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fuchsia / third_party / rust / 15f159addefd8fea7564ba7617c8af78582b7816 / . / src / libcore / str / mod.rs
blob: 25b7eec5b33432ab5cb5689e0cf48d202d4e8999 [file] [log] [blame]
// ignore-tidy-filelength
// ignore-tidy-undocumented-unsafe
//! String manipulation.
//!
//! For more details, see the `std::str` module.
#![stable(feature = "rust1", since = "1.0.0")]
use self::pattern::Pattern;
use self::pattern::{Searcher, ReverseSearcher, DoubleEndedSearcher};
use crate::char;
use crate::fmt::{self, Write};
use crate::iter::{Map, Cloned, FusedIterator, TrustedLen, TrustedRandomAccess, Filter};
use crate::iter::{Flatten, FlatMap, Chain};
use crate::slice::{self, SliceIndex, Split as SliceSplit};
use crate::mem;
use crate::ops::Try;
use crate::option;
pub mod pattern;
#[unstable(feature = "str_internals", issue = "0")]
#[allow(missing_docs)]
pub mod lossy;
/// Parse a value from a string
///
/// `FromStr`'s [`from_str`] method is often used implicitly, through
/// [`str`]'s [`parse`] method. See [`parse`]'s documentation for examples.
///
/// [`from_str`]: #tymethod.from_str
/// [`str`]: ../../std/primitive.str.html
/// [`parse`]: ../../std/primitive.str.html#method.parse
///
/// `FromStr` does not have a lifetime parameter, and so you can only parse types
/// that do not contain a lifetime parameter themselves. In other words, you can
/// parse an `i32` with `FromStr`, but not a `&i32`. You can parse a struct that
/// contains an `i32`, but not one that contains an `&i32`.
///
/// # Examples
///
/// Basic implementation of `FromStr` on an example `Point` type:
///
/// ```
/// use std::str::FromStr;
/// use std::num::ParseIntError;
///
/// #[derive(Debug, PartialEq)]
/// struct Point {
/// x: i32,
/// y: i32
/// }
///
/// impl FromStr for Point {
/// type Err = ParseIntError;
///
/// fn from_str(s: &str) -> Result<Self, Self::Err> {
/// let coords: Vec<&str> = s.trim_matches(|p| p == '(' || p == ')' )
/// .split(',')
/// .collect();
///
/// let x_fromstr = coords[0].parse::<i32>()?;
/// let y_fromstr = coords[1].parse::<i32>()?;
///
/// Ok(Point { x: x_fromstr, y: y_fromstr })
/// }
/// }
///
/// let p = Point::from_str("(1,2)");
/// assert_eq!(p.unwrap(), Point{ x: 1, y: 2} )
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub trait FromStr: Sized {
/// The associated error which can be returned from parsing.
#[stable(feature = "rust1", since = "1.0.0")]
type Err;
/// Parses a string `s` to return a value of this type.
///
/// If parsing succeeds, return the value inside [`Ok`], otherwise
/// when the string is ill-formatted return an error specific to the
/// inside [`Err`]. The error type is specific to implementation of the trait.
///
/// [`Ok`]: ../../std/result/enum.Result.html#variant.Ok
/// [`Err`]: ../../std/result/enum.Result.html#variant.Err
///
/// # Examples
///
/// Basic usage with [`i32`][ithirtytwo], a type that implements `FromStr`:
///
/// [ithirtytwo]: ../../std/primitive.i32.html
///
/// ```
/// use std::str::FromStr;
///
/// let s = "5";
/// let x = i32::from_str(s).unwrap();
///
/// assert_eq!(5, x);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
fn from_str(s: &str) -> Result<Self, Self::Err>;
}
#[stable(feature = "rust1", since = "1.0.0")]
impl FromStr for bool {
type Err = ParseBoolError;
/// Parse a `bool` from a string.
///
/// Yields a `Result<bool, ParseBoolError>`, because `s` may or may not
/// actually be parseable.
///
/// # Examples
///
/// ```
/// use std::str::FromStr;
///
/// assert_eq!(FromStr::from_str("true"), Ok(true));
/// assert_eq!(FromStr::from_str("false"), Ok(false));
/// assert!(<bool as FromStr>::from_str("not even a boolean").is_err());
/// ```
///
/// Note, in many cases, the `.parse()` method on `str` is more proper.
///
/// ```
/// assert_eq!("true".parse(), Ok(true));
/// assert_eq!("false".parse(), Ok(false));
/// assert!("not even a boolean".parse::<bool>().is_err());
/// ```
#[inline]
fn from_str(s: &str) -> Result<bool, ParseBoolError> {
match s {
"true" => Ok(true),
"false" => Ok(false),
_ => Err(ParseBoolError { _priv: () }),
}
}
}
/// An error returned when parsing a `bool` using [`from_str`] fails
///
/// [`from_str`]: ../../std/primitive.bool.html#method.from_str
#[derive(Debug, Clone, PartialEq, Eq)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct ParseBoolError { _priv: () }
#[stable(feature = "rust1", since = "1.0.0")]
impl fmt::Display for ParseBoolError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
"provided string was not `true` or `false`".fmt(f)
}
}
/*
Section: Creating a string
*/
/// Errors which can occur when attempting to interpret a sequence of [`u8`]
/// as a string.
///
/// [`u8`]: ../../std/primitive.u8.html
///
/// As such, the `from_utf8` family of functions and methods for both [`String`]s
/// and [`&str`]s make use of this error, for example.
///
/// [`String`]: ../../std/string/struct.String.html#method.from_utf8
/// [`&str`]: ../../std/str/fn.from_utf8.html
///
/// # Examples
///
/// This error type’s methods can be used to create functionality
/// similar to `String::from_utf8_lossy` without allocating heap memory:
///
/// ```
/// fn from_utf8_lossy<F>(mut input: &[u8], mut push: F) where F: FnMut(&str) {
/// loop {
/// match std::str::from_utf8(input) {
/// Ok(valid) => {
/// push(valid);
/// break
/// }
/// Err(error) => {
/// let (valid, after_valid) = input.split_at(error.valid_up_to());
/// unsafe {
/// push(std::str::from_utf8_unchecked(valid))
/// }
/// push("\u{FFFD}");
///
/// if let Some(invalid_sequence_length) = error.error_len() {
/// input = &after_valid[invalid_sequence_length..]
/// } else {
/// break
/// }
/// }
/// }
/// }
/// }
/// ```
#[derive(Copy, Eq, PartialEq, Clone, Debug)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Utf8Error {
valid_up_to: usize,
error_len: Option<u8>,
}
impl Utf8Error {
/// Returns the index in the given string up to which valid UTF-8 was
/// verified.
///
/// It is the maximum index such that `from_utf8(&input[..index])`
/// would return `Ok(_)`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::str;
///
/// // some invalid bytes, in a vector
/// let sparkle_heart = vec![0, 159, 146, 150];
///
/// // std::str::from_utf8 returns a Utf8Error
/// let error = str::from_utf8(&sparkle_heart).unwrap_err();
///
/// // the second byte is invalid here
/// assert_eq!(1, error.valid_up_to());
/// ```
#[stable(feature = "utf8_error", since = "1.5.0")]
pub fn valid_up_to(&self) -> usize { self.valid_up_to }
/// Provides more information about the failure:
///
/// * `None`: the end of the input was reached unexpectedly.
/// `self.valid_up_to()` is 1 to 3 bytes from the end of the input.
/// If a byte stream (such as a file or a network socket) is being decoded incrementally,
/// this could be a valid `char` whose UTF-8 byte sequence is spanning multiple chunks.
///
/// * `Some(len)`: an unexpected byte was encountered.
/// The length provided is that of the invalid byte sequence
/// that starts at the index given by `valid_up_to()`.
/// Decoding should resume after that sequence
/// (after inserting a [`U+FFFD REPLACEMENT CHARACTER`][U+FFFD]) in case of
/// lossy decoding.
///
/// [U+FFFD]: ../../std/char/constant.REPLACEMENT_CHARACTER.html
#[stable(feature = "utf8_error_error_len", since = "1.20.0")]
pub fn error_len(&self) -> Option<usize> {
self.error_len.map(|len| len as usize)
}
}
/// Converts a slice of bytes to a string slice.
///
/// A string slice ([`&str`]) is made of bytes ([`u8`]), and a byte slice
/// ([`&[u8]`][byteslice]) is made of bytes, so this function converts between
/// the two. Not all byte slices are valid string slices, however: [`&str`] 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
/// [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 validity check, there is an unsafe version of
/// this function, [`from_utf8_unchecked`][fromutf8u], which has the same
/// behavior but skips the check.
///
/// [fromutf8u]: fn.from_utf8_unchecked.html
///
/// If you need a `String` instead of a `&str`, consider
/// [`String::from_utf8`][string].
///
/// [string]: ../../std/string/struct.String.html#method.from_utf8
///
/// Because you can stack-allocate a `[u8; N]`, and you can take a
/// [`&[u8]`][byteslice] of it, this function is one way to have a
/// stack-allocated string. There is an example of this in the
/// examples section below.
///
/// [byteslice]: ../../std/primitive.slice.html
///
/// # Errors
///
/// Returns `Err` if the slice is not UTF-8 with a description as to why the
/// provided slice is not UTF-8.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::str;
///
/// // some bytes, in a vector
/// let sparkle_heart = vec![240, 159, 146, 150];
///
/// // We know these bytes are valid, so just use `unwrap()`.
/// let sparkle_heart = str::from_utf8(&sparkle_heart).unwrap();
///
/// assert_eq!("💖", sparkle_heart);
/// ```
///
/// Incorrect bytes:
///
/// ```
/// use std::str;
///
/// // some invalid bytes, in a vector
/// let sparkle_heart = vec![0, 159, 146, 150];
///
/// assert!(str::from_utf8(&sparkle_heart).is_err());
/// ```
///
/// See the docs for [`Utf8Error`][error] for more details on the kinds of
/// errors that can be returned.
///
/// [error]: struct.Utf8Error.html
///
/// A "stack allocated string":
///
/// ```
/// use std::str;
///
/// // some bytes, in a stack-allocated array
/// let sparkle_heart = [240, 159, 146, 150];
///
/// // We know these bytes are valid, so just use `unwrap()`.
/// let sparkle_heart = str::from_utf8(&sparkle_heart).unwrap();
///
/// assert_eq!("💖", sparkle_heart);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn from_utf8(v: &[u8]) -> Result<&str, Utf8Error> {
run_utf8_validation(v)?;
Ok(unsafe { from_utf8_unchecked(v) })
}
/// Converts a mutable slice of bytes to a mutable string slice.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::str;
///
/// // "Hello, Rust!" as a mutable vector
/// let mut hellorust = vec![72, 101, 108, 108, 111, 44, 32, 82, 117, 115, 116, 33];
///
/// // As we know these bytes are valid, we can use `unwrap()`
/// let outstr = str::from_utf8_mut(&mut hellorust).unwrap();
///
/// assert_eq!("Hello, Rust!", outstr);
/// ```
///
/// Incorrect bytes:
///
/// ```
/// use std::str;
///
/// // Some invalid bytes in a mutable vector
/// let mut invalid = vec![128, 223];
///
/// assert!(str::from_utf8_mut(&mut invalid).is_err());
/// ```
/// See the docs for [`Utf8Error`][error] for more details on the kinds of
/// errors that can be returned.
///
/// [error]: struct.Utf8Error.html
#[stable(feature = "str_mut_extras", since = "1.20.0")]
pub fn from_utf8_mut(v: &mut [u8]) -> Result<&mut str, Utf8Error> {
run_utf8_validation(v)?;
Ok(unsafe { from_utf8_unchecked_mut(v) })
}
/// Converts a slice of bytes to a string slice without checking
/// that the string contains valid UTF-8.
///
/// See the safe version, [`from_utf8`][fromutf8], for more information.
///
/// [fromutf8]: fn.from_utf8.html
///
/// # 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, undefined behavior
/// results, as the rest of Rust assumes that [`&str`]s are valid UTF-8.
///
/// [`&str`]: ../../std/primitive.str.html
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::str;
///
/// // some bytes, in a vector
/// let sparkle_heart = vec![240, 159, 146, 150];
///
/// let sparkle_heart = unsafe {
/// str::from_utf8_unchecked(&sparkle_heart)
/// };
///
/// assert_eq!("💖", sparkle_heart);
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub unsafe fn from_utf8_unchecked(v: &[u8]) -> &str {
&*(v as *const [u8] as *const str)
}
/// Converts a slice of bytes to a string slice without checking
/// that the string contains valid UTF-8; mutable version.
///
/// See the immutable version, [`from_utf8_unchecked()`][fromutf8], for more information.
///
/// [fromutf8]: fn.from_utf8_unchecked.html
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// use std::str;
///
/// let mut heart = vec![240, 159, 146, 150];
/// let heart = unsafe { str::from_utf8_unchecked_mut(&mut heart) };
///
/// assert_eq!("💖", heart);
/// ```
#[inline]
#[stable(feature = "str_mut_extras", since = "1.20.0")]
pub unsafe fn from_utf8_unchecked_mut(v: &mut [u8]) -> &mut str {
&mut *(v as *mut [u8] as *mut str)
}
#[stable(feature = "rust1", since = "1.0.0")]
impl fmt::Display for Utf8Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if let Some(error_len) = self.error_len {
write!(f, "invalid utf-8 sequence of {} bytes from index {}",
error_len, self.valid_up_to)
} else {
write!(f, "incomplete utf-8 byte sequence from index {}", self.valid_up_to)
}
}
}
/*
Section: Iterators
*/
/// An iterator over the [`char`]s of a string slice.
///
/// [`char`]: ../../std/primitive.char.html
///
/// This struct is created by the [`chars`] method on [`str`].
/// See its documentation for more.
///
/// [`chars`]: ../../std/primitive.str.html#method.chars
/// [`str`]: ../../std/primitive.str.html
#[derive(Clone)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Chars<'a> {
iter: slice::Iter<'a, u8>
}
/// Returns the initial codepoint accumulator for the first byte.
/// The first byte is special, only want bottom 5 bits for width 2, 4 bits
/// for width 3, and 3 bits for width 4.
#[inline]
fn utf8_first_byte(byte: u8, width: u32) -> u32 { (byte & (0x7F >> width)) as u32 }
/// Returns the value of `ch` updated with continuation byte `byte`.
#[inline]
fn utf8_acc_cont_byte(ch: u32, byte: u8) -> u32 { (ch << 6) | (byte & CONT_MASK) as u32 }
/// Checks whether the byte is a UTF-8 continuation byte (i.e., starts with the
/// bits `10`).
#[inline]
fn utf8_is_cont_byte(byte: u8) -> bool { (byte & !CONT_MASK) == TAG_CONT_U8 }
#[inline]
fn unwrap_or_0(opt: Option<&u8>) -> u8 {
match opt {
Some(&byte) => byte,
None => 0,
}
}
/// Reads the next code point out of a byte iterator (assuming a
/// UTF-8-like encoding).
#[unstable(feature = "str_internals", issue = "0")]
#[inline]
pub fn next_code_point<'a, I: Iterator<Item = &'a u8>>(bytes: &mut I) -> Option<u32> {
// Decode UTF-8
let x = *bytes.next()?;
if x < 128 {
return Some(x as u32)
}
// Multibyte case follows
// Decode from a byte combination out of: [[[x y] z] w]
// NOTE: Performance is sensitive to the exact formulation here
let init = utf8_first_byte(x, 2);
let y = unwrap_or_0(bytes.next());
let mut ch = utf8_acc_cont_byte(init, y);
if x >= 0xE0 {
// [[x y z] w] case
// 5th bit in 0xE0 .. 0xEF is always clear, so `init` is still valid
let z = unwrap_or_0(bytes.next());
let y_z = utf8_acc_cont_byte((y & CONT_MASK) as u32, z);
ch = init << 12 | y_z;
if x >= 0xF0 {
// [x y z w] case
// use only the lower 3 bits of `init`
let w = unwrap_or_0(bytes.next());
ch = (init & 7) << 18 | utf8_acc_cont_byte(y_z, w);
}
}
Some(ch)
}
/// Reads the last code point out of a byte iterator (assuming a
/// UTF-8-like encoding).
