2440 lines
71 KiB
Rust
2440 lines
71 KiB
Rust
//! A UTF-8 encoded, growable string.
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//!
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//! This module contains the [`String`] type, a trait for converting
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//! [`ToString`]s, and several error types that may result from working with
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//! [`String`]s.
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//!
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//! [`ToString`]: trait.ToString.html
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//!
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//! # Examples
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//!
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//! There are multiple ways to create a new [`String`] from a string literal:
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//!
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//! ```
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//! let s = "Hello".to_string();
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//!
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//! let s = String::from("world");
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//! let s: String = "also this".into();
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//! ```
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//!
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//! You can create a new [`String`] from an existing one by concatenating with
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//! `+`:
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//!
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//! [`String`]: struct.String.html
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//!
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//! ```
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//! let s = "Hello".to_string();
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//!
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//! let message = s + " world!";
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//! ```
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//!
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//! If you have a vector of valid UTF-8 bytes, you can make a [`String`] out of
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//! it. You can do the reverse too.
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//!
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//! ```
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//! let sparkle_heart = vec![240, 159, 146, 150];
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//!
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//! // We know these bytes are valid, so we'll use `unwrap()`.
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//! let sparkle_heart = String::from_utf8(sparkle_heart).unwrap();
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//!
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//! assert_eq!("💖", sparkle_heart);
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//!
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//! let bytes = sparkle_heart.into_bytes();
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//!
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//! assert_eq!(bytes, [240, 159, 146, 150]);
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//! ```
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#![stable(feature = "rust1", since = "1.0.0")]
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use core::char::{decode_utf16, REPLACEMENT_CHARACTER};
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use core::fmt;
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use core::hash;
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use core::iter::{FromIterator, FusedIterator};
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use core::ops::Bound::{Excluded, Included, Unbounded};
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use core::ops::{self, Add, AddAssign, Index, IndexMut, RangeBounds};
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use core::ptr;
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use core::str::{lossy, pattern::Pattern};
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use crate::borrow::{Cow, ToOwned};
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use crate::boxed::Box;
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use crate::collections::TryReserveError;
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use crate::str::{self, from_boxed_utf8_unchecked, Chars, FromStr, Utf8Error};
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use crate::vec::Vec;
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/// A UTF-8 encoded, growable string.
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///
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/// The `String` type is the most common string type that has ownership over the
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/// contents of the string. It has a close relationship with its borrowed
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/// counterpart, the primitive [`str`].
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///
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/// [`str`]: ../../std/primitive.str.html
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///
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/// # Examples
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///
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/// You can create a `String` from a literal string with [`String::from`]:
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///
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/// ```
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/// let hello = String::from("Hello, world!");
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/// ```
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///
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/// You can append a [`char`] to a `String` with the [`push`] method, and
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/// append a [`&str`] with the [`push_str`] method:
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///
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/// ```
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/// let mut hello = String::from("Hello, ");
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///
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/// hello.push('w');
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/// hello.push_str("orld!");
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/// ```
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///
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/// [`String::from`]: #method.from
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/// [`char`]: ../../std/primitive.char.html
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/// [`push`]: #method.push
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/// [`push_str`]: #method.push_str
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///
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/// If you have a vector of UTF-8 bytes, you can create a `String` from it with
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/// the [`from_utf8`] method:
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///
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/// ```
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/// // some bytes, in a vector
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/// let sparkle_heart = vec![240, 159, 146, 150];
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///
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/// // We know these bytes are valid, so we'll use `unwrap()`.
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/// let sparkle_heart = String::from_utf8(sparkle_heart).unwrap();
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///
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/// assert_eq!("💖", sparkle_heart);
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/// ```
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///
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/// [`from_utf8`]: #method.from_utf8
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///
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/// # UTF-8
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///
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/// `String`s are always valid UTF-8. This has a few implications, the first of
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/// which is that if you need a non-UTF-8 string, consider [`OsString`]. It is
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/// similar, but without the UTF-8 constraint. The second implication is that
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/// you cannot index into a `String`:
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///
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/// ```compile_fail,E0277
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/// let s = "hello";
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///
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/// println!("The first letter of s is {}", s[0]); // ERROR!!!
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/// ```
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///
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/// [`OsString`]: ../../std/ffi/struct.OsString.html
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///
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/// Indexing is intended to be a constant-time operation, but UTF-8 encoding
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/// does not allow us to do this. Furthermore, it's not clear what sort of
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/// thing the index should return: a byte, a codepoint, or a grapheme cluster.
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/// The [`bytes`] and [`chars`] methods return iterators over the first
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/// two, respectively.
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///
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/// [`bytes`]: #method.bytes
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/// [`chars`]: #method.chars
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///
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/// # Deref
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///
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/// `String`s implement [`Deref`]`<Target=str>`, and so inherit all of [`str`]'s
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/// methods. In addition, this means that you can pass a `String` to a
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/// function which takes a [`&str`] by using an ampersand (`&`):
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///
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/// ```
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/// fn takes_str(s: &str) { }
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///
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/// let s = String::from("Hello");
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///
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/// takes_str(&s);
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/// ```
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///
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/// This will create a [`&str`] from the `String` and pass it in. This
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/// conversion is very inexpensive, and so generally, functions will accept
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/// [`&str`]s as arguments unless they need a `String` for some specific
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/// reason.
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///
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/// In certain cases Rust doesn't have enough information to make this
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/// conversion, known as [`Deref`] coercion. In the following example a string
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/// slice [`&'a str`][`&str`] implements the trait `TraitExample`, and the function
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/// `example_func` takes anything that implements the trait. In this case Rust
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/// would need to make two implicit conversions, which Rust doesn't have the
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/// means to do. For that reason, the following example will not compile.
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///
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/// ```compile_fail,E0277
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/// trait TraitExample {}
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///
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/// impl<'a> TraitExample for &'a str {}
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///
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/// fn example_func<A: TraitExample>(example_arg: A) {}
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///
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/// let example_string = String::from("example_string");
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/// example_func(&example_string);
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/// ```
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///
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/// There are two options that would work instead. The first would be to
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/// change the line `example_func(&example_string);` to
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/// `example_func(example_string.as_str());`, using the method [`as_str()`]
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/// to explicitly extract the string slice containing the string. The second
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/// way changes `example_func(&example_string);` to
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/// `example_func(&*example_string);`. In this case we are dereferencing a
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/// `String` to a [`str`][`&str`], then referencing the [`str`][`&str`] back to
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/// [`&str`]. The second way is more idiomatic, however both work to do the
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/// conversion explicitly rather than relying on the implicit conversion.
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///
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/// # Representation
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///
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/// A `String` is made up of three components: a pointer to some bytes, a
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/// length, and a capacity. The pointer points to an internal buffer `String`
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/// uses to store its data. The length is the number of bytes currently stored
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/// in the buffer, and the capacity is the size of the buffer in bytes. As such,
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/// the length will always be less than or equal to the capacity.
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///
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/// This buffer is always stored on the heap.
