| // 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, a trait for converting |
| //! [`ToString`]s, and several error types that may result from working with |
| //! [`String`]s. |
| //! |
| //! [`String`]: struct.String.html |
| //! [`ToString`]: trait.ToString.html |
| //! |
| //! # Examples |
| //! |
| //! There are multiple ways to create a new `String` from a string literal: |
| //! |
| //! ```rust |
| //! let s = "Hello".to_string(); |
| //! |
| //! let s = String::from("world"); |
| //! let s: String = "also this".into(); |
| //! ``` |
| //! |
| //! You can create a new `String` from an existing one by concatenating with |
| //! `+`: |
| //! |
| //! ```rust |
| //! let s = "Hello".to_string(); |
| //! |
| //! let message = s + " world!"; |
| //! ``` |
| //! |
| //! If you have a vector of valid UTF-8 bytes, you can make a `String` out of |
| //! it. You can do the reverse too. |
| //! |
| //! ```rust |
| //! 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); |
| //! |
| //! let bytes = sparkle_heart.into_bytes(); |
| //! |
| //! assert_eq!(bytes, [240, 159, 146, 150]); |
| //! ``` |
| |
| #![stable(feature = "rust1", since = "1.0.0")] |
| |
| use core::fmt; |
| use core::hash; |
| use core::iter::FromIterator; |
| use core::mem; |
| use core::ops::{self, Add, AddAssign, Index, IndexMut}; |
| use core::ptr; |
| use core::str::pattern::Pattern; |
| use rustc_unicode::char::{decode_utf16, REPLACEMENT_CHARACTER}; |
| use rustc_unicode::str as unicode_str; |
| |
| use borrow::{Cow, ToOwned}; |
| use range::RangeArgument; |
| use str::{self, FromStr, Utf8Error, Chars}; |
| use vec::Vec; |
| use boxed::Box; |
| |
| /// 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`]: ../../std/primitive.str.html |
| /// |
| /// # Examples |
| /// |
| /// You can create a `String` from a literal string with `String::from`: |
| /// |
| /// ``` |
| /// let hello = String::from("Hello, world!"); |
| /// ``` |
| /// |
| /// You can append a [`char`] to a `String` with the [`push()`] method, and |
| /// append a [`&str`] with the [`push_str()`] method: |
| /// |
| /// ``` |
| /// let mut hello = String::from("Hello, "); |
| /// |
| /// hello.push('w'); |
| /// hello.push_str("orld!"); |
| /// ``` |
| /// |
| /// [`char`]: ../../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: |
| /// |
| /// ``` |
| /// // 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); |
| /// ``` |
| /// |
| /// [`from_utf8()`]: #method.from_utf8 |
| /// |
| /// # UTF-8 |
| /// |
| /// `String`s are always valid UTF-8. This has a few implications, the first of |
| /// which is that if you need a non-UTF-8 string, consider [`OsString`]. It is |
| /// similar, but without the UTF-8 constraint. The second implication is that |
| /// you cannot index into a `String`: |
| /// |
| /// ```ignore |
| /// let s = "hello"; |
| /// |
| /// println!("The first letter of s is {}", s[0]); // ERROR!!! |
| /// ``` |
| /// |
| /// [`OsString`]: ../../std/ffi/struct.OsString.html |
| /// |
| /// Indexing is intended to be a constant-time operation, but UTF-8 encoding |
| /// does not allow us to do this. Furtheremore, it's not clear what sort of |
| /// thing the index should return: a byte, a codepoint, or a grapheme cluster. |
| /// The [`as_bytes()`] and [`chars()`] methods return iterators over the first |
| /// two, respectively. |
| /// |
| /// [`as_bytes()`]: #method.as_bytes |
| /// [`chars()`]: #method.chars |
| /// |
| /// # Deref |
| /// |
| /// `String`s implement [`Deref`]`<Target=str>`, and so inherit all of [`str`]'s |
| /// methods. In addition, this means that you can pass a `String` to any |
| /// function which takes a [`&str`] by using an ampersand (`&`): |
| /// |
| /// ``` |
| /// fn takes_str(s: &str) { } |
| /// |
| /// let s = String::from("Hello"); |
| /// |
| /// takes_str(&s); |
| /// ``` |
| /// |
| /// [`&str`]: ../../std/primitive.str.html |
| /// [`Deref`]: ../../std/ops/trait.Deref.html |
| /// |
| /// 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. |
| /// |
| /// |
