cute_utf.h

/*
	------------------------------------------------------------------------------
		Licensing information can be found at the end of the file.
	------------------------------------------------------------------------------

	cute_utf.h v1.0

	To create implementation (the function definitions)
		#define CUTE_UTF_IMPLEMENTATION
	in *one* C/CPP file (translation unit) that includes this file

	SUMMARY:
	cute_utf is primarily for the use of utf8 encoding. There is a great website
	called http://utf8everywhere.org/ that contains a lot of great info. The
	gist is that utf8 is quite superior to all other encodings and should be
	used for pretty much everything all the time.

	This header is mostly useful for applications that want to localize or become
	utf8-aware, or to future proof code. This header was especially designed to
	facilitate game localization.

	EXTRA INFO:
	Some advantages of utf8:
	* Can encode anything utf32 can encode
	* Is very widely used on the web and everywhere else
	* Completely backwards compatible with typical ASCII
	* Operations in utf8 buffers can be coded naively as if it were a regular
	  old ASCII buffer
	* utf8 buffers can always be treated as a naive byte buffer making the utf8
	  encoding scheme safe as an opaque data type
	* Endianness independent
	* Lexicographic sorting is identical to utf32 sorting

	Unfortunately when dealing with Windows functions many APIs accept utf16
	encodings in the form of wchar_t. As a response this header provides some
	utilities for on-the-fly conversions to use utf16. The utf8everwhere site
	makes some great arguments to defend this style, so I highly recommend
	reading it if anyone cares.

	CONVERSIONS:
	To convert from utf8 to utf16 use cu_decode8, and pass the codepoint into the
	cu_encode16 function.

	As additional API there are cu_widen and cu_narrow funcs to operate on arrays.
	cu_widen converts utf8 to wchar_t (utf16) and cu_shorten converts utf16 back to
	utf8. Typically these helpers are to facilitate Windows APIs (pretty much
	what MultiByteToWideChar was for). Each function takes as input the size of
	the utf8 array, since this size should always be known. Just size the wide
	array to worst case size (2x number of bytes).

	One last trick on Windows is for using utf8 strings to for dealing with file
	paths. Since utf8 strings cannot be forwarded directly to fopen (or similar
	functions) GetShortPathName should be used. On other platforms symlinks can
	be utilized.

	Here is a post about this header:
	http://www.randygaul.net/2017/02/23/game-localization-and-utf-8/

	CREDIT:
	The utf8 encoder/decoder was written by Richard Mitton for his lovely tigr
	library. His functions have been tenderly extracted and have found a new
	home in this header; they form the most important part of this header so
	a big thanks goes to Mitton for kindly releasing his code to public domain!
*/

#if !defined(CUTE_UTF_H)
#define CUTE_UTF_H

#ifndef _CRT_SECURE_NO_WARNINGS
#define _CRT_SECURE_NO_WARNINGS
#endif
#include <wchar.h>

// reads text and will return text + 1..4 depending on the decoded code point
// the code point is stored in cp
const char* cu_decode8(const char* text, int* cp);

// reads text and will return text + 1..4 depending on code point
char *cu_encode8(char *text, int cp);

// returns the number of bytes needed to encode the code point as utf8
int cu_codepoint8_size(int cp);

// reads text and will return text + 1..2 depending on decoded code point
// the code point is stored in cp
const wchar_t* cu_decode16(const wchar_t* text, int* cp);

// reads text and will return text + 1..2 depending on code point
wchar_t* cu_encode16(wchar_t* text, int cp);

// returns the number of bytes needed to encode the code point as utf16
int cu_codepoint16_size(int cp);

// converts utf8 `in` to "wide" format utf16 `out`
void cu_widen(const char* in, wchar_t* out);

// converts utf16 `in` to "wide" format utf8 `out`
void cu_shorten(const wchar_t* in, char* out);

// additional overloads
#ifdef __cplusplus
void cu_widen(const char* in, int in_len, wchar_t* out);
void cu_widen(const char* in, wchar_t* out, int out_len);
void cu_widen(const char* in, int in_len, wchar_t* out, int out_len);
#endif

#ifdef __cplusplus
void cu_shorten(const wchar_t* in, int in_len, char* out);
void cu_shorten(const wchar_t* in, char* out, int out_len);
void cu_shorten(const wchar_t* in, int in_len, char* out, int out_len);
#endif

#endif

#ifdef CUTE_UTF_IMPLEMENTATION
#ifndef CUTE_UTF_IMPLEMENTATION_ONCE
#define CUTE_UTF_IMPLEMENTATION_ONCE

// utf8 functions created from RFC-3629

const char* cu_decode8(const char* text, int* cp)
{
	unsigned char c = *text++;
	int extra = 0, min = 0;
	*cp = 0;
	     if (c >= 0xF0) { *cp = c & 0x07; extra = 3; min = 0x10000; }
	else if (c >= 0xE0) { *cp = c & 0x0F; extra = 2; min = 0x800; }
	else if (c >= 0xC0) { *cp = c & 0x1F; extra = 1; min = 0x80; }
	else if (c >= 0x80) { *cp = 0xFFFD; }
	else *cp = c;
	while (extra--)
	{
		c = *text++;
		if ((c & 0xC0) != 0x80) { *cp = 0xFFFD; break; }
		(*cp) = ((*cp) << 6) | (c & 0x3F);
	}
	if (*cp < min) *cp = 0xFFFD;
	return text;
}

char *cu_encode8(char *text, int cp)
{
	if (cp < 0 || cp > 0x10FFFF) cp = 0xFFFD;

