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/* Compiler implementation of the D programming language
* Copyright (C) 2003-2020 by The D Language Foundation, All Rights Reserved
* written by Walter Bright
* http://www.digitalmars.com
* Distributed under the Boost Software License, Version 1.0.
* http://www.boost.org/LICENSE_1_0.txt
* https://github.com/D-Programming-Language/dmd/blob/master/src/utf.c
*/
/// Description of UTF-8 in [1]. Unicode non-characters and private-use
/// code points described in [2],[4].
///
/// References:
/// [1] http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8
/// [2] http://en.wikipedia.org/wiki/Unicode
/// [3] http://unicode.org/faq/utf_bom.html
/// [4] http://www.unicode.org/versions/Unicode6.1.0/ch03.pdf
#include "utf.h"
/* The following encodings are valid, except for the 5 and 6 byte
* combinations:
* 0xxxxxxx
* 110xxxxx 10xxxxxx
* 1110xxxx 10xxxxxx 10xxxxxx
* 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
* 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
* 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
*/
const unsigned UTF8_STRIDE[256] =
{
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,
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,
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,
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,
0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
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,
3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,
4,4,4,4,4,4,4,4,5,5,5,5,6,6,0xFF,0xFF,
};
// UTF-8 decoding errors
char const UTF8_DECODE_OUTSIDE_CODE_SPACE[] = "Outside Unicode code space";
char const UTF8_DECODE_TRUNCATED_SEQUENCE[] = "Truncated UTF-8 sequence";
char const UTF8_DECODE_OVERLONG[] = "Overlong UTF-8 sequence";
char const UTF8_DECODE_INVALID_TRAILER[] = "Invalid trailing code unit";
char const UTF8_DECODE_INVALID_CODE_POINT[] = "Invalid code point decoded";
// UTF-16 decoding errors
char const UTF16_DECODE_TRUNCATED_SEQUENCE[]= "Truncated UTF-16 sequence";
char const UTF16_DECODE_INVALID_SURROGATE[] = "Invalid low surrogate";
char const UTF16_DECODE_UNPAIRED_SURROGATE[]= "Unpaired surrogate";
char const UTF16_DECODE_INVALID_CODE_POINT[]= "Invalid code point decoded";
/// The Unicode code space is the range of code points [0x000000,0x10FFFF]
/// except the UTF-16 surrogate pairs in the range [0xD800,0xDFFF]
/// and non-characters (which end in 0xFFFE or 0xFFFF).
bool utf_isValidDchar(dchar_t c)
{
// TODO: Whether non-char code points should be rejected is pending review
// largest character code point
if (c > 0x10FFFF)
return false;
// surrogate pairs
if (0xD800 <= c && c <= 0xDFFF)
return false;
// non-characters
if ((c & 0xFFFFFE) == 0x00FFFE)
return false;
return true;
}
/*******************************
* Return !=0 if unicode alpha.
* Use table from C99 Appendix D.
*/
bool isUniAlpha(dchar_t c)
{
size_t high = ALPHA_TABLE_LENGTH - 1;
// Shortcut search if c is out of range
size_t low
= (c < ALPHA_TABLE[0][0] || ALPHA_TABLE[high][1] < c) ? high + 1 : 0;
// Binary search
while (low <= high)
{
size_t mid = (low + high) >> 1;
if (c < ALPHA_TABLE[mid][0])
high = mid - 1;
else if (ALPHA_TABLE[mid][1] < c)
low = mid + 1;
else
{
assert(ALPHA_TABLE[mid][0] <= c && c <= ALPHA_TABLE[mid][1]);
return true;
}
}
return false;
}
/**
* Returns the code length of c in code units.
*/
int utf_codeLengthChar(dchar_t c)
{
if (c <= 0x7F)
return 1;
if (c <= 0x7FF)
return 2;
if (c <= 0xFFFF)
return 3;
if (c <= 0x10FFFF)
return 4;
assert(false);
return 6;
}
int utf_codeLengthWchar(dchar_t c)
{
return c <= 0xFFFF ? 1 : 2;
}
/**
* Returns the code length of c in code units for the encoding.
* sz is the encoding: 1 = utf8, 2 = utf16, 4 = utf32.