| /// # 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 std::mem; |
| /// |
| /// let story = String::from("Once upon a time..."); |
| /// |
| /// let ptr = story.as_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(ptr as *mut _, len, capacity) } ; |
| /// |
| /// assert_eq!(String::from("Once upon a time..."), s); |
| /// ``` |
| /// |
| /// [`as_ptr()`]: #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: |
| /// |
| /// ``` |
| /// let mut s = String::new(); |
| /// |
| /// 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()`] method to allocate the correct capacity initially: |
| /// |
| /// ``` |
| /// let mut s = String::with_capacity(25); |
| /// |
| /// println!("{}", s.capacity()); |
| /// |
| /// for _ in 0..5 { |
| /// s.push_str("hello"); |
| /// println!("{}", s.capacity()); |
| /// } |
| /// ``` |
| /// |
| /// [`with_capacity()`]: #method.with_capacity |
| /// |
| /// 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. |
| #[derive(PartialOrd, Eq, Ord)] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub struct String { |
| vec: Vec<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`]: ../../std/str/struct.Utf8Error.html |
| /// [`std::str`]: ../../std/str/index.html |
| /// [`u8`]: ../../std/primitive.u8.html |
| /// [`&str`]: ../../std/primitive.str.html |
| /// [`utf8_error()`]: #method.utf8_error |
| /// |
| /// # Examples |
| /// |
| /// Basic usage: |
| /// |
| /// ``` |
| /// // some invalid bytes, in a vector |
| /// let bytes = vec![0, 159]; |
| /// |
| /// let value = String::from_utf8(bytes); |
| /// |
| /// assert!(value.is_err()); |
| /// assert_eq!(vec![0, 159], value.unwrap_err().into_bytes()); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[derive(Debug)] |
| pub struct FromUtf8Error { |
| bytes: Vec<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()`] 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]; |
| /// |
| /// assert!(String::from_utf16(v).is_err()); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| #[derive(Debug)] |
| pub struct FromUtf16Error(()); |
| |
| 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, but 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] |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub 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 i 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 slice ([`&str`]) 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. |
| /// |
| /// [`&str`]: ../../std/primitive.str.html |
| /// [`u8`]: ../../std/primitive.u8.html |
| /// [`Vec<u8>`]: ../../std/vec/struct.Vec.html |
| /// |
| /// 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. |
| /// |
| /// [`from_utf8_unchecked()`]: struct.String.html#method.from_utf8_unchecked |
| /// |
| /// 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()`]. |
| /// |
| /// [`str::from_utf8()`]: ../../std/str/fn.from_utf8.html |
| /// |
| /// # 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. |
| /// |
| /// [`FromUtf8Error`]: struct.FromUtf8Error.html |
| #[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: 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`, which looks like this: � |
| /// |
| /// [`u8`]: ../../std/primitive.u8.html |
| /// [byteslice]: ../../std/primitive.slice.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 �World", output); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| pub fn from_utf8_lossy<'a>(v: &'a [u8]) -> Cow<'a, str> { |
| let mut i; |
| match str::from_utf8(v) { |
| Ok(s) => return Cow::Borrowed(s), |
| Err(e) => i = e.valid_up_to(), |
| } |
| |
| const TAG_CONT_U8: u8 = 128; |
| const REPLACEMENT: &'static [u8] = b"\xEF\xBF\xBD"; // U+FFFD in UTF-8 |
| let total = v.len(); |
| fn unsafe_get(xs: &[u8], i: usize) -> u8 { |
| unsafe { *xs.get_unchecked(i) } |
| } |
| fn safe_get(xs: &[u8], i: usize, total: usize) -> u8 { |
| if i >= total { |
| 0 |
| } else { |
| unsafe_get(xs, i) |
| } |
| } |
| |
| let mut res = String::with_capacity(total); |
| |
| if i > 0 { |
| unsafe { res.as_mut_vec().extend_from_slice(&v[..i]) }; |