#[inline]
fn next_code_point_reverse<'a, I>(bytes: &mut I) -> Option<u32>
where I: DoubleEndedIterator<Item = &'a u8>,
{
// Decode UTF-8
let w = match *bytes.next_back()? {
next_byte if next_byte < 128 => return Some(next_byte as u32),
back_byte => back_byte,
};
// Multibyte case follows
// Decode from a byte combination out of: [x [y [z w]]]
let mut ch;
let z = unwrap_or_0(bytes.next_back());
ch = utf8_first_byte(z, 2);
if utf8_is_cont_byte(z) {
let y = unwrap_or_0(bytes.next_back());
ch = utf8_first_byte(y, 3);
if utf8_is_cont_byte(y) {
let x = unwrap_or_0(bytes.next_back());
ch = utf8_first_byte(x, 4);
ch = utf8_acc_cont_byte(ch, y);
}
ch = utf8_acc_cont_byte(ch, z);
}
ch = utf8_acc_cont_byte(ch, w);
Some(ch)
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> Iterator for Chars<'a> {
type Item = char;
#[inline]
fn next(&mut self) -> Option<char> {
next_code_point(&mut self.iter).map(|ch| {
// str invariant says `ch` is a valid Unicode Scalar Value
unsafe {
char::from_u32_unchecked(ch)
}
})
}
#[inline]
fn count(self) -> usize {
// length in `char` is equal to the number of non-continuation bytes
let bytes_len = self.iter.len();
let mut cont_bytes = 0;
for &byte in self.iter {
cont_bytes += utf8_is_cont_byte(byte) as usize;
}
bytes_len - cont_bytes
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let len = self.iter.len();
// `(len + 3)` can't overflow, because we know that the `slice::Iter`
// belongs to a slice in memory which has a maximum length of
// `isize::MAX` (that's well below `usize::MAX`).
((len + 3) / 4, Some(len))
}
#[inline]
fn last(mut self) -> Option<char> {
// No need to go through the entire string.
self.next_back()
}
}
#[stable(feature = "chars_debug_impl", since = "1.38.0")]
impl fmt::Debug for Chars<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "Chars(")?;
f.debug_list().entries(self.clone()).finish()?;
write!(f, ")")?;
Ok(())
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> DoubleEndedIterator for Chars<'a> {
#[inline]
fn next_back(&mut self) -> Option<char> {
next_code_point_reverse(&mut self.iter).map(|ch| {
// str invariant says `ch` is a valid Unicode Scalar Value
unsafe {
char::from_u32_unchecked(ch)
}
})
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl FusedIterator for Chars<'_> {}
impl<'a> Chars<'a> {
/// Views the underlying data as a subslice of the original data.
///
/// This has the same lifetime as the original slice, and so the
/// iterator can continue to be used while this exists.
///
/// # Examples
///
/// ```
/// let mut chars = "abc".chars();
///
/// assert_eq!(chars.as_str(), "abc");
/// chars.next();
/// assert_eq!(chars.as_str(), "bc");
/// chars.next();
/// chars.next();
/// assert_eq!(chars.as_str(), "");
/// ```
#[stable(feature = "iter_to_slice", since = "1.4.0")]
#[inline]
pub fn as_str(&self) -> &'a str {
unsafe { from_utf8_unchecked(self.iter.as_slice()) }
}
}
/// An iterator over the [`char`]s of a string slice, and their positions.
///
/// [`char`]: ../../std/primitive.char.html
///
/// This struct is created by the [`char_indices`] method on [`str`].
/// See its documentation for more.
///
/// [`char_indices`]: ../../std/primitive.str.html#method.char_indices
/// [`str`]: ../../std/primitive.str.html
#[derive(Clone, Debug)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct CharIndices<'a> {
front_offset: usize,
iter: Chars<'a>,
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> Iterator for CharIndices<'a> {
type Item = (usize, char);
#[inline]
fn next(&mut self) -> Option<(usize, char)> {
let pre_len = self.iter.iter.len();
match self.iter.next() {
None => None,
Some(ch) => {
let index = self.front_offset;
let len = self.iter.iter.len();
self.front_offset += pre_len - len;
Some((index, ch))
}
}
}
#[inline]
fn count(self) -> usize {
self.iter.count()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
#[inline]
fn last(mut self) -> Option<(usize, char)> {
// No need to go through the entire string.
self.next_back()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> DoubleEndedIterator for CharIndices<'a> {
#[inline]
fn next_back(&mut self) -> Option<(usize, char)> {
self.iter.next_back().map(|ch| {
let index = self.front_offset + self.iter.iter.len();
(index, ch)
})
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl FusedIterator for CharIndices<'_> {}
impl<'a> CharIndices<'a> {
/// Views the underlying data as a subslice of the original data.
///
/// This has the same lifetime as the original slice, and so the
/// iterator can continue to be used while this exists.
#[stable(feature = "iter_to_slice", since = "1.4.0")]
#[inline]
pub fn as_str(&self) -> &'a str {
self.iter.as_str()
}
}
/// An iterator over the bytes of a string slice.
///
/// This struct is created by the [`bytes`] method on [`str`].
/// See its documentation for more.
///
/// [`bytes`]: ../../std/primitive.str.html#method.bytes
/// [`str`]: ../../std/primitive.str.html
#[stable(feature = "rust1", since = "1.0.0")]
#[derive(Clone, Debug)]
pub struct Bytes<'a>(Cloned<slice::Iter<'a, u8>>);
#[stable(feature = "rust1", since = "1.0.0")]
impl Iterator for Bytes<'_> {
type Item = u8;
#[inline]
fn next(&mut self) -> Option<u8> {
self.0.next()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.0.size_hint()
}
#[inline]
fn count(self) -> usize {
self.0.count()
}
#[inline]
fn last(self) -> Option<Self::Item> {
self.0.last()
}
#[inline]
fn nth(&mut self, n: usize) -> Option<Self::Item> {
self.0.nth(n)
}
#[inline]
fn all<F>(&mut self, f: F) -> bool where F: FnMut(Self::Item) -> bool {
self.0.all(f)
}
#[inline]
fn any<F>(&mut self, f: F) -> bool where F: FnMut(Self::Item) -> bool {
self.0.any(f)
}
#[inline]
fn find<P>(&mut self, predicate: P) -> Option<Self::Item> where
P: FnMut(&Self::Item) -> bool
{
self.0.find(predicate)
}
#[inline]
fn position<P>(&mut self, predicate: P) -> Option<usize> where
P: FnMut(Self::Item) -> bool
{
self.0.position(predicate)
}
#[inline]
fn rposition<P>(&mut self, predicate: P) -> Option<usize> where
P: FnMut(Self::Item) -> bool
{
self.0.rposition(predicate)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl DoubleEndedIterator for Bytes<'_> {
#[inline]
fn next_back(&mut self) -> Option<u8> {
self.0.next_back()
}
#[inline]
fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
self.0.nth_back(n)
}
#[inline]
fn rfind<P>(&mut self, predicate: P) -> Option<Self::Item> where
P: FnMut(&Self::Item) -> bool
{
self.0.rfind(predicate)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl ExactSizeIterator for Bytes<'_> {
#[inline]
fn len(&self) -> usize {
self.0.len()
}
#[inline]
fn is_empty(&self) -> bool {
self.0.is_empty()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl FusedIterator for Bytes<'_> {}
#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl TrustedLen for Bytes<'_> {}
#[doc(hidden)]
unsafe impl TrustedRandomAccess for Bytes<'_> {
unsafe fn get_unchecked(&mut self, i: usize) -> u8 {
self.0.get_unchecked(i)
}
fn may_have_side_effect() -> bool { false }
}
/// This macro generates a Clone impl for string pattern API
/// wrapper types of the form X<'a, P>
macro_rules! derive_pattern_clone {
(clone $t:ident with |$s:ident| $e:expr) => {
impl<'a, P> Clone for $t<'a, P>
where
P: Pattern<'a, Searcher: Clone>,
{
fn clone(&self) -> Self {
let $s = self;
$e
}
}
}
}
/// This macro generates two public iterator structs
/// wrapping a private internal one that makes use of the `Pattern` API.
///
/// For all patterns `P: Pattern<'a>` the following items will be
/// generated (generics omitted):
///
/// struct $forward_iterator($internal_iterator);
/// struct $reverse_iterator($internal_iterator);
///
/// impl Iterator for $forward_iterator
/// { /* internal ends up calling Searcher::next_match() */ }
///
/// impl DoubleEndedIterator for $forward_iterator
/// where P::Searcher: DoubleEndedSearcher
/// { /* internal ends up calling Searcher::next_match_back() */ }
///
/// impl Iterator for $reverse_iterator
/// where P::Searcher: ReverseSearcher
/// { /* internal ends up calling Searcher::next_match_back() */ }
///
/// impl DoubleEndedIterator for $reverse_iterator
/// where P::Searcher: DoubleEndedSearcher
/// { /* internal ends up calling Searcher::next_match() */ }
///
/// The internal one is defined outside the macro, and has almost the same
/// semantic as a DoubleEndedIterator by delegating to `pattern::Searcher` and
/// `pattern::ReverseSearcher` for both forward and reverse iteration.
///
/// "Almost", because a `Searcher` and a `ReverseSearcher` for a given
/// `Pattern` might not return the same elements, so actually implementing
/// `DoubleEndedIterator` for it would be incorrect.
/// (See the docs in `str::pattern` for more details)
///
/// However, the internal struct still represents a single ended iterator from
/// either end, and depending on pattern is also a valid double ended iterator,
/// so the two wrapper structs implement `Iterator`
/// and `DoubleEndedIterator` depending on the concrete pattern type, leading
/// to the complex impls seen above.
macro_rules! generate_pattern_iterators {
{
// Forward iterator
forward:
$(#[$forward_iterator_attribute:meta])*
struct $forward_iterator:ident;
// Reverse iterator
reverse:
$(#[$reverse_iterator_attribute:meta])*
struct $reverse_iterator:ident;
// Stability of all generated items
stability:
$(#[$common_stability_attribute:meta])*
// Internal almost-iterator that is being delegated to
internal:
$internal_iterator:ident yielding ($iterty:ty);
// Kind of delegation - either single ended or double ended
delegate $($t:tt)*
} => {
$(#[$forward_iterator_attribute])*
$(#[$common_stability_attribute])*
pub struct $forward_iterator<'a, P: Pattern<'a>>($internal_iterator<'a, P>);
$(#[$common_stability_attribute])*
impl<'a, P> fmt::Debug for $forward_iterator<'a, P>
where
P: Pattern<'a, Searcher: fmt::Debug>,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple(stringify!($forward_iterator))
.field(&self.0)
.finish()
}
}
$(#[$common_stability_attribute])*
impl<'a, P: Pattern<'a>> Iterator for $forward_iterator<'a, P> {
type Item = $iterty;
#[inline]
fn next(&mut self) -> Option<$iterty> {
self.0.next()
}
}
$(#[$common_stability_attribute])*
impl<'a, P> Clone for $forward_iterator<'a, P>
where
P: Pattern<'a, Searcher: Clone>,
{
fn clone(&self) -> Self {
$forward_iterator(self.0.clone())
}
}
$(#[$reverse_iterator_attribute])*
$(#[$common_stability_attribute])*
pub struct $reverse_iterator<'a, P: Pattern<'a>>($internal_iterator<'a, P>);
$(#[$common_stability_attribute])*
impl<'a, P> fmt::Debug for $reverse_iterator<'a, P>
where
P: Pattern<'a, Searcher: fmt::Debug>,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple(stringify!($reverse_iterator))
.field(&self.0)
.finish()
}
}
$(#[$common_stability_attribute])*
impl<'a, P> Iterator for $reverse_iterator<'a, P>
where
P: Pattern<'a, Searcher: ReverseSearcher<'a>>,
{
type Item = $iterty;
#[inline]
fn next(&mut self) -> Option<$iterty> {
self.0.next_back()
}
}
$(#[$common_stability_attribute])*
impl<'a, P> Clone for $reverse_iterator<'a, P>
where
P: Pattern<'a, Searcher: Clone>,
{
fn clone(&self) -> Self {
$reverse_iterator(self.0.clone())
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, P: Pattern<'a>> FusedIterator for $forward_iterator<'a, P> {}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, P> FusedIterator for $reverse_iterator<'a, P>
where
P: Pattern<'a, Searcher: ReverseSearcher<'a>>,
{}
generate_pattern_iterators!($($t)* with $(#[$common_stability_attribute])*,
$forward_iterator,
$reverse_iterator, $iterty);
};
{
double ended; with $(#[$common_stability_attribute:meta])*,
$forward_iterator:ident,
$reverse_iterator:ident, $iterty:ty
} => {
$(#[$common_stability_attribute])*
impl<'a, P> DoubleEndedIterator for $forward_iterator<'a, P>
where
P: Pattern<'a, Searcher: DoubleEndedSearcher<'a>>,
{
#[inline]
fn next_back(&mut self) -> Option<$iterty> {
self.0.next_back()
}
}
$(#[$common_stability_attribute])*
impl<'a, P> DoubleEndedIterator for $reverse_iterator<'a, P>
where
P: Pattern<'a, Searcher: DoubleEndedSearcher<'a>>,
{
#[inline]
fn next_back(&mut self) -> Option<$iterty> {
self.0.next()
}
}
};
{
single ended; with $(#[$common_stability_attribute:meta])*,
$forward_iterator:ident,
$reverse_iterator:ident, $iterty:ty
} => {}
}
derive_pattern_clone!{
clone SplitInternal
with |s| SplitInternal { matcher: s.matcher.clone(), ..*s }
}
struct SplitInternal<'a, P: Pattern<'a>> {
start: usize,
end: usize,
matcher: P::Searcher,
allow_trailing_empty: bool,
finished: bool,
}
impl<'a, P> fmt::Debug for SplitInternal<'a, P>
where
P: Pattern<'a, Searcher: fmt::Debug>,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("SplitInternal")
.field("start", &self.start)
.field("end", &self.end)
.field("matcher", &self.matcher)
.field("allow_trailing_empty", &self.allow_trailing_empty)
.field("finished", &self.finished)
.finish()
}
}
impl<'a, P: Pattern<'a>> SplitInternal<'a, P> {
#[inline]
fn get_end(&mut self) -> Option<&'a str> {
if !self.finished && (self.allow_trailing_empty || self.end - self.start > 0) {
self.finished = true;
unsafe {
let string = self.matcher.haystack().get_unchecked(self.start..self.end);
Some(string)
}
} else {
None
}
}
#[inline]
fn next(&mut self) -> Option<&'a str> {
if self.finished { return None }
let haystack = self.matcher.haystack();
match self.matcher.next_match() {
Some((a, b)) => unsafe {
let elt = haystack.get_unchecked(self.start..a);
self.start = b;
Some(elt)
},
None => self.get_end(),
}
}
#[inline]
fn next_back(&mut self) -> Option<&'a str>
where P::Searcher: ReverseSearcher<'a>
{
if self.finished { return None }
if !self.allow_trailing_empty {
self.allow_trailing_empty = true;
match self.next_back() {
Some(elt) if !elt.is_empty() => return Some(elt),
_ => if self.finished { return None }
}
}
let haystack = self.matcher.haystack();
match self.matcher.next_match_back() {
Some((a, b)) => unsafe {
let elt = haystack.get_unchecked(b..self.end);
self.end = a;
Some(elt)
},
None => unsafe {
self.finished = true;
Some(haystack.get_unchecked(self.start..self.end))
},
}
}
}
generate_pattern_iterators! {
forward:
/// Created with the method [`split`].
///
/// [`split`]: ../../std/primitive.str.html#method.split
struct Split;
reverse:
/// Created with the method [`rsplit`].
///
/// [`rsplit`]: ../../std/primitive.str.html#method.rsplit
struct RSplit;
stability:
#[stable(feature = "rust1", since = "1.0.0")]
internal:
SplitInternal yielding (&'a str);
delegate double ended;
}
generate_pattern_iterators! {
forward:
/// Created with the method [`split_terminator`].
