394 lines
12 KiB
Rust
394 lines
12 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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//! Character manipulation.
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//!
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//! For more details, see ::rustc_unicode::char (a.k.a. std::char)
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#![allow(non_snake_case)]
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#![stable(feature = "core_char", since = "1.2.0")]
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use iter::Iterator;
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use mem::transmute;
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use option::Option::{None, Some};
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use option::Option;
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use slice::SliceExt;
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// UTF-8 ranges and tags for encoding characters
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const TAG_CONT: u8 = 0b1000_0000;
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const TAG_TWO_B: u8 = 0b1100_0000;
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const TAG_THREE_B: u8 = 0b1110_0000;
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const TAG_FOUR_B: u8 = 0b1111_0000;
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const MAX_ONE_B: u32 = 0x80;
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const MAX_TWO_B: u32 = 0x800;
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const MAX_THREE_B: u32 = 0x10000;
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/*
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Lu Uppercase_Letter an uppercase letter
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Ll Lowercase_Letter a lowercase letter
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Lt Titlecase_Letter a digraphic character, with first part uppercase
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Lm Modifier_Letter a modifier letter
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Lo Other_Letter other letters, including syllables and ideographs
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Mn Nonspacing_Mark a nonspacing combining mark (zero advance width)
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Mc Spacing_Mark a spacing combining mark (positive advance width)
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Me Enclosing_Mark an enclosing combining mark
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Nd Decimal_Number a decimal digit
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Nl Letter_Number a letterlike numeric character
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No Other_Number a numeric character of other type
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Pc Connector_Punctuation a connecting punctuation mark, like a tie
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Pd Dash_Punctuation a dash or hyphen punctuation mark
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Ps Open_Punctuation an opening punctuation mark (of a pair)
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Pe Close_Punctuation a closing punctuation mark (of a pair)
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Pi Initial_Punctuation an initial quotation mark
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Pf Final_Punctuation a final quotation mark
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Po Other_Punctuation a punctuation mark of other type
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Sm Math_Symbol a symbol of primarily mathematical use
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Sc Currency_Symbol a currency sign
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Sk Modifier_Symbol a non-letterlike modifier symbol
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So Other_Symbol a symbol of other type
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Zs Space_Separator a space character (of various non-zero widths)
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Zl Line_Separator U+2028 LINE SEPARATOR only
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Zp Paragraph_Separator U+2029 PARAGRAPH SEPARATOR only
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Cc Control a C0 or C1 control code
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Cf Format a format control character
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Cs Surrogate a surrogate code point
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Co Private_Use a private-use character
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Cn Unassigned a reserved unassigned code point or a noncharacter
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*/
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/// The highest valid code point
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#[stable(feature = "rust1", since = "1.0.0")]
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pub const MAX: char = '\u{10ffff}';
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/// Converts a `u32` to an `Option<char>`.
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///
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/// # Examples
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///
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/// ```
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/// use std::char;
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///
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/// assert_eq!(char::from_u32(0x2764), Some('❤'));
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/// assert_eq!(char::from_u32(0x110000), None); // invalid character
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/// ```
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#[inline]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn from_u32(i: u32) -> Option<char> {
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// catch out-of-bounds and surrogates
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if (i > MAX as u32) || (i >= 0xD800 && i <= 0xDFFF) {
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None
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} else {
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Some(unsafe { from_u32_unchecked(i) })
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}
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}
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/// Converts a `u32` to an `char`, not checking whether it is a valid unicode
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/// codepoint.
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#[inline]
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#[unstable(feature = "char_from_unchecked", reason = "recently added API",
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issue = "27781")]
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pub unsafe fn from_u32_unchecked(i: u32) -> char {
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transmute(i)
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}
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/// Converts a number to the character representing it.
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///
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/// # Return value
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///
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/// Returns `Some(char)` if `num` represents one digit under `radix`,
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/// using one character of `0-9` or `a-z`, or `None` if it doesn't.
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///
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/// # Panics
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///
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/// Panics if given an `radix` > 36.
