sgx_trts/src/ascii.rs - incubator-teaclave-sgx-sdk - Git at Google

 // Copyright (c) 2017 Baidu, Inc. All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions
 // are met:
 //
 //  * Redistributions of source code must retain the above copyright
 //    notice, this list of conditions and the following disclaimer.
 //  * Redistributions in binary form must reproduce the above copyright
 //    notice, this list of conditions and the following disclaimer in
 //    the documentation and/or other materials provided with the
 //    distribution.
 //  * Neither the name of Baidu, Inc., nor the names of its
 //    contributors may be used to endorse or promote products derived
 //    from this software without specific prior written permission.
 //
 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 use core::ops::Range;
 use core::iter::FusedIterator;
 use core::str;
 use core::fmt;
 use alloc::vec::Vec;
 use alloc::string::String;

 pub trait AsciiExt {
     /// Container type for copied ASCII characters.
     type Owned;

     /// Checks if the value is within the ASCII range.
     ///
     fn is_ascii(&self) -> bool;
     /// Makes a copy of the value in its ASCII upper case equivalent.
     ///
     /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
     /// but non-ASCII letters are unchanged.
     ///
     /// To uppercase the value in-place, use [`make_ascii_uppercase`].
     ///
     /// To uppercase ASCII characters in addition to non-ASCII characters, use
     /// [`str::to_uppercase`].
     ///
     fn to_ascii_uppercase(&self) -> Self::Owned;

     /// Makes a copy of the value in its ASCII lower case equivalent.
     ///
     /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
     /// but non-ASCII letters are unchanged.
     ///
     /// To lowercase the value in-place, use [`make_ascii_lowercase`].
     ///
     /// To lowercase ASCII characters in addition to non-ASCII characters, use
     /// [`str::to_lowercase`].
     ///
     fn to_ascii_lowercase(&self) -> Self::Owned;

     /// Checks that two values are an ASCII case-insensitive match.
     ///
     /// Same as `to_ascii_lowercase(a) == to_ascii_lowercase(b)`,
     /// but without allocating and copying temporaries.
     ///
     fn eq_ignore_ascii_case(&self, other: &Self) -> bool;

     /// Converts this type 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`].
     ///
     fn make_ascii_uppercase(&mut self);

     /// Converts this type 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`].
     ///
     fn make_ascii_lowercase(&mut self);

     /// Checks if the value is an ASCII alphabetic character:
     /// U+0041 'A' ... U+005A 'Z' or U+0061 'a' ... U+007A 'z'.
     /// For strings, true if all characters in the string are
     /// ASCII alphabetic.
     ///
     fn is_ascii_alphabetic(&self) -> bool { unimplemented!(); }

     /// Checks if the value is an ASCII uppercase character:
     /// U+0041 'A' ... U+005A 'Z'.
     /// For strings, true if all characters in the string are
     /// ASCII uppercase.
     ///
     fn is_ascii_uppercase(&self) -> bool { unimplemented!(); }

     /// Checks if the value is an ASCII lowercase character:
     /// U+0061 'a' ... U+007A 'z'.
     /// For strings, true if all characters in the string are
     /// ASCII lowercase.
     ///
     fn is_ascii_lowercase(&self) -> bool { unimplemented!(); }

     /// Checks if the value is an ASCII alphanumeric character:
     /// U+0041 'A' ... U+005A 'Z', U+0061 'a' ... U+007A 'z', or
     /// U+0030 '0' ... U+0039 '9'.
     /// For strings, true if all characters in the string are
     /// ASCII alphanumeric.
     ///
     fn is_ascii_alphanumeric(&self) -> bool { unimplemented!(); }

     /// Checks if the value is an ASCII decimal digit:
     /// U+0030 '0' ... U+0039 '9'.
     /// For strings, true if all characters in the string are
     /// ASCII digits.
     ///
     fn is_ascii_digit(&self) -> bool { unimplemented!(); }

     /// Checks if the value is an ASCII hexadecimal digit:
     /// U+0030 '0' ... U+0039 '9', U+0041 'A' ... U+0046 'F', or
     /// U+0061 'a' ... U+0066 'f'.
     /// For strings, true if all characters in the string are
     /// ASCII hex digits.
     ///
     fn is_ascii_hexdigit(&self) -> bool { unimplemented!(); }

     /// Checks if the value is an ASCII punctuation character:
     /// U+0021 ... U+002F `! " # $ % & ' ( ) * + , - . /`
     /// U+003A ... U+0040 `: ; < = > ? @`
     /// U+005B ... U+0060 `[ \\ ] ^ _ \``
     /// U+007B ... U+007E `{ | } ~`
     /// For strings, true if all characters in the string are
     /// ASCII punctuation.
     ///
     fn is_ascii_punctuation(&self) -> bool { unimplemented!(); }

     /// Checks if the value is an ASCII graphic character:
     /// U+0021 '@' ... U+007E '~'.
     /// For strings, true if all characters in the string are
     /// ASCII punctuation.
     ///
     fn is_ascii_graphic(&self) -> bool { unimplemented!(); }

     /// Checks if the value is an ASCII whitespace character:
     /// U+0020 SPACE, U+0009 HORIZONTAL TAB, U+000A LINE FEED,
     /// U+000C FORM FEED, or U+000D CARRIAGE RETURN.
     /// For strings, true if all characters in the string are
     /// ASCII whitespace.
     ///
     /// Rust uses the WhatWG Infra Standard's [definition of ASCII
     /// whitespace][infra-aw].  There are several other definitions in
     /// wide use.  For instance, [the POSIX locale][pct] includes
     /// U+000B VERTICAL TAB as well as all the above characters,
     /// but—from the very same specification—[the default rule for
     /// "field splitting" in the Bourne shell][bfs] considers *only*
     /// SPACE, HORIZONTAL TAB, and LINE FEED as whitespace.
     ///
     /// If you are writing a program that will process an existing
     /// file format, check what that format's definition of whitespace is
     /// before using this function.
     fn is_ascii_whitespace(&self) -> bool { unimplemented!(); }