///
/// [`split_terminator`]: ../../std/primitive.str.html#method.split_terminator
struct SplitTerminator;
reverse:
/// Created with the method [`rsplit_terminator`].
///
/// [`rsplit_terminator`]: ../../std/primitive.str.html#method.rsplit_terminator
struct RSplitTerminator;
stability:
#[stable(feature = "rust1", since = "1.0.0")]
internal:
SplitInternal yielding (&'a str);
delegate double ended;
}
derive_pattern_clone!{
clone SplitNInternal
with |s| SplitNInternal { iter: s.iter.clone(), ..*s }
}
struct SplitNInternal<'a, P: Pattern<'a>> {
iter: SplitInternal<'a, P>,
/// The number of splits remaining
count: usize,
}
impl<'a, P> fmt::Debug for SplitNInternal<'a, P>
where
P: Pattern<'a, Searcher: fmt::Debug>,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("SplitNInternal")
.field("iter", &self.iter)
.field("count", &self.count)
.finish()
}
}
impl<'a, P: Pattern<'a>> SplitNInternal<'a, P> {
#[inline]
fn next(&mut self) -> Option<&'a str> {
match self.count {
0 => None,
1 => { self.count = 0; self.iter.get_end() }
_ => { self.count -= 1; self.iter.next() }
}
}
#[inline]
fn next_back(&mut self) -> Option<&'a str>
where P::Searcher: ReverseSearcher<'a>
{
match self.count {
0 => None,
1 => { self.count = 0; self.iter.get_end() }
_ => { self.count -= 1; self.iter.next_back() }
}
}
}
generate_pattern_iterators! {
forward:
/// Created with the method [`splitn`].
///
/// [`splitn`]: ../../std/primitive.str.html#method.splitn
struct SplitN;
reverse:
/// Created with the method [`rsplitn`].
///
/// [`rsplitn`]: ../../std/primitive.str.html#method.rsplitn
struct RSplitN;
stability:
#[stable(feature = "rust1", since = "1.0.0")]
internal:
SplitNInternal yielding (&'a str);
delegate single ended;
}
derive_pattern_clone!{
clone MatchIndicesInternal
with |s| MatchIndicesInternal(s.0.clone())
}
struct MatchIndicesInternal<'a, P: Pattern<'a>>(P::Searcher);
impl<'a, P> fmt::Debug for MatchIndicesInternal<'a, P>
where
P: Pattern<'a, Searcher: fmt::Debug>,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple("MatchIndicesInternal")
.field(&self.0)
.finish()
}
}
impl<'a, P: Pattern<'a>> MatchIndicesInternal<'a, P> {
#[inline]
fn next(&mut self) -> Option<(usize, &'a str)> {
self.0.next_match().map(|(start, end)| unsafe {
(start, self.0.haystack().get_unchecked(start..end))
})
}
#[inline]
fn next_back(&mut self) -> Option<(usize, &'a str)>
where P::Searcher: ReverseSearcher<'a>
{
self.0.next_match_back().map(|(start, end)| unsafe {
(start, self.0.haystack().get_unchecked(start..end))
})
}
}
generate_pattern_iterators! {
forward:
/// Created with the method [`match_indices`].
///
/// [`match_indices`]: ../../std/primitive.str.html#method.match_indices
struct MatchIndices;
reverse:
/// Created with the method [`rmatch_indices`].
///
/// [`rmatch_indices`]: ../../std/primitive.str.html#method.rmatch_indices
struct RMatchIndices;
stability:
#[stable(feature = "str_match_indices", since = "1.5.0")]
internal:
MatchIndicesInternal yielding ((usize, &'a str));
delegate double ended;
}
derive_pattern_clone!{
clone MatchesInternal
with |s| MatchesInternal(s.0.clone())
}
struct MatchesInternal<'a, P: Pattern<'a>>(P::Searcher);
impl<'a, P> fmt::Debug for MatchesInternal<'a, P>
where
P: Pattern<'a, Searcher: fmt::Debug>,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_tuple("MatchesInternal")
.field(&self.0)
.finish()
}
}
impl<'a, P: Pattern<'a>> MatchesInternal<'a, P> {
#[inline]
fn next(&mut self) -> Option<&'a str> {
self.0.next_match().map(|(a, b)| unsafe {
// Indices are known to be on utf8 boundaries
self.0.haystack().get_unchecked(a..b)
})
}
#[inline]
fn next_back(&mut self) -> Option<&'a str>
where P::Searcher: ReverseSearcher<'a>
{
self.0.next_match_back().map(|(a, b)| unsafe {
// Indices are known to be on utf8 boundaries
self.0.haystack().get_unchecked(a..b)
})
}
}
generate_pattern_iterators! {
forward:
/// Created with the method [`matches`].
///
/// [`matches`]: ../../std/primitive.str.html#method.matches
struct Matches;
reverse:
/// Created with the method [`rmatches`].
///
/// [`rmatches`]: ../../std/primitive.str.html#method.rmatches
struct RMatches;
stability:
#[stable(feature = "str_matches", since = "1.2.0")]
internal:
MatchesInternal yielding (&'a str);
delegate double ended;
}
/// An iterator over the lines of a string, as string slices.
///
/// This struct is created with the [`lines`] method on [`str`].
/// See its documentation for more.
///
/// [`lines`]: ../../std/primitive.str.html#method.lines
/// [`str`]: ../../std/primitive.str.html
#[stable(feature = "rust1", since = "1.0.0")]
#[derive(Clone, Debug)]
pub struct Lines<'a>(Map<SplitTerminator<'a, char>, LinesAnyMap>);
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> Iterator for Lines<'a> {
type Item = &'a str;
#[inline]
fn next(&mut self) -> Option<&'a str> {
self.0.next()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.0.size_hint()
}
#[inline]
fn last(mut self) -> Option<&'a str> {
self.next_back()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> DoubleEndedIterator for Lines<'a> {
#[inline]
fn next_back(&mut self) -> Option<&'a str> {
self.0.next_back()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl FusedIterator for Lines<'_> {}
/// Created with the method [`lines_any`].
///
/// [`lines_any`]: ../../std/primitive.str.html#method.lines_any
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_deprecated(since = "1.4.0", reason = "use lines()/Lines instead now")]
#[derive(Clone, Debug)]
#[allow(deprecated)]
pub struct LinesAny<'a>(Lines<'a>);
impl_fn_for_zst! {
/// A nameable, cloneable fn type
#[derive(Clone)]
struct LinesAnyMap impl<'a> Fn = |line: &'a str| -> &'a str {
let l = line.len();
if l > 0 && line.as_bytes()[l - 1] == b'\r' { &line[0 .. l - 1] }
else { line }
};
}
#[stable(feature = "rust1", since = "1.0.0")]
#[allow(deprecated)]
impl<'a> Iterator for LinesAny<'a> {
type Item = &'a str;
#[inline]
fn next(&mut self) -> Option<&'a str> {
self.0.next()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.0.size_hint()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
#[allow(deprecated)]
impl<'a> DoubleEndedIterator for LinesAny<'a> {
#[inline]
fn next_back(&mut self) -> Option<&'a str> {
self.0.next_back()
}
}
#[stable(feature = "fused", since = "1.26.0")]
#[allow(deprecated)]
impl FusedIterator for LinesAny<'_> {}
/*
Section: UTF-8 validation
*/
// use truncation to fit u64 into usize
const NONASCII_MASK: usize = 0x80808080_80808080u64 as usize;
/// Returns `true` if any byte in the word `x` is nonascii (>= 128).
#[inline]
fn contains_nonascii(x: usize) -> bool {
(x & NONASCII_MASK) != 0
}
/// Walks through `v` checking that it's a valid UTF-8 sequence,
/// returning `Ok(())` in that case, or, if it is invalid, `Err(err)`.
#[inline]
fn run_utf8_validation(v: &[u8]) -> Result<(), Utf8Error> {
let mut index = 0;
let len = v.len();
let usize_bytes = mem::size_of::<usize>();
let ascii_block_size = 2 * usize_bytes;
let blocks_end = if len >= ascii_block_size { len - ascii_block_size + 1 } else { 0 };
let align = v.as_ptr().align_offset(usize_bytes);
while index < len {
let old_offset = index;
macro_rules! err {
($error_len: expr) => {
return Err(Utf8Error {
valid_up_to: old_offset,
error_len: $error_len,
})
}
}
macro_rules! next { () => {{
index += 1;
// we needed data, but there was none: error!
if index >= len {
err!(None)
}
v[index]
}}}
let first = v[index];
if first >= 128 {
let w = UTF8_CHAR_WIDTH[first as usize];
// 2-byte encoding is for codepoints \u{0080} to \u{07ff}
// first C2 80 last DF BF
// 3-byte encoding is for codepoints \u{0800} to \u{ffff}
// first E0 A0 80 last EF BF BF
// excluding surrogates codepoints \u{d800} to \u{dfff}
// ED A0 80 to ED BF BF
// 4-byte encoding is for codepoints \u{1000}0 to \u{10ff}ff
// first F0 90 80 80 last F4 8F BF BF
//
// Use the UTF-8 syntax from the RFC
//
// https://tools.ietf.org/html/rfc3629
// UTF8-1 = %x00-7F
// UTF8-2 = %xC2-DF UTF8-tail
// UTF8-3 = %xE0 %xA0-BF UTF8-tail / %xE1-EC 2( UTF8-tail ) /
// %xED %x80-9F UTF8-tail / %xEE-EF 2( UTF8-tail )
// UTF8-4 = %xF0 %x90-BF 2( UTF8-tail ) / %xF1-F3 3( UTF8-tail ) /
// %xF4 %x80-8F 2( UTF8-tail )
match w {
2 => if next!() & !CONT_MASK != TAG_CONT_U8 {
err!(Some(1))
},
3 => {
match (first, next!()) {
(0xE0 , 0xA0 ..= 0xBF) |
(0xE1 ..= 0xEC, 0x80 ..= 0xBF) |
(0xED , 0x80 ..= 0x9F) |
(0xEE ..= 0xEF, 0x80 ..= 0xBF) => {}
_ => err!(Some(1))
}
if next!() & !CONT_MASK != TAG_CONT_U8 {
err!(Some(2))
}
}
4 => {
match (first, next!()) {
(0xF0 , 0x90 ..= 0xBF) |
(0xF1 ..= 0xF3, 0x80 ..= 0xBF) |
(0xF4 , 0x80 ..= 0x8F) => {}
_ => err!(Some(1))
}
if next!() & !CONT_MASK != TAG_CONT_U8 {
err!(Some(2))
}
if next!() & !CONT_MASK != TAG_CONT_U8 {
err!(Some(3))
}
}
_ => err!(Some(1))
}
index += 1;
} else {
// Ascii case, try to skip forward quickly.
// When the pointer is aligned, read 2 words of data per iteration
// until we find a word containing a non-ascii byte.
if align != usize::max_value() && align.wrapping_sub(index) % usize_bytes == 0 {
let ptr = v.as_ptr();
while index < blocks_end {
unsafe {
let block = ptr.add(index) as *const usize;
// break if there is a nonascii byte
let zu = contains_nonascii(*block);
let zv = contains_nonascii(*block.offset(1));
if zu | zv {
break;
}
}
index += ascii_block_size;
}
// step from the point where the wordwise loop stopped
while index < len && v[index] < 128 {
index += 1;
}
} else {
index += 1;
}
}
}
Ok(())
}
// https://tools.ietf.org/html/rfc3629
static UTF8_CHAR_WIDTH: [u8; 256] = [
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // 0x1F
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // 0x3F
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // 0x5F
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, // 0x7F
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 0x9F
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, // 0xBF
0,0,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, // 0xDF
3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3, // 0xEF
4,4,4,4,4,0,0,0,0,0,0,0,0,0,0,0, // 0xFF
];
/// Given a first byte, determines how many bytes are in this UTF-8 character.
#[unstable(feature = "str_internals", issue = "0")]
#[inline]
pub fn utf8_char_width(b: u8) -> usize {
UTF8_CHAR_WIDTH[b as usize] as usize
}
/// Mask of the value bits of a continuation byte.
const CONT_MASK: u8 = 0b0011_1111;
/// Value of the tag bits (tag mask is !CONT_MASK) of a continuation byte.
const TAG_CONT_U8: u8 = 0b1000_0000;
/*
Section: Trait implementations
*/
mod traits {
use crate::cmp::Ordering;
use crate::ops;
use crate::slice::{self, SliceIndex};
/// Implements ordering of strings.
///
/// Strings are ordered lexicographically by their byte values. This orders Unicode code
/// points based on their positions in the code charts. This is not necessarily the same as
/// "alphabetical" order, which varies by language and locale. Sorting strings according to
/// culturally-accepted standards requires locale-specific data that is outside the scope of
/// the `str` type.
#[stable(feature = "rust1", since = "1.0.0")]
impl Ord for str {
#[inline]
fn cmp(&self, other: &str) -> Ordering {
self.as_bytes().cmp(other.as_bytes())
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl PartialEq for str {
#[inline]
fn eq(&self, other: &str) -> bool {
self.as_bytes() == other.as_bytes()
}
#[inline]
fn ne(&self, other: &str) -> bool { !(*self).eq(other) }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl Eq for str {}
/// Implements comparison operations on strings.
///
/// Strings are compared lexicographically by their byte values. This compares Unicode code
/// points based on their positions in the code charts. This is not necessarily the same as
/// "alphabetical" order, which varies by language and locale. Comparing strings according to
/// culturally-accepted standards requires locale-specific data that is outside the scope of
/// the `str` type.
#[stable(feature = "rust1", since = "1.0.0")]
impl PartialOrd for str {
#[inline]
fn partial_cmp(&self, other: &str) -> Option<Ordering> {
Some(self.cmp(other))
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<I> ops::Index<I> for str
where
I: SliceIndex<str>,
{
type Output = I::Output;
#[inline]
fn index(&self, index: I) -> &I::Output {
index.index(self)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<I> ops::IndexMut<I> for str
where
I: SliceIndex<str>,
{
#[inline]
fn index_mut(&mut self, index: I) -> &mut I::Output {
index.index_mut(self)
}
}
#[inline(never)]
#[cold]
fn str_index_overflow_fail() -> ! {
panic!("attempted to index str up to maximum usize");
}
/// Implements substring slicing with syntax `&self[..]` or `&mut self[..]`.
///
/// Returns a slice of the whole string, i.e., returns `&self` or `&mut
/// self`. Equivalent to `&self[0 .. len]` or `&mut self[0 .. len]`. Unlike
/// other indexing operations, this can never panic.
///
/// This operation is `O(1)`.
///
/// Prior to 1.20.0, these indexing operations were still supported by
/// direct implementation of `Index` and `IndexMut`.
///
/// Equivalent to `&self[0 .. len]` or `&mut self[0 .. len]`.
#[stable(feature = "str_checked_slicing", since = "1.20.0")]
impl SliceIndex<str> for ops::RangeFull {
type Output = str;
#[inline]
fn get(self, slice: &str) -> Option<&Self::Output> {
Some(slice)
}
#[inline]
fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
Some(slice)
}
#[inline]
unsafe fn get_unchecked(self, slice: &str) -> &Self::Output {
slice
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output {
slice
}
#[inline]
fn index(self, slice: &str) -> &Self::Output {
slice
}
#[inline]
fn index_mut(self, slice: &mut str) -> &mut Self::Output {
slice
}
}
/// Implements substring slicing with syntax `&self[begin .. end]` or `&mut
/// self[begin .. end]`.
///
/// Returns a slice of the given string from the byte range
/// [`begin`, `end`).
///
/// This operation is `O(1)`.
///
/// Prior to 1.20.0, these indexing operations were still supported by
/// direct implementation of `Index` and `IndexMut`.
///
/// # Panics
///
/// Panics if `begin` or `end` does not point to the starting byte offset of
/// a character (as defined by `is_char_boundary`), if `begin > end`, or if
/// `end > len`.
