972 lines
28 KiB
Rust
972 lines
28 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! A character type.
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//!
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//! The `char` type represents a single character. More specifically, since
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//! 'character' isn't a well-defined concept in Unicode, `char` is a '[Unicode
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//! scalar value]', which is similar to, but not the same as, a '[Unicode code
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//! point]'.
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//!
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//! [Unicode scalar value]: http://www.unicode.org/glossary/#unicode_scalar_value
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//! [Unicode code point]: http://www.unicode.org/glossary/#code_point
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//!
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//! This module exists for technical reasons, the primary documentation for
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//! `char` is directly on [the `char` primitive type](../primitive.char.html)
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//! itself.
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//!
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//! This module is the home of the iterator implementations for the iterators
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//! implemented on `char`, as well as some useful constants and conversion
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//! functions that convert various types to `char`.
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#![stable(feature = "rust1", since = "1.0.0")]
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use core::char::CharExt as C;
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use core::option::Option::{self, Some, None};
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use core::iter::Iterator;
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use tables::{derived_property, property, general_category, conversions};
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// stable reexports
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#[stable(feature = "rust1", since = "1.0.0")]
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pub use core::char::{MAX, from_u32, from_u32_unchecked, from_digit, EscapeUnicode, EscapeDefault};
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// unstable reexports
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#[unstable(feature = "unicode", issue = "27783")]
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pub use tables::UNICODE_VERSION;
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/// Returns an iterator that yields the lowercase equivalent of a `char`.
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///
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/// This `struct` is created by the [`to_lowercase()`] method on [`char`]. See
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/// its documentation for more.
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///
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/// [`to_lowercase()`]: primitive.char.html#method.escape_to_lowercase
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/// [`char`]: primitive.char.html
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct ToLowercase(CaseMappingIter);
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#[stable(feature = "rust1", since = "1.0.0")]
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impl Iterator for ToLowercase {
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type Item = char;
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fn next(&mut self) -> Option<char> {
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self.0.next()
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}
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}
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/// Returns an iterator that yields the uppercase equivalent of a `char`.
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///
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/// This `struct` is created by the [`to_uppercase()`] method on [`char`]. See
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/// its documentation for more.
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///
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/// [`to_uppercase()`]: primitive.char.html#method.escape_to_uppercase
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/// [`char`]: primitive.char.html
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct ToUppercase(CaseMappingIter);
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#[stable(feature = "rust1", since = "1.0.0")]
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impl Iterator for ToUppercase {
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type Item = char;
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fn next(&mut self) -> Option<char> {
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self.0.next()
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}
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}
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enum CaseMappingIter {
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Three(char, char, char),
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Two(char, char),
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One(char),
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Zero,
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}
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impl CaseMappingIter {
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fn new(chars: [char; 3]) -> CaseMappingIter {
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if chars[2] == '\0' {
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if chars[1] == '\0' {
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CaseMappingIter::One(chars[0]) // Including if chars[0] == '\0'
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} else {
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CaseMappingIter::Two(chars[0], chars[1])
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}
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} else {
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CaseMappingIter::Three(chars[0], chars[1], chars[2])
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}
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}
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}
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impl Iterator for CaseMappingIter {
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type Item = char;
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fn next(&mut self) -> Option<char> {
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match *self {
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CaseMappingIter::Three(a, b, c) => {
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*self = CaseMappingIter::Two(b, c);
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Some(a)
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}
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CaseMappingIter::Two(b, c) => {
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*self = CaseMappingIter::One(c);
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Some(b)
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}
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CaseMappingIter::One(c) => {
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*self = CaseMappingIter::Zero;
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Some(c)
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}
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CaseMappingIter::Zero => None,
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}
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}
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}
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#[lang = "char"]
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impl char {
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/// Checks if a `char` is a digit in the given radix.
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///
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/// A 'radix' here is sometimes also called a 'base'. A radix of two
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/// indicates a binary number, a radix of ten, decimal, and a radix of
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/// sixteen, hexicdecimal, to give some common values. Arbitrary
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/// radicum are supported.
