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use std::borrow::Borrow;
use std::cmp;
use std::convert::TryFrom;
use std::fmt;
use std::hash::{Hash, Hasher};
use std::mem::MaybeUninit;
use std::ops::{Deref, DerefMut};
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`; 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)]
pub struct ArrayString<const CAP: usize> {
// the `len` first elements of the array are initialized
xs: [MaybeUninit<u8>; CAP],
len: LenUint,
}
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");
/// ```
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");
/// ```
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('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();
unsafe {
ptr::copy(self.as_ptr().add(next),
self.as_mut_ptr().add(idx),
len - next);
self.set_len(len - (next - idx));
}
ch
}
/// 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
}
fn as_ptr(&self) -> *const u8 {
self.xs.as_ptr() as *const u8
}
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> 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) }
}
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))
}
}
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)
}
}