     /// Checks if the value is an ASCII control character:
     /// U+0000 NUL ... U+001F UNIT SEPARATOR, or U+007F DELETE.
     /// Note that most ASCII whitespace characters are control
     /// characters, but SPACE is not.
     ///
     fn is_ascii_control(&self) -> bool { unimplemented!(); }
 }

 impl AsciiExt for str {
     type Owned = String;

     #[inline]
     fn is_ascii(&self) -> bool {
         self.bytes().all(|b| b.is_ascii())
     }

     #[inline]
     fn to_ascii_uppercase(&self) -> String {
         let mut bytes = self.as_bytes().to_vec();
         bytes.make_ascii_uppercase();
         // make_ascii_uppercase() preserves the UTF-8 invariant.
         unsafe { String::from_utf8_unchecked(bytes) }
     }

     #[inline]
     fn to_ascii_lowercase(&self) -> String {
         let mut bytes = self.as_bytes().to_vec();
         bytes.make_ascii_lowercase();
         // make_ascii_uppercase() preserves the UTF-8 invariant.
         unsafe { String::from_utf8_unchecked(bytes) }
     }

     #[inline]
     fn eq_ignore_ascii_case(&self, other: &str) -> bool {
         self.as_bytes().eq_ignore_ascii_case(other.as_bytes())
     }

     fn make_ascii_uppercase(&mut self) {
         let me = unsafe { self.as_bytes_mut() };
         me.make_ascii_uppercase()
     }

     fn make_ascii_lowercase(&mut self) {
         let me = unsafe { self.as_bytes_mut() };
         me.make_ascii_lowercase()
     }

     #[inline]
     fn is_ascii_alphabetic(&self) -> bool {
         self.bytes().all(|b| b.is_ascii_alphabetic())
     }

     #[inline]
     fn is_ascii_uppercase(&self) -> bool {
         self.bytes().all(|b| b.is_ascii_uppercase())
     }

     #[inline]
     fn is_ascii_lowercase(&self) -> bool {
         self.bytes().all(|b| b.is_ascii_lowercase())
     }

     #[inline]
     fn is_ascii_alphanumeric(&self) -> bool {
         self.bytes().all(|b| b.is_ascii_alphanumeric())
     }

     #[inline]
     fn is_ascii_digit(&self) -> bool {
         self.bytes().all(|b| b.is_ascii_digit())
     }

     #[inline]
     fn is_ascii_hexdigit(&self) -> bool {
         self.bytes().all(|b| b.is_ascii_hexdigit())
     }

     #[inline]
     fn is_ascii_punctuation(&self) -> bool {
         self.bytes().all(|b| b.is_ascii_punctuation())
     }

     #[inline]
     fn is_ascii_graphic(&self) -> bool {
         self.bytes().all(|b| b.is_ascii_graphic())
     }

     #[inline]
     fn is_ascii_whitespace(&self) -> bool {
         self.bytes().all(|b| b.is_ascii_whitespace())
     }

     #[inline]
     fn is_ascii_control(&self) -> bool {
         self.bytes().all(|b| b.is_ascii_control())
     }
 }

 impl AsciiExt for [u8] {
     type Owned = Vec<u8>;
     #[inline]
     fn is_ascii(&self) -> bool {
         self.iter().all(|b| b.is_ascii())
     }

     #[inline]
     fn to_ascii_uppercase(&self) -> Vec<u8> {
         let mut me = self.to_vec();
         me.make_ascii_uppercase();
         return me
     }

     #[inline]
     fn to_ascii_lowercase(&self) -> Vec<u8> {
         let mut me = self.to_vec();
         me.make_ascii_lowercase();
         return me
     }

     #[inline]
     fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool {
         self.len() == other.len() &&
         self.iter().zip(other).all(|(a, b)| {
             a.eq_ignore_ascii_case(b)
         })
     }

     fn make_ascii_uppercase(&mut self) {
         for byte in self {
             byte.make_ascii_uppercase();
         }
     }

     fn make_ascii_lowercase(&mut self) {
         for byte in self {
             byte.make_ascii_lowercase();
         }
     }

     #[inline]
     fn is_ascii_alphabetic(&self) -> bool {
         self.iter().all(|b| b.is_ascii_alphabetic())
     }

     #[inline]
     fn is_ascii_uppercase(&self) -> bool {
         self.iter().all(|b| b.is_ascii_uppercase())
     }

     #[inline]
     fn is_ascii_lowercase(&self) -> bool {
         self.iter().all(|b| b.is_ascii_lowercase())
     }

     #[inline]
     fn is_ascii_alphanumeric(&self) -> bool {
         self.iter().all(|b| b.is_ascii_alphanumeric())
     }

     #[inline]
     fn is_ascii_digit(&self) -> bool {
         self.iter().all(|b| b.is_ascii_digit())
     }

     #[inline]
     fn is_ascii_hexdigit(&self) -> bool {
         self.iter().all(|b| b.is_ascii_hexdigit())
     }

     #[inline]
     fn is_ascii_punctuation(&self) -> bool {
         self.iter().all(|b| b.is_ascii_punctuation())
     }

     #[inline]
     fn is_ascii_graphic(&self) -> bool {
         self.iter().all(|b| b.is_ascii_graphic())
     }

     #[inline]
     fn is_ascii_whitespace(&self) -> bool {
         self.iter().all(|b| b.is_ascii_whitespace())
     }

     #[inline]
     fn is_ascii_control(&self) -> bool {
         self.iter().all(|b| b.is_ascii_control())
     }
 }

 impl AsciiExt for u8 {
     type Owned = u8;
     #[inline]
     fn is_ascii(&self) -> bool { *self & 128 == 0 }
     #[inline]
     fn to_ascii_uppercase(&self) -> u8 { ASCII_UPPERCASE_MAP[*self as usize] }
     #[inline]
     fn to_ascii_lowercase(&self) -> u8 { ASCII_LOWERCASE_MAP[*self as usize] }
     #[inline]
     fn eq_ignore_ascii_case(&self, other: &u8) -> bool {
         self.to_ascii_lowercase() == other.to_ascii_lowercase()
     }
     #[inline]
     fn make_ascii_uppercase(&mut self) { *self = self.to_ascii_uppercase(); }
     #[inline]
     fn make_ascii_lowercase(&mut self) { *self = self.to_ascii_lowercase(); }