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///
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/// Compared to `is_numeric()`, this function only recognizes the characters
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/// `0-9`, `a-z` and `A-Z`.
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///
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/// 'Digit' is defined to be only the following characters:
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///
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/// * `0-9`
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/// * `a-z`
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/// * `A-Z`
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///
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/// For a more comprehensive understanding of 'digit', see [`is_numeric()`][is_numeric].
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///
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/// [is_numeric]: #method.is_numeric
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///
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/// # Panics
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///
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/// Panics if given a radix larger than 36.
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///
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/// # Examples
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///
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/// Basic usage:
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///
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/// ```
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/// let d = '1';
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///
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/// assert!(d.is_digit(10));
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///
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/// let d = 'f';
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///
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/// assert!(d.is_digit(16));
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/// assert!(!d.is_digit(10));
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/// ```
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///
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/// Passing a large radix, causing a panic:
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///
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/// ```
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/// use std::thread;
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///
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/// let result = thread::spawn(|| {
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/// let d = '1';
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///
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/// // this panics
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/// d.is_digit(37);
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/// }).join();
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///
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/// assert!(result.is_err());
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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#[inline]
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pub fn is_digit(self, radix: u32) -> bool {
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C::is_digit(self, radix)
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}
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/// Converts a `char` to a digit in the given radix.
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///
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/// A 'radix' here is sometimes also called a 'base'. A radix of two
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/// indicates a binary number, a radix of ten, decimal, and a radix of
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/// sixteen, hexicdecimal, to give some common values. Arbitrary
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/// radicum are supported.
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///
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/// 'Digit' is defined to be only the following characters:
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///
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/// * `0-9`
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/// * `a-z`
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/// * `A-Z`
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///
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/// # Failure
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///
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/// Returns `None` if the `char` does not refer to a digit in the given radix.
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///
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/// # Panics
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///
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/// Panics if given a radix larger than 36.
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///
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/// # Examples
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///
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/// Basic usage:
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///
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/// ```
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/// let d = '1';
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///
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/// assert_eq!(d.to_digit(10), Some(1));
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///
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/// let d = 'f';
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///
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/// assert_eq!(d.to_digit(16), Some(15));
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/// ```
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///
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/// Passing a non-digit results in failure:
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///
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/// ```
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/// let d = 'f';
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///
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/// assert_eq!(d.to_digit(10), None);
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///
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/// let d = 'z';
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///
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/// assert_eq!(d.to_digit(16), None);
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/// ```
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///
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/// Passing a large radix, causing a panic:
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///
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/// ```
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/// use std::thread;
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///
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/// let result = thread::spawn(|| {
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/// let d = '1';
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///
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/// d.to_digit(37);
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/// }).join();
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///
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/// assert!(result.is_err());
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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#[inline]
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pub fn to_digit(self, radix: u32) -> Option<u32> {
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C::to_digit(self, radix)
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}
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/// Returns an iterator that yields the hexadecimal Unicode escape of a
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/// character, as `char`s.
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///
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/// All characters are escaped with Rust syntax of the form `\\u{NNNN}`
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/// where `NNNN` is the shortest hexadecimal representation.
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///
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/// # Examples
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///
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/// Basic usage:
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///
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/// ```
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/// for c in '❤'.escape_unicode() {
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/// print!("{}", c);
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/// }
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/// println!("");
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/// ```
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///
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/// This prints:
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///
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/// ```text
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/// \u{2764}
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/// ```
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///
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/// Collecting into a `String`:
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///
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/// ```
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/// let heart: String = '❤'.escape_unicode().collect();
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///
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/// assert_eq!(heart, r"\u{2764}");
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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#[inline]
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pub fn escape_unicode(self) -> EscapeUnicode {
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C::escape_unicode(self)
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}
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/// Returns an iterator that yields the literal escape code of a `char`.
