by the iterator:
let slice = [10, 40, 33]; let mut iter = slice.split(|num| num % 3 == 0); assert_eq!(iter.next().unwrap(), &[10, 40]); assert_eq!(iter.next().unwrap(), &[]); assert!(iter.next().is_none());
If two matched elements are directly adjacent, an empty slice will be present between them:
let slice = [10, 6, 33, 20]; let mut iter = slice.split(|num| num % 3 == 0); assert_eq!(iter.next().unwrap(), &[10]); assert_eq!(iter.next().unwrap(), &[]); assert_eq!(iter.next().unwrap(), &[20]); assert!(iter.next().is_none());
pub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F> where
F: FnMut(&T) -> bool,
1.51.0[src]
pub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F> where
F: FnMut(&T) -> bool,
1.51.0[src]Returns an iterator over subslices separated by elements that match
pred
. The matched element is contained in the end of the previous
subslice as a terminator.
Examples
let slice = [10, 40, 33, 20]; let mut iter = slice.split_inclusive(|num| num % 3 == 0); assert_eq!(iter.next().unwrap(), &[10, 40, 33]); assert_eq!(iter.next().unwrap(), &[20]); assert!(iter.next().is_none());
If the last element of the slice is matched, that element will be considered the terminator of the preceding slice. That slice will be the last item returned by the iterator.
let slice = [3, 10, 40, 33]; let mut iter = slice.split_inclusive(|num| num % 3 == 0); assert_eq!(iter.next().unwrap(), &[3]); assert_eq!(iter.next().unwrap(), &[10, 40, 33]); assert!(iter.next().is_none());
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);
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); }
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); }
Returns true
if the slice contains an element with the given value.
Examples
let v = [10, 40, 30]; assert!(v.contains(&30)); assert!(!v.contains(&50));
If you do not have a &T
, but some other value that you can compare
with one (for example, String
implements PartialEq<str>
), you can
use iter().any
:
let v = [String::from("hello"), String::from("world")]; // slice of `String` assert!(v.iter().any(|e| e == "hello")); // search with `&str` assert!(!v.iter().any(|e| e == "hi"));
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(&[]));
Returns true
if needle
is a suffix of the slice.
Examples
let v = [10, 40, 30]; assert!(v.ends_with(&[30])); assert!(v.ends_with(&[40, 30])); assert!(!v.ends_with(&[50])); assert!(!v.ends_with(&[50, 30]));
Always returns true
if needle
is an empty slice:
let v = &[10, 40, 30]; assert!(v.ends_with(&[])); let v: &[u8] = &[]; assert!(v.ends_with(&[]));
#[must_use = "returns the subslice without modifying the original"]pub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]> where
T: PartialEq<T>,
P: SlicePattern<Item = T> + ?Sized,
1.51.0[src]
#[must_use = "returns the subslice without modifying the original"]pub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]> where
T: PartialEq<T>,
P: SlicePattern<Item = T> + ?Sized,
1.51.0[src]Returns a subslice with the prefix removed.
If the slice starts with prefix
, returns the subslice after the prefix, wrapped in Some
.
If prefix
is empty, simply returns the original slice.
If the slice does not start with prefix
, returns None
.
Examples
let v = &[10, 40, 30]; assert_eq!(v.strip_prefix(&[10]), Some(&[40, 30][..])); assert_eq!(v.strip_prefix(&[10, 40]), Some(&[30][..])); assert_eq!(v.strip_prefix(&[50]), None); assert_eq!(v.strip_prefix(&[10, 50]), None); let prefix : &str = "he"; assert_eq!(b"hello".strip_prefix(prefix.as_bytes()), Some(b"llo".as_ref()));
#[must_use = "returns the subslice without modifying the original"]pub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]> where
T: PartialEq<T>,
P: SlicePattern<Item = T> + ?Sized,
1.51.0[src]
#[must_use = "returns the subslice without modifying the original"]pub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]> where
T: PartialEq<T>,
P: SlicePattern<Item = T> + ?Sized,
1.51.0[src]Returns a subslice with the suffix removed.
If the slice ends with suffix
, returns the subslice before the suffix, wrapped in Some
.
If suffix
is empty, simply returns the original slice.
If the slice does not end with suffix
, returns None
.
Examples
let v = &[10, 40, 30]; assert_eq!(v.strip_suffix(&[30]), Some(&[10, 40][..])); assert_eq!(v.strip_suffix(&[40, 30]), Some(&[10][..])); assert_eq!(v.strip_suffix(&[50]), None); assert_eq!(v.strip_suffix(&[50, 30]), None);
Binary searches this sorted slice for a given element.
