bluss
586 lines
16 KiB
Rust
586 lines
16 KiB
Rust
use std::borrow::Borrow;
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use std::cmp;
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use std::convert::TryFrom;
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use std::fmt;
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use std::hash::{Hash, Hasher};
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use std::mem::MaybeUninit;
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use std::ops::{Deref, DerefMut};
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use std::ptr;
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use std::slice;
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use std::str;
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use std::str::FromStr;
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use std::str::Utf8Error;
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use crate::CapacityError;
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use crate::char::encode_utf8;
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#[cfg(feature="serde")]
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use serde::{Serialize, Deserialize, Serializer, Deserializer};
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/// A string with a fixed capacity.
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///
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/// The `ArrayString` is a string backed by a fixed size array. It keeps track
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/// of its length.
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///
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/// The string is a contiguous value that you can store directly on the stack
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/// if needed.
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#[derive(Copy)]
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pub struct ArrayString<const CAP: usize> {
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// the `len` first elements of the array are initialized
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xs: [MaybeUninit<u8>; CAP],
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len: usize,
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}
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impl<const CAP: usize> Default for ArrayString<CAP>
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{
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/// Return an empty `ArrayString`
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fn default() -> ArrayString<CAP> {
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ArrayString::new()
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}
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}
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impl<const CAP: usize> ArrayString<CAP>
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{
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/// Create a new empty `ArrayString`.
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///
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/// Capacity is inferred from the type parameter.
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///
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/// ```
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/// use arrayvec::ArrayString;
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///
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/// let mut string = ArrayString::<16>::new();
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/// string.push_str("foo");
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/// assert_eq!(&string[..], "foo");
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/// assert_eq!(string.capacity(), 16);
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/// ```
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#[cfg(not(feature="unstable-const-fn"))]
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pub fn new() -> ArrayString<CAP> {
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unsafe {
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ArrayString { xs: MaybeUninit::uninit().assume_init(), len: 0 }
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}
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}
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#[cfg(feature="unstable-const-fn")]
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pub const fn new() -> ArrayString<CAP> {
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unsafe {
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ArrayString { xs: MaybeUninit::uninit().assume_init(), len: 0 }
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}
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}
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/// Return the length of the string.
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#[inline]
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pub fn len(&self) -> usize { self.len }
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/// Returns whether the string is empty.
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#[inline]
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pub fn is_empty(&self) -> bool { self.len() == 0 }
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/// Create a new `ArrayString` from a `str`.
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///
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/// Capacity is inferred from the type parameter.
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///
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/// **Errors** if the backing array is not large enough to fit the string.
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///
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/// ```
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/// use arrayvec::ArrayString;
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///
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/// let mut string = ArrayString::<3>::from("foo").unwrap();
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/// assert_eq!(&string[..], "foo");
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/// assert_eq!(string.len(), 3);
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/// assert_eq!(string.capacity(), 3);
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/// ```
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pub fn from(s: &str) -> Result<Self, CapacityError<&str>> {
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let mut arraystr = Self::new();
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arraystr.try_push_str(s)?;
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Ok(arraystr)
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}
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/// Create a new `ArrayString` from a byte string literal.
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///
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/// **Errors** if the byte string literal is not valid UTF-8.
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///
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/// ```
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/// use arrayvec::ArrayString;
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///
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/// let string = ArrayString::from_byte_string(b"hello world").unwrap();
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/// ```
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pub fn from_byte_string(b: &[u8; CAP]) -> Result<Self, Utf8Error> {
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let len = str::from_utf8(b)?.len();
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debug_assert_eq!(len, CAP);
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let mut vec = Self::new();
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unsafe {
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(b as *const [u8; CAP] as *const [MaybeUninit<u8>; CAP])
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.copy_to_nonoverlapping(&mut vec.xs as *mut [MaybeUninit<u8>; CAP], 1);
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vec.set_len(CAP);
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}
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Ok(vec)
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}
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/// Return the capacity of the `ArrayString`.
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///
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/// ```
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/// use arrayvec::ArrayString;
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///
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/// let string = ArrayString::<3>::new();
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/// assert_eq!(string.capacity(), 3);
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/// ```
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#[inline(always)]
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pub fn capacity(&self) -> usize { CAP }
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/// Return if the `ArrayString` is completely filled.
