arrayvec/src/array_string.rs at master · nazar-pc/arrayvec · GitHub

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use std::borrow::{Borrow, BorrowMut};

use std::cmp;

use std::convert::TryFrom;

use std::fmt;

use std::hash::{Hash, Hasher};

use std::mem::MaybeUninit;

use std::ops::{Deref, DerefMut};

#[cfg(feature="std")]

use std::path::Path;

use std::ptr;

use std::slice;

use std::str;

use std::str::FromStr;

use std::str::Utf8Error;

use crate::CapacityError;

use crate::LenUint;

use crate::char::encode_utf8;

use crate::utils::MakeMaybeUninit;

#[cfg(feature="serde")]

use serde::{Serialize, Deserialize, Serializer, Deserializer};

/// A string with a fixed capacity.

///

/// The `ArrayString` is a string backed by a fixed size array. It keeps track

/// of its length, and is parameterized by `CAP` for the maximum capacity.

///

/// `CAP` is of type `usize` but is range limited to `u32::MAX` (or `u16` on 16-bit targets);

/// attempting to create larger arrayvecs with larger capacity will panic.

///

/// The string is a contiguous value that you can store directly on the stack

/// if needed.

#[derive(Copy)]

#[repr(C)]

pub struct ArrayString<const CAP: usize> {

// the `len` first elements of the array are initialized

len: LenUint,

xs: [MaybeUninit<u8>; CAP],

}

impl<const CAP: usize> Default for ArrayString<CAP>

{

/// Return an empty `ArrayString`

fn default() -> ArrayString<CAP> {

ArrayString::new()

}

impl<const CAP: usize> ArrayString<CAP>

{

/// Create a new empty `ArrayString`.

///

/// Capacity is inferred from the type parameter.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let mut string = ArrayString::<16>::new();

/// string.push_str("foo");

/// assert_eq!(&string[..], "foo");

/// assert_eq!(string.capacity(), 16);

/// ```

pub fn new() -> ArrayString<CAP> {

assert_capacity_limit!(CAP);

unsafe {

ArrayString { xs: MaybeUninit::uninit().assume_init(), len: 0 }

}

/// Create a new empty `ArrayString` (const fn).

///

/// Capacity is inferred from the type parameter.

///

/// ```

/// use arrayvec::ArrayString;

///

/// static ARRAY: ArrayString<1024> = ArrayString::new_const();

/// ```

pub const fn new_const() -> ArrayString<CAP> {

assert_capacity_limit_const!(CAP);

ArrayString { xs: MakeMaybeUninit::ARRAY, len: 0 }

}

/// Return the length of the string.

#[inline]

pub const fn len(&self) -> usize { self.len as usize }

/// Returns whether the string is empty.

#[inline]

pub const fn is_empty(&self) -> bool { self.len() == 0 }

/// Create a new `ArrayString` from a `str`.

///

/// Capacity is inferred from the type parameter.

///

/// **Errors** if the backing array is not large enough to fit the string.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let mut string = ArrayString::<3>::from("foo").unwrap();

/// assert_eq!(&string[..], "foo");

/// assert_eq!(string.len(), 3);

/// assert_eq!(string.capacity(), 3);

/// ```

pub fn from(s: &str) -> Result<Self, CapacityError<&str>> {

let mut arraystr = Self::new();

arraystr.try_push_str(s)?;

Ok(arraystr)

}

/// Create a new `ArrayString` from a byte string literal.

///

/// **Errors** if the byte string literal is not valid UTF-8.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let string = ArrayString::from_byte_string(b"hello world").unwrap();

/// ```

pub fn from_byte_string(b: &[u8; CAP]) -> Result<Self, Utf8Error> {

let len = str::from_utf8(b)?.len();

debug_assert_eq!(len, CAP);

let mut vec = Self::new();

unsafe {

(b as *const [u8; CAP] as *const [MaybeUninit<u8>; CAP])

.copy_to_nonoverlapping(&mut vec.xs as *mut [MaybeUninit<u8>; CAP], 1);

vec.set_len(CAP);

}

Ok(vec)

}

/// Create a new `ArrayString` value fully filled with ASCII NULL characters (`\0`). Useful

