262 lines
8.5 KiB
C++
262 lines
8.5 KiB
C++
// Copyright 2006 Nemanja Trifunovic
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/*
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Permission is hereby granted, free of charge, to any person or organization
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obtaining a copy of the software and accompanying documentation covered by
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this license (the "Software") to use, reproduce, display, distribute,
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execute, and transmit the Software, and to prepare derivative works of the
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Software, and to permit third-parties to whom the Software is furnished to
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do so, all subject to the following:
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The copyright notices in the Software and this entire statement, including
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the above license grant, this restriction and the following disclaimer,
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must be included in all copies of the Software, in whole or in part, and
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all derivative works of the Software, unless such copies or derivative
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works are solely in the form of machine-executable object code generated by
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a source language processor.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
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SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
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FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
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ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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DEALINGS IN THE SOFTWARE.
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*/
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#ifndef UTF8_FOR_CPP_CORE_H_2675DCD0_9480_4c0c_B92A_CC14C027B731
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#define UTF8_FOR_CPP_CORE_H_2675DCD0_9480_4c0c_B92A_CC14C027B731
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#include <iterator>
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namespace utf8
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{
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// The typedefs for 8-bit, 16-bit and 32-bit unsigned integers
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// You may need to change them to match your system.
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// These typedefs have the same names as ones from cstdint, or boost/cstdint
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typedef unsigned char uint8_t;
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typedef unsigned short uint16_t;
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typedef unsigned int uint32_t;
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// Helper code - not intended to be directly called by the library users. May be changed at any time
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namespace internal
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{
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// Unicode constants
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// Leading (high) surrogates: 0xd800 - 0xdbff
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// Trailing (low) surrogates: 0xdc00 - 0xdfff
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const uint16_t LEAD_SURROGATE_MIN = 0xd800u;
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const uint16_t LEAD_SURROGATE_MAX = 0xdbffu;
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const uint16_t TRAIL_SURROGATE_MIN = 0xdc00u;
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const uint16_t TRAIL_SURROGATE_MAX = 0xdfffu;
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const uint16_t LEAD_OFFSET = LEAD_SURROGATE_MIN - (0x10000 >> 10);
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const uint32_t SURROGATE_OFFSET = 0x10000u - (LEAD_SURROGATE_MIN << 10) - TRAIL_SURROGATE_MIN;
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// Maximum valid value for a Unicode code point
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const uint32_t CODE_POINT_MAX = 0x0010ffffu;
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template<typename octet_type>
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inline uint8_t mask8(octet_type oc)
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{
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return static_cast<uint8_t>(0xff & oc);
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}
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template<typename u16_type>
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inline uint16_t mask16(u16_type oc)
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{
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return static_cast<uint16_t>(0xffff & oc);
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}
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template<typename octet_type>
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inline bool is_trail(octet_type oc)
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{
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return ((mask8(oc) >> 6) == 0x2);
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}
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template <typename u16>
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inline bool is_surrogate(u16 cp)
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{
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return (cp >= LEAD_SURROGATE_MIN && cp <= TRAIL_SURROGATE_MAX);
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}
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template <typename u32>
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inline bool is_code_point_valid(u32 cp)
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{
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return (cp <= CODE_POINT_MAX && !is_surrogate(cp) && cp != 0xfffe && cp != 0xffff);
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}
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template <typename octet_iterator>
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inline typename std::iterator_traits<octet_iterator>::difference_type
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sequence_length(octet_iterator lead_it)
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{
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uint8_t lead = mask8(*lead_it);
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if (lead < 0x80)
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return 1;
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else if ((lead >> 5) == 0x6)
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return 2;
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else if ((lead >> 4) == 0xe)
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return 3;
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else if ((lead >> 3) == 0x1e)
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return 4;
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else
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return 0;
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}
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enum utf_error {OK, NOT_ENOUGH_ROOM, INVALID_LEAD, INCOMPLETE_SEQUENCE, OVERLONG_SEQUENCE, INVALID_CODE_POINT};
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template <typename octet_iterator>
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utf_error validate_next(octet_iterator& it, octet_iterator end, uint32_t* code_point)
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{
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uint32_t cp = mask8(*it);
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// Check the lead octet
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typedef typename std::iterator_traits<octet_iterator>::difference_type octet_differece_type;
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octet_differece_type length = sequence_length(it);
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// "Shortcut" for ASCII characters
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if (length == 1) {
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if (end - it > 0) {
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if (code_point)
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*code_point = cp;
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++it;
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return OK;
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}
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else
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return NOT_ENOUGH_ROOM;
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}
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// Do we have enough memory?