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///
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/// # Examples
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///
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/// ```
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/// use std::char;
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///
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/// let c = char::from_digit(4, 10);
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///
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/// assert_eq!(c, Some('4'));
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/// ```
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#[inline]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub fn from_digit(num: u32, radix: u32) -> Option<char> {
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if radix > 36 {
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panic!("from_digit: radix is too high (maximum 36)");
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}
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if num < radix {
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let num = num as u8;
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if num < 10 {
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Some((b'0' + num) as char)
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} else {
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Some((b'a' + num - 10) as char)
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}
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} else {
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None
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}
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}
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// NB: the stabilization and documentation for this trait is in
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// unicode/char.rs, not here
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#[allow(missing_docs)] // docs in libunicode/u_char.rs
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#[doc(hidden)]
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#[unstable(feature = "core_char_ext",
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reason = "the stable interface is `impl char` in later crate",
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issue = "27701")]
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pub trait CharExt {
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fn is_digit(self, radix: u32) -> bool;
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fn to_digit(self, radix: u32) -> Option<u32>;
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fn escape_unicode(self) -> EscapeUnicode;
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fn escape_default(self) -> EscapeDefault;
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fn needs_escape_default(self) -> bool;
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fn len_utf8(self) -> usize;
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fn len_utf16(self) -> usize;
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fn encode_utf8(self, dst: &mut [u8]) -> Option<usize>;
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fn encode_utf16(self, dst: &mut [u16]) -> Option<usize>;
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}
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impl CharExt for char {
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#[inline]
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fn is_digit(self, radix: u32) -> bool {
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self.to_digit(radix).is_some()
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}
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#[inline]
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fn to_digit(self, radix: u32) -> Option<u32> {
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if radix > 36 {
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panic!("to_digit: radix is too high (maximum 36)");
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}
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let val = match self {
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'0' ... '9' => self as u32 - '0' as u32,
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'a' ... 'z' => self as u32 - 'a' as u32 + 10,
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'A' ... 'Z' => self as u32 - 'A' as u32 + 10,
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_ => return None,
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};
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if val < radix { Some(val) }
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else { None }
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}
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#[inline]
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fn escape_unicode(self) -> EscapeUnicode {
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EscapeUnicode { c: self, state: EscapeUnicodeState::Backslash }
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}
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#[inline]
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fn escape_default(self) -> EscapeDefault {
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let init_state = match self {
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'\t' => EscapeDefaultState::Backslash('t'),
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'\r' => EscapeDefaultState::Backslash('r'),
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'\n' => EscapeDefaultState::Backslash('n'),
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'\\' => EscapeDefaultState::Backslash('\\'),
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'\'' => EscapeDefaultState::Backslash('\''),
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'"' => EscapeDefaultState::Backslash('"'),
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'\x20' ... '\x7e' => EscapeDefaultState::Char(self),
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_ => EscapeDefaultState::Unicode(self.escape_unicode())
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};
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EscapeDefault { state: init_state }
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}
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#[inline]
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fn needs_escape_default(self) -> bool {
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match self {
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'\\' | '\'' | '"' => true,
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'\x20' ... '\x7e' => false,
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_ => true
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}
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}
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#[inline]
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fn len_utf8(self) -> usize {
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let code = self as u32;
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if code < MAX_ONE_B {
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1
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} else if code < MAX_TWO_B {
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2
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} else if code < MAX_THREE_B {
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3
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} else {
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4
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}
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}
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#[inline]
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fn len_utf16(self) -> usize {
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let ch = self as u32;
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if (ch & 0xFFFF) == ch { 1 } else { 2 }
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}
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#[inline]
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fn encode_utf8(self, dst: &mut [u8]) -> Option<usize> {
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encode_utf8_raw(self as u32, dst)
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}
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#[inline]
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fn encode_utf16(self, dst: &mut [u16]) -> Option<usize> {
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encode_utf16_raw(self as u32, dst)
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}
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}
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/// Encodes a raw u32 value as UTF-8 into the provided byte buffer,
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/// and then 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
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/// and a `None` will be returned.
