Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2141 insertions, 0 deletions

diff --git a/third_party/rust/bumpalo/src/collections/string.rs b/third_party/rust/bumpalo/src/collections/string.rs
new file mode 100644
index 0000000000..ffd1db92de
--- /dev/null
+++ b/third_party/rust/bumpalo/src/collections/string.rs
@@ -0,0 +1,2141 @@
+// Copyright 2014 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.
+
+//! A UTF-8 encoded, growable string.
+//!
+//! This module contains the [`String`] type and several error types that may
+//! result from working with [`String`]s.
+//!
+//! This module is a fork of the [`std::string`] module, that uses a bump allocator.
+//!
+//! [`std::string`]: https://doc.rust-lang.org/std/string/index.html
+//!
+//! # Examples
+//!
+//! You can create a new [`String`] from a string literal with [`String::from_str_in`]:
+//!
+//! ```
+//! use bumpalo::{Bump, collections::String};
+//!
+//! let b = Bump::new();
+//!
+//! let s = String::from_str_in("world", &b);
+//! ```
+//!
+//! [`String`]: struct.String.html
+//! [`String::from_str_in`]: struct.String.html#method.from_str_in
+//!
+//! If you have a vector of valid UTF-8 bytes, you can make a [`String`] out of
+//! it. You can do the reverse too.
+//!
+//! ```
+//! use bumpalo::{Bump, collections::String};
+//!
+//! let b = Bump::new();
+//!
+//! let sparkle_heart = bumpalo::vec![in &b; 240, 159, 146, 150];
+//!
+//! // We know these bytes are valid, so we'll use `unwrap()`.
+//! let sparkle_heart = String::from_utf8(sparkle_heart).unwrap();
+//!
+//! assert_eq!("💖", sparkle_heart);
+//!
+//! let bytes = sparkle_heart.into_bytes();
+//!
+//! assert_eq!(bytes, [240, 159, 146, 150]);
+//! ```
+
+use crate::collections::str::lossy;
+use crate::collections::vec::Vec;
+use crate::Bump;
+use core::borrow::{Borrow, BorrowMut};
+use core::char::decode_utf16;
+use core::fmt;
+use core::hash;
+use core::iter::FusedIterator;
+use core::mem;
+use core::ops::Bound::{Excluded, Included, Unbounded};
+use core::ops::{self, Add, AddAssign, Index, IndexMut, RangeBounds};
+use core::ptr;
+use core::str::{self, Chars, Utf8Error};
+use core_alloc::borrow::Cow;
+
+/// Like the [`format!`] macro, but for creating [`bumpalo::collections::String`]s.
+///
+/// [`format!`]: https://doc.rust-lang.org/std/macro.format.html
+/// [`bumpalo::collections::String`]: collections/string/struct.String.html
+///
+/// # Examples
+///
+/// ```
+/// use bumpalo::Bump;
+///
+/// let b = Bump::new();
+///
+/// let who = "World";
+/// let s = bumpalo::format!(in &b, "Hello, {}!", who);
+/// assert_eq!(s, "Hello, World!")
+/// ```
+#[macro_export]
+macro_rules! format {
+    ( in $bump:expr, $fmt:expr, $($args:expr),* ) => {{
+        use $crate::core_alloc::fmt::Write;
+        let bump = $bump;
+        let mut s = $crate::collections::String::new_in(bump);
+        let _ = write!(&mut s, $fmt, $($args),*);
+        s
+    }};
+
+    ( in $bump:expr, $fmt:expr, $($args:expr,)* ) => {
+        $crate::format!(in $bump, $fmt, $($args),*)
+    };
+}
+
+/// A UTF-8 encoded, growable string.
+///
+/// The `String` type is the most common string type that has ownership over the
+/// contents of the string. It has a close relationship with its borrowed
+/// counterpart, the primitive [`str`].
+///
+/// [`str`]: https://doc.rust-lang.org/std/primitive.str.html
+///
+/// # Examples
+///
+/// You can create a `String` from a literal string with [`String::from_str_in`]:
+///
+/// ```
+/// use bumpalo::{Bump, collections::String};
+///
+/// let b = Bump::new();
+///
+/// let hello = String::from_str_in("Hello, world!", &b);
+/// ```
+///
+/// You can append a [`char`] to a `String` with the [`push`] method, and
+/// append a [`&str`] with the [`push_str`] method:
+///
+/// ```
+/// use bumpalo::{Bump, collections::String};
+///
+/// let b = Bump::new();
+///
+/// let mut hello = String::from_str_in("Hello, ", &b);
+///
+/// hello.push('w');
+/// hello.push_str("orld!");
+/// ```
+///
+/// [`char`]: https://doc.rust-lang.org/std/primitive.char.html
+/// [`push`]: #method.push
+/// [`push_str`]: #method.push_str
+///
+/// If you have a vector of UTF-8 bytes, you can create a `String` from it with
+/// the [`from_utf8`] method:
+///
+/// ```
+/// use bumpalo::{Bump, collections::String};
+///
+/// let b = Bump::new();
+///
+/// // some bytes, in a vector
+/// let sparkle_heart = bumpalo::vec![in &b; 240, 159, 146, 150];
+///
+/// // We know these bytes are valid, so we'll use `unwrap()`.
+/// let sparkle_heart = String::from_utf8(sparkle_heart).unwrap();
+///
+/// assert_eq!("💖", sparkle_heart);
+/// ```
+///
+/// [`from_utf8`]: #method.from_utf8
+///
+/// # Deref
+///
+/// `String`s implement <code>[`Deref`]<Target = [`str`]></code>, and so inherit all of [`str`]'s
+/// methods. In addition, this means that you can pass a `String` to a
+/// function which takes a [`&str`] by using an ampersand (`&`):
+///
+/// ```
+/// use bumpalo::{Bump, collections::String};
+///
+/// let b = Bump::new();
+///
+/// fn takes_str(s: &str) { }
+///
+/// let s = String::from_str_in("Hello", &b);
+///
+/// takes_str(&s);
+/// ```
+///
+/// This will create a [`&str`] from the `String` and pass it in. This
+/// conversion is very inexpensive, and so generally, functions will accept
+/// [`&str`]s as arguments unless they need a `String` for some specific
+/// reason.
+///
+/// In certain cases Rust doesn't have enough information to make this
+/// conversion, known as [`Deref`] coercion. In the following example a string
+/// slice [`&'a str`][`&str`] implements the trait `TraitExample`, and the function
+/// `example_func` takes anything that implements the trait. In this case Rust
+/// would need to make two implicit conversions, which Rust doesn't have the
+/// means to do. For that reason, the following example will not compile.
+///
+/// ```compile_fail,E0277
+/// use bumpalo::{Bump, collections::String};
+///
+/// trait TraitExample {}
+///
+/// impl<'a> TraitExample for &'a str {}
+///
+/// fn example_func<A: TraitExample>(example_arg: A) {}
+///
+/// let b = Bump::new();
+/// let example_string = String::from_str_in("example_string", &b);
+/// example_func(&example_string);
+/// ```
+///
+/// There are two options that would work instead. The first would be to
+/// change the line `example_func(&example_string);` to
+/// `example_func(example_string.as_str());`, using the method [`as_str()`]
+/// to explicitly extract the string slice containing the string. The second
+/// way changes `example_func(&example_string);` to
+/// `example_func(&*example_string);`. In this case we are dereferencing a
+/// `String` to a [`str`][`&str`], then referencing the [`str`][`&str`] back to
+/// [`&str`]. The second way is more idiomatic, however both work to do the
+/// conversion explicitly rather than relying on the implicit conversion.