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///
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/// You can look at these with the [`as_ptr`], [`len`], and [`capacity`]
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/// methods:
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///
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/// ```
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/// use std::mem;
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///
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/// let story = String::from("Once upon a time...");
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///
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// FIXME Update this when vec_into_raw_parts is stabilized
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/// // Prevent automatically dropping the String's data
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/// let mut story = mem::ManuallyDrop::new(story);
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///
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/// let ptr = story.as_mut_ptr();
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/// let len = story.len();
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/// let capacity = story.capacity();
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///
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/// // story has nineteen bytes
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/// assert_eq!(19, len);
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///
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/// // We can re-build a String out of ptr, len, and capacity. This is all
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/// // unsafe because we are responsible for making sure the components are
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/// // valid:
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/// let s = unsafe { String::from_raw_parts(ptr, len, capacity) } ;
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///
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/// assert_eq!(String::from("Once upon a time..."), s);
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/// ```
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///
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/// [`as_ptr`]: #method.as_ptr
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/// [`len`]: #method.len
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/// [`capacity`]: #method.capacity
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///
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/// If a `String` has enough capacity, adding elements to it will not
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/// re-allocate. For example, consider this program:
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///
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/// ```
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/// let mut s = String::new();
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///
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/// println!("{}", s.capacity());
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///
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/// for _ in 0..5 {
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/// s.push_str("hello");
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/// println!("{}", s.capacity());
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/// }
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/// ```
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///
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/// This will output the following:
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///
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/// ```text
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/// 0
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/// 5
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/// 10
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/// 20
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/// 20
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/// 40
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/// ```
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///
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/// At first, we have no memory allocated at all, but as we append to the
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/// string, it increases its capacity appropriately. If we instead use the
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/// [`with_capacity`] method to allocate the correct capacity initially:
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///
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/// ```
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/// let mut s = String::with_capacity(25);
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///
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/// println!("{}", s.capacity());
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///
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/// for _ in 0..5 {
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/// s.push_str("hello");
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/// println!("{}", s.capacity());
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/// }
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/// ```
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///
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/// [`with_capacity`]: #method.with_capacity
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///
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/// We end up with a different output:
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///
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/// ```text
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/// 25
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/// 25
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/// 25
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/// 25
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/// 25
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/// 25
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/// ```
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///
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/// Here, there's no need to allocate more memory inside the loop.
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///
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/// [`&str`]: ../../std/primitive.str.html
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/// [`Deref`]: ../../std/ops/trait.Deref.html
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/// [`as_str()`]: struct.String.html#method.as_str
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#[derive(PartialOrd, Eq, Ord)]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct String {
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vec: Vec<u8>,
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}
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/// A possible error value when converting a `String` from a UTF-8 byte vector.
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///
|
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/// This type is the error type for the [`from_utf8`] method on [`String`]. It
|
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/// is designed in such a way to carefully avoid reallocations: the
|
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/// [`into_bytes`] method will give back the byte vector that was used in the
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/// conversion attempt.
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///
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/// [`from_utf8`]: struct.String.html#method.from_utf8
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/// [`String`]: struct.String.html
|
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/// [`into_bytes`]: struct.FromUtf8Error.html#method.into_bytes
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///
|
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/// The [`Utf8Error`] type provided by [`std::str`] represents an error that may
|
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/// 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`
|
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/// through the [`utf8_error`] method.
|
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///
|
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/// [`Utf8Error`]: ../../std/str/struct.Utf8Error.html
|
||
/// [`std::str`]: ../../std/str/index.html
|
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/// [`u8`]: ../../std/primitive.u8.html
|
||
/// [`&str`]: ../../std/primitive.str.html
|
||
/// [`utf8_error`]: #method.utf8_error
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
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/// // some invalid bytes, in a vector
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/// let bytes = vec![0, 159];
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///
|
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/// let value = String::from_utf8(bytes);
|
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///
|
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/// assert!(value.is_err());
|
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/// assert_eq!(vec![0, 159], value.unwrap_err().into_bytes());
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/// ```
|
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#[stable(feature = "rust1", since = "1.0.0")]
|
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#[derive(Debug)]
|
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pub struct FromUtf8Error {
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bytes: Vec<u8>,
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error: Utf8Error,
|
||
}
|
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|
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/// A possible error value when converting a `String` from a UTF-16 byte slice.
|
||
///
|
||
/// This type is the error type for the [`from_utf16`] method on [`String`].
|
||
///
|
||
/// [`from_utf16`]: struct.String.html#method.from_utf16
|
||
/// [`String`]: struct.String.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// // 𝄞mu<invalid>ic
|
||
/// let v = &[0xD834, 0xDD1E, 0x006d, 0x0075,
|
||
/// 0xD800, 0x0069, 0x0063];
|
||
///
|
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/// assert!(String::from_utf16(v).is_err());
|
||
/// ```
|
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#[stable(feature = "rust1", since = "1.0.0")]
|
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#[derive(Debug)]
|
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pub struct FromUtf16Error(());
|
||
|
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impl String {
|
||
/// 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`] method to prevent excessive
|
||
/// re-allocation.
|
||
///
|
||
/// [`with_capacity`]: #method.with_capacity
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let s = String::new();
|
||
/// ```
|
||
#[inline]
|
||
#[rustc_const_stable(feature = "const_string_new", since = "1.32.0")]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub const fn new() -> String {
|
||
String { vec: Vec::new() }
|
||
}
|
||
|
||
/// 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`] method.
|
||
///
|
||
/// [`new`]: #method.new
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::with_capacity(10);
|
||
///
|
||
/// // 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]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn with_capacity(capacity: usize) -> String {
|
||
String { vec: Vec::with_capacity(capacity) }
|
||
}
|
||
|
||
// HACK(japaric): with cfg(test) the inherent `[T]::to_vec` method, which is
|
||
// required for this method definition, is not available. Since we don't
|
||
// require this method for testing purposes, I'll just stub it
|
||
// NB see the slice::hack module in slice.rs for more information
|
||
#[inline]
|
||
#[cfg(test)]
|
||
pub fn from_str(_: &str) -> String {
|
||
panic!("not available with cfg(test)");
|
||
}
|
||
|
||
/// 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:
|
||
///
|
||
/// ```
|
||
/// // some bytes, in a vector
|
||
/// let sparkle_heart = vec![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:
|
||
///
|
||
/// ```
|
||
/// // some invalid bytes, in a vector
|
||
/// let sparkle_heart = vec![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
|
||
/// [`String`]: struct.String.html
|
||
/// [`u8`]: ../../std/primitive.u8.html
|
||
/// [`Vec<u8>`]: ../../std/vec/struct.Vec.html
|
||
/// [`str::from_utf8`]: ../../std/str/fn.from_utf8.html
|
||
/// [`into_bytes`]: struct.String.html#method.into_bytes
|
||
/// [`FromUtf8Error`]: struct.FromUtf8Error.html
|
||
/// [`Err`]: ../../std/result/enum.Result.html#variant.Err
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn from_utf8(vec: Vec<u8>) -> Result<String, FromUtf8Error> {
|
||
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]`][byteslice]) 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()` will replace any invalid UTF-8 sequences with
|
||
/// [`U+FFFD REPLACEMENT CHARACTER`][U+FFFD], which looks like this: <20>
|
||
///
|
||
/// [`u8`]: ../../std/primitive.u8.html
|
||
/// [byteslice]: ../../std/primitive.slice.html
|
||
/// [U+FFFD]: ../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
|
||
///
|
||
/// This function returns a [`Cow<'a, str>`]. If our byte slice is invalid
|
||
/// UTF-8, then we need to insert the replacement characters, which will
|
||
/// change the size of the string, and hence, require a `String`. But if
|
||
/// it's already valid UTF-8, we don't need a new allocation. This return
|
||
/// type allows us to handle both cases.