     #[inline]
     fn is_ascii_alphabetic(&self) -> bool {
         if *self >= 0x80 { return false; }
         match ASCII_CHARACTER_CLASS[*self as usize] {
             L|Lx|U|Ux => true,
             _ => false
         }
     }

     #[inline]
     fn is_ascii_uppercase(&self) -> bool {
         if *self >= 0x80 { return false }
         match ASCII_CHARACTER_CLASS[*self as usize] {
             U|Ux => true,
             _ => false
         }
     }

     #[inline]
     fn is_ascii_lowercase(&self) -> bool {
         if *self >= 0x80 { return false }
         match ASCII_CHARACTER_CLASS[*self as usize] {
             L|Lx => true,
             _ => false
         }
     }

     #[inline]
     fn is_ascii_alphanumeric(&self) -> bool {
         if *self >= 0x80 { return false }
         match ASCII_CHARACTER_CLASS[*self as usize] {
             D|L|Lx|U|Ux => true,
             _ => false
         }
     }

     #[inline]
     fn is_ascii_digit(&self) -> bool {
         if *self >= 0x80 { return false }
         match ASCII_CHARACTER_CLASS[*self as usize] {
             D => true,
             _ => false
         }
     }

     #[inline]
     fn is_ascii_hexdigit(&self) -> bool {
         if *self >= 0x80 { return false }
         match ASCII_CHARACTER_CLASS[*self as usize] {
             D|Lx|Ux => true,
             _ => false
         }
     }

     #[inline]
     fn is_ascii_punctuation(&self) -> bool {
         if *self >= 0x80 { return false }
         match ASCII_CHARACTER_CLASS[*self as usize] {
             P => true,
             _ => false
         }
     }

     #[inline]
     fn is_ascii_graphic(&self) -> bool {
         if *self >= 0x80 { return false; }
         match ASCII_CHARACTER_CLASS[*self as usize] {
             Ux|U|Lx|L|D|P => true,
             _ => false
         }
     }

     #[inline]
     fn is_ascii_whitespace(&self) -> bool {
         if *self >= 0x80 { return false; }
         match ASCII_CHARACTER_CLASS[*self as usize] {
             Cw|W => true,
             _ => false
         }
     }

     #[inline]
     fn is_ascii_control(&self) -> bool {
         if *self >= 0x80 { return false; }
         match ASCII_CHARACTER_CLASS[*self as usize] {
             C|Cw => true,
             _ => false
         }
     }
 }

 impl AsciiExt for char {
     type Owned = char;
     #[inline]
     fn is_ascii(&self) -> bool {
         *self as u32 <= 0x7F
     }

     #[inline]
     fn to_ascii_uppercase(&self) -> char {
         if self.is_ascii() {
             (*self as u8).to_ascii_uppercase() as char
         } else {
             *self
         }
     }

     #[inline]
     fn to_ascii_lowercase(&self) -> char {
         if self.is_ascii() {
             (*self as u8).to_ascii_lowercase() as char
         } else {
             *self
         }
     }

     #[inline]
     fn eq_ignore_ascii_case(&self, other: &char) -> bool {
         self.to_ascii_lowercase() == other.to_ascii_lowercase()
     }

     #[inline]
     fn make_ascii_uppercase(&mut self) { *self = self.to_ascii_uppercase(); }
     #[inline]
     fn make_ascii_lowercase(&mut self) { *self = self.to_ascii_lowercase(); }

     #[inline]
     fn is_ascii_alphabetic(&self) -> bool {
         (*self as u32 <= 0x7f) && (*self as u8).is_ascii_alphabetic()
     }

     #[inline]
     fn is_ascii_uppercase(&self) -> bool {
         (*self as u32 <= 0x7f) && (*self as u8).is_ascii_uppercase()
     }

     #[inline]
     fn is_ascii_lowercase(&self) -> bool {
         (*self as u32 <= 0x7f) && (*self as u8).is_ascii_lowercase()
     }

     #[inline]
     fn is_ascii_alphanumeric(&self) -> bool {
         (*self as u32 <= 0x7f) && (*self as u8).is_ascii_alphanumeric()
     }

     #[inline]
     fn is_ascii_digit(&self) -> bool {
         (*self as u32 <= 0x7f) && (*self as u8).is_ascii_digit()
     }

     #[inline]
     fn is_ascii_hexdigit(&self) -> bool {
         (*self as u32 <= 0x7f) && (*self as u8).is_ascii_hexdigit()
     }

     #[inline]
     fn is_ascii_punctuation(&self) -> bool {
         (*self as u32 <= 0x7f) && (*self as u8).is_ascii_punctuation()
     }

     #[inline]
     fn is_ascii_graphic(&self) -> bool {
         (*self as u32 <= 0x7f) && (*self as u8).is_ascii_graphic()
     }

     #[inline]
     fn is_ascii_whitespace(&self) -> bool {
         (*self as u32 <= 0x7f) && (*self as u8).is_ascii_whitespace()
     }

     #[inline]
     fn is_ascii_control(&self) -> bool {
         (*self as u32 <= 0x7f) && (*self as u8).is_ascii_control()
     }
 }

 /// An iterator over the escaped version of a byte.
 ///
 /// This `struct` is created by the [`escape_default`] function. See its
 /// documentation for more.
 ///
 pub struct EscapeDefault {
     range: Range<usize>,
     data: [u8; 4],
 }