///
/// # Examples
///
/// ```
/// let s = "Löwe 老虎 Léopard";
/// assert_eq!(&s[0 .. 1], "L");
///
/// assert_eq!(&s[1 .. 9], "öwe 老");
///
/// // these will panic:
/// // byte 2 lies within `ö`:
/// // &s[2 ..3];
///
/// // byte 8 lies within `老`
/// // &s[1 .. 8];
///
/// // byte 100 is outside the string
/// // &s[3 .. 100];
/// ```
#[stable(feature = "str_checked_slicing", since = "1.20.0")]
impl SliceIndex<str> for ops::Range<usize> {
type Output = str;
#[inline]
fn get(self, slice: &str) -> Option<&Self::Output> {
if self.start <= self.end &&
slice.is_char_boundary(self.start) &&
slice.is_char_boundary(self.end) {
Some(unsafe { self.get_unchecked(slice) })
} else {
None
}
}
#[inline]
fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
if self.start <= self.end &&
slice.is_char_boundary(self.start) &&
slice.is_char_boundary(self.end) {
Some(unsafe { self.get_unchecked_mut(slice) })
} else {
None
}
}
#[inline]
unsafe fn get_unchecked(self, slice: &str) -> &Self::Output {
let ptr = slice.as_ptr().add(self.start);
let len = self.end - self.start;
super::from_utf8_unchecked(slice::from_raw_parts(ptr, len))
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output {
let ptr = slice.as_mut_ptr().add(self.start);
let len = self.end - self.start;
super::from_utf8_unchecked_mut(slice::from_raw_parts_mut(ptr, len))
}
#[inline]
fn index(self, slice: &str) -> &Self::Output {
let (start, end) = (self.start, self.end);
self.get(slice).unwrap_or_else(|| super::slice_error_fail(slice, start, end))
}
#[inline]
fn index_mut(self, slice: &mut str) -> &mut Self::Output {
// is_char_boundary checks that the index is in [0, .len()]
// cannot reuse `get` as above, because of NLL trouble
if self.start <= self.end &&
slice.is_char_boundary(self.start) &&
slice.is_char_boundary(self.end) {
unsafe { self.get_unchecked_mut(slice) }
} else {
super::slice_error_fail(slice, self.start, self.end)
}
}
}
/// Implements substring slicing with syntax `&self[.. end]` or `&mut
/// self[.. end]`.
///
/// Returns a slice of the given string from the byte range [`0`, `end`).
/// Equivalent to `&self[0 .. end]` or `&mut self[0 .. end]`.
///
/// This operation is `O(1)`.
///
/// Prior to 1.20.0, these indexing operations were still supported by
/// direct implementation of `Index` and `IndexMut`.
///
/// # Panics
///
/// Panics if `end` does not point to the starting byte offset of a
/// character (as defined by `is_char_boundary`), or if `end > len`.
#[stable(feature = "str_checked_slicing", since = "1.20.0")]
impl SliceIndex<str> for ops::RangeTo<usize> {
type Output = str;
#[inline]
fn get(self, slice: &str) -> Option<&Self::Output> {
if slice.is_char_boundary(self.end) {
Some(unsafe { self.get_unchecked(slice) })
} else {
None
}
}
#[inline]
fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
if slice.is_char_boundary(self.end) {
Some(unsafe { self.get_unchecked_mut(slice) })
} else {
None
}
}
#[inline]
unsafe fn get_unchecked(self, slice: &str) -> &Self::Output {
let ptr = slice.as_ptr();
super::from_utf8_unchecked(slice::from_raw_parts(ptr, self.end))
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output {
let ptr = slice.as_mut_ptr();
super::from_utf8_unchecked_mut(slice::from_raw_parts_mut(ptr, self.end))
}
#[inline]
fn index(self, slice: &str) -> &Self::Output {
let end = self.end;
self.get(slice).unwrap_or_else(|| super::slice_error_fail(slice, 0, end))
}
#[inline]
fn index_mut(self, slice: &mut str) -> &mut Self::Output {
// is_char_boundary checks that the index is in [0, .len()]
if slice.is_char_boundary(self.end) {
unsafe { self.get_unchecked_mut(slice) }
} else {
super::slice_error_fail(slice, 0, self.end)
}
}
}
/// Implements substring slicing with syntax `&self[begin ..]` or `&mut
/// self[begin ..]`.
///
/// Returns a slice of the given string from the byte range [`begin`,
/// `len`). Equivalent to `&self[begin .. len]` or `&mut self[begin ..
/// len]`.
///
/// This operation is `O(1)`.
///
/// Prior to 1.20.0, these indexing operations were still supported by
/// direct implementation of `Index` and `IndexMut`.
///
/// # Panics
///
/// Panics if `begin` does not point to the starting byte offset of
/// a character (as defined by `is_char_boundary`), or if `begin >= len`.
#[stable(feature = "str_checked_slicing", since = "1.20.0")]
impl SliceIndex<str> for ops::RangeFrom<usize> {
type Output = str;
#[inline]
fn get(self, slice: &str) -> Option<&Self::Output> {
if slice.is_char_boundary(self.start) {
Some(unsafe { self.get_unchecked(slice) })
} else {
None
}
}
#[inline]
fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
if slice.is_char_boundary(self.start) {
Some(unsafe { self.get_unchecked_mut(slice) })
} else {
None
}
}
#[inline]
unsafe fn get_unchecked(self, slice: &str) -> &Self::Output {
let ptr = slice.as_ptr().add(self.start);
let len = slice.len() - self.start;
super::from_utf8_unchecked(slice::from_raw_parts(ptr, len))
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output {
let ptr = slice.as_mut_ptr().add(self.start);
let len = slice.len() - self.start;
super::from_utf8_unchecked_mut(slice::from_raw_parts_mut(ptr, len))
}
#[inline]
fn index(self, slice: &str) -> &Self::Output {
let (start, end) = (self.start, slice.len());
self.get(slice).unwrap_or_else(|| super::slice_error_fail(slice, start, end))
}
#[inline]
fn index_mut(self, slice: &mut str) -> &mut Self::Output {
// is_char_boundary checks that the index is in [0, .len()]
if slice.is_char_boundary(self.start) {
unsafe { self.get_unchecked_mut(slice) }
} else {
super::slice_error_fail(slice, self.start, slice.len())
}
}
}
/// Implements substring slicing with syntax `&self[begin ..= end]` or `&mut
/// self[begin ..= end]`.
///
/// Returns a slice of the given string from the byte range
/// [`begin`, `end`]. Equivalent to `&self [begin .. end + 1]` or `&mut
/// self[begin .. end + 1]`, except if `end` has the maximum value for
/// `usize`.
///
/// This operation is `O(1)`.
///
/// # Panics
///
/// Panics if `begin` does not point to the starting byte offset of
/// a character (as defined by `is_char_boundary`), if `end` does not point
/// to the ending byte offset of a character (`end + 1` is either a starting
/// byte offset or equal to `len`), if `begin > end`, or if `end >= len`.
#[stable(feature = "inclusive_range", since = "1.26.0")]
impl SliceIndex<str> for ops::RangeInclusive<usize> {
type Output = str;
#[inline]
fn get(self, slice: &str) -> Option<&Self::Output> {
if *self.end() == usize::max_value() { None }
else { (*self.start()..self.end()+1).get(slice) }
}
#[inline]
fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
if *self.end() == usize::max_value() { None }
else { (*self.start()..self.end()+1).get_mut(slice) }
}
#[inline]
unsafe fn get_unchecked(self, slice: &str) -> &Self::Output {
(*self.start()..self.end()+1).get_unchecked(slice)
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output {
(*self.start()..self.end()+1).get_unchecked_mut(slice)
}
#[inline]
fn index(self, slice: &str) -> &Self::Output {
if *self.end() == usize::max_value() { str_index_overflow_fail(); }
(*self.start()..self.end()+1).index(slice)
}
#[inline]
fn index_mut(self, slice: &mut str) -> &mut Self::Output {
if *self.end() == usize::max_value() { str_index_overflow_fail(); }
(*self.start()..self.end()+1).index_mut(slice)
}
}
/// Implements substring slicing with syntax `&self[..= end]` or `&mut
/// self[..= end]`.
///
/// Returns a slice of the given string from the byte range [0, `end`].
/// Equivalent to `&self [0 .. end + 1]`, except if `end` has the maximum
/// value for `usize`.
///
/// This operation is `O(1)`.
///
/// # Panics
///
/// Panics if `end` does not point to the ending byte offset of a character
/// (`end + 1` is either a starting byte offset as defined by
/// `is_char_boundary`, or equal to `len`), or if `end >= len`.
#[stable(feature = "inclusive_range", since = "1.26.0")]
impl SliceIndex<str> for ops::RangeToInclusive<usize> {
type Output = str;
#[inline]
fn get(self, slice: &str) -> Option<&Self::Output> {
if self.end == usize::max_value() { None }
else { (..self.end+1).get(slice) }
}
#[inline]
fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
if self.end == usize::max_value() { None }
else { (..self.end+1).get_mut(slice) }
}
#[inline]
unsafe fn get_unchecked(self, slice: &str) -> &Self::Output {
(..self.end+1).get_unchecked(slice)
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: &mut str) -> &mut Self::Output {
(..self.end+1).get_unchecked_mut(slice)
}
#[inline]
fn index(self, slice: &str) -> &Self::Output {
if self.end == usize::max_value() { str_index_overflow_fail(); }
(..self.end+1).index(slice)
}
#[inline]
fn index_mut(self, slice: &mut str) -> &mut Self::Output {
if self.end == usize::max_value() { str_index_overflow_fail(); }
(..self.end+1).index_mut(slice)
}
}
}
// truncate `&str` to length at most equal to `max`
// return `true` if it were truncated, and the new str.
fn truncate_to_char_boundary(s: &str, mut max: usize) -> (bool, &str) {
if max >= s.len() {
(false, s)
} else {
while !s.is_char_boundary(max) {
max -= 1;
}
(true, &s[..max])
}
}
#[inline(never)]
#[cold]
fn slice_error_fail(s: &str, begin: usize, end: usize) -> ! {
const MAX_DISPLAY_LENGTH: usize = 256;
let (truncated, s_trunc) = truncate_to_char_boundary(s, MAX_DISPLAY_LENGTH);
let ellipsis = if truncated { "[...]" } else { "" };
// 1. out of bounds
if begin > s.len() || end > s.len() {
let oob_index = if begin > s.len() { begin } else { end };
panic!("byte index {} is out of bounds of `{}`{}", oob_index, s_trunc, ellipsis);
}
// 2. begin <= end
assert!(begin <= end, "begin <= end ({} <= {}) when slicing `{}`{}",
begin, end, s_trunc, ellipsis);
// 3. character boundary
let index = if !s.is_char_boundary(begin) { begin } else { end };
// find the character
let mut char_start = index;
while !s.is_char_boundary(char_start) {
char_start -= 1;
}
// `char_start` must be less than len and a char boundary
let ch = s[char_start..].chars().next().unwrap();
let char_range = char_start .. char_start + ch.len_utf8();
panic!("byte index {} is not a char boundary; it is inside {:?} (bytes {:?}) of `{}`{}",
index, ch, char_range, s_trunc, ellipsis);
}
#[lang = "str"]
#[cfg(not(test))]
impl str {
/// Returns the length of `self`.
///
/// This length is 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 len = "foo".len();
/// assert_eq!(3, len);
///
/// assert_eq!("ƒoo".len(), 4); // fancy f!
/// assert_eq!("ƒoo".chars().count(), 3);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub const fn len(&self) -> usize {
self.as_bytes().len()
}
/// Returns `true` if `self` has a length of zero bytes.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let s = "";
/// assert!(s.is_empty());
///
/// let s = "not empty";
/// assert!(!s.is_empty());
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub const fn is_empty(&self) -> bool {
self.len() == 0
}
/// Checks that `index`-th byte lies at the start and/or end of a
/// UTF-8 code point sequence.
///
/// The start and end of the string (when `index == self.len()`) are
/// considered to be
/// boundaries.
///
/// Returns `false` if `index` is greater than `self.len()`.
///
/// # Examples
///
/// ```
/// let s = "Löwe 老虎 Léopard";
/// assert!(s.is_char_boundary(0));
/// // start of `老`
/// assert!(s.is_char_boundary(6));
/// assert!(s.is_char_boundary(s.len()));
///
/// // second byte of `ö`
/// assert!(!s.is_char_boundary(2));
///
/// // third byte of `老`
/// assert!(!s.is_char_boundary(8));
/// ```
#[stable(feature = "is_char_boundary", since = "1.9.0")]
#[inline]
pub fn is_char_boundary(&self, index: usize) -> bool {
// 0 and len are always ok.
// Test for 0 explicitly so that it can optimize out the check
// easily and skip reading string data for that case.
if index == 0 || index == self.len() { return true; }
match self.as_bytes().get(index) {
None => false,
// This is bit magic equivalent to: b < 128 || b >= 192
Some(&b) => (b as i8) >= -0x40,
}
}
/// Converts a string slice to a byte slice. To convert the byte slice back
/// into a string slice, use the [`str::from_utf8`] function.
///
/// [`str::from_utf8`]: ./str/fn.from_utf8.html
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let bytes = "bors".as_bytes();
/// assert_eq!(b"bors", bytes);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline(always)]
// SAFETY: const sound because we transmute two types with the same layout
#[allow(unused_attributes)]
#[allow_internal_unstable(const_fn_union)]
pub const fn as_bytes(&self) -> &[u8] {
#[repr(C)]
union Slices<'a> {
str: &'a str,
slice: &'a [u8],
}
unsafe { Slices { str: self }.slice }
}
/// Converts a mutable string slice to a mutable byte slice. To convert the
/// mutable byte slice back into a mutable string slice, use the
/// [`str::from_utf8_mut`] function.
///
/// [`str::from_utf8_mut`]: ./str/fn.from_utf8_mut.html
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let mut s = String::from("Hello");
/// let bytes = unsafe { s.as_bytes_mut() };
///
/// assert_eq!(b"Hello", bytes);
/// ```
///
/// Mutability:
///
/// ```
/// let mut s = String::from("🗻∈🌏");
///
/// unsafe {
/// let bytes = s.as_bytes_mut();
///
/// bytes[0] = 0xF0;
/// bytes[1] = 0x9F;
/// bytes[2] = 0x8D;
/// bytes[3] = 0x94;
/// }
///
/// assert_eq!("🍔∈🌏", s);
/// ```
#[stable(feature = "str_mut_extras", since = "1.20.0")]
#[inline(always)]
pub unsafe fn as_bytes_mut(&mut self) -> &mut [u8] {
&mut *(self as *mut str as *mut [u8])
}
/// Converts a string slice to a raw pointer.
///
/// As string slices are a slice of bytes, the raw pointer points to a
/// [`u8`]. This pointer will be pointing to the first byte of the string
/// slice.
///
/// The caller must ensure that the returned pointer is never written to.
/// If you need to mutate the contents of the string slice, use [`as_mut_ptr`].
///
/// [`u8`]: primitive.u8.html
/// [`as_mut_ptr`]: #method.as_mut_ptr
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let s = "Hello";
/// let ptr = s.as_ptr();
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub const fn as_ptr(&self) -> *const u8 {
self as *const str as *const u8
}
/// Converts a mutable string slice to a raw pointer.
///
/// As string slices are a slice of bytes, the raw pointer points to a
/// [`u8`]. This pointer will be pointing to the first byte of the string
/// slice.
///
/// It is your responsibility to make sure that the string slice only gets
/// modified in a way that it remains valid UTF-8.
///
/// [`u8`]: primitive.u8.html
#[stable(feature = "str_as_mut_ptr", since = "1.36.0")]
#[inline]
pub fn as_mut_ptr(&mut self) -> *mut u8 {
self as *mut str as *mut u8
}
/// Returns a subslice of `str`.
///
/// This is the non-panicking alternative to indexing the `str`. Returns
/// [`None`] whenever equivalent indexing operation would panic.