|
||
///
|
||
/// [`Cow<'a, str>`]: ../../std/borrow/enum.Cow.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// // some bytes, in a vector
|
||
/// let sparkle_heart = vec![240, 159, 146, 150];
|
||
///
|
||
/// let sparkle_heart = String::from_utf8_lossy(&sparkle_heart);
|
||
///
|
||
/// assert_eq!("💖", sparkle_heart);
|
||
/// ```
|
||
///
|
||
/// Incorrect bytes:
|
||
///
|
||
/// ```
|
||
/// // some invalid bytes
|
||
/// let input = b"Hello \xF0\x90\x80World";
|
||
/// let output = String::from_utf8_lossy(input);
|
||
///
|
||
/// assert_eq!("Hello <20>World", output);
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn from_utf8_lossy(v: &[u8]) -> Cow<'_, str> {
|
||
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());
|
||
return Cow::Borrowed(valid);
|
||
}
|
||
(valid, broken)
|
||
} else {
|
||
return Cow::Borrowed("");
|
||
};
|
||
|
||
const REPLACEMENT: &str = "\u{FFFD}";
|
||
|
||
let mut res = String::with_capacity(v.len());
|
||
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);
|
||
}
|
||
}
|
||
|
||
Cow::Owned(res)
|
||
}
|
||
|
||
/// Decode a UTF-16 encoded vector `v` into a `String`, returning [`Err`]
|
||
/// if `v` contains any invalid data.
|
||
///
|
||
/// [`Err`]: ../../std/result/enum.Result.html#variant.Err
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// // 𝄞music
|
||
/// let v = &[0xD834, 0xDD1E, 0x006d, 0x0075,
|
||
/// 0x0073, 0x0069, 0x0063];
|
||
/// assert_eq!(String::from("𝄞music"),
|
||
/// String::from_utf16(v).unwrap());
|
||
///
|
||
/// // 𝄞mu<invalid>ic
|
||
/// let v = &[0xD834, 0xDD1E, 0x006d, 0x0075,
|
||
/// 0xD800, 0x0069, 0x0063];
|
||
/// assert!(String::from_utf16(v).is_err());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn from_utf16(v: &[u16]) -> Result<String, FromUtf16Error> {
|
||
// This isn't done via collect::<Result<_, _>>() for performance reasons.
|
||
// FIXME: the function can be simplified again when #48994 is closed.
|
||
let mut ret = String::with_capacity(v.len());
|
||
for c in decode_utf16(v.iter().cloned()) {
|
||
if let Ok(c) = c {
|
||
ret.push(c);
|
||
} else {
|
||
return Err(FromUtf16Error(()));
|
||
}
|
||
}
|
||
Ok(ret)
|
||
}
|
||
|
||
/// Decode a UTF-16 encoded slice `v` into a `String`, replacing
|
||
/// invalid data with [the replacement character (`U+FFFD`)][U+FFFD].
|
||
///
|
||
/// Unlike [`from_utf8_lossy`] which returns a [`Cow<'a, str>`],
|
||
/// `from_utf16_lossy` returns a `String` since the UTF-16 to UTF-8
|
||
/// conversion requires a memory allocation.
|
||
///
|
||
/// [`from_utf8_lossy`]: #method.from_utf8_lossy
|
||
/// [`Cow<'a, str>`]: ../borrow/enum.Cow.html
|
||
/// [U+FFFD]: ../char/constant.REPLACEMENT_CHARACTER.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// // 𝄞mus<invalid>ic<invalid>
|
||
/// let v = &[0xD834, 0xDD1E, 0x006d, 0x0075,
|
||
/// 0x0073, 0xDD1E, 0x0069, 0x0063,
|
||
/// 0xD834];
|
||
///
|
||
/// assert_eq!(String::from("𝄞mus\u{FFFD}ic\u{FFFD}"),
|
||
/// String::from_utf16_lossy(v));
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn from_utf16_lossy(v: &[u16]) -> String {
|
||
decode_utf16(v.iter().cloned()).map(|r| r.unwrap_or(REPLACEMENT_CHARACTER)).collect()
|
||
}
|
||
|
||
/// Decomposes a `String` into its raw components.
|
||
///
|
||
/// Returns the raw pointer to the underlying data, the length of
|
||
/// the string (in bytes), and the allocated capacity of the data
|
||
/// (in bytes). These are the same arguments in the same order as
|
||
/// the arguments to [`from_raw_parts`].
|
||
///
|
||
/// After calling this function, the caller is responsible for the
|
||
/// memory previously managed by the `String`. The only way to do
|
||
/// this is to convert the raw pointer, length, and capacity back
|
||
/// into a `String` with the [`from_raw_parts`] function, allowing
|
||
/// the destructor to perform the cleanup.
|
||
///
|
||
/// [`from_raw_parts`]: #method.from_raw_parts
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// #![feature(vec_into_raw_parts)]
|
||
/// let s = String::from("hello");
|
||
///
|
||
/// let (ptr, len, cap) = s.into_raw_parts();
|
||
///
|
||
/// let rebuilt = unsafe { String::from_raw_parts(ptr, len, cap) };
|
||
/// assert_eq!(rebuilt, "hello");
|
||
/// ```
|
||
#[unstable(feature = "vec_into_raw_parts", reason = "new API", issue = "65816")]
|
||
pub fn into_raw_parts(self) -> (*mut u8, usize, usize) {
|
||
self.vec.into_raw_parts()
|
||
}
|
||
|
||
/// 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, with a required alignment of exactly 1.
|
||
/// * `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 std::mem;
|
||
///
|
||
/// unsafe {
|
||
/// let s = String::from("hello");
|
||
///
|
||
// FIXME Update this when vec_into_raw_parts is stabilized
|
||
/// // Prevent automatically dropping the String's data
|
||
/// let mut s = mem::ManuallyDrop::new(s);
|
||
///
|
||
/// let ptr = s.as_mut_ptr();
|
||
/// let len = s.len();
|
||
/// let capacity = s.capacity();
|
||
///
|
||
/// let s = String::from_raw_parts(ptr, len, capacity);
|
||
///
|
||
/// assert_eq!(String::from("hello"), s);
|
||
/// }
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub unsafe fn from_raw_parts(buf: *mut u8, length: usize, capacity: usize) -> String {
|
||
String { vec: Vec::from_raw_parts(buf, length, capacity) }
|
||
}
|
||
|
||
/// 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 the rest of
|
||
/// the standard library assumes that `String`s are valid UTF-8.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// // some bytes, in a vector
|
||
/// let sparkle_heart = vec![240, 159, 146, 150];
|
||
///
|
||
/// let sparkle_heart = unsafe {
|
||
/// String::from_utf8_unchecked(sparkle_heart)
|
||
/// };
|
||
///
|
||
/// assert_eq!("💖", sparkle_heart);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub unsafe fn from_utf8_unchecked(bytes: Vec<u8>) -> String {
|
||
String { vec: bytes }
|
||
}
|
||
|
||
/// Converts a `String` into a byte vector.