 /// Returns an iterator that produces an escaped version of a `u8`.
 ///
 /// The default is chosen with a bias toward producing literals that are
 /// legal in a variety of languages, including C++11 and similar C-family
 /// languages. The exact rules are:
 ///
 /// - Tab, CR and LF are escaped as '\t', '\r' and '\n' respectively.
 /// - Single-quote, double-quote and backslash chars are backslash-escaped.
 /// - Any other chars in the range [0x20,0x7e] are not escaped.
 /// - Any other chars are given hex escapes of the form '\xNN'.
 /// - Unicode escapes are never generated by this function.
 ///
 pub fn escape_default(c: u8) -> EscapeDefault {
     let (data, len) = match c {
         b'\t' => ([b'\\', b't', 0, 0], 2),
         b'\r' => ([b'\\', b'r', 0, 0], 2),
         b'\n' => ([b'\\', b'n', 0, 0], 2),
         b'\\' => ([b'\\', b'\\', 0, 0], 2),
         b'\'' => ([b'\\', b'\'', 0, 0], 2),
         b'"' => ([b'\\', b'"', 0, 0], 2),
         b'\x20' ... b'\x7e' => ([c, 0, 0, 0], 1),
         _ => ([b'\\', b'x', hexify(c >> 4), hexify(c & 0xf)], 4),
     };

     return EscapeDefault { range: (0.. len), data: data };

     fn hexify(b: u8) -> u8 {
         match b {
             0 ... 9 => b'0' + b,
             _ => b'a' + b - 10,
         }
     }
 }

 impl Iterator for EscapeDefault {
     type Item = u8;
     fn next(&mut self) -> Option<u8> { self.range.next().map(|i| self.data[i]) }
     fn size_hint(&self) -> (usize, Option<usize>) { self.range.size_hint() }
 }

 impl DoubleEndedIterator for EscapeDefault {
     fn next_back(&mut self) -> Option<u8> {
         self.range.next_back().map(|i| self.data[i])
     }
 }

 impl ExactSizeIterator for EscapeDefault {}

 impl FusedIterator for EscapeDefault {}

 impl fmt::Debug for EscapeDefault {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.pad("EscapeDefault { .. }")
     }
 }

 static ASCII_LOWERCASE_MAP: [u8; 256] = [
     0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
     0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
     0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
     0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
     b' ', b'!', b'"', b'#', b'$', b'%', b'&', b'\'',
     b'(', b')', b'*', b'+', b',', b'-', b'.', b'/',
     b'0', b'1', b'2', b'3', b'4', b'5', b'6', b'7',
     b'8', b'9', b':', b';', b'<', b'=', b'>', b'?',
     b'@',

           b'a', b'b', b'c', b'd', b'e', b'f', b'g',
     b'h', b'i', b'j', b'k', b'l', b'm', b'n', b'o',
     b'p', b'q', b'r', b's', b't', b'u', b'v', b'w',
     b'x', b'y', b'z',

                       b'[', b'\\', b']', b'^', b'_',
     b'`', b'a', b'b', b'c', b'd', b'e', b'f', b'g',
     b'h', b'i', b'j', b'k', b'l', b'm', b'n', b'o',
     b'p', b'q', b'r', b's', b't', b'u', b'v', b'w',
     b'x', b'y', b'z', b'{', b'|', b'}', b'~', 0x7f,
     0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
     0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
     0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
     0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
     0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
     0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
     0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
     0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
     0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
     0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
     0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
     0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
     0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
     0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
     0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
     0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff,
 ];

 static ASCII_UPPERCASE_MAP: [u8; 256] = [
     0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
     0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
     0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
     0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
     b' ', b'!', b'"', b'#', b'$', b'%', b'&', b'\'',
     b'(', b')', b'*', b'+', b',', b'-', b'.', b'/',
     b'0', b'1', b'2', b'3', b'4', b'5', b'6', b'7',
     b'8', b'9', b':', b';', b'<', b'=', b'>', b'?',
     b'@', b'A', b'B', b'C', b'D', b'E', b'F', b'G',
     b'H', b'I', b'J', b'K', b'L', b'M', b'N', b'O',
     b'P', b'Q', b'R', b'S', b'T', b'U', b'V', b'W',
     b'X', b'Y', b'Z', b'[', b'\\', b']', b'^', b'_',
     b'`',

           b'A', b'B', b'C', b'D', b'E', b'F', b'G',
     b'H', b'I', b'J', b'K', b'L', b'M', b'N', b'O',
     b'P', b'Q', b'R', b'S', b'T', b'U', b'V', b'W',
     b'X', b'Y', b'Z',

                       b'{', b'|', b'}', b'~', 0x7f,
     0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
     0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
     0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
     0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
     0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
     0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
     0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
     0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
     0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
     0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
     0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
     0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
     0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
     0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
     0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
     0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff,
 ];

 enum AsciiCharacterClass {
     C,  // control
     Cw, // control whitespace
     W,  // whitespace
     D,  // digit
     L,  // lowercase
     Lx, // lowercase hex digit
     U,  // uppercase
     Ux, // uppercase hex digit
     P,  // punctuation
 }
 use self::AsciiCharacterClass::*;

 static ASCII_CHARACTER_CLASS: [AsciiCharacterClass; 128] = [
 //  _0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _a _b _c _d _e _f
     C, C, C, C, C, C, C, C, C, Cw,Cw,C, Cw,Cw,C, C, // 0_
     C, C, C, C, C, C, C, C, C, C, C, C, C, C, C, C, // 1_
     W, P, P, P, P, P, P, P, P, P, P, P, P, P, P, P, // 2_
     D, D, D, D, D, D, D, D, D, D, P, P, P, P, P, P, // 3_
     P, Ux,Ux,Ux,Ux,Ux,Ux,U, U, U, U, U, U, U, U, U, // 4_
     U, U, U, U, U, U, U, U, U, U, U, P, P, P, P, P, // 5_
     P, Lx,Lx,Lx,Lx,Lx,Lx,L, L, L, L, L, L, L, L, L, // 6_
     L, L, L, L, L, L, L, L, L, L, L, P, P, P, P, C, // 7_
 ];
	// Copyright (c) 2017 Baidu, Inc. All Rights Reserved.
	//
	// Redistribution and use in source and binary forms, with or without
	// modification, are permitted provided that the following conditions
	// are met:
	//
	// * Redistributions of source code must retain the above copyright
	// notice, this list of conditions and the following disclaimer.
	// * Redistributions in binary form must reproduce the above copyright
	// notice, this list of conditions and the following disclaimer in
	// the documentation and/or other materials provided with the
	// distribution.
	// * Neither the name of Baidu, Inc., nor the names of its
	// contributors may be used to endorse or promote products derived
	// from this software without specific prior written permission.
	//
	// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