| } |
| |
| // subseqidx is the index of the first byte of the subsequence we're |
| // looking at. It's used to copy a bunch of contiguous good codepoints |
| // at once instead of copying them one by one. |
| let mut subseqidx = i; |
| |
| while i < total { |
| let i_ = i; |
| let byte = unsafe_get(v, i); |
| i += 1; |
| |
| macro_rules! error { () => ({ |
| unsafe { |
| if subseqidx != i_ { |
| res.as_mut_vec().extend_from_slice(&v[subseqidx..i_]); |
| } |
| subseqidx = i; |
| res.as_mut_vec().extend_from_slice(REPLACEMENT); |
| } |
| })} |
| |
| if byte < 128 { |
| // subseqidx handles this |
| } else { |
| let w = unicode_str::utf8_char_width(byte); |
| |
| match w { |
| 2 => { |
| if safe_get(v, i, total) & 192 != TAG_CONT_U8 { |
| error!(); |
| continue; |
| } |
| i += 1; |
| } |
| 3 => { |
| match (byte, safe_get(v, i, total)) { |
| (0xE0, 0xA0...0xBF) => (), |
| (0xE1...0xEC, 0x80...0xBF) => (), |
| (0xED, 0x80...0x9F) => (), |
| (0xEE...0xEF, 0x80...0xBF) => (), |
| _ => { |
| error!(); |
| continue; |
| } |
| } |
| i += 1; |
| if safe_get(v, i, total) & 192 != TAG_CONT_U8 { |
| error!(); |
| continue; |
| } |
| i += 1; |
| } |
| 4 => { |
| match (byte, safe_get(v, i, total)) { |
| (0xF0, 0x90...0xBF) => (), |
| (0xF1...0xF3, 0x80...0xBF) => (), |
| (0xF4, 0x80...0x8F) => (), |
| _ => { |
| error!(); |
| continue; |
| } |
| } |
| i += 1; |
| if safe_get(v, i, total) & 192 != TAG_CONT_U8 { |
| error!(); |
| continue; |
| } |
| i += 1; |
| if safe_get(v, i, total) & 192 != TAG_CONT_U8 { |
| error!(); |
| continue; |
| } |
| i += 1; |
| } |
| _ => { |
| error!(); |
| continue; |
| } |
| } |
| } |
| } |
| if subseqidx < total { |
| unsafe { res.as_mut_vec().extend_from_slice(&v[subseqidx..total]) }; |
| } |
| Cow::Owned(res) |
| } |
| |
| /// Decode a UTF-16 encoded vector `v` into a `String`, returning `Err` |
| /// if `v` contains any invalid data. |
| /// |
| /// # 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> { |
| decode_utf16(v.iter().cloned()).collect::<Result<_, _>>().map_err(|_| FromUtf16Error(())) |
| } |
| |
| /// Decode a UTF-16 encoded vector `v` into a string, replacing |
| /// invalid data with the replacement character (U+FFFD). |
| /// |
| /// # 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() |
| } |
| |
| /// 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 datastructures. |
| /// |
| /// 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"); |
| /// let ptr = s.as_ptr(); |
| /// let len = s.len(); |
| /// let capacity = s.capacity(); |
| /// |
| /// mem::forget(s); |
| /// |
| /// let s = String::from_raw_parts(ptr as *mut _, 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. |
| #[inline] |
| #[stable(feature = "string_as_str", since = "1.7.0")] |
| pub fn as_str(&self) -> &str { |
| self |
| } |
| |
| /// Extracts a string slice containing the entire string. |
| #[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. |
| /// |
| /// [`reserve_exact()`]: #method.reserve_exact |
| /// |
| /// # Panics |
| /// |
| /// Panics if the new capacity overflows `usize`. |
| /// |
| /// # 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) |
| } |
| |
| /// 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() |
| } |
| |
| /// Appends the given `char` to the end of this `String`. |
| /// |
| /// # 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().as_slice()), |
| } |
| } |
| |
| /// Returns a byte slice of this `String`'s contents. |
| /// |
| /// # 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. |
| /// |
| /// # 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. |
| /// |
| /// # 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 = match self.chars().rev().next() { |
| Some(ch) => ch, |
| None => return None, |
| }; |
| 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().offset(next as isize), |
| self.vec.as_mut_ptr().offset(idx as isize), |
| len - next); |
| self.vec.set_len(len - (next - idx)); |
| } |
| ch |
| } |
| |
| /// 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) { |
