Vendor dependencies for 0.3.0 release

vendor/arrayvec/src/array_string.rs

@@ -0,0 +1,716 @@
+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`; 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('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));
+        }
+        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
+    }
+
+    /// 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();
+    }
+}

vendor/arrayvec/src/arrayvec_impl.rs

@@ -0,0 +1,87 @@
+use std::ptr;
+use std::slice;
+
+use crate::CapacityError;
+
+/// Implements basic arrayvec methods - based on a few required methods
+/// for length and element access.
+pub(crate) trait ArrayVecImpl {
+    type Item;
+    const CAPACITY: usize;
+
+    fn len(&self) -> usize;
+
+    unsafe fn set_len(&mut self, new_len: usize);
+
+    /// Return a slice containing all elements of the vector.
+    fn as_slice(&self) -> &[Self::Item] {
+        let len = self.len();
+        unsafe {
+            slice::from_raw_parts(self.as_ptr(), len)
+        }
+    }
+
+    /// Return a mutable slice containing all elements of the vector.
+    fn as_mut_slice(&mut self) -> &mut [Self::Item] {
+        let len = self.len();
+        unsafe {
+            std::slice::from_raw_parts_mut(self.as_mut_ptr(), len)
+        }
+    }
+
+    /// Return a raw pointer to the vector's buffer.
+    fn as_ptr(&self) -> *const Self::Item;
+
+    /// Return a raw mutable pointer to the vector's buffer.
+    fn as_mut_ptr(&mut self) -> *mut Self::Item;
+
+    #[track_caller]
+    fn push(&mut self, element: Self::Item) {
+        self.try_push(element).unwrap()
+    }
+
+    fn try_push(&mut self, element: Self::Item) -> Result<(), CapacityError<Self::Item>> {
+        if self.len() < Self::CAPACITY {
+            unsafe {
+                self.push_unchecked(element);
+            }
+            Ok(())
+        } else {
+            Err(CapacityError::new(element))
+        }
+    }
+
+    unsafe fn push_unchecked(&mut self, element: Self::Item) {
+        let len = self.len();
+        debug_assert!(len < Self::CAPACITY);
+        ptr::write(self.as_mut_ptr().add(len), element);
+        self.set_len(len + 1);
+    }
+
+    fn pop(&mut self) -> Option<Self::Item> {
+        if self.len() == 0 {
+            return None;
+        }
+        unsafe {
+            let new_len = self.len() - 1;
+            self.set_len(new_len);
+            Some(ptr::read(self.as_ptr().add(new_len)))
+        }
+    }
+
+    fn clear(&mut self) {
+        self.truncate(0)
+    }
+
+    fn truncate(&mut self, new_len: usize) {
+        unsafe {
+            let len = self.len();
+            if new_len < len {
+                self.set_len(new_len);
+                let tail = slice::from_raw_parts_mut(self.as_mut_ptr().add(new_len), len - new_len);
+                ptr::drop_in_place(tail);
+            }
+        }
+    }
+}
+

vendor/arrayvec/src/char.rs

@@ -0,0 +1,92 @@
+// Copyright 2012-2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+//
+// Original authors: alexchrichton, bluss
+
+// UTF-8 ranges and tags for encoding characters
+const TAG_CONT: u8    = 0b1000_0000;
+const TAG_TWO_B: u8   = 0b1100_0000;
+const TAG_THREE_B: u8 = 0b1110_0000;
+const TAG_FOUR_B: u8  = 0b1111_0000;
+const MAX_ONE_B: u32   =     0x80;
+const MAX_TWO_B: u32   =    0x800;
+const MAX_THREE_B: u32 =  0x10000;
+
+/// Placeholder
+pub struct EncodeUtf8Error;
+
+/// Encode a char into buf using UTF-8.
+///
+/// On success, return the byte length of the encoding (1, 2, 3 or 4).<br>
+/// On error, return `EncodeUtf8Error` if the buffer was too short for the char.
+///
+/// Safety: `ptr` must be writable for `len` bytes.
+#[inline]
+pub unsafe fn encode_utf8(ch: char, ptr: *mut u8, len: usize) -> Result<usize, EncodeUtf8Error>
+{
+    let code = ch as u32;
+    if code < MAX_ONE_B && len >= 1 {
+        ptr.add(0).write(code as u8);
+        return Ok(1);
+    } else if code < MAX_TWO_B && len >= 2 {
+        ptr.add(0).write((code >> 6 & 0x1F) as u8 | TAG_TWO_B);
+        ptr.add(1).write((code & 0x3F) as u8 | TAG_CONT);
+        return Ok(2);
+    } else if code < MAX_THREE_B && len >= 3 {
+        ptr.add(0).write((code >> 12 & 0x0F) as u8 | TAG_THREE_B);
+        ptr.add(1).write((code >>  6 & 0x3F) as u8 | TAG_CONT);
+        ptr.add(2).write((code & 0x3F) as u8 | TAG_CONT);
+        return Ok(3);
+    } else if len >= 4 {
+        ptr.add(0).write((code >> 18 & 0x07) as u8 | TAG_FOUR_B);
+        ptr.add(1).write((code >> 12 & 0x3F) as u8 | TAG_CONT);
+        ptr.add(2).write((code >>  6 & 0x3F) as u8 | TAG_CONT);
+        ptr.add(3).write((code & 0x3F) as u8 | TAG_CONT);
+        return Ok(4);
+    };
+    Err(EncodeUtf8Error)
+}
+
+
+#[test]
+#[cfg_attr(miri, ignore)] // Miri is too slow
+fn test_encode_utf8() {
+    // Test that all codepoints are encoded correctly
+    let mut data = [0u8; 16];
+    for codepoint in 0..=(std::char::MAX as u32) {
+        if let Some(ch) = std::char::from_u32(codepoint) {
+            for elt in &mut data { *elt = 0; }
+            let ptr = data.as_mut_ptr();
+            let len = data.len();
+            unsafe {
+                let res = encode_utf8(ch, ptr, len).ok().unwrap();
+                assert_eq!(res, ch.len_utf8());
+            }
+            let string = std::str::from_utf8(&data).unwrap();
+            assert_eq!(string.chars().next(), Some(ch));
+        }
+    }
+}
+
+#[test]
+fn test_encode_utf8_oob() {
+    // test that we report oob if the buffer is too short
+    let mut data = [0u8; 16];
+    let chars = ['a', 'α', '<27>', '𐍈'];
+    for (len, &ch) in (1..=4).zip(&chars) {
+        assert_eq!(len, ch.len_utf8(), "Len of ch={}", ch);
+        let ptr = data.as_mut_ptr();
+        unsafe {
+            assert!(matches::matches!(encode_utf8(ch, ptr, len - 1), Err(_)));
+            assert!(matches::matches!(encode_utf8(ch, ptr, len), Ok(_)));
+        }
+    }
+}
+