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///
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/// ```
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/// use arrayvec::ArrayString;
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///
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/// let mut string = ArrayString::<1>::new();
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/// assert!(!string.is_full());
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/// string.push_str("A");
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/// assert!(string.is_full());
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/// ```
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pub fn is_full(&self) -> bool { self.len() == self.capacity() }
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/// Adds the given char to the end of the string.
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///
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/// ***Panics*** if the backing array is not large enough to fit the additional char.
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///
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/// ```
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/// use arrayvec::ArrayString;
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///
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/// let mut string = ArrayString::<2>::new();
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///
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/// string.push('a');
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/// string.push('b');
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///
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/// assert_eq!(&string[..], "ab");
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/// ```
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pub fn push(&mut self, c: char) {
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self.try_push(c).unwrap();
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}
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/// Adds the given char to the end of the string.
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///
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/// Returns `Ok` if the push succeeds.
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///
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/// **Errors** if the backing array is not large enough to fit the additional char.
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///
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/// ```
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/// use arrayvec::ArrayString;
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///
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/// let mut string = ArrayString::<2>::new();
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///
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/// string.try_push('a').unwrap();
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/// string.try_push('b').unwrap();
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/// let overflow = string.try_push('c');
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///
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/// assert_eq!(&string[..], "ab");
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/// assert_eq!(overflow.unwrap_err().element(), 'c');
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/// ```
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pub fn try_push(&mut self, c: char) -> Result<(), CapacityError<char>> {
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let len = self.len();
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unsafe {
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let ptr = self.as_mut_ptr().add(len);
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let remaining_cap = self.capacity() - len;
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match encode_utf8(c, ptr, remaining_cap) {
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Ok(n) => {
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self.set_len(len + n);
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Ok(())
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}
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Err(_) => Err(CapacityError::new(c)),
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}
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}
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}
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/// Adds the given string slice to the end of the string.
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///
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/// ***Panics*** if the backing array is not large enough to fit the string.
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///
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/// ```
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/// use arrayvec::ArrayString;
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///
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/// let mut string = ArrayString::<2>::new();
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///
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/// string.push_str("a");
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/// string.push_str("d");
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///
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/// assert_eq!(&string[..], "ad");
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/// ```
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pub fn push_str(&mut self, s: &str) {
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self.try_push_str(s).unwrap()
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}
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/// Adds the given string slice to the end of the string.
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///
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/// Returns `Ok` if the push succeeds.
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///
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/// **Errors** if the backing array is not large enough to fit the string.
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///
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/// ```
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/// use arrayvec::ArrayString;
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///
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/// let mut string = ArrayString::<2>::new();
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///
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/// string.try_push_str("a").unwrap();
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/// let overflow1 = string.try_push_str("bc");
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/// string.try_push_str("d").unwrap();
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/// let overflow2 = string.try_push_str("ef");
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///
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/// assert_eq!(&string[..], "ad");
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/// assert_eq!(overflow1.unwrap_err().element(), "bc");
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/// assert_eq!(overflow2.unwrap_err().element(), "ef");
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/// ```
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pub fn try_push_str<'a>(&mut self, s: &'a str) -> Result<(), CapacityError<&'a str>> {
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if s.len() > self.capacity() - self.len() {
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return Err(CapacityError::new(s));
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}
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unsafe {
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let dst = self.as_mut_ptr().add(self.len());
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let src = s.as_ptr();
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ptr::copy_nonoverlapping(src, dst, s.len());
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let newl = self.len() + s.len();
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self.set_len(newl);
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}
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Ok(())
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}
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/// Removes the last character from the string and returns it.
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///
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/// Returns `None` if this `ArrayString` is empty.
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///
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/// ```
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/// use arrayvec::ArrayString;
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///
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/// let mut s = ArrayString::<3>::from("foo").unwrap();
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///
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/// assert_eq!(s.pop(), Some('o'));
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/// assert_eq!(s.pop(), Some('o'));
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/// assert_eq!(s.pop(), Some('f'));
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///
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/// assert_eq!(s.pop(), None);
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/// ```
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pub fn pop(&mut self) -> Option<char> {
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let ch = match self.chars().rev().next() {
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Some(ch) => ch,
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None => return None,
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};
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let new_len = self.len() - ch.len_utf8();
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unsafe {
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self.set_len(new_len);
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}
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Some(ch)
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}
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/// Shortens this `ArrayString` to the specified length.