#define CU_EMIT(X, Y, Z) *text++ = X | ((cp >> Y) & Z)
	     if (cp <    0x80) { CU_EMIT(0x00,0,0x7F); }
	else if (cp <   0x800) { CU_EMIT(0xC0,6,0x1F); CU_EMIT(0x80, 0,  0x3F); }
	else if (cp < 0x10000) { CU_EMIT(0xE0,12,0xF); CU_EMIT(0x80, 6,  0x3F); CU_EMIT(0x80, 0, 0x3F); }
	else                   { CU_EMIT(0xF0,18,0x7); CU_EMIT(0x80, 12, 0x3F); CU_EMIT(0x80, 6, 0x3F); CU_EMIT(0x80, 0, 0x3F); }
	return text;
}
#undef CU_EMIT

int cu_codepoint8_size(int cp)
{
	if (cp < 0 || cp > 0x10FFFF) cp = 0xFFFD;
	     if (cp <    0x80) return 1;
	else if (cp <   0x800) return 2;
	else if (cp < 0x10000) return 3;
	else                   return 4;
}

// utf16 functions created via RFC-2781

const wchar_t* cu_decode16(const wchar_t* text, int* cp)
{
	int in = *text++;
	if (in < 0xD800 || in > 0xDFFF) *cp = in;
	else if (in > 0xD800 && in < 0xDBFF) *cp = ((in & 0x03FF) << 10) | (*text++ & 0x03FF);
	else *cp = 0xFFFD;
	return text;
}

wchar_t* cu_encode16(wchar_t* text, int cp)
{
	if (cp < 0x10000) *text++ = cp;
	else
	{
		cp -= 0x10000;
		*text++ = 0xD800 | ((cp >> 10) & 0x03FF);
		*text++ = 0xDC00 | (cp & 0x03FF);
	}
	return text;
}

int cu_codepoint16_size(int cp)
{
	if (cp < 0x10000) return 1;
	else return 2;
}

void cu_widen(const char* in, wchar_t* out)
{
	int cp;
	while (*in)
	{
		in = cu_decode8(in, &cp);
		out = cu_encode16(out, cp);
	}
}

#ifdef __cplusplus
void cu_widen(const char* in, int in_len, wchar_t* out)
{
	const char* original = in;
	int cp;
	while (in < original + in_len)
	{
		in = cu_decode8(in, &cp);
		out = cu_encode16(out, cp);
	}
}

void cu_widen(const char* in, wchar_t* out, int out_len)
{
	wchar_t* original = out;
	int cp;
	while (*in && (out < original + out_len))
	{
		in = cu_decode8(in, &cp);
		out = cu_encode16(out, cp);
	}
}

void cu_widen(const char* in, int in_len, wchar_t* out, int out_len)
{
	const char* original_in = in;
	wchar_t* original_out = out;
	int cp;
	while ((in < original_in + in_len) && (out < original_out + out_len))
	{
		in = cu_decode8(in, &cp);
		out = cu_encode16(out, cp);
	}
}
#endif

void cu_shorten(const wchar_t* in, char* out)
{
	int cp;
	while (*in)
	{
		in = cu_decode16(in, &cp);
		out = cu_encode8(out, cp);
	}
}

#ifdef __cplusplus
void cu_shorten(const wchar_t* in, int in_len, char* out)
{
	const wchar_t* original = in;
	int cp;
	while (in < original + in_len)
	{
		in = cu_decode16(in, &cp);
		out = cu_encode8(out, cp);
	}
}

void cu_shorten(const wchar_t* in, char* out, int out_len)
{
	char* original = out;
	int cp;
	while (*in && (out < original + out_len))
	{
		in = cu_decode16(in, &cp);
		out = cu_encode8(out, cp);
	}
}

void cu_shorten(const wchar_t* in, int in_len, char* out, int out_len)
{
	const wchar_t* original_in = in;
	char* original_out = out;
	int cp;
	while ((in < original_in + in_len) && (out < original_out + out_len))
	{
		in = cu_decode16(in, &cp);
		out = cu_encode8(out, cp);
	}
}
#endif

#endif // CUTE_UTF_IMPLEMENTATION_ONCE
#endif // CUTE_UTF_IMPLEMENTATION

/*
	------------------------------------------------------------------------------
	This software is available under 2 licenses - you may choose the one you like.
	------------------------------------------------------------------------------
	ALTERNATIVE A - zlib license
	Copyright (c) 2017 Randy Gaul http://www.randygaul.net
	This software is provided 'as-is', without any express or implied warranty.
	In no event will the authors be held liable for any damages arising from
	the use of this software.
	Permission is granted to anyone to use this software for any purpose,
	including commercial applications, and to alter it and redistribute it
	freely, subject to the following restrictions:
	  1. The origin of this software must not be misrepresented; you must not
	     claim that you wrote the original software. If you use this software
	     in a product, an acknowledgment in the product documentation would be
	     appreciated but is not required.
	  2. Altered source versions must be plainly marked as such, and must not
	     be misrepresented as being the original software.
	  3. This notice may not be removed or altered from any source distribution.
	------------------------------------------------------------------------------
	ALTERNATIVE B - Public Domain (www.unlicense.org)
	This is free and unencumbered software released into the public domain.
	Anyone is free to copy, modify, publish, use, compile, sell, or distribute this 
	software, either in source code form or as a compiled binary, for any purpose, 
	commercial or non-commercial, and by any means.
	In jurisdictions that recognize copyright laws, the author or authors of this 
	software dedicate any and all copyright interest in the software to the public 
	domain. We make this dedication for the benefit of the public at large and to 
	the detriment of our heirs and successors. We intend this dedication to be an 
	overt act of relinquishment in perpetuity of all present and future rights to 
	this software under copyright law.
	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
	AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 
	ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 
	WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
	------------------------------------------------------------------------------
*/