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#[inline]
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#[unstable(feature = "char_internals",
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reason = "this function should not be exposed publicly",
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issue = "0")]
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#[doc(hidden)]
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pub fn encode_utf8_raw(code: u32, dst: &mut [u8]) -> Option<usize> {
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// Marked #[inline] to allow llvm optimizing it away
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if code < MAX_ONE_B && !dst.is_empty() {
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dst[0] = code as u8;
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Some(1)
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} else if code < MAX_TWO_B && dst.len() >= 2 {
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dst[0] = (code >> 6 & 0x1F) as u8 | TAG_TWO_B;
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dst[1] = (code & 0x3F) as u8 | TAG_CONT;
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Some(2)
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} else if code < MAX_THREE_B && dst.len() >= 3 {
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dst[0] = (code >> 12 & 0x0F) as u8 | TAG_THREE_B;
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dst[1] = (code >> 6 & 0x3F) as u8 | TAG_CONT;
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dst[2] = (code & 0x3F) as u8 | TAG_CONT;
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Some(3)
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} else if dst.len() >= 4 {
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dst[0] = (code >> 18 & 0x07) as u8 | TAG_FOUR_B;
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dst[1] = (code >> 12 & 0x3F) as u8 | TAG_CONT;
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dst[2] = (code >> 6 & 0x3F) as u8 | TAG_CONT;
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dst[3] = (code & 0x3F) as u8 | TAG_CONT;
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Some(4)
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} else {
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None
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}
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}
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/// Encodes a raw u32 value as UTF-16 into the provided `u16` buffer,
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/// and then returns the number of `u16`s written.
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///
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/// If the buffer is not large enough, nothing will be written into it
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/// and a `None` will be returned.
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#[inline]
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#[unstable(feature = "char_internals",
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reason = "this function should not be exposed publicly",
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issue = "0")]
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#[doc(hidden)]
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pub fn encode_utf16_raw(mut ch: u32, dst: &mut [u16]) -> Option<usize> {
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// Marked #[inline] to allow llvm optimizing it away
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if (ch & 0xFFFF) == ch && !dst.is_empty() {
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// The BMP falls through (assuming non-surrogate, as it should)
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dst[0] = ch as u16;
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Some(1)
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} else if dst.len() >= 2 {
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// Supplementary planes break into surrogates.
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ch -= 0x1_0000;
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dst[0] = 0xD800 | ((ch >> 10) as u16);
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dst[1] = 0xDC00 | ((ch as u16) & 0x3FF);
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Some(2)
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} else {
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None
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}
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}
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/// An iterator over the characters that represent a `char`, as escaped by
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/// Rust's unicode escaping rules.
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#[derive(Clone)]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct EscapeUnicode {
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c: char,
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state: EscapeUnicodeState
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}
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#[derive(Clone)]
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enum EscapeUnicodeState {
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Backslash,
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Type,
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LeftBrace,
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Value(usize),
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RightBrace,
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Done,
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl Iterator for EscapeUnicode {
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type Item = char;
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fn next(&mut self) -> Option<char> {
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match self.state {
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EscapeUnicodeState::Backslash => {
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self.state = EscapeUnicodeState::Type;
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Some('\\')
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}
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EscapeUnicodeState::Type => {
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self.state = EscapeUnicodeState::LeftBrace;
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Some('u')
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}
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EscapeUnicodeState::LeftBrace => {
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let mut n = 0;
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while (self.c as u32) >> (4 * (n + 1)) != 0 {
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n += 1;
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}
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self.state = EscapeUnicodeState::Value(n);
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Some('{')
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}
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EscapeUnicodeState::Value(offset) => {
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let c = from_digit(((self.c as u32) >> (offset * 4)) & 0xf, 16).unwrap();
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if offset == 0 {
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self.state = EscapeUnicodeState::RightBrace;
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} else {
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self.state = EscapeUnicodeState::Value(offset - 1);
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}
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Some(c)
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}
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EscapeUnicodeState::RightBrace => {
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self.state = EscapeUnicodeState::Done;
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Some('}')
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}
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EscapeUnicodeState::Done => None,
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}
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}
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}
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/// An iterator over the characters that represent a `char`, escaped
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/// for maximum portability.
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#[derive(Clone)]
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#[stable(feature = "rust1", since = "1.0.0")]
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pub struct EscapeDefault {
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state: EscapeDefaultState
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}
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#[derive(Clone)]
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enum EscapeDefaultState {
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Backslash(char),
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Char(char),
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Done,
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Unicode(EscapeUnicode),
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}
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#[stable(feature = "rust1", since = "1.0.0")]
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impl Iterator for EscapeDefault {
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type Item = char;
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fn next(&mut self) -> Option<char> {
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match self.state {
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EscapeDefaultState::Backslash(c) => {
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self.state = EscapeDefaultState::Char(c);
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Some('\\')
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}
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EscapeDefaultState::Char(c) => {
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self.state = EscapeDefaultState::Done;
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Some(c)
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}
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EscapeDefaultState::Done => None,
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EscapeDefaultState::Unicode(ref mut iter) => iter.next()
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}
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}
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}
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