	use core::ops::Range;
	use core::iter::FusedIterator;
	use core::str;
	use core::fmt;
	use alloc::vec::Vec;
	use alloc::string::String;

	pub trait AsciiExt {
	/// Container type for copied ASCII characters.
	type Owned;

	/// Checks if the value is within the ASCII range.
	///
	fn is_ascii(&self) -> bool;
	/// Makes a copy of the value in its ASCII upper case equivalent.
	///
	/// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
	/// but non-ASCII letters are unchanged.
	///
	/// To uppercase the value in-place, use [`make_ascii_uppercase`].
	///
	/// To uppercase ASCII characters in addition to non-ASCII characters, use
	/// [`str::to_uppercase`].
	///
	fn to_ascii_uppercase(&self) -> Self::Owned;

	/// Makes a copy of the value in its ASCII lower case equivalent.
	///
	/// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
	/// but non-ASCII letters are unchanged.
	///
	/// To lowercase the value in-place, use [`make_ascii_lowercase`].
	///
	/// To lowercase ASCII characters in addition to non-ASCII characters, use
	/// [`str::to_lowercase`].
	///
	fn to_ascii_lowercase(&self) -> Self::Owned;

	/// Checks that two values are an ASCII case-insensitive match.
	///
	/// Same as `to_ascii_lowercase(a) == to_ascii_lowercase(b)`,
	/// but without allocating and copying temporaries.
	///
	fn eq_ignore_ascii_case(&self, other: &Self) -> bool;

	/// Converts this type 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`].
	///
	fn make_ascii_uppercase(&mut self);

	/// Converts this type 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`].
	///
	fn make_ascii_lowercase(&mut self);

	/// Checks if the value is an ASCII alphabetic character:
	/// U+0041 'A' ... U+005A 'Z' or U+0061 'a' ... U+007A 'z'.
	/// For strings, true if all characters in the string are
	/// ASCII alphabetic.
	///
	fn is_ascii_alphabetic(&self) -> bool { unimplemented!(); }

	/// Checks if the value is an ASCII uppercase character:
	/// U+0041 'A' ... U+005A 'Z'.
	/// For strings, true if all characters in the string are
	/// ASCII uppercase.
	///
	fn is_ascii_uppercase(&self) -> bool { unimplemented!(); }

	/// Checks if the value is an ASCII lowercase character:
	/// U+0061 'a' ... U+007A 'z'.
	/// For strings, true if all characters in the string are
	/// ASCII lowercase.
	///
	fn is_ascii_lowercase(&self) -> bool { unimplemented!(); }

	/// Checks if the value is an ASCII alphanumeric character:
	/// U+0041 'A' ... U+005A 'Z', U+0061 'a' ... U+007A 'z', or
	/// U+0030 '0' ... U+0039 '9'.
	/// For strings, true if all characters in the string are
	/// ASCII alphanumeric.
	///
	fn is_ascii_alphanumeric(&self) -> bool { unimplemented!(); }

	/// Checks if the value is an ASCII decimal digit:
	/// U+0030 '0' ... U+0039 '9'.
	/// For strings, true if all characters in the string are
	/// ASCII digits.
	///
	fn is_ascii_digit(&self) -> bool { unimplemented!(); }

	/// Checks if the value is an ASCII hexadecimal digit:
	/// U+0030 '0' ... U+0039 '9', U+0041 'A' ... U+0046 'F', or
	/// U+0061 'a' ... U+0066 'f'.
	/// For strings, true if all characters in the string are
	/// ASCII hex digits.
	///
	fn is_ascii_hexdigit(&self) -> bool { unimplemented!(); }

	/// Checks if the value is an ASCII punctuation character:
	/// U+0021 ... U+002F `! " # $ % & ' ( ) * + , - . /`
	/// U+003A ... U+0040 `: ; < = > ? @`
	/// U+005B ... U+0060 `[ \\ ] ^ _ \``
	/// U+007B ... U+007E `{ \| } ~`
	/// For strings, true if all characters in the string are
	/// ASCII punctuation.
	///
	fn is_ascii_punctuation(&self) -> bool { unimplemented!(); }

	/// Checks if the value is an ASCII graphic character:
	/// U+0021 '@' ... U+007E '~'.
	/// For strings, true if all characters in the string are
	/// ASCII punctuation.
	///
	fn is_ascii_graphic(&self) -> bool { unimplemented!(); }

	/// Checks if the value is an ASCII whitespace character:
	/// U+0020 SPACE, U+0009 HORIZONTAL TAB, U+000A LINE FEED,
	/// U+000C FORM FEED, or U+000D CARRIAGE RETURN.
	/// For strings, true if all characters in the string are
	/// ASCII whitespace.
	///
	/// Rust uses the WhatWG Infra Standard's [definition of ASCII
	/// whitespace][infra-aw]. There are several other definitions in
	/// wide use. For instance, [the POSIX locale][pct] includes
	/// U+000B VERTICAL TAB as well as all the above characters,
	/// but—from the very same specification—[the default rule for
	/// "field splitting" in the Bourne shell][bfs] considers only
	/// SPACE, HORIZONTAL TAB, and LINE FEED as whitespace.
	///
	/// If you are writing a program that will process an existing
	/// file format, check what that format's definition of whitespace is
	/// before using this function.
	fn is_ascii_whitespace(&self) -> bool { unimplemented!(); }