///
/// [`None`]: option/enum.Option.html#variant.None
///
/// # Examples
///
/// ```
/// let v = String::from("🗻∈🌏");
///
/// assert_eq!(Some("🗻"), v.get(0..4));
///
/// // indices not on UTF-8 sequence boundaries
/// assert!(v.get(1..).is_none());
/// assert!(v.get(..8).is_none());
///
/// // out of bounds
/// assert!(v.get(..42).is_none());
/// ```
#[stable(feature = "str_checked_slicing", since = "1.20.0")]
#[inline]
pub fn get<I: SliceIndex<str>>(&self, i: I) -> Option<&I::Output> {
i.get(self)
}
/// Returns a mutable subslice of `str`.
///
/// This is the non-panicking alternative to indexing the `str`. Returns
/// [`None`] whenever equivalent indexing operation would panic.
///
/// [`None`]: option/enum.Option.html#variant.None
///
/// # Examples
///
/// ```
/// let mut v = String::from("hello");
/// // correct length
/// assert!(v.get_mut(0..5).is_some());
/// // out of bounds
/// assert!(v.get_mut(..42).is_none());
/// assert_eq!(Some("he"), v.get_mut(0..2).map(|v| &*v));
///
/// assert_eq!("hello", v);
/// {
/// let s = v.get_mut(0..2);
/// let s = s.map(|s| {
/// s.make_ascii_uppercase();
/// &*s
/// });
/// assert_eq!(Some("HE"), s);
/// }
/// assert_eq!("HEllo", v);
/// ```
#[stable(feature = "str_checked_slicing", since = "1.20.0")]
#[inline]
pub fn get_mut<I: SliceIndex<str>>(&mut self, i: I) -> Option<&mut I::Output> {
i.get_mut(self)
}
/// Returns a unchecked subslice of `str`.
///
/// This is the unchecked alternative to indexing the `str`.
///
/// # Safety
///
/// Callers of this function are responsible that these preconditions are
/// satisfied:
///
/// * The starting index must come before the ending index;
/// * Indexes must be within bounds of the original slice;
/// * Indexes must lie on UTF-8 sequence boundaries.
///
/// Failing that, the returned string slice may reference invalid memory or
/// violate the invariants communicated by the `str` type.
///
/// # Examples
///
/// ```
/// let v = "🗻∈🌏";
/// unsafe {
/// assert_eq!("🗻", v.get_unchecked(0..4));
/// assert_eq!("∈", v.get_unchecked(4..7));
/// assert_eq!("🌏", v.get_unchecked(7..11));
/// }
/// ```
#[stable(feature = "str_checked_slicing", since = "1.20.0")]
#[inline]
pub unsafe fn get_unchecked<I: SliceIndex<str>>(&self, i: I) -> &I::Output {
i.get_unchecked(self)
}
/// Returns a mutable, unchecked subslice of `str`.
///
/// This is the unchecked alternative to indexing the `str`.
///
/// # Safety
///
/// Callers of this function are responsible that these preconditions are
/// satisfied:
///
/// * The starting index must come before the ending index;
/// * Indexes must be within bounds of the original slice;
/// * Indexes must lie on UTF-8 sequence boundaries.
///
/// Failing that, the returned string slice may reference invalid memory or
/// violate the invariants communicated by the `str` type.
///
/// # Examples
///
/// ```
/// let mut v = String::from("🗻∈🌏");
/// unsafe {
/// assert_eq!("🗻", v.get_unchecked_mut(0..4));
/// assert_eq!("∈", v.get_unchecked_mut(4..7));
/// assert_eq!("🌏", v.get_unchecked_mut(7..11));
/// }
/// ```
#[stable(feature = "str_checked_slicing", since = "1.20.0")]
#[inline]
pub unsafe fn get_unchecked_mut<I: SliceIndex<str>>(&mut self, i: I) -> &mut I::Output {
i.get_unchecked_mut(self)
}
/// Creates a string slice from another string slice, bypassing safety
/// checks.
///
/// This is generally not recommended, use with caution! For a safe
/// alternative see [`str`] and [`Index`].
///
/// [`str`]: primitive.str.html
/// [`Index`]: ops/trait.Index.html
///
/// This new slice goes from `begin` to `end`, including `begin` but
/// excluding `end`.
///
/// To get a mutable string slice instead, see the
/// [`slice_mut_unchecked`] method.
///
/// [`slice_mut_unchecked`]: #method.slice_mut_unchecked
///
/// # Safety
///
/// Callers of this function are responsible that three preconditions are
/// satisfied:
///
/// * `begin` must come before `end`.
/// * `begin` and `end` must be byte positions within the string slice.
/// * `begin` and `end` must lie on UTF-8 sequence boundaries.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let s = "Löwe 老虎 Léopard";
///
/// unsafe {
/// assert_eq!("Löwe 老虎 Léopard", s.slice_unchecked(0, 21));
/// }
///
/// let s = "Hello, world!";
///
/// unsafe {
/// assert_eq!("world", s.slice_unchecked(7, 12));
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_deprecated(since = "1.29.0", reason = "use `get_unchecked(begin..end)` instead")]
#[inline]
pub unsafe fn slice_unchecked(&self, begin: usize, end: usize) -> &str {
(begin..end).get_unchecked(self)
}
/// Creates a string slice from another string slice, bypassing safety
/// checks.
/// This is generally not recommended, use with caution! For a safe
/// alternative see [`str`] and [`IndexMut`].
///
/// [`str`]: primitive.str.html
/// [`IndexMut`]: ops/trait.IndexMut.html
///
/// This new slice goes from `begin` to `end`, including `begin` but
/// excluding `end`.
///
/// To get an immutable string slice instead, see the
/// [`slice_unchecked`] method.
///
/// [`slice_unchecked`]: #method.slice_unchecked
///
/// # Safety
///
/// Callers of this function are responsible that three preconditions are
/// satisfied:
///
/// * `begin` must come before `end`.
/// * `begin` and `end` must be byte positions within the string slice.
/// * `begin` and `end` must lie on UTF-8 sequence boundaries.
#[stable(feature = "str_slice_mut", since = "1.5.0")]
#[rustc_deprecated(since = "1.29.0", reason = "use `get_unchecked_mut(begin..end)` instead")]
#[inline]
pub unsafe fn slice_mut_unchecked(&mut self, begin: usize, end: usize) -> &mut str {
(begin..end).get_unchecked_mut(self)
}
/// Divide one string slice into two at an index.
///
/// The argument, `mid`, should be a byte offset from the start of the
/// string. It must also be on the boundary of a UTF-8 code point.
///
/// The two slices returned go from the start of the string slice to `mid`,
/// and from `mid` to the end of the string slice.
///
/// To get mutable string slices instead, see the [`split_at_mut`]
/// method.
///
/// [`split_at_mut`]: #method.split_at_mut
///
/// # Panics
///
/// Panics if `mid` is not on a UTF-8 code point boundary, or if it is
/// beyond the last code point of the string slice.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let s = "Per Martin-Löf";
///
/// let (first, last) = s.split_at(3);
///
/// assert_eq!("Per", first);
/// assert_eq!(" Martin-Löf", last);
/// ```
#[inline]
#[stable(feature = "str_split_at", since = "1.4.0")]
pub fn split_at(&self, mid: usize) -> (&str, &str) {
// is_char_boundary checks that the index is in [0, .len()]
if self.is_char_boundary(mid) {
unsafe {
(self.get_unchecked(0..mid),
self.get_unchecked(mid..self.len()))
}
} else {
slice_error_fail(self, 0, mid)
}
}
/// Divide one mutable string slice into two at an index.
///
/// The argument, `mid`, should be a byte offset from the start of the
/// string. It must also be on the boundary of a UTF-8 code point.
///
/// The two slices returned go from the start of the string slice to `mid`,
/// and from `mid` to the end of the string slice.
///
/// To get immutable string slices instead, see the [`split_at`] method.
///
/// [`split_at`]: #method.split_at
///
/// # Panics
///
/// Panics if `mid` is not on a UTF-8 code point boundary, or if it is
/// beyond the last code point of the string slice.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let mut s = "Per Martin-Löf".to_string();
/// {
/// let (first, last) = s.split_at_mut(3);
/// first.make_ascii_uppercase();
/// assert_eq!("PER", first);
/// assert_eq!(" Martin-Löf", last);
/// }
/// assert_eq!("PER Martin-Löf", s);
/// ```
#[inline]
#[stable(feature = "str_split_at", since = "1.4.0")]
pub fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str) {
// is_char_boundary checks that the index is in [0, .len()]
if self.is_char_boundary(mid) {
let len = self.len();
let ptr = self.as_mut_ptr();
unsafe {
(from_utf8_unchecked_mut(slice::from_raw_parts_mut(ptr, mid)),
from_utf8_unchecked_mut(slice::from_raw_parts_mut(
ptr.add(mid),
len - mid
)))
}
} else {
slice_error_fail(self, 0, mid)
}
}
/// Returns an iterator over the [`char`]s of a string slice.
///
/// As a string slice consists of valid UTF-8, we can iterate through a
/// string slice by [`char`]. This method returns such an iterator.
///
/// It's important to remember that [`char`] represents a Unicode Scalar
/// Value, and may not match your idea of what a 'character' is. Iteration
/// over grapheme clusters may be what you actually want.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let word = "goodbye";
///
/// let count = word.chars().count();
/// assert_eq!(7, count);
///
/// let mut chars = word.chars();
///
/// assert_eq!(Some('g'), chars.next());
/// assert_eq!(Some('o'), chars.next());
/// assert_eq!(Some('o'), chars.next());
/// assert_eq!(Some('d'), chars.next());
/// assert_eq!(Some('b'), chars.next());
/// assert_eq!(Some('y'), chars.next());
/// assert_eq!(Some('e'), chars.next());
///
/// assert_eq!(None, chars.next());
/// ```
///
/// Remember, [`char`]s may not match your human intuition about characters:
///
/// ```
/// let y = "y̆";
///
/// let mut chars = y.chars();
///
/// assert_eq!(Some('y'), chars.next()); // not 'y̆'
/// assert_eq!(Some('\u{0306}'), chars.next());
///
/// assert_eq!(None, chars.next());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn chars(&self) -> Chars<'_> {
Chars{iter: self.as_bytes().iter()}
}
/// Returns an iterator over the [`char`]s of a string slice, and their
/// positions.
///
/// As a string slice consists of valid UTF-8, we can iterate through a
/// string slice by [`char`]. This method returns an iterator of both
/// these [`char`]s, as well as their byte positions.
///
/// The iterator yields tuples. The position is first, the [`char`] is
/// second.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let word = "goodbye";
///
/// let count = word.char_indices().count();
/// assert_eq!(7, count);
///
/// let mut char_indices = word.char_indices();
///
/// assert_eq!(Some((0, 'g')), char_indices.next());
/// assert_eq!(Some((1, 'o')), char_indices.next());
/// assert_eq!(Some((2, 'o')), char_indices.next());
/// assert_eq!(Some((3, 'd')), char_indices.next());
/// assert_eq!(Some((4, 'b')), char_indices.next());
/// assert_eq!(Some((5, 'y')), char_indices.next());
/// assert_eq!(Some((6, 'e')), char_indices.next());
///
/// assert_eq!(None, char_indices.next());
/// ```
///
/// Remember, [`char`]s may not match your human intuition about characters:
///
/// ```
/// let yes = "y̆es";
///
/// let mut char_indices = yes.char_indices();
///
/// assert_eq!(Some((0, 'y')), char_indices.next()); // not (0, 'y̆')
/// assert_eq!(Some((1, '\u{0306}')), char_indices.next());
///
/// // note the 3 here - the last character took up two bytes
/// assert_eq!(Some((3, 'e')), char_indices.next());
/// assert_eq!(Some((4, 's')), char_indices.next());
///
/// assert_eq!(None, char_indices.next());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn char_indices(&self) -> CharIndices<'_> {
CharIndices { front_offset: 0, iter: self.chars() }
}
/// An iterator over the bytes of a string slice.
///
/// As a string slice consists of a sequence of bytes, we can iterate
/// through a string slice by byte. This method returns such an iterator.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let mut bytes = "bors".bytes();
///
/// assert_eq!(Some(b'b'), bytes.next());
/// assert_eq!(Some(b'o'), bytes.next());
/// assert_eq!(Some(b'r'), bytes.next());
/// assert_eq!(Some(b's'), bytes.next());
///
/// assert_eq!(None, bytes.next());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn bytes(&self) -> Bytes<'_> {
Bytes(self.as_bytes().iter().cloned())
}
/// Splits a string slice by whitespace.
///
/// The iterator returned will return string slices that are sub-slices of
/// the original string slice, separated by any amount of whitespace.
///
/// 'Whitespace' is defined according to the terms of the Unicode Derived
/// Core Property `White_Space`. If you only want to split on ASCII whitespace
/// instead, use [`split_ascii_whitespace`].
///
/// [`split_ascii_whitespace`]: #method.split_ascii_whitespace
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let mut iter = "A few words".split_whitespace();
///
/// assert_eq!(Some("A"), iter.next());
/// assert_eq!(Some("few"), iter.next());
/// assert_eq!(Some("words"), iter.next());
///
/// assert_eq!(None, iter.next());
/// ```
///
/// All kinds of whitespace are considered:
///
/// ```
/// let mut iter = " Mary had\ta\u{2009}little \n\t lamb".split_whitespace();
/// assert_eq!(Some("Mary"), iter.next());
/// assert_eq!(Some("had"), iter.next());
/// assert_eq!(Some("a"), iter.next());
/// assert_eq!(Some("little"), iter.next());
/// assert_eq!(Some("lamb"), iter.next());
///
/// assert_eq!(None, iter.next());
/// ```
#[stable(feature = "split_whitespace", since = "1.1.0")]
#[inline]
pub fn split_whitespace(&self) -> SplitWhitespace<'_> {
SplitWhitespace { inner: self.split(IsWhitespace).filter(IsNotEmpty) }
}
/// Splits a string slice by ASCII whitespace.
///
/// The iterator returned will return string slices that are sub-slices of
/// the original string slice, separated by any amount of ASCII whitespace.
///
/// To split by Unicode `Whitespace` instead, use [`split_whitespace`].
///
/// [`split_whitespace`]: #method.split_whitespace
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let mut iter = "A few words".split_ascii_whitespace();
///
/// assert_eq!(Some("A"), iter.next());
/// assert_eq!(Some("few"), iter.next());
/// assert_eq!(Some("words"), iter.next());
///
/// assert_eq!(None, iter.next());
/// ```
///
/// All kinds of ASCII whitespace are considered:
///
/// ```
/// let mut iter = " Mary had\ta little \n\t lamb".split_ascii_whitespace();
/// assert_eq!(Some("Mary"), iter.next());
/// assert_eq!(Some("had"), iter.next());
/// assert_eq!(Some("a"), iter.next());
/// assert_eq!(Some("little"), iter.next());
/// assert_eq!(Some("lamb"), iter.next());
///
/// assert_eq!(None, iter.next());
/// ```
#[stable(feature = "split_ascii_whitespace", since = "1.34.0")]
#[inline]
pub fn split_ascii_whitespace(&self) -> SplitAsciiWhitespace<'_> {
let inner = self
.as_bytes()
.split(IsAsciiWhitespace)
.filter(BytesIsNotEmpty)
.map(UnsafeBytesToStr);
SplitAsciiWhitespace { inner }
}
/// An iterator over the lines of a string, as string slices.
///
/// Lines are ended with either a newline (`\n`) or a carriage return with
/// a line feed (`\r\n`).
///
/// The final line ending is optional.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let text = "foo\r\nbar\n\nbaz\n";
/// let mut lines = text.lines();
///
/// assert_eq!(Some("foo"), lines.next());
/// assert_eq!(Some("bar"), lines.next());
/// assert_eq!(Some(""), lines.next());
/// assert_eq!(Some("baz"), lines.next());
///
/// assert_eq!(None, lines.next());
/// ```
///
/// The final line ending isn't required:
///
/// ```
/// let text = "foo\nbar\n\r\nbaz";
/// let mut lines = text.lines();
///
/// assert_eq!(Some("foo"), lines.next());
/// assert_eq!(Some("bar"), lines.next());
/// assert_eq!(Some(""), lines.next());
/// assert_eq!(Some("baz"), lines.next());
///
/// assert_eq!(None, lines.next());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn lines(&self) -> Lines<'_> {
Lines(self.split_terminator('\n').map(LinesAnyMap))
}
/// An iterator over the lines of a string.
