455 lines
12 KiB
C++
455 lines
12 KiB
C++
//
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// Copyright (c) 2009-2011 Artyom Beilis (Tonkikh)
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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#ifndef BOOST_LOCALE_UTF_HPP_INCLUDED
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#define BOOST_LOCALE_UTF_HPP_INCLUDED
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#include <boost/cstdint.hpp>
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namespace boost {
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namespace locale {
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///
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/// \brief Namespace that holds basic operations on UTF encoded sequences
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///
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/// All functions defined in this namespace do not require linking with Boost.Locale library
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///
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namespace utf {
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/// \cond INTERNAL
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#ifdef __GNUC__
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# define BOOST_LOCALE_LIKELY(x) __builtin_expect((x),1)
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# define BOOST_LOCALE_UNLIKELY(x) __builtin_expect((x),0)
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#else
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# define BOOST_LOCALE_LIKELY(x) (x)
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# define BOOST_LOCALE_UNLIKELY(x) (x)
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#endif
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/// \endcond
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///
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/// \brief The integral type type that can hold a Unicode code point
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///
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typedef uint32_t code_point;
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///
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/// \brief Special constant that defines illegal code point
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///
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static const code_point illegal = 0xFFFFFFFFu;
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///
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/// \brief Special constant that defines incomplete code point
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///
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static const code_point incomplete = 0xFFFFFFFEu;
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///
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/// \brief the function checks if \a v is a valid code point
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///
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inline bool is_valid_codepoint(code_point v)
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{
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if(v>0x10FFFF)
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return false;
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if(0xD800 <=v && v<= 0xDFFF) // surragates
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return false;
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return true;
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}
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#ifdef BOOST_LOCALE_DOXYGEN
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///
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/// \brief UTF Traits class - functions to convert UTF sequences to and from Unicode code points
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///
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template<typename CharType,int size=sizeof(CharType)>
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struct utf_traits {
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///
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/// The type of the character
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///
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typedef CharType char_type;
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///
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/// Read one code point from the range [p,e) and return it.
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///
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/// - If the sequence that was read is incomplete sequence returns \ref incomplete,
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/// - If illegal sequence detected returns \ref illegal
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///
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/// Requirements
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///
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/// - Iterator is valid input iterator
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///
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/// Postconditions
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///
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/// - p points to the last consumed character
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///
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template<typename Iterator>
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static code_point decode(Iterator &p,Iterator e);
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///
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/// Maximal width of valid sequence in the code units:
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///
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/// - UTF-8 - 4
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/// - UTF-16 - 2
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/// - UTF-32 - 1
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///
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static const int max_width;
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///
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/// The width of specific code point in the code units.
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///
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/// Requirement: value is a valid Unicode code point
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/// Returns value in range [1..max_width]
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///
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static int width(code_point value);
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///
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/// Get the size of the trail part of variable length encoded sequence.
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///
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/// Returns -1 if C is not valid lead character
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///
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static int trail_length(char_type c);
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///
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/// Returns true if c is trail code unit, always false for UTF-32
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///
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static bool is_trail(char_type c);
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///
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/// Returns true if c is lead code unit, always true of UTF-32
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///
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static bool is_lead(char_type c);
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///
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/// Convert valid Unicode code point \a value to the UTF sequence.
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///
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/// Requirements:
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///
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/// - \a value is valid code point
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/// - \a out is an output iterator should be able to accept at least width(value) units
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///
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/// Returns the iterator past the last written code unit.
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///
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template<typename Iterator>
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static Iterator encode(code_point value,Iterator out);
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///
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/// Decodes valid UTF sequence that is pointed by p into code point.
