private string ParseString(string s)
{
int readPos = 0;
int len = s.Length;
int writePos = 0;
while (readPos < len)
{
char c = s[readPos++];
if (c == '\\')
{
if (readPos >= len)
{
throw new ArgumentException("Invalid escaped char in [" + s + "]");
}
c = s[readPos++];
switch (c)
{
case '\\':
c = '\\';
break;
case 'n':
c = '\n';
break;
case 't':
c = '\t';
break;
case 'r':
c = '\r';
break;
case 'b':
c = '\b';
break;
case 'f':
c = '\f';
break;
case 'u':
if (readPos + 3 >= len)
{
throw new ArgumentException("Invalid escaped char in [" + s + "]");
}
// LUCENENET: Optimized parse so we don't allocate a substring
c = (char)Integer.Parse(s, readPos, 4, radix: 16);
readPos += 4;
break;
}
}
@out[writePos++] = c;
}
return(new string(@out, 0, writePos));
}
internal RegExp ParseRepeatExp()
{
RegExp e = ParseComplExp();
while (Peek("?*+{"))
{
if (Match('?'))
{
e = MakeOptional(e);
}
else if (Match('*'))
{
e = MakeRepeat(e);
}
else if (Match('+'))
{
e = MakeRepeat(e, 1);
}
else if (Match('{'))
{
int start = pos;
while (Peek("0123456789"))
{
Next();
}
if (start == pos)
{
throw new ArgumentException("integer expected at position " + pos);
}
// LUCENENET: Optimized so we don't allocate a substring during the parse
int n = Integer.Parse(b, start, pos - start, radix: 10);
int m = -1;
if (Match(','))
{
start = pos;
while (Peek("0123456789"))
{
Next();
}
if (start != pos)
{
// LUCENENET: Optimized so we don't allocate a substring during the parse
m = Integer.Parse(b, start, pos - start, radix: 10);
}
}
else
{
m = n;
}
if (!Match('}'))
{
throw new ArgumentException("expected '}' at position " + pos);
}
if (m == -1)
{
e = MakeRepeat(e, n);
}
else
{
e = MakeRepeat(e, n, m);
}
}
}
return(e);
}