If the value is found then Result::Ok
is returned, containing the
index of the matching element. If there are multiple matches, then any
one of the matches could be returned. 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:
let mut s = vec![0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55]; let num = 42; let idx = s.binary_search(&num).unwrap_or_else(|x| x); s.insert(idx, num); assert_eq!(s, [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 42, 55]);
Binary searches this sorted slice with a comparator function.
The comparator function should implement an order consistent
with the sort order of the underlying slice, returning an
order code that indicates whether its argument is Less
,
Equal
or Greater
the desired target.
If the value is found then Result::Ok
is returned, containing the
index of the matching element. If there are multiple matches, then any
one of the matches could be returned. 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, });
Binary searches this sorted slice with a key extraction function.
Assumes that the slice is sorted by the key, for instance with
sort_by_key
using the same key extraction function.
If the value is found then Result::Ok
is returned, containing the
index of the matching element. If there are multiple matches, then any
one of the matches could be returned. 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, });
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); }
🔬 This is a nightly-only experimental API. (is_sorted
)
new API
🔬 This is a nightly-only experimental API. (is_sorted
)
new API
Checks if the elements of this slice are sorted.
That is, for each element a
and its following element b
, a <= b
must hold. If the
slice yields exactly zero or one element, true
is returned.
Note that if Self::Item
is only PartialOrd
, but not Ord
, the above definition
implies that this function returns false
if any two consecutive items are not
comparable.
Examples
#![feature(is_sorted)] let empty: [i32; 0] = []; assert!([1, 2, 2, 9].is_sorted()); assert!(![1, 3, 2, 4].is_sorted()); assert!([0].is_sorted()); assert!(empty.is_sorted()); assert!(![0.0, 1.0, f32::NAN].is_sorted());
🔬 This is a nightly-only experimental API. (is_sorted
)
new API
🔬 This is a nightly-only experimental API. (is_sorted
)
new API
Checks if the elements of this slice are sorted using the given comparator function.
Instead of using PartialOrd::partial_cmp
, this function uses the given compare
function to determine the ordering of two elements. Apart from that, it’s equivalent to
is_sorted
; see its documentation for more information.
🔬 This is a nightly-only experimental API. (is_sorted
)
new API
🔬 This is a nightly-only experimental API. (is_sorted
)
new API
Checks if the elements of this slice are sorted using the given key extraction function.
Instead of comparing the slice’s elements directly, this function compares the keys of the
elements, as determined by f
. Apart from that, it’s equivalent to is_sorted
; see its
documentation for more information.
Examples
#![feature(is_sorted)] assert!(["c", "bb", "aaa"].is_sorted_by_key(|s| s.len())); assert!(![-2i32, -1, 0, 3].is_sorted_by_key(|n| n.abs()));
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)));
Checks if all bytes in this slice are within the ASCII range.
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.
🔬 This is a nightly-only experimental API. (inherent_ascii_escape
)
inherent_ascii_escape
)Returns an iterator that produces an escaped version of this slice, treating it as an ASCII string.
Examples
#![feature(inherent_ascii_escape)] let s = b"0\t\r\n'\"\\\x9d"; let escaped = s.escape_ascii().to_string(); assert_eq!(escaped, "0\\t\\r\\n\\'\\\"\\\\\\x9d");
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.
🔬 This is a nightly-only experimental API. (allocator_api
)
allocator_api
)Copies self
into a new Vec
with an allocator.
Examples
#![feature(allocator_api)] use std::alloc::System; let s = [10, 40, 30]; let x = s.to_vec_in(System); // Here, `s` and `x` can be modified independently.
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]);
Flattens a slice of T
into a single value Self::Output
, placing a
given separator between each.
Examples
assert_eq!(["hello", "world"].join(" "), "hello world"); assert_eq!([[1, 2], [3, 4]].join(&0), [1, 2, 0, 3, 4]); assert_eq!([[1, 2], [3, 4]].join(&[0, 0][..]), [1, 2, 0, 0, 3, 4]);
pub fn connect<Separator>(
&self,
sep: Separator
) -> <[T] as Join<Separator>>::Outputⓘ where
[T]: Join<Separator>,
1.0.0[src]👎 Deprecated since 1.3.0: renamed to join
pub fn connect<Separator>(
&self,
sep: Separator
) -> <[T] as Join<Separator>>::Outputⓘ where
[T]: Join<Separator>,
1.0.0[src]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]);
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
.
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 Msg
impl UnwindSafe for Msg
Blanket Implementations
Mutably borrows from an owned value. Read more