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RetroZilla/xpcom/string/public/nsUTF8Utils.h
Ryan Nematz 2f2ae146c0 first commit
2015-10-20 23:03:22 -04:00

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 2001
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Peter Annema <jaggernaut@netscape.com> (original author)
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef nsUTF8Utils_h_
#define nsUTF8Utils_h_
#include "nsCharTraits.h"
class UTF8traits
{
public:
static PRBool isASCII(char c) { return (c & 0x80) == 0x00; }
static PRBool isInSeq(char c) { return (c & 0xC0) == 0x80; }
static PRBool is2byte(char c) { return (c & 0xE0) == 0xC0; }
static PRBool is3byte(char c) { return (c & 0xF0) == 0xE0; }
static PRBool is4byte(char c) { return (c & 0xF8) == 0xF0; }
static PRBool is5byte(char c) { return (c & 0xFC) == 0xF8; }
static PRBool is6byte(char c) { return (c & 0xFE) == 0xFC; }
};
#ifdef __GNUC__
#define NS_ALWAYS_INLINE __attribute__((always_inline))
#else
#define NS_ALWAYS_INLINE
#endif
/**
* A character sink (see |copy_string| in nsAlgorithm.h) for converting
* UTF-8 to UTF-16
*/
class ConvertUTF8toUTF16
{
public:
typedef nsACString::char_type value_type;
typedef nsAString::char_type buffer_type;
ConvertUTF8toUTF16( buffer_type* aBuffer )
: mStart(aBuffer), mBuffer(aBuffer), mErrorEncountered(PR_FALSE) {}
size_t Length() const { return mBuffer - mStart; }
PRUint32 NS_ALWAYS_INLINE write( const value_type* start, PRUint32 N )
{
if ( mErrorEncountered )
return N;
// algorithm assumes utf8 units won't
// be spread across fragments
const value_type* p = start;
const value_type* end = start + N;
buffer_type* out = mBuffer;
for ( ; p != end /* && *p */; )
{
char c = *p++;
if ( UTF8traits::isASCII(c) )
{
*out++ = buffer_type(c);
continue;
}
PRUint32 ucs4;
PRUint32 minUcs4;
PRInt32 state = 0;
if ( UTF8traits::is2byte(c) )
{
ucs4 = (PRUint32(c) << 6) & 0x000007C0L;
state = 1;
minUcs4 = 0x00000080;
}
else if ( UTF8traits::is3byte(c) )
{
ucs4 = (PRUint32(c) << 12) & 0x0000F000L;
state = 2;
minUcs4 = 0x00000800;
}
else if ( UTF8traits::is4byte(c) )
{
ucs4 = (PRUint32(c) << 18) & 0x001F0000L;
state = 3;
minUcs4 = 0x00010000;
}
else if ( UTF8traits::is5byte(c) )
{
ucs4 = (PRUint32(c) << 24) & 0x03000000L;
state = 4;
minUcs4 = 0x00200000;
}
else if ( UTF8traits::is6byte(c) )
{
ucs4 = (PRUint32(c) << 30) & 0x40000000L;
state = 5;
minUcs4 = 0x04000000;
}
else
{
NS_ERROR("Not a UTF-8 string. This code should only be used for converting from known UTF-8 strings.");
mErrorEncountered = PR_TRUE;
mBuffer = out;
return N;
}
while ( state-- )
{
if (p == end)
{
NS_ERROR("Buffer ended in the middle of a multibyte sequence");
mErrorEncountered = PR_TRUE;
mBuffer = out;
return N;
}
c = *p++;
if ( UTF8traits::isInSeq(c) )
{
PRInt32 shift = state * 6;
ucs4 |= (PRUint32(c) & 0x3F) << shift;
}
else
{
NS_ERROR("not a UTF8 string");
mErrorEncountered = PR_TRUE;
mBuffer = out;
return N;
}
}
if ( ucs4 < minUcs4 )
{
// Overlong sequence
*out++ = UCS2_REPLACEMENT_CHAR;
}
else if ( ucs4 <= 0xD7FF )
{
*out++ = ucs4;
}
else if ( /* ucs4 >= 0xD800 && */ ucs4 <= 0xDFFF )
{
// Surrogates
*out++ = UCS2_REPLACEMENT_CHAR;
}
else if ( ucs4 == 0xFFFE || ucs4 == 0xFFFF )
{
// Prohibited characters
*out++ = UCS2_REPLACEMENT_CHAR;
}
else if ( ucs4 >= PLANE1_BASE )
{
if ( ucs4 >= UCS_END )
*out++ = UCS2_REPLACEMENT_CHAR;
else {
*out++ = (buffer_type)H_SURROGATE(ucs4);
*out++ = (buffer_type)L_SURROGATE(ucs4);
}
}
else
{
*out++ = ucs4;
}
}
mBuffer = out;
return p - start;
}
void write_terminator()
{
*mBuffer = buffer_type(0);
}
private:
buffer_type* const mStart;
buffer_type* mBuffer;
PRBool mErrorEncountered;
};
/**
* A character sink (see |copy_string| in nsAlgorithm.h) for computing
* the length of the UTF-16 string equivalent to a UTF-8 string.
