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237 lines
8 KiB
C++
237 lines
8 KiB
C++
/*
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* FTGL - OpenGL font library
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*
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* Copyright (c) 2008 Daniel Remenak <dtremenak@users.sourceforge.net>
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*
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* Portions derived from ConvertUTF.c Copyright (C) 2001-2004 Unicode, Inc
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* Unicode, Inc. hereby grants the right to freely use the information
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* supplied in this file in the creation of products supporting the
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* Unicode Standard, and to make copies of this file in any form
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* for internal or external distribution as long as this notice
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* remains attached.
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#ifndef __FTUnicode__
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#define __FTUnicode__
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/**
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* Provides a way to easily walk multibyte unicode strings in the various
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* Unicode encodings (UTF-8, UTF-16, UTF-32, UCS-2, and UCS-4). Encodings
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* with elements larger than one byte must already be in the correct endian
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* order for the current architecture.
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*/
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template <typename T>
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class FTUnicodeStringItr
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{
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public:
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/**
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* Constructor. Also reads the first character and stores it.
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*
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* @param string The buffer to iterate. No copy is made.
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*/
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FTUnicodeStringItr(const T* string) : curPos(string), nextPos(string)
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{
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(*this)++;
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};
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/**
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* Pre-increment operator. Reads the next unicode character and sets
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* the state appropriately.
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* Note - not protected against overruns.
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*/
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FTUnicodeStringItr& operator++()
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{
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curPos = nextPos;
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// unicode handling
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switch (sizeof(T))
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{
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case 1: // UTF-8
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// get this character
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readUTF8(); break;
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case 2: // UTF-16
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readUTF16(); break;
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case 4: // UTF-32
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// fall through
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default: // error condition really, but give it a shot anyway
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curChar = *nextPos++;
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}
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return *this;
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}
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/**
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* Post-increment operator. Reads the next character and sets
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* the state appropriately.
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* Note - not protected against overruns.
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*/
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FTUnicodeStringItr operator++(int)
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{
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FTUnicodeStringItr temp = *this;
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++*this;
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return temp;
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}
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/**
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* Equality operator. Two FTUnicodeStringItrs are considered equal
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* if they have the same current buffer and buffer position.
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*/
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bool operator==(const FTUnicodeStringItr& right) const
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{
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if (curPos == right.getBufferFromHere())
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return true;
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return false;
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}
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/**
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* Dereference operator.
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*
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* @return The unicode codepoint of the character currently pointed
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* to by the FTUnicodeStringItr.
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*/
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unsigned int operator*() const
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{
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return curChar;
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}
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/**
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* Buffer-fetching getter. You can use this to retreive the buffer
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* starting at the currently-iterated character for functions which
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* require a Unicode string as input.
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*/
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const T* getBufferFromHere() const { return curPos; }
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private:
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/**
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* Helper function for reading a single UTF8 character from the string.
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* Updates internal state appropriately.
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*/
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void readUTF8();
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/**
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* Helper function for reading a single UTF16 character from the string.
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* Updates internal state appropriately.
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*/
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void readUTF16();
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/**
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* The buffer position of the first element in the current character.
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*/
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const T* curPos;
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/**
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* The character stored at the current buffer position (prefetched on
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* increment, so there's no penalty for dereferencing more than once).
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*/
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unsigned int curChar;
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/**
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* The buffer position of the first element in the next character.
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*/
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const T* nextPos;
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// unicode magic numbers
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static const char utf8bytes[256];
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static const unsigned long offsetsFromUTF8[6];
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static const unsigned long highSurrogateStart;
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static const unsigned long highSurrogateEnd;
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static const unsigned long lowSurrogateStart;
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static const unsigned long lowSurrogateEnd;
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static const unsigned long highSurrogateShift;
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static const unsigned long lowSurrogateBase;
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};
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/* The first character in a UTF8 sequence indicates how many bytes
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* to read (among other things) */
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template <typename T>
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const char FTUnicodeStringItr<T>::utf8bytes[256] = {
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
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2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
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3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3, 4,4,4,4,4,4,4,4,5,5,5,5,6,6,6,6
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};
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/* Magic values subtracted from a buffer value during UTF8 conversion.
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* This table contains as many values as there might be trailing bytes
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* in a UTF-8 sequence. */
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template <typename T>
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const unsigned long FTUnicodeStringItr<T>::offsetsFromUTF8[6] = { 0x00000000UL, 0x00003080UL, 0x000E2080UL,
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0x03C82080UL, 0xFA082080UL, 0x82082080UL };
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// get a UTF8 character; leave the tracking pointer at the start of the
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// next character
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// not protected against invalid UTF8
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template <typename T>
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inline void FTUnicodeStringItr<T>::readUTF8()
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{
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unsigned int ch = 0;
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unsigned int extraBytesToRead = utf8bytes[(unsigned char)(*nextPos)];
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// falls through
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switch (extraBytesToRead)
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{
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case 6: ch += *nextPos++; ch <<= 6; /* remember, illegal UTF-8 */
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case 5: ch += *nextPos++; ch <<= 6; /* remember, illegal UTF-8 */
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case 4: ch += *nextPos++; ch <<= 6;
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case 3: ch += *nextPos++; ch <<= 6;
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case 2: ch += *nextPos++; ch <<= 6;
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case 1: ch += *nextPos++;
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}
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ch -= offsetsFromUTF8[extraBytesToRead-1];
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curChar = ch;
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}
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// Magic numbers for UTF-16 conversions
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template <typename T>
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const unsigned long FTUnicodeStringItr<T>::highSurrogateStart = 0xD800;
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template <typename T>
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const unsigned long FTUnicodeStringItr<T>::highSurrogateEnd = 0xDBFF;
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template <typename T>
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const unsigned long FTUnicodeStringItr<T>::lowSurrogateStart = 0xDC00;
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template <typename T>
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const unsigned long FTUnicodeStringItr<T>::lowSurrogateEnd = 0xDFFF;
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template <typename T>
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const unsigned long FTUnicodeStringItr<T>::highSurrogateShift = 10;
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template <typename T>
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const unsigned long FTUnicodeStringItr<T>::lowSurrogateBase = 0x0010000UL;
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template <typename T>
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inline void FTUnicodeStringItr<T>::readUTF16()
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{
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unsigned int ch = *nextPos++;
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// if we have the first half of the surrogate pair
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if (ch >= highSurrogateStart && ch <= highSurrogateEnd)
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{
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unsigned int ch2 = *curPos;
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// complete the surrogate pair
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if (ch2 >= lowSurrogateStart && ch2 <= lowSurrogateEnd)
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{
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ch = ((ch - highSurrogateStart) << highSurrogateShift)
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+ (ch2 - lowSurrogateStart) + lowSurrogateBase;
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++nextPos;
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}
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}
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curChar = ch;
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}
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#endif
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