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///
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/// The default is chosen with a bias toward producing literals that are
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/// legal in a variety of languages, including C++11 and similar C-family
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/// languages. The exact rules are:
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///
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/// * Tab is escaped as `\t`.
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/// * Carriage return is escaped as `\r`.
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/// * Line feed is escaped as `\n`.
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/// * Single quote is escaped as `\'`.
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/// * Double quote is escaped as `\"`.
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/// * Backslash is escaped as `\\`.
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/// * Any character in the 'printable ASCII' range `0x20` .. `0x7e`
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/// inclusive is not escaped.
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/// * All other characters are given hexadecimal Unicode escapes; see
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/// [`escape_unicode`][escape_unicode].
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///
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/// [escape_unicode]: #method.escape_unicode
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///
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/// # Examples
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///
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/// Basic usage:
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///
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/// ```
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/// for i in '"'.escape_default() {
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/// println!("{}", i);
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/// }
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/// ```
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///
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/// This prints:
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///
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/// ```text
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/// \
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/// "
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/// ```
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///
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/// Collecting into a `String`:
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///
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/// ```
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/// let quote: String = '"'.escape_default().collect();
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///
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/// assert_eq!(quote, "\\\"");
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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#[inline]
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pub fn escape_default(self) -> EscapeDefault {
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C::escape_default(self)
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}
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/// Returns the number of bytes this `char` would need if encoded in UTF-8.
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///
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/// That number of bytes is always between 1 and 4, inclusive.
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///
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/// # Examples
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///
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/// Basic usage:
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||
///
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/// ```
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/// let len = 'A'.len_utf8();
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/// assert_eq!(len, 1);
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///
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/// let len = 'ß'.len_utf8();
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/// assert_eq!(len, 2);
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///
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/// let len = 'ℝ'.len_utf8();
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/// assert_eq!(len, 3);
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///
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/// let len = '💣'.len_utf8();
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/// assert_eq!(len, 4);
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/// ```
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///
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/// The `&str` type guarantees that its contents are UTF-8, and so we can compare the length it
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/// would take if each code point was represented as a `char` vs in the `&str` itself:
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///
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/// ```
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/// // as chars
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/// let eastern = '東';
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/// let capitol = '京';
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///
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/// // both can be represented as three bytes
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/// assert_eq!(3, eastern.len_utf8());
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/// assert_eq!(3, capitol.len_utf8());
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///
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/// // as a &str, these two are encoded in UTF-8
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/// let tokyo = "東京";
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///
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/// let len = eastern.len_utf8() + capitol.len_utf8();
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///
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/// // we can see that they take six bytes total...
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/// assert_eq!(6, tokyo.len());
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///
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/// // ... just like the &str
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/// assert_eq!(len, tokyo.len());
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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#[inline]
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pub fn len_utf8(self) -> usize {
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C::len_utf8(self)
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}
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/// Returns the number of 16-bit code units this `char` would need if
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/// encoded in UTF-16.
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///
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/// See the documentation for [`len_utf8()`][len_utf8] for more explanation
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||
/// of this concept. This function is a mirror, but for UTF-16 instead of
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/// UTF-8.
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///
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/// # Examples
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///
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/// Basic usage:
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///
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/// ```
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/// let n = 'ß'.len_utf16();
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/// assert_eq!(n, 1);
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///
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/// let len = '💣'.len_utf16();
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/// assert_eq!(len, 2);
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/// ```
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#[stable(feature = "rust1", since = "1.0.0")]
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#[inline]
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pub fn len_utf16(self) -> usize {
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C::len_utf16(self)
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}
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||
|
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/// Encodes this character as UTF-8 into the provided byte buffer, and then
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/// returns the number of bytes written.
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///
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/// If the buffer is not large enough, nothing will be written into it and a
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/// `None` will be returned. A buffer of length four is large enough to
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/// encode any `char`.
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||
///
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||
/// # Examples
|
||
///
|
||
/// In both of these examples, 'ß' takes two bytes to encode.