+///
+/// # Representation
+///
+/// A `String` is made up of three components: a pointer to some bytes, a
+/// length, and a capacity. The pointer points to an internal buffer `String`
+/// uses to store its data. The length is the number of bytes currently stored
+/// in the buffer, and the capacity is the size of the buffer in bytes. As such,
+/// the length will always be less than or equal to the capacity.
+///
+/// This buffer is always stored on the heap.
+///
+/// You can look at these with the [`as_ptr`], [`len`], and [`capacity`]
+/// methods:
+///
+/// ```
+/// use bumpalo::{Bump, collections::String};
+/// use std::mem;
+///
+/// let b = Bump::new();
+///
+/// let mut story = String::from_str_in("Once upon a time...", &b);
+///
+/// let ptr = story.as_mut_ptr();
+/// let len = story.len();
+/// let capacity = story.capacity();
+///
+/// // story has nineteen bytes
+/// assert_eq!(19, len);
+///
+/// // Now that we have our parts, we throw the story away.
+/// mem::forget(story);
+///
+/// // We can re-build a String out of ptr, len, and capacity. This is all
+/// // unsafe because we are responsible for making sure the components are
+/// // valid:
+/// let s = unsafe { String::from_raw_parts_in(ptr, len, capacity, &b) } ;
+///
+/// assert_eq!(String::from_str_in("Once upon a time...", &b), s);
+/// ```
+///
+/// [`as_ptr`]: https://doc.rust-lang.org/std/primitive.str.html#method.as_ptr
+/// [`len`]: #method.len
+/// [`capacity`]: #method.capacity
+///
+/// If a `String` has enough capacity, adding elements to it will not
+/// re-allocate. For example, consider this program:
+///
+/// ```
+/// use bumpalo::{Bump, collections::String};
+///
+/// let b = Bump::new();
+///
+/// let mut s = String::new_in(&b);
+///
+/// println!("{}", s.capacity());
+///
+/// for _ in 0..5 {
+///     s.push_str("hello");
+///     println!("{}", s.capacity());
+/// }
+/// ```
+///
+/// This will output the following:
+///
+/// ```text
+/// 0
+/// 5
+/// 10
+/// 20
+/// 20
+/// 40
+/// ```
+///
+/// At first, we have no memory allocated at all, but as we append to the
+/// string, it increases its capacity appropriately. If we instead use the
+/// [`with_capacity_in`] method to allocate the correct capacity initially:
+///
+/// ```
+/// use bumpalo::{Bump, collections::String};
+///
+/// let b = Bump::new();
+///
+/// let mut s = String::with_capacity_in(25, &b);
+///
+/// println!("{}", s.capacity());
+///
+/// for _ in 0..5 {
+///     s.push_str("hello");
+///     println!("{}", s.capacity());
+/// }
+/// ```
+///
+/// [`with_capacity_in`]: #method.with_capacity_in
+///
+/// We end up with a different output:
+///
+/// ```text
+/// 25
+/// 25
+/// 25
+/// 25
+/// 25
+/// 25
+/// ```
+///
+/// Here, there's no need to allocate more memory inside the loop.
+///
+/// [`&str`]: https://doc.rust-lang.org/std/primitive.str.html
+/// [`Deref`]: https://doc.rust-lang.org/std/ops/trait.Deref.html
+/// [`as_str()`]: struct.String.html#method.as_str
+#[derive(PartialOrd, Eq, Ord)]
+pub struct String<'bump> {
+    vec: Vec<'bump, u8>,
+}
+
+/// A possible error value when converting a `String` from a UTF-8 byte vector.
+///
+/// This type is the error type for the [`from_utf8`] method on [`String`]. It
+/// is designed in such a way to carefully avoid reallocations: the
+/// [`into_bytes`] method will give back the byte vector that was used in the
+/// conversion attempt.
+///
+/// [`from_utf8`]: struct.String.html#method.from_utf8
+/// [`String`]: struct.String.html
+/// [`into_bytes`]: struct.FromUtf8Error.html#method.into_bytes
+///
+/// The [`Utf8Error`] type provided by [`std::str`] represents an error that may
+/// occur when converting a slice of [`u8`]s to a [`&str`]. In this sense, it's
+/// an analogue to `FromUtf8Error`, and you can get one from a `FromUtf8Error`
+/// through the [`utf8_error`] method.
+///
+/// [`Utf8Error`]: https://doc.rust-lang.org/std/str/struct.Utf8Error.html
+/// [`std::str`]: https://doc.rust-lang.org/std/str/index.html
+/// [`u8`]: https://doc.rust-lang.org/std/primitive.u8.html
+/// [`&str`]: https://doc.rust-lang.org/std/primitive.str.html
+/// [`utf8_error`]: #method.utf8_error
+///
+/// # Examples
+///
+/// Basic usage:
+///
+/// ```
+/// use bumpalo::{Bump, collections::String};
+///
+/// let b = Bump::new();
+///
+/// // some invalid bytes, in a vector
+/// let bytes = bumpalo::vec![in &b; 0, 159];
+///
+/// let value = String::from_utf8(bytes);
+///
+/// assert!(value.is_err());
+/// assert_eq!(bumpalo::vec![in &b; 0, 159], value.unwrap_err().into_bytes());
+/// ```
+#[derive(Debug)]
+pub struct FromUtf8Error<'bump> {
+    bytes: Vec<'bump, u8>,
+    error: Utf8Error,
+}
+
+/// A possible error value when converting a `String` from a UTF-16 byte slice.
+///
+/// This type is the error type for the [`from_utf16_in`] method on [`String`].
+///
+/// [`from_utf16_in`]: struct.String.html#method.from_utf16_in
+/// [`String`]: struct.String.html
+///
+/// # Examples
+///
+/// Basic usage:
+///
+/// ```
+/// use bumpalo::{Bump, collections::String};
+///
+/// let b = Bump::new();
+///
+/// // 𝄞mu<invalid>ic
+/// let v = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
+///
+/// assert!(String::from_utf16_in(v, &b).is_err());
+/// ```
+#[derive(Debug)]
+pub struct FromUtf16Error(());
+
+impl<'bump> String<'bump> {
+    /// Creates a new empty `String`.
+    ///
+    /// Given that the `String` is empty, this will not allocate any initial
+    /// buffer. While that means that this initial operation is very
+    /// inexpensive, it may cause excessive allocation later when you add
+    /// data. If you have an idea of how much data the `String` will hold,
+    /// consider the [`with_capacity_in`] method to prevent excessive
+    /// re-allocation.
+    ///
+    /// [`with_capacity_in`]: #method.with_capacity_in
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let s = String::new_in(&b);
+    /// ```
+    #[inline]
+    pub fn new_in(bump: &'bump Bump) -> String<'bump> {
+        String {
+            vec: Vec::new_in(bump),
+        }
+    }
+
+    /// Creates a new empty `String` with a particular capacity.
+    ///
+    /// `String`s have an internal buffer to hold their data. The capacity is
+    /// the length of that buffer, and can be queried with the [`capacity`]
+    /// method. This method creates an empty `String`, but one with an initial
+    /// buffer that can hold `capacity` bytes. This is useful when you may be
+    /// appending a bunch of data to the `String`, reducing the number of
+    /// reallocations it needs to do.
+    ///
+    /// [`capacity`]: #method.capacity
+    ///
+    /// If the given capacity is `0`, no allocation will occur, and this method
+    /// is identical to the [`new_in`] method.
+    ///
+    /// [`new_in`]: #method.new
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::with_capacity_in(10, &b);
+    ///
+    /// // The String contains no chars, even though it has capacity for more
+    /// assert_eq!(s.len(), 0);
+    ///
+    /// // These are all done without reallocating...