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///
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/// If the sequence is invalid or points to end the behavior is undefined
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///
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template<typename Iterator>
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static code_point decode_valid(Iterator &p);
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};
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#else
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template<typename CharType,int size=sizeof(CharType)>
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struct utf_traits;
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template<typename CharType>
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struct utf_traits<CharType,1> {
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typedef CharType char_type;
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static int trail_length(char_type ci)
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{
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unsigned char c = ci;
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if(c < 128)
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return 0;
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if(BOOST_LOCALE_UNLIKELY(c < 194))
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return -1;
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if(c < 224)
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return 1;
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if(c < 240)
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return 2;
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if(BOOST_LOCALE_LIKELY(c <=244))
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return 3;
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return -1;
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}
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static const int max_width = 4;
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static int width(code_point value)
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{
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if(value <=0x7F) {
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return 1;
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}
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else if(value <=0x7FF) {
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return 2;
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}
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else if(BOOST_LOCALE_LIKELY(value <=0xFFFF)) {
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return 3;
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}
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else {
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return 4;
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}
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}
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static bool is_trail(char_type ci)
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{
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unsigned char c=ci;
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return (c & 0xC0)==0x80;
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}
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static bool is_lead(char_type ci)
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{
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return !is_trail(ci);
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}
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template<typename Iterator>
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static code_point decode(Iterator &p,Iterator e)
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{
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if(BOOST_LOCALE_UNLIKELY(p==e))
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return incomplete;
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unsigned char lead = *p++;
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// First byte is fully validated here
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int trail_size = trail_length(lead);
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if(BOOST_LOCALE_UNLIKELY(trail_size < 0))
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return illegal;
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//
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// Ok as only ASCII may be of size = 0
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// also optimize for ASCII text
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//
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if(trail_size == 0)
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return lead;
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code_point c = lead & ((1<<(6-trail_size))-1);
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// Read the rest
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unsigned char tmp;
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switch(trail_size) {
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case 3:
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if(BOOST_LOCALE_UNLIKELY(p==e))
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return incomplete;
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tmp = *p++;
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c = (c << 6) | ( tmp & 0x3F);
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case 2:
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if(BOOST_LOCALE_UNLIKELY(p==e))
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return incomplete;
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tmp = *p++;
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c = (c << 6) | ( tmp & 0x3F);
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case 1:
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if(BOOST_LOCALE_UNLIKELY(p==e))
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return incomplete;
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tmp = *p++;
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c = (c << 6) | ( tmp & 0x3F);
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}
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// Check code point validity: no surrogates and
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// valid range
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if(BOOST_LOCALE_UNLIKELY(!is_valid_codepoint(c)))
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return illegal;
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// make sure it is the most compact representation
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if(BOOST_LOCALE_UNLIKELY(width(c)!=trail_size + 1))
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return illegal;
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return c;
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}
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template<typename Iterator>
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static code_point decode_valid(Iterator &p)
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{
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unsigned char lead = *p++;
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if(lead < 192)
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return lead;
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int trail_size;
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if(lead < 224)
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trail_size = 1;
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else if(BOOST_LOCALE_LIKELY(lead < 240)) // non-BMP rare
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trail_size = 2;
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else
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trail_size = 3;
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code_point c = lead & ((1<<(6-trail_size))-1);
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switch(trail_size) {
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case 3:
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c = (c << 6) | ( static_cast<unsigned char>(*p++) & 0x3F);
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case 2:
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c = (c << 6) | ( static_cast<unsigned char>(*p++) & 0x3F);
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case 1:
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c = (c << 6) | ( static_cast<unsigned char>(*p++) & 0x3F);
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}
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return c;
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}
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template<typename Iterator>
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static Iterator encode(code_point value,Iterator out)
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{
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if(value <=0x7F) {
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*out++ = value;
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}
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else if(value <=0x7FF) {
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*out++=(value >> 6) | 0xC0;
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*out++=(value & 0x3F) | 0x80;
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}
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else if(BOOST_LOCALE_LIKELY(value <=0xFFFF)) {
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*out++=(value >> 12) | 0xE0;
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*out++=((value >> 6) & 0x3F) | 0x80;
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*out++=(value & 0x3F) | 0x80;
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}
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else {
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*out++=(value >> 18) | 0xF0;
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*out++=((value >> 12) & 0x3F) | 0x80;
