private static int ParseHexEscapeSequence(string s, int startIndex, int limit, StringBuilder sb)
{
if (startIndex == limit)
{
throw new ParseException("hex escape sequence missing.", startIndex, 0);
}
var hexResult = CharUtils.CharToHexValue(s[startIndex++]);
if (hexResult == -1)
{
throw new ParseException("Invalid hex escape sequence.", startIndex - 1, 1);
}
for (; startIndex < limit; startIndex++)
{
var hexDigit = CharUtils.CharToHexValue(s[startIndex]);
if (hexDigit == -1)
{
break;
}
hexResult = (hexResult << 4) | hexDigit;
}
sb.Append((char)hexResult);
return(startIndex);
}
private static int ParseUtf32EscapeSequence(string s, int startIndex, int limit, StringBuilder sb)
{
if (limit - startIndex < 8)
{
throw new ParseException("UTF-32 escape sequence missing.", startIndex, 0);
}
var utf32 = CharUtils.CharToHexValue(s[startIndex++]) << 28 |
CharUtils.CharToHexValue(s[startIndex++]) << 24 |
CharUtils.CharToHexValue(s[startIndex++]) << 20 |
CharUtils.CharToHexValue(s[startIndex++]) << 16 |
CharUtils.CharToHexValue(s[startIndex++]) << 12 |
CharUtils.CharToHexValue(s[startIndex++]) << 8 |
CharUtils.CharToHexValue(s[startIndex++]) << 4 |
CharUtils.CharToHexValue(s[startIndex++]) << 0;
const int highSurrogateStart = 0xd800;
const int highSurrogateEnd = 0xdbff;
const int lowSurrogateStart = 0xdc00;
const int lowSurrogateEnd = 0xdfff;
if (utf32 < 0 || utf32 > 0x10ffff || (utf32 >= highSurrogateStart && utf32 <= lowSurrogateEnd))
{
throw new ParseException("Invalid UTF-32 escape sequence.", startIndex - 8, 8);
}
if (utf32 < 0x10000)
{
sb.Append((char)utf32);
}
else
{
var highSurrogate = (char)(((utf32 >> 10) - 0x40) + highSurrogateStart);
var lowSurrogate = (char)((utf32 & 0x3FF) + lowSurrogateStart);
Debug.Assert(highSurrogate >= highSurrogateStart && highSurrogate <= highSurrogateEnd);
Debug.Assert(lowSurrogate >= lowSurrogateStart && lowSurrogate <= lowSurrogateEnd);
sb.Append(highSurrogate);
sb.Append(lowSurrogate);
}
return(startIndex);
}
private static int ParseUtf16EscapeSequence(string s, int startIndex, int limit, StringBuilder sb)
{
if (limit - startIndex < 4)
{
throw new ParseException("UTF-16 escape sequence missing.", startIndex, 0);
}
var utf16 = CharUtils.CharToHexValue(s[startIndex++]) << 12 |
CharUtils.CharToHexValue(s[startIndex++]) << 8 |
CharUtils.CharToHexValue(s[startIndex++]) << 4 |
CharUtils.CharToHexValue(s[startIndex++]) << 0;
if (utf16 < 0)
{
throw new ParseException("Invalid UTF-16 escape sequence.", startIndex - 4, 4);
}
sb.Append((char)utf16);
return(startIndex);
}
private static int InternalTryParseHexStringToByteArray(string s, int startIndex, int length, byte[] buffer, int offset, int count)
{
var lastChar = startIndex + length;
var lastByte = offset + count;
while (lastByte > offset)
{
if (lastChar <= startIndex)
{
break;
}
var lo = CharUtils.CharToHexValue(s[--lastChar]);
if (lo < 0)
{
return(~lastChar);
}
if (lastChar <= startIndex)
{
buffer[--lastByte] = (byte)lo;
break;
}
var hi = CharUtils.CharToHexValue(s[--lastChar]);
if (hi < 0)
{
return(~lastChar);
}
buffer[--lastByte] = (byte)((hi << 4) | (lo << 0));
}
return(offset + count - lastByte);
}