+    /// let cap = s.capacity();
+    /// for _ in 0..10 {
+    ///     s.push('a');
+    /// }
+    ///
+    /// assert_eq!(s.capacity(), cap);
+    ///
+    /// // ...but this may make the vector reallocate
+    /// s.push('a');
+    /// ```
+    #[inline]
+    pub fn with_capacity_in(capacity: usize, bump: &'bump Bump) -> String<'bump> {
+        String {
+            vec: Vec::with_capacity_in(capacity, bump),
+        }
+    }
+
+    /// Converts a vector of bytes to a `String`.
+    ///
+    /// A string (`String`) is made of bytes ([`u8`]), and a vector of bytes
+    /// ([`Vec<u8>`]) is made of bytes, so this function converts between the
+    /// two. Not all byte slices are valid `String`s, however: `String`
+    /// requires that it is valid UTF-8. `from_utf8()` checks to ensure that
+    /// the bytes are valid UTF-8, and then does the conversion.
+    ///
+    /// If you are sure that the byte slice is valid UTF-8, and you don't want
+    /// to incur the overhead of the validity check, there is an unsafe version
+    /// of this function, [`from_utf8_unchecked`], which has the same behavior
+    /// but skips the check.
+    ///
+    /// This method will take care to not copy the vector, for efficiency's
+    /// sake.
+    ///
+    /// If you need a [`&str`] instead of a `String`, consider
+    /// [`str::from_utf8`].
+    ///
+    /// The inverse of this method is [`into_bytes`].
+    ///
+    /// # Errors
+    ///
+    /// Returns [`Err`] if the slice is not UTF-8 with a description as to why the
+    /// provided bytes are not UTF-8. The vector you moved in is also included.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// // some bytes, in a vector
+    /// let sparkle_heart = bumpalo::vec![in &b; 240, 159, 146, 150];
+    ///
+    /// // We know these bytes are valid, so we'll use `unwrap()`.
+    /// let sparkle_heart = String::from_utf8(sparkle_heart).unwrap();
+    ///
+    /// assert_eq!("💖", sparkle_heart);
+    /// ```
+    ///
+    /// Incorrect bytes:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// // some invalid bytes, in a vector
+    /// let sparkle_heart = bumpalo::vec![in &b; 0, 159, 146, 150];
+    ///
+    /// assert!(String::from_utf8(sparkle_heart).is_err());
+    /// ```
+    ///
+    /// See the docs for [`FromUtf8Error`] for more details on what you can do
+    /// with this error.
+    ///
+    /// [`from_utf8_unchecked`]: struct.String.html#method.from_utf8_unchecked
+    /// [`&str`]: https://doc.rust-lang.org/std/primitive.str.html
+    /// [`u8`]: https://doc.rust-lang.org/std/primitive.u8.html
+    /// [`Vec<u8>`]: ../vec/struct.Vec.html
+    /// [`str::from_utf8`]: https://doc.rust-lang.org/std/str/fn.from_utf8.html
+    /// [`into_bytes`]: struct.String.html#method.into_bytes
+    /// [`FromUtf8Error`]: struct.FromUtf8Error.html
+    /// [`Err`]: https://doc.rust-lang.org/std/result/enum.Result.html#variant.Err
+    #[inline]
+    pub fn from_utf8(vec: Vec<'bump, u8>) -> Result<String<'bump>, FromUtf8Error<'bump>> {
+        match str::from_utf8(&vec) {
+            Ok(..) => Ok(String { vec }),
+            Err(e) => Err(FromUtf8Error {
+                bytes: vec,
+                error: e,
+            }),
+        }
+    }
+
+    /// Converts a slice of bytes to a string, including invalid characters.
+    ///
+    /// Strings are made of bytes ([`u8`]), and a slice of bytes
+    /// ([`&[u8]`][slice]) is made of bytes, so this function converts
+    /// between the two. Not all byte slices are valid strings, however: strings
+    /// are required to be valid UTF-8. During this conversion,
+    /// `from_utf8_lossy_in()` will replace any invalid UTF-8 sequences with
+    /// [`U+FFFD REPLACEMENT CHARACTER`][U+FFFD], which looks like this: �
+    ///
+    /// [`u8`]: https://doc.rust-lang.org/std/primitive.u8.html
+    /// [slice]: https://doc.rust-lang.org/std/primitive.slice.html
+    /// [U+FFFD]: https://doc.rust-lang.org/std/char/constant.REPLACEMENT_CHARACTER.html
+    ///
+    /// If you are sure that the byte slice is valid UTF-8, and you don't want
+    /// to incur the overhead of the conversion, there is an unsafe version
+    /// of this function, [`from_utf8_unchecked`], which has the same behavior
+    /// but skips the checks.
+    ///
+    /// [`from_utf8_unchecked`]: struct.String.html#method.from_utf8_unchecked
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{collections::String, Bump, vec};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// // some bytes, in a vector
+    /// let sparkle_heart = bumpalo::vec![in &b; 240, 159, 146, 150];
+    ///
+    /// let sparkle_heart = String::from_utf8_lossy_in(&sparkle_heart, &b);
+    ///
+    /// assert_eq!("💖", sparkle_heart);
+    /// ```
+    ///
+    /// Incorrect bytes:
+    ///
+    /// ```
+    /// use bumpalo::{collections::String, Bump, vec};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// // some invalid bytes
+    /// let input = b"Hello \xF0\x90\x80World";
+    /// let output = String::from_utf8_lossy_in(input, &b);
+    ///
+    /// assert_eq!("Hello �World", output);
+    /// ```
+    pub fn from_utf8_lossy_in(v: &[u8], bump: &'bump Bump) -> String<'bump> {
+        let mut iter = lossy::Utf8Lossy::from_bytes(v).chunks();
+
+        let (first_valid, first_broken) = if let Some(chunk) = iter.next() {
+            let lossy::Utf8LossyChunk { valid, broken } = chunk;
+            if valid.len() == v.len() {
+                debug_assert!(broken.is_empty());
+                unsafe {
+                    return String::from_utf8_unchecked(Vec::from_iter_in(v.iter().cloned(), bump));
+                }
+            }
+            (valid, broken)
+        } else {
+            return String::from_str_in("", bump);
+        };
+
+        const REPLACEMENT: &str = "\u{FFFD}";
+
+        let mut res = String::with_capacity_in(v.len(), bump);
+        res.push_str(first_valid);
+        if !first_broken.is_empty() {
+            res.push_str(REPLACEMENT);
+        }
+
+        for lossy::Utf8LossyChunk { valid, broken } in iter {
+            res.push_str(valid);
+            if !broken.is_empty() {
+                res.push_str(REPLACEMENT);
+            }
+        }
+
+        res
+    }
+
+    /// Decode a UTF-16 encoded slice `v` into a `String`, returning [`Err`]
+    /// if `v` contains any invalid data.