	/// Checks if the value is an ASCII control character:
	/// U+0000 NUL ... U+001F UNIT SEPARATOR, or U+007F DELETE.
	/// Note that most ASCII whitespace characters are control
	/// characters, but SPACE is not.
	///
	fn is_ascii_control(&self) -> bool { unimplemented!(); }
	}

	impl AsciiExt for str {
	type Owned = String;

	#[inline]
	fn is_ascii(&self) -> bool {
	self.bytes().all(\|b\| b.is_ascii())
	}

	#[inline]
	fn to_ascii_uppercase(&self) -> String {
	let mut bytes = self.as_bytes().to_vec();
	bytes.make_ascii_uppercase();
	// make_ascii_uppercase() preserves the UTF-8 invariant.
	unsafe { String::from_utf8_unchecked(bytes) }
	}

	#[inline]
	fn to_ascii_lowercase(&self) -> String {
	let mut bytes = self.as_bytes().to_vec();
	bytes.make_ascii_lowercase();
	// make_ascii_uppercase() preserves the UTF-8 invariant.
	unsafe { String::from_utf8_unchecked(bytes) }
	}

	#[inline]
	fn eq_ignore_ascii_case(&self, other: &str) -> bool {
	self.as_bytes().eq_ignore_ascii_case(other.as_bytes())
	}

	fn make_ascii_uppercase(&mut self) {
	let me = unsafe { self.as_bytes_mut() };
	me.make_ascii_uppercase()
	}

	fn make_ascii_lowercase(&mut self) {
	let me = unsafe { self.as_bytes_mut() };
	me.make_ascii_lowercase()
	}

	#[inline]
	fn is_ascii_alphabetic(&self) -> bool {
	self.bytes().all(\|b\| b.is_ascii_alphabetic())
	}

	#[inline]
	fn is_ascii_uppercase(&self) -> bool {
	self.bytes().all(\|b\| b.is_ascii_uppercase())
	}

	#[inline]
	fn is_ascii_lowercase(&self) -> bool {
	self.bytes().all(\|b\| b.is_ascii_lowercase())
	}

	#[inline]
	fn is_ascii_alphanumeric(&self) -> bool {
	self.bytes().all(\|b\| b.is_ascii_alphanumeric())
	}

	#[inline]
	fn is_ascii_digit(&self) -> bool {
	self.bytes().all(\|b\| b.is_ascii_digit())
	}

	#[inline]
	fn is_ascii_hexdigit(&self) -> bool {
	self.bytes().all(\|b\| b.is_ascii_hexdigit())
	}

	#[inline]
	fn is_ascii_punctuation(&self) -> bool {
	self.bytes().all(\|b\| b.is_ascii_punctuation())
	}

	#[inline]
	fn is_ascii_graphic(&self) -> bool {
	self.bytes().all(\|b\| b.is_ascii_graphic())
	}

	#[inline]
	fn is_ascii_whitespace(&self) -> bool {
	self.bytes().all(\|b\| b.is_ascii_whitespace())
	}

	#[inline]
	fn is_ascii_control(&self) -> bool {
	self.bytes().all(\|b\| b.is_ascii_control())
	}
	}

	impl AsciiExt for [u8] {
	type Owned = Vec<u8>;
	#[inline]
	fn is_ascii(&self) -> bool {
	self.iter().all(\|b\| b.is_ascii())
	}

	#[inline]
	fn to_ascii_uppercase(&self) -> Vec<u8> {
	let mut me = self.to_vec();
	me.make_ascii_uppercase();
	return me
	}

	#[inline]
	fn to_ascii_lowercase(&self) -> Vec<u8> {
	let mut me = self.to_vec();
	me.make_ascii_lowercase();
	return me
	}

	#[inline]
	fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool {
	self.len() == other.len() &&
	self.iter().zip(other).all(\|(a, b)\| {
	a.eq_ignore_ascii_case(b)
	})
	}

	fn make_ascii_uppercase(&mut self) {
	for byte in self {
	byte.make_ascii_uppercase();
	}
	}

	fn make_ascii_lowercase(&mut self) {
	for byte in self {
	byte.make_ascii_lowercase();
	}
	}

	#[inline]
	fn is_ascii_alphabetic(&self) -> bool {
	self.iter().all(\|b\| b.is_ascii_alphabetic())
	}

	#[inline]
	fn is_ascii_uppercase(&self) -> bool {
	self.iter().all(\|b\| b.is_ascii_uppercase())
	}

	#[inline]
	fn is_ascii_lowercase(&self) -> bool {
	self.iter().all(\|b\| b.is_ascii_lowercase())
	}

	#[inline]
	fn is_ascii_alphanumeric(&self) -> bool {
	self.iter().all(\|b\| b.is_ascii_alphanumeric())
	}

	#[inline]
	fn is_ascii_digit(&self) -> bool {
	self.iter().all(\|b\| b.is_ascii_digit())
	}

	#[inline]
	fn is_ascii_hexdigit(&self) -> bool {
	self.iter().all(\|b\| b.is_ascii_hexdigit())
	}

	#[inline]
	fn is_ascii_punctuation(&self) -> bool {
	self.iter().all(\|b\| b.is_ascii_punctuation())
	}

	#[inline]
	fn is_ascii_graphic(&self) -> bool {
	self.iter().all(\|b\| b.is_ascii_graphic())
	}

	#[inline]
	fn is_ascii_whitespace(&self) -> bool {
	self.iter().all(\|b\| b.is_ascii_whitespace())
	}