/// to be used as a buffer to collect external data or as a buffer for intermediate processing.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let string = ArrayString::<16>::zero_filled();

/// assert_eq!(string.len(), 16);

/// ```

#[inline]

pub fn zero_filled() -> Self {

assert_capacity_limit!(CAP);

// SAFETY: `assert_capacity_limit` asserts that `len` won't overflow and

// `zeroed` fully fills the array with nulls.

unsafe {

ArrayString {

xs: MaybeUninit::zeroed().assume_init(),

len: CAP as _

}

/// Return the capacity of the `ArrayString`.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let string = ArrayString::<3>::new();

/// assert_eq!(string.capacity(), 3);

/// ```

#[inline(always)]

pub const fn capacity(&self) -> usize { CAP }

/// Return if the `ArrayString` is completely filled.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let mut string = ArrayString::<1>::new();

/// assert!(!string.is_full());

/// string.push_str("A");

/// assert!(string.is_full());

/// ```

pub const fn is_full(&self) -> bool { self.len() == self.capacity() }

/// Returns the capacity left in the `ArrayString`.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let mut string = ArrayString::<3>::from("abc").unwrap();

/// string.pop();

/// assert_eq!(string.remaining_capacity(), 1);

/// ```

pub const fn remaining_capacity(&self) -> usize {

self.capacity() - self.len()

}

/// Adds the given char to the end of the string.

///

/// ***Panics*** if the backing array is not large enough to fit the additional char.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let mut string = ArrayString::<2>::new();

///

/// string.push('a');

/// string.push('b');

///

/// assert_eq!(&string[..], "ab");

/// ```

#[track_caller]

pub fn push(&mut self, c: char) {

self.try_push(c).unwrap();

}

/// Adds the given char to the end of the string.

///

/// Returns `Ok` if the push succeeds.

///

/// **Errors** if the backing array is not large enough to fit the additional char.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let mut string = ArrayString::<2>::new();

///

/// string.try_push('a').unwrap();

/// string.try_push('b').unwrap();

/// let overflow = string.try_push('c');

///

/// assert_eq!(&string[..], "ab");

/// assert_eq!(overflow.unwrap_err().element(), 'c');

/// ```

pub fn try_push(&mut self, c: char) -> Result<(), CapacityError<char>> {

let len = self.len();

unsafe {

let ptr = self.as_mut_ptr().add(len);

let remaining_cap = self.capacity() - len;

match encode_utf8(c, ptr, remaining_cap) {

Ok(n) => {

self.set_len(len + n);

Ok(())

}

Err(_) => Err(CapacityError::new(c)),

}

/// Adds the given string slice to the end of the string.

///

/// ***Panics*** if the backing array is not large enough to fit the string.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let mut string = ArrayString::<2>::new();

///

/// string.push_str("a");

/// string.push_str("d");

///

/// assert_eq!(&string[..], "ad");

/// ```

#[track_caller]

pub fn push_str(&mut self, s: &str) {

self.try_push_str(s).unwrap()

}

/// Adds the given string slice to the end of the string.

///

/// Returns `Ok` if the push succeeds.

///

/// **Errors** if the backing array is not large enough to fit the string.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let mut string = ArrayString::<2>::new();

///

/// string.try_push_str("a").unwrap();

/// let overflow1 = string.try_push_str("bc");

/// string.try_push_str("d").unwrap();

/// let overflow2 = string.try_push_str("ef");

///

/// assert_eq!(&string[..], "ad");

/// assert_eq!(overflow1.unwrap_err().element(), "bc");

/// assert_eq!(overflow2.unwrap_err().element(), "ef");

/// ```

pub fn try_push_str<'a>(&mut self, s: &'a str) -> Result<(), CapacityError<&'a str>> {

if s.len() > self.capacity() - self.len() {

return Err(CapacityError::new(s));

}

unsafe {

let dst = self.as_mut_ptr().add(self.len());

let src = s.as_ptr();

ptr::copy_nonoverlapping(src, dst, s.len());

let newl = self.len() + s.len();

self.set_len(newl);

}

Ok(())

}

/// Removes the last character from the string and returns it.