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///
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||
/// ```
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/// #![feature(unicode)]
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||
///
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/// let mut b = [0; 2];
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||
///
|
||
/// let result = 'ß'.encode_utf8(&mut b);
|
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///
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/// assert_eq!(result, Some(2));
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/// ```
|
||
///
|
||
/// A buffer that's too small:
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///
|
||
/// ```
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/// #![feature(unicode)]
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///
|
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/// let mut b = [0; 1];
|
||
///
|
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/// let result = 'ß'.encode_utf8(&mut b);
|
||
///
|
||
/// assert_eq!(result, None);
|
||
/// ```
|
||
#[unstable(feature = "unicode",
|
||
reason = "pending decision about Iterator/Writer/Reader",
|
||
issue = "27784")]
|
||
#[inline]
|
||
pub fn encode_utf8(self, dst: &mut [u8]) -> Option<usize> {
|
||
C::encode_utf8(self, dst)
|
||
}
|
||
|
||
/// Encodes this character as UTF-16 into the provided `u16` buffer, and
|
||
/// then returns the number of `u16`s written.
|
||
///
|
||
/// If the buffer is not large enough, nothing will be written into it and a
|
||
/// `None` will be returned. A buffer of length 2 is large enough to encode
|
||
/// any `char`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// In both of these examples, 'ß' takes one `u16` to encode.
|
||
///
|
||
/// ```
|
||
/// #![feature(unicode)]
|
||
///
|
||
/// let mut b = [0; 1];
|
||
///
|
||
/// let result = 'ß'.encode_utf16(&mut b);
|
||
///
|
||
/// assert_eq!(result, Some(1));
|
||
/// ```
|
||
///
|
||
/// A buffer that's too small:
|
||
///
|
||
/// ```
|
||
/// #![feature(unicode)]
|
||
///
|
||
/// let mut b = [0; 0];
|
||
///
|
||
/// let result = 'ß'.encode_utf8(&mut b);
|
||
///
|
||
/// assert_eq!(result, None);
|
||
/// ```
|
||
#[unstable(feature = "unicode",
|
||
reason = "pending decision about Iterator/Writer/Reader",
|
||
issue = "27784")]
|
||
#[inline]
|
||
pub fn encode_utf16(self, dst: &mut [u16]) -> Option<usize> {
|
||
C::encode_utf16(self, dst)
|
||
}
|
||
|
||
/// Returns true if this `char` is an alphabetic code point, and false if not.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let c = 'a';
|
||
///
|
||
/// assert!(c.is_alphabetic());
|
||
///
|
||
/// let c = '京';
|
||
/// assert!(c.is_alphabetic());
|
||
///
|
||
/// let c = '💝';
|
||
/// // love is many things, but it is not alphabetic
|
||
/// assert!(!c.is_alphabetic());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn is_alphabetic(self) -> bool {
|
||
match self {
|
||
'a'...'z' | 'A'...'Z' => true,
|
||
c if c > '\x7f' => derived_property::Alphabetic(c),
|
||
_ => false,
|
||
}
|
||
}
|
||
|
||
/// Returns true if this `char` satisfies the 'XID_Start' Unicode property, and false
|
||
/// otherwise.
|
||
///
|
||
/// 'XID_Start' is a Unicode Derived Property specified in
|
||
/// [UAX #31](http://unicode.org/reports/tr31/#NFKC_Modifications),
|
||
/// mostly similar to `ID_Start` but modified for closure under `NFKx`.
|
||
#[unstable(feature = "unicode",
|
||
reason = "mainly needed for compiler internals",
|
||
issue = "0")]
|
||
#[inline]
|
||
pub fn is_xid_start(self) -> bool {
|
||
derived_property::XID_Start(self)
|
||
}
|
||
|
||
/// Returns true if this `char` satisfies the 'XID_Continue' Unicode property, and false
|
||
/// otherwise.