	#[inline]
	fn is_ascii_control(&self) -> bool {
	self.iter().all(\|b\| b.is_ascii_control())
	}
	}

	impl AsciiExt for u8 {
	type Owned = u8;
	#[inline]
	fn is_ascii(&self) -> bool { *self & 128 == 0 }
	#[inline]
	fn to_ascii_uppercase(&self) -> u8 { ASCII_UPPERCASE_MAP[*self as usize] }
	#[inline]
	fn to_ascii_lowercase(&self) -> u8 { ASCII_LOWERCASE_MAP[*self as usize] }
	#[inline]
	fn eq_ignore_ascii_case(&self, other: &u8) -> bool {
	self.to_ascii_lowercase() == other.to_ascii_lowercase()
	}
	#[inline]
	fn make_ascii_uppercase(&mut self) { *self = self.to_ascii_uppercase(); }
	#[inline]
	fn make_ascii_lowercase(&mut self) { *self = self.to_ascii_lowercase(); }

	#[inline]
	fn is_ascii_alphabetic(&self) -> bool {
	if *self >= 0x80 { return false; }
	match ASCII_CHARACTER_CLASS[*self as usize] {
	L\|Lx\|U\|Ux => true,
	_ => false
	}
	}

	#[inline]
	fn is_ascii_uppercase(&self) -> bool {
	if *self >= 0x80 { return false }
	match ASCII_CHARACTER_CLASS[*self as usize] {
	U\|Ux => true,
	_ => false
	}
	}

	#[inline]
	fn is_ascii_lowercase(&self) -> bool {
	if *self >= 0x80 { return false }
	match ASCII_CHARACTER_CLASS[*self as usize] {
	L\|Lx => true,
	_ => false
	}
	}

	#[inline]
	fn is_ascii_alphanumeric(&self) -> bool {
	if *self >= 0x80 { return false }
	match ASCII_CHARACTER_CLASS[*self as usize] {
	D\|L\|Lx\|U\|Ux => true,
	_ => false
	}
	}

	#[inline]
	fn is_ascii_digit(&self) -> bool {
	if *self >= 0x80 { return false }
	match ASCII_CHARACTER_CLASS[*self as usize] {
	D => true,
	_ => false
	}
	}

	#[inline]
	fn is_ascii_hexdigit(&self) -> bool {
	if *self >= 0x80 { return false }
	match ASCII_CHARACTER_CLASS[*self as usize] {
	D\|Lx\|Ux => true,
	_ => false
	}
	}

	#[inline]
	fn is_ascii_punctuation(&self) -> bool {
	if *self >= 0x80 { return false }
	match ASCII_CHARACTER_CLASS[*self as usize] {
	P => true,
	_ => false
	}
	}

	#[inline]
	fn is_ascii_graphic(&self) -> bool {
	if *self >= 0x80 { return false; }
	match ASCII_CHARACTER_CLASS[*self as usize] {
	Ux\|U\|Lx\|L\|D\|P => true,
	_ => false
	}
	}

	#[inline]
	fn is_ascii_whitespace(&self) -> bool {
	if *self >= 0x80 { return false; }
	match ASCII_CHARACTER_CLASS[*self as usize] {
	Cw\|W => true,
	_ => false
	}
	}

	#[inline]
	fn is_ascii_control(&self) -> bool {
	if *self >= 0x80 { return false; }
	match ASCII_CHARACTER_CLASS[*self as usize] {
	C\|Cw => true,
	_ => false
	}
	}
	}

	impl AsciiExt for char {
	type Owned = char;
	#[inline]
	fn is_ascii(&self) -> bool {
	*self as u32 <= 0x7F
	}

	#[inline]
	fn to_ascii_uppercase(&self) -> char {
	if self.is_ascii() {
	(*self as u8).to_ascii_uppercase() as char
	} else {
	*self
	}
	}

	#[inline]
	fn to_ascii_lowercase(&self) -> char {
	if self.is_ascii() {
	(*self as u8).to_ascii_lowercase() as char
	} else {
	*self
	}
	}

	#[inline]
	fn eq_ignore_ascii_case(&self, other: &char) -> bool {
	self.to_ascii_lowercase() == other.to_ascii_lowercase()
	}

	#[inline]
	fn make_ascii_uppercase(&mut self) { *self = self.to_ascii_uppercase(); }
	#[inline]
	fn make_ascii_lowercase(&mut self) { *self = self.to_ascii_lowercase(); }

	#[inline]
	fn is_ascii_alphabetic(&self) -> bool {
	(self as u32 <= 0x7f) && (self as u8).is_ascii_alphabetic()
	}

	#[inline]
	fn is_ascii_uppercase(&self) -> bool {
	(self as u32 <= 0x7f) && (self as u8).is_ascii_uppercase()
	}

	#[inline]
	fn is_ascii_lowercase(&self) -> bool {
	(self as u32 <= 0x7f) && (self as u8).is_ascii_lowercase()
	}

	#[inline]
	fn is_ascii_alphanumeric(&self) -> bool {
	(self as u32 <= 0x7f) && (self as u8).is_ascii_alphanumeric()
	}

	#[inline]
	fn is_ascii_digit(&self) -> bool {
	(self as u32 <= 0x7f) && (self as u8).is_ascii_digit()
	}

	#[inline]
	fn is_ascii_hexdigit(&self) -> bool {
	(self as u32 <= 0x7f) && (self as u8).is_ascii_hexdigit()
	}

	#[inline]
	fn is_ascii_punctuation(&self) -> bool {
	(self as u32 <= 0x7f) && (self as u8).is_ascii_punctuation()
	}

	#[inline]
	fn is_ascii_graphic(&self) -> bool {
	(self as u32 <= 0x7f) && (self as u8).is_ascii_graphic()
	}

	#[inline]
	fn is_ascii_whitespace(&self) -> bool {
	(self as u32 <= 0x7f) && (self as u8).is_ascii_whitespace()
	}

	#[inline]
	fn is_ascii_control(&self) -> bool {
	(self as u32 <= 0x7f) && (self as u8).is_ascii_control()
	}
	}

	/// An iterator over the escaped version of a byte.
	///
	/// This `struct` is created by the [`escape_default`] function. See its
	/// documentation for more.
	///
	pub struct EscapeDefault {
	range: Range<usize>,
	data: [u8; 4],
	}