| let len = self.len(); |
| assert!(idx <= len); |
| assert!(self.is_char_boundary(idx)); |
| let bits = ch.encode_utf8(); |
| |
| unsafe { |
| self.insert_bytes(idx, bits.as_slice()); |
| } |
| } |
| |
| 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().offset(idx as isize), |
| self.vec.as_mut_ptr().offset((idx + amt) as isize), |
| len - idx); |
| ptr::copy(bytes.as_ptr(), |
| self.vec.as_mut_ptr().offset(idx as isize), |
| amt); |
| self.vec.set_len(len + amt); |
| } |
| |
| /// Inserts a string 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: |
| /// |
| /// ``` |
| /// #![feature(insert_str)] |
| /// |
| /// let mut s = String::from("bar"); |
| /// |
| /// s.insert_str(0, "foo"); |
| /// |
| /// assert_eq!("foobar", s); |
| /// ``` |
| #[inline] |
| #[unstable(feature = "insert_str", |
| reason = "recent addition", |
| issue = "0")] |
| pub fn insert_str(&mut self, idx: usize, string: &str) { |
| let len = self.len(); |
| assert!(idx <= len); |
| 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. |
| /// |
| /// # Examples |
| /// |
| /// Basic usage: |
| /// |
| /// ``` |
| /// let a = String::from("foo"); |
| /// |
| /// assert_eq!(a.len(), 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. |
| /// |
| /// Returns `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 |
| } |
| |
| /// 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() |
| } |
| |
| /// Create 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: RangeArgument<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 = *range.start().unwrap_or(&0); |
| let end = *range.end().unwrap_or(&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: start, |
| end: end, |
| iter: chars_iter, |
| string: self_ptr, |
| } |
| } |
| |
| /// Converts this `String` into a `Box<str>`. |
| /// |
| /// This will drop any excess capacity. |
| /// |
| /// # Examples |
| /// |
| /// Basic usage: |
| /// |
| /// ``` |
| /// let s = String::from("hello"); |
| /// |
| /// let b = s.into_boxed_str(); |
| /// ``` |
| #[stable(feature = "box_str", since = "1.4.0")] |
| pub fn into_boxed_str(self) -> Box<str> { |
| let slice = self.vec.into_boxed_slice(); |
| unsafe { mem::transmute::<Box<[u8]>, Box<str>>(slice) } |
| } |
| } |
| |
| impl FromUtf8Error { |
| /// 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 = "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 buf = String::new(); |
| buf.extend(iter); |
| 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); |
| for ch in iterator { |
| self.push(ch) |
| } |
| } |
| } |
| |
| #[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) { |
| for s in iter { |
| 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) { |
| for s in iter { |
| 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, $rhs: ty) => { |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'a, 'b> PartialEq<$rhs> for $lhs { |
| #[inline] |
| fn eq(&self, other: &$rhs) -> bool { PartialEq::eq(&self[..], &other[..]) } |
| #[inline] |
| fn ne(&self, other: &$rhs) -> bool { PartialEq::ne(&self[..], &other[..]) } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'a, 'b> PartialEq<$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 { |
| #[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) |
| } |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<'a> Add<&'a str> for String { |
| type Output = String; |
| |
| #[inline] |
| fn add(mut self, other: &str) -> String { |
| self.push_str(other); |
| self |
| } |
| } |
| |
| #[stable(feature = "stringaddassign", since = "1.12.0")] |
| impl<'a> AddAssign<&'a 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) } |
| } |
| } |
| #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")] |
| impl ops::Index<ops::RangeInclusive<usize>> for String { |
| type Output = str; |
| |
| #[inline] |
| fn index(&self, index: ops::RangeInclusive<usize>) -> &str { |
| Index::index(&**self, index) |
| } |
| } |
| #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")] |
| 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 = "1.2.0")] |