+    ///
+    /// [`Err`]: https://doc.rust-lang.org/std/result/enum.Result.html#variant.Err
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// // 𝄞music
+    /// let v = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0x0073, 0x0069, 0x0063];
+    /// assert_eq!(String::from_str_in("𝄞music", &b), String::from_utf16_in(v, &b).unwrap());
+    ///
+    /// // 𝄞mu<invalid>ic
+    /// let v = &[0xD834, 0xDD1E, 0x006d, 0x0075, 0xD800, 0x0069, 0x0063];
+    /// assert!(String::from_utf16_in(v, &b).is_err());
+    /// ```
+    pub fn from_utf16_in(v: &[u16], bump: &'bump Bump) -> Result<String<'bump>, FromUtf16Error> {
+        let mut ret = String::with_capacity_in(v.len(), bump);
+        for c in decode_utf16(v.iter().cloned()) {
+            if let Ok(c) = c {
+                ret.push(c);
+            } else {
+                return Err(FromUtf16Error(()));
+            }
+        }
+        Ok(ret)
+    }
+
+    /// Construct a new `String<'bump>` from a string slice.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let s = String::from_str_in("hello", &b);
+    /// assert_eq!(s, "hello");
+    /// ```
+    pub fn from_str_in(s: &str, bump: &'bump Bump) -> String<'bump> {
+        let mut t = String::with_capacity_in(s.len(), bump);
+        t.push_str(s);
+        t
+    }
+
+    /// Construct a new `String<'bump>` from an iterator of `char`s.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let s = String::from_iter_in(['h', 'e', 'l', 'l', 'o'].iter().cloned(), &b);
+    /// assert_eq!(s, "hello");
+    /// ```
+    pub fn from_iter_in<I: IntoIterator<Item = char>>(iter: I, bump: &'bump Bump) -> String<'bump> {
+        let mut s = String::new_in(bump);
+        for c in iter {
+            s.push(c);
+        }
+        s
+    }
+
+    /// Creates a new `String` from a length, capacity, and pointer.
+    ///
+    /// # Safety
+    ///
+    /// This is highly unsafe, due to the number of invariants that aren't
+    /// checked:
+    ///
+    /// * The memory at `ptr` needs to have been previously allocated by the
+    ///   same allocator the standard library uses.
+    /// * `length` needs to be less than or equal to `capacity`.
+    /// * `capacity` needs to be the correct value.
+    ///
+    /// Violating these may cause problems like corrupting the allocator's
+    /// internal data structures.
+    ///
+    /// The ownership of `ptr` is effectively transferred to the
+    /// `String` which may then deallocate, reallocate or change the
+    /// contents of memory pointed to by the pointer at will. Ensure
+    /// that nothing else uses the pointer after calling this
+    /// function.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    /// use std::mem;
+    ///
+    /// let b = Bump::new();
+    ///
+    /// unsafe {
+    ///     let mut s = String::from_str_in("hello", &b);
+    ///     let ptr = s.as_mut_ptr();
+    ///     let len = s.len();
+    ///     let capacity = s.capacity();
+    ///
+    ///     mem::forget(s);
+    ///
+    ///     let s = String::from_raw_parts_in(ptr, len, capacity, &b);
+    ///
+    ///     assert_eq!(s, "hello");
+    /// }
+    /// ```
+    #[inline]
+    pub unsafe fn from_raw_parts_in(
+        buf: *mut u8,
+        length: usize,
+        capacity: usize,
+        bump: &'bump Bump,
+    ) -> String<'bump> {
+        String {
+            vec: Vec::from_raw_parts_in(buf, length, capacity, bump),
+        }
+    }
+
+    /// Converts a vector of bytes to a `String` without checking that the
+    /// string contains valid UTF-8.
+    ///
+    /// See the safe version, [`from_utf8`], for more details.
+    ///
+    /// [`from_utf8`]: struct.String.html#method.from_utf8
+    ///
+    /// # Safety
+    ///
+    /// This function is unsafe because it does not check that the bytes passed
+    /// to it are valid UTF-8. If this constraint is violated, it may cause
+    /// memory unsafety issues with future users of the `String`,
+    /// as it is assumed that `String`s are valid UTF-8.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// // some bytes, in a vector
+    /// let sparkle_heart = bumpalo::vec![in &b; 240, 159, 146, 150];
+    ///
+    /// let sparkle_heart = unsafe {
+    ///     String::from_utf8_unchecked(sparkle_heart)
+    /// };
+    ///
+    /// assert_eq!("💖", sparkle_heart);
+    /// ```
+    #[inline]
+    pub unsafe fn from_utf8_unchecked(bytes: Vec<'bump, u8>) -> String<'bump> {
+        String { vec: bytes }
+    }
+
+    /// Returns a shared reference to the allocator backing this `String`.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// // uses the same allocator as the provided `String`
+    /// fn copy_string<'bump>(s: &String<'bump>) -> &'bump str {
+    ///     s.bump().alloc_str(s.as_str())
+    /// }
+    /// ```
+    #[inline]
+    #[must_use]
+    pub fn bump(&self) -> &'bump Bump {
+        self.vec.bump()
+    }
+
+    /// Converts a `String` into a byte vector.
+    ///
+    /// This consumes the `String`, so we do not need to copy its contents.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let s = String::from_str_in("hello", &b);
+    ///
+    /// assert_eq!(s.into_bytes(), [104, 101, 108, 108, 111]);
+    /// ```
+    #[inline]
+    pub fn into_bytes(self) -> Vec<'bump, u8> {
+        self.vec
+    }
+
+    /// Convert this `String<'bump>` into a `&'bump str`. This is analogous to
+    /// [`std::string::String::into_boxed_str`][into_boxed_str].
+    ///
+    /// [into_boxed_str]: https://doc.rust-lang.org/std/string/struct.String.html#method.into_boxed_str
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let s = String::from_str_in("foo", &b);
+    ///
+    /// assert_eq!(s.into_bump_str(), "foo");
+    /// ```
+    pub fn into_bump_str(self) -> &'bump str {
+        let s = unsafe {
+            let s = self.as_str();
+            mem::transmute(s)
+        };
+        mem::forget(self);
+        s
+    }
+
+    /// Extracts a string slice containing the entire `String`.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let s = String::from_str_in("foo", &b);
+    ///
+    /// assert_eq!("foo", s.as_str());
+    /// ```
+    #[inline]
+    pub fn as_str(&self) -> &str {
+        self
+    }
+
+    /// Converts a `String` into a mutable string slice.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::from_str_in("foobar", &b);
+    /// let s_mut_str = s.as_mut_str();
+    ///
+    /// s_mut_str.make_ascii_uppercase();
+    ///
+    /// assert_eq!("FOOBAR", s_mut_str);
+    /// ```
+    #[inline]
+    pub fn as_mut_str(&mut self) -> &mut str {
+        self
+    }
+
+    /// Appends a given string slice onto the end of this `String`.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::from_str_in("foo", &b);
+    ///
+    /// s.push_str("bar");
+    ///
+    /// assert_eq!("foobar", s);
+    /// ```
+    #[inline]
+    pub fn push_str(&mut self, string: &str) {
+        self.vec.extend_from_slice(string.as_bytes())
+    }
+
+    /// Returns this `String`'s capacity, in bytes.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let s = String::with_capacity_in(10, &b);
+    ///
+    /// assert!(s.capacity() >= 10);
+    /// ```
+    #[inline]
+    pub fn capacity(&self) -> usize {
+        self.vec.capacity()
+    }
+
+    /// Ensures that this `String`'s capacity is at least `additional` bytes
+    /// larger than its length.
+    ///
+    /// The capacity may be increased by more than `additional` bytes if it
+    /// chooses, to prevent frequent reallocations.
+    ///
+    /// If you do not want this "at least" behavior, see the [`reserve_exact`]
+    /// method.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the new capacity overflows [`usize`].
+    ///
+    /// [`reserve_exact`]: struct.String.html#method.reserve_exact
+    /// [`usize`]: https://doc.rust-lang.org/std/primitive.usize.html
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::new_in(&b);
+    ///
+    /// s.reserve(10);
+    ///
+    /// assert!(s.capacity() >= 10);
+    /// ```
+    ///
+    /// This may not actually increase the capacity:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::with_capacity_in(10, &b);
+    /// s.push('a');
+    /// s.push('b');
+    ///
+    /// // s now has a length of 2 and a capacity of 10
+    /// assert_eq!(2, s.len());
+    /// assert_eq!(10, s.capacity());
+    ///
+    /// // Since we already have an extra 8 capacity, calling this...