|
||
///
|
||
/// 'XID_Continue' is a Unicode Derived Property specified in
|
||
/// [UAX #31](http://unicode.org/reports/tr31/#NFKC_Modifications),
|
||
/// mostly similar to 'ID_Continue' but modified for closure under NFKx.
|
||
#[unstable(feature = "unicode",
|
||
reason = "mainly needed for compiler internals",
|
||
issue = "0")]
|
||
#[inline]
|
||
pub fn is_xid_continue(self) -> bool {
|
||
derived_property::XID_Continue(self)
|
||
}
|
||
|
||
/// Returns true if this `char` is lowercase, and false otherwise.
|
||
///
|
||
/// 'Lowercase' is defined according to the terms of the Unicode Derived Core
|
||
/// Property `Lowercase`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let c = 'a';
|
||
/// assert!(c.is_lowercase());
|
||
///
|
||
/// let c = 'δ';
|
||
/// assert!(c.is_lowercase());
|
||
///
|
||
/// let c = 'A';
|
||
/// assert!(!c.is_lowercase());
|
||
///
|
||
/// let c = 'Δ';
|
||
/// assert!(!c.is_lowercase());
|
||
///
|
||
/// // The various Chinese scripts do not have case, and so:
|
||
/// let c = '中';
|
||
/// assert!(!c.is_lowercase());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn is_lowercase(self) -> bool {
|
||
match self {
|
||
'a'...'z' => true,
|
||
c if c > '\x7f' => derived_property::Lowercase(c),
|
||
_ => false,
|
||
}
|
||
}
|
||
|
||
/// Returns true if this `char` is uppercase, and false otherwise.
|
||
///
|
||
/// 'Uppercase' is defined according to the terms of the Unicode Derived Core
|
||
/// Property `Uppercase`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let c = 'a';
|
||
/// assert!(!c.is_uppercase());
|
||
///
|
||
/// let c = 'δ';
|
||
/// assert!(!c.is_uppercase());
|
||
///
|
||
/// let c = 'A';
|
||
/// assert!(c.is_uppercase());
|
||
///
|
||
/// let c = 'Δ';
|
||
/// assert!(c.is_uppercase());
|
||
///
|
||
/// // The various Chinese scripts do not have case, and so:
|
||
/// let c = '中';
|
||
/// assert!(!c.is_uppercase());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn is_uppercase(self) -> bool {
|
||
match self {
|
||
'A'...'Z' => true,
|
||
c if c > '\x7f' => derived_property::Uppercase(c),
|
||
_ => false,
|
||
}
|
||
}
|
||
|
||
/// Returns true if this `char` is whitespace, and false otherwise.
|
||
///
|
||
/// 'Whitespace' is defined according to the terms of the Unicode Derived Core
|
||
/// Property `White_Space`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let c = ' ';
|
||
/// assert!(c.is_whitespace());
|
||
///
|
||
/// // a non-breaking space
|
||
/// let c = '\u{A0}';
|
||
/// assert!(c.is_whitespace());
|
||
///
|
||
/// let c = '越';
|
||
/// assert!(!c.is_whitespace());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn is_whitespace(self) -> bool {
|
||
match self {
|
||
' ' | '\x09'...'\x0d' => true,
|
||
c if c > '\x7f' => property::White_Space(c),
|
||
_ => false,
|
||
}
|
||
}
|
||
|
||
/// Returns true if this `char` is alphanumeric, and false otherwise.