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_deprecated(since = "1.4.0", reason = "use lines() instead now")]
#[inline]
#[allow(deprecated)]
pub fn lines_any(&self) -> LinesAny<'_> {
LinesAny(self.lines())
}
/// Returns an iterator of `u16` over the string encoded as UTF-16.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let text = "Zażółć gęślą jaźń";
///
/// let utf8_len = text.len();
/// let utf16_len = text.encode_utf16().count();
///
/// assert!(utf16_len <= utf8_len);
/// ```
#[stable(feature = "encode_utf16", since = "1.8.0")]
pub fn encode_utf16(&self) -> EncodeUtf16<'_> {
EncodeUtf16 { chars: self.chars(), extra: 0 }
}
/// Returns `true` if the given pattern matches a sub-slice of
/// this string slice.
///
/// Returns `false` if it does not.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let bananas = "bananas";
///
/// assert!(bananas.contains("nana"));
/// assert!(!bananas.contains("apples"));
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn contains<'a, P: Pattern<'a>>(&'a self, pat: P) -> bool {
pat.is_contained_in(self)
}
/// Returns `true` if the given pattern matches a prefix of this
/// string slice.
///
/// Returns `false` if it does not.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let bananas = "bananas";
///
/// assert!(bananas.starts_with("bana"));
/// assert!(!bananas.starts_with("nana"));
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn starts_with<'a, P: Pattern<'a>>(&'a self, pat: P) -> bool {
pat.is_prefix_of(self)
}
/// Returns `true` if the given pattern matches a suffix of this
/// string slice.
///
/// Returns `false` if it does not.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let bananas = "bananas";
///
/// assert!(bananas.ends_with("anas"));
/// assert!(!bananas.ends_with("nana"));
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn ends_with<'a, P>(&'a self, pat: P) -> bool
where
P: Pattern<'a, Searcher: ReverseSearcher<'a>>,
{
pat.is_suffix_of(self)
}
/// Returns the byte index of the first character of this string slice that
/// matches the pattern.
///
/// Returns [`None`] if the pattern doesn't match.
///
/// The pattern can be a `&str`, [`char`], or a closure that determines if
/// a character matches.
///
/// [`None`]: option/enum.Option.html#variant.None
///
/// # Examples
///
/// Simple patterns:
///
/// ```
/// let s = "Löwe 老虎 Léopard";
///
/// assert_eq!(s.find('L'), Some(0));
/// assert_eq!(s.find('é'), Some(14));
/// assert_eq!(s.find("Léopard"), Some(13));
/// ```
///
/// More complex patterns using point-free style and closures:
///
/// ```
/// let s = "Löwe 老虎 Léopard";
///
/// assert_eq!(s.find(char::is_whitespace), Some(5));
/// assert_eq!(s.find(char::is_lowercase), Some(1));
/// assert_eq!(s.find(|c: char| c.is_whitespace() || c.is_lowercase()), Some(1));
/// assert_eq!(s.find(|c: char| (c < 'o') && (c > 'a')), Some(4));
/// ```
///
/// Not finding the pattern:
///
/// ```
/// let s = "Löwe 老虎 Léopard";
/// let x: &[_] = &['1', '2'];
///
/// assert_eq!(s.find(x), None);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn find<'a, P: Pattern<'a>>(&'a self, pat: P) -> Option<usize> {
pat.into_searcher(self).next_match().map(|(i, _)| i)
}
/// Returns the byte index of the last character of this string slice that
/// matches the pattern.
///
/// Returns [`None`] if the pattern doesn't match.
///
/// The pattern can be a `&str`, [`char`], or a closure that determines if
/// a character matches.
///
/// [`None`]: option/enum.Option.html#variant.None
///
/// # Examples
///
/// Simple patterns:
///
/// ```
/// let s = "Löwe 老虎 Léopard";
///
/// assert_eq!(s.rfind('L'), Some(13));
/// assert_eq!(s.rfind('é'), Some(14));
/// ```
///
/// More complex patterns with closures:
///
/// ```
/// let s = "Löwe 老虎 Léopard";
///
/// assert_eq!(s.rfind(char::is_whitespace), Some(12));
/// assert_eq!(s.rfind(char::is_lowercase), Some(20));
/// ```
///
/// Not finding the pattern:
///
/// ```
/// let s = "Löwe 老虎 Léopard";
/// let x: &[_] = &['1', '2'];
///
/// assert_eq!(s.rfind(x), None);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn rfind<'a, P>(&'a self, pat: P) -> Option<usize>
where
P: Pattern<'a, Searcher: ReverseSearcher<'a>>,
{
pat.into_searcher(self).next_match_back().map(|(i, _)| i)
}
/// An iterator over substrings of this string slice, separated by
/// characters matched by a pattern.
///
/// The pattern can be any type that implements the Pattern trait. Notable
/// examples are `&str`, [`char`], and closures that determines the split.
///
/// # Iterator behavior
///
/// The returned iterator will be a [`DoubleEndedIterator`] if the pattern
/// allows a reverse search and forward/reverse search yields the same
/// elements. This is true for, e.g., [`char`], but not for `&str`.
///
/// [`DoubleEndedIterator`]: iter/trait.DoubleEndedIterator.html
///
/// If the pattern allows a reverse search but its results might differ
/// from a forward search, the [`rsplit`] method can be used.
///
/// [`rsplit`]: #method.rsplit
///
/// # Examples
///
/// Simple patterns:
///
/// ```
/// let v: Vec<&str> = "Mary had a little lamb".split(' ').collect();
/// assert_eq!(v, ["Mary", "had", "a", "little", "lamb"]);
///
/// let v: Vec<&str> = "".split('X').collect();
/// assert_eq!(v, [""]);
///
/// let v: Vec<&str> = "lionXXtigerXleopard".split('X').collect();
/// assert_eq!(v, ["lion", "", "tiger", "leopard"]);
///
/// let v: Vec<&str> = "lion::tiger::leopard".split("::").collect();
/// assert_eq!(v, ["lion", "tiger", "leopard"]);
///
/// let v: Vec<&str> = "abc1def2ghi".split(char::is_numeric).collect();
/// assert_eq!(v, ["abc", "def", "ghi"]);
///
/// let v: Vec<&str> = "lionXtigerXleopard".split(char::is_uppercase).collect();
/// assert_eq!(v, ["lion", "tiger", "leopard"]);
/// ```
///
/// A more complex pattern, using a closure:
///
/// ```
/// let v: Vec<&str> = "abc1defXghi".split(|c| c == '1' || c == 'X').collect();
/// assert_eq!(v, ["abc", "def", "ghi"]);
/// ```
///
/// If a string contains multiple contiguous separators, you will end up
/// with empty strings in the output:
///
/// ```
/// let x = "||||a||b|c".to_string();
/// let d: Vec<_> = x.split('|').collect();
///
/// assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);
/// ```
///
/// Contiguous separators are separated by the empty string.
///
/// ```
/// let x = "(///)".to_string();
/// let d: Vec<_> = x.split('/').collect();
///
/// assert_eq!(d, &["(", "", "", ")"]);
/// ```
///
/// Separators at the start or end of a string are neighbored
/// by empty strings.
///
/// ```
/// let d: Vec<_> = "010".split("0").collect();
/// assert_eq!(d, &["", "1", ""]);
/// ```
///
/// When the empty string is used as a separator, it separates
/// every character in the string, along with the beginning
/// and end of the string.
///
/// ```
/// let f: Vec<_> = "rust".split("").collect();
/// assert_eq!(f, &["", "r", "u", "s", "t", ""]);
/// ```
///
/// Contiguous separators can lead to possibly surprising behavior
/// when whitespace is used as the separator. This code is correct:
///
/// ```
/// let x = " a b c".to_string();
/// let d: Vec<_> = x.split(' ').collect();
///
/// assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);
/// ```
///
/// It does _not_ give you:
///
/// ```,ignore
/// assert_eq!(d, &["a", "b", "c"]);
/// ```
///
/// Use [`split_whitespace`] for this behavior.
///
/// [`split_whitespace`]: #method.split_whitespace
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn split<'a, P: Pattern<'a>>(&'a self, pat: P) -> Split<'a, P> {
Split(SplitInternal {
start: 0,
end: self.len(),
matcher: pat.into_searcher(self),
allow_trailing_empty: true,
finished: false,
})
}
/// An iterator over substrings of the given string slice, separated by
/// characters matched by a pattern and yielded in reverse order.
///
/// The pattern can be any type that implements the Pattern trait. Notable
/// examples are `&str`, [`char`], and closures that determines the split.
///
/// # Iterator behavior
///
/// The returned iterator requires that the pattern supports a reverse
/// search, and it will be a [`DoubleEndedIterator`] if a forward/reverse
/// search yields the same elements.
///
/// [`DoubleEndedIterator`]: iter/trait.DoubleEndedIterator.html
///
/// For iterating from the front, the [`split`] method can be used.
///
/// [`split`]: #method.split
///
/// # Examples
///
/// Simple patterns:
///
/// ```
/// let v: Vec<&str> = "Mary had a little lamb".rsplit(' ').collect();
/// assert_eq!(v, ["lamb", "little", "a", "had", "Mary"]);
///
/// let v: Vec<&str> = "".rsplit('X').collect();
/// assert_eq!(v, [""]);
///
/// let v: Vec<&str> = "lionXXtigerXleopard".rsplit('X').collect();
/// assert_eq!(v, ["leopard", "tiger", "", "lion"]);
///
/// let v: Vec<&str> = "lion::tiger::leopard".rsplit("::").collect();
/// assert_eq!(v, ["leopard", "tiger", "lion"]);
/// ```
///
/// A more complex pattern, using a closure:
///
/// ```
/// let v: Vec<&str> = "abc1defXghi".rsplit(|c| c == '1' || c == 'X').collect();
/// assert_eq!(v, ["ghi", "def", "abc"]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn rsplit<'a, P>(&'a self, pat: P) -> RSplit<'a, P>
where
P: Pattern<'a, Searcher: ReverseSearcher<'a>>,
{
RSplit(self.split(pat).0)
}
/// An iterator over substrings of the given string slice, separated by
/// characters matched by a pattern.
///
/// The pattern can be any type that implements the Pattern trait. Notable
/// examples are `&str`, [`char`], and closures that determines the split.
///
/// Equivalent to [`split`], except that the trailing substring
/// is skipped if empty.
///
/// [`split`]: #method.split
///
/// This method can be used for string data that is _terminated_,
/// rather than _separated_ by a pattern.
///
/// # Iterator behavior
///
/// The returned iterator will be a [`DoubleEndedIterator`] if the pattern
/// allows a reverse search and forward/reverse search yields the same
/// elements. This is true for, e.g., [`char`], but not for `&str`.
///
/// [`DoubleEndedIterator`]: iter/trait.DoubleEndedIterator.html
///
/// If the pattern allows a reverse search but its results might differ
/// from a forward search, the [`rsplit_terminator`] method can be used.
///
/// [`rsplit_terminator`]: #method.rsplit_terminator
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let v: Vec<&str> = "A.B.".split_terminator('.').collect();
/// assert_eq!(v, ["A", "B"]);
///
/// let v: Vec<&str> = "A..B..".split_terminator(".").collect();
/// assert_eq!(v, ["A", "", "B", ""]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn split_terminator<'a, P: Pattern<'a>>(&'a self, pat: P) -> SplitTerminator<'a, P> {
SplitTerminator(SplitInternal {
allow_trailing_empty: false,
..self.split(pat).0
})
}
/// An iterator over substrings of `self`, separated by characters
/// matched by a pattern and yielded in reverse order.
///
/// The pattern can be any type that implements the Pattern trait. Notable
/// examples are `&str`, [`char`], and closures that determines the split.
/// Additional libraries might provide more complex patterns like
/// regular expressions.
///
/// Equivalent to [`split`], except that the trailing substring is
/// skipped if empty.
///
/// [`split`]: #method.split
///
/// This method can be used for string data that is _terminated_,
/// rather than _separated_ by a pattern.
///
/// # Iterator behavior
///
/// The returned iterator requires that the pattern supports a
/// reverse search, and it will be double ended if a forward/reverse
/// search yields the same elements.
///
/// For iterating from the front, the [`split_terminator`] method can be
/// used.
///
/// [`split_terminator`]: #method.split_terminator
///
/// # Examples
///
/// ```
/// let v: Vec<&str> = "A.B.".rsplit_terminator('.').collect();
/// assert_eq!(v, ["B", "A"]);
///
/// let v: Vec<&str> = "A..B..".rsplit_terminator(".").collect();
/// assert_eq!(v, ["", "B", "", "A"]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn rsplit_terminator<'a, P>(&'a self, pat: P) -> RSplitTerminator<'a, P>
where
P: Pattern<'a, Searcher: ReverseSearcher<'a>>,
{
RSplitTerminator(self.split_terminator(pat).0)
}
/// An iterator over substrings of the given string slice, separated by a
/// pattern, restricted to returning at most `n` items.
///
/// If `n` substrings are returned, the last substring (the `n`th substring)
/// will contain the remainder of the string.
///
/// The pattern can be any type that implements the Pattern trait. Notable
/// examples are `&str`, [`char`], and closures that determines the split.
///
/// # Iterator behavior
///
/// The returned iterator will not be double ended, because it is
/// not efficient to support.
///
/// If the pattern allows a reverse search, the [`rsplitn`] method can be
/// used.
///
/// [`rsplitn`]: #method.rsplitn
///
/// # Examples
///
/// Simple patterns:
///
/// ```
/// let v: Vec<&str> = "Mary had a little lambda".splitn(3, ' ').collect();
/// assert_eq!(v, ["Mary", "had", "a little lambda"]);
///
/// let v: Vec<&str> = "lionXXtigerXleopard".splitn(3, "X").collect();
/// assert_eq!(v, ["lion", "", "tigerXleopard"]);
///
/// let v: Vec<&str> = "abcXdef".splitn(1, 'X').collect();
/// assert_eq!(v, ["abcXdef"]);
///
/// let v: Vec<&str> = "".splitn(1, 'X').collect();
/// assert_eq!(v, [""]);
/// ```
///
/// A more complex pattern, using a closure:
///
/// ```
/// let v: Vec<&str> = "abc1defXghi".splitn(2, |c| c == '1' || c == 'X').collect();
/// assert_eq!(v, ["abc", "defXghi"]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn splitn<'a, P: Pattern<'a>>(&'a self, n: usize, pat: P) -> SplitN<'a, P> {
SplitN(SplitNInternal {
iter: self.split(pat).0,
count: n,
})
}
/// An iterator over substrings of this string slice, separated by a
/// pattern, starting from the end of the string, restricted to returning
/// at most `n` items.
///
/// If `n` substrings are returned, the last substring (the `n`th substring)
/// will contain the remainder of the string.
///
/// The pattern can be any type that implements the Pattern trait. Notable
/// examples are `&str`, [`char`], and closures that determines the split.
///
/// # Iterator behavior
///
/// The returned iterator will not be double ended, because it is not
/// efficient to support.
///
/// For splitting from the front, the [`splitn`] method can be used.
///
/// [`splitn`]: #method.splitn
///
/// # Examples
///
/// Simple patterns:
///
/// ```
/// let v: Vec<&str> = "Mary had a little lamb".rsplitn(3, ' ').collect();
/// assert_eq!(v, ["lamb", "little", "Mary had a"]);
///
/// let v: Vec<&str> = "lionXXtigerXleopard".rsplitn(3, 'X').collect();
/// assert_eq!(v, ["leopard", "tiger", "lionX"]);
///
/// let v: Vec<&str> = "lion::tiger::leopard".rsplitn(2, "::").collect();
/// assert_eq!(v, ["leopard", "lion::tiger"]);
/// ```
///
/// A more complex pattern, using a closure:
///
/// ```
/// let v: Vec<&str> = "abc1defXghi".rsplitn(2, |c| c == '1' || c == 'X').collect();
/// assert_eq!(v, ["ghi", "abc1def"]);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn rsplitn<'a, P>(&'a self, n: usize, pat: P) -> RSplitN<'a, P>
where
P: Pattern<'a, Searcher: ReverseSearcher<'a>>,
{
RSplitN(self.splitn(n, pat).0)
}
/// An iterator over the disjoint matches of a pattern within the given string
/// slice.