*/
class CalculateUTF8Length
{
public:
typedef nsACString::char_type value_type;
CalculateUTF8Length() : mLength(0), mErrorEncountered(PR_FALSE) { }
size_t Length() const { return mLength; }
PRUint32 NS_ALWAYS_INLINE write( const value_type* start, PRUint32 N )
{
// ignore any further requests
if ( mErrorEncountered )
return N;
// algorithm assumes utf8 units won't
// be spread across fragments
const value_type* p = start;
const value_type* end = start + N;
for ( ; p < end /* && *p */; ++mLength )
{
if ( UTF8traits::isASCII(*p) )
p += 1;
else if ( UTF8traits::is2byte(*p) )
p += 2;
else if ( UTF8traits::is3byte(*p) )
p += 3;
else if ( UTF8traits::is4byte(*p) ) {
p += 4;
// Because a UTF-8 sequence of 4 bytes represents a codepoint
// greater than 0xFFFF, it will become a surrogate pair in the
// UTF-16 string, so add 1 more to mLength.
// This doesn't happen with is5byte and is6byte because they
// are illegal UTF-8 sequences (greater than 0x10FFFF) so get
// converted to a single replacement character.
//
// XXX: if the 4-byte sequence is an illegal non-shortest form,
// it also gets converted to a replacement character, so
// mLength will be off by one in this case.
++mLength;
}
else if ( UTF8traits::is5byte(*p) )
p += 5;
else if ( UTF8traits::is6byte(*p) )
p += 6;
else
{
break;
}
}
if ( p != end )
{
NS_ERROR("Not a UTF-8 string. This code should only be used for converting from known UTF-8 strings.");
mErrorEncountered = PR_TRUE;
return N;
}
return p - start;
}
private:
size_t mLength;
PRBool mErrorEncountered;
};
/**
* A character sink (see |copy_string| in nsAlgorithm.h) for converting
* UTF-16 to UTF-8.
*/
class ConvertUTF16toUTF8
{
public:
typedef nsAString::char_type value_type;
typedef nsACString::char_type buffer_type;
// The error handling here is more lenient than that in
// |ConvertUTF8toUTF16|, but it's that way for backwards
// compatibility.
ConvertUTF16toUTF8( buffer_type* aBuffer )
: mStart(aBuffer), mBuffer(aBuffer) {}
size_t Size() const { return mBuffer - mStart; }
PRUint32 NS_ALWAYS_INLINE write( const value_type* start, PRUint32 N )
{
buffer_type *out = mBuffer; // gcc isn't smart enough to do this!