|
||
///
|
||
/// This consumes the `String`, so we do not need to copy its contents.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let s = String::from("hello");
|
||
/// let bytes = s.into_bytes();
|
||
///
|
||
/// assert_eq!(&[104, 101, 108, 108, 111][..], &bytes[..]);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn into_bytes(self) -> Vec<u8> {
|
||
self.vec
|
||
}
|
||
|
||
/// Extracts a string slice containing the entire `String`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let s = String::from("foo");
|
||
///
|
||
/// assert_eq!("foo", s.as_str());
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "string_as_str", since = "1.7.0")]
|
||
pub fn as_str(&self) -> &str {
|
||
self
|
||
}
|
||
|
||
/// Converts a `String` into a mutable string slice.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("foobar");
|
||
/// let s_mut_str = s.as_mut_str();
|
||
///
|
||
/// s_mut_str.make_ascii_uppercase();
|
||
///
|
||
/// assert_eq!("FOOBAR", s_mut_str);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "string_as_str", since = "1.7.0")]
|
||
pub fn as_mut_str(&mut self) -> &mut str {
|
||
self
|
||
}
|
||
|
||
/// Appends a given string slice onto the end of this `String`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("foo");
|
||
///
|
||
/// s.push_str("bar");
|
||
///
|
||
/// assert_eq!("foobar", s);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
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:
|
||
///
|
||
/// ```
|
||
/// let s = String::with_capacity(10);
|
||
///
|
||
/// assert!(s.capacity() >= 10);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
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`]: ../../std/primitive.usize.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::new();
|
||
///
|
||
/// s.reserve(10);
|
||
///
|
||
/// assert!(s.capacity() >= 10);
|
||
/// ```
|
||
///
|
||
/// This may not actually increase the capacity:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::with_capacity(10);
|
||
/// 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]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
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:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::new();
|
||
///
|
||
/// s.reserve_exact(10);
|
||
///
|
||
/// assert!(s.capacity() >= 10);
|
||
/// ```
|
||
///
|
||
/// This may not actually increase the capacity:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::with_capacity(10);
|
||
/// 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]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn reserve_exact(&mut self, additional: usize) {
|
||
self.vec.reserve_exact(additional)
|
||
}
|
||
|
||
/// Tries to reserve capacity for at least `additional` more elements to be inserted
|
||
/// in the given `String`. The collection may reserve more space to avoid
|
||
/// frequent reallocations. After calling `reserve`, capacity will be
|
||
/// greater than or equal to `self.len() + additional`. Does nothing if
|
||
/// capacity is already sufficient.
|
||
///
|
||
/// # Errors
|
||
///
|
||
/// If the capacity overflows, or the allocator reports a failure, then an error
|
||
/// is returned.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// #![feature(try_reserve)]
|
||
/// use std::collections::TryReserveError;
|
||
///
|
||
/// fn process_data(data: &str) -> Result<String, TryReserveError> {
|
||
/// let mut output = String::new();
|
||
///
|
||
/// // Pre-reserve the memory, exiting if we can't
|
||
/// output.try_reserve(data.len())?;
|
||
///
|
||
/// // Now we know this can't OOM in the middle of our complex work
|
||
/// output.push_str(data);
|
||
///
|
||
/// Ok(output)
|
||
/// }
|
||
/// # process_data("rust").expect("why is the test harness OOMing on 4 bytes?");
|
||
/// ```
|
||
#[unstable(feature = "try_reserve", reason = "new API", issue = "48043")]
|
||
pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> {
|
||
self.vec.try_reserve(additional)
|
||
}
|
||
|
||
/// Tries to reserves the minimum capacity for exactly `additional` more elements to
|
||
/// be inserted in the given `String`. After calling `reserve_exact`,
|
||
/// capacity will be greater than or equal to `self.len() + additional`.
|
||
/// Does nothing if the capacity is already sufficient.
|
||
///
|
||
/// Note that the allocator may give the collection more space than it
|
||
/// requests. Therefore, capacity can not be relied upon to be precisely
|
||
/// minimal. Prefer `reserve` if future insertions are expected.
|
||
///
|
||
/// # Errors
|
||
///
|
||
/// If the capacity overflows, or the allocator reports a failure, then an error
|
||
/// is returned.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// #![feature(try_reserve)]
|
||
/// use std::collections::TryReserveError;
|
||
///
|
||
/// fn process_data(data: &str) -> Result<String, TryReserveError> {
|
||
/// let mut output = String::new();
|
||
///
|
||
/// // Pre-reserve the memory, exiting if we can't
|
||
/// output.try_reserve(data.len())?;
|
||
///
|
||
/// // Now we know this can't OOM in the middle of our complex work
|
||
/// output.push_str(data);
|
||
///
|
||
/// Ok(output)
|
||
/// }
|
||
/// # process_data("rust").expect("why is the test harness OOMing on 4 bytes?");
|
||
/// ```
|
||
#[unstable(feature = "try_reserve", reason = "new API", issue = "48043")]
|
||
pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), TryReserveError> {
|
||
self.vec.try_reserve_exact(additional)
|
||
}
|
||
|
||
/// Shrinks the capacity of this `String` to match its length.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("foo");
|
||
///
|
||
/// s.reserve(100);
|
||
/// assert!(s.capacity() >= 100);
|
||
///
|
||
/// s.shrink_to_fit();
|
||
/// assert_eq!(3, s.capacity());
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn shrink_to_fit(&mut self) {
|
||
self.vec.shrink_to_fit()
|
||
}
|
||
|
||
/// Shrinks the capacity of this `String` with a lower bound.
|
||
///
|
||
/// The capacity will remain at least as large as both the length
|
||
/// and the supplied value.
|
||
///
|
||
/// Panics if the current capacity is smaller than the supplied
|
||
/// minimum capacity.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// #![feature(shrink_to)]
|
||
/// let mut s = String::from("foo");
|
||
///
|
||
/// s.reserve(100);
|
||
/// assert!(s.capacity() >= 100);
|
||
///
|
||
/// s.shrink_to(10);
|
||
/// assert!(s.capacity() >= 10);
|
||
/// s.shrink_to(0);
|
||
/// assert!(s.capacity() >= 3);
|
||
/// ```
|
||
#[inline]
|
||
#[unstable(feature = "shrink_to", reason = "new API", issue = "56431")]
|
||
pub fn shrink_to(&mut self, min_capacity: usize) {
|
||
self.vec.shrink_to(min_capacity)
|
||
}
|
||
|
||
/// Appends the given [`char`] to the end of this `String`.