+    /// s.reserve(8);
+    ///
+    /// // ... doesn't actually increase.
+    /// assert_eq!(10, s.capacity());
+    /// ```
+    #[inline]
+    pub fn reserve(&mut self, additional: usize) {
+        self.vec.reserve(additional)
+    }
+
+    /// Ensures that this `String`'s capacity is `additional` bytes
+    /// larger than its length.
+    ///
+    /// Consider using the [`reserve`] method unless you absolutely know
+    /// better than the allocator.
+    ///
+    /// [`reserve`]: #method.reserve
+    ///
+    /// # Panics
+    ///
+    /// Panics if the new capacity overflows `usize`.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::new_in(&b);
+    ///
+    /// s.reserve_exact(10);
+    ///
+    /// assert!(s.capacity() >= 10);
+    /// ```
+    ///
+    /// This may not actually increase the capacity:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::with_capacity_in(10, &b);
+    /// s.push('a');
+    /// s.push('b');
+    ///
+    /// // s now has a length of 2 and a capacity of 10
+    /// assert_eq!(2, s.len());
+    /// assert_eq!(10, s.capacity());
+    ///
+    /// // Since we already have an extra 8 capacity, calling this...
+    /// s.reserve_exact(8);
+    ///
+    /// // ... doesn't actually increase.
+    /// assert_eq!(10, s.capacity());
+    /// ```
+    #[inline]
+    pub fn reserve_exact(&mut self, additional: usize) {
+        self.vec.reserve_exact(additional)
+    }
+
+    /// Shrinks the capacity of this `String` to match its length.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::from_str_in("foo", &b);
+    ///
+    /// s.reserve(100);
+    /// assert!(s.capacity() >= 100);
+    ///
+    /// s.shrink_to_fit();
+    /// assert_eq!(3, s.capacity());
+    /// ```
+    #[inline]
+    pub fn shrink_to_fit(&mut self) {
+        self.vec.shrink_to_fit()
+    }
+
+    /// Appends the given [`char`] to the end of this `String`.
+    ///
+    /// [`char`]: https://doc.rust-lang.org/std/primitive.char.html
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::from_str_in("abc", &b);
+    ///
+    /// s.push('1');
+    /// s.push('2');
+    /// s.push('3');
+    ///
+    /// assert_eq!("abc123", s);
+    /// ```
+    #[inline]
+    pub fn push(&mut self, ch: char) {
+        match ch.len_utf8() {
+            1 => self.vec.push(ch as u8),
+            _ => self
+                .vec
+                .extend_from_slice(ch.encode_utf8(&mut [0; 4]).as_bytes()),
+        }
+    }
+
+    /// Returns a byte slice of this `String`'s contents.
+    ///
+    /// The inverse of this method is [`from_utf8`].
+    ///
+    /// [`from_utf8`]: #method.from_utf8
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let s = String::from_str_in("hello", &b);
+    ///
+    /// assert_eq!(&[104, 101, 108, 108, 111], s.as_bytes());
+    /// ```
+    #[inline]
+    pub fn as_bytes(&self) -> &[u8] {
+        &self.vec
+    }
+
+    /// Shortens this `String` to the specified length.
+    ///
+    /// If `new_len` is greater than the string's current length, this has no
+    /// effect.
+    ///
+    /// Note that this method has no effect on the allocated capacity
+    /// of the string.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `new_len` does not lie on a [`char`] boundary.
+    ///
+    /// [`char`]: https://doc.rust-lang.org/std/primitive.char.html
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::from_str_in("hello", &b);
+    ///
+    /// s.truncate(2);
+    ///
+    /// assert_eq!("he", s);
+    /// ```
+    #[inline]
+    pub fn truncate(&mut self, new_len: usize) {
+        if new_len <= self.len() {
+            assert!(self.is_char_boundary(new_len));
+            self.vec.truncate(new_len)
+        }
+    }
+
+    /// Removes the last character from the string buffer and returns it.
+    ///
+    /// Returns [`None`] if this `String` is empty.
+    ///
+    /// [`None`]: https://doc.rust-lang.org/std/option/enum.Option.html#variant.None
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::from_str_in("foo", &b);
+    ///
+    /// assert_eq!(s.pop(), Some('o'));
+    /// assert_eq!(s.pop(), Some('o'));
+    /// assert_eq!(s.pop(), Some('f'));
+    ///
+    /// assert_eq!(s.pop(), None);
+    /// ```
+    #[inline]
+    pub fn pop(&mut self) -> Option<char> {
+        let ch = self.chars().rev().next()?;
+        let newlen = self.len() - ch.len_utf8();
+        unsafe {
+            self.vec.set_len(newlen);
+        }
+        Some(ch)
+    }
+
+    /// Removes a [`char`] from this `String` at a byte position and returns it.
+    ///
+    /// This is an `O(n)` operation, as it requires copying every element in the
+    /// buffer.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `idx` is larger than or equal to the `String`'s length,
+    /// or if it does not lie on a [`char`] boundary.
+    ///
+    /// [`char`]: https://doc.rust-lang.org/std/primitive.char.html
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::from_str_in("foo", &b);
+    ///
+    /// assert_eq!(s.remove(0), 'f');
+    /// assert_eq!(s.remove(1), 'o');
+    /// assert_eq!(s.remove(0), 'o');
+    /// ```
+    #[inline]
+    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.vec.as_ptr().add(next),
+                self.vec.as_mut_ptr().add(idx),
+                len - next,
+            );
+            self.vec.set_len(len - (next - idx));
+        }
+        ch
+    }
+
+    /// Retains only the characters specified by the predicate.
+    ///
+    /// In other words, remove all characters `c` such that `f(c)` returns `false`.
+    /// This method operates in place and preserves the order of the retained
+    /// characters.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::from_str_in("f_o_ob_ar", &b);
+    ///
+    /// s.retain(|c| c != '_');
+    ///
+    /// assert_eq!(s, "foobar");
+    /// ```
+    #[inline]
+    pub fn retain<F>(&mut self, mut f: F)
+    where
+        F: FnMut(char) -> bool,
+    {
+        let len = self.len();
+        let mut del_bytes = 0;
+        let mut idx = 0;
+
+        while idx < len {
+            let ch = unsafe { self.get_unchecked(idx..len).chars().next().unwrap() };
+            let ch_len = ch.len_utf8();
+
+            if !f(ch) {
+                del_bytes += ch_len;
+            } else if del_bytes > 0 {
+                unsafe {
+                    ptr::copy(
+                        self.vec.as_ptr().add(idx),
+                        self.vec.as_mut_ptr().add(idx - del_bytes),
+                        ch_len,
+                    );
+                }
+            }
+
+            // Point idx to the next char
+            idx += ch_len;
+        }
+
+        if del_bytes > 0 {
+            unsafe {
+                self.vec.set_len(len - del_bytes);
+            }
+        }
+    }
+
+    /// Inserts a character into this `String` at a byte position.
+    ///
+    /// This is an `O(n)` operation as it requires copying every element in the
+    /// buffer.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `idx` is larger than the `String`'s length, or if it does not
+    /// lie on a [`char`] boundary.