|
||
///
|
||
/// 'Alphanumeric'-ness is defined in terms of the Unicode General Categories
|
||
/// 'Nd', 'Nl', 'No' and the Derived Core Property 'Alphabetic'.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let c = '٣';
|
||
/// assert!(c.is_alphanumeric());
|
||
///
|
||
/// let c = '7';
|
||
/// assert!(c.is_alphanumeric());
|
||
///
|
||
/// let c = '৬';
|
||
/// assert!(c.is_alphanumeric());
|
||
///
|
||
/// let c = 'K';
|
||
/// assert!(c.is_alphanumeric());
|
||
///
|
||
/// let c = 'و';
|
||
/// assert!(c.is_alphanumeric());
|
||
///
|
||
/// let c = '藏';
|
||
/// assert!(c.is_alphanumeric());
|
||
///
|
||
/// let c = '¾';
|
||
/// assert!(!c.is_alphanumeric());
|
||
///
|
||
/// let c = '①';
|
||
/// assert!(!c.is_alphanumeric());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn is_alphanumeric(self) -> bool {
|
||
self.is_alphabetic() || self.is_numeric()
|
||
}
|
||
|
||
/// Returns true if this `char` is a control code point, and false otherwise.
|
||
///
|
||
/// 'Control code point' is defined in terms of the Unicode General
|
||
/// Category `Cc`.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// // U+009C, STRING TERMINATOR
|
||
/// let c = '';
|
||
/// assert!(c.is_control());
|
||
///
|
||
/// let c = 'q';
|
||
/// assert!(!c.is_control());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn is_control(self) -> bool {
|
||
general_category::Cc(self)
|
||
}
|
||
|
||
/// Returns true if this `char` is numeric, and false otherwise.
|
||
///
|
||
/// 'Numeric'-ness is defined in terms of the Unicode General Categories
|
||
/// 'Nd', 'Nl', 'No'.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let c = '٣';
|
||
/// assert!(c.is_numeric());
|
||
///
|
||
/// let c = '7';
|
||
/// assert!(c.is_numeric());
|
||
///
|
||
/// let c = '৬';
|
||
/// assert!(c.is_numeric());
|
||
///
|
||
/// let c = 'K';
|
||
/// assert!(!c.is_numeric());
|
||
///
|
||
/// let c = 'و';
|
||
/// assert!(!c.is_numeric());
|
||
///
|
||
/// let c = '藏';
|
||
/// assert!(!c.is_numeric());
|
||
///
|
||
/// let c = '¾';
|
||
/// assert!(!c.is_numeric());
|
||
///
|
||
/// let c = '①';
|
||
/// assert!(!c.is_numeric());
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn is_numeric(self) -> bool {
|
||
match self {
|
||
'0'...'9' => true,
|
||
c if c > '\x7f' => general_category::N(c),
|
||
_ => false,
|
||
}
|
||
}
|
||
|
||
/// Returns an iterator that yields the lowercase equivalent of a `char`.
|
||
///
|
||
/// If no conversion is possible then an iterator with just the input character is returned.
|
||
///
|
||
/// This performs complex unconditional mappings with no tailoring: it maps
|
||
/// one Unicode character to its lowercase equivalent according to the
|
||
/// [Unicode database] and the additional complex mappings
|
||
/// [`SpecialCasing.txt`]. Conditional mappings (based on context or
|
||
/// language) are not considered here.
|
||
///
|
||
/// For a full reference, see [here][reference].
|
||
///
|
||
/// [Unicode database]: ftp://ftp.unicode.org/Public/UNIDATA/UnicodeData.txt
|
||
///
|
||
/// [`SpecialCasing.txt`]: ftp://ftp.unicode.org/Public/UNIDATA/SpecialCasing.txt
|
||
///
|
||
/// [reference]: http://www.unicode.org/versions/Unicode7.0.0/ch03.pdf#G33992
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let c = 'c';
|
||
///
|
||
/// assert_eq!(c.to_uppercase().next(), Some('C'));
|
||
///
|
||
/// // Japanese scripts do not have case, and so:
|
||
/// let c = '山';
|
||
/// assert_eq!(c.to_uppercase().next(), Some('山'));
|
||
/// ```
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn to_lowercase(self) -> ToLowercase {
|
||
ToLowercase(CaseMappingIter::new(conversions::to_lower(self)))
|
||
}
|
||
|
||
/// Returns an iterator that yields the uppercase equivalent of a `char`.
|
||
///
|
||
/// If no conversion is possible then an iterator with just the input character is returned.