|
||
///
|
||
/// [`char`]: ../../std/primitive.char.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("abc");
|
||
///
|
||
/// s.push('1');
|
||
/// s.push('2');
|
||
/// s.push('3');
|
||
///
|
||
/// assert_eq!("abc123", s);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
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:
|
||
///
|
||
/// ```
|
||
/// let s = String::from("hello");
|
||
///
|
||
/// assert_eq!(&[104, 101, 108, 108, 111], s.as_bytes());
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
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`]: ../../std/primitive.char.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("hello");
|
||
///
|
||
/// s.truncate(2);
|
||
///
|
||
/// assert_eq!("he", s);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
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`]: ../../std/option/enum.Option.html#variant.None
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("foo");
|
||
///
|
||
/// assert_eq!(s.pop(), Some('o'));
|
||
/// assert_eq!(s.pop(), Some('o'));
|
||
/// assert_eq!(s.pop(), Some('f'));
|
||
///
|
||
/// assert_eq!(s.pop(), None);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
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`]: ../../std/primitive.char.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("foo");
|
||
///
|
||
/// assert_eq!(s.remove(0), 'f');
|
||
/// assert_eq!(s.remove(1), 'o');
|
||
/// assert_eq!(s.remove(0), 'o');
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
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, visiting each character exactly once in the
|
||
/// original order, and preserves the order of the retained characters.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("f_o_ob_ar");
|
||
///
|
||
/// s.retain(|c| c != '_');
|
||
///
|
||
/// assert_eq!(s, "foobar");
|
||
/// ```
|
||
///
|
||
/// The exact order may be useful for tracking external state, like an index.
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("abcde");
|
||
/// let keep = [false, true, true, false, true];
|
||
/// let mut i = 0;
|
||
/// s.retain(|_| (keep[i], i += 1).0);
|
||
/// assert_eq!(s, "bce");
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "string_retain", since = "1.26.0")]
|
||
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`]: ../../std/primitive.char.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::with_capacity(3);
|
||
///
|
||
/// s.insert(0, 'f');
|
||
/// s.insert(1, 'o');
|
||
/// s.insert(2, 'o');
|
||
///
|
||
/// assert_eq!("foo", s);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
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`]: ../../std/primitive.char.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("bar");
|
||
///
|
||
/// s.insert_str(0, "foo");
|
||
///
|
||
/// assert_eq!("foobar", s);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "insert_str", since = "1.16.0")]
|
||
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 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 the rest of
|
||
/// the standard library assumes that `String`s are valid UTF-8.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("hello");
|
||
///
|
||
/// unsafe {
|
||
/// let vec = s.as_mut_vec();
|
||
/// assert_eq!(&[104, 101, 108, 108, 111][..], &vec[..]);
|
||
///
|
||
/// vec.reverse();
|
||
/// }
|
||
/// assert_eq!(s, "olleh");
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub unsafe fn as_mut_vec(&mut self) -> &mut Vec<u8> {
|
||
&mut self.vec
|
||
}
|
||
|
||
/// Returns the length of this `String`, in bytes, not [`char`]s or
|
||
/// graphemes. In other words, it may not be what a human considers the
|
||
/// length of the string.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let a = String::from("foo");
|
||
/// assert_eq!(a.len(), 3);
|
||
///
|
||
/// let fancy_f = String::from("ƒoo");
|
||
/// assert_eq!(fancy_f.len(), 4);
|
||
/// assert_eq!(fancy_f.chars().count(), 3);
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn len(&self) -> usize {
|
||
self.vec.len()
|
||
}
|
||
|
||
/// Returns `true` if this `String` has a length of zero, and `false` otherwise.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut v = String::new();
|
||
/// assert!(v.is_empty());
|
||
///
|
||
/// v.push('a');
|
||
/// assert!(!v.is_empty());
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
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
|
||
///
|
||
/// ```
|
||
/// # fn main() {
|
||
/// let mut hello = String::from("Hello, World!");
|
||
/// let world = hello.split_off(7);
|
||
/// assert_eq!(hello, "Hello, ");
|
||
/// assert_eq!(world, "World!");
|
||
/// # }
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "string_split_off", since = "1.16.0")]
|
||
pub fn split_off(&mut self, at: usize) -> String {
|
||
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:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("foo");
|
||
///
|
||
/// s.clear();
|
||
///
|
||
/// assert!(s.is_empty());
|
||
/// assert_eq!(0, s.len());
|
||
/// assert_eq!(3, s.capacity());
|
||
/// ```
|
||
#[inline]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
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`]: ../../std/primitive.char.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("α is alpha, β is beta");
|
||
/// let beta_offset = s.find('β').unwrap_or(s.len());
|
||
///
|
||
/// // Remove the range up until the β from the string
|
||
/// let t: String = s.drain(..beta_offset).collect();
|
||
/// assert_eq!(t, "α is alpha, ");
|
||
/// assert_eq!(s, "β is beta");
|
||
///
|
||
/// // A full range clears the string
|
||
/// s.drain(..);
|
||
/// assert_eq!(s, "");
|
||
/// ```
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
pub fn drain<R>(&mut self, range: R) -> Drain<'_>
|
||
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`]: ../../std/primitive.char.html
|
||
/// [`Vec::splice`]: ../../std/vec/struct.Vec.html#method.splice
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let mut s = String::from("α is alpha, β is beta");
|
||
/// 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");
|
||
/// ```
|
||
#[stable(feature = "splice", since = "1.27.0")]
|
||
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());
|
||
}
|
||
|
||
/// Converts this `String` into a [`Box`]`<`[`str`]`>`.
|
||
///
|
||
/// This will drop any excess capacity.
|
||
///
|
||
/// [`Box`]: ../../std/boxed/struct.Box.html
|
||
/// [`str`]: ../../std/primitive.str.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let s = String::from("hello");
|
||
///
|
||
/// let b = s.into_boxed_str();
|
||
/// ```
|
||
#[stable(feature = "box_str", since = "1.4.0")]
|
||
#[inline]
|
||
pub fn into_boxed_str(self) -> Box<str> {
|
||
let slice = self.vec.into_boxed_slice();
|
||
unsafe { from_boxed_utf8_unchecked(slice) }
|
||
}
|
||
}
|
||
|
||
impl FromUtf8Error {
|
||
/// Returns a slice of [`u8`]s bytes that were attempted to convert to a `String`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// // some invalid bytes, in a vector
|
||
/// let bytes = vec![0, 159];
|
||
///
|
||
/// let value = String::from_utf8(bytes);
|
||
///
|
||
/// assert_eq!(&[0, 159], value.unwrap_err().as_bytes());
|
||
/// ```
|
||
#[stable(feature = "from_utf8_error_as_bytes", since = "1.26.0")]
|
||
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:
|
||
///
|
||
/// ```
|
||
/// // some invalid bytes, in a vector
|
||
/// let bytes = vec![0, 159];
|
||
///
|
||
/// let value = String::from_utf8(bytes);
|
||
///
|
||
/// assert_eq!(vec![0, 159], value.unwrap_err().into_bytes());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn into_bytes(self) -> Vec<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`]: ../../std/str/struct.Utf8Error.html
|
||
/// [`std::str`]: ../../std/str/index.html
|
||
/// [`u8`]: ../../std/primitive.u8.html
|
||
/// [`&str`]: ../../std/primitive.str.html
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// // some invalid bytes, in a vector
|
||
/// let bytes = vec![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());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub fn utf8_error(&self) -> Utf8Error {
|
||
self.error
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl fmt::Display for FromUtf8Error {
|
||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
fmt::Display::fmt(&self.error, f)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl fmt::Display for FromUtf16Error {
|
||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
fmt::Display::fmt("invalid utf-16: lone surrogate found", f)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl Clone for String {
|
||
fn clone(&self) -> Self {
|
||
String { vec: self.vec.clone() }
|
||
}
|
||
|
||
fn clone_from(&mut self, source: &Self) {
|
||
self.vec.clone_from(&source.vec);
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl FromIterator<char> for String {
|
||
fn from_iter<I: IntoIterator<Item = char>>(iter: I) -> String {
|
||
let mut buf = String::new();
|
||
buf.extend(iter);
|
||
buf
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "string_from_iter_by_ref", since = "1.17.0")]
|
||
impl<'a> FromIterator<&'a char> for String {
|
||
fn from_iter<I: IntoIterator<Item = &'a char>>(iter: I) -> String {
|
||
let mut buf = String::new();
|
||
buf.extend(iter);
|
||
buf
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<'a> FromIterator<&'a str> for String {
|
||
fn from_iter<I: IntoIterator<Item = &'a str>>(iter: I) -> String {
|
||
let mut buf = String::new();
|
||
buf.extend(iter);
|
||
buf
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "extend_string", since = "1.4.0")]
|
||
impl FromIterator<String> for String {
|
||
fn from_iter<I: IntoIterator<Item = String>>(iter: I) -> String {
|
||
let mut iterator = iter.into_iter();
|
||
|
||
// Because we're iterating over `String`s, we can avoid at least
|
||
// one allocation by getting the first string from the iterator
|
||
// and appending to it all the subsequent strings.