+    ///
+    /// [`char`]: https://doc.rust-lang.org/std/primitive.char.html
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::with_capacity_in(3, &b);
+    ///
+    /// s.insert(0, 'f');
+    /// s.insert(1, 'o');
+    /// s.insert(2, 'o');
+    ///
+    /// assert_eq!("foo", s);
+    /// ```
+    #[inline]
+    pub fn insert(&mut self, idx: usize, ch: char) {
+        assert!(self.is_char_boundary(idx));
+        let mut bits = [0; 4];
+        let bits = ch.encode_utf8(&mut bits).as_bytes();
+
+        unsafe {
+            self.insert_bytes(idx, bits);
+        }
+    }
+
+    unsafe fn insert_bytes(&mut self, idx: usize, bytes: &[u8]) {
+        let len = self.len();
+        let amt = bytes.len();
+        self.vec.reserve(amt);
+
+        ptr::copy(
+            self.vec.as_ptr().add(idx),
+            self.vec.as_mut_ptr().add(idx + amt),
+            len - idx,
+        );
+        ptr::copy(bytes.as_ptr(), self.vec.as_mut_ptr().add(idx), amt);
+        self.vec.set_len(len + amt);
+    }
+
+    /// Inserts a string slice into this `String` at a byte position.
+    ///
+    /// This is an `O(n)` operation as it requires copying every element in the
+    /// buffer.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `idx` is larger than the `String`'s length, or if it does not
+    /// lie on a [`char`] boundary.
+    ///
+    /// [`char`]: https://doc.rust-lang.org/std/primitive.char.html
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::from_str_in("bar", &b);
+    ///
+    /// s.insert_str(0, "foo");
+    ///
+    /// assert_eq!("foobar", s);
+    /// ```
+    #[inline]
+    pub fn insert_str(&mut self, idx: usize, string: &str) {
+        assert!(self.is_char_boundary(idx));
+
+        unsafe {
+            self.insert_bytes(idx, string.as_bytes());
+        }
+    }
+
+    /// Returns a mutable reference to the contents of this `String`.
+    ///
+    /// # Safety
+    ///
+    /// This function is unsafe because the returned `&mut Vec` allows writing
+    /// bytes which are not valid UTF-8. If this constraint is violated, using
+    /// the original `String` after dropping the `&mut Vec` may violate memory
+    /// safety, as it is assumed that `String`s are valid UTF-8.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::from_str_in("hello", &b);
+    ///
+    /// unsafe {
+    ///     let vec = s.as_mut_vec();
+    ///     assert_eq!(vec, &[104, 101, 108, 108, 111]);
+    ///
+    ///     vec.reverse();
+    /// }
+    /// assert_eq!(s, "olleh");
+    /// ```
+    #[inline]
+    pub unsafe fn as_mut_vec(&mut self) -> &mut Vec<'bump, u8> {
+        &mut self.vec
+    }
+
+    /// Returns the length of this `String`, in bytes.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let a = String::from_str_in("foo", &b);
+    ///
+    /// assert_eq!(a.len(), 3);
+    /// ```
+    #[inline]
+    pub fn len(&self) -> usize {
+        self.vec.len()
+    }
+
+    /// Returns `true` if this `String` has a length of zero.
+    ///
+    /// Returns `false` otherwise.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut v = String::new_in(&b);
+    /// assert!(v.is_empty());
+    ///
+    /// v.push('a');
+    /// assert!(!v.is_empty());
+    /// ```
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
+    /// Splits the string into two at the given index.
+    ///
+    /// Returns a newly allocated `String`. `self` contains bytes `[0, at)`, and
+    /// the returned `String` contains bytes `[at, len)`. `at` must be on the
+    /// boundary of a UTF-8 code point.
+    ///
+    /// Note that the capacity of `self` does not change.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `at` is not on a UTF-8 code point boundary, or if it is beyond the last
+    /// code point of the string.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut hello = String::from_str_in("Hello, World!", &b);
+    /// let world = hello.split_off(7);
+    /// assert_eq!(hello, "Hello, ");
+    /// assert_eq!(world, "World!");
+    /// ```
+    #[inline]
+    pub fn split_off(&mut self, at: usize) -> String<'bump> {
+        assert!(self.is_char_boundary(at));
+        let other = self.vec.split_off(at);
+        unsafe { String::from_utf8_unchecked(other) }
+    }
+
+    /// Truncates this `String`, removing all contents.
+    ///
+    /// While this means the `String` will have a length of zero, it does not
+    /// touch its capacity.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::from_str_in("foo", &b);
+    ///
+    /// s.clear();
+    ///
+    /// assert!(s.is_empty());
+    /// assert_eq!(0, s.len());
+    /// assert_eq!(3, s.capacity());
+    /// ```
+    #[inline]
+    pub fn clear(&mut self) {
+        self.vec.clear()
+    }
+
+    /// Creates a draining iterator that removes the specified range in the `String`
+    /// and yields the removed `chars`.
+    ///
+    /// Note: The element range is removed even if the iterator is not
+    /// consumed until the end.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the starting point or end point do not lie on a [`char`]
+    /// boundary, or if they're out of bounds.
+    ///
+    /// [`char`]: https://doc.rust-lang.org/std/primitive.char.html
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::from_str_in("α is alpha, β is beta", &b);
+    /// let beta_offset = s.find('β').unwrap_or(s.len());
+    ///
+    /// // Remove the range up until the β from the string
+    /// let t = String::from_iter_in(s.drain(..beta_offset), &b);
+    /// assert_eq!(t, "α is alpha, ");
+    /// assert_eq!(s, "β is beta");
+    ///
+    /// // A full range clears the string
+    /// drop(s.drain(..));
+    /// assert_eq!(s, "");
+    /// ```
+    pub fn drain<'a, R>(&'a mut self, range: R) -> Drain<'a, 'bump>
+    where
+        R: RangeBounds<usize>,
+    {
+        // Memory safety
+        //
+        // The String version of Drain does not have the memory safety issues
+        // of the vector version. The data is just plain bytes.
+        // Because the range removal happens in Drop, if the Drain iterator is leaked,
+        // the removal will not happen.
+        let len = self.len();
+        let start = match range.start_bound() {
+            Included(&n) => n,
+            Excluded(&n) => n + 1,
+            Unbounded => 0,
+        };
+        let end = match range.end_bound() {
+            Included(&n) => n + 1,
+            Excluded(&n) => n,
+            Unbounded => len,
+        };
+
+        // Take out two simultaneous borrows. The &mut String won't be accessed
+        // until iteration is over, in Drop.
+        let self_ptr = self as *mut _;
+        // slicing does the appropriate bounds checks
+        let chars_iter = self[start..end].chars();
+
+        Drain {
+            start,
+            end,
+            iter: chars_iter,
+            string: self_ptr,
+        }
+    }
+
+    /// Removes the specified range in the string,
+    /// and replaces it with the given string.
+    /// The given string doesn't need to be the same length as the range.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the starting point or end point do not lie on a [`char`]
+    /// boundary, or if they're out of bounds.
+    ///
+    /// [`char`]: https://doc.rust-lang.org/std/primitive.char.html
+    /// [`Vec::splice`]: ../vec/struct.Vec.html#method.splice
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// let mut s = String::from_str_in("α is alpha, β is beta", &b);
+    /// let beta_offset = s.find('β').unwrap_or(s.len());
+    ///
+    /// // Replace the range up until the β from the string
+    /// s.replace_range(..beta_offset, "Α is capital alpha; ");
+    /// assert_eq!(s, "Α is capital alpha; β is beta");
+    /// ```
+    pub fn replace_range<R>(&mut self, range: R, replace_with: &str)
+    where
+        R: RangeBounds<usize>,
+    {
+        // Memory safety
+        //
+        // Replace_range does not have the memory safety issues of a vector Splice.
+        // of the vector version. The data is just plain bytes.