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///
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/// If `new_len` is greater than the string’s current length, this has no
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/// effect.
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///
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/// ***Panics*** if `new_len` does not lie on a `char` boundary.
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///
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/// ```
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/// use arrayvec::ArrayString;
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///
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/// let mut string = ArrayString::<6>::from("foobar").unwrap();
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/// string.truncate(3);
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/// assert_eq!(&string[..], "foo");
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/// string.truncate(4);
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/// assert_eq!(&string[..], "foo");
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/// ```
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pub fn truncate(&mut self, new_len: usize) {
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if new_len <= self.len() {
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assert!(self.is_char_boundary(new_len));
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unsafe {
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// In libstd truncate is called on the underlying vector,
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// which in turns drops each element.
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// As we know we don't have to worry about Drop,
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// we can just set the length (a la clear.)
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self.set_len(new_len);
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}
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}
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}
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/// Removes a `char` from this `ArrayString` at a byte position and returns it.
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///
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/// This is an `O(n)` operation, as it requires copying every element in the
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/// array.
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///
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/// ***Panics*** if `idx` is larger than or equal to the `ArrayString`’s length,
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/// or if it does not lie on a `char` boundary.
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///
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/// ```
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/// use arrayvec::ArrayString;
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///
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/// let mut s = ArrayString::<3>::from("foo").unwrap();
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///
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/// assert_eq!(s.remove(0), 'f');
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/// assert_eq!(s.remove(1), 'o');
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/// assert_eq!(s.remove(0), 'o');
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/// ```
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pub fn remove(&mut self, idx: usize) -> char {
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let ch = match self[idx..].chars().next() {
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Some(ch) => ch,
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None => panic!("cannot remove a char from the end of a string"),
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};
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let next = idx + ch.len_utf8();
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let len = self.len();
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unsafe {
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ptr::copy(self.as_ptr().add(next),
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self.as_mut_ptr().add(idx),
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len - next);
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self.set_len(len - (next - idx));
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}
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ch
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}
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/// Make the string empty.
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pub fn clear(&mut self) {
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unsafe {
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self.set_len(0);
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}
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}
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/// Set the strings’s length.
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///
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/// This function is `unsafe` because it changes the notion of the
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/// number of “valid” bytes in the string. Use with care.
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///
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/// This method uses *debug assertions* to check the validity of `length`
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/// and may use other debug assertions.
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pub unsafe fn set_len(&mut self, length: usize) {
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debug_assert!(length <= self.capacity());
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self.len = length;
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}
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/// Return a string slice of the whole `ArrayString`.
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pub fn as_str(&self) -> &str {
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self
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}
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fn as_ptr(&self) -> *const u8 {
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self.xs.as_ptr() as *const u8
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}
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fn as_mut_ptr(&mut self) -> *mut u8 {
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self.xs.as_mut_ptr() as *mut u8
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}
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}
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impl<const CAP: usize> Deref for ArrayString<CAP>
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{
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type Target = str;
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#[inline]
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fn deref(&self) -> &str {
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unsafe {
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let sl = slice::from_raw_parts(self.as_ptr(), self.len);
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str::from_utf8_unchecked(sl)
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}
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}
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}
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impl<const CAP: usize> DerefMut for ArrayString<CAP>
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{
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#[inline]
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fn deref_mut(&mut self) -> &mut str {
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unsafe {
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let sl = slice::from_raw_parts_mut(self.as_mut_ptr(), self.len);
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str::from_utf8_unchecked_mut(sl)
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}
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}
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}
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impl<const CAP: usize> PartialEq for ArrayString<CAP>
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{
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fn eq(&self, rhs: &Self) -> bool {
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**self == **rhs
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}
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}
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impl<const CAP: usize> PartialEq<str> for ArrayString<CAP>
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{
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fn eq(&self, rhs: &str) -> bool {
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&**self == rhs
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}
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}
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impl<const CAP: usize> PartialEq<ArrayString<CAP>> for str
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{
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fn eq(&self, rhs: &ArrayString<CAP>) -> bool {
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self == &**rhs
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}
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}
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impl<const CAP: usize> Eq for ArrayString<CAP>
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{ }
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impl<const CAP: usize> Hash for ArrayString<CAP>
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{
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fn hash<H: Hasher>(&self, h: &mut H) {
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(**self).hash(h)
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}
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}
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impl<const CAP: usize> Borrow<str> for ArrayString<CAP>
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{
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fn borrow(&self) -> &str { self }
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}
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impl<const CAP: usize> AsRef<str> for ArrayString<CAP>
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{
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fn as_ref(&self) -> &str { self }
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}
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impl<const CAP: usize> fmt::Debug for ArrayString<CAP>
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{
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { (**self).fmt(f) }
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}
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impl<const CAP: usize> fmt::Display for ArrayString<CAP>
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{
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { (**self).fmt(f) }
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}
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/// `Write` appends written data to the end of the string.