*/
int utf_codeLength(int sz, dchar_t c)
{
if (sz == 1)
return utf_codeLengthChar(c);
if (sz == 2)
return utf_codeLengthWchar(c);
assert(sz == 4);
return 1;
}
void utf_encodeChar(utf8_t *s, dchar_t c)
{
assert(s != NULL);
assert(utf_isValidDchar(c));
if (c <= 0x7F)
{
s[0] = static_cast<utf8_t>(c);
}
else if (c <= 0x07FF)
{
s[0] = static_cast<utf8_t>(0xC0 | (c >> 6));
s[1] = static_cast<utf8_t>(0x80 | (c & 0x3F));
}
else if (c <= 0xFFFF)
{
s[0] = static_cast<utf8_t>(0xE0 | (c >> 12));
s[1] = static_cast<utf8_t>(0x80 | ((c >> 6) & 0x3F));
s[2] = static_cast<utf8_t>(0x80 | (c & 0x3F));
}
else if (c <= 0x10FFFF)
{
s[0] = static_cast<utf8_t>(0xF0 | (c >> 18));
s[1] = static_cast<utf8_t>(0x80 | ((c >> 12) & 0x3F));
s[2] = static_cast<utf8_t>(0x80 | ((c >> 6) & 0x3F));
s[3] = static_cast<utf8_t>(0x80 | (c & 0x3F));
}
else
assert(0);
}
void utf_encodeWchar(utf16_t *s, dchar_t c)
{
assert(s != NULL);
assert(utf_isValidDchar(c));
if (c <= 0xFFFF)
{
s[0] = static_cast<utf16_t>(c);
}
else
{
s[0] = static_cast<utf16_t>((((c - 0x010000) >> 10) & 0x03FF) + 0xD800);
s[1] = static_cast<utf16_t>(((c - 0x010000) & 0x03FF) + 0xDC00);
}
}
void utf_encode(int sz, void *s, dchar_t c)
{
if (sz == 1)
utf_encodeChar((utf8_t *)s, c);
else if (sz == 2)
utf_encodeWchar((utf16_t *)s, c);
else
{
assert(sz == 4);
*((utf32_t *)s) = c;
}
}
/********************************************
* Decode a UTF-8 sequence as a single UTF-32 code point.
* Returns:
* NULL success
* !=NULL error message string
*/
const char *utf_decodeChar(utf8_t const *s, size_t len, size_t *pidx, dchar_t *presult)
{
assert(s != NULL);
assert(pidx != NULL);
assert(presult != NULL);
size_t i = (*pidx)++;
assert(i < len);
utf8_t u = s[i];
// Pre-stage results for ASCII and error cases
*presult = u;
//printf("utf_decodeChar(s = %02x, %02x, %02x len = %d)\n", u, s[1], s[2], len);
// Get expected sequence length
size_t n = UTF8_STRIDE[u];
switch (n)
{
case 1: // ASCII
return UTF8_DECODE_OK;
case 2: case 3: case 4: // multi-byte UTF-8
break;
default: // 5- or 6-byte sequence
return UTF8_DECODE_OUTSIDE_CODE_SPACE;
}
if (len < i + n) // source too short
return UTF8_DECODE_TRUNCATED_SEQUENCE;
// Pick off 7 - n low bits from first code unit
utf32_t c = u & ((1 << (7 - n)) - 1);
/* The following combinations are overlong, and illegal:
* 1100000x (10xxxxxx)
* 11100000 100xxxxx (10xxxxxx)
* 11110000 1000xxxx (10xxxxxx 10xxxxxx)
* 11111000 10000xxx (10xxxxxx 10xxxxxx 10xxxxxx)
* 11111100 100000xx (10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx)
*/
utf8_t u2 = s[++i];
// overlong combination
if ((u & 0xFE) == 0xC0 ||
(u == 0xE0 && (u2 & 0xE0) == 0x80) ||
(u == 0xF0 && (u2 & 0xF0) == 0x80) ||
(u == 0xF8 && (u2 & 0xF8) == 0x80) ||
(u == 0xFC && (u2 & 0xFC) == 0x80))
return UTF8_DECODE_OVERLONG;
// Decode remaining bits
for (n += i - 1; i != n; ++i)
{
u = s[i];
if ((u & 0xC0) != 0x80) // trailing bytes are 10xxxxxx
return UTF8_DECODE_INVALID_TRAILER;
c = (c << 6) | (u & 0x3F);
}
if (!utf_isValidDchar(c))
return UTF8_DECODE_INVALID_CODE_POINT;
*pidx = i;
*presult = c;
return UTF8_DECODE_OK;
}
/********************************************
* Decode a UTF-16 sequence as a single UTF-32 code point.
* Returns:
* NULL success
* !=NULL error message string
*/
const char *utf_decodeWchar(utf16_t const *s, size_t len, size_t *pidx, dchar_t *presult)
{
assert(s != NULL);
assert(pidx != NULL);
assert(presult != NULL);
size_t i = (*pidx)++;
assert(i < len);
// Pre-stage results for ASCII and error cases
utf32_t u = *presult = s[i];
if (u < 0x80) // ASCII
return UTF16_DECODE_OK;
if (0xD800 <= u && u <= 0xDBFF) // Surrogate pair
{ if (len <= i + 1)
return UTF16_DECODE_TRUNCATED_SEQUENCE;
utf16_t u2 = s[i + 1];
if (u2 < 0xDC00 || 0xDFFF < u)
return UTF16_DECODE_INVALID_SURROGATE;
u = ((u - 0xD7C0) << 10) + (u2 - 0xDC00);
++*pidx;
}
else if (0xDC00 <= u && u <= 0xDFFF)
return UTF16_DECODE_UNPAIRED_SURROGATE;
if (!utf_isValidDchar(u))
return UTF16_DECODE_INVALID_CODE_POINT;
*presult = u;
return UTF16_DECODE_OK;
}
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