+
+        match range.start_bound() {
+            Included(&n) => assert!(self.is_char_boundary(n)),
+            Excluded(&n) => assert!(self.is_char_boundary(n + 1)),
+            Unbounded => {}
+        };
+        match range.end_bound() {
+            Included(&n) => assert!(self.is_char_boundary(n + 1)),
+            Excluded(&n) => assert!(self.is_char_boundary(n)),
+            Unbounded => {}
+        };
+
+        unsafe { self.as_mut_vec() }.splice(range, replace_with.bytes());
+    }
+}
+
+impl<'bump> FromUtf8Error<'bump> {
+    /// Returns a slice of bytes that were attempted to convert to a `String`.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// // some invalid bytes, in a vector
+    /// let bytes = bumpalo::vec![in &b; 0, 159];
+    ///
+    /// let value = String::from_utf8(bytes);
+    ///
+    /// assert_eq!(&[0, 159], value.unwrap_err().as_bytes());
+    /// ```
+    pub fn as_bytes(&self) -> &[u8] {
+        &self.bytes[..]
+    }
+
+    /// Returns the bytes that were attempted to convert to a `String`.
+    ///
+    /// This method is carefully constructed to avoid allocation. It will
+    /// consume the error, moving out the bytes, so that a copy of the bytes
+    /// does not need to be made.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// // some invalid bytes, in a vector
+    /// let bytes = bumpalo::vec![in &b; 0, 159];
+    ///
+    /// let value = String::from_utf8(bytes);
+    ///
+    /// assert_eq!(bumpalo::vec![in &b; 0, 159], value.unwrap_err().into_bytes());
+    /// ```
+    pub fn into_bytes(self) -> Vec<'bump, u8> {
+        self.bytes
+    }
+
+    /// Fetch a `Utf8Error` to get more details about the conversion failure.
+    ///
+    /// The [`Utf8Error`] type provided by [`std::str`] represents an error that may
+    /// occur when converting a slice of [`u8`]s to a [`&str`]. In this sense, it's
+    /// an analogue to `FromUtf8Error`. See its documentation for more details
+    /// on using it.
+    ///
+    /// [`Utf8Error`]: https://doc.rust-lang.org/std/str/struct.Utf8Error.html
+    /// [`std::str`]: https://doc.rust-lang.org/std/str/index.html
+    /// [`u8`]: https://doc.rust-lang.org/std/primitive.u8.html
+    /// [`&str`]: https://doc.rust-lang.org/std/primitive.str.html
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// use bumpalo::{Bump, collections::String};
+    ///
+    /// let b = Bump::new();
+    ///
+    /// // some invalid bytes, in a vector
+    /// let bytes = bumpalo::vec![in &b; 0, 159];
+    ///
+    /// let error = String::from_utf8(bytes).unwrap_err().utf8_error();
+    ///
+    /// // the first byte is invalid here
+    /// assert_eq!(1, error.valid_up_to());
+    /// ```
+    pub fn utf8_error(&self) -> Utf8Error {
+        self.error
+    }
+}
+
+impl<'bump> fmt::Display for FromUtf8Error<'bump> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Display::fmt(&self.error, f)
+    }
+}
+
+impl fmt::Display for FromUtf16Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Display::fmt("invalid utf-16: lone surrogate found", f)
+    }
+}
+
+impl<'bump> Clone for String<'bump> {
+    fn clone(&self) -> Self {
+        String {
+            vec: self.vec.clone(),
+        }
+    }
+
+    fn clone_from(&mut self, source: &Self) {
+        self.vec.clone_from(&source.vec);
+    }
+}
+
+impl<'bump> Extend<char> for String<'bump> {
+    fn extend<I: IntoIterator<Item = char>>(&mut self, iter: I) {
+        let iterator = iter.into_iter();
+        let (lower_bound, _) = iterator.size_hint();
+        self.reserve(lower_bound);
+        for ch in iterator {
+            self.push(ch)
+        }
+    }
+}
+
+impl<'a, 'bump> Extend<&'a char> for String<'bump> {
+    fn extend<I: IntoIterator<Item = &'a char>>(&mut self, iter: I) {
+        self.extend(iter.into_iter().cloned());
+    }
+}
+
+impl<'a, 'bump> Extend<&'a str> for String<'bump> {
+    fn extend<I: IntoIterator<Item = &'a str>>(&mut self, iter: I) {
+        for s in iter {
+            self.push_str(s)
+        }
+    }
+}
+
+impl<'bump> Extend<String<'bump>> for String<'bump> {
+    fn extend<I: IntoIterator<Item = String<'bump>>>(&mut self, iter: I) {
+        for s in iter {
+            self.push_str(&s)
+        }
+    }
+}
+
+impl<'bump> Extend<core_alloc::string::String> for String<'bump> {
+    fn extend<I: IntoIterator<Item = core_alloc::string::String>>(&mut self, iter: I) {
+        for s in iter {
+            self.push_str(&s)
+        }
+    }
+}
+
+impl<'a, 'bump> Extend<Cow<'a, str>> for String<'bump> {
+    fn extend<I: IntoIterator<Item = Cow<'a, str>>>(&mut self, iter: I) {
+        for s in iter {
+            self.push_str(&s)
+        }
+    }
+}
+
+impl<'bump> PartialEq for String<'bump> {
+    #[inline]
+    fn eq(&self, other: &String) -> bool {
+        PartialEq::eq(&self[..], &other[..])
+    }
+}
+
+macro_rules! impl_eq {
+    ($lhs:ty, $rhs: ty) => {
+        impl<'a, 'bump> PartialEq<$rhs> for $lhs {
+            #[inline]
+            fn eq(&self, other: &$rhs) -> bool {
+                PartialEq::eq(&self[..], &other[..])
+            }
+        }
+
+        impl<'a, 'b, 'bump> PartialEq<$lhs> for $rhs {
+            #[inline]
+            fn eq(&self, other: &$lhs) -> bool {
+                PartialEq::eq(&self[..], &other[..])
+            }
+        }
+    };
+}
+
+impl_eq! { String<'bump>, str }
+impl_eq! { String<'bump>, &'a str }
+impl_eq! { Cow<'a, str>, String<'bump> }
+impl_eq! { core_alloc::string::String, String<'bump> }
+
+impl<'bump> fmt::Display for String<'bump> {
+    #[inline]
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Display::fmt(&**self, f)
+    }
+}
+
+impl<'bump> fmt::Debug for String<'bump> {
+    #[inline]
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Debug::fmt(&**self, f)
+    }
+}
+
+impl<'bump> hash::Hash for String<'bump> {
+    #[inline]
+    fn hash<H: hash::Hasher>(&self, hasher: &mut H) {
+        (**self).hash(hasher)
+    }
+}
+
+/// Implements the `+` operator for concatenating two strings.
+///
+/// This consumes the `String<'bump>` on the left-hand side and re-uses its buffer (growing it if
+/// necessary). This is done to avoid allocating a new `String<'bump>` and copying the entire contents on
+/// every operation, which would lead to `O(n^2)` running time when building an `n`-byte string by
+/// repeated concatenation.
+///
+/// The string on the right-hand side is only borrowed; its contents are copied into the returned
+/// `String<'bump>`.
+///
+/// # Examples
+///
+/// Concatenating two `String<'bump>`s takes the first by value and borrows the second:
+///
+/// ```
+/// use bumpalo::{Bump, collections::String};
+///
+/// let bump = Bump::new();
+///
+/// let a = String::from_str_in("hello", &bump);
+/// let b = String::from_str_in(" world", &bump);
+/// let c = a + &b;
+/// // `a` is moved and can no longer be used here.
+/// ```
+///
+/// If you want to keep using the first `String`, you can clone it and append to the clone instead:
+///
+/// ```
+/// use bumpalo::{Bump, collections::String};
+///
+/// let bump = Bump::new();
+///
+/// let a = String::from_str_in("hello", &bump);
+/// let b = String::from_str_in(" world", &bump);
+/// let c = a.clone() + &b;
+/// // `a` is still valid here.