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impl<const CAP: usize> fmt::Write for ArrayString<CAP>
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{
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fn write_char(&mut self, c: char) -> fmt::Result {
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self.try_push(c).map_err(|_| fmt::Error)
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}
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fn write_str(&mut self, s: &str) -> fmt::Result {
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self.try_push_str(s).map_err(|_| fmt::Error)
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}
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}
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impl<const CAP: usize> Clone for ArrayString<CAP>
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{
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fn clone(&self) -> ArrayString<CAP> {
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*self
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}
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fn clone_from(&mut self, rhs: &Self) {
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// guaranteed to fit due to types matching.
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self.clear();
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self.try_push_str(rhs).ok();
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}
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}
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impl<const CAP: usize> PartialOrd for ArrayString<CAP>
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{
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fn partial_cmp(&self, rhs: &Self) -> Option<cmp::Ordering> {
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(**self).partial_cmp(&**rhs)
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}
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fn lt(&self, rhs: &Self) -> bool { **self < **rhs }
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fn le(&self, rhs: &Self) -> bool { **self <= **rhs }
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fn gt(&self, rhs: &Self) -> bool { **self > **rhs }
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fn ge(&self, rhs: &Self) -> bool { **self >= **rhs }
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}
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impl<const CAP: usize> PartialOrd<str> for ArrayString<CAP>
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{
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fn partial_cmp(&self, rhs: &str) -> Option<cmp::Ordering> {
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(**self).partial_cmp(rhs)
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}
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fn lt(&self, rhs: &str) -> bool { &**self < rhs }
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fn le(&self, rhs: &str) -> bool { &**self <= rhs }
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fn gt(&self, rhs: &str) -> bool { &**self > rhs }
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fn ge(&self, rhs: &str) -> bool { &**self >= rhs }
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}
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impl<const CAP: usize> PartialOrd<ArrayString<CAP>> for str
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{
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fn partial_cmp(&self, rhs: &ArrayString<CAP>) -> Option<cmp::Ordering> {
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self.partial_cmp(&**rhs)
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}
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fn lt(&self, rhs: &ArrayString<CAP>) -> bool { self < &**rhs }
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fn le(&self, rhs: &ArrayString<CAP>) -> bool { self <= &**rhs }
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fn gt(&self, rhs: &ArrayString<CAP>) -> bool { self > &**rhs }
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fn ge(&self, rhs: &ArrayString<CAP>) -> bool { self >= &**rhs }
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}
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impl<const CAP: usize> Ord for ArrayString<CAP>
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{
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fn cmp(&self, rhs: &Self) -> cmp::Ordering {
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(**self).cmp(&**rhs)
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}
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}
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impl<const CAP: usize> FromStr for ArrayString<CAP>
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{
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type Err = CapacityError;
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fn from_str(s: &str) -> Result<Self, Self::Err> {
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Self::from(s).map_err(CapacityError::simplify)
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}
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}
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#[cfg(feature="serde")]
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/// Requires crate feature `"serde"`
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impl<const CAP: usize> Serialize for ArrayString<CAP>
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{
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fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
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where S: Serializer
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{
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serializer.serialize_str(&*self)
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}
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}
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#[cfg(feature="serde")]
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/// 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)
|
||
}
|
||
}
|