| 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 = "1.2.0")] |
| 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 = "1.2.0")] |
| 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 = "1.2.0")] |
| impl ops::IndexMut<ops::RangeFull> for String { |
| #[inline] |
| fn index_mut(&mut self, _index: ops::RangeFull) -> &mut str { |
| unsafe { mem::transmute(&mut *self.vec) } |
| } |
| } |
| #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")] |
| 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) |
| } |
| } |
| #[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")] |
| 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 = "1.2.0")] |
| impl ops::DerefMut for String { |
| #[inline] |
| fn deref_mut(&mut self) -> &mut str { |
| unsafe { mem::transmute(&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")] |
| #[derive(Copy)] |
| pub enum ParseError {} |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl FromStr for String { |
| type Err = ParseError; |
| #[inline] |
| fn from_str(s: &str) -> Result<String, ParseError> { |
| Ok(String::from(s)) |
| } |
| } |
| |
| #[stable(feature = "str_parse_error", since = "1.5.0")] |
| impl Clone for ParseError { |
| fn clone(&self) -> ParseError { |
| match *self {} |
| } |
| } |
| |
| #[stable(feature = "str_parse_error", since = "1.5.0")] |
| impl fmt::Debug for ParseError { |
| fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result { |
| match *self {} |
| } |
| } |
| |
| #[stable(feature = "str_parse_error2", since = "1.8.0")] |
| impl fmt::Display for ParseError { |
| fn fmt(&self, _: &mut fmt::Formatter) -> fmt::Result { |
| match *self {} |
| } |
| } |
| |
| #[stable(feature = "str_parse_error", since = "1.5.0")] |
| impl PartialEq for ParseError { |
| fn eq(&self, _: &ParseError) -> bool { |
| match *self {} |
| } |
| } |
| |
| #[stable(feature = "str_parse_error", since = "1.5.0")] |
| impl Eq for ParseError {} |
| |
| /// 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()); |
| /// ``` |
| #[stable(feature = "rust1", since = "1.0.0")] |
| fn to_string(&self) -> String; |
| } |
| |
| #[stable(feature = "rust1", since = "1.0.0")] |
| impl<T: fmt::Display + ?Sized> ToString for T { |
| #[inline] |
| default fn to_string(&self) -> String { |
| use core::fmt::Write; |
| let mut buf = String::new(); |
| let _ = buf.write_fmt(format_args!("{}", self)); |
| 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 = "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<'a> From<&'a str> for String { |
| fn from(s: &'a str) -> String { |
| s.to_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 = "rust1", since = "1.0.0")] |
| impl Into<Vec<u8>> for String { |
| fn into(self) -> Vec<u8> { |
| self.into_bytes() |
| } |
| } |
| |
| #[stable(feature = "stringfromchars", since = "1.12.0")] |
| impl<'a> From<&'a [char]> for String { |
| #[inline] |
| fn from(v: &'a [char]) -> String { |
| let mut s = String::with_capacity(v.len()); |
| for c in v { |
| s.push(*c); |
| } |
| s |
| } |
| } |
| |
| #[stable(feature = "stringfromchars", since = "1.12.0")] |
| impl From<Vec<char>> for String { |
| #[inline] |
| fn from(v: Vec<char>) -> String { |
| String::from(v.as_slice()) |
| } |
| } |
| |
| #[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 = "drain", since = "1.6.0")] |
| unsafe impl<'a> Sync for Drain<'a> {} |
| #[stable(feature = "drain", since = "1.6.0")] |
| unsafe impl<'a> Send for Drain<'a> {} |
| |
| #[stable(feature = "drain", since = "1.6.0")] |
| impl<'a> Drop for Drain<'a> { |
| 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<'a> Iterator for Drain<'a> { |
| type Item = char; |
| |
| #[inline] |
| fn next(&mut self) -> Option<char> { |
| self.iter.next() |
| } |
| |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| self.iter.size_hint() |
| } |
| } |
| |
| #[stable(feature = "drain", since = "1.6.0")] |
| impl<'a> DoubleEndedIterator for Drain<'a> { |
| #[inline] |
| fn next_back(&mut self) -> Option<char> { |
| self.iter.next_back() |
| } |
| } |