+/// ```
+///
+/// Concatenating `&str` slices can be done by converting the first to a `String`:
+///
+/// ```
+/// use bumpalo::{Bump, collections::String};
+///
+/// let bump = Bump::new();
+///
+/// let a = "hello";
+/// let b = " world";
+/// let c = String::from_str_in(a, &bump) + b;
+/// ```
+impl<'a, 'bump> Add<&'a str> for String<'bump> {
+    type Output = String<'bump>;
+
+    #[inline]
+    fn add(mut self, other: &str) -> String<'bump> {
+        self.push_str(other);
+        self
+    }
+}
+
+/// Implements the `+=` operator for appending to a `String<'bump>`.
+///
+/// This has the same behavior as the [`push_str`][String::push_str] method.
+impl<'a, 'bump> AddAssign<&'a str> for String<'bump> {
+    #[inline]
+    fn add_assign(&mut self, other: &str) {
+        self.push_str(other);
+    }
+}
+
+impl<'bump> ops::Index<ops::Range<usize>> for String<'bump> {
+    type Output = str;
+
+    #[inline]
+    fn index(&self, index: ops::Range<usize>) -> &str {
+        &self[..][index]
+    }
+}
+impl<'bump> ops::Index<ops::RangeTo<usize>> for String<'bump> {
+    type Output = str;
+
+    #[inline]
+    fn index(&self, index: ops::RangeTo<usize>) -> &str {
+        &self[..][index]
+    }
+}
+impl<'bump> ops::Index<ops::RangeFrom<usize>> for String<'bump> {
+    type Output = str;
+
+    #[inline]
+    fn index(&self, index: ops::RangeFrom<usize>) -> &str {
+        &self[..][index]
+    }
+}
+impl<'bump> ops::Index<ops::RangeFull> for String<'bump> {
+    type Output = str;
+
+    #[inline]
+    fn index(&self, _index: ops::RangeFull) -> &str {
+        unsafe { str::from_utf8_unchecked(&self.vec) }
+    }
+}
+impl<'bump> ops::Index<ops::RangeInclusive<usize>> for String<'bump> {
+    type Output = str;
+
+    #[inline]
+    fn index(&self, index: ops::RangeInclusive<usize>) -> &str {
+        Index::index(&**self, index)
+    }
+}
+impl<'bump> ops::Index<ops::RangeToInclusive<usize>> for String<'bump> {
+    type Output = str;
+
+    #[inline]
+    fn index(&self, index: ops::RangeToInclusive<usize>) -> &str {
+        Index::index(&**self, index)
+    }
+}
+
+impl<'bump> ops::IndexMut<ops::Range<usize>> for String<'bump> {
+    #[inline]
+    fn index_mut(&mut self, index: ops::Range<usize>) -> &mut str {
+        &mut self[..][index]
+    }
+}
+impl<'bump> ops::IndexMut<ops::RangeTo<usize>> for String<'bump> {
+    #[inline]
+    fn index_mut(&mut self, index: ops::RangeTo<usize>) -> &mut str {
+        &mut self[..][index]
+    }
+}
+impl<'bump> ops::IndexMut<ops::RangeFrom<usize>> for String<'bump> {
+    #[inline]
+    fn index_mut(&mut self, index: ops::RangeFrom<usize>) -> &mut str {
+        &mut self[..][index]
+    }
+}
+impl<'bump> ops::IndexMut<ops::RangeFull> for String<'bump> {
+    #[inline]
+    fn index_mut(&mut self, _index: ops::RangeFull) -> &mut str {
+        unsafe { str::from_utf8_unchecked_mut(&mut *self.vec) }
+    }
+}
+impl<'bump> ops::IndexMut<ops::RangeInclusive<usize>> for String<'bump> {
+    #[inline]
+    fn index_mut(&mut self, index: ops::RangeInclusive<usize>) -> &mut str {
+        IndexMut::index_mut(&mut **self, index)
+    }
+}
+impl<'bump> ops::IndexMut<ops::RangeToInclusive<usize>> for String<'bump> {
+    #[inline]
+    fn index_mut(&mut self, index: ops::RangeToInclusive<usize>) -> &mut str {
+        IndexMut::index_mut(&mut **self, index)
+    }
+}
+
+impl<'bump> ops::Deref for String<'bump> {
+    type Target = str;
+
+    #[inline]
+    fn deref(&self) -> &str {
+        unsafe { str::from_utf8_unchecked(&self.vec) }
+    }
+}
+
+impl<'bump> ops::DerefMut for String<'bump> {
+    #[inline]
+    fn deref_mut(&mut self) -> &mut str {
+        unsafe { str::from_utf8_unchecked_mut(&mut *self.vec) }
+    }
+}
+
+impl<'bump> AsRef<str> for String<'bump> {
+    #[inline]
+    fn as_ref(&self) -> &str {
+        self
+    }
+}
+
+impl<'bump> AsRef<[u8]> for String<'bump> {
+    #[inline]
+    fn as_ref(&self) -> &[u8] {
+        self.as_bytes()
+    }
+}
+
+impl<'bump> fmt::Write for String<'bump> {
+    #[inline]
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        self.push_str(s);
+        Ok(())
+    }
+
+    #[inline]
+    fn write_char(&mut self, c: char) -> fmt::Result {
+        self.push(c);
+        Ok(())
+    }
+}
+
+impl<'bump> Borrow<str> for String<'bump> {
+    #[inline]
+    fn borrow(&self) -> &str {
+        &self[..]
+    }
+}
+
+impl<'bump> BorrowMut<str> for String<'bump> {
+    #[inline]
+    fn borrow_mut(&mut self) -> &mut str {
+        &mut self[..]
+    }
+}
+
+/// A draining iterator for `String`.
+///
+/// This struct is created by the [`String::drain`] method. See its
+/// documentation for more information.
+pub struct Drain<'a, 'bump> {
+    /// Will be used as &'a mut String in the destructor
+    string: *mut String<'bump>,
+    /// Start of part to remove
+    start: usize,
+    /// End of part to remove
+    end: usize,
+    /// Current remaining range to remove
+    iter: Chars<'a>,
+}
+
+impl<'a, 'bump> fmt::Debug for Drain<'a, 'bump> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.pad("Drain { .. }")
+    }
+}
+
+unsafe impl<'a, 'bump> Sync for Drain<'a, 'bump> {}
+unsafe impl<'a, 'bump> Send for Drain<'a, 'bump> {}
+
+impl<'a, 'bump> Drop for Drain<'a, 'bump> {
+    fn drop(&mut self) {
+        unsafe {
+            // Use Vec::drain. "Reaffirm" the bounds checks to avoid
+            // panic code being inserted again.
+            let self_vec = (*self.string).as_mut_vec();
+            if self.start <= self.end && self.end <= self_vec.len() {
+                self_vec.drain(self.start..self.end);
+            }
+        }
+    }
+}
+
+// TODO: implement `AsRef<str/[u8]>` and `as_str`
+
+impl<'a, 'bump> Iterator for Drain<'a, 'bump> {
+    type Item = char;
+
+    #[inline]
+    fn next(&mut self) -> Option<char> {
+        self.iter.next()
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.iter.size_hint()
+    }
+}
+
+impl<'a, 'bump> DoubleEndedIterator for Drain<'a, 'bump> {
+    #[inline]
+    fn next_back(&mut self) -> Option<char> {
+        self.iter.next_back()
+    }
+}
+
+impl<'a, 'bump> FusedIterator for Drain<'a, 'bump> {}