|
||
match iterator.next() {
|
||
None => String::new(),
|
||
Some(mut buf) => {
|
||
buf.extend(iterator);
|
||
buf
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "herd_cows", since = "1.19.0")]
|
||
impl<'a> FromIterator<Cow<'a, str>> for String {
|
||
fn from_iter<I: IntoIterator<Item = Cow<'a, str>>>(iter: I) -> String {
|
||
let mut iterator = iter.into_iter();
|
||
|
||
// Because we're iterating over CoWs, we can (potentially) avoid at least
|
||
// one allocation by getting the first item and appending to it all the
|
||
// subsequent items.
|
||
match iterator.next() {
|
||
None => String::new(),
|
||
Some(cow) => {
|
||
let mut buf = cow.into_owned();
|
||
buf.extend(iterator);
|
||
buf
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl Extend<char> for String {
|
||
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);
|
||
iterator.for_each(move |c| self.push(c));
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "extend_ref", since = "1.2.0")]
|
||
impl<'a> Extend<&'a char> for String {
|
||
fn extend<I: IntoIterator<Item = &'a char>>(&mut self, iter: I) {
|
||
self.extend(iter.into_iter().cloned());
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<'a> Extend<&'a str> for String {
|
||
fn extend<I: IntoIterator<Item = &'a str>>(&mut self, iter: I) {
|
||
iter.into_iter().for_each(move |s| self.push_str(s));
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "extend_string", since = "1.4.0")]
|
||
impl Extend<String> for String {
|
||
fn extend<I: IntoIterator<Item = String>>(&mut self, iter: I) {
|
||
iter.into_iter().for_each(move |s| self.push_str(&s));
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "herd_cows", since = "1.19.0")]
|
||
impl<'a> Extend<Cow<'a, str>> for String {
|
||
fn extend<I: IntoIterator<Item = Cow<'a, str>>>(&mut self, iter: I) {
|
||
iter.into_iter().for_each(move |s| self.push_str(&s));
|
||
}
|
||
}
|
||
|
||
/// A convenience impl that delegates to the impl for `&str`
|
||
#[unstable(
|
||
feature = "pattern",
|
||
reason = "API not fully fleshed out and ready to be stabilized",
|
||
issue = "27721"
|
||
)]
|
||
impl<'a, 'b> Pattern<'a> for &'b String {
|
||
type Searcher = <&'b str as Pattern<'a>>::Searcher;
|
||
|
||
fn into_searcher(self, haystack: &'a str) -> <&'b str as Pattern<'a>>::Searcher {
|
||
self[..].into_searcher(haystack)
|
||
}
|
||
|
||
#[inline]
|
||
fn is_contained_in(self, haystack: &'a str) -> bool {
|
||
self[..].is_contained_in(haystack)
|
||
}
|
||
|
||
#[inline]
|
||
fn is_prefix_of(self, haystack: &'a str) -> bool {
|
||
self[..].is_prefix_of(haystack)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl PartialEq for String {
|
||
#[inline]
|
||
fn eq(&self, other: &String) -> bool {
|
||
PartialEq::eq(&self[..], &other[..])
|
||
}
|
||
#[inline]
|
||
fn ne(&self, other: &String) -> bool {
|
||
PartialEq::ne(&self[..], &other[..])
|
||
}
|
||
}
|
||
|
||
macro_rules! impl_eq {
|
||
($lhs:ty, $rhs: ty) => {
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[allow(unused_lifetimes)]
|
||
impl<'a, 'b> PartialEq<$rhs> for $lhs {
|
||
#[inline]
|
||
fn eq(&self, other: &$rhs) -> bool {
|
||
PartialEq::eq(&self[..], &other[..])
|
||
}
|
||
#[inline]
|
||
fn ne(&self, other: &$rhs) -> bool {
|
||
PartialEq::ne(&self[..], &other[..])
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[allow(unused_lifetimes)]
|
||
impl<'a, 'b> PartialEq<$lhs> for $rhs {
|
||
#[inline]
|
||
fn eq(&self, other: &$lhs) -> bool {
|
||
PartialEq::eq(&self[..], &other[..])
|
||
}
|
||
#[inline]
|
||
fn ne(&self, other: &$lhs) -> bool {
|
||
PartialEq::ne(&self[..], &other[..])
|
||
}
|
||
}
|
||
};
|
||
}
|
||
|
||
impl_eq! { String, str }
|
||
impl_eq! { String, &'a str }
|
||
impl_eq! { Cow<'a, str>, str }
|
||
impl_eq! { Cow<'a, str>, &'b str }
|
||
impl_eq! { Cow<'a, str>, String }
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl Default for String {
|
||
/// Creates an empty `String`.
|
||
#[inline]
|
||
fn default() -> String {
|
||
String::new()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl fmt::Display for String {
|
||
#[inline]
|
||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
fmt::Display::fmt(&**self, f)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl fmt::Debug for String {
|
||
#[inline]
|
||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
fmt::Debug::fmt(&**self, f)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl hash::Hash for String {
|
||
#[inline]
|
||
fn hash<H: hash::Hasher>(&self, hasher: &mut H) {
|
||
(**self).hash(hasher)
|
||
}
|
||
}
|
||
|
||
/// Implements the `+` operator for concatenating two strings.
|
||
///
|
||
/// This consumes the `String` on the left-hand side and re-uses its buffer (growing it if
|
||
/// necessary). This is done to avoid allocating a new `String` 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`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Concatenating two `String`s takes the first by value and borrows the second:
|
||
///
|
||
/// ```
|
||
/// let a = String::from("hello");
|
||
/// let b = String::from(" world");
|
||
/// 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:
|
||
///
|
||
/// ```
|
||
/// let a = String::from("hello");
|
||
/// let b = String::from(" world");
|
||
/// let c = a.clone() + &b;
|
||
/// // `a` is still valid here.