	/// Returns an iterator that produces an escaped version of a `u8`.
	///
	/// The default is chosen with a bias toward producing literals that are
	/// legal in a variety of languages, including C++11 and similar C-family
	/// languages. The exact rules are:
	///
	/// - Tab, CR and LF are escaped as '\t', '\r' and '\n' respectively.
	/// - Single-quote, double-quote and backslash chars are backslash-escaped.
	/// - Any other chars in the range [0x20,0x7e] are not escaped.
	/// - Any other chars are given hex escapes of the form '\xNN'.
	/// - Unicode escapes are never generated by this function.
	///
	pub fn escape_default(c: u8) -> EscapeDefault {
	let (data, len) = match c {
	b'\t' => ([b'\\', b't', 0, 0], 2),
	b'\r' => ([b'\\', b'r', 0, 0], 2),
	b'\n' => ([b'\\', b'n', 0, 0], 2),
	b'\\' => ([b'\\', b'\\', 0, 0], 2),
	b'\'' => ([b'\\', b'\'', 0, 0], 2),
	b'"' => ([b'\\', b'"', 0, 0], 2),
	b'\x20' ... b'\x7e' => ([c, 0, 0, 0], 1),
	_ => ([b'\\', b'x', hexify(c >> 4), hexify(c & 0xf)], 4),
	};

	return EscapeDefault { range: (0.. len), data: data };

	fn hexify(b: u8) -> u8 {
	match b {
	0 ... 9 => b'0' + b,
	_ => b'a' + b - 10,
	}
	}
	}

	impl Iterator for EscapeDefault {
	type Item = u8;
	fn next(&mut self) -> Option<u8> { self.range.next().map(\|i\| self.data[i]) }
	fn size_hint(&self) -> (usize, Option<usize>) { self.range.size_hint() }
	}

	impl DoubleEndedIterator for EscapeDefault {
	fn next_back(&mut self) -> Option<u8> {
	self.range.next_back().map(\|i\| self.data[i])
	}
	}

	impl ExactSizeIterator for EscapeDefault {}

	impl FusedIterator for EscapeDefault {}

	impl fmt::Debug for EscapeDefault {
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
	f.pad("EscapeDefault { .. }")
	}
	}

	static ASCII_LOWERCASE_MAP: [u8; 256] = [
	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
	b' ', b'!', b'"', b'#', b'$', b'%', b'&', b'\'',
	b'(', b')', b'*', b'+', b',', b'-', b'.', b'/',
	b'0', b'1', b'2', b'3', b'4', b'5', b'6', b'7',
	b'8', b'9', b':', b';', b'<', b'=', b'>', b'?',
	b'@',

	b'a', b'b', b'c', b'd', b'e', b'f', b'g',
	b'h', b'i', b'j', b'k', b'l', b'm', b'n', b'o',
	b'p', b'q', b'r', b's', b't', b'u', b'v', b'w',
	b'x', b'y', b'z',

	b'[', b'\\', b']', b'^', b'_',
	b'`', b'a', b'b', b'c', b'd', b'e', b'f', b'g',
	b'h', b'i', b'j', b'k', b'l', b'm', b'n', b'o',
	b'p', b'q', b'r', b's', b't', b'u', b'v', b'w',
	b'x', b'y', b'z', b'{', b'\|', b'}', b'~', 0x7f,
	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
	0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
	0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
	0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
	0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
	0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
	0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
	0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
	0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
	0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
	0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
	0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
	0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
	0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
	0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff,
	];

	static ASCII_UPPERCASE_MAP: [u8; 256] = [
	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
	b' ', b'!', b'"', b'#', b'$', b'%', b'&', b'\'',
	b'(', b')', b'*', b'+', b',', b'-', b'.', b'/',
	b'0', b'1', b'2', b'3', b'4', b'5', b'6', b'7',
	b'8', b'9', b':', b';', b'<', b'=', b'>', b'?',
	b'@', b'A', b'B', b'C', b'D', b'E', b'F', b'G',
	b'H', b'I', b'J', b'K', b'L', b'M', b'N', b'O',
	b'P', b'Q', b'R', b'S', b'T', b'U', b'V', b'W',
	b'X', b'Y', b'Z', b'[', b'\\', b']', b'^', b'_',
	b'`',

	b'A', b'B', b'C', b'D', b'E', b'F', b'G',
	b'H', b'I', b'J', b'K', b'L', b'M', b'N', b'O',
	b'P', b'Q', b'R', b'S', b'T', b'U', b'V', b'W',
	b'X', b'Y', b'Z',

	b'{', b'\|', b'}', b'~', 0x7f,
	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
	0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
	0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
	0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
	0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
	0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
	0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
	0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
	0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
	0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
	0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
	0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
	0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
	0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
	0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff,
	];

	enum AsciiCharacterClass {
	C, // control
	Cw, // control whitespace
	W, // whitespace
	D, // digit
	L, // lowercase
	Lx, // lowercase hex digit
	U, // uppercase
	Ux, // uppercase hex digit
	P, // punctuation
	}
	use self::AsciiCharacterClass::*;

	static ASCII_CHARACTER_CLASS: [AsciiCharacterClass; 128] = [
	// _0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _a _b _c _d _e _f
	C, C, C, C, C, C, C, C, C, Cw,Cw,C, Cw,Cw,C, C, // 0_
	C, C, C, C, C, C, C, C, C, C, C, C, C, C, C, C, // 1_
	W, P, P, P, P, P, P, P, P, P, P, P, P, P, P, P, // 2_
	D, D, D, D, D, D, D, D, D, D, P, P, P, P, P, P, // 3_
	P, Ux,Ux,Ux,Ux,Ux,Ux,U, U, U, U, U, U, U, U, U, // 4_
	U, U, U, U, U, U, U, U, U, U, U, P, P, P, P, P, // 5_
	P, Lx,Lx,Lx,Lx,Lx,Lx,L, L, L, L, L, L, L, L, L, // 6_
	L, L, L, L, L, L, L, L, L, L, L, P, P, P, P, C, // 7_
	];