public static string ParseString(this TextReader reader, ref int c)
{
if (!c.IsQuoteChar())
{
return(null);
}
int q = c;
var sb = new StringBuilder();
while (true)
{
c = reader.Read();
if (c < 0)
{
return(null);
}
if (c == q)
{
c = reader.Read();
break;
}
if (c == '\\')
{
c = reader.Read();
if (c == 'u')
{
int h = 0;
for (int i = 0; i < 4; ++i)
{
c = reader.Read();
if (c < 0)
{
throw new FormatException("Unexpected end of stream");
}
if (!c.IsHexDigit())
{
throw new FormatException(
string.Format("Bad unicode symbol. '{0}' is not hex digit.", (char)c));
}
h += Hex.ToDecimal(c);
}
sb.Append((char)h);
}
else if (c == 'x')
{
int h = 0;
int n = 0;
while (true)
{
c = reader.Read();
if (c < 0)
{
throw new FormatException("Unexpected end of stream");
}
if (!c.IsHexDigit())
{
break;
}
++n;
h += Hex.ToDecimal(c);
}
if (n == 0)
{
sb.Append("\\x");
}
else
{
sb.Append((char)h);
}
}
else if (Escaper.UnescapeChar(ref c))
{
sb.Append((char)c);
}
else
{
sb.Append('\\');
sb.Append((char)c);
}
}
else
{
sb.Append((char)c);
}
}
return(sb.ToString());
}