|
||
/// ```
|
||
///
|
||
/// Concatenating `&str` slices can be done by converting the first to a `String`:
|
||
///
|
||
/// ```
|
||
/// let a = "hello";
|
||
/// let b = " world";
|
||
/// let c = a.to_string() + b;
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl Add<&str> for String {
|
||
type Output = String;
|
||
|
||
#[inline]
|
||
fn add(mut self, other: &str) -> String {
|
||
self.push_str(other);
|
||
self
|
||
}
|
||
}
|
||
|
||
/// Implements the `+=` operator for appending to a `String`.
|
||
///
|
||
/// This has the same behavior as the [`push_str`][String::push_str] method.
|
||
#[stable(feature = "stringaddassign", since = "1.12.0")]
|
||
impl AddAssign<&str> for String {
|
||
#[inline]
|
||
fn add_assign(&mut self, other: &str) {
|
||
self.push_str(other);
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl ops::Index<ops::Range<usize>> for String {
|
||
type Output = str;
|
||
|
||
#[inline]
|
||
fn index(&self, index: ops::Range<usize>) -> &str {
|
||
&self[..][index]
|
||
}
|
||
}
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl ops::Index<ops::RangeTo<usize>> for String {
|
||
type Output = str;
|
||
|
||
#[inline]
|
||
fn index(&self, index: ops::RangeTo<usize>) -> &str {
|
||
&self[..][index]
|
||
}
|
||
}
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl ops::Index<ops::RangeFrom<usize>> for String {
|
||
type Output = str;
|
||
|
||
#[inline]
|
||
fn index(&self, index: ops::RangeFrom<usize>) -> &str {
|
||
&self[..][index]
|
||
}
|
||
}
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl ops::Index<ops::RangeFull> for String {
|
||
type Output = str;
|
||
|
||
#[inline]
|
||
fn index(&self, _index: ops::RangeFull) -> &str {
|
||
unsafe { str::from_utf8_unchecked(&self.vec) }
|
||
}
|
||
}
|
||
#[stable(feature = "inclusive_range", since = "1.26.0")]
|
||
impl ops::Index<ops::RangeInclusive<usize>> for String {
|
||
type Output = str;
|
||
|
||
#[inline]
|
||
fn index(&self, index: ops::RangeInclusive<usize>) -> &str {
|
||
Index::index(&**self, index)
|
||
}
|
||
}
|
||
#[stable(feature = "inclusive_range", since = "1.26.0")]
|
||
impl ops::Index<ops::RangeToInclusive<usize>> for String {
|
||
type Output = str;
|
||
|
||
#[inline]
|
||
fn index(&self, index: ops::RangeToInclusive<usize>) -> &str {
|
||
Index::index(&**self, index)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "derefmut_for_string", since = "1.3.0")]
|
||
impl ops::IndexMut<ops::Range<usize>> for String {
|
||
#[inline]
|
||
fn index_mut(&mut self, index: ops::Range<usize>) -> &mut str {
|
||
&mut self[..][index]
|
||
}
|
||
}
|
||
#[stable(feature = "derefmut_for_string", since = "1.3.0")]
|
||
impl ops::IndexMut<ops::RangeTo<usize>> for String {
|
||
#[inline]
|
||
fn index_mut(&mut self, index: ops::RangeTo<usize>) -> &mut str {
|
||
&mut self[..][index]
|
||
}
|
||
}
|
||
#[stable(feature = "derefmut_for_string", since = "1.3.0")]
|
||
impl ops::IndexMut<ops::RangeFrom<usize>> for String {
|
||
#[inline]
|
||
fn index_mut(&mut self, index: ops::RangeFrom<usize>) -> &mut str {
|
||
&mut self[..][index]
|
||
}
|
||
}
|
||
#[stable(feature = "derefmut_for_string", since = "1.3.0")]
|
||
impl ops::IndexMut<ops::RangeFull> for String {
|
||
#[inline]
|
||
fn index_mut(&mut self, _index: ops::RangeFull) -> &mut str {
|
||
unsafe { str::from_utf8_unchecked_mut(&mut *self.vec) }
|
||
}
|
||
}
|
||
#[stable(feature = "inclusive_range", since = "1.26.0")]
|
||
impl ops::IndexMut<ops::RangeInclusive<usize>> for String {
|
||
#[inline]
|
||
fn index_mut(&mut self, index: ops::RangeInclusive<usize>) -> &mut str {
|
||
IndexMut::index_mut(&mut **self, index)
|
||
}
|
||
}
|
||
#[stable(feature = "inclusive_range", since = "1.26.0")]
|
||
impl ops::IndexMut<ops::RangeToInclusive<usize>> for String {
|
||
#[inline]
|
||
fn index_mut(&mut self, index: ops::RangeToInclusive<usize>) -> &mut str {
|
||
IndexMut::index_mut(&mut **self, index)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl ops::Deref for String {
|
||
type Target = str;
|
||
|
||
#[inline]
|
||
fn deref(&self) -> &str {
|
||
unsafe { str::from_utf8_unchecked(&self.vec) }
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "derefmut_for_string", since = "1.3.0")]
|
||
impl ops::DerefMut for String {
|
||
#[inline]
|
||
fn deref_mut(&mut self) -> &mut str {
|
||
unsafe { str::from_utf8_unchecked_mut(&mut *self.vec) }
|
||
}
|
||
}
|
||
|
||
/// An error when parsing a `String`.
|
||
///
|
||
/// This `enum` is slightly awkward: it will never actually exist. This error is
|
||
/// part of the type signature of the implementation of [`FromStr`] on
|
||
/// [`String`]. The return type of [`from_str`], requires that an error be
|
||
/// defined, but, given that a [`String`] can always be made into a new
|
||
/// [`String`] without error, this type will never actually be returned. As
|
||
/// such, it is only here to satisfy said signature, and is useless otherwise.
|
||
///
|
||
/// [`FromStr`]: ../../std/str/trait.FromStr.html
|
||
/// [`String`]: struct.String.html
|
||
/// [`from_str`]: ../../std/str/trait.FromStr.html#tymethod.from_str
|
||
#[stable(feature = "str_parse_error", since = "1.5.0")]
|
||
pub type ParseError = core::convert::Infallible;
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl FromStr for String {
|
||
type Err = core::convert::Infallible;
|
||
#[inline]
|
||
fn from_str(s: &str) -> Result<String, ParseError> {
|
||
Ok(String::from(s))
|
||
}
|
||
}
|
||
|
||
/// A trait for converting a value to a `String`.
|
||
///
|
||
/// This trait is automatically implemented for any type which implements the
|
||
/// [`Display`] trait. As such, `ToString` shouldn't be implemented directly:
|
||
/// [`Display`] should be implemented instead, and you get the `ToString`
|
||
/// implementation for free.
|
||
///
|
||
/// [`Display`]: ../../std/fmt/trait.Display.html
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
pub trait ToString {
|
||
/// Converts the given value to a `String`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let i = 5;
|
||
/// let five = String::from("5");
|
||
///
|
||
/// assert_eq!(five, i.to_string());
|
||
/// ```
|
||
#[rustc_conversion_suggestion]
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
fn to_string(&self) -> String;
|
||
}
|
||
|
||
/// # Panics
|
||
///
|
||
/// In this implementation, the `to_string` method panics
|
||
/// if the `Display` implementation returns an error.
|
||
/// This indicates an incorrect `Display` implementation
|
||
/// since `fmt::Write for String` never returns an error itself.