for (const value_type *p = start, *end = start + N; p < end; ++p )
{
value_type c = *p;
if (! (c & 0xFF80)) // U+0000 - U+007F
{
*out++ = (char)c;
}
else if (! (c & 0xF800)) // U+0100 - U+07FF
{
*out++ = 0xC0 | (char)(c >> 6);
*out++ = 0x80 | (char)(0x003F & c);
}
else if (!IS_SURROGATE(c)) // U+0800 - U+D7FF,U+E000 - U+FFFF
{
*out++ = 0xE0 | (char)(c >> 12);
*out++ = 0x80 | (char)(0x003F & (c >> 6));
*out++ = 0x80 | (char)(0x003F & c );
}
else if (IS_HIGH_SURROGATE(c)) // U+D800 - U+DBFF
{
// D800- DBFF - High Surrogate
value_type h = c;
++p;
if (p == end)
{
NS_ERROR("Surrogate pair split between fragments");
mBuffer = out;
return N;
}
c = *p;
if (IS_LOW_SURROGATE(c))
{
// DC00- DFFF - Low Surrogate
// N = (H - D800) *400 + 10000 + ( L - DC00 )
PRUint32 ucs4 = SURROGATE_TO_UCS4(h, c);
// 0001 0000-001F FFFF
*out++ = 0xF0 | (char)(ucs4 >> 18);
*out++ = 0x80 | (char)(0x003F & (ucs4 >> 12));
*out++ = 0x80 | (char)(0x003F & (ucs4 >> 6));
*out++ = 0x80 | (char)(0x003F & ucs4);
}
else
{
NS_ERROR("got a High Surrogate but no low surrogate");
// output nothing.
}
}
else // U+DC00 - U+DFFF
{
// DC00- DFFF - Low Surrogate
NS_ERROR("got a low Surrogate but no high surrogate");
// output nothing.
}
}
mBuffer = out;
return N;
}
void write_terminator()
{
*mBuffer = buffer_type(0);
}
private:
buffer_type* const mStart;
buffer_type* mBuffer;
};
/**
* A character sink (see |copy_string| in nsAlgorithm.h) for computing
* the number of bytes a UTF-16 would occupy in UTF-8.
*/
class CalculateUTF8Size
{
public:
typedef nsAString::char_type value_type;
CalculateUTF8Size()
: mSize(0) { }
size_t Size() const { return mSize; }
PRUint32 NS_ALWAYS_INLINE write( const value_type* start, PRUint32 N )
{
// Assume UCS2 surrogate pairs won't be spread across fragments.
for (const value_type *p = start, *end = start + N; p < end; ++p )
{
value_type c = *p;
if (! (c & 0xFF80)) // U+0000 - U+007F
mSize += 1;
else if (! (c & 0xF800)) // U+0100 - U+07FF
mSize += 2;
else if (0xD800 != (0xF800 & c)) // U+0800 - U+D7FF,U+E000 - U+FFFF
mSize += 3;
else if (0xD800 == (0xFC00 & c)) // U+D800 - U+DBFF
{
++p;
if (p == end)
{
NS_ERROR("Surrogate pair split between fragments");
return N;
}
c = *p;
if (0xDC00 == (0xFC00 & c))
mSize += 4;
else
NS_ERROR("got a high Surrogate but no low surrogate");
}
else // U+DC00 - U+DFFF
NS_ERROR("got a low Surrogate but no high surrogate");
}
return N;
}
private:
size_t mSize;
};
/**
* A character sink that performs a |reinterpret_cast| style conversion
* between character types.
*/
template <class FromCharT, class ToCharT>
class LossyConvertEncoding
{
public:
typedef FromCharT value_type;
typedef FromCharT input_type;
typedef ToCharT output_type;
typedef typename nsCharTraits<FromCharT>::unsigned_char_type unsigned_input_type;
public:
LossyConvertEncoding( output_type* aDestination ) : mDestination(aDestination) { }
PRUint32
write( const input_type* aSource, PRUint32 aSourceLength )
{
const input_type* done_writing = aSource + aSourceLength;
while ( aSource < done_writing )
*mDestination++ = (output_type)(unsigned_input_type)(*aSource++); // use old-style cast to mimic old |ns[C]String| behavior
return aSourceLength;
}
void
write_terminator()
{
*mDestination = output_type(0);
}
private:
output_type* mDestination;
};
#endif /* !defined(nsUTF8Utils_h_) */
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