///
/// The pattern can be any type that implements the Pattern trait. Notable
/// examples are `&str`, [`char`], and closures that determines the split.
///
/// # Iterator behavior
///
/// The returned iterator will be a [`DoubleEndedIterator`] if the pattern
/// allows a reverse search and forward/reverse search yields the same
/// elements. This is true for, e.g., [`char`], but not for `&str`.
///
/// [`DoubleEndedIterator`]: iter/trait.DoubleEndedIterator.html
///
/// If the pattern allows a reverse search but its results might differ
/// from a forward search, the [`rmatches`] method can be used.
///
/// [`rmatches`]: #method.rmatches
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let v: Vec<&str> = "abcXXXabcYYYabc".matches("abc").collect();
/// assert_eq!(v, ["abc", "abc", "abc"]);
///
/// let v: Vec<&str> = "1abc2abc3".matches(char::is_numeric).collect();
/// assert_eq!(v, ["1", "2", "3"]);
/// ```
#[stable(feature = "str_matches", since = "1.2.0")]
#[inline]
pub fn matches<'a, P: Pattern<'a>>(&'a self, pat: P) -> Matches<'a, P> {
Matches(MatchesInternal(pat.into_searcher(self)))
}
/// An iterator over the disjoint matches of a pattern within this string slice,
/// yielded in reverse order.
///
/// The pattern can be a `&str`, [`char`], or a closure that determines if
/// a character matches.
///
/// # Iterator behavior
///
/// The returned iterator requires that the pattern supports a reverse
/// search, and it will be a [`DoubleEndedIterator`] if a forward/reverse
/// search yields the same elements.
///
/// [`DoubleEndedIterator`]: iter/trait.DoubleEndedIterator.html
///
/// For iterating from the front, the [`matches`] method can be used.
///
/// [`matches`]: #method.matches
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let v: Vec<&str> = "abcXXXabcYYYabc".rmatches("abc").collect();
/// assert_eq!(v, ["abc", "abc", "abc"]);
///
/// let v: Vec<&str> = "1abc2abc3".rmatches(char::is_numeric).collect();
/// assert_eq!(v, ["3", "2", "1"]);
/// ```
#[stable(feature = "str_matches", since = "1.2.0")]
#[inline]
pub fn rmatches<'a, P>(&'a self, pat: P) -> RMatches<'a, P>
where
P: Pattern<'a, Searcher: ReverseSearcher<'a>>,
{
RMatches(self.matches(pat).0)
}
/// An iterator over the disjoint matches of a pattern within this string
/// slice as well as the index that the match starts at.
///
/// For matches of `pat` within `self` that overlap, only the indices
/// corresponding to the first match are returned.
///
/// The pattern can be a `&str`, [`char`], or a closure that determines
/// if a character matches.
///
/// # Iterator behavior
///
/// The returned iterator will be a [`DoubleEndedIterator`] if the pattern
/// allows a reverse search and forward/reverse search yields the same
/// elements. This is true for, e.g., [`char`], but not for `&str`.
///
/// [`DoubleEndedIterator`]: iter/trait.DoubleEndedIterator.html
///
/// If the pattern allows a reverse search but its results might differ
/// from a forward search, the [`rmatch_indices`] method can be used.
///
/// [`rmatch_indices`]: #method.rmatch_indices
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let v: Vec<_> = "abcXXXabcYYYabc".match_indices("abc").collect();
/// assert_eq!(v, [(0, "abc"), (6, "abc"), (12, "abc")]);
///
/// let v: Vec<_> = "1abcabc2".match_indices("abc").collect();
/// assert_eq!(v, [(1, "abc"), (4, "abc")]);
///
/// let v: Vec<_> = "ababa".match_indices("aba").collect();
/// assert_eq!(v, [(0, "aba")]); // only the first `aba`
/// ```
#[stable(feature = "str_match_indices", since = "1.5.0")]
#[inline]
pub fn match_indices<'a, P: Pattern<'a>>(&'a self, pat: P) -> MatchIndices<'a, P> {
MatchIndices(MatchIndicesInternal(pat.into_searcher(self)))
}
/// An iterator over the disjoint matches of a pattern within `self`,
/// yielded in reverse order along with the index of the match.
///
/// For matches of `pat` within `self` that overlap, only the indices
/// corresponding to the last match are returned.
///
/// The pattern can be a `&str`, [`char`], or a closure that determines if a
/// character matches.
///
/// # Iterator behavior
///
/// The returned iterator requires that the pattern supports a reverse
/// search, and it will be a [`DoubleEndedIterator`] if a forward/reverse
/// search yields the same elements.
///
/// [`DoubleEndedIterator`]: iter/trait.DoubleEndedIterator.html
///
/// For iterating from the front, the [`match_indices`] method can be used.
///
/// [`match_indices`]: #method.match_indices
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let v: Vec<_> = "abcXXXabcYYYabc".rmatch_indices("abc").collect();
/// assert_eq!(v, [(12, "abc"), (6, "abc"), (0, "abc")]);
///
/// let v: Vec<_> = "1abcabc2".rmatch_indices("abc").collect();
/// assert_eq!(v, [(4, "abc"), (1, "abc")]);
///
/// let v: Vec<_> = "ababa".rmatch_indices("aba").collect();
/// assert_eq!(v, [(2, "aba")]); // only the last `aba`
/// ```
#[stable(feature = "str_match_indices", since = "1.5.0")]
#[inline]
pub fn rmatch_indices<'a, P>(&'a self, pat: P) -> RMatchIndices<'a, P>
where
P: Pattern<'a, Searcher: ReverseSearcher<'a>>,
{
RMatchIndices(self.match_indices(pat).0)
}
/// Returns a string slice with leading and trailing whitespace removed.
///
/// 'Whitespace' is defined according to the terms of the Unicode Derived
/// Core Property `White_Space`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let s = " Hello\tworld\t";
///
/// assert_eq!("Hello\tworld", s.trim());
/// ```
#[must_use = "this returns the trimmed string as a slice, \
without modifying the original"]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn trim(&self) -> &str {
self.trim_matches(|c: char| c.is_whitespace())
}
/// Returns a string slice with leading whitespace removed.
///
/// 'Whitespace' is defined according to the terms of the Unicode Derived
/// Core Property `White_Space`.
///
/// # Text directionality
///
/// A string is a sequence of bytes. `start` in this context means the first
/// position of that byte string; for a left-to-right language like English or
/// Russian, this will be left side, and for right-to-left languages like
/// Arabic or Hebrew, this will be the right side.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let s = " Hello\tworld\t";
/// assert_eq!("Hello\tworld\t", s.trim_start());
/// ```
///
/// Directionality:
///
/// ```
/// let s = " English ";
/// assert!(Some('E') == s.trim_start().chars().next());
///
/// let s = " עברית ";
/// assert!(Some('ע') == s.trim_start().chars().next());
/// ```
#[must_use = "this returns the trimmed string as a new slice, \
without modifying the original"]
#[stable(feature = "trim_direction", since = "1.30.0")]
pub fn trim_start(&self) -> &str {
self.trim_start_matches(|c: char| c.is_whitespace())
}
/// Returns a string slice with trailing whitespace removed.
///
/// 'Whitespace' is defined according to the terms of the Unicode Derived
/// Core Property `White_Space`.
///
/// # Text directionality
///
/// A string is a sequence of bytes. `end` in this context means the last
/// position of that byte string; for a left-to-right language like English or
/// Russian, this will be right side, and for right-to-left languages like
/// Arabic or Hebrew, this will be the left side.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let s = " Hello\tworld\t";
/// assert_eq!(" Hello\tworld", s.trim_end());
/// ```
///
/// Directionality:
///
/// ```
/// let s = " English ";
/// assert!(Some('h') == s.trim_end().chars().rev().next());
///
/// let s = " עברית ";
/// assert!(Some('ת') == s.trim_end().chars().rev().next());
/// ```
#[must_use = "this returns the trimmed string as a new slice, \
without modifying the original"]
#[stable(feature = "trim_direction", since = "1.30.0")]
pub fn trim_end(&self) -> &str {
self.trim_end_matches(|c: char| c.is_whitespace())
}
/// Returns a string slice with leading whitespace removed.
///
/// 'Whitespace' is defined according to the terms of the Unicode Derived
/// Core Property `White_Space`.
///
/// # Text directionality
///
/// A string is a sequence of bytes. 'Left' in this context means the first
/// position of that byte string; for a language like Arabic or Hebrew
/// which are 'right to left' rather than 'left to right', this will be
/// the _right_ side, not the left.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let s = " Hello\tworld\t";
///
/// assert_eq!("Hello\tworld\t", s.trim_left());
/// ```
///
/// Directionality:
///
/// ```
/// let s = " English";
/// assert!(Some('E') == s.trim_left().chars().next());
///
/// let s = " עברית";
/// assert!(Some('ע') == s.trim_left().chars().next());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_deprecated(
since = "1.33.0",
reason = "superseded by `trim_start`",
suggestion = "trim_start",
)]
pub fn trim_left(&self) -> &str {
self.trim_start()
}
/// Returns a string slice with trailing whitespace removed.
///
/// 'Whitespace' is defined according to the terms of the Unicode Derived
/// Core Property `White_Space`.
///
/// # Text directionality
///
/// A string is a sequence of bytes. 'Right' in this context means the last
/// position of that byte string; for a language like Arabic or Hebrew
/// which are 'right to left' rather than 'left to right', this will be
/// the _left_ side, not the right.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let s = " Hello\tworld\t";
///
/// assert_eq!(" Hello\tworld", s.trim_right());
/// ```
///
/// Directionality:
///
/// ```
/// let s = "English ";
/// assert!(Some('h') == s.trim_right().chars().rev().next());
///
/// let s = "עברית ";
/// assert!(Some('ת') == s.trim_right().chars().rev().next());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_deprecated(
since = "1.33.0",
reason = "superseded by `trim_end`",
suggestion = "trim_end",
)]
pub fn trim_right(&self) -> &str {
self.trim_end()
}
/// Returns a string slice with all prefixes and suffixes that match a
/// pattern repeatedly removed.
///
/// The pattern can be a [`char`] or a closure that determines if a
/// character matches.
///
/// # Examples
///
/// Simple patterns:
///
/// ```
/// assert_eq!("11foo1bar11".trim_matches('1'), "foo1bar");
/// assert_eq!("123foo1bar123".trim_matches(char::is_numeric), "foo1bar");
///
/// let x: &[_] = &['1', '2'];
/// assert_eq!("12foo1bar12".trim_matches(x), "foo1bar");
/// ```
///
/// A more complex pattern, using a closure:
///
/// ```
/// assert_eq!("1foo1barXX".trim_matches(|c| c == '1' || c == 'X'), "foo1bar");
/// ```
#[must_use = "this returns the trimmed string as a new slice, \
without modifying the original"]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn trim_matches<'a, P>(&'a self, pat: P) -> &'a str
where
P: Pattern<'a, Searcher: DoubleEndedSearcher<'a>>,
{
let mut i = 0;
let mut j = 0;
let mut matcher = pat.into_searcher(self);
if let Some((a, b)) = matcher.next_reject() {
i = a;
j = b; // Remember earliest known match, correct it below if
// last match is different
}
if let Some((_, b)) = matcher.next_reject_back() {
j = b;
}
unsafe {
// Searcher is known to return valid indices
self.get_unchecked(i..j)
}
}
/// Returns a string slice with all prefixes that match a pattern
/// repeatedly removed.
///
/// The pattern can be a `&str`, [`char`], or a closure that determines if
/// a character matches.
///
/// # Text directionality
///
/// A string is a sequence of bytes. `start` in this context means the first
/// position of that byte string; for a left-to-right language like English or
/// Russian, this will be left side, and for right-to-left languages like
/// Arabic or Hebrew, this will be the right side.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// assert_eq!("11foo1bar11".trim_start_matches('1'), "foo1bar11");
/// assert_eq!("123foo1bar123".trim_start_matches(char::is_numeric), "foo1bar123");
///
/// let x: &[_] = &['1', '2'];
/// assert_eq!("12foo1bar12".trim_start_matches(x), "foo1bar12");
/// ```
#[must_use = "this returns the trimmed string as a new slice, \
without modifying the original"]
#[stable(feature = "trim_direction", since = "1.30.0")]
pub fn trim_start_matches<'a, P: Pattern<'a>>(&'a self, pat: P) -> &'a str {
let mut i = self.len();
let mut matcher = pat.into_searcher(self);
if let Some((a, _)) = matcher.next_reject() {
i = a;
}
unsafe {
// Searcher is known to return valid indices
self.get_unchecked(i..self.len())
}
}
/// Returns a string slice with all suffixes that match a pattern
/// repeatedly removed.
///
/// The pattern can be a `&str`, [`char`], or a closure that
/// determines if a character matches.
///
/// # Text directionality
///
/// A string is a sequence of bytes. `end` in this context means the last
/// position of that byte string; for a left-to-right language like English or
/// Russian, this will be right side, and for right-to-left languages like
/// Arabic or Hebrew, this will be the left side.
///
/// # Examples
///
/// Simple patterns:
///
/// ```
/// assert_eq!("11foo1bar11".trim_end_matches('1'), "11foo1bar");
/// assert_eq!("123foo1bar123".trim_end_matches(char::is_numeric), "123foo1bar");
///
/// let x: &[_] = &['1', '2'];
/// assert_eq!("12foo1bar12".trim_end_matches(x), "12foo1bar");
/// ```
///
/// A more complex pattern, using a closure:
///
/// ```
/// assert_eq!("1fooX".trim_end_matches(|c| c == '1' || c == 'X'), "1foo");
/// ```
#[must_use = "this returns the trimmed string as a new slice, \
without modifying the original"]
#[stable(feature = "trim_direction", since = "1.30.0")]
pub fn trim_end_matches<'a, P>(&'a self, pat: P) -> &'a str
where
P: Pattern<'a, Searcher: ReverseSearcher<'a>>,
{
let mut j = 0;
let mut matcher = pat.into_searcher(self);
if let Some((_, b)) = matcher.next_reject_back() {
j = b;
}
unsafe {
// Searcher is known to return valid indices
self.get_unchecked(0..j)
}
}
/// Returns a string slice with all prefixes that match a pattern
/// repeatedly removed.
///
/// The pattern can be a `&str`, [`char`], or a closure that determines if
/// a character matches.
///
/// [`char`]: primitive.char.html
///
/// # Text directionality
///
/// A string is a sequence of bytes. 'Left' in this context means the first
/// position of that byte string; for a language like Arabic or Hebrew
/// which are 'right to left' rather than 'left to right', this will be
/// the _right_ side, not the left.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// assert_eq!("11foo1bar11".trim_left_matches('1'), "foo1bar11");
/// assert_eq!("123foo1bar123".trim_left_matches(char::is_numeric), "foo1bar123");
///
/// let x: &[_] = &['1', '2'];
/// assert_eq!("12foo1bar12".trim_left_matches(x), "foo1bar12");
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_deprecated(
since = "1.33.0",
reason = "superseded by `trim_start_matches`",
suggestion = "trim_start_matches",
)]
pub fn trim_left_matches<'a, P: Pattern<'a>>(&'a self, pat: P) -> &'a str {
self.trim_start_matches(pat)
}
/// Returns a string slice with all suffixes that match a pattern
/// repeatedly removed.
///
/// The pattern can be a `&str`, [`char`], or a closure that
/// determines if a character matches.
///
/// [`char`]: primitive.char.html
///
/// # Text directionality
///
/// A string is a sequence of bytes. 'Right' in this context means the last
/// position of that byte string; for a language like Arabic or Hebrew
/// which are 'right to left' rather than 'left to right', this will be
/// the _left_ side, not the right.
