private bool TryReadEscapeChar(ref TextPosition end)
{
if (_c == '\\')
{
end = _position;
NextChar();
// 0 \ ' " a b f n r t v u0000-uFFFF x00-xFF
switch (_c)
{
case 'b':
_textBuilder.Append('\b');
end = _position;
NextChar();
return(true);
case 't':
_textBuilder.Append('\t');
end = _position;
NextChar();
return(true);
case 'n':
_textBuilder.Append('\n');
end = _position;
NextChar();
return(true);
case 'f':
_textBuilder.Append('\f');
end = _position;
NextChar();
return(true);
case 'r':
_textBuilder.Append('\r');
end = _position;
NextChar();
return(true);
case '"':
_textBuilder.Append('"');
end = _position;
NextChar();
return(true);
case '\\':
_textBuilder.Append('\\');
end = _position;
NextChar();
return(true);
// toml-specs: When the last non-whitespace character on a line is a \,
// it will be trimmed along with all whitespace (including newlines)
// up to the next non-whitespace character or closing delimiter.
case '\r':
case '\n':
while (CharHelper.IsWhiteSpaceOrNewLine(_c))
{
end = _position;
NextChar();
}
return(true);
case 'u':
case 'U':
{
var start = _position;
end = _position;
var maxCount = _c == 'u' ? 4 : 8;
NextChar();
// Must be followed 0 to 8 hex numbers (0-FFFFFFFF)
int i = 0;
int value = 0;
for (; CharHelper.IsHexFunc(_c) && i < maxCount; i++)
{
value = (value << 4) + CharHelper.HexToDecimal(_c);
end = _position;
NextChar();
}
if (i == maxCount)
{
if (!CharHelper.IsValidUnicodeScalarValue(value))
{
AddError($"Invalid Unicode scalar value [{value:X}]", start, start);
}
_textBuilder.AppendUtf32((char32)value);
return(true);
}
}
break;
}
AddError($"Unexpected escape character [{_c}] in string. Only b t n f r \\ \" u0000-uFFFF U00000000-UFFFFFFFF are allowed", _position, _position);
return(false);
}
return(false);
}