///

/// Returns `None` if this `ArrayString` is empty.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let mut s = ArrayString::<3>::from("foo").unwrap();

///

/// assert_eq!(s.pop(), Some('o'));

/// assert_eq!(s.pop(), Some('f'));

///

/// assert_eq!(s.pop(), None);

/// ```

pub fn pop(&mut self) -> Option<char> {

let ch = match self.chars().rev().next() {

Some(ch) => ch,

None => return None,

};

let new_len = self.len() - ch.len_utf8();

unsafe {

self.set_len(new_len);

}

Some(ch)

}

/// Shortens this `ArrayString` to the specified length.

///

/// If `new_len` is greater than the string’s current length, this has no

/// effect.

///

/// ***Panics*** if `new_len` does not lie on a `char` boundary.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let mut string = ArrayString::<6>::from("foobar").unwrap();

/// string.truncate(3);

/// assert_eq!(&string[..], "foo");

/// string.truncate(4);

/// assert_eq!(&string[..], "foo");

/// ```

pub fn truncate(&mut self, new_len: usize) {

if new_len <= self.len() {

assert!(self.is_char_boundary(new_len));

unsafe {

// In libstd truncate is called on the underlying vector,

// which in turns drops each element.

// As we know we don't have to worry about Drop,

// we can just set the length (a la clear.)

self.set_len(new_len);

}

/// Removes a `char` from this `ArrayString` at a byte position and returns it.

///

/// This is an `O(n)` operation, as it requires copying every element in the

/// array.

///

/// ***Panics*** if `idx` is larger than or equal to the `ArrayString`’s length,

/// or if it does not lie on a `char` boundary.

///

/// ```

/// use arrayvec::ArrayString;

///

/// let mut s = ArrayString::<3>::from("foo").unwrap();

///

/// assert_eq!(s.remove(0), 'f');

/// assert_eq!(s.remove(1), 'o');

/// assert_eq!(s.remove(0), 'o');

/// ```

pub fn remove(&mut self, idx: usize) -> char {

let ch = match self[idx..].chars().next() {

Some(ch) => ch,

None => panic!("cannot remove a char from the end of a string"),

};

let next = idx + ch.len_utf8();

let len = self.len();

let ptr = self.as_mut_ptr();

unsafe {

ptr::copy(

ptr.add(next),

ptr.add(idx),

len - next);

self.set_len(len - (next - idx));

}

/// Make the string empty.

pub fn clear(&mut self) {

unsafe {

self.set_len(0);

}

/// Set the strings’s length.

///

/// This function is `unsafe` because it changes the notion of the

/// number of “valid” bytes in the string. Use with care.

///

/// This method uses *debug assertions* to check the validity of `length`

/// and may use other debug assertions.

pub unsafe fn set_len(&mut self, length: usize) {

// type invariant that capacity always fits in LenUint

debug_assert!(length <= self.capacity());

self.len = length as LenUint;

}

/// Return a string slice of the whole `ArrayString`.

pub fn as_str(&self) -> &str {

self

}

/// Return a mutable string slice of the whole `ArrayString`.

pub fn as_mut_str(&mut self) -> &mut str {

self

}

/// Return a raw pointer to the string's buffer.

pub fn as_ptr(&self) -> *const u8 {

self.xs.as_ptr() as *const u8

}

/// Return a raw mutable pointer to the string's buffer.

pub fn as_mut_ptr(&mut self) -> *mut u8 {

self.xs.as_mut_ptr() as *mut u8

}

impl<const CAP: usize> Deref for ArrayString<CAP>

{

type Target = str;

#[inline]

fn deref(&self) -> &str {

unsafe {

let sl = slice::from_raw_parts(self.as_ptr(), self.len());

str::from_utf8_unchecked(sl)

}

impl<const CAP: usize> DerefMut for ArrayString<CAP>

{

#[inline]

fn deref_mut(&mut self) -> &mut str {

unsafe {

let len = self.len();

let sl = slice::from_raw_parts_mut(self.as_mut_ptr(), len);

str::from_utf8_unchecked_mut(sl)