///
/// # Examples
///
/// Simple patterns:
///
/// ```
/// assert_eq!("11foo1bar11".trim_right_matches('1'), "11foo1bar");
/// assert_eq!("123foo1bar123".trim_right_matches(char::is_numeric), "123foo1bar");
///
/// let x: &[_] = &['1', '2'];
/// assert_eq!("12foo1bar12".trim_right_matches(x), "12foo1bar");
/// ```
///
/// A more complex pattern, using a closure:
///
/// ```
/// assert_eq!("1fooX".trim_right_matches(|c| c == '1' || c == 'X'), "1foo");
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_deprecated(
since = "1.33.0",
reason = "superseded by `trim_end_matches`",
suggestion = "trim_end_matches",
)]
pub fn trim_right_matches<'a, P>(&'a self, pat: P) -> &'a str
where
P: Pattern<'a, Searcher: ReverseSearcher<'a>>,
{
self.trim_end_matches(pat)
}
/// Parses this string slice into another type.
///
/// Because `parse` is so general, it can cause problems with type
/// inference. As such, `parse` is one of the few times you'll see
/// the syntax affectionately known as the 'turbofish': `::<>`. This
/// helps the inference algorithm understand specifically which type
/// you're trying to parse into.
///
/// `parse` can parse any type that implements the [`FromStr`] trait.
///
/// [`FromStr`]: str/trait.FromStr.html
///
/// # Errors
///
/// Will return [`Err`] if it's not possible to parse this string slice into
/// the desired type.
///
/// [`Err`]: str/trait.FromStr.html#associatedtype.Err
///
/// # Examples
///
/// Basic usage
///
/// ```
/// let four: u32 = "4".parse().unwrap();
///
/// assert_eq!(4, four);
/// ```
///
/// Using the 'turbofish' instead of annotating `four`:
///
/// ```
/// let four = "4".parse::<u32>();
///
/// assert_eq!(Ok(4), four);
/// ```
///
/// Failing to parse:
///
/// ```
/// let nope = "j".parse::<u32>();
///
/// assert!(nope.is_err());
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn parse<F: FromStr>(&self) -> Result<F, F::Err> {
FromStr::from_str(self)
}
/// Checks if all characters in this string are within the ASCII range.
///
/// # Examples
///
/// ```
/// let ascii = "hello!\n";
/// let non_ascii = "Grüße, Jürgen ❤";
///
/// assert!(ascii.is_ascii());
/// assert!(!non_ascii.is_ascii());
/// ```
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[inline]
pub fn is_ascii(&self) -> bool {
// We can treat each byte as character here: all multibyte characters
// start with a byte that is not in the ascii range, so we will stop
// there already.
self.bytes().all(|b| b.is_ascii())
}
/// Checks that two strings are an ASCII case-insensitive match.
///
/// Same as `to_ascii_lowercase(a) == to_ascii_lowercase(b)`,
/// but without allocating and copying temporaries.
///
/// # Examples
///
/// ```
/// assert!("Ferris".eq_ignore_ascii_case("FERRIS"));
/// assert!("Ferrös".eq_ignore_ascii_case("FERRöS"));
/// assert!(!"Ferrös".eq_ignore_ascii_case("FERRÖS"));
/// ```
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[inline]
pub fn eq_ignore_ascii_case(&self, other: &str) -> bool {
self.as_bytes().eq_ignore_ascii_case(other.as_bytes())
}
/// Converts this string to its ASCII upper case equivalent in-place.
///
/// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
/// but non-ASCII letters are unchanged.
///
/// To return a new uppercased value without modifying the existing one, use
/// [`to_ascii_uppercase`].
///
/// [`to_ascii_uppercase`]: #method.to_ascii_uppercase
///
/// # Examples
///
/// ```
/// let mut s = String::from("Grüße, Jürgen ❤");
///
/// s.make_ascii_uppercase();
///
/// assert_eq!("GRüßE, JüRGEN ❤", s);
/// ```
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
pub fn make_ascii_uppercase(&mut self) {
let me = unsafe { self.as_bytes_mut() };
me.make_ascii_uppercase()
}
/// Converts this string to its ASCII lower case equivalent in-place.
///
/// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
/// but non-ASCII letters are unchanged.
///
/// To return a new lowercased value without modifying the existing one, use
/// [`to_ascii_lowercase`].
///
/// [`to_ascii_lowercase`]: #method.to_ascii_lowercase
///
/// # Examples
///
/// ```
/// let mut s = String::from("GRÜßE, JÜRGEN ❤");
///
/// s.make_ascii_lowercase();
///
/// assert_eq!("grÜße, jÜrgen ❤", s);
/// ```
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
pub fn make_ascii_lowercase(&mut self) {
let me = unsafe { self.as_bytes_mut() };
me.make_ascii_lowercase()
}
/// Return an iterator that escapes each char in `self` with [`char::escape_debug`].
///
/// Note: only extended grapheme codepoints that begin the string will be
/// escaped.
///
/// [`char::escape_debug`]: ../std/primitive.char.html#method.escape_debug
///
/// # Examples
///
/// As an iterator:
///
/// ```
/// for c in "❤\n!".escape_debug() {
/// print!("{}", c);
/// }
/// println!();
/// ```
///
/// Using `println!` directly:
///
/// ```
/// println!("{}", "❤\n!".escape_debug());
/// ```
///
///
/// Both are equivalent to:
///
/// ```
/// println!("❤\\n!");
/// ```
///
/// Using `to_string`:
///
/// ```
/// assert_eq!("❤\n!".escape_debug().to_string(), "❤\\n!");
/// ```
#[stable(feature = "str_escape", since = "1.34.0")]
pub fn escape_debug(&self) -> EscapeDebug<'_> {
let mut chars = self.chars();
EscapeDebug {
inner: chars.next()
.map(|first| first.escape_debug_ext(true))
.into_iter()
.flatten()
.chain(chars.flat_map(CharEscapeDebugContinue))
}
}
/// Return an iterator that escapes each char in `self` with [`char::escape_default`].
///
/// [`char::escape_default`]: ../std/primitive.char.html#method.escape_default
///
/// # Examples
///
/// As an iterator:
///
/// ```
/// for c in "❤\n!".escape_default() {
/// print!("{}", c);
/// }
/// println!();
/// ```
///
/// Using `println!` directly:
///
/// ```
/// println!("{}", "❤\n!".escape_default());
/// ```
///
///
/// Both are equivalent to:
///
/// ```
/// println!("\\u{{2764}}\\n!");
/// ```
///
/// Using `to_string`:
///
/// ```
/// assert_eq!("❤\n!".escape_default().to_string(), "\\u{2764}\\n!");
/// ```
#[stable(feature = "str_escape", since = "1.34.0")]
pub fn escape_default(&self) -> EscapeDefault<'_> {
EscapeDefault { inner: self.chars().flat_map(CharEscapeDefault) }
}
/// Return an iterator that escapes each char in `self` with [`char::escape_unicode`].
///
/// [`char::escape_unicode`]: ../std/primitive.char.html#method.escape_unicode
///
/// # Examples
///
/// As an iterator:
///
/// ```
/// for c in "❤\n!".escape_unicode() {
/// print!("{}", c);
/// }
/// println!();
/// ```
///
/// Using `println!` directly:
///
/// ```
/// println!("{}", "❤\n!".escape_unicode());
/// ```
///
///
/// Both are equivalent to:
///
/// ```
/// println!("\\u{{2764}}\\u{{a}}\\u{{21}}");
/// ```
///
/// Using `to_string`:
///
/// ```
/// assert_eq!("❤\n!".escape_unicode().to_string(), "\\u{2764}\\u{a}\\u{21}");
/// ```
#[stable(feature = "str_escape", since = "1.34.0")]
pub fn escape_unicode(&self) -> EscapeUnicode<'_> {
EscapeUnicode { inner: self.chars().flat_map(CharEscapeUnicode) }
}
}
impl_fn_for_zst! {
#[derive(Clone)]
struct CharEscapeDebugContinue impl Fn = |c: char| -> char::EscapeDebug {
c.escape_debug_ext(false)
};
#[derive(Clone)]
struct CharEscapeUnicode impl Fn = |c: char| -> char::EscapeUnicode {
c.escape_unicode()
};
#[derive(Clone)]
struct CharEscapeDefault impl Fn = |c: char| -> char::EscapeDefault {
c.escape_default()
};
}
#[stable(feature = "rust1", since = "1.0.0")]
impl AsRef<[u8]> for str {
#[inline]
fn as_ref(&self) -> &[u8] {
self.as_bytes()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl Default for &str {
/// Creates an empty str
fn default() -> Self { "" }
}
#[stable(feature = "default_mut_str", since = "1.28.0")]
impl Default for &mut str {
/// Creates an empty mutable str
fn default() -> Self { unsafe { from_utf8_unchecked_mut(&mut []) } }
}
/// An iterator over the non-whitespace substrings of a string,
/// separated by any amount of whitespace.
///
/// This struct is created by the [`split_whitespace`] method on [`str`].
/// See its documentation for more.
///
/// [`split_whitespace`]: ../../std/primitive.str.html#method.split_whitespace
/// [`str`]: ../../std/primitive.str.html
#[stable(feature = "split_whitespace", since = "1.1.0")]
#[derive(Clone, Debug)]
pub struct SplitWhitespace<'a> {
inner: Filter<Split<'a, IsWhitespace>, IsNotEmpty>,
}
/// An iterator over the non-ASCII-whitespace substrings of a string,
/// separated by any amount of ASCII whitespace.
///
/// This struct is created by the [`split_ascii_whitespace`] method on [`str`].
/// See its documentation for more.
///
/// [`split_ascii_whitespace`]: ../../std/primitive.str.html#method.split_ascii_whitespace
/// [`str`]: ../../std/primitive.str.html
#[stable(feature = "split_ascii_whitespace", since = "1.34.0")]
#[derive(Clone, Debug)]
pub struct SplitAsciiWhitespace<'a> {
inner: Map<Filter<SliceSplit<'a, u8, IsAsciiWhitespace>, BytesIsNotEmpty>, UnsafeBytesToStr>,
}
impl_fn_for_zst! {
#[derive(Clone)]
struct IsWhitespace impl Fn = |c: char| -> bool {
c.is_whitespace()
};
#[derive(Clone)]
struct IsAsciiWhitespace impl Fn = |byte: &u8| -> bool {
byte.is_ascii_whitespace()
};
#[derive(Clone)]
struct IsNotEmpty impl<'a, 'b> Fn = |s: &'a &'b str| -> bool {
!s.is_empty()
};
#[derive(Clone)]
struct BytesIsNotEmpty impl<'a, 'b> Fn = |s: &'a &'b [u8]| -> bool {
!s.is_empty()
};
#[derive(Clone)]
struct UnsafeBytesToStr impl<'a> Fn = |bytes: &'a [u8]| -> &'a str {
unsafe { from_utf8_unchecked(bytes) }
};
}
#[stable(feature = "split_whitespace", since = "1.1.0")]
impl<'a> Iterator for SplitWhitespace<'a> {
type Item = &'a str;
#[inline]
fn next(&mut self) -> Option<&'a str> {
self.inner.next()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
#[inline]
fn last(mut self) -> Option<&'a str> {
self.next_back()
}
}
#[stable(feature = "split_whitespace", since = "1.1.0")]
impl<'a> DoubleEndedIterator for SplitWhitespace<'a> {
#[inline]
fn next_back(&mut self) -> Option<&'a str> {
self.inner.next_back()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl FusedIterator for SplitWhitespace<'_> {}
#[stable(feature = "split_ascii_whitespace", since = "1.34.0")]
impl<'a> Iterator for SplitAsciiWhitespace<'a> {
type Item = &'a str;
#[inline]
fn next(&mut self) -> Option<&'a str> {
self.inner.next()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
#[inline]
fn last(mut self) -> Option<&'a str> {
self.next_back()
}
}
#[stable(feature = "split_ascii_whitespace", since = "1.34.0")]
impl<'a> DoubleEndedIterator for SplitAsciiWhitespace<'a> {
#[inline]
fn next_back(&mut self) -> Option<&'a str> {
self.inner.next_back()
}
}
#[stable(feature = "split_ascii_whitespace", since = "1.34.0")]
impl FusedIterator for SplitAsciiWhitespace<'_> {}
/// An iterator of [`u16`] over the string encoded as UTF-16.
///
/// [`u16`]: ../../std/primitive.u16.html
///
/// This struct is created by the [`encode_utf16`] method on [`str`].
/// See its documentation for more.
///
/// [`encode_utf16`]: ../../std/primitive.str.html#method.encode_utf16
/// [`str`]: ../../std/primitive.str.html
#[derive(Clone)]
#[stable(feature = "encode_utf16", since = "1.8.0")]
pub struct EncodeUtf16<'a> {
chars: Chars<'a>,
extra: u16,
}
#[stable(feature = "collection_debug", since = "1.17.0")]
impl fmt::Debug for EncodeUtf16<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("EncodeUtf16 { .. }")
}
}
#[stable(feature = "encode_utf16", since = "1.8.0")]
impl<'a> Iterator for EncodeUtf16<'a> {
type Item = u16;
#[inline]
fn next(&mut self) -> Option<u16> {
if self.extra != 0 {
let tmp = self.extra;
self.extra = 0;
return Some(tmp);
}
let mut buf = [0; 2];
self.chars.next().map(|ch| {
let n = ch.encode_utf16(&mut buf).len();
if n == 2 {
self.extra = buf[1];
}
buf[0]
})
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
let (low, high) = self.chars.size_hint();
// every char gets either one u16 or two u16,
// so this iterator is between 1 or 2 times as
// long as the underlying iterator.
(low, high.and_then(|n| n.checked_mul(2)))
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl FusedIterator for EncodeUtf16<'_> {}
/// The return type of [`str::escape_debug`].
///
/// [`str::escape_debug`]: ../../std/primitive.str.html#method.escape_debug
#[stable(feature = "str_escape", since = "1.34.0")]
#[derive(Clone, Debug)]
pub struct EscapeDebug<'a> {
inner: Chain<
Flatten<option::IntoIter<char::EscapeDebug>>,
FlatMap<Chars<'a>, char::EscapeDebug, CharEscapeDebugContinue>
>,
}
/// The return type of [`str::escape_default`].
///
/// [`str::escape_default`]: ../../std/primitive.str.html#method.escape_default
#[stable(feature = "str_escape", since = "1.34.0")]
#[derive(Clone, Debug)]
pub struct EscapeDefault<'a> {
inner: FlatMap<Chars<'a>, char::EscapeDefault, CharEscapeDefault>,
}
/// The return type of [`str::escape_unicode`].
///
/// [`str::escape_unicode`]: ../../std/primitive.str.html#method.escape_unicode
#[stable(feature = "str_escape", since = "1.34.0")]
#[derive(Clone, Debug)]
pub struct EscapeUnicode<'a> {
inner: FlatMap<Chars<'a>, char::EscapeUnicode, CharEscapeUnicode>,
}
macro_rules! escape_types_impls {
($( $Name: ident ),+) => {$(
#[stable(feature = "str_escape", since = "1.34.0")]
impl<'a> fmt::Display for $Name<'a> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.clone().try_for_each(|c| f.write_char(c))
}
}
#[stable(feature = "str_escape", since = "1.34.0")]
impl<'a> Iterator for $Name<'a> {
type Item = char;
#[inline]
fn next(&mut self) -> Option<char> { self.inner.next() }
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() }
#[inline]
fn try_fold<Acc, Fold, R>(&mut self, init: Acc, fold: Fold) -> R where
Self: Sized, Fold: FnMut(Acc, Self::Item) -> R, R: Try<Ok=Acc>
{
self.inner.try_fold(init, fold)
}
#[inline]
fn fold<Acc, Fold>(self, init: Acc, fold: Fold) -> Acc
where Fold: FnMut(Acc, Self::Item) -> Acc,
{
self.inner.fold(init, fold)
}
}
#[stable(feature = "str_escape", since = "1.34.0")]
impl<'a> FusedIterator for $Name<'a> {}
)+}
}
escape_types_impls!(EscapeDebug, EscapeDefault, EscapeUnicode);