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if (end - it < length)
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return NOT_ENOUGH_ROOM;
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// Check trail octets and calculate the code point
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switch (length) {
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case 0:
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return INVALID_LEAD;
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break;
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case 2:
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if (is_trail(*(++it))) {
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cp = ((cp << 6) & 0x7ff) + ((*it) & 0x3f);
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}
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else {
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--it;
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return INCOMPLETE_SEQUENCE;
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}
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break;
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case 3:
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if (is_trail(*(++it))) {
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cp = ((cp << 12) & 0xffff) + ((mask8(*it) << 6) & 0xfff);
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if (is_trail(*(++it))) {
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cp += (*it) & 0x3f;
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}
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else {
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--it; --it;
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return INCOMPLETE_SEQUENCE;
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}
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}
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else {
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--it;
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return INCOMPLETE_SEQUENCE;
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}
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break;
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case 4:
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if (is_trail(*(++it))) {
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cp = ((cp << 18) & 0x1fffff) + ((mask8(*it) << 12) & 0x3ffff);
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if (is_trail(*(++it))) {
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cp += (mask8(*it) << 6) & 0xfff;
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if (is_trail(*(++it))) {
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cp += (*it) & 0x3f;
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}
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else {
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--it; --it; --it;
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return INCOMPLETE_SEQUENCE;
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}
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}
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else {
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--it; --it;
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return INCOMPLETE_SEQUENCE;
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}
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}
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else {
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--it;
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return INCOMPLETE_SEQUENCE;
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}
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break;
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}
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// Is the code point valid?
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if (!is_code_point_valid(cp)) {
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for (octet_differece_type i = 0; i < length - 1; ++i)
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--it;
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return INVALID_CODE_POINT;
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}
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if (code_point)
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*code_point = cp;
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if (cp < 0x80) {
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if (length != 1) {
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for (octet_differece_type i = 0; i < length - 1; ++i)
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--it;
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return OVERLONG_SEQUENCE;
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}
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}
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else if (cp < 0x800) {
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if (length != 2) {
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for (octet_differece_type i = 0; i < length - 1; ++i)
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--it;
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return OVERLONG_SEQUENCE;
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}
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}
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else if (cp < 0x10000) {
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if (length != 3) {
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for (octet_differece_type i = 0; i < length - 1; ++i)
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--it;
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return OVERLONG_SEQUENCE;
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}
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}
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++it;
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return OK;
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}
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template <typename octet_iterator>
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inline utf_error validate_next(octet_iterator& it, octet_iterator end) {
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return validate_next(it, end, 0);
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}
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} // namespace internal
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/// The library API - functions intended to be called by the users
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// Byte order mark
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const uint8_t bom[] = {0xef, 0xbb, 0xbf};
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template <typename octet_iterator>
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octet_iterator find_invalid(octet_iterator start, octet_iterator end)
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{
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octet_iterator result = start;
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while (result != end) {
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internal::utf_error err_code = internal::validate_next(result, end);
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if (err_code != internal::OK)
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return result;
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}
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return result;
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}
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template <typename octet_iterator>
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inline bool is_valid(octet_iterator start, octet_iterator end)
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{
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return (find_invalid(start, end) == end);
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}
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template <typename octet_iterator>
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inline bool is_bom (octet_iterator it)
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{
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return (
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(internal::mask8(*it++)) == bom[0] &&
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(internal::mask8(*it++)) == bom[1] &&
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(internal::mask8(*it)) == bom[2]
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);
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}
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} // namespace utf8
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#endif // header guard
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