|
||
///
|
||
/// This performs complex unconditional mappings with no tailoring: it maps
|
||
/// one Unicode character to its uppercase equivalent according to the
|
||
/// [Unicode database] and the additional complex mappings
|
||
/// [`SpecialCasing.txt`]. Conditional mappings (based on context or
|
||
/// language) are not considered here.
|
||
///
|
||
/// For a full reference, see [here][reference].
|
||
///
|
||
/// [Unicode database]: ftp://ftp.unicode.org/Public/UNIDATA/UnicodeData.txt
|
||
///
|
||
/// [`SpecialCasing.txt`]: ftp://ftp.unicode.org/Public/UNIDATA/SpecialCasing.txt
|
||
///
|
||
/// [reference]: http://www.unicode.org/versions/Unicode7.0.0/ch03.pdf#G33992
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// let c = 'c';
|
||
/// assert_eq!(c.to_uppercase().next(), Some('C'));
|
||
///
|
||
/// // Japanese does not have case, and so:
|
||
/// let c = '山';
|
||
/// assert_eq!(c.to_uppercase().next(), Some('山'));
|
||
/// ```
|
||
///
|
||
/// In Turkish, the equivalent of 'i' in Latin has five forms instead of two:
|
||
///
|
||
/// * 'Dotless': I / ı, sometimes written ï
|
||
/// * 'Dotted': İ / i
|
||
///
|
||
/// Note that the lowercase dotted 'i' is the same as the Latin. Therefore:
|
||
///
|
||
/// ```
|
||
/// let i = 'i';
|
||
///
|
||
/// let upper_i = i.to_uppercase().next();
|
||
/// ```
|
||
///
|
||
/// The value of `upper_i` here relies on the language of the text: if we're
|
||
/// in `en-US`, it should be `Some('I')`, but if we're in `tr_TR`, it should
|
||
/// be `Some('İ')`. `to_uppercase()` does not take this into account, and so:
|
||
///
|
||
/// ```
|
||
/// let i = 'i';
|
||
///
|
||
/// let upper_i = i.to_uppercase().next();
|
||
///
|
||
/// assert_eq!(Some('I'), upper_i);
|
||
/// ```
|
||
///
|
||
/// holds across languages.
|
||
#[stable(feature = "rust1", since = "1.0.0")]
|
||
#[inline]
|
||
pub fn to_uppercase(self) -> ToUppercase {
|
||
ToUppercase(CaseMappingIter::new(conversions::to_upper(self)))
|
||
}
|
||
}
|
||
|
||
/// An iterator that decodes UTF-16 encoded code points from an iterator of `u16`s.
|
||
#[unstable(feature = "decode_utf16", reason = "recently exposed", issue = "27830")]
|
||
#[derive(Clone)]
|
||
pub struct DecodeUtf16<I>
|
||
where I: Iterator<Item = u16>
|
||
{
|
||
iter: I,
|
||
buf: Option<u16>,
|
||
}
|
||
|
||
/// Create an iterator over the UTF-16 encoded code points in `iterable`,
|
||
/// returning unpaired surrogates as `Err`s.