}

impl<const CAP: usize> PartialEq for ArrayString<CAP>

{

fn eq(&self, rhs: &Self) -> bool {

**self == **rhs

}

impl<const CAP: usize> PartialEq<str> for ArrayString<CAP>

{

fn eq(&self, rhs: &str) -> bool {

&**self == rhs

}

impl<const CAP: usize> PartialEq<ArrayString<CAP>> for str

{

fn eq(&self, rhs: &ArrayString<CAP>) -> bool {

self == &**rhs

}

impl<const CAP: usize> Eq for ArrayString<CAP>

{ }

impl<const CAP: usize> Hash for ArrayString<CAP>

{

fn hash<H: Hasher>(&self, h: &mut H) {

(**self).hash(h)

}

impl<const CAP: usize> Borrow<str> for ArrayString<CAP>

{

fn borrow(&self) -> &str { self }

}

impl<const CAP: usize> BorrowMut<str> for ArrayString<CAP>

{

fn borrow_mut(&mut self) -> &mut str { self }

}

impl<const CAP: usize> AsRef<str> for ArrayString<CAP>

{

fn as_ref(&self) -> &str { self }

}

impl<const CAP: usize> fmt::Debug for ArrayString<CAP>

{

fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { (**self).fmt(f) }

}

#[cfg(feature="std")]

impl<const CAP: usize> AsRef<Path> for ArrayString<CAP> {

fn as_ref(&self) -> &Path {

self.as_str().as_ref()

}

impl<const CAP: usize> fmt::Display for ArrayString<CAP>

{

fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { (**self).fmt(f) }

}

/// `Write` appends written data to the end of the string.

impl<const CAP: usize> fmt::Write for ArrayString<CAP>

{

fn write_char(&mut self, c: char) -> fmt::Result {

self.try_push(c).map_err(|_| fmt::Error)

}

fn write_str(&mut self, s: &str) -> fmt::Result {

self.try_push_str(s).map_err(|_| fmt::Error)

}

impl<const CAP: usize> Clone for ArrayString<CAP>

{

fn clone(&self) -> ArrayString<CAP> {

*self

}

fn clone_from(&mut self, rhs: &Self) {

// guaranteed to fit due to types matching.

self.clear();

self.try_push_str(rhs).ok();

}

impl<const CAP: usize> PartialOrd for ArrayString<CAP>

{

fn partial_cmp(&self, rhs: &Self) -> Option<cmp::Ordering> {

(**self).partial_cmp(&**rhs)

}

fn lt(&self, rhs: &Self) -> bool { **self < **rhs }

fn le(&self, rhs: &Self) -> bool { **self <= **rhs }

fn gt(&self, rhs: &Self) -> bool { **self > **rhs }

fn ge(&self, rhs: &Self) -> bool { **self >= **rhs }

}

impl<const CAP: usize> PartialOrd<str> for ArrayString<CAP>

{

fn partial_cmp(&self, rhs: &str) -> Option<cmp::Ordering> {

(**self).partial_cmp(rhs)

}

fn lt(&self, rhs: &str) -> bool { &**self < rhs }

fn le(&self, rhs: &str) -> bool { &**self <= rhs }

fn gt(&self, rhs: &str) -> bool { &**self > rhs }

fn ge(&self, rhs: &str) -> bool { &**self >= rhs }

}

impl<const CAP: usize> PartialOrd<ArrayString<CAP>> for str

{

fn partial_cmp(&self, rhs: &ArrayString<CAP>) -> Option<cmp::Ordering> {

self.partial_cmp(&**rhs)

}

fn lt(&self, rhs: &ArrayString<CAP>) -> bool { self < &**rhs }

fn le(&self, rhs: &ArrayString<CAP>) -> bool { self <= &**rhs }

fn gt(&self, rhs: &ArrayString<CAP>) -> bool { self > &**rhs }

fn ge(&self, rhs: &ArrayString<CAP>) -> bool { self >= &**rhs }

}

impl<const CAP: usize> Ord for ArrayString<CAP>

{

fn cmp(&self, rhs: &Self) -> cmp::Ordering {

(**self).cmp(&**rhs)

}

impl<const CAP: usize> FromStr for ArrayString<CAP>

{

type Err = CapacityError;

fn from_str(s: &str) -> Result<Self, Self::Err> {

Self::from(s).map_err(CapacityError::simplify)

}

#[cfg(feature="serde")]