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<T: fmt::Display + ?Sized> ToString for T {
|
||
#[inline]
|
||
default fn to_string(&self) -> String {
|
||
use fmt::Write;
|
||
let mut buf = String::new();
|
||
buf.write_fmt(format_args!("{}", self))
|
||
.expect("a Display implementation returned an error unexpectedly");
|
||
buf.shrink_to_fit();
|
||
buf
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "str_to_string_specialization", since = "1.9.0")]
|
||
impl ToString for str {
|
||
#[inline]
|
||
fn to_string(&self) -> String {
|
||
String::from(self)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "cow_str_to_string_specialization", since = "1.17.0")]
|
||
impl ToString for Cow<'_, str> {
|
||
#[inline]
|
||
fn to_string(&self) -> String {
|
||
self[..].to_owned()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "string_to_string_specialization", since = "1.17.0")]
|
||
impl ToString for String {
|
||
#[inline]
|
||
fn to_string(&self) -> String {
|
||
self.to_owned()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl AsRef<str> for String {
|
||
#[inline]
|
||
fn as_ref(&self) -> &str {
|
||
self
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl AsRef<[u8]> for String {
|
||
#[inline]
|
||
fn as_ref(&self) -> &[u8] {
|
||
self.as_bytes()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl From<&str> for String {
|
||
#[inline]
|
||
fn from(s: &str) -> String {
|
||
s.to_owned()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "from_ref_string", since = "1.35.0")]
|
||
impl From<&String> for String {
|
||
#[inline]
|
||
fn from(s: &String) -> String {
|
||
s.clone()
|
||
}
|
||
}
|
||
|
||
// note: test pulls in libstd, which causes errors here
|
||
#[cfg(not(test))]
|
||
#[stable(feature = "string_from_box", since = "1.18.0")]
|
||
impl From<Box<str>> for String {
|
||
/// Converts the given boxed `str` slice to a `String`.
|
||
/// It is notable that the `str` slice is owned.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let s1: String = String::from("hello world");
|
||
/// let s2: Box<str> = s1.into_boxed_str();
|
||
/// let s3: String = String::from(s2);
|
||
///
|
||
/// assert_eq!("hello world", s3)
|
||
/// ```
|
||
fn from(s: Box<str>) -> String {
|
||
s.into_string()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "box_from_str", since = "1.20.0")]
|
||
impl From<String> for Box<str> {
|
||
/// Converts the given `String` to a boxed `str` slice that is owned.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let s1: String = String::from("hello world");
|
||
/// let s2: Box<str> = Box::from(s1);
|
||
/// let s3: String = String::from(s2);
|
||
///
|
||
/// assert_eq!("hello world", s3)
|
||
/// ```
|
||
fn from(s: String) -> Box<str> {
|
||
s.into_boxed_str()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "string_from_cow_str", since = "1.14.0")]
|
||
impl<'a> From<Cow<'a, str>> for String {
|
||
fn from(s: Cow<'a, str>) -> String {
|
||
s.into_owned()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<'a> From<&'a str> for Cow<'a, str> {
|
||
#[inline]
|
||
fn from(s: &'a str) -> Cow<'a, str> {
|
||
Cow::Borrowed(s)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl<'a> From<String> for Cow<'a, str> {
|
||
#[inline]
|
||
fn from(s: String) -> Cow<'a, str> {
|
||
Cow::Owned(s)
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "cow_from_string_ref", since = "1.28.0")]
|
||
impl<'a> From<&'a String> for Cow<'a, str> {
|
||
#[inline]
|
||
fn from(s: &'a String) -> Cow<'a, str> {
|
||
Cow::Borrowed(s.as_str())
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "cow_str_from_iter", since = "1.12.0")]
|
||
impl<'a> FromIterator<char> for Cow<'a, str> {
|
||
fn from_iter<I: IntoIterator<Item = char>>(it: I) -> Cow<'a, str> {
|
||
Cow::Owned(FromIterator::from_iter(it))
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "cow_str_from_iter", since = "1.12.0")]
|
||
impl<'a, 'b> FromIterator<&'b str> for Cow<'a, str> {
|
||
fn from_iter<I: IntoIterator<Item = &'b str>>(it: I) -> Cow<'a, str> {
|
||
Cow::Owned(FromIterator::from_iter(it))
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "cow_str_from_iter", since = "1.12.0")]
|
||
impl<'a> FromIterator<String> for Cow<'a, str> {
|
||
fn from_iter<I: IntoIterator<Item = String>>(it: I) -> Cow<'a, str> {
|
||
Cow::Owned(FromIterator::from_iter(it))
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "from_string_for_vec_u8", since = "1.14.0")]
|
||
impl From<String> for Vec<u8> {
|
||
/// Converts the given `String` to a vector `Vec` that holds values of type `u8`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let s1 = String::from("hello world");
|
||
/// let v1 = Vec::from(s1);
|
||
///
|
||
/// for b in v1 {
|
||
/// println!("{}", b);
|
||
/// }
|
||
/// ```
|
||
fn from(string: String) -> Vec<u8> {
|
||
string.into_bytes()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
impl fmt::Write for String {
|
||
#[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(())
|
||
}
|
||
}
|
||
|
||
/// A draining iterator for `String`.
|
||
///
|
||
/// This struct is created by the [`drain`] method on [`String`]. See its
|
||
/// documentation for more.
|
||
///
|
||
/// [`drain`]: struct.String.html#method.drain
|
||
/// [`String`]: struct.String.html
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
pub struct Drain<'a> {
|
||
/// Will be used as &'a mut String in the destructor
|
||
string: *mut String,
|
||
/// Start of part to remove
|
||
start: usize,
|
||
/// End of part to remove
|
||
end: usize,
|
||
/// Current remaining range to remove
|
||
iter: Chars<'a>,
|
||
}
|
||
|
||
#[stable(feature = "collection_debug", since = "1.17.0")]
|
||
impl fmt::Debug for Drain<'_> {
|
||
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
||
f.pad("Drain { .. }")
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
unsafe impl Sync for Drain<'_> {}
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
unsafe impl Send for Drain<'_> {}
|
||
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
impl Drop for Drain<'_> {
|
||
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);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
impl Iterator for Drain<'_> {
|
||
type Item = char;
|
||
|
||
#[inline]
|
||
fn next(&mut self) -> Option<char> {
|
||
self.iter.next()
|
||
}
|
||
|
||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||
self.iter.size_hint()
|
||
}
|
||
|
||
#[inline]
|
||
fn last(mut self) -> Option<char> {
|
||
self.next_back()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "drain", since = "1.6.0")]
|
||
impl DoubleEndedIterator for Drain<'_> {
|
||
#[inline]
|
||
fn next_back(&mut self) -> Option<char> {
|
||
self.iter.next_back()
|
||
}
|
||
}
|
||
|
||
#[stable(feature = "fused", since = "1.26.0")]
|
||
impl FusedIterator for Drain<'_> {}
|