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*out++=((value >> 6) & 0x3F) | 0x80;
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*out++=(value & 0x3F) | 0x80;
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}
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return out;
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}
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}; // utf8
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template<typename CharType>
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struct utf_traits<CharType,2> {
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typedef CharType char_type;
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// See RFC 2781
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static bool is_first_surrogate(uint16_t x)
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{
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return 0xD800 <=x && x<= 0xDBFF;
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}
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static bool is_second_surrogate(uint16_t x)
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{
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return 0xDC00 <=x && x<= 0xDFFF;
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}
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static code_point combine_surrogate(uint16_t w1,uint16_t w2)
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{
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return ((code_point(w1 & 0x3FF) << 10) | (w2 & 0x3FF)) + 0x10000;
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}
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static int trail_length(char_type c)
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{
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if(is_first_surrogate(c))
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return 1;
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if(is_second_surrogate(c))
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return -1;
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return 0;
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}
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///
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/// Returns true if c is trail code unit, always false for UTF-32
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///
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static bool is_trail(char_type c)
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{
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return is_second_surrogate(c);
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}
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///
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/// Returns true if c is lead code unit, always true of UTF-32
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///
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static bool is_lead(char_type c)
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{
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return !is_second_surrogate(c);
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}
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template<typename It>
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static code_point decode(It ¤t,It last)
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{
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if(BOOST_LOCALE_UNLIKELY(current == last))
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return incomplete;
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uint16_t w1=*current++;
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if(BOOST_LOCALE_LIKELY(w1 < 0xD800 || 0xDFFF < w1)) {
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return w1;
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}
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if(w1 > 0xDBFF)
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return illegal;
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if(current==last)
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return incomplete;
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uint16_t w2=*current++;
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if(w2 < 0xDC00 || 0xDFFF < w2)
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return illegal;
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return combine_surrogate(w1,w2);
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}
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template<typename It>
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static code_point decode_valid(It ¤t)
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{
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uint16_t w1=*current++;
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if(BOOST_LOCALE_LIKELY(w1 < 0xD800 || 0xDFFF < w1)) {
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return w1;
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}
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uint16_t w2=*current++;
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return combine_surrogate(w1,w2);
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}
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static const int max_width = 2;
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static int width(code_point u)
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{
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return u>=0x10000 ? 2 : 1;
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}
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template<typename It>
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static It encode(code_point u,It out)
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{
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if(BOOST_LOCALE_LIKELY(u<=0xFFFF)) {
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*out++ = u;
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}
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else {
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u-=0x10000;
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*out++=0xD800 | (u>>10);
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*out++=0xDC00 | (u & 0x3FF);
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}
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return out;
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}
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}; // utf16;
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template<typename CharType>
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struct utf_traits<CharType,4> {
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typedef CharType char_type;
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static int trail_length(char_type c)
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{
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if(is_valid_codepoint(c))
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return 0;
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return -1;
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}
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static bool is_trail(char_type /*c*/)
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{
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return false;
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}
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static bool is_lead(char_type /*c*/)
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{
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return true;
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}
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template<typename It>
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static code_point decode_valid(It ¤t)
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{
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return *current++;
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}
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template<typename It>
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static code_point decode(It ¤t,It last)
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{
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if(BOOST_LOCALE_UNLIKELY(current == last))
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return boost::locale::utf::incomplete;
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code_point c=*current++;
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if(BOOST_LOCALE_UNLIKELY(!is_valid_codepoint(c)))
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return boost::locale::utf::illegal;
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return c;
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}
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static const int max_width = 1;
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static int width(code_point /*u*/)
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{
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return 1;
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}
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template<typename It>
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static It encode(code_point u,It out)
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{
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*out++ = u;
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return out;
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}
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}; // utf32
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#endif
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} // utf
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} // locale
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} // boost
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#endif
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// vim: tabstop=4 expandtab shiftwidth=4 softtabstop=4
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