/// Requires crate feature `"serde"`

impl<const CAP: usize> Serialize for ArrayString<CAP>

{

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

where S: Serializer

{

serializer.serialize_str(&*self)

}

#[cfg(feature="serde")]

/// Requires crate feature `"serde"`

impl<'de, const CAP: usize> Deserialize<'de> for ArrayString<CAP>

{

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>

{

use serde::de::{self, Visitor};

use std::marker::PhantomData;

struct ArrayStringVisitor<const CAP: usize>(PhantomData<[u8; CAP]>);

impl<'de, const CAP: usize> Visitor<'de> for ArrayStringVisitor<CAP> {

type Value = ArrayString<CAP>;

fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {

write!(formatter, "a string no more than {} bytes long", CAP)

}

fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>

where E: de::Error,

{

ArrayString::from(v).map_err(|_| E::invalid_length(v.len(), &self))

}

fn visit_bytes<E>(self, v: &[u8]) -> Result<Self::Value, E>

where E: de::Error,

{

let s = str::from_utf8(v).map_err(|_| E::invalid_value(de::Unexpected::Bytes(v), &self))?;

ArrayString::from(s).map_err(|_| E::invalid_length(s.len(), &self))

}

deserializer.deserialize_str(ArrayStringVisitor(PhantomData))

}

#[cfg(feature = "borsh")]

/// Requires crate feature `"borsh"`

impl<const CAP: usize> borsh::BorshSerialize for ArrayString<CAP> {

fn serialize<W: borsh::io::Write>(&self, writer: &mut W) -> borsh::io::Result<()> {

<str as borsh::BorshSerialize>::serialize(&*self, writer)

}

#[cfg(feature = "borsh")]

/// Requires crate feature `"borsh"`

impl<const CAP: usize> borsh::BorshDeserialize for ArrayString<CAP> {

fn deserialize_reader<R: borsh::io::Read>(reader: &mut R) -> borsh::io::Result<Self> {

let len = <u32 as borsh::BorshDeserialize>::deserialize_reader(reader)? as usize;

if len > CAP {

return Err(borsh::io::Error::new(

borsh::io::ErrorKind::InvalidData,

format!("Expected a string no more than {} bytes long", CAP),

))

}

let mut buf = [0u8; CAP];

let buf = &mut buf[..len];

reader.read_exact(buf)?;

let s = str::from_utf8(&buf).map_err(|err| {

borsh::io::Error::new(borsh::io::ErrorKind::InvalidData, err.to_string())

})?;

Ok(Self::from(s).unwrap())

}

impl<'a, const CAP: usize> TryFrom<&'a str> for ArrayString<CAP>

{

type Error = CapacityError<&'a str>;

fn try_from(f: &'a str) -> Result<Self, Self::Error> {

let mut v = Self::new();

v.try_push_str(f)?;

Ok(v)

}

impl<'a, const CAP: usize> TryFrom<fmt::Arguments<'a>> for ArrayString<CAP>

{

type Error = CapacityError<fmt::Error>;

fn try_from(f: fmt::Arguments<'a>) -> Result<Self, Self::Error> {

use fmt::Write;

let mut v = Self::new();

v.write_fmt(f).map_err(|e| CapacityError::new(e))?;

Ok(v)

}

#[cfg(feature = "zeroize")]

/// "Best efforts" zeroing of the `ArrayString`'s buffer when the `zeroize` feature is enabled.

///

/// The length is set to 0, and the buffer is dropped and zeroized.

/// Cannot ensure that previous moves of the `ArrayString` did not leave values on the stack.

///

/// ```

/// use arrayvec::ArrayString;

/// use zeroize::Zeroize;

/// let mut string = ArrayString::<6>::from("foobar").unwrap();

/// string.zeroize();

/// assert_eq!(string.len(), 0);

/// unsafe { string.set_len(string.capacity()) };

/// assert_eq!(&*string, "\0\0\0\0\0\0");

/// ```

impl<const CAP: usize> zeroize::Zeroize for ArrayString<CAP> {

fn zeroize(&mut self) {

// There are no elements to drop

self.clear();

// Zeroize the backing array.

self.xs.zeroize();

}

arrayvec/src/array_string.rs at master · nazar-pc/arrayvec · GitHub

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