vendor/arrayvec/src/errors.rs

@@ -0,0 +1,49 @@
+use std::fmt;
+#[cfg(feature="std")]
+use std::any::Any;
+#[cfg(feature="std")]
+use std::error::Error;
+
+/// Error value indicating insufficient capacity
+#[derive(Clone, Copy, Eq, Ord, PartialEq, PartialOrd)]
+pub struct CapacityError<T = ()> {
+    element: T,
+}
+
+impl<T> CapacityError<T> {
+    /// Create a new `CapacityError` from `element`.
+    pub const fn new(element: T) -> CapacityError<T> {
+        CapacityError {
+            element: element,
+        }
+    }
+
+    /// Extract the overflowing element
+    pub fn element(self) -> T {
+        self.element
+    }
+
+    /// Convert into a `CapacityError` that does not carry an element.
+    pub fn simplify(self) -> CapacityError {
+        CapacityError { element: () }
+    }
+}
+
+const CAPERROR: &'static str = "insufficient capacity";
+
+#[cfg(feature="std")]
+/// Requires `features="std"`.
+impl<T: Any> Error for CapacityError<T> {}
+
+impl<T> fmt::Display for CapacityError<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", CAPERROR)
+    }
+}
+
+impl<T> fmt::Debug for CapacityError<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}: {}", "CapacityError", CAPERROR)
+    }
+}
+

vendor/arrayvec/src/lib.rs

@@ -0,0 +1,63 @@
+//! **arrayvec** provides the types [`ArrayVec`] and [`ArrayString`]: 
+//! array-backed vector and string types, which store their contents inline.
+//!
+//! The arrayvec package has the following cargo features:
+//!
+//! - `std`
+//!   - Optional, enabled by default
+//!   - Use libstd; disable to use `no_std` instead.
+//!
+//! - `serde`
+//!   - Optional
+//!   - Enable serialization for ArrayVec and ArrayString using serde 1.x
+//!
+//! - `zeroize`
+//!   - Optional
+//!   - Implement `Zeroize` for ArrayVec and ArrayString
+//!
+//! ## Rust Version
+//!
+//! This version of arrayvec requires Rust 1.51 or later.
+//!
+#![doc(html_root_url="https://docs.rs/arrayvec/0.7/")]
+#![cfg_attr(not(feature="std"), no_std)]
+
+#[cfg(feature="serde")]
+extern crate serde;
+
+#[cfg(not(feature="std"))]
+extern crate core as std;
+
+pub(crate) type LenUint = u32;
+
+macro_rules! assert_capacity_limit {
+    ($cap:expr) => {
+        if std::mem::size_of::<usize>() > std::mem::size_of::<LenUint>() {
+            if $cap > LenUint::MAX as usize {
+                panic!("ArrayVec: largest supported capacity is u32::MAX")
+            }
+        }
+    }
+}
+
+macro_rules! assert_capacity_limit_const {
+    ($cap:expr) => {
+        if std::mem::size_of::<usize>() > std::mem::size_of::<LenUint>() {
+            if $cap > LenUint::MAX as usize {
+                [/*ArrayVec: largest supported capacity is u32::MAX*/][$cap]
+            }
+        }
+    }
+}
+
+mod arrayvec_impl;
+mod arrayvec;
+mod array_string;
+mod char;
+mod errors;
+mod utils;
+
+pub use crate::array_string::ArrayString;
+pub use crate::errors::CapacityError;
+
+pub use crate::arrayvec::{ArrayVec, IntoIter, Drain};

vendor/arrayvec/src/utils.rs

@@ -0,0 +1,11 @@
+use std::marker::PhantomData;
+use std::mem::MaybeUninit;
+
+pub(crate) struct MakeMaybeUninit<T, const N: usize>(PhantomData<fn() -> T>);
+
+impl<T, const N: usize> MakeMaybeUninit<T, N> {
+    pub(crate) const VALUE: MaybeUninit<T> = MaybeUninit::uninit();
+
+    pub(crate) const ARRAY: [MaybeUninit<T>; N] = [Self::VALUE; N];
+}
+