|
||
///
|
||
/// # Examples
|
||
///
|
||
/// Basic usage:
|
||
///
|
||
/// ```
|
||
/// #![feature(decode_utf16)]
|
||
///
|
||
/// use std::char::decode_utf16;
|
||
///
|
||
/// fn main() {
|
||
/// // 𝄞mus<invalid>ic<invalid>
|
||
/// let v = [0xD834, 0xDD1E, 0x006d, 0x0075,
|
||
/// 0x0073, 0xDD1E, 0x0069, 0x0063,
|
||
/// 0xD834];
|
||
///
|
||
/// assert_eq!(decode_utf16(v.iter().cloned()).collect::<Vec<_>>(),
|
||
/// vec![Ok('𝄞'),
|
||
/// Ok('m'), Ok('u'), Ok('s'),
|
||
/// Err(0xDD1E),
|
||
/// Ok('i'), Ok('c'),
|
||
/// Err(0xD834)]);
|
||
/// }
|
||
/// ```
|
||
///
|
||
/// A lossy decoder can be obtained by replacing `Err` results with the replacement character:
|
||
///
|
||
/// ```
|
||
/// #![feature(decode_utf16)]
|
||
///
|
||
/// use std::char::{decode_utf16, REPLACEMENT_CHARACTER};
|
||
///
|
||
/// fn main() {
|
||
/// // 𝄞mus<invalid>ic<invalid>
|
||
/// let v = [0xD834, 0xDD1E, 0x006d, 0x0075,
|
||
/// 0x0073, 0xDD1E, 0x0069, 0x0063,
|
||
/// 0xD834];
|
||
///
|
||
/// assert_eq!(decode_utf16(v.iter().cloned())
|
||
/// .map(|r| r.unwrap_or(REPLACEMENT_CHARACTER))
|
||
/// .collect::<String>(),
|
||
/// "𝄞mus<75>ic<69>");
|
||
/// }
|
||
/// ```
|
||
#[unstable(feature = "decode_utf16", reason = "recently exposed", issue = "27830")]
|
||
#[inline]
|
||
pub fn decode_utf16<I: IntoIterator<Item = u16>>(iterable: I) -> DecodeUtf16<I::IntoIter> {
|
||
DecodeUtf16 {
|
||
iter: iterable.into_iter(),
|
||
buf: None,
|
||
}
|
||
}
|
||
|
||
#[unstable(feature = "decode_utf16", reason = "recently exposed", issue = "27830")]
|
||
impl<I: Iterator<Item=u16>> Iterator for DecodeUtf16<I> {
|
||
type Item = Result<char, u16>;
|
||
|
||
fn next(&mut self) -> Option<Result<char, u16>> {
|
||
let u = match self.buf.take() {
|
||
Some(buf) => buf,
|
||
None => match self.iter.next() {
|
||
Some(u) => u,
|
||
None => return None,
|
||
},
|
||
};
|
||
|
||
if u < 0xD800 || 0xDFFF < u {
|
||
// not a surrogate
|
||
Some(Ok(unsafe { from_u32_unchecked(u as u32) }))
|
||
} else if u >= 0xDC00 {
|
||
// a trailing surrogate
|
||
Some(Err(u))
|
||
} else {
|
||
let u2 = match self.iter.next() {
|
||
Some(u2) => u2,
|
||
// eof
|
||
None => return Some(Err(u)),
|
||
};
|
||
if u2 < 0xDC00 || u2 > 0xDFFF {
|
||
// not a trailing surrogate so we're not a valid
|
||
// surrogate pair, so rewind to redecode u2 next time.
|
||
self.buf = Some(u2);
|
||
return Some(Err(u));
|
||
}
|
||
|
||
// all ok, so lets decode it.
|
||
let c = (((u - 0xD800) as u32) << 10 | (u2 - 0xDC00) as u32) + 0x1_0000;
|
||
Some(Ok(unsafe { from_u32_unchecked(c) }))
|
||
}
|
||
}
|
||
|
||
#[inline]
|
||
fn size_hint(&self) -> (usize, Option<usize>) {
|
||
let (low, high) = self.iter.size_hint();
|
||
// we could be entirely valid surrogates (2 elements per
|
||
// char), or entirely non-surrogates (1 element per char)
|
||
(low / 2, high)
|
||
}
|
||
}
|
||
|
||
/// `U+FFFD REPLACEMENT CHARACTER` (<28>) is used in Unicode to represent a decoding error.
|
||
/// It can occur, for example, when giving ill-formed UTF-8 bytes to
|
||
/// [`String::from_utf8_lossy`](../string/struct.String.html#method.from_utf8_lossy).
|
||
#[unstable(feature = "decode_utf16", reason = "recently added", issue = "27830")]
|
||
pub const REPLACEMENT_CHARACTER: char = '\u{FFFD}';
|